Determinants of failure in superficial femoral artery angioplasty.

Although results of iliac artery balloon angioplasty have been shown to be good, there are much less data regarding initial success and durability of superficial femoral artery (SFA) dilation. The authors retrospectively reviewed the results of 22 patients treated for 27 SFA lesions between 1981 and 1986. Mean age was 64.5 years (fifty-five to seventy-six). Results were analyzed with respect to initial, early (< twelve months), and late (> twelve months) angiographic and clinical success. Indications were claudication (22), nonhealing ulcer (3), and rest pain (2). Mean follow-up was 30.9 months; 100% at one year and 92% at two years. Initial failure occurred in 9 (33%) lesions. There were 2 early and 2 late failures for a cumulative patency rate of 90.3% and 78% at one and two years, respectively. Predictors of clinical failure were: (1) initial--age, SFA occlusion, and angioplasty rating; (2) early--age, SFA occlusion, degree of atherosclerosis, and angioplasty rating; (3) late--angioplasty rating. There were 3 complications (11%). The authors conclude that: (1) 33% of attempted SFA angioplasties were initially unsuccessful and that the cumulative patency rate was 78% at two years. (2) Age is predictive of initial and early failure; SFA occlusion, of initial and early failure; degree of atherosclerosis, of early failure; and angioplasty appearance, of initial, early, and late failures. (3) Complications did not result in limb loss or require surgery.


Immediate anticoagulation for intracardiac thrombus in acute cardioembolic stroke.

To assess the efficacy of immediate anticoagulation therapy on intracardiac thrombus formation in acute cardioembolic stroke, serial two-dimensional echocardiographic examinations were performed in 25 patients with acute cardioembolic stroke. Anticoagulation therapy was commenced within two days of onset in 7 patients (group A) but not in 18 patients (group B). Appearance or enlargement of intracardiac thrombi were not detected in group A but were noted in 7 patients (39%) of group B. Recurrence of systemic embolism was demonstrated in 3 patients (17%) of group B. There were no serious hemorrhagic complications in either group. Immediate anticoagulation could, therefore, be effective in preventing intracardiac thrombus formation and the consequent recurrence of systemic embolization in acute cardioembolic stroke. Because the study was preliminary and not randomized, further randomized study is desirable to establish the efficacy of immediate anticoagulation therapy.


Procion yellow fluorescent microscopy: a new method of studying arterial and venous pathology.

A new means of studying vessel wall pathology is presented. This technique utilizes Procion yellow, a vital fluorescent dye, to stain and delineate the connective elements, matrix, and elastic tissue within the arterial wall. In addition, penetration of the dye into cells provides evidence of membrane pathology. A canine model was used, and clamped segments of femoral artery were stained and examined. The appreciation of this approach for the examination of the vessel wall shows alterations in tissue elements that have not been reported previously. This technique makes possible a unique means of studying connective tissue elements as well as membrane integrity.


Microcirculation in systemic hypertension.

In 40 patients with idiopathic systemic hypertension, skin blood flow was evaluated with laser-Doppler flowmetry, transcutaneous measurements of partial pressure of oxygen (PO2) and partial pressure of carbon dioxide (PCO2), and determination of capillary permeability before and after treatment with nifedipine (10 mg tid for four weeks). Also 35 normal subjects matched for age and sex distribution were studied. Before treatment, microcirculatory studies showed a significant decrease in skin flow and venoarteriolar response in hypertensive patients in comparison with normal subjects. Moreover, PO2, PCO2, and capillary permeability were significantly lower in hypertensives. All these microcirculatory parameters significantly increased after nifedipine treatment while both systolic and diastolic pressures decreased. In conclusion, laser-Doppler flowmetry used with other microcirculatory techniques was able to discriminate between normal subjects and hypertensive patients, and it was able to show the improvement in the microcirculation after nifedipine treatment.


Vascular effects of noise.

The possible vascular effects of noise were studied. A study of the carotid vessels was made with Doppler ultrasonography in two groups of subjects exposed to various intensity of noise. The following data were studied: age, blood pressure, serum cholesterol, blood glucose, smoking habits, excess weight, electrocardiographic anomalies, family history of vascular disease, connection with duration of exposure and the type of noise and with audiometric deficits, and cerebrovascular modifications after postural changes and after a stress test. The control group comprised subjects not exposed to noise. The findings confirm that noise does play a role in causing vascular modifications that can be detected early by use of Doppler ultrasonography. This technique is predictive and could be useful in screening campaigns, following the method suggested here.


Assessment of valvular regurgitation using cine magnetic resonance imaging coupled with phase compensation technique: comparison with Doppler color flow mapping.

To elucidate whether or not a newly developed technique in cinematic-displayed (cine) magnetic resonance imaging (MRI) can improve the semiquantitative evaluation of valvular regurgitant flow, 20 patients with valvular lesions were studied. Three pulse sequences of cine MRI, ie, standard, short echo time (TE), and rephasing scans, were compared with reference obtained by Doppler color flow mapping. Short TE technique and rephasing scan technique improved image quality remarkably as compared with standard technique. Each of the three cine MRI techniques showed good correlation with the Doppler method (p < 0.001). However, short TE and rephasing scan techniques gave a faithful estimation of the extent as compared with the Doppler method, whereas standard technique overestimated the regurgitation. Thus, cine magnetic resonance imaging with phase compensation technique can be utilized for the semiquantitative assessment of valvular regurgitation in a manner similar to that of Doppler color flow mapping.


Lymphoscintigraphy of head-and-neck cancer.

To achieve the visualization of regional lymph nodes by lymphoscintigraphy, 21 patients with head-and-neck cancer were studied with the aid of 99mTc-labeled rhenium sulfur colloid (99mTc Re). Four injection sites were selected; the injections were given into the subcutaneous tissue of the parietal area of 11 patients, into the submucosa of the retromolar area of 6 patients, into the subcutaneous tissue of the postauricular area of 2 patients, and into the thyroid glands of 2 patients. Lymphoscintigraphy was done three hours after the injection. The cervical regions were visible in 85.7% of the patients on the affected side and in 90.5% on the healthy side. The visualization comprised the following regions: submental, submandibular, deep cervical, accessory, and supraclavicular regions. In total, 102 nodes were visualized on the affected side (average 4.8 per patient) and 110 nodes in the healthy side (average 5.5). Histologically, 15 of 21 patients had lymph nodes metastases and 6 did not. Of these 21 patients, 66.7% (14/21) had confirmed lymph node metastases in the visualized regions. This technique appears to be a relatively easy and efficient method of imaging the regional lymph nodes in head-and-neck cancer both before treatment and after neck surgery.


Role of the captopril test in renovascular hypertension: a case report.

This article reports the case of a rapidly severe stenosis of the right renal artery, causing uncontrolled hypertension. After failure of a percutaneous transluminal renal angioplasty, which provoked the thrombosis of the vessel, a surgical revascularization was performed after +/- eighteen hours of renal ischemia. Blood pressure, blood urea nitrogen and serum creatinine returned to normal values. A dramatic improvement of the right renal function was attested at the hippuran scintigraphy after a dose test of captopril. The results of renographic studies obtained in this clinical case underline the role of the captopril radionuclide test in detection and follow-up after treatment of renovascular hypertension.


A case of ventricular tachycardia refractory to medical treatment related to a cystic mass in left ventricle--a case report.

This is a case report of a twenty-two-year-old woman who had attacks of ventricular tachycardia that could be prevented by the use of various antiarrhythmic drugs for three months. Electrophysiologic study showed that the mechanism of the tachycardia was "reentry." In cardiac catheterization a non-contractile mass having calcification was seen on the apical portion of the left ventricle. Angiographically, the mass resembled a diverticulum. Recurrence of attacks was terminated by resection of this mass, which had a cystic appearance.


Pulmonary artery catheterization: the right heart should not be left out--a case report.

Tricuspid valve stenosis in the setting of endocarditis is associated with a high morbidity. Diagnostic approaches incorporate a high clinical index of suspicion, echocardiographic evidence, and inferences about hemodynamic data derived from pulmonary artery catheterization. As demonstrated by the case presented herein, inadequate initial evaluation of right-sided pressures delayed the diagnosis and treatment of prosthetic tricuspid valve stenosis.


Biochemical evidence of the expression of two major histocompatibility complex class I genes on bovine peripheral blood mononuclear cells.

For a long time, the bovine major histocompatibility complex (MHC) (BoLA) class I region was characterized, rather uniquely among mammalian species, as having one expressed locus. Recent reports have suggested otherwise. Selective immunoprecipitation and molecular characterization of products enable a decisive answer to the question of whether there is indeed more than one locus expressed. Therefore, we characterized serologically defined w10 encoding haplotypes in European and African cattle by immunoprecipitation of [35S]-methionine-labelled peripheral blood mononuclear cells (PBMC), followed by one- and two-dimensional isoelectric focusing (1D/2D-IEF) of cell lysates. Monoclonal antibodies (mAb) used were directed against either human class I monomorphic determinants (W6/32 and B1.1G6) or bovine polymorphic determinants expressed on products encoded by serologically defined w10 encoding haplotypes of Boran and Friesian cattle. Sequential immunoprecipitations with W6/32 and B1.1G6 using lysates of PBMC of British Friesian cattle, revealed that from this haplotype W6/32 precipitated one product, whereas B1.1G6 precipitated two products. The product precipitated in addition appeared to be the one that was selectively precipitated by the mAb directed against polymorphic determinants on a product of w10 encoding haplotypes. Additionally, peptide maps of protease V8-digested precipitates showed that this particular 'w10' associated product was distinctly different from the product recognized by W6/32. Thus, we suggest that the two products are distinct gene products and that the product with higher pI is associated with the serologically defined A-locus product, whereas the product with lower pI is the putative second locus product. In the African Boran breed, variants of the serologically defined w10 specificity were found on the basis of IEF typing. These variants appeared to be associated with different second locus products. Therefore, we conclude that serologically defined w10 encoding haplotypes encode at least two independent class I locus products, expressed on normal bovine PBMC. In IEF analysis the additional use of mAb recognizing polymorphic determinants on serologically defined A-locus products highly facilitated the detection and typing of second locus products.


Cloning of highly polymorphic microsatellites in the horse.

