Immune-enhancing effect of arginine on patients with severe traumatic brain injuries who have undergone therapeutic brain hypothermia

The immune-enhancing effect of arginine was evaluated in 32 traumatic brain injured patients who had undergone therapeutic brain hypothermia. They were cooled as quickly as possible, kept at 32degrees-33degreesC for at least 48 h, and then slowly rewarmed. The patients were randomly assigned to either an arginine infusion (AI) group or a placebo group. Arginine infusion was started at the beginning of the rewarming process. The percentage of peripheral lymphocyte cells, phytohemagglutinin blastgenesis, growth hormone (GH), and prolactin (PRL) were all significantly higher in the AI group than in placebo group. Arginine-induced release of PRL and GH is possibly the most important immunologic effect. Arginine may also promote neurotoxicity via NO overproduction. There was no significant difference, however, in NO metabolite (NOx) concentration and mortality between the two groups. The AI group required significantly fewer days of ventilatory support (AI group, 15.0 +/- 4.7 days; placebo group, 18.9 +/- 5.1 days; P = 0.0475) and fewer days in the intensive care unit (ICU) (AI group, 10.5 +/- 1.9 days; placebo group, 12.9 +/- 2.8 days; P = 0.0153). In conclusion, patients with severe traumatic brain injuries who have undergone therapeutic brain hypothermia can benefit from arginine infusion, which has an immune-enhancing effect and reduces the need for ventilatory support and ICU care.