[Changes in the concentrations of catecholamines and cortisol in balanced anesthesia and total intravenous anesthesia].

OBJECTIVE

To compare hormone response to stress caused by surgery performed under balanced general anesthesia and total intravenous anesthesia.

PATIENTS AND METHOD

Two randomly formed groups of 24 patients each were studied. All patients were scheduled for lumbar laminectomy to correct disc hernias, with one group receiving balanced anesthesia with isoflurane (expiratory fraction between 0.5% and 0.6%), and the second group receiving total intravenous anesthesia (TIVA) (propofol infusion changed every 10 min from 12 to 6 mg/kg/h). Analgesics and relaxants were given by continuous infusion at preestablished doses (fentanyl 2 micrograms/kg/h; vecuronium 0.05 mg/kg/h). Cortisol and catecholamine (adrenalin, noradrenaline and dopamine) levels were determined at the following times: the morning of surgery (baseline), 5 min after intubation, 5 min after incision, 30 and 60 min after intubation; 5 min after tube removal and upon admission to the recovery unit.

RESULTS

Cortisol levels decreased from baseline (14 +/- 3 pg/ml) until 30 min after intubation (4 +/- 2 pg/ml; p < 0.05) in the balanced anesthesia group. Adrenaline levels followed the same pattern (baseline 77 +/- 7 versus 57 +/- 10 pg/ml 30 min after intubation). Dopamine levels were statistically different (p < 0.05) at baseline (42 +/- 3 pg/ml), after intubation (38 +/- 2 pg/ml) and after incision (35 +/- 3 pg/ml), but the difference disappeared 30 minutes after intubation (38 +/- 8 pg/ml). Noradrenaline levels after incision (425 +/- 116 pg/ml) were significantly different from those at baseline (671 +/- 124 pg/ml), and the difference was evident until 60 min after incision. In the TIVA group we found significantly higher cortisol levels after intubation (21 +/- 0 pg/ml) than after baseline (14 +/- 2 pg/ml); this level decreased after extubation (7 +/- 0 pg/ml; p < 0.05). Adrenaline levels were significantly higher than at baseline (64 +/- 11 pg/ml) at times corresponding to intubation (76 +/- 5 pg/ml) and extubation (48 +/- 5 pg/ml). Noradrenaline increased significantly over baseline (497 +/- 99 pg/ml) after incision (597 +/- 90 pg/ml) and decreased significantly after 30 min. The increases in cortisol were significantly greater in the TIVA group than in the control group after intubation (21 +/- 0 versus 8 +/- 3 pg/ml, respectively) after intubation, after incision (18 +/- 2 versus 6 +/- 3 pg/ml) and 30 minutes after intubation (15 +/- 2 versus 4 +/- 2 pg/ml). Similar differences were found for dopamine after intubation (49 +/- 2 versus 38 +/- 2 pg/ml) and after incision (45 +/- 5 versus 35 +/- 3 pg/ml).

CONCLUSIONS

Hormone levels are significantly higher during intravenous anesthesia than during balanced anesthesia, and the difference is evident from the earliest measurement performed.