Preliminary Evaluation of a New Index to Predict the Outcome of a Spontaneous Breathing Trial Extubation outcome after spontaneous breathing trials with T-tube or pressure support ventilation. The Spanish Lung Failure Collaborative Group. Predictors and pattern of weaning and long-term outcome of patients with prolonged mechanical ventilation at an acute intensive care unit in North India Diaphragm ultrasound as a predictor of successful extubation from mechanical ventilation Weaning predictors do not predict extubation failure in simple-to-wean patients. The Modified Integrative Weaning Index as a Predictor of Extubation Failure Noninvasive positive-pressure ventilation for respiratory failure after extubation. The tension-time index and the frequency/tidal volume ratio are the major pathophysiologic determinants of weaning failure and success. The oxygen cost of breathing may predict weaning from mechanical ventilation better than the respiratory rate to tidal volume ratio. Reduced breathing variability as a predictor of unsuccessful patient separation from mechanical ventilation* Minute ventilation recovery time: a predictor of extubation outcome. Brain natriuretic peptide as a predictor of weaning from mechanical ventilation in patients with respiratory illness. Automatic tube compensation-assisted respiratory rate to tidal volume ratio improves the prediction of weaning outcome. Myocardial ischemia and weaning failure in patients with coronary artery disease: an update. Effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation. Spanish Lung Failure Collaborative Group. Fluid balance and weaning outcomes Predictors of extubation outcome in patients who have successfully completed a spontaneous breathing trial. Predicting eventual success or failure to wean in patients receiving long-term mechanical ventilation. The unassisted respiratory rate-tidal volume ratio accurately predicts weaning outcome. Protocol-directed weaning from mechanical ventilation: clinical outcome in patients randomized for a 30-min or 120-min trial with pressure support ventilation A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. A pilot study to investigate any relationship between sustained maximal inspiratory pressure and extubation outcome. Effect of failed extubation on the outcome of mechanical ventilation.
BACKGROUND : The available predictors of spontaneous-breathing-trial ( SBT ) success/failure lack accuracy . We devised a new index , the CORE index ( compliance , oxygenation , respiration , and effort ) . OBJECTIVE : To compare the CORE index to the CROP index ( compliance , rate , oxygenation , and pressure ) , airway-occlusion pressure  0.1 s after the start of inspiratory flow ( P0.1 ) , and rapid shallow breathing index ( RSBI ) for predicting SBT success/failure in a critical care environment . METHODS : With 47 mechanically ventilated patients recovering from respiratory failure , of various causes , we prospect ively examined the SBT success/failure prediction accuracy and calculated receiver operating characteristic curves , sensitivity , specificity , and likelihood ratios of CORE , CROP , P0.1 , and RSBI . RESULTS : The specificities were CORE 0.95 , P0.1 0.70 , CROP 0.70 , and RSBI 0.65 . The sensitivities were CORE 1.00 , CROP 1.00 , P0.1 0.93 , and RSBI 0.89 . The areas under the receiver operating characteristic curve were CORE 1.00 ( 95 % CI 0.92–1.00 ) , CROP 0.91 ( 95 % CI 0.79–0.97 ) , P0.1 0.81 ( 95 % CI 0.67–0.91 ) , and RSBI 0.77 ( 95 % CI 0.62–0.88 ) . The positive likelihood ratios were CORE 20.0 , CROP 3.3 , P0.1 3.1 , and RSBI 2.5 . The negative likelihood ratios were CORE 0.0 , CROP 0.0 , P0.1 0.1 , and RSBI 0.2 . CONCLUSIONS : The CORE index was the most accurate predictor of SBT success/failure A 2-h T-tube trial of spontaneous breathing was used in selecting patients ready for extubation and discontinuation of mechanical ventilation . However , some doubt remains as to whether it is the most appropriate method of performing a spontaneous breathing trial . We carried out a prospect i ve , r and omized , multicenter study involving patients who had received mechanical ventilation for more than 48 h and who were considered by their physicians to be ready for weaning according to clinical criteria and st and ard weaning parameters . Patients were r and omly assigned to undergo a 2-h trial of spontaneous breathing in one of two ways : with a T-tube system or with pressure support ventilation of 7 cm H2O . If a patient had signs of poor tolerance at any time during the trial , mechanical ventilation was reinstituted . Patients without these features at the end of the trial were extubated . Of the 246 patients assigned to the T-tube group , 192 successfully completed the trial and were extubated ; 36 of them required reintubation . Of the 238 patients in the group receiving pressure support ventilation  , 205 were extubated and 38 of them required reintubation . The percentage of patients who remained extubated after 48 h was not different between the two groups ( 63 % T-tube , 70 % pressure support ventilation , p = 0.14 ) . The percentage of patients falling the trial was significantly higher when the T-tube was used ( 22 versus 14 % , p = 0.03 ) . Clinical evolution during the trial was not different in patients reintubated and successfully extubated . ICU mortality among reintubated patients was significantly higher than in successfully extubated patients ( 27 versus 2.6 % , p < 0.001 ) . Spontaneous breathing trials with pressure support or T-tube are suitable methods for successful discontinuation of ventilator support in patients without problems to resume spontaneous breathing Objective This study aim ed to examine the clinical characteristics , weaning pattern , and outcome of patients requiring prolonged mechanical ventilation in acute intensive care unit setting s in a re source -limited country . Methods This was a prospect i ve single-center observational