Hepatic O₂ transport and energy balance in hyperdynamic porcine endotoxin shock: N^G-monornethyl-L-arginine (L-NMMA) versus noradrenaline

Introduction

Nitric oxide synthase (NOS) inhibition is currently investigated as a treatment of arterial hypotension associated with septic shock, but controversial data are available with respect to hepatic O₂ balance. Therefore we studied the effect of NOS inhibition with L-NMMA on liver O₂ transport as well as energy balance, in comparison to a standard treatment with noradrenaline (NOR) in a hyperdynamic endotoxin (ETX) shock model.

Methods

Thirty anesthetized pigs were randomly assigned to 3 groups 12 h after induction of endotoxic shock with continuous LPS infusion: ETX group: no drug therapy (n = 8); NOR group (n = 11) and L-NMMA group (n = 11): vasopressor therapy with NOR and L-NMMA was titrated to maintain MAP at preshock levels. Hepatic blood flow (Transonic^® Doppler ultrasound), O₂ kinetics as well as mean and frequency distribution of intracapillary HbO₂ saturation (remission spectrophotometry, EMPHO) were measured.

Results

Data are median and interquartile range. *P < 0.05 vs preshock (RM ANOVA on ranks). **P < 0.05 between groups (ANOVA).

Conclusions

Although, in contrast to NOR, L-NMMA did notfurther increase macrocirculatory liver O₂ availability, there was no difference between the two treatments with regard to microcircula-tory O₂ supply and O₂ uptake. Hence, neither of the two treatments improved liver energy balance.

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