IntroductionIndexes predicting weaning outcome are frequently inaccurate. We developed a new integrative weaning index aimed at improving the accuracy of the traditional indexes.MethodsThree hundred and thirty-one patients mechanically-ventilated for more than 24 hours were evaluated. Initially, the threshold values of each index that best discriminate between a successful and an unsuccessful weaning outcome were determined in 115 patients. In the second phase, the predictive performance of these values was tested prospectively in the other 216 patients. Frequency/tidal volume ratio (f/Vt ratio), tidal volume (Vt), tracheal airway occlusion pressure 0.1 s (P 0.1), the product of P 0.1 and f/Vt (P 0.1 × f/Vt), respiratory rate (f), static compliance of the respiratory system (Cst,rs), ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2 ratio) and the new integrative weaning index IWI (Cst,rs × arterial oxygen saturation/f/Vt ratio) were evaluated in all patients. The readiness for weaning and the decision to return to mechanical ventilation was made by the physician in charge, based on the signs of poor tolerance. The receiver operating characteristic (ROC) curves were calculated in order to evaluate the predictive performance of each index. The Bayes' theorem was used to assess the probability of each test of predicting weaning.ResultsIn the prospective-validation set, successful weaning was observed in 183 patients (84.7%) and weaning failure in 33 (15.27%). IWI presented the highest accuracy, with the area under the ROC curves larger than that under the curves for the f/Vt ratio (0.96 × 0.85 respectively; P = 0.003), and also larger than that under the curves for the other indexes. IWI presented a higher probability of successful weaning when the test was positive (0.99) and a lower probability when the test was negative (0.14). Measurement of Cst,rs during the weaning process was considered one of the study limitations.ConclusionsIWI was the best predictive performance index of weaning outcome and can be used in the intensive care unit setting.Trial Registrationcontrolled-trials.com ISRCTN92117906

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Introduction Noninvasive ventilation is a safe and eff ective method to treat acute respiratory failure, minimizing the respiratory workload and oxygenation. Few studies compare the effi cacy of diff erent types of noninvasive ventilation interfaces and their adaptation. Objective To identify the most frequently noninvasive ventilation interfaces used and eventual problems related to their adaptation in critically ill patients. Methods We conducted an observational study, with patients older than 18 years old admitted to the intensive care and step-down units of the Albert Einstein Jewish Hospital that used noninvasive ventilation. We collected data such as reason to use noninvasive ventilation, interface used, scheme of noninvasive ventilation used (continuously, periods or nocturnal use), adaptation, and reasons for nonadaptation. Results We evaluated 245 patients with a median age of 82 years (range of 20 to 107 years). Acute respiratory failure was the most frequent cause of noninvasive ventilation used (71.3%), followed by pulmonary expansion (10.24%), after mechanical ventilation weaning (6.14%) and sleep obstructive apnea (8.6%). The most frequently used interface was total face masks (74.7%), followed by facial masks in 24.5% of the patients, and 0.8% used performax masks. The use of noninvasive ventilation for periods (82.4%) was the most common scheme of use, with 10.6% using it continuously and 6.9% during the nocturnal period only. Interface adaptation occurred in 76% of the patients; the 24% that did not adapt had their interface changed to improve adaptation afterwards. The total face mask had 75.5% of interface adaptation, the facial mask had 80% and no adaptation occurred in patients that used the performax mask. The face format was the most frequent cause of nonadaptation in 30.5% of the patients, followed by patient's related discomfort (28.8%), air leaking (27.7%), claustrophobia (18.6%), noncollaborative patient (10.1%), patient agitation (6.7%), facial trauma or lesion (1.7%), type of mask fi xation (1.7%), and 1.7% patients with other causes. Conclusion Acute respiratory failure was the most frequent reason for noninvasive ventilation use, with the total face mask being the most frequent interface used. The most common causes of interface nonadaptation were face format, patient-related discomfort and air leaking, showing improvement of adaptation after changing the interface used. P2 Exercise training reduces oxidative damage in skeletal muscle of septic rats