Nutritional management of acute kidney injury in the critically ill: a focus on enteral feeding

Abstract

Optimal nutritional management of critically ill patients who present with acute kidney injury (AKI) is paramount. The management of this patient population is probably more complicated than that of chronic care haemodialysis (HD) patients as AKI patients have significant protein catabolism, insulin resistance (abnormal carbohydrate metabolism) and an altered fat metabolism, and AKI patients on continuous renal replacement therapy (RRT) are at greater risk of protein and micronutrient losses. The primary goals of nutritional management of AKI patients are to attenuate protein (muscle) catabolism, and to replace micronutrient losses, specifically folic acid, thiamine and selenium, while being mindful of the potentially harmful effects of excessive vitamin C and vitamin A in retinol form. Hence, it is prudent, if standard enteral feeds are used, that the latter are considered, especially if the patient is on RRT. The majority of intensive care units (ICUs) in South Africa do not have scale beds or Bluetooth bed scales to accurately measure body weight, which is required to accurately determine fluid and nitrogen balance. Nitrogen balance is required for the calculation of the appropriate prescription of protein. Hence, critically ill AKI patients on RRT are at possible risk of the provision of either insufficient or excessive protein. Insufficient protein intake in catabolic AKI patients is associated with an increased mortality risk. A good understanding of the classification of patients with AKI, the types of RRT used in the management of these patients, the specialised macronutrient and micronutrient requirements, and appropriate fluid management is required for the appropriate dietary management of critically ill AKI patients. The aim of this review is to address all of these. To achieve optimal nutritional management of AKI patients in the ICU, especially those on RRT in South Africa, it is critically important that the lack of ICU scale beds and ready-to-hang specialised dialysis enteral feeds is addressed.