TNF alpha released in the early post-operative period is influenced by anaesthesia

In this study we tested for TNF alpha concentrations 45 subjects undergoing elective prostatectomy performed under two different anaesthetic regimens. In addition, given the influence of neuroendocrine axis on immunological homeostasis, we also determined post surgery cortisol and norepinephrine levels. The patients were randomly assigned to one of two groups: group 1 (no. = 24) received NLA general anaesthesia, whereas group 2 (no. = 21) received spinal analgesia. Blood samples were drawn the day before surgery (t0), at two (t1), at 24 (t2), at 48 (t3) and 72 (t4) hours from the completion of operation. In the patients assigned to the general anaesthesia group an increase of circulating TNF alpha was detected through t1 to t4. In the spinal group TNFa values did not change in t1 and t2, whereas enhanced levels of the cytokine--overlapping with those of group 1--were observed at 48 and 72 hrs following surgery. Cortisol response increased in both the groups, peaking at t1 but, at this time patients undergoing spinal anaesthesia were found to have significantly lower circulating cortisol. A rise of plasma norepinephrine was observed at t1 in the general anaesthesia group alone. For the early TNF alpha increase, observed in group 1 only, we hypothesize that anaesthetics, such as NLA agents, may trigger a TNF alpha release in vivo. Alternatively TNF alpha production may represent the result of the neuroendocrine response such as cortisol and norepinephrine, to the surgical/anaesthetic trauma which could be blocked by subarachnoid anaesthesia. Conversely, the late TNF alpha increase found in all the patients studied might be explained by postoperative infections as well as by inflammation of the injured tissues and/or normal wound healing.