A COMPARISON OF FOUR METHODS OF WEANING PATIENTS FROM MECHANICAL VENTILATION

Background. Weaning patients from mechanical ventilation is an important 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 mean ( SD) of 7.5 6.1 days and who were considered by their physicians to be ready for weaning. One hundred thirty patients had respiratory distress during a two-hour trial of spontaneous breathing. These patients were randomly assigned to undergo one of four weaning techniques: intermittent mandatory ventilation, in which the ventilator rate was 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 which pressure support was initially set at 18.0 6.1 cm of water and then reduced, if possible, by 2 to 4 cm of water at least twice a day (37 patients); intermittent trials of spontaneous breathing, conducted two or more times a day if possible (33 patients); or a once-daily trial of spontaneous breathing (31 patients). Standardized protocols were followed for each technique. Results. The median duration of weaning was 5 days for intermittent mandatory ventilation (first quartile, 3 days; third quartile, 11 days), 4 days for pressure-support ventilation (2 and 12 days, respectively), 3 days for intermittent (multiple) trials of spontaneous breathing (2 and 6 days, respectively), and 3 days for a once-daily trial of spontaneous breathing (1 and 6 days, respectively). After adjustment for other covariates, the rate of successful weaning was higher with a once-daily trial of spontaneous breathing than with intermittent mandatory ventilation (rate ratio, 2.83; 95 percent confidence interval, 1.36 to 5.89; P 0.006) or pressure-support ventilation (rate ratio, 2.05; 95 percent confidence interval, 1.04 to 4.04; P 0.04). There was no significant difference in the rate of success between once-daily trials and multiple trials of spontaneous breathing. Conclusions. A once-daily trial of spontaneous breathing led to extubation about three times more quickly than intermittent mandatory ventilation and about twice as quickly as pressure-support ventilation. Multiple daily trials of spontaneous breathing were equally successful. (N Engl J Med 1995;332:345-50.) From the Hospital Universitario de Getafe, Madrid (A.E., F.F., I.A., M.A.C.); Loyola University, Chicago, and Hines Veterans Affairs Hospital, Hines, Ill. (M.J.T.); Hospital del Mar (J.F.S.) and Hospital Santa Creu i Sant Pau (I.V., S.B.), Barcelona, Spain; Hospital Parc Tauli, Sabadell, Spain (R.F.); Hospital Germans Trias i Pujol, Badalona, Spain (R.T.); Complejo Hospitalario de León, León, Spain (D.C.); Hospital General de Segovia, Segovia, Spain (S.M.); and Hospital del Río Ortega, Valladolid, Spain (J.B.). Address reprint requests to Dr. Esteban at the Servicio de Cuidados Intensivos, Hospital Universitario de Getafe, Ctra. de Toledo km 12’500, 28905 Getafe, Madrid, Spain. Supported in part by a grant from the Veterans Affairs Research Service. *The other members of the Spanish Lung Failure Collaborative Group are listed in the Appendix. A LTHOUGH often lifesaving, mechanical ventilation causes numerous life-threatening complications, 1 making it important to discontinue ventilator support at the earliest possible time. More than 40 percent of the time that a patient receives mechanical ventilation is spent trying to wean the patient from the ventilator. 2 Considering the proportion of staff time devoted to weaning, it is surprising that the process continues to be managed empirically and that a standardized approach has not been developed. Weaning techniques differ considerably from one another. 3 Traditionally, intermittent trials of spontaneous breathing, conducted one or more times a day, have been used. Intermittent mandatory ventilation was introduced amid claims that it was superior to the traditional weaning approach. It allows the patient to breathe spontaneously between ventilator-delivered breaths 4 ; thus, weaning can be considered to begin with the institution of mechanical ventilation. In the 1980s, pressure-support ventilation became available 5 ; it provides a titratable pressure boost to every inspiratory effort, and weaning is accomplished by gradually decreasing the level of the pressure boost. Efficacy studies of weaning techniques can be faulted for having a retrospective design, inappropriate study The New England Journal of Medicine Downloaded from nejm.org at LOYOLA UNIVERSITY on August 8, 2012. For personal use only. No other uses without permission. Copyright © 1995 Massachusetts Medical Society. All rights reserved. 346 THE NEW ENGLAND JOURNAL OF MEDICINE Feb. 9, 1995 populations, and poorly standardized protocols; in addition, most were conducted before the use of pressuresupport ventilation became widespread. 6-8 Accordingly, we performed a prospective, randomized study involving patients who were deemed ready to discontinue mechanical ventilation. In a subgroup of patients who were difficult to wean we compared the length of time required for weaning with the use of four techniques: intermittent mandatory ventilation, pressure-support ventilation, intermittent trials of spontaneous breathing conducted several times a day, and a once-daily trial of spontaneous breathing.