ALMITRINE IMPROVES OXYGENATION WHEN BOTH AWAKE AND ASLEEP IN PATIENTS WITH HYPOXIA AND CARBON-DIOXIDE RETENTION CAUSED BY CHRONIC-BRONCHITIS AND EMPHYSEMA

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Abstract
Patients with chronic bronchitis and emphysema who are hypoxic when awake become more hypoxic during sleep, with a further rise in their preexisting pulmonary hypertension. Almitrine, a respiratory stimulant, improves arterial blood gas tensions in such patients when they are awake. A double-blind, placebo-controlled, cross-over study was used to compare the effects of 50 mg almitrine given orally twice a day for 14 days on O2 saturation (SaO2), respiratory movements and sleep quality in 9 patients with hypoxic chronic bronchitis and emphysema (FEV1 [forced expiratory volume], 0.4-1.0 l; PaO2 [arterial O2 tension], 51 .+-. (SEM [standard error of the mean]) 2 mm Hg; PaCO2 [arterial CO2 tension], 49 .+-. 1 mm Hg). Almitrine improved arterial blood gas tensions when awake, mean PaO2 rising by 8 mm Hg (P < 0.001) and PaCO2 falling by 4 mm Hg (P < 0.01). Almitrine improved noctural oxygenation, mean SaO2 [arterial O2 saturation] when awake rising from 83 .+-. 4% to 89 .+-. 3% (%P < 0.01), and the lowest SaO2 during sleep rising on average from 65 .+-. 6% to 77 .+-. 3% (P < 0.02). The number of hypoxemic episodes (SaO2 falling by .gtoreq. 10% from the preceding stable baseline during sleep) and the time when SaO2 was below 80% (135 .+-. 53 vs. 46 .+-. 35 min; P < 0.01) also improved. Almitrine did not improve sleep quality. Almitrine improves arterial gas tensions when awake and reduces the frequency and severity of nocturnal hypoxemia without impairing sleep quality in patients with chronic bronchitis and emphysema who are both hypoxemic and hypercapnic when awake. This improvement in nocturnal O2 saturation is related to the higher position on the O2 Hb dissociation curve when awake, before sleep, as a result of almitrine treatment.