9 and less than 1 is highly accurate; and area under the curve of

9 and less than 1 is highly accurate; and area under the curve of 1 is a perfect test.In the prospective validation set, the prevalence of weaning success and weaning failure was calculated. The likelihood ratio of a positive test (LR+) and www.selleckchem.com/products/FTY720.html the likelihood ratio of a negative test (LR-) were calculated for each index. Likelihood ratios between 0.5 and 2.0 indicate that the weaning parameter is associated with small changes in the post-test probability of success or failure. Likelihood ratios from 2 to 5 and from 0.3 to 0.5 correlate with small but potentially important changes in probability, while ratios from 5 to 10 or 0.1 to 0.3 correlate with more clinically important changes in probability. Ratios higher than 10 or lower than 0.1 correlate with very large changes in probability [21].

We used Bayes’ theorem to assess the performance of each test in predicting weaning outcome as a function of the prevalence of weaning success or failure in the prospective validation-set [14]. Bayes’ theorem allows the calculation of success or failure of weaning after the performance of a test (post-test probability) [21].ResultsThree hundred and thirty-one patients were evaluated, 115 in a training set and 216 in a prospective-validation set. In the training set and prospective-validation set, successful weaning was observed in 94 (81.7%) and 183 (84.7%) patients, respectively. In the training set, 17 (81%) of the 21 weaning failure patients did not tolerate the SBT, while 4 (19%) completed the SBT, but required reintubation within the following 48 hours after extubation (extubation failure).

In the prospective-validation set, 27 (82%) of the 33 weaning failure patients did not tolerate the SBT, while 6 (18%) completed the SBT, but required reintubation within the following 48 hours after extubation (extubation failure). In the total population, weaning failure was observed in 54 of 331 patients (16.35%, including 10 reintubated patients, 4 of whom died).Clinical characteristics of the patients in the training set, prospective-validation data set and total population are shown in Table Table1.1. In the prospective-validation set, the prevalence of weaning success was 0.85 (183/216), and weaning failure was 0.15 (33/216). In the entire study, the prevalence of weaning success was 0.83 (277/331), and weaning failure was 0.16 (54/331).

Table 1Clinical characteristics, incidence of successful weaning and weaning failure, and the cause of acute respiratory failure in the training set, prospective-validation data set and in the total populationIn training set, the threshold values of each index that best discriminate between successful or unsuccessful weaning were: PaO2/FiO2 ratio of 255 or more; Cst,rs of 30 ml/cmH2O or more; IWI of 25 ml/cmH2O breaths/minute/liter or more; P 0.1 of 3.1 cmH2O or less; f of 30 breaths/minute AV-951 or less; Vt of 315 ml or more; f/Vt ratio of 100 breaths/minute/liter or less; and P 0.

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