ABSTRACT
Introduction: This study aims to evaluate the incidence of Obstructive Sleep Apnoea (OSA) in severely obese Asians and to study the impact of weight loss on OSA. Materials and Methods: We report the results of routine preoperative Polysomnograms in 350 Asian patients undergoing bariatric surgery in our institute. Polysomnograms were repeated in 75 randomly selected patients with moderate to severe OSA after target weight loss with the laparoscopically placed adjustable gastric band (LAGB). Results: The prevalence of OSA in obese Asians is high. Moderate OSA was found in 46% of patients and severe OSA was found in 33%. Severe OSA was significantly more in the Chinese (46%) compared to the Malays (29%) or Indians (21%) (P = 0.035). We identified other risk factors for severe OSA (male sex, higher body mass index and the presence of hypertension) but were unable to select identifying parameters for very low (<5%) likelihood of severe OSA such that routine sleep studies prior to bariatric surgery could be omitted. Apnoea Hypoapnoea Index (AHI) showed improvement of 50% at 20 kg excess weight loss with the cure of OSA in preoperatively severe cases (P <0.005). Mild to moderate cases reported similar improvements although a direct correlation could not be established. Desaturation events, apnoea episodes, work of breathing and subjective assessment of sleepiness scores and quality of life (QOL) showed improving trends, albeit not statistically significant. Similar improvements were seen in sleep architecture with increased rapid eye movement (REM) and stage 3 sleep. Conclusions: The incidence of OSA in Asians undergoing bariatric surgery is high. Routine sleep studies in Asian patients are justified. Weight loss brought about a significant improvement in AHI and continuous positive airway pressure requirements. LAGB placement should be considered a broadly effective therapy for sleep apnoea in the severely obese patient.
The incidence of OSA in severely obese Asians is poorly documented. This is also compounded by a varied racial profile across Asia. Singapore, with its mixed ethnic population is uniquely poised to study the prevalence of sleep disturbances and the results of different interventions. In this study we sought to evaluate the prevalence of obstructive sleep apnoea (OSA) in bariatric surgical practice in Singapore and attempt to formulate guidelines for preoperative polysomnograms. We sought to evaluate any identifying parameters to predict a higher chance of having OSA or those with a very low likelihood of OSA such that routine preoperative polysomnograms could be avoided. Polysomnograms were repeated to evaluate the effects of surgically induced target weight loss on different aspects of sleep disordered breathing which has not been well described so far in the Asian setting.
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