A COMPARISON OF 4 METHODS OF WEANING PATIENTS FROM MECHANICAL VENTILATION

Background. Weaning patients from mechanical ventilation is an importa nt problem in intensive care units. Weaning is usually conducted in an empirical manner, and a standardized approach has not been developed. Methods. We carried out a prospective, randomized, multicenter study involving 546 patients who had received mechanical ventilation for a m ean (+/-SD) of 7.5+/-6.1 days and who were considered by their physici ans to be ready for weaning. One hundred thirty patients had respirato ry distress during a two-hour trial of spontaneous breathing. These pa tients were randomly assigned to undergo one of four weaning technique s: intermittent mandatory ventilation, in which the ventilator rate wa s initially set at a mean (+/-SD) of 10.0+/-2.2 breaths per minute and then decreased, if possible, at least twice a day, usually by 2 to 4 breaths per minute (29 patients); pressure-support ventilation, in whi ch pressure support was initially set at 18.0+/-6.1 cm of water and th en reduced, it possible, by 2 to 4 cm of water at least twice a day (3 7 patients); intermittent trials of spontaneous breathing, conducted t wo or more times a day if possible (33 patients); or a once-daily tria l of spontaneous breathing (31 patients). Standardized protocols were followed for each technique. Results. The median duration of weaning w as 5 days for intermittent mandatory ventilation (first quartile, 3 da ys; third quartile, 11 days), 4 days for pressure-support ventilation (2 and 12 days, respectively), 3 days for intermittent (multiple) tria ls of spontaneous breathing (2 and 6 days, respectively), and 3 days f or a once-daily trial of spontaneous breathing (1 and 6 days, respecti vely). After adjustment for other covariates, the rate of successful w eaning was higher with a once-daily trial of spontaneous breathing tha n with intermittent mandatory ventilation (rate ratio, 2.83; 95 percen t confidence interval, 1.36 to 5.89; P<0.006) or pressure-support vent ilation (rate ratio, 2.05; 95 percent confidence interval, 1.04 to 4.0 4; P<0.04), There was no significant difference in the rate of success between once-daily trials and multiple trials of spontaneous breathin g. Conclusions. A once-daily trial of spontaneous breathing led to ext ubation about three times more quickly than intermittent mandatory ven tilation and about twice as quickly as pressure-support ventilation. M ultiple daily trials of spontaneous breathing were equally successful.