Effects of dexmedetomidine dosage on the short-term cognitive function of elderly patients undergoing cardiac surgery

This study aimed to investigate the effects of perioperative dexmedetomidine (DEX) infusion rates on the postoperative short-term cognitive function.

A total of 88 patients aged ≥ 60 years who underwent cardiac surgery from January 2022 to November 2022 at the First Affiliated Hospital of The University of Science and Technology of China (USTC) were included. Based on a single-center pilot analysis, patients were divided into two groups according to the rate of intraoperative DEX infusion, which started after tracheal intubation and continued until 1 h before extubation in the cardiac surgery intensive care unit. In Group L (n = 44), the infusion rate was 0.1-0.5 µg/kg/h (low-dose group), whereas in Group H (n = 44), the infusion rate was 0.5-0.9 µg/kg/h (high-dose group). Clinical outcomes were then compared between the groups. The Mini-Mental State Evaluation (abbreviated as MMSE₁, MMSE₂, MMSE₃, and MMSE₄) scale was used for the assessment of cognitive function, which was conducted on postoperative Days 2 (T₁), 7 (T₂), 14 (T₃), and 28 (T₄), with the score from postoperative Day 2 (MMSE₁) considered as the primary observation.

Patients in Group L had higher MMSE₁ scores compared to those in Group H (26.0 [24.0, 27.0] vs. 24.5 [22.0, 26.0], p = 0.046), and there was no significant difference in the scores between the groups at all subsequent time points. Group H exhibited a higher incidence of hypotension and bradycardia compared to Group L (p = 0.044 and p = 0.047, respectively).

Compared to a high dose (0.5-0.9 µg/kg/h) of DEX infusion, a low-dose (0.1-0.5 µg/kg/h) infusion started after induction of anesthesia and continued until 1 h before extubation improved postoperative cognitive function scores on postoperative Day 2 in patients aged 60 years and older.

URL: www.chictr.org.cn with registration number ChiCTR2100055093, registered on 31/12/2021.