Comparison of the acute effects on gas exchange of nasal ventilation and doxapram in exacerbations of chronic obstructive pulmonary disease

Background - Nasal intermittent positive pressure ventilation (NIPPV) is useful in exacerbations of chronic obstructive pulmonary disease (COPD) complicated by ventilatory failure, The effects of NIPPV were compared with those of the respiratory stimulant doxapram on gas exchange in patients with COPD and acute ventilatory failure. Methods - Patients admitted with acute exacerbations of COPD and type 2 respiratory failure (Pao(2) <8 kPa and PaCO2 >6.7 kPa) who did not improve with conventional treatment were randomised to receive either NIPPV or intravenous doxapram. Blood gas tensions were monitored for four hours. Results - In nine patients who received NIPPV the arterial Pao(2) improved from a mean (SE) of 5.9 (0.4) kPa to a maximum of 8.1 (0.6) kPa which was maintained at four hours. Eight patients who received doxapram had a similar baseline PaO2 of 5.6 (0.4) kPa which rose to a maximum of 7.3 (0.5) kPa but this was not maintained at four hours. The improvement in Pao(2) in patients on NIPPV was accompanied by a fall in PaCO2 but, in contrast, in those who received doxapram there was no improvement ill PaCO2. Conclusions - NIPPV may be more effective than doxapram in the management of acute ventilatory failure complicating COPD.