Pressure support ventilation versus bilevel positive airway pressure for acute exacerbation of chronic obstructive pulmonary disease: a randomized trial

Objectives

Noninvasive positive pressure ventilation (NPPV) is widely used in an attempt to reduce the need for endotracheal intubation and mechanical ventilation in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). However, few controlled studies have compared pressure support ventilation by face mask (PSV) to bilevel positive airway pressure (BiPAP™) in patients with acute exacerbation of COPD. This study aims to compare these two modes of NPPV in acute hypercapnic respiratory failure in order to reduce respiratory rate (RR) and PaCO₂ in an equivalent degree.

Method

Eleven consecutive adult patients admitted to the Critical Care Unit of Hospital Albert Einstein, São Paulo, Brazil, in acute respiratory failure due to exacerbation of COPD were randomized to receive PSV (n = 5) versus BiPAP™ (n = 6). Inclusion criteria were a high probability of acute exacerbation of COPD, RR above 24 breaths per minute, a PaCO₂ above 45 mmHg, and arterial pH below 7.35 but above 7.10. Pressure support was used initially at 15-20 cmH₂O (×=15.2 cmH₂O) delivered through a facemask with a microprocessed ventilator. The patients allocated to BiPAP™ group received initially inspiratory pressure through a facemask at 20-25 cmH₂O (×=21.3 cmH₂O). The device was adjusted in the S/T mode.Positive end-expiratory pressure was 5 cmH₂O. Oxygen was administered to provide an arterial oxygen saturation above 90%. The RR, arterial blood gases, arterial pressure, and heart rate were measured on admission, after 2 h, 6 h during NPPV, and 1 h after the patient was weaned.

Results

See Table.

Table

Discussion

NPPV is a commonly used therapy for the treatment of acute hypercapnic respiratory failure due to COPD exacerbation. The results reported here confirm the effectiveness of NPPV in improving COPD patients in acute respiratory failure. This is demonstrated by the significant fall in RR, the increase in oxygenation (not shown), and the fall in PaCO₂ despite neither PSV or BiPAP™ reduced PaCO₂ significantly. Comparing PSV and BiPAP™ both are effective.