study in India , where all adult patients requiring prolonged ventilation  were followed for weaning duration and pattern and for survival at both intensive care unit discharge and at 12 months . The definition of prolonged mechanical ventilation used was that of the National Association for Medical Direction of Respiratory Care . Results During the one-year period , 49 patients with a mean age of 49.7 years had prolonged ventilation ; 63 % were male , and 84 % had a medical illness . The median APACHE II and SOFA scores on admission were 17 and 9 , respectively . The median number of ventilation days was 37 . The most common reason for starting ventilation was respiratory failure secondary to sepsis ( 67 % ) . Weaning was initiated in 39 ( 79.5 % ) patients , with success in 34 ( 87 % ) . The median weaning duration was 14 ( 9.5 - 19 ) days , and the median length of intensive care unit stay was 39 ( 32 - 58.5 ) days . Duration of vasopressor support and need for hemodialysis were significant independent predictors of unsuccessful ventilator liberation . At the 12-month follow-up , 65 % had survived . Conclusion In acute intensive care units , more than one-fourth of patients with invasive ventilation required prolonged ventilation . Successful weaning was achieved in two-thirds of patients , and most survived at the 12-month follow-up Introduction The purpose of this study was to evaluate if ultrasound derived measures of diaphragm thickening , rather than diaphragm motion , can be used to predict extubation success or failure . Methods Sixty-three mechanically ventilated patients were prospect ively recruited .  Diaphragm thickness ( tdi ) was measured in the zone of apposition of the diaphragm to the rib cage using a 7–10 MHz ultrasound transducer . The percent change in tdi between end-expiration and end-inspiration ( Δtdi% ) was calculated during either spontaneous breathing ( SB ) or pressure support ( PS ) weaning trials . A successful extubation was defined as SB for > 48 h following endotracheal tube removal . Results Of the 63 subjects studied , 27 patients were weaned with SB and 36 were weaned with PS . The combined sensitivity and specificity of Δtdi%≥30 % for extubation success was 88 % and 71 % , respectively . The positive predictive value and negative predictive value were 91 % and 63 % , respectively . The area under the receiver operating characteristic curve was 0.79 for Δtdi% . Conclusions Ultrasound measures of diaphragm thickening in the zone of apposition may be useful to predict extubation success or failure during SB or PS trials BACKGROUND Predictor indexes are often included in weaning protocol s and may help the intensive care unit ( ICU ) staff to reach expected weaning outcome in patients on mechanical ventilation . OBJECTIVE The objective of this study is to evaluate the potential of weaning predictors during extubation . DESIGN This is a prospect i ve clinical study . SETTING S The study was conducted in 3 medical-surgical ICUs . PATIENTS Five hundred consecutive unselected patients ventilated for more than 48 hours were included . METHODS AND MEASUREMENTS All patients were extubated after 30 minutes of successful spontaneous breathing trial and followed up for 48 hours . The protocol evaluated hemodynamics , ventilation parameters , arterial blood gases , and the weaning indexes frequency to tidal volume ratio ; compliance , respiratory rate , oxygenation , and pressure ; maximal inspiratory pressure ; maximal expiratory pressure ; Pao(2)/fraction of inspired oxygen ; respiratory frequency ; and tidal volume during mechanical ventilation  and in the 1st and 30th minute of spontaneous breathing trial . RESULTS Reintubation rate was 22.8 % , and intensive care mortality was higher in the reintubation group ( 10 % vs 31 % ; P < .0001 ) . The areas under the receiver operating characteristic curve showed that tests did not discriminate which patients could tolerate extubation . CONCLUSION Usual weaning indexes are poor predictors for extubation outcome in the overall ICU population INTRODUCTION : The extubation period is one of the most challenging aspects for intensive care teams . Timely recognition of the return to spontaneous ventilation is essential for reducing costs , morbidity , and mortality . Several weaning predictors were studied in an attempt to evaluate the outcome of removing ventilatory support . The purpose of this study was to analyze the predictive performance of the modified integrative weaning index ( IWI ) in the extubation process . METHODS : A prospect i ve study was performed in an ICU in a public hospital in Porto Alegre , Brazil , with 59 adult medical-surgical beds . The final population of the study comprised 153 patients receiving mechanical ventilation for over 48 h who were extubated during the period from February to November 2011 . Demographic data and clinical parameters were collected in addition to extubation predictors , including static compliance of the respiratory system , ratio of breathing frequency to tidal volume , tracheal airway-occlusion pressure 0.1 s after the start of inspiratory flow , and modified IWI . RESULTS : Extubation failure was observed in 23 of the subjects ( 15 % ) . Subjects with greater positive fluid balance , lower hemoglobin levels , and lower levels of bicarbonate presented a higher rate of reintubation . The 3 modified IWI values ( the first and 30th minute of the spontaneous breathing trial and the difference between them ) , as well as the other ventilatory parameters and extubation predictors , displayed poor extubation outcome discrimination accuracy . All indexes presented small areas under the receiver operating characteristic curve , and no accurate cutoff point was identified . CONCLUSIONS : We concluded that modified IWI , similar to other extubation predictors , does not accurately predict extubation failure BACKGROUND The need for reintubation after extubation and discontinuation