Abstract de conférence
Résumé : Introduction:The Concordia station in Antarctica, situated at an equivalent altitude of 3800 meters, offers an ideal setting to study sleep disturbances due to hypobaric hypoxia. Previous research at Concordia showed a high incidence of periodic breathing and central apnea. While polysomnography is the standard for diagnosing sleep apnea, it may disturb normal sleep, is expensive, and requires expertise. Recent clinical studies have shown that time-domain heart rate variability (HRV) parameters during wakefulness are associated with the severity of obstructive sleep apnea, especially in moderate to severe cases. This study aims to assess the applicability of HRV in investigating sleep disturbances induced by hypobaric hypoxia.Methods:Our study involved 10 healthy male crew members assigned to a 12-month mission at the Concordia station. Electrocardiography data (500 Hz) was collected three months before the mission, during the second month of arrival, and in the 8th and 10th months on-site. Participants followed a breathing protocol consisting of 10 cycles of 10-second breathing. These data were then compared to those of 15 male subjects during a winter-over at a sea-level Antarctic station, as well as to those of 15 male patients with chronic sleep apnea. HRV analysis was conducted using Kubios HRV software (version 4.1.1, Kubios Oy, Kuopio, Finland). Statistical analyses were performed using linear mixed effects models for within-group comparisons and the Kruskal-Wallis test for between-group comparisons. Sidak and Dunn’s methods were applied to correct for repeated measurements, respectively. The significance level was set at p < 0.05. The results are expressed as median [first quartile, third quartile].Results:In the second month of their stay at high-altitude in Antarctica, the crew members exhibited significantly reduced time-domain HRV compared to baseline measures: RMSSD decreased from 50 [36, 54] ms² to 28 [16, 40] ms² (p = 0.03), PNN20 decreased from 63% [55%, 69%] to 50% [24%, 57%] (p = 0.04), and deceleration capacity decreased from 75 [61, 83] ms to 32 [24, 58] ms (p = 0.01). Notably, these changes were no longer present by the sixth month of winter-over. During the second month at Concordia, the subjects displayed time-domain variations of HRV reaching similar values as those observed in patients with sleep apnea, while significant differences were noted when compared to a sea-level control group: RMSSD during the beginning of the winter-over at Concordia was not different from the one of patients (p = 0.99) but was lower than in the control group at sea-level (p = 0.02). Similar changes were observed with the others markers of vagal activity investigated (p<0.05).Conclusions:The changes observed in the second month after arrival in high-altitude dissipate by the 8th month, suggesting a potential adaptation. Additionally, individuals exposed to high-altitude environments, at least in the first 2 months, exhibit time-domain HRV patterns similar to those observed in patients with chronic obstructive sleep apnea. This finding may be linked to the previously reported high incidence of central apnea at Concordia. As these HRV features reflect parasympathetic activity, we hypothesize that sleep apnea not only reduces parasympathetic activity during sleep, as previously demonstrated, but also during slow breathing in wakefulness. This could offer valuable insights into the severity of sleep apnea, particularly in regions with limited access to specialists and healthcare facilities, such as extreme environments.

Documents en relation

DI-fusion