We have isolated equine microsatellites by screening a genomic library with (TG)n and (TC)n probes. TG microsatellites were found to be more abundant than TC repeats, with an estimated frequency of one per 100,000bp. Sequence analysis of eight TG-positive clones revealed varying structures of the repeat regions; perfect stretches of TG repeats, imperfect stretches of TG repeats and compound regions of TG and TC repeats. Five loci were analysed by PCR and showed extensive polymorphism; three to seven alleles and heterozygosities of 0.40-0.76 were observed when screening 20-30 unrelated individuals. The high degree of polymorphism, their abundance and the possibility of automating the typing procedure make these loci ideal for standardized paternity testing in the horse. Furthermore, we demonstrate that single hairs can be used as starting material for the PCR analysis.


Genetic polymorphism and close linkage of two plasma protein loci in dogs.

By using a simple method of two-dimensional horizontal electrophoresis, phenotypes of an unidentified plasma protein (PA4) were determined in 967 dogs belonging to 43 different breeds. Two codominant, autosomal alleles (F and S) of PA4 were reported. While many of the breeds of middle and north-eastern Asia (akita inu, Alaskan malamute, chow chow, samoyed, Siberian husky and Tibetan terrier) showed a substantial frequency (0.1 to 0.6) of the S allele, a majority of the European breeds had only the F allele. Evidence was provided that the PA4 locus is closely linked to the plasma pretransferrin 1 locus (PRT1). No recombinant was observed in 45 informative offspring studied. In nearly all breeds, the PA4 S allele was almost always in coupling phase with the PRT1 F allele.


Genetic distances estimated from DNA fingerprints in crosses of white Plymouth Rock chickens.

Crosses were produced between two lines of White Plymouth Rock chickens, one of which had been selected for low 8-week body weight for 31 generations (L) and the other of which was a bantam population (B). The parental lines, reciprocal F1s, reciprocal F2s and all possible back-crosses to each parental line (total of 16 populations) were available for study. Blood was obtained from 10 females within each population. DNA was extracted from blood mixes (equal amounts of blood from each individual) for each population, and from blood samples of each individual in the two parental lines. Fourteen line-specific DNA fingerprint (DFP) bands (those bands present in one parental population, but not in the other parental population) were analysed (eight from line L and six from line B). Regression analyses were conducted to compare the known proportion of genomic contribution from each parental population with values based on relative band intensity obtained with a scanning densitometer. The resulting regression coefficient of 1.004 demonstrated that DFP analysis of relative band intensity is an effective method of estimating the relative proportion of genome contributed by parental populations.


Rapid beta-lactoglobulin genotyping of cattle using the polymerase chain reaction.

A polymerase chain reaction (PCR) assay has been developed for genotyping beta-lactoglobulin A and B variants in dairy cattle. Either blood or semen samples can be used as a source of DNA. The method is accurate, faster than Southern blot analyses and should prove a useful tool in breeding programmes.


Alloreactive T-cell recognition of bovine major histocompatibility complex class II products defined by one-dimensional isoelectric focusing.

T-cell recognition of bovine MHC (BoLA) class II antigens was investigated in relation to BoLA class II polymorphisms defined by one-dimensional isoelectric focusing (1D-IEF). One-way mixed lymphocyte reactions (MLRs), and allospecific cell lines and clones were used. In general, T-cell responses correlated with the 1D-IEF defined haplotypes (EDF types). However, with MLRs some responses appeared to be associated with BoLA class I differences. All combinations of responder-stimulator pairs produced alloreactive T-cell responses both in MLR and in generation of allolines/clones. Thus allospecific lines and clones were generated to all EDF types tested. Splits in the IEF typing were observed with EDF6 and EDF3, indicating that distinct BoLA class II haplotypes are not necessarily distinguished by 1D-IEF alone. Furthermore, the patterns of reactivity with EDF3 expressing cells were complex with the T-cell specificities splitting EDF3 into several distinct types. Also, in some cases it was clear that more than one T-cell specificity per EDF type was detectable. Thus, allospecific lines and clones provide complementary and additional information to the 1D-IEF typing for polymorphism of the BoLA class II complex. This extra information is particularly important in terms of the functional significance of the BoLA complex for antigen presentation and immune response gene effects.


[Sialic acid deficiency transferrin: a very promising biological marker, sensitive to chronic alcoholism].

Chronical alcohol ingestion may induce conformational molecular modifications of plasma transferrin: alcohol modifies the content of its carbohydrates. The abnormal transferrin contains reduced amounts of carbohydrates, especially sialic acid, constituting its terminal trisaccharides biantennary chains. Plasma levels of partly deficient or asialotransferrin increase in chronically drinkers. In English speaking countries, it is called carbohydrate deficient transferrin or CDT. A positive correlation is obtained between the plasmatic concentration of CDT and the amount of ingested alcohol. Positivity and sensitivity of CDT are superior to those other usual biological parameters. The CDT quantitation may be proposed for the detection and the follow-up of alcohol drinkers, in order to evaluate the degree of intoxication, and during the period of withdrawal.


[Variations of plasma Willebrand factor and fibrinogen in coronary pathology].

In order to determine a marker of prethrombotic states, reliable and easy to measure, we studied 200 patients under 60 years of age admitted to hospital for a precordial chest pain. Four groups were established: transmural myocardial infarction, acute infarction without Q wave, unstable angina and atypical chest pain. Fibrinogen, von Willebrand factor, cholesterol, and triglyceride levels were measured as well as the white cell and platelet counts. There was a statistically significant correlation between transmural myocardial infarction and increased levels of fibrinogen, von Willebrand factor and white blood cells. Von Willebrand factor was already increased in the acute phase of transmural infarction, reached a maximum on the fifth day and then decreased slowly during the following ten days. This study suggests that plasma von Willebrand factor could be a reliable marker of transmural myocardial infarction in the acute phase or during the two weeks following the thrombotic event.


[Assay of micronuclei in binucleated T-lymphocytes. Analysis of the distribution and variation factors in a population of 100 subjects].

The authors analysed micronuclei levels distribution in lymphocytes of 100 non occupationally exposed subjects and studied the effect of age, sex and smoking of donors on the distribution. Results showed that micronucleated cells were distributed according to a normal distribution (average = 9.5 +/- 4 micronucleated cells in 1,000 binucleated lymphocytes). Age and sex of donors had no effect on the distribution but, concerning smoking, the results showed that micronuclei levels were correlated to the number of cigarettes daily smoked.


[Comparison of different methods for serum folate assay].

Folates were determined in 148 patient sera, using four different methods: a microbiological assay (Reference Method), two radioassays (Magic B12 FOL [NB] and SimulTRAC SNB no boil kits) and a non isotopic competition method (Magic Lite kit). Folate mean varied according to the methods 10.0 nmol.l-1 (reference method), 12.2 nmol.l-1 (Magic Lite), 8.7 nmol.l-1 (Magic B12 FOL [NB]) and 10.8 nmol.l-1 (SimulTRAC SNB NO boil). Poor correlations were also noted (0.83 < r < 0.95, figures 1 and 2). Differences between methods were explained according to the literature.


[Evaluation of the immunoenzyme test (Elisa) in detecting Clostiridium difficile toxin A in fecal samples].

Currently, the method of choice in diagnosis of Clostridium difficile-associated intestinal diseases is the detection of toxin B in fecal specimens. This method is long (72 h) and can be realized in laboratories which have tissue culture facilities. Commercial agglutination test have been evaluated but they lack in specificity. An immunoenzymatic test has been recently commercialized for detection of toxin A. We have compared the results of this assay on 275 fecal specimens from patients suspected of having Clostridium difficile-associated intestinal diseases with the results obtained with the cytotoxicity test and the culture. Of the 275 fecal specimens, 58 were positive in cytotoxicity and 53 in Elisa. The overall sensitivity and specificity of the Elisa compared with cytotoxicity were 89.5% and 99.0% respectively. The immunoenzymatic test detecting Clostridium difficile toxin A is an easy test to perform in 2 h 15; it displays a good correlation with detection of toxin B and can be very useful in daily laboratory diagnosis.


Erythrocyte metabolic alterations in type I diabetes: relationship to metabolic control.

Erythrocytes from young type I diabetic patients (n = 11), incubated in their plasma in anaerobic conditions, exhibited higher glucose consumption than cells from controls (n = 11). This increased metabolic activity is believed to reflect erythrocyte alterations dependent on the degree of metabolic control, as glucose consumption was significantly correlated to glycosylated haemoglobin (HbA1) and to glucose levels (P < 0.05 and P < 0.01 respectively). Red cell hexokinase (HK) and pyruvate kinase (PK) activities were similar in both groups whereas phosphofructokinase (PFK) activity was slightly higher in patients' cells (P < 0.05). No difference was found between patients and controls for red cell ATP and 2.3 diphosphoglycerate (2.3 DPG) levels. However, the concentrations of these glycolytic products seem also closely related to the glucose homeostasis in diabetes. Indeed, within the diabetic group, ATP levels showed a negative relationship with glucose level (P < 0.05) and 2.3 DPG a positive relationship with HbA1 (P < 0.05). In conclusion, higher glycolytic activity is present in young diabetic red cells. This activity as well as ATP and 2.3 DPG levels are related to the degree of short- or long-term diabetic control. These findings stress the importance of a careful metabolic control to avoid haematological disturbances.


[Rapid identification of Candida albicans: evaluation of "Rapidec albicans". Study of 444 yeast strains].

Rapid identification of Candida albicans is of great importance as it is the most frequently isolated yeast pathogen. Rapidec albicans, a new 2-h micromethod, performs two fluorescent enzymatic activities: hexosaminidase and proline arylamidase. A total of 444 yeast strains (334 from type culture collections and 110 from recent clinical isolates) were tested. The sensitivity was 98.5% and the specificity 95.8%. When only considering the clinical strains, 47/47 Candida albicans were identified by Rapidec albicans (sensitivity 100%) but only 43/47 by the germ tube test (sensitivity 91.5%). The specificities of the two tests were respectively 98.2% and 100%. This new system is therefore very efficient for the routine diagnosis of Candida albicans in the clinical field. It is easier and quicker than the germ tube test.


[Metabolism of amino acids and urea cycle: animal models of enzymopathies].

