Daily screening and breathing trials hastened the discontinuation of mechanical ventilation
ACP J Club. 1997 May-Jun;126:74. doi:10.7326/ACPJC-1997-126-3-074
Ely EW, Baker AM, Dunagan DP, et al. Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously. N Engl J Med. 1996 Dec 19:335;1864-9.
To determine whether the identification of patients who are likely to breathe spontaneously and subsequent feedback to physicians will promote earlier discontinuation of mechanical ventilation (MV) and reduce mortality, length of stay, costs, and complications.
Randomized controlled trial.
Medical and coronary intensive care units (ICUs) of a U.S. teaching hospital.
300 nonsurgical patients (mean age 61 y, 50% men) with respiratory failure. Exclusion criteria were age < 18 years, dependence on MV for ≥ 2 weeks, or existence of an extubation order. Follow-up was complete.
Daily screening of all patients (n = 149 in the intervention group, and n = 151 in the control group) was defined as positive if all of the following occurred: ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen > 200; positive end-expiratory pressure ≤ 5 cm of water; adequate cough during suctioning; ratio of respiratory frequency to tidal volume of < 105 breaths/min per liter (rapid, shallow breathing); and only intermittent use of sedatives or low-dose dopamine. Patients in the intervention group with a positive screening test were given a 2-hour trial of spontaneous breathing. The results of this trial, if successful, were given to the attending physicians in person or by telephone.
Main outcome measures
Duration of MV, time from a successful screening test to discontinuation of MV, and length of stay in the ICU. Secondary outcomes were death, hospital costs (U.S. dollars), length of hospitalization, and complications (need for reintubation within 48 h, removal of breathing tube by patient, tracheostomy, and MV for > 21 d).
Patients in the intervention group spent less time on MV (median 4.5 vs 6 d, P = 0.003), had a shorter weaning time (median 1 vs 3 d from successful screening to discontinuation of MV, P < 0.001), had fewer complications (20% vs 41%, P = 0.001), and incurred lower cost of care in the ICU (U.S. $15 740 vs $20 890, P = 0.03). The groups did not differ for mortality (38% vs 40%, P = 0.63), length of stay in the ICU (median 8 vs 9 d, P = 0.17) or the hospital (median 14 vs 15.5 d, P = 0.93), or total hospital costs ($26 229 vs $29 048, P = 0.3).
Daily screening of respiratory function with trials of spontaneous breathing for appropriate patients reduced the duration of MV and cost of intensive care in patients on MV but not total mortality or total hospital costs.
Source of funding: No external funding.
For article reprint: Dr. E.W. Ely, Section on Pulmonary and Critical Care, Department of Medicine, Bowman Gray School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA. FAX 910-716-7277. E-mail email@example.com.
Ely and colleagues notified physicians of patients in the intervention group who were deemed ready for ventilator weaning after tolerating a 2-hour trial of spontaneous breathing. Physicians who attended patients in the control group were not notified and therefore made the decision to begin weaning without this information. Simply notifying the attending physicians in the control group when patients met the screening criteria might have resulted in much more comparable outcomes in the groups. Further, although patients in the control group were screened, they did not have early spontaneous breathing trials. Esteban and colleagues (1) showed that daily spontaneous breathing trials resulted in more rapid discontinuation of MV than pressure support or intermittent mandatory ventilation styles of weaning. Thus, control group patients in the Ely study did not have the early "kick start" of spontaneous breathing trials.
Inexperienced physicians often have a great desire to begin weaning early in a patient's clinical course by decreasing the intermittent mandatory ventilation or pressure support ventilation. However, experience teaches that, although weaning may begin immediately or in 1, 2, or 6 days, success comes on the day that the clinical condition of the patient allows it, regardless of when the process starts. Patients with acute respiratory failure do not depend on us to wean them—they depend on us to treat their underlying illness and discontinue MV when appropriate.
In my view, screening of patients by the nursing and respiratory staff on a daily basis should become a routine part of the care of patients with acute respiratory failure. These professionals can then advise us that clinical conditions may permit discontinuing MV earlier than if we were left to our own devices.
Christopher M. Hughes, MD
Monongahela Valley HospitalMonongahela, Pennsylvania, USA