The differential impact of volatile and intravenous anaesthetics on stress response in the swine.

OBJECTIVE

To compare the effects of various anaesthetics on stress response in the presence and absence of surgical stimulation.

DESIGN

Twenty-nine pigs scheduled to undergo surgical central vein catheter placement were randomly allocated to receive only sedation with ketamine-midazolam (group SHAM, n=5) or general anaesthesia with either propofol 8 mg/kg/h (group PROP, n=8), sevoflurane 1.0 MAC (group SEVO, n=8) or desflurane 1.0 MAC (group DESF, n=8). Following surgery, anaesthesia was maintained for a total period of 4 hours. Thyroid hormones, noradrenaline, cortisol, corticotrophin (ACTH), beta-endorphin, interleukin-1beta and -6 and tumor necrosis factor-alpha were determined by appropriate methodology after premedication (t0), after surgical procedure (t1) and at the end of 4h (t2).

RESULTS

At t1 ACTH and beta-endorphin increased in all groups, thyroxin in groups SEVO, DESF and PROP, noradrenaline in group SEVO and cortisol in the SHAM and PROP groups. At t2 cortisol and ACTH levels were lower in the PROP compared to SEVO group. Serum cytokines were not significantly altered in either group.

CONCLUSIONS

The choice of the general anaesthetic did not affect thyroid hormones levels in either the presence or absence of surgical stimulus. In the presence of surgical stimulation, sevoflurane resulted in higher noradrenaline levels and in higher activity of the ACTH-cortisol axis compared to propofol.