How CRRT Facilitates Nutritional Therapy Delivery
CRRT facilitates nutritional therapy delivery primarily through superior fluid balance control, which prevents intestinal edema, maintains gastrointestinal function, and allows administration of high-volume feeding formulas without volume overload concerns. 1, 2
Primary Mechanisms of Facilitation
Fluid Balance Management
- CRRT enables precise fluid removal that prevents intestinal edema and maintains proper gastrointestinal tract function, which is critical for enteral nutrition tolerance 2
- The continuous nature allows for strict control of fluid balance, creating "room" for nutritional formulas without causing volume overload 1, 2
- This is particularly valuable in hemodynamically unstable patients where intermittent hemodialysis would be poorly tolerated 1
Volume for Nutrition Delivery
- CRRT permits administration of high-volume feeding mixtures that would otherwise cause fluid overload in critically ill patients with acute kidney injury 2
- The Surviving Sepsis Campaign guidelines specifically recommend using CRRT to facilitate management of fluid balance in hemodynamically unstable septic patients 1
- This advantage is explicitly recognized in tumor lysis syndrome management, where CRRT is indicated for "facilitating the delivery of nutritional therapy" 1
Early Enteral Nutrition Introduction
- CRRT facilitates early introduction of nutrition via the enteral route by maintaining gastrointestinal function through fluid control 2
- The ESPEN guidelines on renal failure recommend providing nutrition preferentially via the enteral route in patients with acute kidney injury 1
- Recent expert recommendations emphasize that CRRT allows for better nutritional support compared to intermittent hemodialysis 1
Nutritional Considerations During CRRT
Increased Protein Requirements
- Protein requirements increase to 1.0-1.5 g/kg/day in patients on renal replacement therapy, and up to 1.7 g/kg/day in hypercatabolic patients on CRRT 1
- This increased requirement is due to amino acid losses of approximately 10-15 g/day in the effluent (0.2 g amino acids/L filtrate) 1
- Additional protein losses of 5-10 g/day occur depending on membrane material and therapy type 1
Energy Requirements
- Target total energy intake of 20-30 kcal/kg/day in patients with any stage of acute kidney injury 1
- More recent recommendations suggest 25-35 kcal/kg/day during CRRT 3
- Carbohydrates should account for 60-70% and lipids for 30-40% of calorie intake 3
Micronutrient Losses
- Water-soluble vitamins and trace elements require supplementation, as CRRT leads to significant losses in approximately 90% of patients within 5-7 days of initiation 1
- Electrolyte disturbances are common, including hypophosphatemia, hypomagnesemia, and hyponatremia 1
- The 2023 Critical Care guidelines recommend that adequate amounts of all essential trace elements and vitamins be supplied from the beginning of the CRRT period 1
Common Pitfalls and How to Avoid Them
Underestimating Nutrient Losses
- Do not use standard protein requirements; increase to at least 1.5 g/kg/day to account for CRRT-related losses 1, 3
- Monitor for micronutrient deficiencies after 5-7 days of CRRT and supplement accordingly 1
Fluid Restriction Errors
- Avoid restricting nutritional volume unnecessarily when CRRT is available, as this defeats one of its primary advantages 2
- Use CRRT's fluid removal capacity to enable adequate nutrition delivery rather than limiting feeding volumes 1
Glucose Management
- Avoid dialysate and replacement fluids with supraphysiologic glucose concentrations to prevent hyperglycemia 4, 5
- Be aware that citrate-based anticoagulation can provide additional calories that must be accounted for in the nutrition prescription 6