Effect of Ultrafiltration on Sleep Apnea and Cardiac Function in End-Stage Renal Disease

Abstract

Rationale: End-stage renal disease (ESRD) patients have high annual mortality mainly due to cardiovascular causes. The acute effects of obstructive and central sleep apnea on cardiac function in ESRD patients have not been determined. We therefore tested, in patients with ESRD, the hypotheses that (1) sleep apnea induces deterioration in cardiac function overnight and (2) attenuation of sleep apnea severity by ultrafiltration (UF) attenuates this deterioration. Methods: At baseline, ESRD patients, on conventional hemodialysis, with left ventricular ejection fraction (LVEF) >45% had polysomnography (PSG) performed on a non-dialysis day to determine the apnea-hypopnea index (AHI). Echocardiography was performed at the bedside, before and after sleep. Isovolumetric contraction time divided by left ventricular ejection time (IVCT/ET) and isovolumetric relaxation time divided by ET (IVRT/ET) were measured by tissue doppler imaging. The myocardial performance index (MPI), a composite of systolic and diastolic function was also calculated. One week later, subjects with sleep apnea (AHI ≥15) had fluid removed by UF, followed by repeat PSG and echocardiography. ­Results: Fifteen subjects had baseline measurements, of which 7 had an AHI <15 (no–sleep-apnea group) and 8 had an AHI ≥15 (sleep-apnea group). At baseline, there was no overnight change in the LVEF in either the no-sleep-apnea group or the sleep-apnea group. In the no-sleep-apnea group, there was also no overnight change in MPI, IVCT/ET and IVRT/ET. However, in the sleep-apnea group there were overnight increases in MPI, IVCT/ET and IVRT/ET (p = 0.008, 0.007 and 0.031, respectively), indicating deterioration in systolic and diastolic function. Following fluid removal by UF in the sleep-apnea group, the AHI decreased by 48.7% (p = 0.012) and overnight increases in MPI, IVCT/ET and IVRT/ET observed at baseline were abolished. Conclusions: In ESRD, cardiac function deteriorates overnight in those with sleep apnea, but not in those without sleep apnea. This overnight deterioration in the sleep-apnea group may be at least partially due to sleep apnea, since attenuation of sleep apnea by UF was accompanied by elimination of this deleterious overnight effect.