Obstructive sleep apnoea in adults: body postures and weight changes interactions

The aim of this work was to study the relationship between changes of body posture dominance and changes of body weight overtime in adults with obstructive sleep apnoea. The participants were 112 non-treated adults with obstructive sleep apnoea who underwent two polysomnographic evaluations at our Sleep Disorders Unit during an average of 6.2 years interval. Positional patients having most of their breathing abnormalities in the supine posture and who became non-positional patients had a significant gain in weight and a significant increase in apnoeahypopnoea index, mainly in lateral apnoeahypopnoea index. On the contrary, non-positional patients who became positional patients had a significant decrease in weight (but less than the increase in weight of positional patients who became non-positional patients) and showed a significant improvement in apnoeahypopnoea index, again mainly in lateral apnoeahypopnoea index. These non-positional patients who became positional patients initially had a less severe disease, as judged by apnoeahypopnoea index, lateral apnoeahypopnoea index and minimum SaO2 during non-rapid eye movement sleep, and were less obese than non-positional patients who remained non-positional patients. The later were the patients who showed initially the worst disease and were more obese than the rest of the patients, and their condition did not change significantly over time. Non-positional patients who converted to positional patients showed a decrease in body weight and improvement of obstructive sleep apnoea, while positional patients who converted to non-positional patients showed an increase in body weight and worsening of obstructive sleep apnoea. It appears that weight changes have a modulatory effect on positional dominance, and lateral apnoeahypopnoea index appears to be a sensitive parameter of these changes.