Four subjects had improvement in symptoms during the oxygen month, and four had improvement during the placebo month. The two patients who showed the greatest reduction in apnea frequency with acute oxygen administration showed the greatest symptomatic improvement on placebo. There was, however, no change in mean sleep latency time from baseline to placebo to oxygen. Awake ventilation was reduced as evidenced by an increase in mean resting PaC02 from 40 ± 1 mm Hg to 43 ± 1 mm Hg on oxygen. Buy Asthma Inhalers Online
This was attributed to a chronic metabolic alkalosis induced by recurrent nocturnal respiratory acidosis. Any reduction in apnea frequency or improvement in percentage of time spent in apnea lasted only as long as the oxygen therapy. Cessation of nocturnal oxygen resulted in an immediate return to baseline apnea frequency and duration. The authors interpreted the lack of improvement in hypersomnolence after chronic oxygen administration to mean that factors such as recurrent arousals may be important determinants of hypersomnolence. This is an important study in that it examines the effect of home supplemental oxygen on sleep apnea and its symptoms in a manner similar to the method that would be used to administer home oxygen by most clinicians. Furthermore, objective methods (MSLT) were used to assess the effect of oxygen on daytime hypersomnolence.