Haemodilutional effect of standard fluid management limits the effectiveness of acute normovolaemic haemodilution in AAA surgery--results of a pilot trial. Hemodynamic effects of hypertonic hydroxyethyl starch 6% solution and isotonic hydroxyethyl starch 6% solution after declamping during abdominal aortic aneurysm repair. Comparison of hemodynamic, pulmonary, and renal effects of use of three types of fluids after major surgical procedures on the abdominal aorta. The preservation of renal function by isovolemic hemodilution during aortic operations. Randomized controlled trial of the effect of mannitol on renal reperfusion injury during aortic aneurysm surgery. Gastric intramucosal pH changes after volume replacement with hydroxyethyl starch or crystalloid in patients undergoing elective abdominal aortic aneurysm repair. The reduction of the allogenic transfusion requirement in aortic surgery with a hemoglobin-based solution. Hypertonic sodium lactate versus lactated ringer's solution for intravenous fluid therapy in operations on the abdominal aorta. Randomized study comparing the effects of hydroxyethyl starch solution with Gelofusine on pulmonary function in patients undergoing abdominal aortic aneurysm surgery. Crystalloid vs. colloid resuscitation: is one better? A randomized clinical study. [Effect of infusion of hypertonic-hyperoncotic solution on cardiovascular function in surgery of the abdominal aorta during the perioperative period]. Cardiac response is greater for colloid than saline fluid loading after cardiac or vascular surgery. Safety of HES 130/0.4 (Voluven(R)) in patients with preoperative renal dysfunction undergoing abdominal aortic surgery: a prospective, randomized, controlled, parallel-group multicentre trial. Effect of preoperative normovolemic hemodilution on left ventricular segmental wall motion during abdominal aortic surgery. Hemodynamic and cardiometabolic effects of infrarenal aortic and common iliac artery declamping in man--an approach to optimal volume loading. Extracellular fluid and colloid osmotic pressure in abdominal vascular surgery. A study of volume changes. Effects of a hemoglobin-based oxygen carrier (HBOC-201) on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. Effect of hypertonic saline dextran on acid-base balance in patients undergoing surgery of abdominal aortic aneurysm. Haemodynamic effects of diaspirin crosslinked haemoglobin (DCLHb) given before abdominal aortic aneurysm surgery. Haemodynamics and 'optimal' hydration in aortic cross clamping. Effect of bicarbonated Ringer's solution on the acid-base balance in patients undergoing abdominal aortic aneurysm repair. [Use of a hypertonic solution of 7.5% NaCl in preventing post-declamping hypotension of the abdominal aorta]. Splanchnic oxygenation in patients undergoing abdominal aortic aneurysm repair and volume expansion with eloHAES. [Comparative study of the intraoperative effectiveness of 5% human albumin or 10% hydroxyethyl starch (HAES-steril) on hemodynamics and oxygen transport in 40 patients]. Normal saline versus lactated Ringer's solution for intraoperative fluid management in patients undergoing abdominal aortic aneurysm repair: an outcome study. Optimal fluid management after aortic reconstruction: a prospective study of two crystalloid solutions. A prospective trial of diaspirin cross-linked hemoglobin solution in patients after elective repair of abdominal aortic aneurysm. Comparison of hetastarch to albumin for perioperative bleeding in patients undergoing abdominal aortic aneurysm surgery. A prospective, randomized study. Intraoperative glucose infusion and blood lactate: endocrine and metabolic relationships during abdominal aortic surgery. Gastric intramucosal pH-guided therapy in patients after elective repair of infrarenal abdominal aneurysms: is it beneficial? The effects of increased doses of bovine hemoglobin on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. Randomized trial of albumin vs. electrolyte solutions during abdominal aortic operations. Randomized clinical trial comparing the effects on renal function of hydroxyethyl starch or gelatine during aortic aneurysm surgery. Low molecular weight hydroxyethyl starch 6% compared to albumin 4% during intentional hemodilution.
To evaluate the impact of standard fluid management on the effectiveness of ANH as a blood conservation method in elective open AAA repair.
                Prospective randomised controlled study.
                Thirty-four patients undergoing elective AAA repair were randomised to have ANH (16) or act as controls (18). Intra-operative cell salvage was permitted in both groups. Haemoglobin (Hb) concentrations were determined at variable intervals peri-operatively. Blood loss and the use of heterologous blood were recorded.
                The pre- and post-operative Hb concentrations, surgical blood loss and the use of cell salvage were similar in both groups. Hb concentration (median, range) decreased significantly from pre-operative to aortic clamping (with blood loss <100 ml) in ANH patients from 8.8 (7.5-10.2) to 5.7 (4.2-6.6)mmol/l following ANH but also in controls from 8.6 (7.5-9.7) to 7.0 (4.5-9.0)mmol/l due to fluid infusion (P<0.01 for every comparison). Bank blood requirements were similar: median 2 units in ANH and 2.5 units in control patients (P=0.68).
