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Therapeutics

Noninvasive weaning from mechanical ventilation reduced mortality from nosocomial pneumonia

ACP J Club. 1998 Nov-Dec; 129:65. doi:10.7326/ACPJC-1998-129-3-065


Source Citation

Nava S, Ambrosino N, Clini E, et al. Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to chronic obstructive pulmonary disease. A randomized controlled trial. Ann Intern Med. 1998 May 1;128:721-8.


Abstract

Question

For chronic obstructive pulmonary disease (COPD), is noninvasive weaning more effective than invasive weaning for liberating patients from invasive mechanical ventilation?

Design

Multicenter, randomized, controlled trial.

Setting

Respiratory intensive care units in 3 hospitals in Italy.

Patients

50 patients (mean age 68 y) with acute exacerbation of COPD requiring mechanical ventilation in whom a T-piece weaning trial failed 48 hours after intubation. Patients were excluded if they had such conditions as pneumonia, acute cardiac diseases, hemodynamic instability, neurologic diseases, sepsis, or trauma or if they were recovering from surgery.

Intervention

After failure of T-piece weaning, patients were ventilated in pressure support mode until previous PaCO2 and pH values were reached and respiratory rate was ≤ 30 breaths/min. Patients were allocated to noninvasive pressure support ventilation by face mask (n = 25) or to continued invasive pressure support ventilation (n = 25). In the noninvasive group, pressure support was adjusted to achieve a respiratory rate < 25 breaths/min and then was decreased by 2 or 4 cm H2O/d as tolerated. At least 2 spontaneous breathing trials of increasing duration were attempted each day. In the invasive group, pressure support was gradually decreased and trials of spontaneous breathing were done twice daily using a T-piece circuit or a continuous-flow circuit with a continuous positive-airway pressure < 5 cm H2O.

Main outcome measures

Mortality at 60 days, incidence of nosocomial pneumonia, and duration of mechanical ventilation and stay in the intensive care unit.

Main results

Patients who were weaned using noninvasive ventilation had lower mortality at 60 days (8% vs 28%, P = 0.009, assessed using a mortality table) and a lower incidence of nosocomial pneumonia (0% vs 28%, {P = 0.002}*) than patients weaned using invasive ventilation. The noninvasive group also had a shorter duration of mechanical ventilation (10.2 vs 16.6 d, P = 0.021) and stay in the intensive care unit (15.1vs 24.0 d, P = 0.005).

Conclusion

In patients with acute exacerbation of chronic obstructive pulmonary disease, a noninvasive approach to weaning from mechanical ventilation was associated with lower mortality and nosocomial pneumonia and a shorter duration of mechanical ventilation and intensive care unit stay than an invasive approach.

Source of funding: No external funding.

For correspondence: Dr. S. Nava, Division of Pneumology, Centro Medico di Riabilitazione di Montescano, 27040 Montescano (PV), Italy. FAX 39-385-61386.

*P value calculated from data in article.


Commentary

This innovative randomized trial evaluated the use of noninvasive ventilation as a weaning modality for patients with COPD exacerbation. To decide whether the reported benefits of noninvasive ventilation as a mode of weaning from invasive ventilation exceed the risks, several points need to be considered. First, generalizability may be limited because the patients studied had acute exacerbations of COPD but did not have concomitant severe diseases, such as pneumonia. Second, all patients were treated with neuromuscular blockers during the first 6 to 8 hours and weaning was attempted in all patients within 48 hours of intubation. Both of these practices may be more aggressive than those used in other settings and may have influenced the success rates in the 2 groups. Third, bias may have occurred because the caregivers and researchers were not blinded to the intervention and several subjective criteria were used to assess failure to wean. Finally, nose abrasion, which was severe in some cases, needs to be considered as a minor complication of noninvasive ventilation.

Clinical practice is seldom changed by 1 randomized controlled trial, and additional experimental evidence is needed to obtain more precise estimates of benefit and harm associated with the use of noninvasive ventilation for weaning from life support. Nava and colleagues did a cost-minimization analysis of noninvasive mechanical ventilation compared with invasive mechanical ventilation when these modalities were used from the onset of ventilation (1). Although no difference was shown in cost or caregiver time during the first 48 hours, noninvasive ventilation was less time-consuming in a subset of patients who were followed for the entire period of mechanical ventilation. Whether these fiscal conclusions apply when this modality is used for weaning should be studied.

Peter Dodek, MD
St. Paul's HospitalVancouver, British Columbia, Canada

Peter Dodek, MD
St. Paul's Hospital
Vancouver, British Columbia, Canada


Reference

1. Nava S, Evangelisti I, Rampulla C, et al. Human and financial costs of noninvasive mechanical ventilation in patients affected by COPD and acute respiratory failure. Chest. 1997;111:1631-8.