CONTINUOUS POSITIVE AIRWAY PRESSURE TREATMENT - EFFECTS ON GROWTH-HORMONE, INSULIN AND GLUCOSE PROFILES IN OBSTRUCTIVE SLEEP-APNEA PATIENTS

The principal nocturnal GH peak normally coincides with the first epis ode of slow wave sleep (SWS). Obstructive sleep apnea (OSA) patients h ave low nocturnal GH levels which may be explained by their poor quali ty fragmented sleep but other factors are possibly involved. Obesity i s frequently associated with OSA, and obese patients also manifest red uced GH secretion. The mechanisms reducing GH levels in obese subjects are not understood, but hyperinsulinaemia is a suggested factor. In t his study nocturnal plasma and secretory GH profiles of OSA patients w ere examined in relation to the quality and quantity of sleep, togethe r with plasma glucose and insulin levels' Eight OSA patients, (BMI 32. 7+/-2.3 kg/m2), underwent 2 night studies. For one night no treatment was given and for the other continuous positive airway pressure (CPAP) treatment was administered for the first time. Blood was collected co ntinuously throughout each night and plasma GH, insulin and glucose pr ofiles established in 10 min interval samples. From the plasma data a deconvolution model was used to calculate GH secretion rates. Sleep wa s recorded during the studies. For the non-treatment night GH levels w ere low and increased significantly with treatment, p=0.008 for plasma levels and p=0.02 for secretion rates. Treatment significantly decrea sed the cumulative apnea duration and increased the quantity of SWS an d Rapid Eye Movement (REM) sleep (p=0.008), but the mean insulin and g lucose profiles did not differ between the two nights. Individual GH p lasma and secretion rates, on treatment, showed a tendency to correlat e with the amount of SWS (p=0.09). This study demonstrated that in the se OSA patients restoration of SWS, rather than abnormalities in gluco se and insulin regulation to some extent explained the treatment effec ts on GH secretion.