                Large volumes of fluids infused during AAA repair already conserve blood by the mechanism of hypervolaemic haemodilution. When cell salvage is used with standard fluid management during AAA repair, additional ANH is ineffective in saving blood. Fluid resuscitation with hypertonic hydroxyethyl starch solutions (HES) is effective in haemorrhagic shock due to the rapid mobilisation of fluids into the intravascular compartment. Declamping of the abdominal aorta with acute redistribution of blood into the vessels of the lower body half causes declamping-induced hypotension. Usually large amount of fluids or vasopressors are necessary to restore hemodynamic stability. Therefore, infusion of a hypertonic colloid solution may be an attractive option to achieve hemodynamic stability. This study was conducted to determine the amount of fluid of either hypertonic HES (HES 6%;7.2% NaCl) or isotonic HES (HES 6%;0.9% NaCl) needed to attain best wedge pressure (PCWP) cardiac index (CI) relation after declamping. Thirty-two high-risk patients undergoing elective abdominal aneurysm resection were enrolled in a prospective, randomised, double blinded study. The individual optimised PCWP/CI relation was determined after induction of anaesthesia. After declamping, both solutions were titrated in small boluses of 100 mL until the previously determined best wedge was reached. The amount of fluid after declamping was significantly reduced in the hypertonic HES- group 162 mL vs. 265 mL in the control group (P < 0.05). Resuscitation time was shortened, and cardiac index was slightly higher in the treatment group. The use of hypertonic HES-solution after aortic declamping led to a significant reduction of fluids necessary to attain optimised PCWP/CI relation. In this clinical trial with moderate blood loss in high-risk patients, hypertonic HES applied in a titrated fashion restored hemodynamic stability faster and without volume overload. Hemodynamic, pulmonary, and renal variables were measured in 24 patients scheduled for major abdominal aortic operations. Control values were obtained before preoperative medications were given. All patients received 5% dextrose in Lactated Ringer's solution intraoperatively. Postoperatively, group 1 patients received 5% dextrose in water plus albumin, group 2 received 5% dextrose in 0.45 sodium chloride solution, and group 3 received 5% dextrose in lactated Ringer's solution. There were significant increases in Qs/Qt and AaDO2, 48 hours after operation in group 3. Oxygen consumption and cardiac output increased in all groups 24 hours after operation. Twenty-four hours later, these two variables returned to control values in group 1 but continued to rise in the other two groups. Significant diuresis occurred in group 1, 48 hours postoperatively, whereas the other two groups continued to retain water. Use of albumin and 5% dextrose in water in the postoperative period seemed to produce less deviations from control values of most measured variables, than the other two groups. In an investigation of the effects of isovolemic hemodilution, 39 consecutive patients undergoing elective infrarenal aortic operation had detailed measurements of renal function, renal artery blood flow, and cardiac hemodynamics.
                The patients were randomly allocated to receive acute preoperative isovolemic hemodilution to a hematocrit of 28%, with 20 patients receiving hemodilution and 19 being control subjects.
                Twelve (63%) of the control group had renal impairment, compared with only four (20% in the group receiving hemodilution (p < 0.01). Hemodilution also prevented the fall in cardiac output induced by cross-clamping (p < 0.01) and significantly reduced the need for transfusion of donor blood (p < 0.01).
                Acute isovolemic hemodilution is clearly a useful adjunct in the management of patients undergoing elective aortic operation. The effects of mannitol on renal impairment following infrarenal aortic aneurysm repair were studied. Patients received either mannitol 0.3 g/kg (n = 15) or saline (n = 13) as a rapid intravenous infusion before aortic cross-clamping. One patient in the control group developed fatal postoperative renal failure but there was no renal failure in the mannitol group. Two patients treated with mannitol died from perioperative myocardial infarction. There were no significant differences in postoperative blood urea level, serum creatinine concentration or creatinine clearance between mannitol and control groups. In patients who had mannitol there was a significant diuresis on the first day after operation (mean urine output 2250 ml) compared with before operation (1557 ml) (P = 0.007). Compared with controls, patients treated with mannitol had lower mean (s.e.m.) postoperative levels of urinary albumin (160(32) versus 500(140) mg per mmol creatinine; P = 0.036) and N-acetyl glucosaminidase (143(34) versus 271(70) mumol per mmol creatinine; P = 0.04) indicating a reduced level of subclinical glomerular and renal tubular damage. These data demonstrate that mannitol reduces subclinical renal injury following infrarenal aortic aneurysm repair. Gastric intramucosal pH (pHi), a surrogate marker of tissue oxygenation, falls following abdominal aorta aneurysm (AAA) repair. We tested the hypothesis that volume replacement with a hydroxyethyl starch solution would result in better preserved splanchnic oxygenation than would volume replacement with crystalloid solutions.
                This was a prospective, randomized, nonblinded study set in a university-affiliated community hospital. Thirty patients undergoing elective AAA repair were studied. Patients were randomly selected to receive intraoperative and postoperative fluid replacement with either hetastarch or crystalloid. According to the study protocol, patients could not receive in excess of 3,000 mL of hetastarch. Tissue oxygenation was assessed indirectly by measuring pHi using a nasogastric tonometer. Hemodynamic, oxygenation, and pHi data were collected preoperatively, preclamp, before unclamping, at the end of the procedure and postoperatively for 24 hours. Coagulation parameters were determined preoperatively and postoperatively for 24 hours.
                Fifteen patients were randomized to each group. There were 18 male and 12 female patients, whose mean age was 66 +/- 9 years. The intraoperative fluid balance was significantly greater in the crystalloid compared with the hetastarch group (4,194 +/- 1,500 mL v 2,949 +/- 1,123 mL; P = .05, 95% confidence interval [C] 23 to 2,519 mL). There were no significant differences in the amount of intraoperative blood loss or postoperative transfusion requirements between the two groups. The difference between the preoperative pHi and nadir was 0.07 +/- 0.03 in the hetastarch group compared with 0.13 +/- 0.04 in the crystalloid group (P = .001, Cl 0.03 to 0.09). By multivariate analysis the only variable that influenced the fall in pHi was the type of resuscitation fluid (F ratio of 7.63; P = .01). There were no significant differences in hemodynamic- and oxygenation-derived variables or coagulation parameters between the two groups of patients. The length of mechanical ventilation, intensive care unit, and hospital stay was comparable between the two groups of patients.
                In patients undergoing major surgery, volume resuscitation with hydroxyethyl starch solutions may improve microvascular blood flow and tissue oxygenation. Because of allogenic red blood cell (RBC) availability and infection problems, novel alternatives, including hemoglobin-based oxygen-carrying solutions (HBOC), are being explored to minimize the perioperative requirement of RBC transfusions. This study evaluated HBOC-201, a room-temperature stable, polymerized, bovine-HBOC, as a substitute for allogenic RBC transfusion in patients undergoing elective infrarenal aortic operations.
                In a single blind, multicenter trial, 72 patients were prospectively randomized two-to-one to HBOC (n = 48) or allogenic RBC (n = 24) at the time of the first transfusion decision, either during or after elective infrarenal aortic reconstruction. Patients randomized to the HBOC group received 60 g of HBOC for the initial transfusion and had the option to receive three more doses (30 g each) within 96 hours. In this group, any further blood requirement was met with allogenic RBCs. Patients randomized to the allogenic RBC group received only standard RBC transfusions. The efficacy analysis was a means of assessing the ability of HBOC to eliminate the requirement for any allogenic RBC transfusions from the time of randomization through 28 days. Safety was evaluated by means of standard clinical trial methods.
