Resting energy expenditure among patients with obstructive sleep apnea syndrome: The impact of a single CPAP application

Abstract

Rationale: Data on the impact of obstructive sleep apnea syndrome (OSAS) and its treatment on resting energy expenditure (REE) are currently few and conflicting. The purpose of the present study was to investigate, for the first time, the impact of a single nasal continuous positive airway pressure (CPAP) application on REE among OSAS patients. Material-Methods: This is a retrospective analysis of prospectively collected data. A population of male patients with OSAS recently confirmed with nocturnal polysomnography, who returned to the Sleep Clinic in order to undergo a single-night CPAP titration, constituted the study population. All patients underwent REE measurement with indirect calorimetry, right before and after CPAP application. Apnea-hypopnea index (AHI) during CPAP was used to discriminate responders (AHI<5/h) from non-responders (AHI≥5/h). Paired samples t-test was used for group comparisons. Level of p<0.05 was considered significant. Results: 62 patients with OSAS (100% male; age: 46.5±11.4 years; AHI without nasal CPAP: 49.4±19.1) constituted the study population. 38 patients (47.5±10.2 years old) were grouped as responders, while the rest 24 (45±13.1 years old; p=0.410) as non-responders. Among responders, REE values were similar, either they were measured before or after sleep (1969.5±517.8 kcal vs 1881±671.5 kcal; p=0.372). On the contrary, REE values measured before sleep were significantly higher from those after sleep, among non-responders (2312.8±1622.1 kcal vs 1881.8±973 kcal; p=0.009). Conclusion: A single nasal CPAP application in OSAS patients diminishes the differences in REE values before and after sleep, but only among responders.