of mechanical ventilation is not uncommon and is associated with increased mortality . Noninvasive positive-pressure ventilation has been suggested as a promising therapy for patients with respiratory failure after extubation , but a single-center , r and omized trial recently found no benefit . We conducted a multicenter , r and omized trial to evaluate the effect of noninvasive positive-pressure ventilation on mortality in this clinical setting . METHODS Patients in 37 centers in eight countries who were electively extubated after at least 48 hours of mechanical ventilation and who had respiratory failure within the subsequent 48 hours were r and omly assigned to either noninvasive positive-pressure ventilation by face mask or st and ard medical therapy . RESULTS A total of 221 patients with similar baseline characteristics had been r and omly assigned to either noninvasive ventilation ( 114 patients ) or st and ard medical therapy ( 107 patients ) when the trial was stopped early , after an interim analysis . There was no difference between the noninvasive-ventilation group and the st and ard-therapy group in the need for reintubation ( rate of reintubation , 48 percent in both groups ; relative risk in the noninvasive-ventilation group , 0.99 ; 95 percent confidence interval , 0.76 to 1.30 ) . The rate of death in the intensive care unit was higher in the noninvasive-ventilation group than in the st and ard-therapy group ( 25 percent vs. 14 percent ; relative risk , 1.78 ; 95 percent confidence interval , 1.03 to 3.20 ; P=0.048 ) , and the median time from respiratory failure to reintubation was longer in the noninvasive-ventilation group ( 12 hours vs. 2 hours 30 minutes , P=0.02 ) . CONCLUSIONS Noninvasive positive-pressure ventilation does not prevent the need for reintubation or reduce mortality in unselected patients who have respiratory failure after extubation We have previously shown ( Am . J. Respir . Crit . Care Med . 1995;152:1248 - 1255 ) that in patients needing mechanical ventilation  , the load imposed on the inspiratory muscles is excessive relative to their neuromuscular capacity . We have therefore hypothesized that weaning failure may occur because at the time of the trial of spontaneous breathing there is insufficient reduction of the inspiratory load . We therefore prospect ively studied patients who initially had failed to wean from mechanical ventilation ( F ) but had successful weaning ( S ) on a later occasion . Compared with S , during F patients had greater intrinsic positive end-expiratory pressure ( 6 . 10 + /- 2.45 versus 3.83 + /- 2.69 cm H2O ) , dynamic hyperinflation ( 327 + /- 180 versus 213 + /- 175 ml ) , total resistance ( Rmax , 14.14 + /- 4.95 versus 11.19 + /- 4.01 cm H2O/L/s ) , ratio of mean to maximum inspiratory pressure ( 0.46 + /- 0.1 versus 0.31 + /- 0.08 ) , tension time index ( TTI , 0.162 + /- 0.032 versus 0.102 + /- 0.023 ) and power ( 315 + /- 153 versus 215 + /- 75 cm H2O x L/min ) , less maximum inspiratory pressure ( 42.3 + /- 12.7 versus 53.8 + /- 15.1 cm H2O ) , and a breathing pattern that was more rapid and shallow ( ratio of frequency to tidal volume , f/VT 98 + /- 38 versus 62 + /- 21 breaths/min/L ) . To clarify on pathophysiologic grounds what determines inability to wean from mechanical ventilation , we performed multiple logistic regression analysis with the weaning outcome as the dependent variable . The TTI and the f/VT ratio were the only significant variables in the model . We conclude that the TTI and the f/VT are the major pathophysiologic determinants underlying the transition from weaning failure to weaning success OBJECTIVE To compare the respiratory rate to tidal volume ratio with the oxygen cost of breathing to see which could more accurately predict the outcome of  ventilator weaning for surgical patients . DESIGN Prospect i ve comparison of two modalities used to predict the likelihood of successful ventilator weaning . PATIENTS Twenty-eight consecutive patients with chronic respiratory insufficiency requiring long-term mechanical ventilation in the surgical intensive care unit at New Engl and Deaconess Hospital , Boston , Mass , were studied . MAIN OUTCOME MEASURES The oxygen cost of breathing and the respiratory rate to tidal volume ratio were measured during spontaneous breathing . Patients extubated within 2 weeks of being studied were design ated as extubated while patients not extubated within this period or requiring reintubation were recorded as not extubated . RESULTS The oxygen cost of breathing predicted successful extubation in all five patients who were extubated , and failure in 20 of 23 patients who could not be extubated ( sensitivity , 100 % ; specificity , 87 % ) . In contrast , the respiratory rate to tidal volume ratio predicted extubation for only two of five patients who were extubated and predicted failure in only 12 of 23 patients who could not be extubated ( sensitivity , 40 % ; specificity , 52 % ) . CONCLUSION For this group of patients requiring prolonged ventilation , the oxygen cost of breathing proved to be a more reliable predictor of both successful extubation and failure Objectives : To compare descriptors of the breath-to-breath respiratory variability during a 60-min spontaneous breathing trial in patients successfully and unsuccessfully separated from the ventilator and the endotracheal tube and to assess the usefulness of these predictors in discriminating these two categories of patients . Design : Prospect i ve observational study . Setting : Four general intensive care units in university hospitals . Patients : A total of 51 consecutive patients mechanically ventilated for > 24 hrs . Interventions : None . Measurements and Main Results : Tidal volume , respiratory period , inspiratory time , expiratory time , mean inspiratory flow ( tidal volume/inspiratory time ) , and duty cycle ( inspiratory time/respiratory period ) were obtained from the flow signal . Breath-by-breath variability was expressed in terms of their coefficients of variation ( CV ) , the number of breaths among which a significant correlation was found ( lag ) , and the autocorrelation coefficient between one breath and the following one . Five patients were excluded because of nonstationarity of the data , leaving 46 cases for analysis . Between-group comparison was conducted with the Mann-Whitney test , and a nonparametric classification and regression tree was used to identify variables discriminating “ success ” ( n = 32 ) and “ failure ” patients ( n = 14 ) . All coefficients of variation were significantly higher in success patients , who also exhibited significantly less respiratory autocorrelation ( shorter “ short memory ” ) . The classification and regression tree analysis allocated all success patients to a group defined by a coefficient of variation of tidal volume/inspiratory time of ≥19 % and a coefficient of variation of inspiratory time/respiratory period of ≥10 % that did not contain any failure patient . All failure patients belonged to a group with coefficient of variation of tidal volume/inspiratory time of < 19 % , a lag tidal volume of ≥11 , and that contained no success patient . Conclusions : In intensive care unit patients undergoing a spontaneous breathing trial , breathing variability is greater in patients successfully separated from the ventilator and the endotracheal tube . Variability indices are sufficient to separate success from failure cases STUDY OBJECTIVES To determine if minute ventilation ( E ) measured as a trend following the final weaning trial prior to extubation may identify patients ready for extubation and be useful as a predictive measure of extubation outcome . DESIGN Prospect i ve observational study . SETTING Community hospital medical/surgical ICU . PATIENTS Sixty-nine patients receiving mechanical ventilation enrolled in an ICU weaning protocol who underwent planned extubation during 6 months of prospect i ve evaluation . The failed extubation group included patients reintubated within 7 days . Patients were excluded if they received ventilation by noninvasive mask , bilevel positive airway pressure , tracheostomy , or were self-extubated . INTERVENTIONS Patients tolerating a spontaneous breathing trial ( SBT )  and ready for planned extubation were placed back on their pre-SBT ventilator setting s for up to 25 min , during which respiratory parameters were recorded . Respiratory parameters ( respiratory rate , tidal volume , E , rapid shallow breathing index [ f/VT ] ) were obtained at three time points : baseline ( pre-SBT ) , posttrial ( immediate conclusion of SBT ) , and recovery ( return to baseline ) . Patients were assumed to recover when E decreased to 110 % of the predetermined baseline . MEASUREMENTS AND RESULTS Fifty-nine patients were successfully extubated , and 10 patients required reintubation after 2.5 + /- 2.6 days ( mean + /- SD ) . Both groups were similar in age , comorbid status , primary diagnosis , APACHE ( acute physiology and chronic health evaluation ) II score , mode of weaning , and SBT length ( p > 0.1 ) . Respiratory parameters measured were similar at all three time points studied ( p > 0.1 ) . E recovery time of successful extubations was significantly shorter than failed extubations ( 3.6 + /- 2.7 min vs 9.6 + /- 5.8 min , p < 0.011 ) . Multiple logistic regression adjusted for age , sex , and severity of illness revealed that E recovery time was an independent predictor of extubation outcome ( p < 0.01 ) . The area under the receiver operating characteristic curve for E recovery time ( 0.85 + /- 0.07 ) was larger than that for baseline E , posttrial E , posttrial f/VT , or PaCO(2 ) . CONCLUSIONS E recovery time is an easy-to-measure parameter that may assist in determining respiratory reserve . Preliminary data demonstrates that it may be a useful adjunct in the decision to discontinue mechanical ventilation BACKGROUND Cardiovascular dysfunction has been reported as an important mechanism of weaning failure . Brain natriuretic peptide ( BNP ) is a sensitive and specific marker for cardiovascular dysfunction . OBJECTIVE To determine the value of BNP levels measured at initiation and end of a 2h spontaneous breathing trial ( SBT ) as a predictor of successful weaning of mechanical ventilation in patients with respiratory illness . PATIENTS AND METHODS Thirty consecutive patients ready for weaning were prospect ively enrolled in this cross-sectional analytic study over a 6-month period . All patients had been on spontaneous mode of weaning for at least 2h .  Tidal volume , respiratory rate , rapid shallow breathing index ( RSBI ) , minute ventilation and PaO2/FiO2 were observed at initiation of SBT .  BNP was measured at the initiation ( BNP1 ) and at the end of SBT ( BNP2 ) . Weaning failure is defined as either the failure of SBT or the need for reintubation within 48 h following extubation . RESULTS Out of the 30 included patients , 14 ( 46.6 % ) patients had failed weaning . PaCO2 and BNP2 were significantly higher in the patients with failed weaning as compared to those with successful weaning ( P = 0.025 , P = 0.031 respectively ) . However , BNP1 levels were not statistically significant between the 2 groups ( P = 0.722 ) . On multiple regression analysis , BNP% ( percent change in the BNP level during the 2-h SBT ) was the only predictor of weaning success . As compared to other weaning parameters , BNP% ≤ 14.9 had the best sensitivity , specificity , positive and negative predictive value . CONCLUSION Measuring the percentage change in the BNP level during a SBT may be a good predictor of weaning success from mechanical ventilation in respiratory patients OBJECTIVE To assess whether the respiratory rate to tidal volume ratio ( RVR ) measured while receiving automatic tube compensation ( ATC ) [ RVRATC ] would have a better predictive value as a weaning measure than unassisted RVR . DESIGN Prospect i ve cohort study . SETTING General ICU of a tertiary-care university hospital . PATIENTS Forty-three patients who received mechanical ventilation for > 24 h and were considered ready for weaning . INTERVENTIONS All patients underwent a 60-min spontaneous breathing trial ( SBT ) [ positive end-expiratory pressure of 5 cm H(2)O ; ATC , 100 % ] . Patients tolerating the trial ( n = 35 ) were extubated immediately . The following parameters were measured at the onset and end of the SBT : RVR , RVRATC , peak airway pressure ( Paw ) , airway occlusion pressure , and minute ventilation . The outcome measure was successful extubation ( ability to maintain spontaneous breathing for > 48 h ) . MEASUREMENTS AND RESULTS Median age was 55 years ( range , 25 to 88 years ) , median APACHE ( acute physiology and chronic health evaluation ) II score was 15.5 ( range , 3 to 29 ) , and median duration of mechanical ventilation prior to the SBT was 7 days ( range , 1 to 40 days ) .  Extubation was successful in 25 patients ( 72 % ) . There were no significant differences in baseline characteristics between patients successfully extubated ( group 1 ) and those requiring reintubation . On multivariate analysis , RVRATC measured at 60 min ( RVR(60)ATC ) was most predictive of successful extubation ( p = 0.03 ) . The area under the receiver operator characteristic curve was also highest for RVR(60)ATC ( 0.81 + /- 0.03 ) as compared to RVR ( 0.77 + /- 0.03 ) , RVRATC ( 0.75 + /- 0.04 ) , and RVR measured at 60 min ( 0.69 + /- 0.05 ) . The ratio of RVR(60)ATC to Paw was the best predictor ( 0.84 + /- 0.02 ) . CONCLUSIONS RVRATC measured at the end of the SBT was the best predictor of successful extubation . A new ratio ( ratio of RVRATC to Paw ) was most predictive and deserves further study OBJECTIVE To determine the frequency and effects of weaning-related myocardial ischemia on weaning outcomes in patients with coronary artery disease . DESIGN Prospect i ve cohort study . SETTING Medical and cardiac intensive care units of a 300-bed teaching community hospital . MEASUREMENTS AND MAIN RESULTS Three-lead ST segments , heart rate-systolic blood pressure products , and respiratory rate/tidal volume ratios were obtained for patients with coronary artery disease just before and during their initial trials of weaning from mechanical ventilation .  ST segments were interpreted by a blinded cardiologist . Eighty-three patients with a mean age of 72.4 + /- 1.1 years ( mean + /- SEM ) , a mean Acute Physiology and Chronic Health Evaluation II score of 16.4 + /- 0.8 , and a mean duration of mechanical ventilation of 4.6 + /- 0.9 days were studied . Eight patients showed electrocardiographic evidence of ischemia during weaning , and seven of these patients failed to be liberated on their first day of weaning . The presence of ischemia significantly increased the risk of weaning failure ( risk ratio , 2.1 ; 95 % confidence interval , 1.4 - 3.1 ) . The rate-pressure product for the group as a whole increased significantly during weaning , from 11.9 + /- 0.4 to 13.5 + /- 0.5 mm Hg x beats/min x 10(3 ) ( p < .01 ) . The increase in rate-pressure product tended to be greater in patients who became ischemic ( 12.8 + /- 0.9 to 17.3 + /- 2.0 mm Hg x beats/min x 10(3 ) ) than in patients who were not ischemic during weaning ( 11.8 + /- 0.4 to 13.0 + /- 0.5 mm Hg x beats/min x 10(3 ) ; p = .05 ) . The rate/volume ratio did not change significantly during weaning , but the rate/volume ratios after both 1 min ( 65.6 + /- 4.6 vs. 98.0 + /- 9.4 breaths/min/L ; p < .05 ) and 30 mins ( 68.6 + /- 4.3 vs. 91.1 + /- 8.9 breaths/min/L ; p < .05 ) of unassisted breathing were lower in successful than in unsuccessful patients . CONCLUSION Electrocardiographic evidence of myocardial ischemia occurs frequently and is associated with significantly increased risk of  first-day weaning failure in patients with coronary artery disease The duration of spontaneous breathing trials before extubation has been set at 2 h in research studies , but the optimal duration is not known . We conducted a prospect i ve , multicenter study involving 526 ventilator-supported patients considered ready for weaning , to compare clinical outcomes for trials of spontaneous breathing with target duration s of 30 and 120 min . Of the 270 and 256 patients in the 30- and 120-min trial groups , respectively , 237 ( 87.8 % ) and 216 ( 84.8 % ) , respectively , completed the trial without distress and were extubated ( p = 0.32 ) ; 32 ( 13.5 % ) and 29 ( 13.4 % ) , respectively , of these patients required reintubation within 48 h. The percentage of patients who remained extubated for 48 h after a spontaneous breathing trial did not differ in the 30- and 120-min trial groups ( 75.9 % versus 73.0 % , respectively , p = 0.43 ) . The 30- and 120-min trial groups had similar within-unit mortality rates ( 13 and 9 % , respectively ) and in-hospital mortality rates ( 19 and 18 % , respectively ) . Reintubation was required in 61 ( 13.5 % ) patients , and these patients had a higher mortality ( 20 of 61 , 32.8 % ) than did patients who tolerated extubation ( 18 of 392 , 4.6 % ) ( p < 0.001 ) . Neither measurements of respiratory frequency , heart rate , systolic blood pressure , and oxygen saturation during the trial , nor other functional measurements before the trial discriminated between patients who required reintubation from those who tolerated extubation . In conclusion , after a first trial of spontaneous breathing , successful extubation was achieved equally effectively with trials targeted to last 30 and 120 min Objective To examine the relationship of fluid balance and weaning outcomes . Methods We prospect ively collected demographic , physiological , daily fluid balance ( measured inputs minus outputs ) , and weaning data from 87 mechanically ventilated patients . Patients We examined 87 patients , a median age of 66 years , APACHE II of 22 , and performed 