A Prospective Comparative Study of Moderate Versus High Protein Intake for Critically Ill Patients with Acute Renal Failure

Abstract

Critically ill patients with acute renal failure are traditionally treated with low-protein diets to help control uremia. This dietary approach may be deleterious to the patient's nutritional status and unnecessary, especially if continuous renal placement therapies (CRRT) are used. However, the optimal amount of protein supplementation during CRRT is unknown. In patients receiving CRRT, a high protein intake may result in a positive nitrogen balance in the absence of uncontrolled uremia. Accordingly, we studied nitrogen metabolism in two consecutive cohorts of acute renal failure patients receiving equal amounts of calories but variable amounts of nitrogen. One group received protein according to the preferences of the attending clinician, the other a high and fixed amount of protein (2.5 g/kg/day). Patients treated according to attending clinician preferences received significantly less dietary protein (1.2 g/kg/day vs. 2.5 g/kg/day; p < 0.0001) and had a negative mean nitrogen balance of -5.5 g/day. Patients receiving a high and fixed amount of protein had a less negative mean nitrogen balance (-1.92 g/day). Such patients were more likely to experience a positive nitrogen balance during any 24-h period (53.6% vs. 36.7%; p < 0.05). They also required more aggressive hemofiltration to maintain control of uremia (mean ultradiafiltrate volume: 2145 mL/h vs. 1658 mL/h; p < 0.0001) and had a significantly higher but still acceptable mean plasma urea level (26.6 mmol/L vs. 18 mmol/L; p < 0.0001). Survival was not significantly different in the two groups (37.5% vs. 31.3%). We conclude that a high-protein diet can be safely administered to critically ill patients with acute renal failure receiving continuous renal replacement therapy. Such a high protein intake improves nitrogen balance when compared to moderate protein intake. A low protein intake is unnecessary in patients treated with CRRT.

Continuous renal replacement therapy in the critically ill patient

“…These features permit a high protein and caloric load to compensate for the catabolic state in acute renal failure. However, studies by Bellomo et al [81] have shown that if you go up to 2.0 g/kg or 2.5 g/kg of protein loading, a positive nitrogen balance cannot be achieved and there is no additional nutritional benefit. Thus, even though CRRT permits unlimited nutritional support, there is no advantage in "overfeeding" patients.…”

Daily Protein Intake and Patient Outcomes in Severe Acute Kidney Injury: Findings of the Randomized Evaluation of Normal versus Augmented Level of Replacement Therapy (RENAL) Trial

“…Moreover, although such recommendations appear reasonable from a nitrogen-balance point of view, especially given the loss of amino acids during CRRT [21,22,23,24,25,26,27], the only randomized controlled trial focusing on clinical outcomes was conducted in 1973 [28] and has little relevance to modern practice. Moreover, recent investigations have suggested that permissive underfeeding, trophic feeding, or delayed parenteral feeding may be equivalent or perhaps superior to currently recommended approaches [29,30,31,32].…”

Diagnosis and Treatment of Acute Tubular Necrosis

“…Feinstein and colleagues (92) could not show a difference in a double-blind study that randomly assigned 30 patients with ATN to one of three isocaloric regimens: glucose alone, glucose plus essential amino acids, or glucose plus essential and nonessential amino acids. Because of the catabolic state of ATN and associated comorbid illness, a positive nitrogen balance is difficult to achieve in these patients (93,94). A recent review has recommended providing protein and nonprotein calories to meet calculated energy expenditures at a rate not to exceed 1.5 g of protein intake per kg of body weight per day in patients with ATN (95).…”