This article is a review of the animal models which have been described until now for the inborn errors of amino acid metabolism and urea cycle. Two approaches have been explored to obtain such animal models: firstly oral or parenteral administration of the amino acid(s) accumulated in some enzymatic defects of the amino acid catabolism or urea cycle--specific enzymatic inhibitors have sometimes been used; secondly, the genetic approach, which is often the best method. Systematic screening of rat or mouse mutants obtained by experimental mutagenesis was performed in some cases. The relationships between the metabolic disturbances observed either in the inborn errors of metabolism or in the experimental models are discussed as well as the origin of the discrepancies often observed between human and animal syndromes.


[Optimization of a spectrophotometry assay of total and oxidized blood glutathione: comparison with a fluorimetric method].

We developed a method for the enzymatic assay of glutathione which is easy to practice, rapid, specific, based on the reaction of the thiol group of glutathione with dithiobis-nitrobenzoic acid after the action of glutathione reductase in the presence of NADPH. This spectrophotometric technique allowed, on the one hand, the determination of total glutathione and on the other hand, that of oxidized glutathione (disulfide), after the blockage of reduced glutathione by 2-vinyl-pyridine. The improvements of the assay of blood glutathione concerned the sample preparation, the reaction sensitivity, thanks to a better definition of the optimal pH and a reduction ot the blockage time by 2-vinyl-pyridine in well defined operating conditions. We compared the performances of our technique with a fluorimetric method. We used our method for the determination of total and oxidized blood glutathione in a control population.


[Determination of mannitol and lactulose in urine by capillary gas chromatography].

Gas capillary chromatography (GCC) determination of mannitol and lactulose in urine after oral intake is a method for assessing the intestinal permeability in various bowel diseases. The method proposed, using gas capillary chromatography with flame ionization detection after silylation of urine residue, gives good results: coefficients of variation varied from 6 to 8.7% for mannitol and 7.5 to 13.7% for lactulose. Detection limit was 5 mg/l for both compounds.


[Serum creatinine assay: results of a multicentric study with 16 analytical systems].

During a multicenter evaluation, 16 methods for creatinine measurement have been tested according to the guidelines of the Société française de biologie clinique (SFBC) protocol. Kinetic Jaffé methods, widely used in France, performed on different analytical systems (Astra Beckman, IL 508, RA 1000 Technicon, Hitachi 704, 705, 717 Boehringer, Fara Roche, Progress Kone, Kem-O-Mat Coulter, Perspective France Monitor) have been compared to a continuous flow method with aqueous standards, to enzymatic methods using creatinine amidohydrolase with a colorimetric measurement (Boehringer and Ektachem Kodak) and to an HPLC method. Reproducibility, estimated with four different control sera, proved to be unsatisfactory in some cases as compared to current criteria for imprecision (less than +/- 10 mumol/l for intralaboratory and less than +/- 20 mumol/l for interlaboratory imprecision). The same selected patients sera covering the whole range of physiopathological concentrations have been analyzed with each method, and compared with the continuous flow results. Differences are more dependent on the sample than on the calibrators. The influences of haemolysis, bilirubin, acetoacetate, albumin, lipids, glucose, and some cephalosporins have been evaluated with spiked human sera. Haemolysed, turbid and jaundiced patient samples have been analyzed as well. The results vary according to the analytical procedure. This study took place in the implementation of a selected method for routine purpose with special regards to interferences and an acceptable imprecision. The method must satisfy the physicians' demands in the renal function exploration, especially in kidney-transplant patients.


[Malaria in the Dunkerque hospital center from December 1979 to December 1990].

Seventy-one cases of malaria were diagnosed in the hospital of Dunkerque from 1979 to 1990. Forty-five patients have been infected in the Comores islands. Among the 24 other imported cases, 17 (71%) have been contaminated in Western or Central Africa. One case of congenital malaria and one of malaria acquired by blood transfusion are also reported. Plasmodium falciparum was detected in 84.5% of the patients. The four human species were found among the Comorians. Two cases with abnormal forms of Plasmodium vivax were observed.


[Perforation of the esophagus during attempted endotracheal intubation].

A case is reported of oesophageal perforation which occurred during an attempt to carry out endotracheal intubation. A 54-year-old female patient was scheduled for mastectomy. She had no clinical features likely to predict a difficult endotracheal intubation. After induction with thiopentone, phenoperidine and suxamethonium, three attempts were made to carry out tracheal intubation with a Mallinckrodt Lo-pro tube, internal diameter 7.5 mm. During the third attempt, the oesophagus was accidentally intubated. The diagnosis was made before any insufflation was carried out. Another anaesthetist took over, and intubated the patient. At that time, there was left-sided cervical emphysema which quickly spread. An oesophageal perforation was suspected, and the patient was given 500 mg of metronidazole and 1 g of cefotetan. Postoperatively, the antibiotics were continued, and the patient had nothing by mouth. Oesophagography showed a posterior fistula in the upper third. Conservative treatment was continued until the seventh day, when another oesophagography was carried out. This showed that the perforation had completely healed. This rather rare complication of endotracheal intubation may have a poor prognosis if it results in mediastinitis. The diagnosis and prognosis of this complication and its treatment, whether conservative or surgical, are discussed.


[Pulmonary pasteurellosis in a young patient with multiple trauma].

A case is reported of an 18-year-old male patient who had a road traffic accident, with head and chest injuries. The patient was admitted to the surgical intensive care unit 24 h later because of an alteration of his level of consciousness. He required artificial ventilation. Five days later, he developed right-sided lower lobe pneumonia, treated with positive end-expiratory pressure. A Gram negative organism was found on bronchial brushing, but not in haemocultures. It was identified as Pasteurella multocida, sensitive to beta-lactamines, but not to amikacin. Cefotaxime, which had been started immediately after the arrival of the Gram stain result, was continued. Artificial ventilation was discontinued on day 12, and the patient left the unit on day 15. The patient was probably a P. multocida carrier, being in close contact with animals before his accident. This bacteria is often found in infected animal bite wounds. Pneumonia due to this bacteria usually occurs in immunodepressed patients, which was not the case here.


[Fatal poisoning caused by African viper's bite (Echis carinatus)].

The case is reported of a 44-year-old European who was bitten on the foot in Djibouti, probably by an African viper. Unusually, there wasn't any pain, nor any cardiovascular collapse nor any local swelling. An oedema of the lower limb started the day afterwards. Two days after the bite, the patient presented a generalized haemorrhagic syndrome, which led to his admission. There was a consumption of fibrinogen and prothrombin, without any decrease in the platelet count. Heparin was started (100 IU.kg-1.day-1), as well as fluid replacement (albumin, fresh frozen plasma, packed red cells). This allowed him to be transferred to France, where he arrived in anuria, with hyperpyrexia, and severe lower limb oedema and a haemorrhagic syndrome. There was a major extensive retroperitoneal haematoma spreading to the perineum. The four limbs were ischaemic. The patient's condition continued to worsen, developing hypoxic pulmonary oedema. He died on the seventh day after the bite, during a session of haemodialysis, from cardiovascular failure resistant to all the usual drugs. The principles of anti-venom therapy are recalled. Indeed, this should be started early enough and relies on large amounts of serum (greater than 50 ml).


[Cardiac herniation and sub-herniation. Complication of intrapericardial pneumonectomy].

Two cases are reported of cardiac herniation complicating intrapericardial pneumonectomy in the early postoperative period. Both patients had a radical pneumonectomy for right-sided bronchial carcinoma invading, in one patient, the carina and the superior vena cava. The pericardial defect, made necessary by the surgical procedure, had not been closed in either patient. About two hours after the end of surgery, both patients, lying supine, developed a state of shock, with tachycardia and arterial hypotension. The diagnosis of cardiac herniation was made in both cases on the chest film. Placing the patient on his left side was only partly efficient in one patient, slowing the heart rate from 160 b.min-1 to 120 b.min-1 and increasing the systolic blood pressure (from 60 mmHg to 80 mmHg). Both patients therefore required to be operated on again. In one patient, the heart had completely herniated through the pericardial defect, and had turned to the right side about the vena caval axis; in the other patient, partly improved by being turned to his left, the heart had returned to its normal position. The pericardial defects were closed in both cases with a strip of dura mater previously treated with 2 (ethyl-mercurithiol-5-benzoxazol) carboxylic acid. The immediate postoperative course was uneventful. Unexpected symptoms and sign occurring in the early postoperative period after intrapericardial pneumonectomy must imperatively lead to carrying out a chest X-ray.


[Propofol versus etomidate in short-time urologic surgery].

Thirty patients, scheduled for short urological surgical procedures and ranked ASA 1 or 2, were randomly assigned to two homogenous groups. In group P, they were given a 2 mg.kg-1 bolus of propofol and 10 micrograms.kg-1 of alfentanil, followed by a continuous infusion of propofol (5 mg.kg-1.h-1) and 5 micrograms.kg-1 doses of alfentanil. In group E, they were given a 0.3 mg.kg-1 bolus of etomidate, followed by an infusion (1.5 mg.kg-1.h-1). The doses of alfentanil were the same as in group P. Further doses of either propofol (0.5 mg.kg-1) or etomidate (0.2 mg.kg-1) were used should anaesthesia prove not to be deep enough. The patients were not intubated, and breathed spontaneously. Surgery lasted a mean of 18.3 +/- 11.8 min (group P) and 18.8 +/- 9.4 min (group E). The following parameters were studied: the amount of each agent required for maintenance of anaesthesia, the duration of apnoea at induction, the quality of anaesthesia and of muscle relaxation, adverse effects (coughing, trismus, restlessness, nausea, vomiting), the time required for recovery, and its quality. In group P, there was a 27% decrease in arterial pressure, without any tachycardia or hypoxia, together with a quick recovery of excellent quality. On the other hand, in group E, there was little or no haemodynamic alteration, but there often was a trismus at induction. Hypoxia also occurred during induction with etomidate, being severe enough in one case to require tracheal intubation and artificial ventilation. The reasons for this hypoxia seemed to be the apnoea and the trismus, which tends to hinder assisted ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)


[Impairment of deglutition reflex after prolonged intubation].