205 breathing trials ( BT ) ; 38 patients ( 44 % ) were successfully extubated after their first BT with minimal or no pressure support . Results Positive fluid balance ( inputs > outputs ) in the 24 , 48 , and 72 h and cumulatively ( from hospital admission ) prior to weaning were significantly greater in weaning failures than successes . Both univariate and multivariate analyses , adjusted for duration of mechanical ventilation and presence of chronic obstructive pulmonary disease , showed negative cumulative fluid balance 24 h prior to BTs ( OR=2.9 ) and cumulative fluid balance ( OR=3.4 ) to be independently associated with first-day weaning success . Similar relationships were demonstrated when all weaning attempts were analyzed . Negative fluid balance was as predictive of weaning outcomes as f/Vt ( likelihood of success was 1.7 for patients with negative fluid balance 24 h prior to weaning and 1.2 for those with f/Vt<100 min−1 l−1 ) . Although administration of diuretics was associated with more negative fluid balance , it was not independently associated with weaning outcomes . Conclusions These data suggest that fluid balance , a potentially modifiable factor , is associated with weaning outcomes . A r and omized study is required to determine whether diuresis to treat positive fluid balance expedites liberation from mechanical ventilation BACKGROUND After patients recovering from respiratory failure have successfully completed a spontaneous breathing trial ( SBT ) , clinicians must determine whether an artificial airway is still required . We hypothesized that cough strength and the magnitude of endotracheal secretions affect extubation outcomes . METHODS We conducted a prospect i ve study of 91 adult patients treated in medical-cardiac ICUs who were recovering from respiratory failure , had successfully completed an SBT , and were about to be extubated . A number of demographic and physiologic parameters were recorded with the patient receiving full ventilatory support and during the SBT , just prior to extubation . Cough strength on comm and was measured with a semi objective scale of 0 to 5 , and the magnitude of endotracheal secretions was measured as none , mild , moderate , or abundant by a single observer . In addition , patients were asked to cough onto a white card held 1 to 2 cm from the endotracheal tube ; if secretions were propelled onto the card , it was termed a positive white card test ( WCT ) result . All patients were then extubated from T-piece or continuous positive airway pressure breathing trials . If 72 h elapsed and patients did not require reintubation , they were defined as successfully extubated . RESULTS Ninety-one patients with a mean ( + /- SE ) age of 65.2 + /- 1.6 years , ICU admission APACHE ( acute physiology and chronic health evaluation ) II score of 17.7 + /- 0.7 , and duration of mechanical ventilation of 5.0 + /- 0.5 days were studied over 100 extubations . Sixteen patients could not be extubated , and 2 patients underwent two unsuccessful extubation attempts , for a total of 18 unsuccessful extubations . Age , severity of illness , duration of mechanical ventilation , oxygenation , rapid shallow breathing index , and vital signs during SBTs did not differ between patients with successful extubations vs patients with unsuccessful extubations . The WCT result was highly correlated with cough strength . Patients with weak ( grade 0 to 2 ) coughs were four times as likely to have unsuccessful extubations , compared to those with moderate-to-strong ( grade 3 to 5 ) coughs ( risk ratio [ RR ] , 4.0 ; 95 % confidence interval [CI],1.8 to 8.9 ) . Patients with moderate-to-abundant secretions were more than eight times as times as likely to have unsuccessful extubations as those with no or mild secretions ( RR , 8.7 ; 95 % CI , 2.1 to 35.7 ) . Patients with negative WCT results were three times as likely to have unsuccessful extubations as those with positive WCT results ( RR , 3.0 ; 95 % CI , 1.3 to 6.7 ) . Poor cough strength and endotracheal secretions were synergistic in predicting extubation failure ( Rothman synergy index , 3.7 ; RR , 31.9 ; 95 % CI , 4.5 to 225.3 ) . Patients with PaO(2)/fraction of inspired oxygen ( P : F ) ratios of 120 to 200 ( receiving mechanical ventilation ) were not less likely to be successfully extubated than those with P : F ratios of > 200 , but those with hemoglobin levels < or = 10 g/dL were more than five times as likely to have unsuccessful extubations as those with hemoglobin levels > 10 g/dL. CONCLUSIONS After patients recovering from respiratory failure have successfully completed an SBT , factors affecting airway competence , such as cough strength and amount of endotracheal secretions , may be important predictors of extubation outcomes . Also , a majority ( 89 % ) of medically ill patients with P : F ratios of 120 to 200 ( four of five patients with P : F ratios from 120 to 150 ) , values sometimes used to preclude weaning , were extubated successfully PURPOSE To determine if the ultimate ability of a long-term ventilated patient to wean can be predicted at the time of his or her admission to a long-term ventilator unit . DESIGN Two-phased prospect i ve study . SETTING Long-term ventilator facility , university-affiliated . SUBJECTS Adults ventilated for an average of 3 weeks , who did not have sepsis and who did not have chest tubes or progressive neurologic impairment . INTERVENTIONS On admission to the long-term ventilator unit , historic factors , ventilator history , and the following laboratory and metabolic tests were obtained : electrolytes , serum calcium , magnesium , and phosphorus , WBC , hemoglobin , albumin , total protein , transferrin , oxygen consumption , carbon dioxide production , respiratory quotient , and dead space/tidal volume . The patients were then placed in a weaning protocol utilizing increasing duration of pressure support ventilation during the day with complete rest