Thermoregulatory effects of perioperative intravenous amino acid infusion in patients undergoing TURP under spinal anesthesia

ABSTRACT

Hypothermia during anesthesia is associated with many postoperative complications. Therefore, many ways to avoid intraoperative hypothermia have been developed, usually by minimizing heat loss. Anesthetic agents suppress oxidative metabolism. Amino acids enhance thermogenesis by stimulating this metabolism. Forty-five adult patients were randomized into 3 groups each included 15 patients. Group A received intravenous amino acid infusion for 1 hour before spinal anesthesia and continuing throughout the first hour intraoperatively, Group B received intravenous amino acid infusion for 1 hour after the onset of spinal anesthesia and Group C received volumes of nutrient-free saline solution infused for 1 hour before and during first hour of anesthesia. Tympanic membrane core temperature and mean skin temperature were measured every 15 minutes during the 1[st] hour then after 120 minutes from the onset of spinal anesthesia. Plasma osmolality and serum lactate were measured in the 3 groups. Shivering, TUR Syndrome and total hospital stay were also assessed. Mean final core temperature, 120 minutes after induction of spinal anesthesia was 37.1 +/- 0.29°C in group A, 36.7 +/- 0.31°C in group B and 35.5 +/- 0.34°C in group C [P<0.05]. The increased level of oxygen consumption in the amino acid groups compared with the saline group was preserved even after the onset of anesthesia. The thermal vasoconstriction threshold, the tympanic membrane temperature that triggered a rapid increase a skin temperature gradient, was increased in group A [36.55 +/- 0.48°C] in comparison to group B [36.34 +/- 0.47°C] and group C [35.02 +/- 0.45°C]. Plasma osmolality was higher in groups A and B in comparison to group C [P<0.05]. Serum lactate was higher in group C in comparison to both A and B [P<0.05]. The incidence of shivering and the total hospital stay were higher in group C than in groups A and B [P<0.05]. Amino acid infusion in the preopferative period for anesthesia for TURP, prevents spinal anesthesia-induced hypothermia by increasing the metabolic rate and core temperature for peripheral thermal vasoconstriction