This study was designed to assess the swallowing reflex after an endotracheal intubation of more than 24 h, as well as the influence of age and duration of intubation on swallowing. Twenty patients (aged 58 +/- 17 years) who had been intubated for more than 24 h were compared with fifteen others (63.1 +/- 16.7 years), who had never been intubated. All had a nasogastric tube. Swallowing was assessed after administration of 0.25, 0.5, 0.75 and 1 ml volumes of normal saline, in a random sequence, into the epipharynx through a thin catheter passing through the nostril after extubation (E0), and then at 1 (E1), 8 (E8), 24 (E24) and 48 h (E48) in the extubated patients, and once in the control patients. Swallowing responses were identified by an electromyogram of the floor of the oral cavity. The efficiency of the swallowing reflex was assessed by the delay between instillation and the first swallowing response obtained, and the number of swallows recorded during the first 15 seconds following each injection. There was a significant increase in swallowing delay in intubated patients for volumes less than 1 ml during the first three measurements. Recovery occurred for 0.5 and 0.75 ml at E24 and E48, when compared with the control group. However, delay remained increased throughout the study for 0.25 ml. The number of swallows was the same in both groups for each volume tested. There was no correlation between increased delay and age or duration of intubation. These data confirmed that prolonged endotracheal intubation impairs the swallowing reflex.(ABSTRACT TRUNCATED AT 250 WORDS)


[Analgesic effect of ibuprofen in pain after episiotomy].

The relief of post-episiotomy pain was investigated in three groups of women, ranked ASA 1 or 2, using either a single dose of 400 mg of ibuprofen (n = 31), or 1 g of paracetamol (n = 28) or placebo (n = 31). Pain intensity was assessed with a visual analogic scale, a verbal scale and pain relief scores after half an hour, 1, 2, 3, 4, 5 and 6 h. The day after treatment, patients rated the quality of pain relief, and were asked whether they wished to take again the same drug for the same type of pain. In the placebo and paracetamol groups, respectively 22 and 16 patients asked for usual treatment before the sixth hour, whereas only 5 did so in the ibuprofen group (p less than 0.001). Ibuprofen was more effective after one hour than either of the other two drugs, whatever the scale or parameter used. In the ibuprofen group, the lower pain score was observed at the third hour. At six hours, the pain score did not differ from that three hours earlier. On the day after treatment, 22 patients from the ibuprofen group considered pain relief to have been good or excellent, versus 8 and 5 in the paracetamol and placebo groups respectively (p less than 0.001). Similarly, 24 patients from the ibuprofen group would accept the same drug again for the same type of pain, as opposed to 8 and 5 from the paracetamol and placebo groups respectively (p less than 0.01). The only side-effect reported was abdominal pain in one patient (placebo group).(ABSTRACT TRUNCATED AT 250 WORDS)


[Sedation with propofol and fentanyl in patients under intensive care].

This study investigated the efficacy of a constant rate infusion of propofol and fentanyl in thirty patients requiring artificial ventilation for more than 24 h. A loading dose, which differed according to the patient's age, was administered over a 30 min period: 2.5 mg.kg-1 for patients less than 50 (G1) (n = 9), 2 mg.kg-1 for patients between 50 and 60 years old (G2) (n = 9), and 1.5 mg.kg-1 for patients over 60 (G3) (n = 12). This was followed by an infusion of 3 mg.kg-1.h-1 in G1 and G2, and 2 mg.kg-1.h-1 in G3. A 1 microgram.kg-1.h-1 infusion of fentanyl was also given. The degree of sedation was assessed with the Ramsay scale before starting, after induction, and every four hours thereafter. When this proved to be insufficient, the dose of propofol was increased by 0.5 mg.kg-1.h-1 as well as that of fentanyl by 0.5 microgram.kg-1.h-1. Heart rate, mean arterial blood pressure, blood propofol, creatinine, transaminase and lipid levels, and urine output were measured before, during, and after the infusion. The blood propofol level increased during the infusion, being correlated to the doses given (r = 0.64, p less than 0.001). Sedation lasted 91.7 +/- 57.7 h. After stopping the infusion of propofol, mean recovery times were 7.5 +/- 5.9 min (G1), 11.4 +/- 11.4 min, and 14.4 +/- 13.5 min (G3) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)


[Gastroesophageal reflux with combined caudal and halothane anesthesia in children].

Sixteen children, aged 2 to 5 years and ranked ASA 1, were included in this study assessing gastro-oesophageal reflux occurring under halothane anaesthesia, before and during, caudal anaesthesia. They were scheduled for surgery below the umbilicus lasting 1 to 5 h. After premedication with oral hydroxyzine (2 mg.kg-1) and intravenous atropine (10 micrograms.kg-1), induction was carried out with 3% halothane. A gastro-oesophageal pH probe was inserted via the nose after calibration at 37 degrees C. A neutral pH for the oesophageal electrode and an acid pH for the gastric one demonstrated the correct position of the probe. The pH was then registered every 4 s. The probe was left in situ until the patient left the recovery room. The caudal anaesthesia catheter was then inserted with the patient lying on his left side. Caudal anaesthesia was began with 2.5 mg.kg-1 of plain bupivacaine and 5 mg.kg-1 of plain lidocaine. When the patient was lying supine again, narcosis was maintained with 0.5% halothane and 50% nitrous oxide. A dose of 1.5 mg.kg-1 of bupivacaine was injected every 30 to 45 min. None of the children displayed any respiratory signs (coughing, dyspnoea, bronchospasm, cyanosis) during the combined anaesthetic. Two episodes of asymptomatic gastro-oesophageal reflux were revealed by this method, one lasting 7 minutes and occurring during insertion of the caudal catheter, and the other, lasting 4 minutes, during recovery. There were no pulmonary sequels. There was excellent respiratory and haemodynamic stability throughout. The two episodes seemed to have been triggered off by rapid displacement of the patient and too deep an anaesthetic.(ABSTRACT TRUNCATED AT 250 WORDS)


[Effects of halogenated anesthetics on splanchnic hemodynamic in normo- and hypovolemic cirrhotic rats].

The effects of 1 MAC of either halothane, enflurane or isoflurane on splanchnic haemodynamics were studied in cirrhotic rats that were either normovolaemic or hypovolaemic from haemorrhage. A group of conscious rats acted as the control group. Bile duct ligation had been carried out in all the rats four weeks previously to induce cirrhosis. At the time of the study, all the rats were anaesthetized with ether for catheterization of the left femoral artery and vein, and the left ventricle via the right carotid. The control group was allowed to awake. When the other rats started to recover, they were artificially ventilated with room air and 1 MAC of the halogenated agent. Heart rate and mean arterial blood pressure were monitored continuously. Once the animals had remained steady for one hour, 1.25 ml of blood for 100 g body weight was removed over a 10 min period. PaO2, PaCO2, arterial pH, heart rate, mean arterial blood pressure, cardiac index and regional blood flows (RBF) were measured before, and thirty minutes after the haemorrhage. Cardiac output and RBF were measured using the radioactive-labelled microsphere method. Only 32 animals were finally included, eight in each group. Splanchnic, portal and hepatic arterial blood flows were similar in conscious rats and in those receiving isoflurane or halothane, and were higher than in those receiving enflurane. The lowest splanchnic and portal venous blood flows were found in those rats receiving enflurane. After haemorrhage, these RBF decreased significantly in all groups except in the enflurane group.(ABSTRACT TRUNCATED AT 250 WORDS)


[Monochromatic infrared halogenated gas analyzer and handling errors].

Monochromatic infrared gas spectrometers cannot identify volatile agents. Such an analyser (Capnomac, Datex) was tested while performing two errors: a) erroneous selection of the agent on the analyser, the vaporizer being filled with the correct agent; b) total or partial filling of the vaporizer (Vapor 19, Dräger) with an incorrect agent, the analyser being set for the agent the vaporizer was specified for. Three agents were studied, halothane (H), enflurane (E) and isoflurane (I). Each experiment was made in triplicate, the vaporizer being dried out between each. In case of erroneous selection on the analyser, differences between E and I were very small. When H was erroneously selected, the concentration displayed was six times higher, and when E or I was selected instead of H, the concentration displayed was six times lower than expected. In the 3.3-3.5 m band, H transmittance was six times higher than those of E and I. The agent selection control changes the gain so as to correct for the selected agent (gain for H: 12.0, E: 2.24, I: 1.89). In case of erroneous filling of the vaporizer, the concentration displayed was always different from that expected. When E or I was delivered with an H vaporizer, the analyser being set on H, the concentration displayed was 3 to 9 times higher than the concentration that had been set. On the other hand, when H was delivered with an E or I vaporizer, the analyser being set to E or I, the concentration displayed was 4 to 8 times lower.(ABSTRACT TRUNCATED AT 250 WORDS)


[Desflurane (I 653) and sevoflurane: halogenated anesthetics of the future?].

Sevoflurane is an halogenated methyl isopropyl ether. It is potent, non explosive and non flammable. It reacts with soda lime to form traces of a related ether which has not been shown to have any toxic effect on animals chronically exposed to it in a closed system. Induction of anaesthesia with sevoflurane is rapid and smooth, as predicted by a blood/gas partition coefficient of about 0.6 and an acceptable odour which allows the use of concentrations of up to 10%. Its MAC has been reported to vary between 1.7 and 2.3 vol %. Sevoflurane causes dose-dependent cardiovascular and respiratory depression. Its effect on the cerebral circulation is similar to that of isoflurane. The extent of biotransformation is similar to that of enflurane, but its low solubility and rapid elimination confine this to the period of inhalation. No toxic effects on the kidneys, liver and haematopoietic system have been found. Desflurane is a fluorinated methyl ether, structurally very similar to isoflurane. It is non flammable and non explosive at clinical concentrations. It is more stable in the presence of soda lime than any of the volatile anaesthetic agents available. This agent must be delivered with a thermostated vaporizer within a closed circle system, as its boiling point is 23.5 degrees C. Desflurane is less potent than isoflurane. Its MAC has been estimated to be about 7.2 vol % in man. Desflurane did not lead to any liver, lung or kidney injury in laboratory rats, even during hypoxia and enzyme induction. Desflurane undergoes little biotransformation, although the presence of volatile metabolites or covalent tissue-bound products cannot be excluded.(ABSTRACT TRUNCATED AT 250 WORDS)


[Is posterior lumbar epidural space partitioned?].

