[Risk of postoperative delirium in older adults under balanced general anesthesia]

Anesthetic depth can influence the incidence of postoperative delirium (POD). This depth is related to the potency of the volatile anesthetics used to maintain balanced general anesthesia. This potency is measured by means of the minimum alveolar concentration (MAC). In older adults, it is unknown which MAC is associated with the risk of POD.

To estimate the risk of POD associated with minimum alveolar concentration (MAC) levels of volatile anesthetics in older adults who received balanced general anesthesia.

A prospective cohort study was carried out with 119 patients, aged ≥ 60 years, with 0 points in the 4 "As" test (4AT), without neurological or psychiatric diseases. During the intraoperative period, the CAM provided was recorded, and in the postoperative period, the presence of emergency with delirium and/or POD was evaluated at 2 and 24 hours, considering a score ≥ 4.

A longer hospital stay was found in the group that received a MAC ≥0.9. The incidence of POD was 29.4%. Those who received a MAC ≥ 0.9 had an RR of 2.22 (95%CI: 1.2-4.2) of presenting POD. An adjusted logistic regression model was performed with the variables female sex (OR: 4, 95%CI: 1.5-10.4), ASA physical status 3-4 (OR: 3.7, 95%CI: 1.5-9) and MAC ≥ 0.9 (OR: 3.1 95%CI: 1.2-8) with an R2: 0.26 and a constant of 3.005.

MAC ≥ 0.9 represents a risk factor for DPO, so individualized dosing of volatile anesthetics should be used.