Effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation

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 cond ucted a prospective, multicenter study involving 526 ventilator-supported p atients considered ready for weaning, to compare clinical outcomes for tria ls of spontaneous breathing with target durations of 30 and 120 min. Of the 270 and 256 patients in the 30- and 120-min trial groups, respectively, 23 7 (87.8%) and 216 (84.8%), respectively, completed the trial without distre ss 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 pati ents who remained extubated for 48 h after a spontaneous breathing trial di d not differ in the 30- and 120-min trial groups (75.9% versus 73.0%, respe ctively, p = 0.43). The 30- and 120-min trial groups had similar within-uni t mortality rates (13 and 9%, respectively) and in-hospital mortality rates (19 and 18%, respectively). Reintubation was required in 61 (13.5%) patien ts, and these patients had a higher mortality (20 of 61, 32.8%) than did pa tients who tolerated extubation (18 of 392, 4.6%) (p < 0.001). Neither meas urements of respiratory frequency, heart rate, systolic blood pressure, and oxygen saturation during the trial, nor other functional measurements befo re the trial discriminated between patients who required reintubation from those who tolerated extubation. In conclusion, after a first trial of spont aneous breathing, successful extubation was achieved equally effectively wi th trials targeted to last 30 and 120 min.