The anatomy of the posterior lumbar epidural space (PLES) has been extensively studied. Besides the anatomists, surgeons, radiologists and anaesthetists have taken an interest in this. However, because each one has considered the PLES from his own specialist field, descriptions are not always concordant. In particular, the reality of a medial partition in the PLES has been suggested by epidurography and intraoperative observations. Lewit and Sereghy and Luyendijk opened the debate by reporting, on antero-posterior epidurographic films, a clear-cut, medial, vertical and narrow picture which partitioned the PLES. However, this was not constant. Savolaine et al. also recognized this partition on epidurographic CT scans. During laminectomies, Luyendijk has taken photographs of a medial fold of the dura mater which appeared to hold it to the posterior vertebral arch, being collapsed on either side of the midline. He named it "plica mediana dorsalis durae matris" (PMD). Several anaesthetists considered that this could explain why epidural analgesia sometimes acted on one side only. Husemeyer and White, and Harrison et al., have tried to confirm this experimentally by making casts with polymerizing resins in cadavers. They did not get very convincing results. Blomberg also tried to see this space by epiduroscopy in the cadaver. Unfortunately, for technical reasons, his photographs were of poor quality. He, however, reported having seen each time the PMD and a band of connective tissue fixing it to the vertebral arch in the midline. However, all these anatomical studies used methods which alter the natural structures. Their results are therefore questionable. The PLES is a virtual space. Histological studies have shown that it is filled with fatty tissue between the dura and the vertebral arch. It is therefore conceivable that any liquid injected into the PLES, such as contrast medium or local anaesthetic, must push back the dura, the only tissue which can move to give it any room. The fatty tissue could therefore be compressed and take any of the shapes which have been described on epidurography. On the other hand, should it be torn, it seems this fatty tissue could make up these haphazard fibrous tracts tensed between the dura and the vertebral arch, such as described in classical anatomy, as Bonica recalled. These can be clearly seen during surgical and anatomical dissections, and during endoscopies carried out on cadavers with sufficient optical means, as opposed to the medial fibrous band fixing the dura to the vertebral arch.(ABSTRACT TRUNCATED AT 400 WORDS)


[Vascular effects of ketamine during anesthesia with diazepam and fentanyl].

Twenty-six adults undergoing elective cardiac surgery were anaesthetized with diazepam and fentanyl (induction with 200 micrograms.kg-1 and 30 micrograms.kg-1 respectively, maintenance with incremental doses). Normothermic constant perfusion output cardiopulmonary bypass was carried out with a membrane oxygenator, haemodilution with Ringer's lactate solution, and cardioplegia with St. Thomas's Hospital solution. The patients were randomly assigned to two groups. They were given either 2 mg.kg-1 of ketamine (group 1) or placebo (5 ml of normal saline) (group 2) via the venous line of the oxygenator. The non pulsatile flow was then kept at a steady rate of 2.41 x min-1.m-2, and no other infusion or treatment was started during the study period (ten minutes). The mean arterial pressure and blood reservoir level were measured every min during this period. The systemic vascular resistances did not change significantly in either group, but remained 27% lower in the ketamine group than in the placebo group (p less than 0.01). The blood reservoir level was 37% higher in the ketamine group (p less than 0.01), suggesting a decreased venous capacitance. It is therefore concluded that ketamine leads to venous constriction, and probably arterial dilation, during fentanyl-diazepam anaesthesia and normothermic cardiopulmonary bypass. The venous effects of ketamine could explain why it is usually well tolerated in hypovolaemic states.


[Penile block in adults].

A block of the penile nerves provides a sensory blockade of the penis. In adults, surgery can thus be carried out on the foreskin, glans, corpus cavernosum, corpus spongiosum or penile urethra. The two dorsal nerves of the penis can be blocked by two different routes. In the median technique, only one injection is performed in the subpubic space, near the posterior inferior aspect of the symphysis. In the bilateral technique, each penile nerve is blocked separately at the level of the penile root. Whichever technique is used, additional subcutaneous infiltration of the penile root improves the quality of analgesia. Bupivacaine without adrenaline is used at a concentration of 0.25% or 0.5%. In the median technique, bilateral diffusion of the anaesthetic solution has been demonstrated in ten patients by adding contrast medium to the anaesthetic solution. On the other hand, contralateral diffusion was only found in six of ten patients after an unilateral injection. These results substantiate the value of the bilateral technique in the adult. Both techniques were used in a group of 80 patients, aged 17 to 87 years. In 47 patients no other agent was administered, while the remaining 33 had either additional sedation or a general anaesthetic. Among the latter, three had a partial failure of the block. Postoperative analgesia, which was of excellent quality, covered an average of 10 hours. Neither local nor general incident occurred. Penile block is a reliable technique for regional anaesthesia. Because it is easy to carry out, and comfortable for the patient, this technique may be suggested to adults requiring penile surgery.


[Is preoperative systematic chest x-ray useful in general surgery? A multicenter prospective study of 3959 patients. ACAPEM. Association des Chirurgiens de l'Assistance Publique pour les Evaluations Médicales].

In order to define which patients may not require a routine preoperative chest X-ray, a prospective multicenter study was carried out. It included 3,959 consecutive fifteen, or more, year-old patients, free from any cancer, scheduled for a general or gastrointestinal surgical procedure other than thoracotomy, and had a plain chest X-ray beforehand. This investigation was prescribed before surgery, either by the surgeon or the anaesthetist. Patients were classified according to selected risk factors: age, smoking, emergency surgery, a past history of lung, heart or vascular disease, abnormal clinical findings related to the cardiovascular and respiratory systems, and a previous chest film made less than one year before. There were 2,092 patients in Group I (no risk factors), 916 in group II (one risk factor), 645 in Group III (two risk factors), and 276 in group IV (three risk factors). Three endpoints were selected: a modification of operative schedule or anaesthetic technique, a change in surgical procedure, and the diagnosis of postoperative complications. A rate of 23.2% of preoperative chest films were considered to be abnormal. This rate increased with age and the number of risk factors: 6.2% in Group I and 72.5% in Group IV. Surgical and anaesthetic procedures were modified as a result of the chest X-ray in only 0.5% of patients: 0.1% in Group I, 0.3% in Group II, 1.2% in Group III and 1.4% in Group IV. When pulmonary or cardiac complications did occur after the surgery, the preoperative chest film was of no help for making this diagnosis in more than 50% of cases.(ABSTRACT TRUNCATED AT 250 WORDS)


[Disclosure of protein C deficiency with pulmonary embolism followed by cardiac arrest during the recovery period].

A case of unexpected cardiac arrest occurring in a 17-year-old male patient is reported. The patient had been admitted after sustaining hand trauma. A first emergency surgical procedure was carried out, followed about three weeks later by another one. No incidents occurred during or after either of these two operations. A third procedure was required about two months after the accident (free toe graft to the thumb of the left hand). The twelve-hour operation was carried out under general anaesthesia and axillary block. The patient was given intravenous heparin (800 IU.h-1) during the procedure on the arm. The patient recovered quickly, and was extubated before his transfer to the recovery room. Fifteen minutes later, the patient's heart rate decreased to 40 b.min-1, followed by a transient cardiorespiratory arrest. The suspicion of pulmonary embolism was confirmed by pulmonary scintigraphy. Thrombolysis was carried out with 2,000 IU.kg-1.h-1 of urokinase for a 72 h period, combined with continuous heparin administration (16 to 36 x 10(3) IU.day-1). The patient recovered after one week. No thrombophlebitis was found for origin of the emboli. Biological investigations carried out both before and after 10 minutes of anoxia revealed a normal fibrinolytic system, but a deficit in protein C (62% antigen, 64% activity). Two years after the episode of pulmonary embolism, the patient, still taking acenocoumarol, remained free from any sequela. Current perioperative management of patients with a known protein C deficit is discussed.


A brief history of bioelectrodes.

The history of bioelectrodes is intimately associated with electrochemistry in general, through studies on electrode polarization. Electrode polarization was first recognized and studied in the early 1800s, and scientific studies in this area have continued since that time. Experimental and theoretical work on bioelectrodes, electrode polarization, and relevant electrochemistry of electrode phenomena, is traced from 1826 to Schwan's recent electrode work.


Linear and nonlinear electrode polarization and biological materials.

Electrode polarization is a major nuisance while determining dielectric properties of cell and particle suspensions and tissues, particularly at low frequencies. Understanding of these interfacial phenomena and appropriate modelling are essential in order to correct for its distortion of the dielectric properties of the sample of interest. I survey the following topics, concentrating on contributions from our laboratory: Linear properties of electrode polarization and relevant models. Effects of electrode polarization on sample impedance. Effects of sample on polarization impedance. Techniques of correction. Extension of linear to nonlinear models Harmonics generated in the nonlinear range.


Impedance spectroscopy.

Impedance spectroscopy (IS) is a general term that subsumes the small-signal measurement of the linear electrical response of a material of interest (including electrode effects) and the subsequent analysis of the response to yield useful information about the physicochemical properties of the system. Analysis is generally carried out in the frequency domain, although measurements are sometimes made in the time domain and then Fourier transformed to the frequency domain. IS is by no means limited to the measurement and analysis of data at the impedance level (e.g., impedance vs. frequency) but may involve any of the four basic immittance levels: thus, most generally, IS stands for immittance spectroscopy.


A physical interpretation of Schwan's limit current of linearity.

In this the second of a series of papers on the nonlinearity of the electrode-electrolyte interface impedance, the wealth of experimental observations which exists in the literature on AC impedance nonlinearity is physically interpreted. The interface impedance is well represented by the parallel combination of a constant phase angle impedance and a charge transfer resistance. The charge transfer resistance is the major source of the observed nonlinearities. As a result, the current limit of linearity, iL, increases with frequency such that iL is proportional to omega beta. The series resistance, Rs, of the interface impedance initially increases with applied signal amplitude, reaches a maximum and then decreases. The series reactance, Xs, decreases monotonically with signal amplitude.


Analysis of polarization dynamics by singularity decomposition method.

The driving point immittance (impedance or admittance) function is commonly used in electrical characterization of polarized materials and interfaces. The immittance function typically attenuates following a power function dependence on frequency. This fact has been recognized as a macroscopic dynamical property manifested by strongly interacting dielectric, viscoelastic and magnetic materials and interfaces between different conducting substances. Linear interfacial polarization processes which occur at metal electrode-electrolyte interfaces have been represented by the Fractional Power Pole [FPP] function in single or multiple stages. The FPP function is referred to as the Davidson-Cole function in the dielectrics literature. A related function widely used in mathematical modeling of dielectric and viscoelastic polarization dynamics is the Cole-Cole function. The fractional power factor which parametrizes the FPP or the Davidson-Cole function has been shown earlier to equal the logarithmic ratio of the locations of the pole-zero singularities. In this paper we first review a modified form of the singularity decomposition of the FPP function accomplished within a prescribed error range. The distribution spectrum and the corresponding simulation by a cascade R-C network, as opposed to the synthesis by a ladder R-C network, are readily obtained as the next step in the simulation. The method is then applied to decompose the Cole-Cole function; the pole-zero placement of the singularity function is determined and the equivalent cascade R-C network is synthesized.