at night . Forty-two days after enrollment in the study , representing three times the duration of the weaning protocol , the patients who successfully weaned were compared to those who remained ventilator dependent ( n = 20 ) . Patients who died or were transferred to another institution were excluded from this phase of the study , because we were trying to develop parameters that would be predictive of successful weaning . A parameter was considered to be predictive , and retained for the scoring system , if it produced at most 15 % false-positives and false-negatives . A score of 0 was then assigned to the threshold value that produced no false-positives ; 2 to the threshold value that produced no false-negatives and 1 to the intermediate values . The scoring system was then applied to a new prospect i ve group of patients ( n = 72 ) . MEASUREMENTS AND MAIN RESULTS Of all the parameters evaluated , only the following satisfied the false-positive and false-negative requirements ; static compliance , airway resistance , dead space to tidal volume ratio , PaCO2 , and frequency/tidal volume . Applying these , in the scoring system , to the initial group of patients , demonstrated that a score greater than 3 was associated with failure to wean ; a score less than 3 was associated with successful weaning , and a score of 3 was not predictive . Using these thresholds , the data were applied to the new prospect i ve group of patients , which again demonstrated that a score of greater than 3 was associated with failure to wean in all cases . A score less than 3 was again associated with successful weaning but there were two false-positives . The sensitivity , specificity , and positive predictive and negative predictive values for the scoring system were 1.0 , 0.91 , 0.83 , and 1.0 , respectively . None of the individual parameters included in the scoring system demonstrated equivalent statistical results . All but two of the patients who died prior to finishing the weaning period had weaning scores , which suggested that they would not be successfully weaned . CONCLUSIONS Parameters that are generally available , when combined into a scoring system , can predict at the time of admission to a long-term ventilator unit , in most cases , whether a patient will eventually wean . The scoring system result ed in no false-negatives and an acceptable number of false-positives . None of the individual parameters were as reliable as the scoring system as a whole PURPOSE To assess the accuracies of four commonly used parameters in predicting weaning outcome and whether breathing pattern changes during weaning . PATIENTS AND METHODS We prospect ively examined the predictive accuracies of four weaning parameters in mechanically ventilated patients in the medical and cardiac intensive care units of a 270-bed community teaching hospital . The spontaneous respiratory rate : tidal volume ratio ( RVRi ) , negative inspiratory force ( NIF ) , and spontaneous minute volume ( VE ) at the onset of weaning , and the  RVR  at 30 to 60 minutes of weaning ( RVR30 ) were measured . Weaning decisions were made by patients ' primary physicians independent of this study . Threshold values for computations of predictive values were as follows : RVR 100 < or = breaths per minute/L , NIF < or = -20 cm H2O , VE < or = 10 Lpm . Receiver operator curves were generated for each parameter . RESULTS One hundred medical/cardiac intensive care unit patients were studied . Their mean age was 64.6 + /- 15.8 years , mean APACHE II score of 15.8 + /- 6.7 and mean duration of mechanical ventilation before the study of 4.9 + /- 8.1 days .  RVRi sensitivity was 89 % , specificity was 41 % , positive predictive value was 72 % , negative predictive value was 68 % , and accuracy was 71 % . The RVR30 sensitivity was 98 % , specificity was 59 % , positive predictive value was 83 % , negative predictive value was 94 % , and accuracy was 85 % . Accuracies for the NIF and VE were 66 % and 62 % , respectively . The area under the receiver operator curve of the RVR30 ( 0.92 + /- 0.03 ) was higher than the RVRi ( 0.74 + /- 0.05 ) , NIF ( 0.68 + /- 0.06 ) and VE ( 0.54 + /- 0.06 ) ( p < 0.05 ) . CONCLUSIONS The RVR is more accurate than other commonly utilized clinical tools in predicting the outcome of weaning from mechanical ventilation . The RVR measured at 30 minutes is superior to the RVR in the first minute of weaning . The predictive accuracy and unique simplicity of the RVR justify its use in the care of mechanically ventilated patients Abstract Abstract Objective . To investigate the possibility of successful extubation performing a spontaneous breathing trial ( SBT ) in pressure support ventilation ( PSV ) with target duration s of 30 and 120 min . Design and setting . Prospect i ve and r and omized study in two medical-surgical adult intensive care units . Patients and participants . 98 adult patients supported by mechanical ventilation for at least 48 h and considered ready for a weaning trial . Interventions . An SBT conducted in PSV with 7 cmH2O and patients r and omly assigned to two groups with target duration s of 30- and 120-min . Measurements and results . In the 30-min group 43 patients ( 93 % ) tolerated the SBT and were extubated while 4 ( 9 % ) needed reintubation within 48 h ; in the 120-min group 46 patients ( 88 % ) successfully completed the trial and were extubated while 2 ( 4 % ) were reintubated . ICU mortality in the groups with short and long periods was 6 % and 4 % , and in-hospital mortality 20 % and 17 % , respectively . Those successful in the 30- and 120-min groups had similar length of ICU stay ( 6 and 7 days , respectively ) and in-hospital length of stay ( 20 and 25 days , respectively ) . Compared to the successfully extubated , the reintubated patients had significantly higher length of ICU stay and mortality ( 17 vs. 6 days and 33 vs. 3.6 % , respectively ) . Conclusions . An SBT with PSV of 7 cmH2O lasting 30 min is equally effective in recognizing the successfully extubated patients as a 120-min trial BACKGROUND The traditional predictors of the outcome of  weaning  from  mechanical ventilation -- minute ventilation ( VE ) and maximal inspiratory pressure (Plmax)--are frequently inaccurate . We developed two new indexes : the first quantitates rapid shallow breathing as the ratio of respiratory frequency to tidal volume ( f/VT ) , and the second is termed CROP , because it integrates thoracic compliance , respiratory rate , arterial oxygenation , and Plmax . METHODS The threshold values for each index that discriminated best between a successful and an unsuccessful outcome of weaning were determined in 36 patients , and the predictive accuracy of these values was then tested prospect ively in an additional 64 patients .  