Improvement of sleep apnea in patients with chronic renal failure who undergo nocturnal hemodialysis

Background: Sleep apnea is common in patients with chronic renal failure an d is not improved by either conventional hemodialysis or peritoneal dialysi s. With nocturnal hemodialysis, patients undergo hemodialysis seven nights per week at home, while sleeping. We hypothesized that nocturnal hemodialys is would correct sleep apnea in patients with chronic renal failure because of its greater effectiveness. Methods: Fourteen patients who were undergoing conventional hemodialysis fo r four hours on each of three days per week underwent overnight polysomnogr aphy. The patients were then switched to nocturnal hemodialysis for eight h ours during each of six or seven nights a week. They underwent polysomnogra phy again 6 to 15 months later on one night when they were undergoing noctu rnal hemodialysis and on another night when they were not. Results: The mean (+/-SD) serum creatinine concentration was significantly lower during the period when the patients were undergoing nocturnal hemodia lysis than during the period when they were undergoing conventional hemodia lysis (3.9+/-1.1 vs. 12.8+/-3.2 mg per deciliter [342+/-101 vs. 1131+/-287 micromol per liter], P<0.001). The conversion from conventional hemodialysi s to nocturnal hemodialysis was associated with a reduction in the frequenc y of apnea and hypopnea from 25+/-25 to 8+/-8 episodes per hour of sleep (P =0.03). This reduction occurred predominantly in seven patients with sleep apnea, in whom the frequency of episodes fell from 46+/-19 to 9+/-9 per hou r (P=0.006), accompanied by increases in the minimal oxygen saturation (fro m 89.2+/-1.8 to 94.1+/-1.6 percent, P=0.005), transcutaneous partial pressu re of carbon dioxide (from 38.5+/-4.3 to 48.3+/-4.9 mm Hg, P=0.006), and se rum bicarbonate concentration (from 23.2+/-1.8 to 27.8+/-0.8 mmol per liter , P<0.001). During the period when these seven patients were undergoing noc turnal hemodialysis, the apnea-hypopnea index measured on nights when they were not undergoing nocturnal hemodialysis was greater than that on nights when they were undergoing nocturnal hemodialysis, but it still remained low er than it had been during the period when they were undergoing conventiona l hemodialysis (P=0.05). Conclusions: Nocturnal hemodialysis corrects sleep apnea associated with ch ronic renal failure. (N Engl J Med 2001;344:102-7.) Copyright (C) 2001 Mass achusetts Medical Society.