The relationship between obstructive sleep apnoea and body mass index

Obese patients have a high prevalence of obstructive sleep apnoea (OSA), but a low response rate and high frequency of relapse after uvulopalatopharyngoplasty (UVPP). In this study we have determined the level of obstruction during sleep in 31 men with OSA, using a catheter with multiple micropressure transducers and a portable digital recorder. The proportion of apnoeic episodes with obstruction at lower levels correlated with increasing body mass index (BMI) (P < 0.05). Thus, with increasing obesity, there seems to be a shift to a lower level of obstruction. All patients with BMI > 30 and apnoea index (AI) > 5 had predominantly lower obstructions (P < 0.05). This may explain why many obese patients fail to respond, or have relapses after UVPP.