The Effective Dose of Remifentanil Combined with Remimazolam in Inhibiting Tracheal Intubation Responses in Elderly...

Hemodynamic instability during tracheal intubation in elderly patients poses significant perioperative risks. This study aimed to determine the effective doses (ED50/ED95) of remifentanil combined with remimazolam to suppress intubation-induced stress responses while minimizing hypotension in patients aged ≥60.

In this prospective, double-blind trial, 29 elderly patients received remimazolam (0.3 mg/kg) followed by rocuronium and remifentanil (initial dose: 1 µg/kg, adjusted via Dixon's up-down method). Hemodynamic parameters (blood pressure, heart rate, systemic vascular resistance, cardiac output) and bispectral index (BIS) were recorded. Probit regression analyzed dose-response relationships. A positive hemodynamic response was defined as an increase in systolic blood pressure or heart rate exceeding 20% of the baseline value within 5 minutes after endotracheal intubation. Dixon's up-and-down method and probit regression analysis to determine the ED50 and ED95 of remifentanil combined with remimazolam to suppress intubation-induced stress responses in elderly patients.

The ED50 and ED95 of remifentanil were 0.85 µg/kg (95% CI: 0.80-0.90) and 0.97 µg/kg (95% CI: 0.91-1.21), respectively. Positive responders showed elevated blood pressure at 30s-1 min post-intubation (P<0.05), while cardiac output and systemic vascular resistance remained comparable between groups. Hypotension incidence was low (14.3-20%), with transient BIS elevations (60-70) in 51.7% of patients but no intraoperative awareness.

In this exploratory dose-finding study, the estimated ED50 and ED95 of remifentanil for suppressing intubation-related hemodynamic responses during remimazolam-based induction were 0.85 and 0.97 μg/kg, respectively.