                The two treatment groups were comparable for all baseline characteristics. Although all patients in the allogenic RBC group required at least one allogenic RBC transfusion, 13 of 48 patients (27%; 95% CI, 15% to 42%) in the HBOC group did not require any allogenic RBC transfusions. The only significant changes documented were a 15% increase in mean arterial pressure and a three-fold peak increase in serum urea nitrogen concentration after HBOC. The complications were similar in both groups, with no allergic reactions. There were two perioperative deaths (8%) in the allogenic RBC group and three perioperative deaths (6%) in the HBOC group (P = 1.0).
                HBOC significantly eliminated the need for any allogenic RBC transfusion in 27% of patients undergoing infrarenal aortic reconstruction, but did not reduce the median allogenic RBC requirement. HBOC transfusion was well tolerated and did not influence morbidity or mortality rates. Fifty-eight patients who were to undergo aortic reconstruction were prospectively randomized into two groups to compare the effects of perioperative fluid replacement with isotonic and hypertonic crystalloid solutions. Blood loss was replaced with packed red blood cells, and additional fluid was given as either Ringer's lactate solution (RL, 130 mEq sodium/L, 274 mOsm/L) or a hypertonic balanced salt solution (HSL, 250 mEq sodium/L, 514 mOsm/L). Fluid was administered to maintain the cardiac filling pressure within 3 torr of the preoperative level and the cardiac output (CO) at or above the preoperative level. The groups were similar with respect to age, preexisting disease, duration of operation, and operative blood loss. During the operation, the RL group required 9.5 +/- 0.8 L of fluid, whereas the HSL group required 4.5 +/- 0.3 L (P less than 0.001). Pulmonary, cardiac, and renal functions were adequately maintained in both groups. There were no significant differences between the groups with regard to CO, urine output, or creatinine clearance during the operation and early postoperative period. Postoperatively, the intrapulmonary shunt was 20 +/- 1% in the RL group and it was 16 +/- 1% in the HSL group (P less than 0.05). The amount of sodium infused and the cumulative sodium balance at the completion of the study period were similar in both groups. Serum sodium and osmolarity were significantly greater in the HSL group (P less than 0.001), reaching a maximum of 151 +/- 1 mEq/L and 305 +/- 2 mOsm/L, respectively. Two patients in the HSL group had a persistent elevation in serum osmolarity (greater than 320 mOsm/L) during operation, for which they received RL for the balance of the resuscitation. There were no complications that could be attributed to the hypertonicity of the solution. HSL is effective for resuscitation of patients with extracellular fluid deficit and is safe provided that the serum sodium and osmolarity are monitored during periods of large volume administration. Restoring blood flow to ischaemic tissue can cause lung damage with pulmonary oedema. Hydroxyethyl starch (HES) solution, when used for volume replacement, may modify and reduce the degree of ischaemia-reperfusion injury. We compared the effects of HES solution with those of Gelofusine solution on pulmonary function, microvascular permeability and neutrophil activation in patients undergoing elective infrarenal abdominal aortic aneurysm surgery.
                Forty patients were randomized into two groups. The anaesthetic technique was standardized. Lung function was assessed with the PO(2)/FI(O(2)) ratio, respiratory compliance, chest x-ray and a score for lung injury. Microvascular permeability was determined by measuring microalbuminuria. Neutrophil activation was determined by measurement of plasma elastase.
                Four hours after surgery, the median (quartile values) PO(2)/FI(O(2)) ratio was 40.3 (37.8, 53.1) kPa for the HES-treated patients compared with 33.9 (31.2, 40.9) kPa for the Gelofusine-treated patients (P<0.01, Mann-Whitney test). The respiratory compliance was 80 (73.5, 80) ml cm(-1) H(2)O in the HES-treated patients compared with 60.1 (50.8, 73.3) ml cm(-1) H(2)O in the Gelofusine-treated patients (P<0.01, Mann-Whitney test). The lung injury score 4 h after surgery was less for the patients treated with HES compared with the patients treated with Gelofusine (0.33 vs 0.71, P=0.01, Wilcoxon rank sum test). Mean (SD) plasma elastase was less in the HES-treated patients on the first postoperative day (1.96 (0.17) vs 2.08 (0.24), P<0.05). The log mean microalbuminuria was less in the HES-treated patients (0.41 vs 0.91 mg mmol(-1), P<0.05). This difference in microvascular permeability was associated with different volumes of colloid required to maintain stable cardiovascular measurements in the two groups of patients studied (3000 vs 3500 ml, P<0.01, Mann-Whitney test).
                Compared with Gelofusine, the perioperative pulmonary function of patients treated with HES after abdominal aortic aneurysm surgery was better. The effects of hemodynamic resuscitation with protein-containing or balanced salt solution were studied prospectively in 29 patients undergoing abdominal aortic surgery. Blood loss was replaced with packed red cells and extracellular volume with either Ringer's Lactate (RL) or 5% albumin in Ringer's lactate (ALB). Fluids were given to maintain the pulmonary capillary wedge pressure (PCWP) equal to or within 5 torr above preoperative (PO) levels, the cardiac output (CO) equal to or greater than preoperative values, and the urine output at least 50 ml/hr. Serum colloid osmotic pressure (COP), CO, PCWP, the gradient between COP and PCWP (COP-PCWP), and intrapulmonary shunt (Qs/Qt) were measured PO, intraoperatively (IO), and daily for 3 days. The measured variables were similar PO in both groups. Operation time, estimated blood loss, and transfusions were similar. Total fluids received for resuscitation (day of operation) was 11.3 +/- 0.8 liters (RL) and 6.2 +/- 0.4 liters (ALB). Fluid balance at the end of resuscitation was 8.4 +/- 0.8 liters (RL) and 3.4 +/- 0.5 liters (ALB). Maximum decrease in COP was 40% (P less than 0.001) in the RL group and was insignificant in the ALB group. The COP-PCWP decreased from 11 +/- 1 to 2 +/- 1 in RL (P less than 0.001) and insignificantly in ALB. Qs/Qt increased slightly in both groups following operation but was not different between groups. Fluid balance, total fluid infused, sodium balance, total sodium infused, COP, or COP-PCWP did not significantly correlate with Qs/Qt. Two patients in the ALB group experienced pulmonary edema associated with normal COPs and elevated PCWPs. There were no cases of pulmonary edema associated with low COPs and normal PCWPs in the crystalloid group. These data seriously question the necessity to maintain COP by using protein-containing solutions during acute hemodynamic resuscitation. When titrated to physiological end points, even large volumes of balanced salt solutions are tolerated well. When blood flow is decreased, as in prolonged hypovolaemia and hypotension, or in the course of transversal clamping of the aorta during aortic reconstruction, nutritive tissue perfusion can also fall below the critical level.
