Autonomic function in patients on continuous ambulatory peritoneal dialysis

OBJECTIVE: To investigate sympathetic function in the peripheries of patients on chronic ambulatory peritoneal dialysis (CAPD) using noninvasive techniques. DESIGN: Comparison of peripheral blood flow responses in sympathetic vasoconstrictor reflexes in CAPD patients and matched control subjects. SETTING: Tertiary care hospital and research institution. PATIENTS: Twenty-three clinically stable CAPD patients and 23 control subjects matched for age, sex, and drug therapy. MAIN OUTCOME MEASURES: Sympathetic activity assessed from the reductions in hand and foot blood flow induced by a deep breath and by body surface cooling. Cardiac autonomic activity measured by the changes in heart rate produced by deep breathing, a Valsalva maneuver, and standing from lying. RESULTS: A deep breath induced mean decreases in hand blood flow of 65.1% in the patients and 82.8% in their matched controls. Corresponding reductions in the foot were 46.0% and 70.0%. Body surface cooling reduced mean hand blood flow by 50.3% in the patients and 71.8% in the control subjects. Corresponding values in the foot were 26.7% and 43.6%. The differences in response between the patients and their matched control subjects were all significant (p < 0.01). Cardiac autonomic function assessed by standard tests of heart rate variability was significantly impaired in the patients compared with the control subjects in two of the three tests used (p < 0.001). CONCLUSIONS: Cardiovascular autonomic impairment can affect the peripheral circulation as well as the heart in patients on dialysis, and this may have implications for cardiovascular homeostasis.