EFFECT OF AUTONOMIC NEUROPATHY ON VENTILATORY RESPONSE TO PROGRESSIVEHYPERCAPNIA IN DIALYSIS PATIENTS

The impact of autonomic neuropathy (common in patients on haemodialysi s) on ventilatory response to hypercapnia has been studied. We investi gated cardiac reflex tests in 20 patients on chronic haemodialysis (8 patients were found with and 12 without neuropathy of the autonomic ne rvous system). Using the hyperoxic CO2-rebreathing method (according t o Read), we tested the above-mentioned two groups of patients and comp ared them with 14 healthy control subjects. Accumulation of CO2 in blo od with hyperoxic CO2 rebreathing stimulates central chemoreceptors, a nd therefore causes a progressive rise in minute ventilation. In patie nts with autonomic neuropathy (n = 8), ventilatory response to increas ing pCO(2) was significantly lower than that in the controls (1.7+/-0. 3 versus 3.2 +/- 0.51/min/mmHg, P< 0.001). On the other hand ventilato ry response in patients without autonomic damage (n = 12) showed no si gnificant difference when compared to controls (3.1 +/- 0.81/min/mmHg) . There were no differences in lung function, arterial blood gas analy sis, blood chemistry, duration on dialysis, and demographic data when comparing the patients with and those without autonomic damage. Our an alysis shows different patterns of ventilatory response to increasing pCO(2) in patients on haemodialysis. Autonomic neuropathy has to be co nsidered when rebreathing tests are interpreted. The clinical relevanc e of these findings needs further investigation.