Sensitivity and specificity were calculated , and the data were also analyzed with receiver-operating-characteristic ( ROC ) curves , in which the proportions of true positive results and false positive results are plotted against each other for a number of threshold values of an index ; the area under the curve reflects the accuracy of the index . RESULTS Sensitivity was highest for Plmax ( 1.00 ) , followed closely by the f/VT ratio ( 0.97 ) . Specificity was highest for the f/VT ratio ( 0.64 ) and lowest for Plmax ( 0.11 ) . The f/VT ratio was the best predictor of successful weaning , and Plmax and the f/VT ratio were the best predictors of failure . The area under the ROC curve for the f/VT ratio ( 0.89 ) was larger than that under the curves for the CROP index ( 0.78 , P less than 0.05 ) , Plmax ( 0.61 , P less than 0.001 ) , and VE ( 0.40 , P less than 0.001 ) . CONCLUSIONS Rapid shallow breathing , as reflected by the f/VT ratio , was the most accurate predictor of failure , and its absence the most accurate predictor of success , in weaning patients from mechanical ventilation OBJECTIVE To establish whether any relationship exists between extubation outcome and sustained maximal inspiratory pressures ( SMIP ) . DESIGN AND SETTING Prospect i ve clinical study in the 7-bed general intensive care unit of a university hospital . SUBJECTS Twenty-seven intubated adults who were deemed ready for extubation were enrolled . MEASUREMENTS St and ard respiratory parameters and inspiratory muscle function data ( ie ,  SMIP and peak maximal inspiratory pressures [ MIP ] ) were recorded before extubation . RESULTS SMIP was found to be significantly greater in those who were successfully extubated than in those who underwent a failed extubation ( P < .01 ) . Receiver operating characteristic curves for SMIP data indicated that a cutoff point of 57.5 pressure time units would give a sensitivity and specificity of 1.0 for extubation outcome prediction . Peak MIP was also significantly greater in those successfully extubated ( P = .04 ) ; a cutoff point of 17.5 cm H(2)O gave a sensitivity of 1.0 and a specificity of 0.5 . CONCLUSIONS In this study , peak MIP was not specific enough to be clinical ly useful as a predictor of extubation outcome . SMIP was associated with extubation outcome with equally high sensitivity and specificity and may therefore have a role in outcome prediction OBJECTIVE To examine medical outcomes associated with reintubation for extubation failure after discontinuation of mechanical ventilation . DESIGN Prospect i ve cohort study of consecutive intubated medical ICU patients who underwent a trial of extubation at a tertiary-care teaching hospital . The failed extubation group consisted of all patients reintubated within 72 h or within 7 days ( if continuous ICU care had been required ) of extubation . All others were considered to be successfully extubated . Study end points included hospital death vs survival , the number of days spent in the ICU and in the hospital after the onset of mechanical ventilation , the likelihood of requiring > or = 7 or > or = 14 days of ICU care after extubation , and the need for transfer to either a long-term care or rehabilitation facility among the survivors . RESULTS Of 289 intubated patients , 247 ( 85 % ) were successfully extubated , and 42 ( 15 % ) required reintubation for failed extubation ( time to reintubation 1.5+/-0.2 days ) . Reintubation for extubation failure result ed in 12 additional days of mechanical ventilation . When compared with successfully extubated patients , reintubated patients were more likely to die in the hospital ( 43 % vs 12 % ; p<0.0001 ) , spend more time in the ICU ( 21.2+/-2.8 days vs 4.5+/-0.6 days ; p<0.001 ) and in the hospital ( 30.5+/-3.3 days vs 16.3+/-1.2 days ; p<0.001 ) after extubation , and require transfer to a long-term care or rehabilitation facility ( 38 % vs 21 % ; p<0.05 ) . Using multiple logistic regression , extubation failure was an independent predictor for death and the need for transfer to a long-term care facility . Compared with those successfully extubated , patients who failed extubation were seven times ( p<0.0001 ) more likely to die , 31 times ( p<0.0001 ) more likely to spend > or = 14 days in the ICU after extubation , and six times ( p<0.001 ) more likely to need transfer to a long-term care or rehabilitation facility if they survived . CONCLUSION After adjusting for severity of illness and comorbid conditions , extubation failure had a significant independent association with increased risk for death , prolonged ICU stay , and transfer to a long-term care or rehabilitation facility . Extubation failure may serve as an additional independent marker of severity of illness . Alternatively , poor outcomes may be etiologically related to extubation failure . If the latter proves to be the case , identifying patients at risk for poor outcomes from extubation failure and instituting alternative care practice s may reduce mortality , duration of ICU stay , and need for transfer to a long-term care facility
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