Effect of type of anesthesia and lower-abdominal laparotomy in mice on the cytokine response to acute stress.

Abstract

Recent emphasis has been placed on the accuracy of systemic cytokine levels as an index to the severity of acute surgical stress. In this investigation, a murine animal model was developed to determine the effect of the type of anesthesia on the cytokine response to a standard surgical stress. The initial phase was designed to assess the severity of the acute stress response to a standard surgical stimulus by measuring the release of proinflammtory cytokines in 30 Balb C mice subjected to halothane anesthesia and exploratory laparotomy. The severity of the operative stress was assessed by serum levels of epinephrine and C-reactive protein at 0, 1, 2, 4, and 6 hours and compared with systemic levels of interleukin-1, interleukin-6, and tumor necrosis factor-alpha. In the next phase, in order to assess the stress response associated with the induction of anesthesia without surgery. IL-6 was measured in 10 mice undergoing halothane anesthesia or combined halothane-spinal anesthesia. In the final series of experiments, designed to assess the effect of anesthetic type on the stress response induced by the standard surgical stress, 40 mice underwent halothane anesthesia with laparotomy or combined halothane-spinal anesthesia with laparotomy. Following exploratory laparotomy, serum epinephrine was significantly elevated at 2 hours (P < .05 vs time 0), while C-reactive protein became elevated at 6 hours (P < .05). Serum interleukin-6 rose rapidly, reaching a peak at hour 2 (P < .001) and then declining through hour 6, but interleukin-1 and tumor necrosis factor, were elevated in only a few animals undergoing laparotomy. Neither halothane nor combined halothane/spinal anesthesia had any effect on the interleukin-6 stress response in the absence of surgical stress. Similarly, the degree of operative stress after exploratory laparotomy was not affected by the type of anesthesia. Serum interleukin-6 was the best marker for acute surgical stress, which could not be induced by anesthetic interventions alone. The combination of halothane with spinal anesthesia was not able to attenuate the degree of stress as compared with halothane anesthesia alone in animals undergoing abdominal surgery.