title: Exaggerated respiratory chemosensitivity and association with SaO2 level at 3568 m in obesity.
abstract: To investigate whether obesity is associated with alterations in respiratory chemosensitivity, we compared the ventilatory response to hypoxia (HVR) and hypercapnia (HCVR) in 9 obese men (BMI: 37.0+/-4.3 kg m(-2)) and 10 lean men (BMI: 25.8+/-4.8 kg m(-2)). HVR (DeltaVE, L min(-1) per DeltaSaO2, %) was measured by a progressive isocapnic hypoxia technique, and HCVR (DeltaVE/DeltaPETCO2, L min(-1)Torr(-1)) was measured by a progressive hypercapnic method. HCVR, was greater (p<0.001) in the obese men (2.68+/-0.78) than in the lean men (1.4+/-0.45) as was HVR (p<0.05) (1.26+/-0.65 versus 0.71+/-0.43, respectively). The difference (DeltaSaO2, 4.30+/-3.69 and 10.54+/-3.45 in the lean and obese men, respectively, p<0.01) between daytime (86+/-1 and 86+/-1%) and nighttime SaO2 (81+/-3 and 76+/-4%) at a simulated altitude of 3658 m was significantly (p<0.05) correlated with both HVR (r=0.51) and HCVR (r=0.48). These results suggest that chemosensitivity in mildly obese men is increased, not blunted. Furthermore, otherwise healthy, obese individuals have the potential for significant desaturation during sleep at high altitude possibly due to exaggerated sleep-disordered breathing.
authors.affiliation: Research Center for High Altitude Medicine, Qinghai Medical College, 16 Kunlun Road, Xining, Qinghai 180001, PR China.
authors.forename: Ri-Li
authors.initials: RL
authors.lastname: Ge
authors.forename: J A
authors.initials: JA
authors.lastname: Stone
authors.forename: B D
authors.initials: BD
authors.lastname: Levine
authors.forename: T G
authors.initials: TG
authors.lastname: Babb
mesh_terms: D000064:Acclimatization / Q000502:physiology; D000328:Adult; D000532:Altitude Sickness / Q000378:metabolism / Q000503:physiopathology*; D015992:Body Mass Index; D016022:Case-Control Studies; D002628:Chemoreceptor Cells / Q000378:metabolism*; D006801:Humans; D006935:Hypercapnia / Q000209:etiology; D000860:Hypoxia / Q000209:etiology; D016014:Linear Models; D008297:Male; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood*; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods; D016192:Resting Phase, Cell Cycle / Q000502:physiology; D012890:Sleep / Q000502:physiology
chemical_list: D010100:Oxygen