title: High-altitude hypoxia and periodic breathing during sleep: gender-related differences.
abstract: High-altitude exposure is characterized by the appearance of periodic breathing during sleep. Only limited evidence is available, however, on the presence of gender-related differences in this breathing pattern. In 37 healthy subjects, 23 male and 14 female, we performed nocturnal cardio-respiratory monitoring in the following conditions: (1) sea level; (2) first/second night at an altitude of 3400 m; (3) first/second night at an altitude of 5400 m and after a 10 day sojourn at 5400 m. At sea level, a normal breathing pattern was observed in all subjects throughout the night. At 3400 m the apnea-hypopnea index was 40.3 ± 33.0 in males (central apneas 77.6%, central hypopneas 22.4%) and 2.4 ± 2.8 in females (central apneas 58.2%, central hypopneas 41.8%; P < 0.01). During the first recording at 5400 m, the apnea-hypopnea index was 87.5 ± 35.7 in males (central apneas 60.0%, central hypopneas 40.0%) and 41.1 ± 44.0 in females (central apneas 73.2%, central hypopneas 26.8%; P < 0.01), again with a higher frequency of central events in males as seen at lower altitude. Similar results were observed after 10 days. With increasing altitude, there was also a progressive reduction in respiratory cycle length during central apneas in males (26.9 ± 3.4 s at 3400 m and 22.6 ± 3.7 s at 5400 m). Females, who displayed a significant number of central apneas only at the highest reached altitude, were characterized by longer cycle length than males at similar altitude (30.1 ± 5.8 s at 5400 m). In conclusion, at high altitude, nocturnal periodic breathing affects males more than females. Females started to present a significant number of central sleep apneas only at the highest reached altitude. After 10 days at 5400 m gender differences in the apnea-hypopnea index similar to those observed after acute exposure were still observed, accompanied by differences in respiratory cycle length.
authors.affiliation: Department of Cardiology, S.Luca Hospital, Istituto Auxologico Italiano, IRCCS, Milan, Italy.
authors.forename: Carolina
authors.initials: C
authors.lastname: Lombardi
authors.forename: Paolo
authors.initials: P
authors.lastname: Meriggi
authors.forename: Piergiuseppe
authors.initials: P
authors.lastname: Agostoni
authors.forename: Andrea
authors.initials: A
authors.lastname: Faini
authors.affiliation: Department of Cardiology, S.Luca Hospital, Istituto Auxologico Italiano, IRCCS, Milan, Italy.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bilo
authors.forename: Miriam
authors.initials: M
authors.lastname: Revera
authors.forename: Gianluca
authors.initials: G
authors.lastname: Caldara
authors.forename: Marco
authors.initials: M
authors.lastname: Di Rienzo
authors.forename: Paolo
authors.initials: P
authors.lastname: Castiglioni
authors.forename: Bussotti
authors.initials: B
authors.lastname: Maurizio
authors.forename: Francesca
authors.initials: F
authors.lastname: Gregorini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Parati
mesh_terms: D056044:Actigraphy; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000008:administration & dosage / Q000494:pharmacology; D001274:Atmospheric Pressure; D001562:Benzimidazoles / Q000008:administration & dosage / Q000494:pharmacology; D001565:Benzoates / Q000008:administration & dosage / Q000494:pharmacology; D018660:Blood Pressure Monitoring, Ambulatory / Q000295:instrumentation; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D000860:Hypoxia / Q000150:complications* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation* / Q000592:standards; D010100:Oxygen / Q000097:blood; D010919:Placebos; D056152:Respiratory Rate / Q000502:physiology; D012720:Severity of Illness Index; D012737:Sex Factors; D012890:Sleep / Q000502:physiology*; D020182:Sleep Apnea, Central / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D000077333:Telmisartan; D013997:Time Factors
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D001562:Benzimidazoles; D001565:Benzoates; D010919:Placebos; D010100:Oxygen; D000077333:Telmisartan