                The objective of this study was to analyse the effects of hypertonic-hyperoncotic solution on cardiovascular function during reconstruction of the abdominal aorta.
                This prospective randomised study included 40 patients. All patients underwent surgery of the abdominal aorta under general endotracheal anaesthesia. Based on the type of solution infused from the time of clamping to the moment of the removal of the transversal aortic clamp, the patients were divided into two groups of 20. The study group was infused with a small volume of hypertonic-hyperoncotic solution, while the controls were administered infusions of isotonic solution. Patients with a preoperative creatinine level over 130 micromol L(-1) and an ejection fraction of less than 40% were excluded from the study.
                Cardiac output increased from 5.67 +/- 2.95 to 7.05 +/- 3.39 L min(-1) in the study group, in comparison to the controls, where it increased from 4.98 +/- 2.06 to 5.99 +/- 3.02 L min(-1) (p = 0.004). Central venous pressure increased from 8.75 +/- 3.67 to 9.30 +/- 2.77 mm Hg in the study group, in comparison to the controls, where the values decreased from 6.84 +/- 2.73 to 6.45 +/- 2.50 mm Hg (p = 0.022). Diastolic pulmonary artery pressure increased from 15.92 +/- 5.61 to 16.65 +/- 6.53 mm Hg in the study group, in comparison to the controls, where it decreased from 12.65 +/- 4.28 to 11.85 +/- 3.91 mm Hg (p = 0.021). The amount of given crystalloids 24 hours after the removal of the aortic clamp totalled 2562.5 +/- 485.82 mL in the study group, versus 3350 +/- 727.29 mL in the control group (p = 0.000). The amount of given human albumins 24 hours after the removal of the aortic clamp totalled 30 +/- 49.74 mL in the study group versus 100 +/- 4.34 mL in the control group (p = 0.001). CONCLUSION Haemodynamic stability of patients and adequate organ perfusion during surgery are achieved through the infusion of hypertonic-hyperoncotic solution, which maintains optimal values of: cardiac output, mixed venous oxygen saturation, and delivery of oxygen, while reducing alveolo-arterial oxygen difference. The balance of fluids, 24 hours after the removal of the aortic clamp, was maintained with the aid of hypertonic-hyperoncotic solution, while isotonic solution produced an excess of over 1000 mL of fluid in the control patients. Hypertonic-hyperoncotic solution increases cardiac output considerably more than does isotonic solution, and its application significantly reduces the accumulation of crystalloid solutions and human albumins. To study the effects on volume expansion and myocardial function of colloids or crystalloids in the treatment of hypovolaemic hypotension after cardiac and major vascular surgery.
                A single-centre, single-blinded, randomized clinical trial at the intensive care unit of a university hospital.
                Patients (n=67) were subjected to a 90-min filling pressure-guided fluid challenge with saline 0.9% or the colloids gelatin 4%, hydroxyethyl starch 6% or albumin 5%. Biochemical variables and haemodynamics (transpulmonary thermodilution) were measured.
                An amount of 1800 (1300-1800) ml of saline or 1600 (750-1800) ml of colloid solution (P< 0.005) was infused. Colloid osmotic pressure (COP) decreased in the saline group and increased in the colloid groups (P< 0.001). Plasma volume increased by 3.0% (-18 to 24) in the saline versus 19% (-11 to 50) in the colloid groups (P< 0.001). Cardiac index increased by median 13% (ns) in the saline group and by 22% in the colloid groups (P<0.005). The rise in left ventricular stroke work index was greater in the colloid than in the saline groups. The different colloids were equally effective. The rise in cardiac index related to the rise in plasma volume and global end-diastolic volume, confirming plasma volume and preload augmentation by the fluid loading.
                After cardiac or major vascular surgery, the pressure- and time-guided fluid response is dependent on the type of fluid used. Colloid fluid loading leads to a greater increase in preload-recruitable cardiac and left ventricular stroke work indices than that with saline, because of greater plasma volume expansion following an increase in plasma COP. Patients with impaired renal function are at risk of developing renal dysfunction after abdominal aortic surgery. This study investigated the safety profile of a recent medium-molecular-weight hydroxyethyl starch (HES) preparation with a low molar substitution (HES 130/0.4) in this sensitive patient group.
                Sixty-five patients were randomly allocated to receive either 6% hydroxyethyl starch (Voluven); n = 32) or 3% gelatin (Plasmion); n = 33) for perioperative volume substitution. At baseline, renal function was impaired in all study patients as indicated by a measured creatinine clearance < 80 mL min(-1). The main renal safety parameter was the peak increase in serum creatinine up to day 6 after surgery.
                Both treatment groups were compared for non-inferiority (pre-defined non-inferiority range hydroxyethyl starch < gelatin + 17.68 micromol L(-1) or 0.2 mg dL(-1). Other renal safety parameters included minimum postoperative creatinine clearance, incidence of oliguria and adverse events of the renal system. Baseline characteristics, surgical procedures and the mean total infusion volume were comparable. Non-inferiority of hydroxyethyl starch vs. gelatin could be shown by means of the appropriate non-parametric one-sided 95% CI for the difference hydroxyethyl starch-gelatin [-infinity, 11 micromol L(-1)]. Oliguria was encountered in three patients of the hydroxyethyl starch and four of the gelatin treatment group. One patient receiving gelatin required dialysis secondary to surgical complications. Two patients of each treatment group died.
