THE EFFECT OF A VERY-LOW-CALORIE DIET-INDUCED WEIGHT-LOSS ON THE SEVERITY OF OBSTRUCTIVE SLEEP-APNEA AND AUTONOMIC NERVOUS FUNCTION IN OBESE PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA SYNDROME

The aim of this study was to examine the effect of a very low-calorie diet (VLCD)-induced weight loss on the severity of obstructive sleep a pnoea (OSA), blood pressure and cardiac autonomic regulation in obese patients with obstructive sleep apnoea syndrome (OSAS). A total of 15 overweight patients (14 men and one woman, body weight 114 +/- 20 kg, age 52 +/- 9 years, range 39-67 years) with OSAS were studied prospect ively. They were advised to follow a 2.51-3.35 MJ (600-800 kcal) diet daily for a 3-month period. In the beginning of the study, the patient s underwent nocturnal sleep studies, autonomic function tests and 24-h electrocardiograph (ECG) recording. In addition, 15 age-matched, norm al-weight subjects were studied. They underwent the Valsalva test, the deep-breathing test and assessment of heart rate variability at rest. The sleep studies and autonomic function tests were repeated after th e weight loss period. There was a significant reduction in weight (114 +/- 20 kg to 105 +/- 21 kg, P<0.001), the weight loss being 9.2 +/- 4 .0 kg (range 2.3-19.5 kg). This was associated with a significant impr ovement in the oxygen desaturation index (ODI4) during sleep (31 +/- 2 0-19 +/- 18, P<0.001). Before the weight loss the OSAS patients had si gnificantly higher blood pressure (150 +/- 18 vs. 134 +/- 20, P<0.05, for systolic blood pressure, 98 +/- 10 vs. 85 +/- 13, P<0.05, for dias tolic blood pressure) and heart rate (67 +/- 10 beats min(-1) vs. 60 /- 13, P<0.05) at rest than the control group. They had also lower bar oreflex sensitivity (4.7 +/- 2.8 ms mmHg(-1) vs. 10.8 +/- 7.1 ms mmHg( -1), P<0.01). During the weight reduction, the blood pressure declined significantly, and the baroreflex sensitivity increased by 49%. In co nclusion, our experience shows that weight loss with VLCD is an effect ive treatment for OSAS. Weight loss improved significantly sleep apnoe a and had favourable effects on blood pressure and baroreflex sensitiv ity that may have prognostic implications.