Assessment of the symptomatic benefit of cool dialysate

Symptoms were evaluated in 13 haemodialysis patients at dialysate temperatures between 37 and 35 degrees C. After a control period at 37 degrees C (stage 1) dialysate flow rate was increased from 300 ml/min in half the patients but no change in temperature was made (stage 2). In stage 3 dialysate temperature was reduced to 36.5 degrees C and in stage 4 to 35 degrees C. Blood pressure and temperature were measured pre- and post dialysis and patient completed a questionnaire indicating if they experienced any of nine specified symptoms: itch, restless legs, nausea, vomiting, headache, cramp, lethargy, hypotension and change in temperature. Trial stages were compared with chi 2 analysis using Yates correction. Symptoms per dialysis fell from 1.11 to 0.71 between stage 1 and 2 (p less than 0.0005). This was considered to be a trial effect. There was no further significant improvement in symptoms overall as the temperature was reduced to 35 degrees C. However, if complaints of coldness are excluded, there was a progressive reduction in symptoms from stage 1 to stage 4. Dialysate flow rate did not affect symptom reporting. There was no effect on body core temperature or blood pressure due to cool dialysate. Our results suggest there may be some benefit in lowering the dialysate temperature but this is small in relation to the placebo effect. Caution must be used in assessing similar studies using small numbers of dialyses.