Comparison of the acute effects on gas exchange of nasal ventilation and doxapram in exacerbations of chronic obstructive pulmonary disease. Effect of doxapram on obstructive sleep apnea.
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.
                Patients admitted with acute exacerbations of COPD and type 2 respiratory failure (Pao2 < 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.
                In nine patients who received NIPPV the arterial PaO2 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 Pao2 in patients on NIPPV was accompanied by a fall in Paco2 but, in contrast, in those who received doxapram there was no improvement in Paco2.
                NIPPV may be more effective than doxapram in the management of acute ventilatory failure complicating COPD. To determine whether treatment with a respiratory stimulant, doxapram hydrochloride, would improve obstructive sleep apnea, we administered the drug to four patients with this disease. Subjects were given a bolus of doxapram, 0.5 mg X kg-1 lean body mass, followed by a 1 mg X min-1 infusion throughout the night on one night and placebo another night. Doxapram produced improvement in the average oxyhemoglobin desaturation during apneic and hypopneic episodes and decreased average apnea length, but did not change the average number of oxyhemoglobin desaturations per hour of sleep or sleep efficiency. We conclude that doxapram, when administered at levels known to increase ventilatory drive, does not decrease the number of disordered breathing events during sleep but does cause termination of these events at higher levels of oxyhemoglobin saturation.
Doxapram can improve blood gas exchange over the first few hours of treatment. Newer techniques such as non-invasive ventilation may prove to be more effective, although there is no randomised trial evidence to this effect.