1. ¹Division de kinésiologie, Département de médecine sociale et préventive, Université Laval, Ste-Foy, Québec, Canada
2. ²Unité de recherche en pneumologie, Ste-Foy, Québec, Canada
3. ³Axe de recherche en obésité et métabolisme énergétique, Centre de recherche de l'Hôpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l'Université Laval, Ste-Foy, Québec, Canada

Correspondence: Dr A Tremblay, Division of Kinesiology, Department of Social and Preventive Medicine, Faculty of Medicine, Laval University, Ste-Foy, Québec, Canada, G1K 7P4. E-mail: angelo.tremblay@kin.msp.ulaval.ca

Received 5 February 2005; Revised 30 August 2005; Accepted 9 September 2005; Published online 1 November 2005.

Abstract

The purpose of this study was to investigate the possibility of a relationship between the severity of obstructive sleep apnea syndrome (OSAS) and adaptive thermogenesis. Daily energy expenditure (DEE) and sleeping metabolic rate (SMR) were measured in apneic and a priori nonapneic subjects who were tested in a whole-body indirect calorimetry chamber for 24 h. The apneic patients were diagnosed by nocturnal home oximetry to determine the percentage of total recording time spent below 90% arterial oxygen saturation (% TRT <90% SaO₂). Reference equations established from body weight and age in nonapneic subjects were used to predict DEE and SMR in apneic patients. The predicted values of the apneic patients were then compared to their measured values. No significant difference was found between predicted and measured values in SMR nor in DEE. We observed a significant relationship between the severity of nocturnal desaturation and the difference between predicted and measured DEE in apneic patients (r=-0.74, P<0.05) and a similar negative trend with SMR (r=-0.65, P=0.08). These preliminary data suggest that a nocturnal hypoxia may influence adaptive thermogenesis in apneic patients and complicate their body weight regulation.