Last update:
20-Apr-2012

OBJECTIVE The surgical stimulus induces oxidative stress, mainly by superoxide release. This study examined the biological effects of general and combined general-spinal anesthesia on the neuroendocrine response to surgical procedure.

METHOD The study included 30 healthy Landrace pigs of weight 20±2 kg, which underwent median subumbilical incision for peritoneal lavage (DPL). The pigs were randomized into two groups, the first of which (14 pigs) received general anesthesia and the second (16 pigs) general and spinal anesthesia. In the second group the spinal block level was assessed by pinprick. Continuous hemodynamic monitoring was conducted during the study. Venous blood samples were taken at three time points: Before induction of general anesthesia (baseline), after general or general-spinal anesthesia, and after DPL to measure total oxidative capacity (Perox) and serum level of IL-4 by ELISA.

RESULTS In the second group of pigs the pinprick block level after spinal anesthesia was lower than T8. No significant hemodynamic differences between the two groups were observed during the study. No statistical significant differences were found in the serum IL-4 levels at the three time points, between the groups receiving the two types of anesthesia. In the general anesthesia group, the increase of Perox levels was statistically significant after anesthesia (p=0.026) and the decrease of Perox levels was statistically significant after DPL (p=0.045). In the general-spinal anesthesia group, no significant difference in Perox levels was observed during the procedure.

CONCLUSIONS The study findings suggest that spinal anesthesia attenuates the oxidative response to surgical procedure when compared to general anesthesia. The degree of surgical stress in the swine model, as reflected by the oxidative status may be influenced by afferent neural block.

Key words: Combined anesthesia, Neuroendocrine response, Stress.