RESUMEN
ANTECEDENTS: Arterial pressure is negatively associated to pain perception. OBJECTIVES: In this study, pain and the relations between arterial pressure and pain threshold were compared at the beginning and end of the haemodialysis. METHODS: 14 patients with chronic renal disease participated in the study. Pain thresholds were evaluated with pressure algometry bilaterally at two tender points: the second rib and the knee. Arterial pressure and pain thresholds were assessed twice: 1) 15 min alter dialysis onset and 2) 30 min before dialysis ended. RESULTS: Arterial pressure remains unchanged through the dialysis. The course of dialysis was associated to a decrease in pain threshold in the second left rib and left and right knees. At the beginning of dialysis arterial pressure were uncorrelated with pain, while at the end of the dialysis both systolic and diastolic arterial pressure were strongly associated to pain thresholds (rs between 0.552 and 0.806): increased arterial pressure was associated to lower pain in terms of increased threshold. CONCLUSIONS: Haemodialysis is associated to changes in pain sensitivity and in the relationships between arterial pressure and pain, suggesting a modification in the ascending pain inhibition system arising from the cardiovascular system. Possible explanations of this effect include the changes produced by haemodialysis in cognitive-perceptive functions, in autonomic cardiovascular regulation, and in the habituation of stress-related variables.