Hypertonic peritoneal equilibration test: Application to a peritoneal dialysis program

Peritoneal equilibration test (PET) employing a 2.27%/2.5% glucose exchange is the most widely used method of to evaluating peritoneal function and sm all solute transport. Hypertonic (3.86%/4.25% glucose) PET has been recentl y recommended for the evaluation of ultrafiltration and to study certain ca uses of ultrafiltration failure, such as aquaporin dysfunction, through the analysis of dialysate sodium. However, there is not enough information on the optimal way to express the changes in dialysate sodium concentration, t he normal range of values for this parameter, and possible adverse effects of hypertonic PET in the general population of peritoneal dialysis patients . A hypertonic PET was performed in 22 patients. Ultrafiltration failure (ult rafiltration <0.4 L) was present in seven patients. Patients with ultrafilt ration failure had higher small solute peritoneal transport and dialysate s odium concentration and had been treated with peritoneal dialysis for longe r periods of time. Dialysate sodium concentration at 60 and 240 minutes was directly correlated with small solute peritoneal transport calculated as D /PCr240 (r=0.74, p=0.0008 y r=0.84, p<0.0001) and inversely correlated with ultrafiltration (r=0.64, p=0.0016 y r=0.72, p=0.0002). An absence of a dip in dialyse sodium, suggestive of aquaporin dysfunction, was only observed in one patient with a high-average small solute peritoneal transport. Dialy sate sodium concentration at 60 minutes is a better discriminator between u ltrafiltration failure patients than parameters such as D/PNa or the absolu te dip in dialysate sodium with respect to time zero. We observed the follo wing adverse effects: symptomatic hypotension in 2 patients with preserved ultrafiltration. In conclusion, hypertonic PET allows to confirm the diagnosis of ultrafiltr ation failure, but monitoring dialysate sodium concentration offers additio nal information only in patients with severe aquaporin dysfunction. Hyperto nic PET may have adverse effects in patients without ultrafiltration failur e.