The admittance of the interface between a metal electrode and an aqueous electrolyte solution: some problems and pitfalls.

Electrochemical admittance measurements have become popular as a convenient, non-invasive method for the study of interfacial properties of the metal-solution interface. However, uncritical use of this technique (as of any other) can lead one astray. Here, then, some of the complicating factors and common problems will be discussed.


Electrode-electrolyte interface impedance: experiments and model.

The impedance of the junction between a solid or aqueous electrolyte and a metal electrode at which no charge transfer processes occur (blocking contacts) follows closely the constant phase angle form, Z = A(j omega)-n, over a wide frequency range, where A is a constant, and the frequency exponent n is typically in the range of 0.7 to 0.95. Several models have been proposed in which the magnitude of the frequency exponent n is related by a simple expression to the fractal dimension d of the rough electrode surface. But experiments with aqueous H2SO4 and roughened platinum and silicon electrodes show that there is no simple relationship, if any at all, between n and d when d is determined from the analysis of one dimensional surface profiles. Moreover, n is not a simple function of the average roughness of the electrode. In order to gain some insight into the effect of electrode topography and the interface impedance, a model for the response of the interface to a constant voltage pulse was constructed. This model is based on the idea that, following a pulse, locally concentrated regions of ions accumulate rapidly at the tips of large protrusions on the electrode surface which screens deeper regions of the electrode from the field driven flux of mobile ions. After this rapid charging, ions are able to reach the deeper, screened regions of the electrode by diffusion, and it is this diffusive process that gives rise to the observed t1-n dependence of the charge collected. Computer simulations, similar to the diffusion limited aggregation model, using measured profiles as fixed (non-growing) clusters, gave exponents n in good agreement with experiment.


Impedances of thin and layered systems: cells with even or odd numbers of interfaces.

Impedance data, e.g., system responses, from perturbing small amplitude applied sinusoid signals of near DC to high kilohertz frequencies, give chemical information. Analysis of frequency-dependent imaginary and real impedance proceeds from equivalent analog circuit elements to chemical and physical significance determined from many model systems. Already, it is possible to interpret bulk transport processes, surface kinetic effects, diffusion phenomena, and dependencies on the type of contacts: symmetric ion contact, symmetric metal contact or asymmetric metal-ion interfaces, and cell design; even (battery or sensor) and odd numbered (constrained junction or immiscible liquid) interfaces in a system. These analyses cover the chemical origins, locations and meanings of the lumped resistances, capacitances and transmission lines that are introduced by engineers in their strict analog interpretations of the impedance data. Examples cover simple ohmic, simple diffusive behavior, complex behavior with surface interfacial kinetics or surface resistances, and with finite (nonblocking) or infinite (blocking) DC impedance. High and low frequency responses may show so-called constant phase element character that suggests fractal behavior. Low frequency data occasionally appear in the second quadrant of impedance plane plots. These results are caused by negative capacitances and resistances. In this paper, chemical interpretations of analog circuit elements are mainly based on theory and observations of thin cells of electrolytes and solid and liquid films (membranes) that are ionic or mixed ionic/electronic conductors. The information should carry over into thickened, gelled, and tissue electrolyte phases and serve as a basis for medically-oriented, perhaps diagnostic impedance measurement applications already pioneered by Herman Schwan.


Electrode recovery potential.

In some instances the same electrodes are used for stimulation and then for recording a bioelectric event immediately after the stimulus. However, after the current pulse there remains an electrode potential that decays quasiexponentially. We have designated this falling potential the electrode-recovery potential. This study investigated the recovery potentials of single electrodes of rhodium, stainless steel, platinum and platinum-iridium in contact with 0.9% saline at room temperature (25 degrees C) over a current density ranging from 0.1 to 100 mA/cm2 using a constant-current pulse. In all cases, with increasing current density, there was a decrease in the time for the electrode potential to fall to one half of the immediate post-stimulus value. Above about 20 mA/cm2 the decrease in recovery time was smooth with increasing current density. Below 20 mA/cm2, the recovery time was slightly irregular. The shortest recovery times were for platinum and platinum-iridium. The largest decrease in recovery time with increasing current density was for stainless steel, which decreased 10 fold from 0.1 to 100 mA/cm2. The recovery time for rhodium decreased about three-and-one half fold over the same current density range. It was found that the waveform of the recovery potential is not a simple exponential because the Warburg and Faradic components of the electrode-electrolyte interface are current-density dependent. In general, for all current densities studied (0.1-100 mA/cm2), there was a sudden initial fall in electrode potential with cessation of current flow, followed by a very gradual nonexponential decrease in potential.


Biocompatibility considerations at stimulating electrode interfaces.

The choice of biocompatible stimulating electrodes for various biomedical applications varies with the type of electrode-tissue interface, biomolecules present, electrolyte background, preparation of electrode, interfacial potential, current density, electrode material, porosity, geometry, and inflammatory response. Illustrative examples are given to demonstrate the importance of these parameters. Topics discussed are: A) DC electrodes applied to partially keratinized epithelial membranes; B) Variation of the electrical impedance and biocompatibility of stimulating electrodes with electrode potential and surrounding pH; C) Influence of electrode geometry, porosity and pore size on biocompatibility; D) Body defense mechanisms at the sites of implantable stimulating electrodes; E) Thrombus formation at stimulating electrode interfaces and F) Sterilization of electrodes to ensure biocompatibility.


Utility of serum interleukin-6 for diagnosis of invasive bacterial disease in children.

To evaluate measurement of interleukin-6 as a diagnostic test for the presence and severity of invasive bacterial disease. Prospective measurement of interleukin-6 in children with signs of sepsis. (Controls, retrospective from serum bank.) Emergency department of an urban children's hospital. Twenty children with clinical signs of sepsis and 50 other febrile infants and toddlers with negative blood cultures. Eleven of the 20 patients had bacteriologically documented infections: four with meningitis and two with bacteremia caused by Neisseria meningitidis, three with meningitis caused by Haemophilus influenzae type b, and one each with meningitis and bacteremia caused by Streptococcus pneumoniae. Ten of these 11 had detectable interleukin-6. The geometric mean interleukin-6 level in these culture-positive patients was 407 pg/mL (95% confidence interval, 108 to 1,545); all three children with levels of more than 300 pg/mL developed septic shock, and one died. One of nine culture-negative patients with clinical signs of sepsis had detectable serum interleukin-6 (166 pg/mL), but none of 50 other febrile children without occult bacteremia did. The detection of interleukin-6 had a sensitivity of 91% and a specificity of 98% for invasive bacterial disease. High levels of interleukin-6 occur in children with septic shock, and the presence of interleukin-6 in serum is predictive for the isolation of bacteria from blood and/or spinal fluid.


Septic arthritis versus transient synovitis of the hip: the value of screening laboratory tests.

To determine the diagnostic value of screening laboratory and initial body temperature data in differentiating septic arthritis of the hip from transient synovitis of the hip in children who present to the emergency department with a complaint of hip pain. Retrospective review of cases of septic arthritis of the hip and transient synovitis of the hip in a 1:2.5 ratio. An urban regional children's hospital with 20,000 annual ED visits. Ninety-four children with transient synovitis of the hip and 38 children with septic arthritis of the hip were identified. The children with septic arthritis of the hip had a significantly higher initial temperature (38.1 C versus 37.2 C, P = .000014), mean erythrocyte sedimentation rate (44 mm/hr versus 19 mm/hr, P = .000001), and mean WBC count (13,200/mm3 versus 11,200/mm3, P = .02). However, the degree of overlap in these variables was large. The combination of an erythrocyte sedimentation rate of more than 20 mm/hr and/or a temperature of more than 37.5 C identified 97% of all cases of septic arthritis of the hip. There is clinically significant overlap in the erythrocyte sedimentation rate, temperature, and WBC count in children with septic arthritis of the hip versus transient synovitis of the hip. All children with an irritable hip without a clearly identified source who have an erythrocyte sedimentation rate of more than 20 mm/hr or a temperature of more than 37.5 C should be considered for diagnostic hip aspiration.


Plain abdominal radiography in the detection of major disease in children: a prospective analysis.

To prospectively evaluate previously described high-yield clinical criteria for obtaining plain abdominal radiographs in the emergency evaluation of children. Prospective, observational study. Emergency departments of a university medical center and an affiliated county hospital. Three hundred fifty-four children 15 years old or younger who underwent plain abdominal radiography during a one-year period. Physicians ordering plain abdominal radiographs completed data forms that included historical and physical examination information before viewing films. At a later date, records of all patients were reviewed for radiologist interpretation and final diagnosis. The data were analyzed to determine the sensitivity, specificity, and predictive values of previously described high-yield criteria (from a retrospective series) in detecting radiographs that were diagnostic or suggestive of "major" abdominal disease. Sixty-one patients (17%) had major diseases potentially requiring procedural intervention (eg, appendicitis, ingested foreign bodies, and intussusception), whereas 296 patients (83%) had minor diseases not requiring procedural intervention (eg, gastroenteritis and nonabdominal diagnoses). The presence of any of the following features--prior abdominal surgery, foreign body ingestion, abnormal bowel sounds, abdominal distention, or peritoneal signs--was 93% sensitive and 40% specific in detecting diagnostic or suggestive radiographs in patients with major disease. Positive and negative predictive values were 11% and 99%, respectively. If only these criteria had been used to obtain radiographs, 38% of films would have been omitted (at an estimated savings of $20,000) with only two suggestive radiographs missed. Our results suggest that restricting abdominal radiographs to patients with at least one of these five high-yield clinical features will detect most diagnostic and suggestive radiographs in children with major abdominal diseases.


Prehospital intravenous access in children.

