Nocturnal efficiency and tolerance of a demand oxygen delivery system in COPD patients with nocturnal hypoxemia.

ABSTRACT

OBJECTIVES: We compared the efficacy of the standard nasal cannula and the demand oxygen delivery system (DODS) during sleep in patients with COPD. SUBJECTS: Twenty patients with moderate or severe COPD were included in the study. METHODS: Four consecutive polysomnographic recordings were performed under the following conditions DODS powered by compressed air (night 1 [N1]); oxygen delivered with a nasal cannula alone (night 2 [N2]); oxygen delivered through a DODS (night 3 [N3]); and oxygen delivered with nasal cannula alone (night 4 [N4]). Oxygen flow rates with and without DODS were adjusted the day before the first night so that the resulting transcutaneous arterial oxygen saturation (SaO2) was > or = 95%. The following parameters were evaluated each night apnea-hypopnea index, nocturnal SaO2, total oxygen saving, and several neurophysiologic parameters. RESULTS: The oxygen saving with the DODS was, on average, 60%. All parameters obtained during N2 and N4 (oxygen alone) were identical. The percentage of total recording time spent at SaO2 > or = 95% was comparable between N2 ([mean +/- SD]; 69+/-32%) and N3 (61+/-31%) (difference is not significant [NS]), as was the time spent at SaO2 between 90% and 95% (N2, 29.8+/-31%; N3, 35.9+/-27%; NS) and < 90% (N2, 0.75+/-2.6%; N3, 2.5+/-8.6%; NS). Although the mean response time was not significantly different between N2 and N3, two patients experienced a substantial increase in response time with an SaO2 < 90% on the DODS. The DODS device did not induce any difference in the percentage of time spent in rapid eye movement (REM) sleep (N2, 12.3+/-8.7%; N3, 16.4+/-7.8%; NS) or non-REM sleep (N2, 87.7+/-8.7%; N3, 83.7+/-7.9%; NS). Non-REM distribution in stage 1-2 sleep and in stage 3-4 sleep was comparable between N2 and N3. Similarly, no difference was observed for the sleep efficiency index (N2, 71+/-15%; N3, 69.6+/-14%; NS). Differences between sleep onset latency times were NS. CONCLUSIONS: In a majority of moderate to severe COPD patients, the use of a DODS device does not induce any significant alteration of nocturnal neurophysiologic and ventilatory profiles. However, the presence of nocturnal desaturation in a few patients justifies the need to systematically perform a ventilatory polygraphic recording when prescribing a DODS device.