Left ventricular hypertrophy and nocturnal hypoxemia in hemodialysis patients.

Objective Nocturnal hypoxemia has recently been proposed as a cardiovascular risk factor in patients with chronic renal failure. In this study we have tested the hypothesis that this disturbance is associated with left ventricular hypertrophy (LVH) in dialysis patients. Methods During a mid-week non-dialysis day, 38 hemodialysis patients underwent continuous monitoring of arterial O 2 saturation (SaO 2 ) during night-time as well as 24 h ambulatory blood pressure monitoring and echocardiography. Results Eighteen patients had one or more episodes of O 2 desaturation during night-time (average: 21 episodes; range 1 to 120) while the other 20 had no episode. Neither day-time arterial pressure nor heart rate were significantly associated with nocturnal hypoxemia. However there was a significant correlation between the night/day systolic ratio and the severity of hypoxemia during night-time (r = 0.36, P = 0.03). On multivariate analysis, nocturnal hypoxemia proved to be the stronger independent predictor of relative wall thickness, mean wall thickness and left ventricular mass index, suggesting that nocturnal O 2 desaturation is linked to concentric hypertrophy and to concentric geometry of the left ventricle. Accordingly, the proportion of patients with such geometric alteration was higher (X 2 = 4.1, P = 0.04) in patients with a pulse oximetry severity score > 50 th percentile [15 of 19 (79%)] than in those below this threshold [nine of 19 (47%)]. Conclusions Nocturnal hypoxemia is an important correlate of LVH in hemodialysis patients. Such an association is largely independent of arterial pressure. These data further underscore the importance of disturbed respiratory control as a cardiovascular risk factor in dialysis patients.