Comparative Efficacy of Low-Dose Ketamine Versus Midazolam Co-Induction on Hemodynamic Stability and Early Neurocognitive Recovery in Geriatric Anesthesia: A Randomized Double-Blind Pilot Trial

Abstract

Background. Older patients are prone to hypotension after induction and to early postoperative cognitive decline. Midazolam, the conventional co-induction sedative, may prolong sedation in older adults; ketamine preserves sympathetic tone.

Objective. To compare low-dose ketamine with midazolam co-induction for hemodynamic stability, propofol requirement, and early neurocognitive recovery in older surgical patients.

Methods. In this randomized, double-blind pilot trial, 32 patients aged ≥ 65 years (ASA II–III) undergoing elective surgery under general anesthesia received ketamine 0.3 mg/kg (Group K, n = 16) or midazolam 0.075 mg/kg (Group M, n = 16) before titrated propofol induction. The primary outcome was the change in Mini-Mental State Examination (MMSE) score from baseline to 1 hour after extubation. Secondary outcomes were mean arterial pressure (MAP), hypotension, propofol dose, and extubation time.

Results. The MMSE declined by 1.1 ± 0.8 points in Group K and 4.2 ± 1.4 points in Group M (p < 0.001); cognitive dysfunction (decline > 2 points) occurred in 18.8% and 68.8% (p = 0.004). Post-induction MAP was 88.5 ± 7.4 and 76.2 ± 8.8 mmHg (p < 0.001), and hypotension occurred in 12.5% and 56.3% (relative risk 0.222, 95% confidence interval 0.057–0.872; p = 0.009). Group K needed 32.1% less propofol (1.12 ± 0.18 vs. 1.65 ± 0.22 mg/kg, p < 0.001) and was extubated sooner (8.4 ± 2.1 vs. 14.2 ± 3.5 minutes, p < 0.001).

Conclusion. In this pilot trial, ketamine co-induction was associated with more stable hemodynamics, less propofol, and a smaller early MMSE decline than midazolam.