Increase in antioxidant capacity of plasma during propofol anesthesia

We have examined the effect of total intravenous anesthesia (TIVA) using a continuous propofol infusion on the antioxidant capacity of plasma in 18 neurosurgical patients who required cerebrospinal fluid shunting. Patients were premedicated with hydroxyzine, alprazolam, and atropine. Anesthesia was induced intravenously with propofol 1.5 mg kg-1 and sufentanil 0.15-0.3 microgram kg-1. Tracheal intubation was facilitated with atracurium 0.5 mg kg-1. Anesthesia was maintained with a continuous propofol infusion at an increasing rate from 6 to 12 mg kg-1 h-1 under controlled ventilation (FiO2 = 0.4 in air). In all patients, arterial blood samples were drawn before induction of anesthesia and during surgery for measurement of blood propofol concentration and plasma antioxidant capacity, which was assessed as the ability to inhibit lipid peroxidation. Lipid peroxidation was induced in vitro by exposing a linoleic acid microemulsion to hemoglobin-generated oxoferryl radicals, and assessed by ultraweak chemiluminescence in the absence (control) and the presence of the plasma samples. The antioxidant capacity of plasma, measured by the inhibition of light emission and expressed as a percentage of control, increased significantly from 39.8 +/- 2% (mean +/- SEM) to 44.7 +/- 2.4% during anesthesia (Wilcoxon test, p < 0.001). No correlation was observed between this increased resistance to lipid peroxidation and blood propofol concentrations (Spearman test, r = 0.07, NS). We conclude that the capacity of plasma to inhibit lipid peroxidation increases in patients during TIVA maintained with a continuous propofol infusion.