Glutamine serum, adherence and losses in continuous renal replacement therapies in critically ill patients

Introduction

Continuous renal replacement therapies (CRRT) readily allow for the nutritional support of these high catabolic states, but also contribute to the nitrogen loss through filtration of free amino acids and small peptides across the hemofilters. Amino acid clearances and calculated losses in adults on continuous venovenous hemofiltration (CVVHD) have been reported in the range of 2–11% of dietary intake. Glutamine is an very important amino acid in critically ill patients.

Objective

To analyse glutamine serum, losses and adherence from CRRT treatments in critically ill patients.

Materials and methods

Paired samples from serum, venous and dialysate/ultrafiltrate were obtained during CRRT procedures from 41 patients in a 27-bed ICU from July 2002 to May 2003. Paired samples were collected from 1, 6, 12, 24, 36 and 48 hours of continuous hemodialysis, a total of six samples of serum, venous and dialysate. PAN 650 filters were used in all patients. The blood flows was 150 ml/min in all patients and the dialysate flow during CVVHD was 16.6 ml/min. Amino acid assays, using high-pressure liquid chromatography serum, venous and dialysate, were performed by laboratory CTN and Pardini.

Results

The average patient age was 73.08 years (43–88 years) and the APACHE II score was 18.37 (11–28). Serum, venous and dialysate amino acids were obtained in 41 patients and glutamine was analysed (μmol/l). Analyses were performed on the average of amino acids. Statistical calculations were made by analysis of variance, linear, nonlinear and logarithmic regression.

Conclusion

Glutamine is very important in critically ill patients. Glutamine was demonstrated to be decreased, probably, as an essential amino acid in sepsis or catabolic patients, greatly consumed. We should not estimate the protein necessity in a septic or trauma patient on CHVVD based exclusively on the amino acid loss. Other factors, such as the adsorption of amino acids, may contribute to the continuous catabolism seen in these critically ill patients.