N-acetylcysteine improves indocyanine green extraction and oxygen transport during hepatic dysfunction

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Abstract
To investigate whether the beneficial systemic hemodynamic effects of N-acetylcysteine, an agent that increases cyclic guanosine monophosphate (cGMP) concentration in fulminant hepatic failure, are present in a range of liver disorders and what concurrent effect this agent has on the hepatic-splanchnic circulation. Liver Failure Unit, King's College Hospital, London, UK. Fifteen patients with hepatic dysfunction who were mechanically ventilated, either after liver transplantation or during an acute or decompensated chronic liver disorder. Prostacyclin was administered at a continuous infusion rate of 5 ng/kg/min for 60 mins. After a washout period, the hemodynamic effects of this infusion were compared with the effects present during infusion of N-acetylcysteine at 150 mg/kg in 250 mL of 5% dextrose in water over 15 mins and then 50 mg/kg in 250 mL of 5% dextrose for 45 mins at an infusion rate of 62.5 mL/hr. Following N-acetylcysteine infusion, the baseline oxygen delivery (DO2) increased from 667 +/- 154 to 751 +/- 166 (SD) mL/min/m sup 2, and oxygen consumption (VO2) improved in 13 of 15 patients (150 +/- 30 to 169 +/- 25 mL/min/m2) (p 10% from baseline [n = 6; 40%]) had a significantly lower baseline consumption compared with that of nonresponders (133 vs. 162 mL/min/m2, p = .04). No clear relationship between the increments in VO2 and indocyanine green clearance was observed (r2 = .21; p = .08). Prostacyclin resulted in moderate improvements in systemic DO2 (but not VO2) and a nonsignificant increase in indocyanine green clearance. N-acetylcysteine increases systemic VO2 in a proportion of patients with a wide variety of hepatic disorders. In addition, N-acetylcysteine elicits an improvement in indocyanine green clearance. These properties may be clinically useful in a range of critical illnesses where systemic or hepatic-splanchnic circulations are compromised. (Crit Care Med 1997; 25:236-242)