To examine the ability of a unified metropolitan paramedic system to provide IV access in children when indicated. Retrospective, descriptive clinical study. A large metropolitan area in Canada. Five hundred thirteen children from birth through 18 years of age who were transported by paramedics. Indications for IV access, rates of successful placement, and time to achieve access were determined. Criteria for IV line placement were developed and applied retrospectively. Intravenous line attempts were made in 300 children (58%). Intravenous line placement was obtained in 253 (84% of the patients attempted). One hundred fifty-nine children met criteria for IV placement in the field. Six of these children were clinically dead and received no on-scene resuscitative efforts and were excluded from data analysis. Of the remaining 153 children who met criteria, 122 (80%) had IV attempts made, and 104 (68%) had an IV line placed successfully. For children who met the criteria for IV placement, a significantly smaller proportion of children younger than 6 years had an IV line placed successfully (49%) compared with children 6 years or older (75%) (P < .005). Two subgroups of children who met criteria were examined: children with vital signs absent and trauma patients. For those who belonged to the subgroup with vital signs absent, a significantly smaller proportion of children younger than 6 years had an IV line placed successfully (43%) compared with children 6 years or older (92%) (P < .01) Eighty-four percent of patients who met criteria and who had one IV line successfully placed received only one IV line attempt, and 87% of patients who met criteria and who had two IV lines placed successfully received only two attempts. Although paramedics had an 84% success rate at establishing IV lines in children in the field, half the children younger than 6 years who required intravascular access did not receive an IV line in the prehospital setting. Multiple IV line attempts should be discouraged because additional attempts yield little benefit and may prolong transport times.


Adrenaline-cocaine gel topical anesthetic for dermal laceration repair in children.

To evaluate the anesthetic efficacy of a gel form of adrenaline-cocaine topical medication for minor dermal laceration repair. Unblinded, prospective. An urban pediatric emergency department. Thirty-five children aged 20 months to 18 years with lacerations of the face, outer lip, and scalp. All received adrenaline-cocaine gel made by mixing 1.5 mL of conventional adrenaline-cocaine liquid (adrenaline, 1:2,000; cocaine, 11.8%) with 0.15 g of methylcellulose powder (an inert emulsifying agent). Lacerations were located on the face or outer lip in 25 patients and on the scalp in ten patients. Larger lacerations (length of more than 5 cm and/or depth of more than 5 mm) occurred in nine patients. The average dose of adrenaline-cocaine gel applied per laceration was 0.35 mL (containing 40 mg cocaine). One hundred ninety-five sutures were placed (175 cutaneous, 20 subcutaneous); 192 (98.5%) were placed without eliciting any pain. There were no observed adverse reactions with adrenaline-cocaine gel administration or reported complications of wound healing in any patient. Adrenaline-cocaine gel preparation provides excellent anesthetic efficacy for minor dermal lacerations in children. Compared with conventional adrenaline-cocaine liquid, adrenaline-cocaine gel may be advantageous in reducing the total cocaine requirement and may diminish the risk for adverse reactions that can result from runoff of liquid medication onto mucosal or ocular surfaces.


Analysis of the clinical variables driving decision in an artificial neural network trained to identify the presence of myocardial infarction.

To determine which clinical variables drive the output of an artificial neural network trained to identify the presence of myocardial infarction. Partial output analysis. Tertiary university teaching center. Seven hundred six patients more than 18 years old presenting with anterior chest pain. Differential network output analysis. A methodology was developed as the first step in measuring the impact input clinical variables have on the output (diagnosis) of an artificial neural network trained to identify the presence of acute myocardial infarction. The methodology revealed that the network used the presence of ECG findings, as well as the presence of rales, syncope, jugular venous distension, response to trinitroglycerin, and nausea and vomiting, as major predictive sources. Although this first-step analysis studied individual variables, it must be stated that the network comes to clinical closure based on the settings of all variables in a pattern and that the impact of a single variable cannot be taken out of the context of a pattern. An artificial neural network trained to recognize the presence of myocardial infarction appears to place diagnostic importance on clinical variables that have not been shown previously to be highly predictive for infarction.


Serial ECGs are less accurate than serial CK-MB results for emergency department diagnosis of myocardial infarction.

Serial creatine kinase-MB (CK-MB) levels provide more accurate predictive information regarding myocardial infarction than serial ECGs in emergency department patients with chest discomfort and no ST-segment elevation on the initial ECG. Prospective, observational study. University hospital and university-affiliated Veterans Affairs Medical Center EDs. Two hundred sixty-one patients 30 years or older with chest discomfort warranting an ECG and consenting to observation. Exclusions included hemodynamic or rhythm instability and ST-segment elevation of 0.1 mV or more in two or more electrically contiguous leads at presentation. ECGs were obtained at presentation and three to four hours after presentation. Significant serial ECG changes sought on comparison of initial and three- to four-hour ECGs were 0.05 mV or more ST elevation or depression, Q-wave development, or T-wave inversion changes in two or more electrically contiguous leads. CK-MB levels were obtained at presentation and hourly for three hours (positive level, 8 or more ng/mL). Myocardial infarction was determined by record review and was based on independent CK-MB measurements. Twenty-eight (11%) patients were diagnosed with a myocardial infarction. Thirty-eight (15%) patients had a serial ECG change. Eleven of the myocardial infarction patients (39%) had a serial ECG change compared with 27 (12%) of the non-myocardial infarction patients (P < .001). Sensitivities and specificities of a serial ECG change versus serial CK-MBs for myocardial infarction were 39% versus 68% (sensitivity) and 88% versus 95% (specificity), respectively. Serial CK-MBs were more accurate than a serial ECG change for predicting myocardial infarction (P < .03). Serial changes in ECGs during a three- to four-hour interval were associated with the diagnosis of myocardial infarction but were infrequent and less accurate than serial CK-MB levels obtained for the same interval.


Efficacy and safety of transcutaneous low-impedance cardiac pacing in human volunteers using conventional polymeric defibrillation pads.

To assess the safety and efficacy of transcutaneous cardiac pacing using low-impedance defibrillation-type, self-adhesive polymer electrode pads positioned in the same anatomic sites typical of such pad placement in emergency defibrillation attempts. Prospective, randomized, single-blinded normal subject investigation. Thirty healthy unmedicated adult volunteers of both sexes were paced transcutaneously to the threshold of capture and beyond by an intensity factor of 125%. A commercial defibrillator-pacer operating in demand mode had its rate set-point higher than the subjects' base-line rate by 125%. Threshold was established as the pulse current required to effect 75% captured beats. Pacing was continued at the 125% level for two minutes, during which subjective discomfort levels were recorded on a 1-to-5 pain scale. All subjects but one were able to complete the study as designed. The single exception complained of intolerable pain early in the two-minute trial. Capture current had a mean value of 80 mA while the pain assessment averaged 3.2 on our five-point scale. No subject showed any untoward cardiovascular effects either during or after the study. In normal human volunteers, transcutaneous cardiac pacing with low-impedance polymer pad electrodes is safe. By extrapolation from this study population, it is sufficiently effective to accommodate successfully the vast majority of clinical circumstances likely to be encountered in emergency medicine.


Low-risk criteria for cervical-spine radiography in blunt trauma: a prospective study.

Cervical-spine radiography does not need to be performed on selected blunt trauma patients who are awake, alert, nonintoxicated, do not complain of midline neck pain, and have no tenderness over the bony cervical spine. One thousand consecutive patients seen in the UCLA Emergency Medicine Center with a chief complaint of blunt trauma, for whom cervical-spine films were ordered and for whom prospective data questionnaires were completed. Clinicians completed data forms for each patient before radiograph results were known. Data items included mechanism of injury, evidence of intoxication, presence of cervical-spine pain and/or tenderness, level of alertness, presence of focal neurologic deficits, and presence of other severely painful injuries unrelated to the cervical spine. Physicians were also asked to estimate likelihood of significant cervical-spine injury. Twenty-seven patients with cervical-spine fracture were among the 974 patients for whom data forms were completed. A number of findings were statistically more common in the group of patients with fracture than without, but no single or paired findings identified all patients with fracture. All 27 patients with fracture had at least one of the following four characteristics: midline neck tenderness, evidence of intoxication, altered level of alertness, or a severely painful injury elsewhere. Three hundred fifty-three of 947 (37.3%) patients without cervical-spine fracture had none of these findings. Cervical-spine radiology may not be necessary in patients without spinous tenderness in the neck, intoxication, altered level of alertness, or other severely painful injury. A policy to limit films in such patients would have decreased film ordering by more than one third in this series, while identifying all patients with fracture.


Incidence of agonal respirations in sudden cardiac arrest.

To discover the frequency of agonal respirations in cardiac arrest calls, the ways callers describe them, and discharge rates associated with agonal respirations. We reviewed taped recordings of calls reporting cardiac arrests and emergency medical technician and paramedic incident reports for 1991. Arrests after arrival of emergency medical services were excluded. King County, Washington, excluding the city of Seattle. Four hundred forty-five persons with out-of-hospital cardiac arrests receiving emergency medical services. Telephone CPR, emergency medical technicians-defibrillation, and advanced life support by paramedics. Any attempts at breathing described by callers were identified, as well as whether agonal respirations could be heard by dispatcher, emergency medical technicians, or paramedics. Agonal respirations occurred in 40% of 445 out-of-hospital cardiac arrests. Callers described agonal breathing in a variety of ways. Agonal respirations were present in 46% of arrests caused by cardiac etiology compared with 32% in other etiologies (P < .01). Fifty-five percent of witnessed arrests had agonal activity compared with 16% of unwitnessed arrests (P < .001). Agonal respirations occurred in 56% of arrests with a rhythm of ventricular fibrillation compared with 34% of cases with a nonventricular fibrillation rhythm (P < .001). Twenty-seven percent of patients with agonal respirations were discharged alive compared with 9% without them (P < .001). There is a high incidence of agonal activity associated with out-of-hospital cardiac arrest. Presence of agonal respirations is associated with increased survival. These findings have implications for public CPR training programs and emergency dispatcher telephone CPR programs.


Prevention of hyperbaric-associated middle ear barotrauma.

To determine the efficacy of topical nasal decongestant in the prevention of middle ear barotrauma in patients undergoing hyperbaric oxygen therapy. Prospective, parallel, double-blind, randomized trial. University-affiliated community hospital emergency department with hyperbaric oxygen facilities. Sixty patients undergoing hyperbaric oxygen therapy; 30 subjects in each treatment arm. After randomization, consenting patients were given two sprays of oxymetazoline hydrochloride or sterile water, 15 minutes before hyperbaric oxygen therapy. Collected data included patient demographics, ear examinations before and after hyperbaric oxygen treatment, and subjective ear complaints. The otoscopic appearance of the tympanic membrane was graded according to the amount of hemorrhage in the eardrum, with Teed scores ranging from 0 (symptoms only) to 5 (gross hemorrhage and rupture). The treatment groups were similar with regard to age, sex, and medical history. Ear discomfort during hyperbaric oxygen therapy was present in 63% (19 of 30) of those receiving oxymetazoline versus 67% (20 of 30) of the control group (P = .99). Likewise, both groups had similar Teed scores after hyperbaric oxygen therapy (P = .88). No adverse effects were noted. The results of this pilot study suggest that topical decongestants may not be effective in preventing middle ear barotrauma during hyperbaric oxygen therapy.


