[Beta-endorphin and substance P in the perioperative period]

The modifying impact of anaesthesia on the stress reaction related to surgical trauma was investigated on the basis of the neuropeptidergic parameters of 66 patients who had to undergo a gynaecological radical operation. Anaesthesia was either performed as neuroleptanaesthesia or as epidural analgesia by using bupivacaine in combination with general anaesthesia. The plasma concentrations of substance P and beta-endorphin were taken as neuropeptidergic parameters. Both regulatory peptides show numerous corresponding synergisms. An acceleration of these neuropeptide systems is assumed to be present in severe disturbance of homeostasis. Plasma concentrations of substance P and beta-endorphin were examined at 11 measuring points in the perioperative and intraoperative periods. The plasma concentration of substance P significantly declines in the preoperative period while the concentration of beta-endorphin in the plasma remains at a relatively constant level. In the dynamics of beta-endorphin in the plasma significant differences between the two anaesthetic techniques become apparent in the intraoperative period. Those patients given epidural analgesia have a significantly higher maximum concentration at a later date. This difference is attributed to the possible loss of the adrenal medullary function due to partial sympathetic blocking. Single observations in patients pregnant in the last trimester testify to an extraordinary adaptability at the end of pregnancy.