Larry J. Findley

Effect of very-low-calorie diets with weight loss on obstructive sleep apnea

To determine the effect of very-low-calorie diets (VLCDs) with weight loss on obstructive sleep apnea (OSA), we studied eight obese subjects with OSA, five males and three females. Subjects consumed a VLCD of 1760 kJ (420 kcal) (67% protein, 4% fat, 29% carbohydrate) or 3350 kJ (800 cal) (20% protein, 30% fat, 50% carbohydrate) with 100% of the recommended daily allowance of vitamins and minerals. Mean (+/- SD) values of weight and respiration before and after weight loss were, for weight, 153 +/- 37 and 132 +/- 29 kg (P less than 0.05); for BMI (kg/m2), 54 +/- 13 and 46 +/- 10 (P less than 0.05); for desaturations/h sleep, 106 +/- 50 and 52 +/- 45 (P less than 0.05); for apneas + hypopneas/h sleep, 90 +/- 32 and 62 +/- 49; for Pco2, 48 +/- 10 and 42 +/- 4 torr (P less than 0.05). Desaturation episodes/h and apnea + hypopneas/h improved in six patients. The most obese subject (female, BMI 81) who lost the most weight (47 kg) did not improve, nor did the subject who lost the least weight, 7 kg. The number of movements + arousals from sleep decreased in all patients (P less than 0.05). We conclude that VLCD with weight loss can produce improvement in OSA; subjects who lose a small amount of weight or subjects who are extraordinarily obese before and after weight loss may not improve.

Treatment of obstructive sleep apnea with continuous nasal airflow.

Although nasal continuous positive airway pressure (CPAP) is effective therapy for obstructive sleep apnea (OSA), it requires a customfitted nasal appliance and large cumbersome tubing. We therefore designed and tested a new device (NFLOW) to deliver airflow to the nose of patients with OSA. We studied 13 patients the first night without treatment and the following night with NFLOW. The degree of sleep apnea was assessed by the number of desaturations per hour of sleep and the average maximum desaturation per episode. Treatment with NFLOW significantly decreased all parameters (P<0.01) in 9 patients (69%) who tolerated treatment flow rates above 30 LPM. REM sleep time significantly increased with NFLOW use, however, other sleep stage times were not significantly altered. Obstructive apneas ceased in all but 2 of these patients with treatment. Four patients did not tolerate flow rates above 35 LPM and did not improve. We conclude that NFLOW treatment significantly decreases the number of oxyhemoglobin desaturations and improves oxyhemoglobin saturation in patients with OSA who tolerate the procedure.