Effects of intraoperative hypothermia on stress hormone response in surgical patients

Background/Aim. Surgical stress itself, as well as hypo-thermia induced by general anesthesia and low ambient tem-perature, activates stress hormone response with changes in catecholamines and counter -regulatory hormones. The aim of this study was to investigate the acute hormone stress re-sponse in patients who underwent major surgical procedures and the efficiency of external and internal warming methods in alleviating these changes. Methods. The study included a total of 60 patients who underwent major open abdominal surgical procedures and were randomly divided into 4 groups: control non -warmed (C), externally warmed using forced -air warming mattress (W), internally warmed using in-travenous amino acids (A), and warmed with a combination of external and internal method (A+W). Esophageal temper-ature was used as a measure of core temperature. Concentra-tions of epinephrine, norepinephrine, cortisol, prolactin, and testosterone were measured. Blood samples for hormone measurement were obtained at two time points for catechol-amines - 90 min before and 120 min after finishing the sur-gery, and at additional two-time points for cortisol, prolactin, and testosterone (24 and 48 hrs after surgery). Results. In the W and A+W groups, the temperatures did not significant-ly differ between time points but constantly decreased in the C and A groups, with a statistically significant difference be-tween the anesthesia induction and the 120th min (35.61 +/- 042 vs. 33.86 +/- 0.71 degrees C;p < 0.000 and 35.81 +/- 0.54 vs. 34.45 +/- 0.41 degrees C; p < 0.000, respectively). Catecholamine concentra-tions in all groups showed a significant increase during sur-gery, with the highest values recorded in the non -warmed group (777.07 +/- 800.08 after vs. 106.13 +/- 89.63 pg/mL be-fore surgery for epinephrine and 1,349.67 +/- 984.16 vs. 580.53 +/- 465.38 for norepinephrine, p < 0.000). Concentrations of cortisol and prolactin also showed a significant increase at the same time point, with a tendency to normalize after 48 hrs. On the contrary, testosterone concentrations showed a de-crease after 120 min without normalization throughout the entire period of observation. Except for testosterone, changes in all stress hormones were attenuated in warmed groups compared to controls. Conclusions. Regarding both features of surgical stress investigated in this study (hypothermia and stress hormone response), the combination of endogenous amino acid -induced thermogenesis and external air warming mattress is most effective in its prevention.