Enhancing Dialysis Adequacy: Effects of Intradialytic Exercise

For patients with severe chronic kidney disease, regular dialysis to remove toxins and waste products from the blood is essential to maintain life. The adequacy of dialysis is quantified by the removal of these toxic solutes and is an important parameter in the assessment of the therapy. Previous efforts to enhance urea clearance have centered around factors such as increasing dialysis dose by increasing dialysis time or carrying out more frequent dialysis sessions. However this concept is confronted with the barriers of patient compliance and cost implications. Many patients are resilient to increasing their dialysis time, presenting a major challenge for enhancing the efficacy of dialysis therapy. Therefore, alternative methods of improving dialysis adequacy, with interventions aimed at enhancing solute clearance, are highly warranted. One such intervention could be exercising during haemodialysis (HD). 85% of the body is comprised of lean tissue, of which 73% is water. As many toxic solutes are water based, large amounts will be stored in the muscle. When sitting at rest during HD the blood flow to the muscles is four times less compared to the major organs. Additionally, the HD process causes blood vessels to constrict, further restricting blood flow to the muscle. Consequently there is insufficient blood flow to remove the toxins stored in the muscle. By exercising during dialysis, blood flow to the muscle is increased to sustain the demand for oxygen and energy, thereby allowing toxic solutes to be removed and cleared through the dialysis machine. Therefore the aim of this study is to implement an efficient exercise intervention during dialysis and determine its effects on dialysis adequacy in comparison to the traditional prescription of increased dialysis time. In particular, the study aims to explore the acute effects of exercise during dialysis on the removal of several established uremic toxins.