Intermittent vs continuous hypoxia: effects on ventilation and erythropoiesis in humans

摘要: Objective Recently, we showed that 5 days of normobaric intermittent hypoxia at rest (IH; 2 hours daily 3800 m simulated altitude; partial pressure inspired oxygen 90 torr) can induce an increase in the isocapnic hypoxic ventilatory response (HVR) and blood reticulocyte count. The purpose present study was to compare these data with continuous exposure same level. Methods Four subjects were exposed, a year later, (CH), 4 different exposed 8 weeks CH, both White Mountain Research Station (3800 altitude, barometric ∼489 torr). Inspired minute ventilation ( V ˙ I ), end-tidal carbon dioxide, arterial saturation (Sao [sat]), hematocrit, hemoglobin concentration measured times during exposures. HVR expressed as per 1% decrease Sao . Results no significant difference control values 1 apart (IH, 0.06±0.03; CH 2d (2 days' hypoxia), 0.19±0.07 L·min −1 ·%sat ; means ± SE), similar after IH compared (0.42±0.26 0.51±0.22 , respectively). On new maximum increase, observed only IH, concentrations hematocrit significantly increased (45.0±2.7% vs 51.5±3.0% 14.5±0.7 17.2±1.0 g·dL did not change from week whereas hematological still increasing end weeks. Conclusion Changes sensitivity induced by are magnitude but occur time courses. effects on erythropoiesis fewer than CH.