Overnight prescription of oxygen in long term oxygen therapy: time to reconsider the guidelines?

Mitzi Nisbet ¹, Tam E Eaton ^1*, Chris A Lewis ¹, Wendy Fergusson ¹ and John Kolbe ¹

¹ Auckland City Hospital, New Zealand

^* To whom correspondence should be addressed. E-mail: teaton{at}adhb.govt.nz.

Accepted 19 May 2006

Abstract

Background: Guidelines for long term oxygen therapy (LTOT) recommend increasing oxygen flow by 1 L/min overnight. The aims of this study of COPD patients on LTOT were to determine the prevalence of overnight desaturation if the usual oxygen flow rate is not increased at night, whether resting oxygen saturation predicts overnight desaturation, and whether overnight desaturation correlates with health-related quality of life (HRQL) and sleep quality.

Methods: A cross-sectional prospective study of consecutive patients with COPD on LTOT attending our regional outpatient oxygen service was undertaken. All patients fulfilled standard criteria for LTOT, had been established on LTOT at a flow to achieve resting oxygen saturations >90%, but had not been instructed to increase oxygen flow overnight. Overnight desaturation was defined as <90% for 30% of the night on either of two consecutive nights. HRQL was evaluated with the SF-36 Health Survey Questionnaire, Chronic Respiratory Questionnaire and the Pittsburgh Sleep Quality Index.

Results: Thirty-eight patients were evaluated; 63% male, mean (SD) age 73.5 (8.04) years, FEV1 0.77 (0.35) L. Overnight desaturation occurred in 6 (16%; 95% CI 4 to 27). Desaturators compared to non-desaturators had mean resting oxygen saturation on room air of 88% (4.2) versus 90% (4.1), p=0.15 and corrected saturations of 93% (2.0) versus 94% (2.0), p=0.18. HRQL and sleep quality were poor but did not differ between desaturators and non-desaturators.

Conclusions: The majority of patients did not exhibit overnight desaturation despite not increasing their LTOT prescription overnight. These results challenge the recommendation of routinely increasing overnight oxygen flow in LTOT patients.

Keywords: COPD, LTOT, guidelines, overnight oxygen saturation, sleep quality

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