INTRODUCTION: There seems to be bidirectional communications between neuroendocrine and immune systems. Author have undertaken this study to see if the choice of anesthesia(preemptive epidural anesthesia) can directly or indirectly provide immunomodulation for cytokines and determine the relationship of cytokines and hypothalamo-pituitary-adrenal axis in stomach cancer surgery patients. We also attempted to see whether the amount of morphine administration and choice of analgesia (continuous epidural vs. IV-PCA) can influence cytokine release, and possibly immunity,
METHODS: Total 19 gastric cancer surgery patients were randomly assigned in double-blindfashion into two groups. Group-G(n=9) was provided with general anesthesia plus MorphineIV-PCA analgesia, meanwhile Group-GE(n=10) with preemptive epidural and general anesthesia plus continuous epidural analgesia for postoperarive pain control. At predetermined time interval of preoperative and 1, 3, 6, 24, 48 and 72 hours post skin incsion, various parameters including proinflammatory cytokines (Interleukin 1beta, Interleukin 6, TNFalpha) and stress hormones(ACTH, cortisol, epinephrine norepinephrine) were evaluated along with vital signs and visual analog pain scale. Simultaneous assessments of operating and anesthesia time, total morphine doses, the time to recovery of gastrointestinal function and incidences of complications were made.
RESULTS: Demographic data demonstrated no differences. Time periods of operation and anesthesia were similar. Total morphine doses were approximately four times greater in Group-G. The time of recovery of gastrointestinal function revealed no meaningful significances. Secretions of Interleukin-1beta and TNFalpha were blocked by preemptive epidural anesthesia, meanwhile Interleukin-6 as well as ACTH and cortisol showed no such finding. Epinephrine and norepinephrine could only be partially blocked in Group-GE. After 24 hours post skin incision, the differences of cytokines and ACTH and cortisol between two groups were dissipated. In spite of these hormonal findings, vital signs and visual analog pain scale could not disclose any differences. Incidences of complications were statistically insignificant except higher incidence of itching in Group-GE. For postoperarive pain management, the amounts of morphine administered by continuous epidural analgesia or IV-PCA demonstrated no evidence of immunosuppression.
DISCUSSION: Taken all together, preemptive epidural anesthesia can partially block only some of cytokines and stress hormones and these effects dose not have clinically relevant long term influence. Morphine, given at clinical dose range does not suppress immunity, regardless of choice of analgesic techniques.
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