IMPORTANCE Daily spontaneous breathing trials (SBTs) are the best approach to determine whether patients are ready for disconnection from mechanical ventilation, but mode and duration of SBT remain controversial. OBJECTIVE To evaluate the effect of an SBT consisting of 30 minutes of pressure support ventilation (an approach that is less demanding for patients) vs an SBT consisting of 2 hours of T-piece ventilation (an approach that is more demanding for patients) on rates of successful extubation. DESIGN, SETTING, AND PARTICIPANTS Randomized clinical trial conducted from January 2016 to April 2017 among 1153 adults deemed ready for weaning after at least 24 hours of mechanical ventilation at 18 intensive care units in Spain. Follow-up ended in July 2017. INTERVENTIONS Patients were randomized to undergo a 2-hour T-piece SBT (n = 578) or a 30-minute SBT with 8-cm H 2 O pressure support ventilation (n = 557). MAIN OUTCOME AND MEASURES The primary outcome was successful extubation (remaining free of mechanical ventilation 72 hours after first SBT). Secondary outcomes were reintubation among patients extubated after SBT; intensive care unit and hospital lengths of stay; and hospital and 90-day mortality. RESULTS Among 1153 patients who were randomized (mean age, 62.2 [SD, 15.7] years; 428 [37.1%] women), 1018 (88.3%) completed the trial. Successful extubation occurred in 473 patients (82.3%) in the pressure support ventilation group and 428 patients (74.0%) in the T-piece group (difference, 8.2%; 95% CI, 3.4%-13.0%; P = .001). Among secondary outcomes, for the pressure support ventilation group vs the T-piece group, respectively, reintubation was 11.1% vs 11.9% (difference, −0.8%; 95% CI, −4.8% to 3.1%; P = .63), median intensive care unit length of stay was 9 days vs 10 days (mean difference, −0.3 days; 95% CI, −1.7 to 1.1 days; P = .69), median hospital length of stay was 24 days vs 24 days (mean difference, 1.3 days; 95% CI, −2.2 to 4.9 days; P = .45), hospital mortality was 10.4% vs 14.9% (difference, −4.4%; 95% CI, −8.3% to −0.6%; P = .02), and 90-day mortality was 13.2% vs 17.3% (difference, −4.1% [95% CI, −8.2% to 0.01%; P = .04]; hazard ratio, 0.74 [95% CI, 0.55-0.99]). CONCLUSIONS AND RELEVANCE Among patients receiving mechanical ventilation, a spontaneous breathing trial consisting of 30 minutes of pressure support ventilation, compared with 2 hours of T-piece ventilation, led to significantly higher rates of successful extubation. These findings support the use of a shorter, less demanding ventilation strategy for spontaneous breathing trials.

Eric Newsholmes laboratory was the first to show glutamine utilization by lymphocytes and macrophages. Recently, we have found that neutrophils also utilize glutamine. This amino acid has been shown to play a role in lymphocyte proliferation, cytokine production by lymphocytes and macrophages and phagocytosis and superoxide production by macrophages and neutrophils. Knowledge of the metabolic fate of glutamine in these cells is important for the understanding of the role and function of this amino acid in the maintenance of the proliferative, phagocytic and secretory capacities of these cells. Glutamine and glucose are poorly oxidized by these cells and might produce important precursors for DNA, RNA, protein and lipid synthesis. The high rate of glutamine utilization and its importance in such cells have raised the question as to the source of this glutamine, which, according to current evidence, appears to be muscle.

We conclude that in our study, the closed-tracheal suction system did not reduce VAP incidence, even for exogenous pneumonia.

One-hour rest after a successful SBT reduced the rates of reintubation within 48 h after extubation in critically ill patients. Trial registration Clinicaltrials.gov identifier NCT01915563.

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