Abstract: Objective To investigate the effects of different anesthesia depth on stress response in elderly patients undergoing
elective laparoscopic surgery for colorectal cancer. Methods A 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). Results HR 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). Conclusion Maintaining 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.