                As we found no drug-related adverse effects of hydroxyethyl starch on renal function, we conclude that the choice of the colloid had no impact on renal safety parameters and outcome in patients with decreased renal function undergoing elective abdominal aortic surgery. Preoperative normovolemic hemodilution (PNH) has been proposed for patients scheduled to undergo aortic surgery. Coronary artery disease is frequent in these patients. The aim of the study was to assess the effect of PNH on hemodynamics and segmental wall motion (SWM) evaluated by transesophageal echocardiography in such patients. Twenty patients with coronary artery disease were allocated randomly to either PNH or no PNH; PNH was performed after anesthetic induction using dextran 60,000. Patients were operated on under general anesthesia and monitored intraoperatively with electrocardiographic lead CM5, radial and pulmonary artery catheters, and transesophageal echocardiography positioned to obtain a short-axis view. Hemodynamic and transesophageal echocardiographic data were collected after anesthetic induction and after PNH, before and 5 min after aortic clamping, after unclamping, and at the end of surgery. Aortic clamping induced a significant increase in systemic vascular resistance and arteriovenous difference in oxygen and a decrease in cardiac index (P < 0.05), but the effect of aortic clamping was inversely related to hemodilution. The SWM score (graded from 1 = normal to 5 = dyskinesia) was significantly increased after aortic clamping, mainly in the anterior segment (P < 0.05). Four patients in the control (no PNH) group and one in the PNH group developed new SWM abnormalities indicative of myocardial ischemia during surgery (P = NS). This study suggests that PNH may improve hemodynamic tolerance to aortic clamping in patients with coronary artery disease. The observed changes in SWM indicate that PNH may not worsen myocardial ischemia in patients scheduled to undergo aortic surgery. Nineteen patients undergoing abdominal aortic aneurysm surgery were randomly assigned to two groups and investigated to elucidate the mechanisms of declamping hypotension. The control group of nine patients was kept at an average mean pulmonary artery occlusion pressure (MPAOP) of 11 mmHg (1.46 kPa) before declamping. The other group was volume loaded to a MPAOP of 16 mmHg (2.13 kPa) shortly before declamping. Following declamping there was a significantly greater decrease in mean arterial pressure in the control group, with the same reduction of MPAOP in both groups. In parallel, cardiac and stroke volume indices decreased in the control patients, but remained unchanged in the volume-loaded patients. In the control group there was a reduction in myocardial substrate utilization which was not seen in the volume-loaded patients. No signs of myocardial ischemia could be demonstrated in any of the groups. The results indicate that mismatching between intravascular volume and blood volume is the main cause of infrarenal aortic or common iliac artery declamping hypotension. Volume loading before declamping to a slightly elevated MPAOP can effectively prevent hypotension, while a normal MPAOP does not guarantee a stable hemodynamic situation after declamping. nan We conducted a pilot study to evaluate the effects of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After induction of anesthesia and isovolemic hemodilution with 1 L of lactated Ringer's solution, 13 patients were randomly assigned to receive, within 30 min, 3 mL/kg of either HBOC-201 or 6% hydroxyethyl starch (HES). Monitored variables included invasive arterial and pulmonary artery pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic and pulmonary vascular resistance indices, oxygen delivery index (DO2I), oxygen consumption index (VO2I), and oxygen extraction ratio (O2ER). Thirty minutes after HBOC-201 infusion, mean arterial pressure, systemic vascular resistance index, and CI were 149% (P = 0.028), 169% (P = 0.046), and 75% (P = 0.46) of the preinfusion values, respectively. No significant changes were noticed in heart rate and pulmonary vascular resistance index. DO2I and VO2I, 30 min after the infusion of HBOC-201, were 79% (P = 0.046) and 76% (P = 0.028) of the preinfusion values, respectively, whereas CaO2 and O2ER remained unaffected. We conclude that HBOC-201, at a dose of 3 mL/kg, impairs oxygen delivery because of adverse effects on cardiac output. To evaluate the magnitude and cause of metabolic acidosis after infusion of 7.5% sodium chloride 6% dextran 70.
                Randomized, prospective clinical study.
                University hospital.
                Two groups of 14 patients each, undergoing repair of abdominal aortic aneurysm.
                Patients were randomly assigned to receive either 250 mL of hypertonic saline dextran (HSD) or a conventional fluid regimen with 250 mL of hydroxyethyl starch in normal saline solution (H-NS) during the period of aortic clamping. Additionally, normal saline was used in both groups to reach a target pulmonary artery occlusion pressure of 15-18 mmHg. pH, Paco2, and serum concentrations of sodium, potassium, magnesium, calcium, chloride, lactate, albumin, and phosphate were measured. Strong ion difference was calculated as (sodium + potassium + magnesium + calcium) - (chloride + lactate). The amount of weak plasma acid was calculated.
                The infusion of HSD resulted in an immediate large increase in serum sodium (19 mmol/L) and chloride (22 mmol/L), whereas the infusion of H-NS led only to mild increases in serum sodium (3 mmol/L) and chloride (6 mmol/L). Both HSD and H-NS caused concomitant and equal decreases in the amount of weak plasma acid, strong ion difference, and pH (7.28-7.30). The reduction of bicarbonate was also identical and proportional to the extent of dilution due to infusion of HSD and H-NS. This induced metabolic acidosis was corrected spontaneously in both groups 24 hrs after surgery.
                Both the intravenous administration of 7.5% sodium chloride and the conventional fluid regimen with saline-based 6% hydroxyethyl starch solution resulted in a metabolic acidosis of equal extent. This suggests dilution of plasma buffers or a decrease in strong ion difference to be the primary cause of metabolic acidosis. We studied 34 patients undergoing elective repair of an abdominal aortic aneurysm under combined general anaesthesia and epidural block to evaluate the acute effects of diaspirin crosslinked haemoglobin (DCLHb) 50, 100 and 200 mg kg-1 i.v. Haemodynamic variables were measured continuously using pulmonary and radial artery catheters, and oxygen delivery and consumption were calculated at regular intervals. DCLHb was shown to be vasoactive, producing an increase in mean arterial pressure of approximately 25% with each dose, with small decreases in cardiac index and calculated oxygen delivery. These effects persisted beyond the end of infusion and provided a degree of cardiovascular stability during the operative procedure. The effects of DCLHb on oxygen consumption at these doses were minimal. The effect of optimal hydration on haemodynamics and renal function during infrarenal aortic cross clamping was studied in 26 consecutive patients operated on because of an infrarenal aortic aneurysm. The patients were randomly divided over two groups. The patients of group B (n = 13) were optimally hydrated before the operation. The Starling curve was used as standard. Patients of group A (n = 13) served as control. The pre-operative and postoperative renal functions of both groups were compared, as were the haemodynamic parameters. The haemodynamic parameters were measured at five minutes intervals during the entire procedure. During aortic clamping the heart rate was significantly lower in patients of group B, indicating a lower myocardial oxygen consumption. Neither the haemodynamic parameters nor the renal function showed other beneficial effects on optimal hydration. The present study was designed to assess whether prophylactic use of bicarbonated Ringer's solution ameliorates metabolic acidosis in patients undergoing aortic surgery.
