Influence of dialysate temperature on creatinine peritoneal clearance in peritoneal dialysis patients: a randomized trial.

Introduction. It is common practice to encourage patients on continuous ambulatory peritoneal dialysis (PD) to warm dialysate to 37°C before peritoneal infusion; main international PD guidelines do not provide specific recommendation on this topic, and patients generally warm dialysate batches partially or do not warm them at all. Warming of dialysate is a time-consuming procedure, not free from potential risks (i.e. degradation of glucose), and should be justified by a clear clinical benefit. Methods. We designed a single blind randomized controlled trial where 18 stable PD patients were randomized to receive a peritoneal equilibration test either with dialysate at a controlled temperature of 37°C (intervention group) or with dialysate warmed with conventional methods (control group). Primary end-point was a higher peritoneal creatinine clearance in patients in the intervention group. Secondary end-points were: higher urea clearance, higher creatinine and urea mass transfer area coefficient (MTAC), lower abdominal discomfort in the intervention group, differences in blood pressure and body temperature between groups. Results. As expected, there was a statistically significant difference in dialysate temperature between the intervention and control group; other relevant patients' characteristics were not significantly different between groups. Patients in the intervention group did not show a significantly higher peritoneal creatinine clearance when compared to the control group (6.38 ± 0.52 ml/min vs 5.65 ± 0.37 ml/min, p=0.2682). Similar results were obtained for urea peritoneal clearance (8.28 ± 0.31 ml/min in the intervention group and 8.92 ± 0.45 ml/min in the control group, p=0.2561), MTAC creatinine (10.66 ± 1.77 ml/min in the intervention group and 8.82 ± 1.08 ml/min in the control group, p=0.3781) and MTAC urea (22.05 ± 1.69 ml/min in the intervention group and 22.66 ± 2.03 ml/min in the control group, p=0.8199). There were no significant differences in total abdominal discomfort questionnaire score, blood pressure and body temperature between the two groups. Conclusions. These relatively unexpected results could be related to the shortness of temperature effects on microcirculation and to the influence of factors other than blood flow transport in small solutes peritoneal clearances (i.e., the action of peritoneal interstitium). Using peritoneal dialysate at different temperatures without causing significant side effects or discomfort to patients appears feasible. We report a lack of benefit of warming peritoneal dialysate to 37°C; future PD guidelines should not reinforce this recommendation.