N-acetylcysteine (NAC) decreases liver lactate levels in septic shock patients shown by magnetic resonance spectroscopy

Introduction

NAC was shown to improve the global oxygen consumption in sepsis and toxic liver failure. Very little is known about its effects on liver lactate levels under experimental conditions nothing to our knowledge in septic shock patients. The purpose of this study was to examine these effects using proton magnetic resonance spectroscopy (1H-MRS).

Methods

Nine patients with septic shock participated in this institutionally approved study (written informed consent by the relatives). 1H-MRS measurements were performed at 1.5 Tesla (Magnetom Vision Siemens) with a Steam sequence. A repetition time of 3000 ms and two different echo times of 135 and 270 ms were used to differentiate fatty acid signal from lactate signal. After the initial spectra, the patients received NAC (150 mg/kg bw). Forty-five minutes after this infusion a second measurement followed. Statistical analysis was performed by the Wilcoxon matched pairs signed rank sum-test.

Results

The median age was 66 (range: 37–90 years) and the median APACHE III score was 49 (range: 22–72). Following NAC infusion lactate levels showed a significant median decrease of 45% (range: 16-83%: P = 0.018). Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) did not change significantly within the first 24 h. The oxygenation index intermittently significantly increased (P = 0.0277) and then returned to baseline values within the first 24 h.

Conclusions

The decrease in liver lactate levels may demonstrate the improved liver blood flow and function after NAC application. However, the deterioration of the oxygenation index may limit NAC therapy in patients with an increased inspiratory oxygenation fraction.