                Twenty patients undergoing elective infrarenal aortic aneurysm repair were randomly assigned to receive either bicarbonated Ringer's solution or acetated Ringer's solution. The pH, PaCO(2), and base excess (BE) were measured before surgical incision (T0), 5 min before reperfusion (T1), 5 min after reperfusion (T2), and 30 min after reperfusion (T3). Data were compared between the two groups.
                Both pH and BE initially showed a slight decrease in both groups during clamping. After unclamping of the aorta, an additional decrease in pH was observed in both groups (T0 to T2, and T3). There were no significant differences in pH between the groups throughout the study period.
                Aortic cross-clamping leads to the development of metabolic acidosis, with a decrease in pH and BE. The effect of administration of bicarbonated infusion fluid during elective abdominal aortic surgery had not significant compared with that of acetated Ringer's solution with respect to acid-base homeostasis. nan Gastric intramucosal pH (pHi), a surrogate marker of splanchnic oxygenation, falls following abdominal aortic aneurysm surgery.
                To investigate the effects of volume expansion with hydroxyethyl starch (eloHAES) on splanchnic perfusion compared to another colloid such as gelofusine.
                Twenty-two consecutive patients undergoing AAA repair were randomised to receive either eloHAES or gelofusine as plasma expanders. Tissue oxygenation was monitored (10 gelofusine and 12 eloHAES) indirectly by measuring pHi using a nasogastric tonometer.
                Compared to the eloHAES group, the fall in pHi was significantly greater in the gelofusine group at clamp release (7.29 vs 7.33, P=0.003) and at 4 h following clamp release (7.29 vs 7.33, P=0.03). There was a good inverse correlation between the lowest pHi and the peak serum interleukin-6 (r(s)= -0.47, P=0.03). By multivariate analysis, the only factor that influenced the pHi was the type of colloid used (F=5.54, P=0.005). The eloHAES treated patients required significantly less colloid on the first postoperative day (3175 +/- 175 vs 4065 +/- 269 ml, P=0.01).
                In patients undergoing abdominal aortic aneurysm repair, plasma expansion with eloHAES improves microvascular perfusion and splanchnic oxygenation. In 40 patients, whose expected hemodynamic instability during surgery necessitated invasive monitoring (Swan-Ganz catheter) and arterial pressure monitoring the hemodynamic and oxygen transport parameters in conditions of hypervolemic hemodilution were investigated in randomized tests. After insertion of an arterial catheter (arteria radialis) as well as Swan-Ganz pulmonary arterial catheter via the vena jugularis interna, one of the two volume substitutes selected at random was infused in quantities of 125 ml/5 min and the hemodynamic changes were measured after infusion of 500 ml and finally after a wedge pressure of 18 mmHg was reached. Using either solution, the measurements indicated significant increases in mean arterial pressure as well as in central venous pressure (ZVD) and wedge pressure. The cardiac index, left ventricular stroke work index, and stroke output rose consecutively and pulmonary vascular resistance went down in both test groups. In the case of both volume substitutes, there was an improvement in oxygen availability. The hemoglobin content decreased in both groups, though to different degrees in each group. Although the hydroxyethyl starch group registered a greater improvement in the cardiac index, a bigger decrease in pulmonary vascular resistance, a higher rise in the left ventricular stroke work index and a more significant improvement in stroke output, smaller quantities of the volume substitute were required in this group than in the group in which volume substitution was carried out with human albumin 5%.(ABSTRACT TRUNCATED AT 250 WORDS) Metabolic acidosis and changes in serum osmolarity are consequences of 0.9% normal saline (NS) solution administration. We sought to determine if these physiologic changes influence patient outcome. Patients undergoing aortic reconstructive surgery were enrolled and were randomly assigned to receive lactated Ringer's (LR) solution (n = 33) or NS (n = 33) in a double-blinded fashion. Anesthetic and fluid management were standardized. Multiple measures of outcome were monitored. The NS patients developed a hyperchloremic acidosis and received more bicarbonate therapy (30 +/- 62 mL in the NS group versus 4 +/- 16 mL in the LR group; mean +/- SD), which was given if the base deficit was greater than -5 mEq/L. The NS patients also received a larger volume of platelet transfusion (478 +/- 302 mL in the NS group versus 223 +/- 24 mL in the LR group; mean +/- SD). When all blood products were summed, the NS group received significantly more blood products (P = 0.02). There were no differences in duration of mechanical ventilation, intensive care unit stay, hospital stay, and incidence of complications. When NS was used as the primary intraoperative solution, significantly more acidosis was seen on completion of surgery. This acidosis resulted in no apparent change in outcome but required larger amounts of bicarbonate to achieve predetermined measurements of base deficit and was associated with the use of larger amounts of blood products. These changes should be considered when choosing fluids for surgical procedures involving extensive blood loss and requiring extensive fluid administration.