Use of transcutaneous electrical nerve stimulation for fingertip analgesia: a pilot study.

To determine if transcutaneous electrical nerve stimulation (TENS) can produce fingertip analgesia. Randomized, crossover trial. Fifteen healthy volunteers, naive to the technique of TENS. TENS stimulation was applied to the middle and ring fingers of each subject's hands by means of small carbon electrodes placed over the digital nerves. Patients received one fingertip puncture from a mechanically driven sterile lancet device to each digit corresponding to one of four conditions: sham, one minute of TENS, ten minutes of TENS, and 20 minutes of TENS. The TENS unit was operated in the "burst" mode, with two eight-pulse burst groups per second (pulse width, 225 mu sec; pulse frequency, 80 Hz). The order of the conditions and the finger used for each condition were assigned randomly. The pain of each puncture was rated on a 10-cm visual-analog scale. Data were analyzed using a repeated-measures analysis of variance with Duncan's multiple comparisons procedure. Mean visual-analog scale scores decreased sequentially from sham in each experimental condition: one minute of TENS, 24.4% (P < .025); ten minutes of TENS, 28.2% (P < .025); and 20 minutes of TENS, 55.7% (P < 10(-6)). Two patients had total anesthesia of the fingertip (visual-analog scale = 0 cm) in the 20-minute TENS condition. TENS significantly reduces the pain of lancet-induced trauma to the fingertip. Further studies are warranted to determine if this technique is useful clinically as an alternative or adjunct to digital nerve block anesthesia for fingertip surgical procedures.


Shipboard medicine: a new niche for emergency medicine.

To describe the spectrum of illness that presents to shipboard hospitals and thereby recommend optimal qualifications for the ship's medical personnel. Retrospective review of medical logs from two cruise ships' hospitals. Two passenger cruise ships, with seven-to-ten day cruises in the Caribbean. All patients presenting to the ships' hospitals from January 4, 1989, to June 10, 1989, on one ship and from October 13, 1990, to November 10, 1990, on another ship. Analysis of ship medical logs with regard to patient complaint, diagnosis, and treatment. Of 1,547 new patient visits, 12% were related to injuries and 88% to medical problems; 97% of visits were noncritical, and 3% required immediate emergency intervention. Among these were four cardiac arrests, two stab wounds, two serious ocular injuries, one closed-head injury, and one near-drowning. Five patients required endotracheal intubation. There is a sizeable number of visits to ships' hospitals by patients with acute and serious problems of a wide variety. Physicians and nurses with significant emergency training or experience are best qualified to deal with this broad spectrum of patient problems in this isolated environment.


Simpson's paradox and clinical trials: what you find is not necessarily what you prove.

Expensive clinical trials have become the gold standard for evaluating the efficacy of promising new therapeutic agents. Full exploration of the collected data is routine to maximize the yield of the information available. However, potential methodologic flaws in these extensive analyses may not be appreciated by investigators or readers. One such problem with subgroup analyses is discussed, using hypothetical examples and data from a recently completed clinical trial of brain resuscitation as illustrations.


Adenosine in the treatment of paroxysmal supraventricular tachycardia in children.

Intravenous bolus adenosine was given to four pediatric patients aged 1 month to 8 years who had paroxysmal supraventricular tachycardia that had not responded to conventional medical therapy. Adenosine (one to three doses) was successful in converting the arrhythmia to normal sinus rhythm in all four cases, and no side effects of the drug were noted.


Bilateral cortical blindness: an unusual presentation of bacterial endocarditis.

We report the case of a 37-year-old woman who presented to the emergency department with the initial complaint of complete blindness. The patient was found to have bilateral ruptured occipital mycotic aneurysms as a sequela of bacterial endocarditis. This case is unique in several aspects. Although blindness may be a presenting neurologic symptom, it is exceedingly rare. To our knowledge, bilateral cortical blindness secondary to mycotic aneurysm rupture has not been reported previously.


Spontaneous renal artery thrombosis associated with altered mental status.

Renal artery thrombosis is much less common than renal artery occlusion by emboli. When it does occur, it is usually a result of blunt abdominal trauma or a thrombus superimposed on an atherosclerotic plaque. Numerous other factors have been associated with renal artery thrombosis. Spontaneous renal artery thrombosis is a rare phenomenon in itself. This case represents spontaneous renal artery thrombosis associated with an altered mental status. Clinical features with suspected etiologies are reviewed. Recommendations for future evaluations are given.


Aortic saddle embolus presenting with transient lower extremity paresthesia.

We report the case of a 58-year-old woman who developed acute onset of bilateral lower-extremity numbness and difficulty ambulating at home. On presentation to the emergency department, however, the patient's symptoms essentially had resolved. An aortic saddle embolus was suspected based on the patient's cardiac history and the absence of distal pulses in the lower extremities. This case illustrates that even with vague or resolving complaints, a high index of suspicion should be maintained for the diagnosis of aortic saddle embolus based on the patient's medical history and on physical examination.


Clinically occult presentation of comminuted intertrochanteric hip fractures.

Hip fractures in awake patients are rarely subtle in their clinical presentation. We report two cases of occult, comminuted, intertrochanteric hip fractures that occurred in awake, elderly patients who were brought to the emergency department for evaluation of other medical conditions. Neither patient complained of hip pain, and both were transported to the ED without spinal immobilization. Physical examination revealed no sign of hip fracture. Patient 1 was scheduled for admission and just prior to transfer out of the ED developed hip pain. Patient 2 was admitted for workup of possible transient ischemic attack and approximately 2.5 hours after admission complained of hip pain. Radiographs of both patients revealed comminuted intertrochanteric hip fractures. In an elderly, nonambulatory patient who may have fallen prior to evaluation, routine radiographs of the pelvis and hip should be performed followed by plain tomography, computed tomography, bone scan, or magnetic resonance imaging as indicated to rule out occult hip fracture. Even comminuted intertrochanteric hip fractures can present in an occult fashion; therefore, a high index of suspicion must be maintained for these injuries.


Psychological factors in abortion. A review.

Psychological research is increasingly involved in debates regarding abortion. While recognizing the diversity of ethical and moral issues intertwined with abortion, the American Psychological Association (APA) has focused its involvement on psychological factors, most recently by appointing an expert panel to review the literature on psychological effects. This article notes the history of APA involvement and reports on the panel's conclusions. It presents evidence that abortion is not likely to be followed by severe psychological responses and that psychological aspects can best be understood within a framework of normal stress and coping rather than a model of psychopathology. Correlates of more negative responses following abortion are also discussed.


Broken hearts or broken bonds. Love and death in historical perspective.

Psychological theories and practices frequently neglect the extent to which their subject matter is historically and culturally defined. This issue is explored in the context of theories and therapies related to bereavement. Contemporary orientations emphasize the importance of breaking bonds with the deceased and the return of survivors to autonomous lifestyles. Placing the orientation in cultural and historical context reveals that it is largely a product of a modernist worldview. Within the romanticist ethos of the preceding century, such breaking of bonds would destroy one's identity and the meaning of life. In light of contemporary variations in subcultural meanings and values, a postmodern view is suggested in which reflexive responsibility is focal.


Effect of tidal volume on gas exchange and oxygen transport in the adult respiratory distress syndrome.

The effect of tidal volume (VT) on gas exchange and oxygen delivery (DO2) was studied in nine patients with adult respiratory distress syndrome (ARDS) and in 10 postoperative open-heart surgery patients (CABG). During controlled mechanical ventilation, VT was initially 10 to 12 ml/kg, followed by an increase and reduction of 25% (1.25 VT and 0.75 VT, respectively). In both groups of patients, dead space (VD) correlated strongly with VT (p < 0.001), while the VD/VT ratio was independent of VT. PaO2 tended to increase in CABG patients and decrease in ARDS patients at 1.25 VT. Arterial oxygen saturation (SaO2) did not change at 1.25 VT but decreased at 0.75 VT (p < 0.001) in the ARDS group. Venous admixture (QS/QT) decreased with 1.25 VT and increased with 0.75 VT (p < 0.001). A relatively larger increase in cardiac output compensated for the increased QS/QT and the reduced SaO2, resulting in significantly higher DO2 with 0.75 VT (p < 0.01). A lower VT resulted in improved balance between pulmonary gas exchange and whole body oxygen supply.


Use of a measurement of pulmonary hyperinflation to control the level of mechanical ventilation in patients with acute severe asthma.

Mechanical ventilation causes significant morbidity and mortality in patients with severe asthma. Hypoventilation may reduce this morbidity and mortality, but indicators to guide the degree of hypoventilation are unclear. We used a measure of pulmonary hyperinflation to assess the degree of airflow obstruction and to guide the extent and duration of hypoventilation. Ten patients who required mechanical ventilation for acute severe asthma were studied. All were sedated, paralyzed, and given an initial minute ventilation (VE) of 200 ml/kg/min. End-inspiratory lung volume (VEI) above FRC was measured from the total exhaled gas volume during 40 to 60 s of apnea. VEI was used to regulate VE to a safe level (VEsafe), irrespective of PaCO2, by reducing the rate when VEI was > 20 ml/kg and increasing it when VEI was < 20 ml/kg. Each patient was weaned when VEsafe resulted in PaCO2 < or = 40 mm Hg (the weaning point). FRC was measured computer analysis of anterior and lateral chest radiographs taken at the end of apnea. Using the weaning point criterion, 2 patients (PaCO2 < 40 mm Hg) were weaned shortly after arrival. The remaining eight (initial PaCO2, 63 +/- 17 mm Hg) continued hypoventilation until the weaning point was reached (30 +/- 29 h). The weaning point was reached by the VE required for PaCO2 40 mm Hg decreasing concurrent with the VEsafe increasing. All but 1 patient were successfully weaned within 24 h of the weaning point.(ABSTRACT TRUNCATED AT 250 WORDS)