ABSTRACT The onset of altitude‐induced central sleep apnea (CSA) varies among individuals and may be influenced by genetic factors affecting respiratory control. Tibetans, who have undergone high‐altitude adaptation over generations, may exhibit physiologic traits that protect against CSA. This study investigated the impact of Tibetan ancestry on respiratory control and hypoxia‐induced CSA. Nine healthy unacclimatized Tibetans living in Switzerland for at least 5 years and 20 Caucasians (all males; medianIQR age: 28 27–32 vs. 24 23.5–26 years; medianIQR BMI: 23.8 23.1–28 vs. 22.121.2–23.1kg/m 2 ) underwent two full polysomnographies, one at low altitude and one in a hypoxic chamber simulating 3500 m. The apnea‐hypopnea index (AHI) and the percentage of sleep spent in periodic breathing (PB) were calculated. A hyperoxic hypercapnic ventilatory response (HCVR) test and hypoxic ventilatory response tests at rest (HVRr) and during exercise (HVRe) were performed. Parameters were compared between groups using non‐parametric tests. At simulated altitude, Tibetans exhibited a significantly lower AHI (51.2 12.7–72.1/h vs. 107.0 36.7–140.3/h; p = 0.0231) and spent less sleep time in PB (27.6 2.6–44.5% vs. 58.8 14.0–89.0%; p = 0.0334) compared to Caucasians. HCVR did not differ significantly between groups (Tibetans: 1.983 1.349–2.224 L/min/mmHg; Caucasians: 2.227 1.698–3.071 L/min/mmHg; p = 0.2167). Tibetans showed a significantly lower HVRr (Tibetans: 0.001 −0.211–0.074 L/min/%/kg; Caucasians: 0.384 0.160–0.637 L/min/%/kg; p = 0.0112) and a blunted HVRe (Tibetans: 0.311 0.225–0.789 L/min/%/kg; Caucasians: 0.806 0.518–1.196 L/min/%/kg; p = 0.0448). These results indicate that Tibetan ancestry is associated with a partial protection from hypoxia‐induced central sleep apnea, likely related to a blunted hypoxic ventilatory response. These findings suggest that inherited differences in ventilatory control may modulate breathing stability during sleep at high altitude.
Heiniger et al. (Tue,) studied this question.