                Predominant use of 0.9% saline solution in major surgery has little impact on outcome as assessed by duration of mechanical ventilation, intensive care unit stay, hospital stay, and postoperative complications, but it does appear to be associated with increased perioperative blood loss. To determine optimal fluid management after elective aortic surgery we compared postoperative administration of 5% dextrose Ringer's lactate solution (102 patients) with 5% dextrose half-normal saline solution (80 patients). For 72 hours after operation, intravenous fluids were titrated to maintain urine output between 50 and 100 ml/hr. The group receiving 5% dextrose Ringer's lactate required less intravenous volume per day (2005 +/- 138 ml [mean +/- standard error of the mean] vs. 2701 +/- 145 ml, p less than 0.05), gained less weight (0.8 +/- 0.2 kg vs. 3.2 +/- 0.2 kg, p less than 0.05), and sustained less hyponatremia (serum sodium reduction, 0.1 mEq/L vs. 4.5 mEq/L, p less than 0.05). The group receiving 5% dextrose Ringer's lactate exhibited consistently lower pulmonary capillary wedge pressure (7.3 +/- 1.0 mm Hg vs. 11.4 +/- 1.9 mm Hg) and required treatment for fluid overload in 9 of 102 instances compared with 30 of 80 instances with hypotonic saline solution (p less than 0.05). The patients receiving 5% dextrose Ringer's lactate maintained higher arterial PO2 at 40% forced inspiratory oxygen (PaO2, 83 +/- 3 torr vs. PaO2, 67 +/- 5 torr, p less than 0.05). Optimal fluid management was approached by the use of 5% dextrose Ringer's lactate solution postoperatively. The use of hypotonic saline solution after aortic surgery offered no advantage and predisposed the patient to volume overload. We evaluated the safety, pharmacokinetics, and pharmacodynamics of diaspirin cross-linked hemoglobin (DCLHb) solution in patients after repair of abdominal aortic aneurysm. We performed a randomized, single-blind controlled study with 10 patients in the surgical intensive care unit of a tertiary care facility. Within 24 hours after repair of an abdominal aortic aneurysm, each patient received an infusion of DCLHb (50 mg/kg or 35 mL for a 70-kg patient) or an equal volume of hetastarch. Variables were measured before infusion, at 15 and 30 minutes postinfusion, and at hourly intervals up to 72 hours. Compared with controls, the experimental group had significantly greater mean pulmonary artery pressure at 30 minutes (mean +/- SD, 26.4 +/- 3.18 vs. 22.8 +/- 2.86 mm Hg), greater mean arterial pressure through 30 minutes (100.8 +/- 8.67 vs. 81.6 +/- 13.8 mm Hg), and greater plasma hemoglobin through 2 hours (69.3 +/- 6.08 vs. 1.8 +/- 0 g/dL). Cardiac output was significantly less in the DCLHb group at 2 hours (5.34 +/- 7.92 vs. 6.18 +/- 0.54 L/minute), levels of serum bilirubin were significantly less at 24 and 48 hours (94 +/- 0.26 vs. 1.56 +/- 0.73 mg/dL), and platelet counts were significantly greater at 24 hours (128 +/- 35.8 vs. 101 +/- 55.7 mg/dL). The two groups did not differ in oxygen delivery or consumption. One patient treated with DCLHb had a myocardial infarction 36 hours postinfusion. No patient had antibodies to DCLHb. At this dosage, DCLHb was well tolerated without severe organ dysfunction or toxicity. However, its use may lead to decreases in cardiac output because of increases in afterload, which may pose serious problems with left ventricular function. The effects of hetastarch and human albumin solutions on perioperative bleeding and coagulation parameters during abdominal aortic aneurysm repair were compared. In two randomized groups of 20 patients, albumin 5% (group 1) or hetastarch 6% (group 2) 1 g/kg was given during surgery. The remaining perioperative fluids consisted of lactated ringers and packed red blood cells. Perioperative coagulation measurements included partial thromboplastin time, prothrombin time, activated clotting time, platelet count, and bleeding time. Estimated blood loss and the total amount of crystalloid and blood infused were also measured. The surgeon, blind to the colloid used, subjectively rated bleeding on a scale of 1 to 10. There was no significant difference between groups for any measured parameter at any time. Measurements of coagulation function were within normal limits for both groups. Hetastarch does not cause clotting disorders in patients undergoing abdominal aortic aneurysm repair, at least if the quantities used in this study are not exceeded. The hypothesis that increased intraoperative blood lactate depends both on intraoperative glucose supply and inadequate tissue oxygenation occurring during surgery was tested in anesthetized patients undergoing infrarenal abdominal aortic surgery. Twenty surgical patients received either Ringer's solution or 5% glucose solution for intraoperative volume loading. Arterial blood lactate, arterial glucose, hemodynamic variables, insulin, glucagon, cortisol, epinephrine, and norepinephrine were determined preoperatively and intraoperatively. There were no significant changes in hemodynamic values, glucagon, norepinephrine, and epinephrine compared with control values in both groups. Oxygen consumption decreased only during aortic clamping. Cortisol and lactate increased significantly 10 min after aortic clamping until the end in both groups. Glucose 5% solution infusion resulted in significantly greater blood lactate accumulation and significantly greater blood glucose and insulin levels, whereas there were no changes in the patients receiving Ringer's solution. From control until aortic clamping, lactate and glucose were significantly correlated with each other in both groups; after aortic clamping until the end of the procedure, the correlation remained constant in patients in the Ringer's group, whereas no relationship could be demonstrated in those in the glucose group. The authors conclude that intraoperative glucose administration increases intraoperative blood lactate and that blood lactate accumulation depends both on glucose supply and tissue oxygen deficit. Furthermore, none of the hemodynamic metabolic and endocrine factors were reliable for assessing tissue perfusion and metabolic demands during surgery. To determine if gastric intramucosal pH (pHi)-guided therapy reduces the number of complications and length of stay in the intensive care unit (ICU) or the hospital after elective repair of infrarenal abdominal aortic aneurysms.
                Prospective, randomized study.
                Surgical intensive care unit (SICU) of a University Hospital.
                Fifty-five consecutive patients randomized to group 1 (pHi-guided therapy) or to group 2 (control).
                Patients of group 1 with a pHi of lower than 7.32 were treated by means of a prospective protocol in order to increase their pHi to 7.32 or more.
                pHi was determined in both groups on admission to the SICU and thereafter at 6-h intervals. In group 2, the treating physicians were blinded for the pHi values. Complications, APACHE II scores, duration of endotracheal intubation, fluid and vasoactive drug treatment, treatment with vasoactive drugs, length of stay in the SICU and in the hospital and hospital mortality were recorded. There were no differences between groups in terms of the incidence of complications. We found no differences in APACHE II scores on admission, the duration of intubation, SICU or hospital stay, or hospital mortality. In the two groups the incidence of pHi values lower than 7.32 on admission to the SICU was comparable (41% and 42% in groups 1 and 2, respectively). Patients with pHi lower than 7.32 had more major complications during SICU stay (p < 0.05), and periods more than 10 h of persistently low pHi values (< 7.32) were associated with a higher incidence of SICU complications (p < 0.01).
