Nutritional and Metabolic Alterations during Continuous Renal Replacement Therapy

Abstract

Adequate feeding of critically ill patients under continuous renal replacement therapy (CRRT) remains a challenging issue. We performed a systematic search of the literature published between 1992 and 2012 using the quorum guidelines regarding nutrition in intensive care unit patients treated with CRRT. Daily recommended energy requirements during CRRT are between 25 and 35 kcal/kg with carbohydrates and lipids accounting for 60-70% and 30-40% of calorie intake, respectively. Daily protein needs range from 1.5 to 1.8 g/kg. Indirect calorimetry corrected for CRRT-induced CO₂ diversion should be used to more correctly match calorie intake to the real needs. This type of tool is not yet available but hopefully soon. Electrolyte deficit as well as overload have been described during CRRT but, in general, can be easily controlled. Although not strongly evidenced, consensus exists to supplement important micronutrients such as amino acids (glutamine), water-soluble vitamins and trace elements.

Practical issues of nutrition during continuous renal replacement therapy

“…The incidence of hypokalaemia in patients undergoing renal replacement therapy is 5-25% [3]. The condition is most commonly caused by the use of fluids low in potassium for correction of hyperkalaemia.…”

“…The incidence of hypophosphataemia during CRRT is high and ranges from 10.9 to 65% [3]. Once the fluids containing physiological concentrations of phosphates have been introduced, its incidence substantially decreases.…”

“…3] has not shown significant differences between the techniques based on diffusion and convection. At present, there are no data concerning the effects of filters of higher adsorptive capacity or the high cut-off point on the loss of nutrients during CRRT procedures [3,4].…”

“…3] has not shown significant differences between the techniques based on diffusion and convection. At present, there are no data concerning the effects of filters of higher adsorptive capacity or the high cut-off point on the loss of nutrients during CRRT procedures [3,4].The above findings clearly reveal that since the CRRT procedure significantly affects the supply of nutrients in critically ill patients, this kind of therapy should be considered in terms of energy-protein requirements. …”

“…In critically ill patients undergoing CRRT procedures, an increase in protein supply should be considered during nutritional interventions; firstly, due to increased loss with the ultrafiltrate; secondly, because an increase in protein supply to values exceeding 1.5 g kg IBW -1 day -1 , can have beneficial effects on prognosis. The current ESPEN guidelines recommend protein supply in a dose of 1.5 g kg IBW -1 day -1 in critically ill patients during intensified metabolism; when CRRT is introduced, this dose should be increased by 0.2 g kg IBW -1 day -1 [3]. The 2016 ASPEN guidelines recommend the daily supply of proteins in critically ill patients in the amount of 2 g kg -1 bw -2 .…”