The Impact of Obesity on Oxygen Desaturation during Sleep-disordered Breathing

Abstract

Rationale: Obesity increases the risk and severity of sleep-disordered breathing. The degree to which excess body weight contributes to blood oxygen desaturation during hypopneic and apneic events has not been comprehensively characterized. Objectives: To quantify the association between excess body weight and oxygen desaturation during sleep-disordered breathing. Methods: A total of 750 adult participants in the Wisconsin Sleep Cohort Study were assessed for body mass index (BMI) (kg/m 2 ) and sleep-disordered breathing. The amount of Sa O 2 , duration, and other characteristics of 37,473 observed breathing events were measured during polysomnography studies. A mixed-effects linear regression model estimated the association of blood oxygen desaturation with participant-level characteristics, including BMI, gender, and age, and event-level characteristics, including baseline Sa O 2 , change in VT, event duration, sleep state, and body position. Measurements and Main Results: BMI was positively associated with oxygen desaturation severity independent of age, gender, sleeping position, baseline Sa O 2 , and event duration. BMI interacted with sleep state such that BMI predicted greater desaturation in rapid eye movement (REM) sleep than in non-REM sleep. Each increment of 10 kg/m 2 BMI predicted a 1.0% (SE, 0.2%) greater mean blood oxygen desaturation for persons in REM sleep experiencing hypopnea events associated with 80% VT reductions. Conclusions: Excess body weight is an important predictor of the severity of blood oxygen desaturation during apnea and hypopnea events, potentially exacerbating the impact of sleep-disordered breathing in obese patients.Keywords: sleep apnea; overweight; hypoxia Obesity is one of the most important risk factors for sleepdisordered breathing (SDB) (1). Epidemiological studies have shown that the prevalence of SDB is strongly associated with excess body weight (2) and that weight gain independently predicts the development of SDB (3). Moreover, most (4), but not all (5), interventional studies have shown that weight loss is effective in reducing apneas and hypopneas. As the prevalence of obesity increases across industrialized nations, it is predicted that obesity will cause a corresponding increase in the prevalence of SDB (1, 6).The frequency of apneas and hypopneas increases with obesity (3, 7). The frequency of breathing events is an important predictor of the consequences of SDB, with a longitudinal doseresponse relationship between the apnea-hypopnea index (AHI) and the prevalence of cardiovascular morbidity (8). The severity of oxygen desaturation during obstructive breathing events and the cumulative burden of nocturnal hypoxia are important factors in this relationship; they also predict cardiovascular morbidity in patients with SDB, independent of the frequency of breathing events (9, 10). Because excess body weight is known to predispose to more severe oxygen desaturation during voluntary apneas (11), obese patients with SDB may be disadvantaged by greater oxygen desatu...

Comparison of the association with sleep apnoea of obesityversusinsulin resistance

“…These findings are contrary to data suggesting a linear relationship between excess weight and AHI in men [11], and an inverse relationship between BMI and oxygen desaturation [12,13]. An unequivocal explanation for the differences in results is not available, but these studies differed from ours in that the BMI range was broader, individuals with comorbidities were not excluded, and the impact of insulin resistance was not assessed.…”

High Hypopnea/Apnea Ratio (HAR) in Extreme Obesity

“…11,12 Scoring rule changes that have been made over the years which place less emphasis on arousals and more emphasis on oxygen desaturations may lead to leaner patients with OSAHS having fewer or less severe oxygen desaturations with scorable hypopneas when compared to obese patients, presumably related to less ventilation/perfusion mismatch and higher functional residual capacity in the leaner patients, although they still present with the other cardinal features of flow reduction and arousal. This possibility is reflected in the fact that in our study the oxygen saturation nadir was significantly lower in the more obese Group B subjects.…”

Positive Association between Altitude and Suicide in 2584 U.S. Counties

“…If the mechanism of the suicide-altitude relationship were hypoxia, we would anticipate that there may be increased mood disturbances at high altitude in those with sleep apnea (Peppard et al, 2009) or moderate or heavy smokers at high altitude.…”

“…Should the association not be present in some other locations with comparable variation in altitude, it is possible that our findings are owing to conditions that are more common in the United States. For example, although obesity rates are rising worldwide, they have been high in the United States for decades (Peppard et al, 2009). Obesity is known to cause increased hypoxia owing to sleep apnea and thereby may create a mood disturbance (Rigby et al, 2004); one might anticipate that the altitudesuicide finding might be heightened in obese individuals.…”