Cooler Dialysis and Liver Perfusion and Function

Having hemodialysis affects the blood supply to various organs in the body including the heart and the brain. With time, these effects build up and can affect the way these organs function. The investigators have previously shown that the liver (a key organ which works to help clean the blood, make proteins and turn all your food into energy) is also affected. One of the ways to help protect organs from injury due to dialysis has been cooling during dialysis. The investigators want to examine whether cooling during dialysis protects the blood supply to the liver. CT imaging will be used to measure this blood supply during hemodialysis with standard and cooler settings.

Hemodialysis exerts significant hemodynamic effects with widespread consequences on vulnerable vascular beds. Cardiac injury, including myocardial stunning and subclinical myocardial ischemia, appears to be common and associated with significantly increased mortality. The liver has been shown to have preserved blood flow due to its dual blood supply. Even so, the liver excretory function is decreased and endotoxin levels in the blood increase during hemodialysis. Extracorporeal cooling during dialysis has been associated with protective effects on the brain and heart of dialysis patients. The effects of cooler dialysis on liver perfusion, function and endotoxemia during hemodialysis is unknown. The investigators therefore propose to use CT perfusion imaging to examine the effect of cooling during hemodialysis on liver perfusion, relating this effect to endotoxin translocation and myocardial dysfunction. Additionally, they intend to investigate the potential effects on hepatic function in this context, examining the relationship between liver perfusion and endotoxemia, the metabolism of uremic toxins and clinical symptoms of uremia. This is a prospective randomized cross-over study involving a single center recruiting patients from the prevalent dialysis population of London Health Sciences Centre (LHSC) Renal Program. Once recruited, patients will undergo two study hemodialysis sessions - one will use standard dialysate temperature of 36.5 degrees Celsius (HD36.5) and one will use cooler dialysate temperature at 35 degrees Celsius (HD35). The order of these two sessions will be randomly allocated. Before, during and after each session, participants will undergo cardiac and hepatic assessment. This will include CT scans, 2D echocardiography and indocyanine green (ICG) clearance measurements. In addition, participants will answer a number of questionnaires about uremic symptoms and blood tests will also be done. The investigators' aim is to characterize and compare liver function and perfusion before during and after hemodialysis, with standard and cooler dialysate temperature.