Influence of hypoxic ventilatory response on arterial O2 saturation during maximal exercise in acute hypoxia

The aim of this study was to evaluate the influence of peripheral chemosensitivity estimated by hypoxic ventilatory response (HVR) on arterial oxygen saturation (S_aO₂) during maximal exercise in acute hypoxia. A group of 16 healthy men performed maximal exercise in two conditions of partial pressure of inspired oxygen (P_IO₂/149 and 70 mm Hg, 19.8 and 9.3 kPa). Measurements of maximal oxygen uptake () andS_aO₂ using an ear-oximeter were carried out in both conditions ofP_IO₂. The HVR was measured at rest by progressive isocapnic hypoxia and evaluated by the slope of the linear regression between the ventilatory flow () and theS_aO₂ (). The absolute value of HVR (in litres per minute per percentage saturation per kilogram) was correlated to maximal expired (r = 0.85,P < 0.001), ventilatory equivalent for CO₂ (r = 0.83,P < 0.001) andS_aO₂ (r = 0.60,P < 0.05) determined during maximal exercise in hypoxia: a significant decrease in (37%) andS_aO₂ (32%) forP_IO₂ of 70 mm Hg (9.3 Pa) was observed (P < 0.001). The correlation between the decline of and arterial oxygen desaturation failed to reach statistical significance (r = 0.47, P = 0.1). The present findings indicated that the peripheral ventilatory chemosensitivity contributed to the interindividual variability of andS_aO₂ during maximal exercise in acute hypoxia.