Predialytic versus intradialytic nutrition: Tolerability and effects on solute removal during hemodialysis

Nutritionalmanagement of patients with endstage renal disease is a challenging exercisefor nephrologists, nutritionists and dialysis nurses, with a high unmet needfor improving caloric and protein requirements, whilst balancing the inevitableincrease in sodium, potassium and phosphorus intakes which accompaniesnutrition supplementation.1 While it is common for nephrologists toprescribe protein supplements, compliance to these at prescribed doses isrelatively low. Many dialysis patients in India are still unable to meet thehigh protein requirement and therefore, suffer from protein-energy wasting. Inthe light of the recent studies on feeding during hemodialysis which encourageintradialytic meal intake, and also an observation of regular intradialyticeating in several of our patients on hemodialysis, we designed this study todetermine the optimal timing of oral nutrition supplementation.2.3 Hemodialysisis a catabolic state with substantial protein losses, depending on thetechnique and membrane parameters. Therefore, provision of directly observedhigh protein meal during hemodialysis or before it, can be beneficial inmitigating the muscle-wasting induced by hemodialysis.

Briefreview:

Apoint of contention is the timing of oral nutrition supplements. Few studiesdone previously, have highlighted higher incidence of hypotensive episodes inthose patients eating during hemodialysis, which is explained by splanchnicvasodilatation and fall in systemic vascular resistance.4,5 However,the effect of eating on hemodynamics during hemodialysis is inconsistent. Thepresent study will also evaluate frequency of hypotensive episodes and thegeneral tolerability of the hemodialysis when the patient has eaten. Anothercause for concern is the observation of decreased dialysis efficacy as measuredby Kt/V when intradialytic oral nutrition is provided.6,7 The fallin Kt/V in these studies is minimal and unlikely to cause clinical effects. Also,it is unclear from previous studies, whether urea is the only solute whoseremoval is affected by eating a high protein meal during dialysis, or does theeffect extend to potassium and phosphorus removal as well. The present studywill measure changes in serum levels of urea, potassium and phosphorus and alsodirectly assess dialysate removal of these nutrients. By measuring dialysateremoval of solutes, it can determine the safety of eating during hemodialysis,for patients with higher baseline urea, potassium and phosphorus.

Allowingfor eating during hemodialysis is a policy matter which varies from unit tounit, and previous surveys conducted in the United States revealed that asubstantial proportion of nephrologists support intradialytic eating.8Certain practical aspects govern our institute’s policy for allowing eatingduring dialysis. First, many patients come from far-flung areas and may notfind the time to prepare and consume a meal prior to coming for a dialysissession. Second, patients commonly report hunger after starting dialysis whichcan be mitigated by eating during dialysis. Ensuring consumption of a highcalorie and high protein meal in a directly observed manner has previouslyshown improvement in nutritional parameters. 9