Lack of gender difference in ventilatory chemoresponsiveness and post-hypoxic ventilatory decline

Altered chemoresponsiveness has been postulated to explain the gender difference in the incidence of sleep disordered breathing (SDB). The purpose of this investigation was to ascertain a gender difference in the effect of hypocapnic hypoxia on ventilation. Hypocapnic hypoxia was induced in stable NREM sleep for 3 min periods. In the first analysis, hypoxic ventilatory response in a steady state (SHVR) was defined as the amount of change in minute ventilation (VI) between mean room air (RA) and hypoxia divided by the change in Sa O2 between RA and hypoxia (DeltaVI/DeltaSa O2). The mean group SHVR values were 0.23+/-0.15 and 0.20+/-0.10 L/min per %SaO2, for men and women, respectively (P = ns). In the second analysis, we analyzed the decline in ventilatory parameters after the cessation of hypoxia. There was no difference in VI between the genders (men, 5.6+/-1.7 L/min vs. women, 4.9+/-1.9 L/min, P = ns). We conclude that the gender difference in SDB is not explained by a difference in the ventilatory response to hypocapnic hypoxia.