Continuous L-arginine infusion does not deteriorate the haemodynamic condition in patients with severe sepsis

Introduction

Septic patients have reduced plasma arginine (ARG) levels, and have been considered ARG deficient. This has resulted in the use of ARG-enriched enteral formulas, which recently raised much concern. These formulas, however, also contain other components besides ARG. ARG is the precursor for nitric oxide, a known vasodilator. Since little is known about the haemodynamic effects of continuous i.v. ARG supplementation as a single component in sepsis, we aimed to study dose-response effects of ARG in severe septic patients.

Methods

Eight ICU patients with severe sepsis/septic shock (<48 hours) were included. APACHE II scores ranged between 27 and 43. Norepinephrine dose ranged between 0.05 and 0.8 μg/kg/min. After 2 hours baseline, L-ARG-HCl was infused continuously in three stepwise increased doses (0.6, 1.2 and 1.8 μmol/kg/min), each dose for 2 hours. Haemodynamics were recorded at 30-min intervals. Plasma arginine levels were analysed by HPLC. Repeated-measurements ANOVA was used to compare doses; data are means ± SEM.

Results

No significant changes in systemic blood pressure were observed. Compared with plasma ARG levels of age-matched healthy subjects (81 ± 5 μM), levels were reduced in our patients (P < 0.05). The heart rate decreased during ARG supplementation and the stroke volume increased (Table 1).

Table 1

Conclusion

ARG infusion does not affect systemic and pulmonary blood pressure, but increases the cardiac stroke volume. This indicates that continuous ARG supplementation does not deteriorate the haemodynamic condition in severe septic patients, despite its vasodilating effect.