                Low pHi values (< 7.32) and their persistence are predictors of major complications. Treatment to elevate low pHi values does not improve postoperative outcome. Based on these data, we cannot recommend the routine use of gastric tonometers for pHi-guided therapy in these patients. Further studies are warranted to determine adequate treatment of low pHi values that results in beneficial effects on the patient's postoperative course and outcome. In two consecutive studies (Study A and Study B), we evaluated the effects of increasing doses of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After the induction of anesthesia and the exchange of 1 L of blood for 1 L of lactated Ringer's solution, 24 patients (12 in each study) were randomly assigned to receive, within 30 min, a predetermined volume of either HBOC-201 or 6% hydroxyethyl starch (Study A 6.9 mL/kg; Study B 9.2 mL/kg). Monitored variables included systemic and pulmonary arterial pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic (SVRI) and pulmonary (PVRI) vascular resistance indices, oxygen delivery index (DO2I), oxygen consumption index (VO2I), and oxygen extraction ratio (O2ER). In both studies, the infusion of HBOC-201 was associated with increases in SVRI (Study A 121%; Study B 71%) and PVRI (Study A 70%; Study B 53%) and with a decrease in CI (29% both studies). Hemodilution with HBOC-201 maintained the arterial oxygen content at levels higher than hemodilution with hydroxyethyl starch, but the advantage of a greater oxygen-carrying capacity was offset by the increase in SVRI, with a resulting net decrease in both CI and DO2I (Study A 30%; Study B 28%); VO2I was maintained by increased O2ER. In terms of hemodynamics and oxygen transport, hemodilution with bovine hemoglobin in these doses provided no apparent benefit over hemodilution with hydroxyethyl starch. Implications: Bovine hemoglobin in doses ranging between 55 and 97 g of hemoglobin increased vascular resistance and decreased cardiac output in anesthetized surgical patients. In terms of hemodynamics and oxygen transport, hemodilution with bovine hemoglobin in these doses provided no apparent benefit over hemodilution with hydroxyethyl starch. In a prospective randomized trial of 16 patients undergoing abdominal vascular reconstructive procedures, changes in plasma volume, serum oncotic pressure (pis), serum albumin and total protein concentration, alveolar to arterial oxygen tension differences (AaDO2, FIO2 = 1.0), creatinine clearance, body weight, and fluid and sodium intake were examined. By random assignment patients received either an albumin- or a sodium-rich intraoperative fluid regimen. Pulmonary arteriovenous admixture was significantly less in the albumin group (n = 7) than in the electrolyte group (n = 9) on the first postoperative day. The change in AaDO2 correlated positively with the total sodium intake in the electrolyte group. Despite the larger fluid load and significantly greater gain of body weight, patients in the electrolyte group had a postoperative plasma volume significantly lower than the preoperative value. Postoperative values of albumin concentration, circulating albumin mass and pis were significantly greater in the albumin group in comparison to the electrolyte group. Creatinine clearance values were not different between the two groups. The change in pis correlated significantly with sodium intake and circulating albumin mass. Pulmonary shunting and expansion of the extracellular fluid volume may be minimized without adverse effects on renal function by administration of fluids rich in albumin in preference to sodium. The optimal colloid for renal protection during abdominal aortic aneurysm (AAA) surgery is not known. This study compared the effects of two hydroxyethyl starch (HES) solutions and gelatine on perioperative renal function.
                Sixty-two patients undergoing AAA surgery were randomized to 6 per cent HES of molecular weight 200/0.62 kDa or 130/0.4 kDa, or 4 per cent gelatine for plasma expansion. Measurements were taken of serum urea and creatinine to mark glomerular filtration, urinary immunoglobulin G : creatinine ratio to mark glomerular membrane function and alpha(1)-microglobulin : creatinine ratio to mark tubular dysfunction before, and for 5 days after, surgery.
                Serum urea was lower in both HES groups than the gelatine group. Serum creatinine was lower with HES 130/0.4 compared with gelatine at days 1, 2 and 5 after surgery (P = 0.020, P = 0.045 and P = 0.045 respectively). Urinary alpha(1)-microglobulin : creatinine ratio was lower with HES 200/0.62 compared with gelatine at 4 and 8 h (P < 0.050) and lower with HES 130/0.4 compared with gelatine at 4 to 24 h, and on days 4 and 5 (P < 0.050). Urinary immunoglobulin G : creatinine was lower in both HES groups compared with gelatine. There was no difference between the two starch groups.
                Compared with gelatine, volume expansion with both types of HES during AAA surgery improved renal function and reduced renal injury. Intentional normovolemic hemodilution was chosen as the model to compare a 6% low molecular weight hydroxyethyl starch (LMW HES) to 4% albumin. The study ran over the plasma exchange period for 24 h. Nine patients, scheduled for abdominal aortic surgery, were included in each group. After basal measurements, blood was withdrawn and simultaneously replaced by either 4% albumin (Group 1) or 6% LMW HES (Group 2) to achieve a final hematocrit of approximately 30%. Hemodynamic blood oxygen gas and hormonal plasma levels were determined before hemodilution then at 30 min, 1, 2, 3, and 24 h after the end of hemodilution. Basal value for total blood volume was 4377 +/- 162 ml in group 1 and 4138 +/- 315 ml in group 2. As in both groups the decrease in blood cell volume was exactly compensated by the increase in plasma volume, no significant change in total blood volume (respectively 4432 +/- 159 and 4305 +/- 267 ml) was observed. Throughout the study, in both groups, no significant change in mean arterial and right atrial pressures was observed. In group 2 (LMW HES), a significant increase of pulmonary capillary wedge pressure was noted 120 min after hemodilution. After hemodilution, despite a significant decrease in arterial oxygen O2 content, systemic oxygen transport did not significantly vary until 24 h in relation to the increased cardiac index. An increase in O2 extraction was observed after the exchange but no further increase was observed until the 24 h. No significant changes either in global O2 consumption or in lactate concentration were detected.(ABSTRACT TRUNCATED AT 250 WORDS)
Despite the confirmed beneficial effects of colloids in this review, further studies are still required. There are no studies examining the effects of combination fluid therapy. The primary research outcome was death, for which results were limited; therefore, future studies should pay more attention to short-term outcomes such as minimising the need for allogenic blood transfusion, complications (organ failure), and length of stay in both the intensive care unit and hospital.