OBJECTIVETo investigate the effects of different anesthesia depth on stress response in elderly patients undergoing elective laparoscopic surgery for colorectal cancer.

METHODSA total of 105 ASA I-III patients aged 60-91 years undergoing elective laparoscopic surgery for colorectal cancer with general anesthesia were randomized into 3 groups, namely group A with a target Narcotrend index (NI) maintained at D0 level, group B with a NI at D2 level, and group C with a NI at E1 level. The anesthetics (profopol and remifentanil) were adjusted according to Narcotrend monitoring results to maintain the specified anesthesia depth. The patients' heart rate (HR) and mean artery pressure (MAP) were recorded before anesthesia (T0), before intubation (T1), immediately after intubation (T2), at 2 min before pneumoperitoneum (T3), 2 min after pneumoperitoneum (T4), at the end of the surgery (T5) and extubation (T6). Serum levels of cortisol, adrenocorticotropic hormone (ACTH), endothelin-1 (ET-1), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and C-reactive protein (CRP) were measured by standard ELISA and radioimmunoassay before anesthesia (Ta), at the end of the surgery (Tb) and 1 day after the surgery (Tc).

RESULTSHR and MAP in group A increased significantly at T2, T4, and T6 compared to those at T0 (P<0.05), and were higher than those in group B and group C (P<0.05). The MAP in all the 3 groups all decreased at T1 and T3 (P<0.05 or P<0.01), and was markedly lower in group C than in groups A and B (P<0.05). The incidence of hypertension was significantly higher in group A than in groups B and C (P<0.05), while the incidence of hypotension was much higher in group C (P<0.01). There were no obvious differences in serum levels of cortisol, ACTH, CRP, IL-6, TNF-a, or ET-1 among the groups at Ta (P>0.05). The serum levels of ACTH in the 3 groups all significantly increased at Tb and Tc (P<0.01). CRP, IL-6 and TNF-a levels in group A were increased at Tb and Tc (P<0.05 or P<0.01) and significantly higher than those in groups B and C (P<0.05 or P<0.01). Cortisol in groups A and B increased at Tb and Tc (P<0.05) to a significantly higher level than that in group C (P<0.01). ET-1 level in group C at Tb and Tc was lower than those in groups A and B (P<0.05 or P<0.01).

CONCLUSIONSMaintaining the anesthesia depth for a NI at the D2 and E1 level can both attenuate the stress response in elderly patients undergoing laparoscopic surgery for colorectal cancer, but the hemodynamic stability can be better at a D2 level.