[Periodic breathing during sleep at high altitudes in patients with bronchial asthma]

Earlier we found that asthmatic patients treated at a high altitude sanatorium (3.200 m) had numerous episodes of arterial blood desaturation during the night. To investigate if periodic breathing (PB) was responsible for those episode we studied 5 asthmatics (A) (mean age 34 yrs) and 3 healthy controls (C) (mean age 28 yrs) using MESAM 4, a simple, portable system recording breathing sounds, heart frequency, arterial blood saturation and body position. A and C subjects were first investigated at low altitude (760 m). There was no PB at 760 m in either group. At high altitude MESAM 4 recordings were performed on the 2nd and the 7th night after the ascent. On the 2nd night in the A group subjects the number of PB cycles averaged 37.2 (22-54) occupying 3.2% (2-5%) of estimated sleep time. The number of no-PB episodes was 52.4 (23-109). In the C group subjects the number of PB cycles was 83.6 (10-147) occupying 9% (1-14%) of estimated sleep time. The number of no-PB episodes averaged 45.6 (6-84). On the 7th night in A the number of PB cycles was 46.6 (15-69) occupying 4% (1-7%) of estimated sleep time. The number of no-PB was 54.8 (13-147). In C the number of PB cycles averaged 29.3 (12-59) occupying 3.3% (2-6%) of estimated sleep time. The number of no-PB was 20.3 (9-37). We conclude that majority of desaturations during sleep in asthmatics at altitude of 3.200 m was not related to PB; the mechanisms of these desaturations require more investigations.