Relationship between metabolic syndrome and hypercapnia among obese patients with sleep apnea

Impact of Body Composition on Sleep and Its Relationship with Sleep Disorders: Current Insights

Sleep is involved in many physiological processes and is essential for both physical and mental health. Obesity and sleep deprivation due to sleep disorders are major public health issues. Their incidence is increasing, and they have a wide range of adverse health-related consequences, including life-threatening cardiovascular disease. The impact of sleep on obesity and body composition is well-known, and many studies have shown an association between insufficient or excessive sleep duration and obesity, body fat percentage, and weight gain. However, there is growing evidence of the effects of body composition on sleep and sleep disorders (particularly sleep disordered breathing) through anatomical and physiological mechanisms (nocturnal fluid shift, core body temperature, or diet). Although some research has been conducted on the bidirectional effects of sleep-disordered breathing and body composition, the specific effects of obesity and body composition on sleep and the underlying mechanisms that explain these effects remain unclear. Therefore, this review summarizes the findings on the effects of body composition on sleep and draws conclusions and proposals for future research in this field.

Clinical, polysomnographic, and cephalometric features of obstructive sleep apnea with AHI over 100

PURPOSE

Obstructive sleep apnea (OSA) is induced by a sleep-related collapse of the upper airway in association with multiple factors. The severity of OSA is determined by the apnea-hypopnea index (AHI). Although obesity and sex differences are common factors in OSA, the level of the AHI varies to the same degree according to the age and sex and degree of obesity. However, only a few studies have evaluated AHI over 100/h, those reports did not describe why they set the AHI cutoff at 100/h. The purpose of this study was to elucidate the pathogenesis of "very" severe OSA, defined as having an AHI > 100/h.

METHODS

AHI > 100/h was set as very severe OSA (VS-OSA) in this study. As controls, moderate to severe OSA patients, matched with VS-OSA for age, sex, and body mass index (BMI), were enrolled. The findings of polysomnography and cephalography between VS-OSA and controls were compared.

RESULTS

Eleven patients in the VS-OSA group (mean AHI 110.2/h) and 22 patients in the control group (mean AHI 41.6/h) were compared (mean age 50.2 vs 50.6, male:female 5:6 vs 10:12, mean BMI 35.4 kg/m2 vs 34.5 kg/m2). There were no significant differences in the clinical characteristics. In the polysomnographic parameters, the VS-OSA group showed apnea predominance, the mean percutaneous oxygen saturation (SO2) was significantly lower in all sleep stages, and the minimum SO2 was significantly lower (49.0% vs 77.5%, p = 0.002). A similar apnea duration and rather shorter hypopnea duration were shown. The time of apnea-to-arousal was significantly earlier (- 0.1 s vs 0.9 s, p = 0.003). Lung-to-finger circulation time showed no differences. The cephalometric findings showed no significant differences.

CONCLUSIONS

VS-OSA patients were more likely to have apnea predominance, desaturation when sleeping despite a similar apnea duration, and rather shorter hypopnea duration, and arousals were evoked significantly earlier.