OBJECTIVES We compared the responses of the stress hormones, Cortisol, ACTH, vasopressin (AVP), corticotrophin releasing hormone (CRH) and catecholamines to elective conventional and laparoscopic cholecystectomy.
DESIGN A right upper quadrant transverse incision was used for conventional cholecystectomy, and four 1–2-cm incisions for the laparoscopic procedure (for insertion of surgical instruments, diathermy, fibreoptic telescope and light source, and carbon dioxide insufflation). Blood was sampled immediately prior to premedication (temazepam), after induction of anaesthesia (fentanyl and thiopentone) and at 10-minute intervals until the end of the procedure (N2O maintenance, vecuronium relaxation). A blood sample was taken after reversal, and then at 10-minute intervals for 50 minutes. Plasma sodium and blood pressure were measured at similar intervals. Results are expressed as mean ± standard error.
PATIENTS Twelve patients were studied (six in each group).
MEASUREMENTS Peptide hormones were measured by radioimmunoassay, Cortisol by ELISA and catecholamines by HPLC.
RESULTS The mean premedication hormone values for the conventional and laparoscopic procedures did not increase significantly after induction of anaesthesia. Within 10 minutes of the first incision, however, there was a marked concordant rise in mean plasma ACTH and AVP levels for both procedures (conventional: ACTH, from a premedication value of 10 2 ± 1 7 to 80 1 ± 14 3 pmol/l, AVP from 1 2 ± 0 4 to 117 ± 4 24 pmol/l, P<0 01 for both hormones; laparoscopic: ACTH from 5 8 ± 26 to 551 ± 260 pmol/l, AVP from 1 6 ± 0 11 to 49 2 ± 27 09 pmol/l). At the end of both types of operation mean levels of ACTH and AVP were still elevated, although the ACTH: AVP ratio had increased. Greater variability in ACTH and AVP responses was seen in the laparoscopic than in the conventional procedure, three patients showing a relatively small response to surgery. Total secretion of ACTH during both types of surgery was not significantly different but the total secretion of AVP was significantly less both during (P<0 05), and after (P<0 01) laparoscopic surgery. For both procedures, the timing of AVP and ACTH peaks was significantly related (P< 0 002). A small but significant rise in CRH was observed 30 minutes after the start of surgery for both procedures P <005). The timing of CRH and ACTH peaks was unrelated. The maximum mean plasma Cortisol level for the conventional procedure (1268 ± 147 nmol/l) was reached 20 minutes after reversal of anaesthesia and remained at this level until the end of sampling. The Cortisol response was comparable during the laparoscopic procedure but was beginning to fall at 60 minutes post-operatively. Plasma adrenaline responses to the two types of surgery were not significantly different, but the plasma total noradrenaline response to laparoscopic surgery as indicated by the response area during the first 20 minutes was significantly increased (P<0 02). Plasma sodium, renin activity and initial systolic blood pressure fall were not significantly different during the two procedures.
CONCLUSIONS For both procedures, the peak of ACTH secretion after incision is likely to be AVP dependent, and the timing of peak levels of these two hormones was significantly related. Subsequent ACTH secretion may be the result of an interaction between AVP and CRH. Laparoscopic cholecystectomy results in a smaller AVP rise than does the conventional procedure, and plasma AVP falls more rapidly post-operatively. During the period of observation, ACTH, CRH, Cortisol and adrenaline responses were not significantly lessened by the laparoscopic approach, but there was a significant increase in the noradrenaline response. Stress hormone monitoring may assist further improvements in surgical technique.