Nutritional status in hypercatabolic patients with acute renal failure

Introduction

In spite of optimized artificial nutrition, the development of malnutrition is often rapid in critically ill patients with acute renal failure undergoing a continuous venovenous hemofiltration (CVVH) [1].

Methods

In this prospective-observational study we evaluated all patients with hypercatabolic status during a period of 15 days. A Hospal Prisma blood pump at a ultrafiltrate rate of 1.2 l/h and polyacrylonitrile AN69HF hemofilters were employed. Daily caloric support and nitrogen intake as well as urinary nitrogen loss were recorded. Specimens of ultrafiltrate (200 ml) were collected every 48 hours from a 5 l pool ultrafiltrate. Daily nitrogen losses were calculated by multiplying the nitrogen concentration measured in each specimen by the total amount of ultrafiltrate produced over a 24-hour period and by adding to this the standard estimate for insensible nitrogen losses (15 mg/kg/day). Nitrogen balance was estimated as the difference between intake and losses after taking changes in total urea body pool into account. The evaluation of nutritional status was assessed collecting lost body weight everyday and lymphocyte count, serum albumin, serum pre-albumin, transferrin, at least twice a week. Comparison of nutritional parameters between the beginning of the treatment and after 15 days was made using Student's t-test (P < 0.05).

Results

Twelve critically ill patients (four burnt and eight septic) were studied. Their mean SAPS II was 48.6 ± 15.5 and the mean of SOFA was 11.1 ± 3.1. They received a mean amount of 43.4 kcal/kg/day. The protein intake was of 1.8 g/kg/day, in spite of fact that more aggressive renal replacement therapy was used to achieve adequate control of uremia (mean plasma urea 15.4 ± 7.2 mM/l). The mean nitrogen losses in the ultrafiltrate were 25.4 ± 5.4 g/day and the nitrogen balance was -9.8 ± 0.3 g/day. During the period of study the lost body weight was 0.53 ± 0.1 kg/day. The nutritional parameters measured (beginning vs 15 th day) are shown in the Table.

Table 1

Conclusion

Hypercaloric and hyperprotein diet, considering standard nutritional protocols, does not assure adequate nutritional status in hypercatabolic patients with acute renal failure undergoing renal replacement therapy. Increase in lymphocyte count could be correlated with improvement of septic condition.