The role of sympathetic dysfunction in blood pressure regulation in uremic patients treated by continuous ambulatory peritoneal dialysis.

The role of autonomic nervous system dysfunction in the regulation of arterial blood pressure in 4 male and 10 female uremic patients, age 35-65 years (57 +/- 9 years), treated by continuous ambulatory peritoneal dialysis (CAPD) for 6-40 months (20 +/- 12 months), was studied. The integrity of the entire autonomic reflex arc was checked using Valsalva's test and the orthostasis challenge test. In parallel, efferent sympathetic function was tested with the handgrip test. A significantly decreased Valsalva ratio was found in 7 patients (50%), and it was normal in only 2 patients (14%). The handgrip test was subnormal in 5 patients (36%) and abnormal in 7 patients (50%). On the contrary, the orthostatic challenge test showed normal compensatory reaction in 10 patients (72%). The evaluation of three autonomic tests showed combined (afferent + efferent) lesion in 6 patients (43%), predominant afferent lesion in 3 patients (21%), and in 3 patients predominant efferent lesion. In 2 patients (14%) there was no end-organ response. Despite significant autonomic nervous system dysfunction in uremics on CAPD, as demonstrated by these results, blood pressure regulation in the supine and upright position was adequate in most patients (72%), indicating a relatively greater role of other blood pressure-regulating factors.