Optimal effective-site concentration of remifentanil for sedation during plate removal of maxilla

Abstract

Background: Removal of the plate following Le Fort I osteotomy and BSSO (bilateral sagittal split osteotomy) is a common procedure. However, patients who undergo plate removal experience intense pain and discomfort. This study investigated the half-maximal effective concentration (Ce₅₀ ) of remifentanil in the prevention of plate removal pain under sedation using dexmedetomidine.

Methods: The study evaluated 18 patients, between 18 and 35 years of age, scheduled for elective surgery. Remifentanil infusion was initiated after sedation using dexmedetomidine, and started at a dose of 1.5 ng/mL on the first patient via target-controlled infusion (TCI). Patients received a loading dose of 1.0 µg/kg dexmedetomidine over 10 min, followed by a maintenance dose of 0.7 µg/kg/h. When the surgeon removed the plate, the patient Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score was observed.

Results: The Ce of remifentanil ranged from 0.9 to 2.1 ng/mL for the patients evaluated. The estimated effect-site concentrations of remifentanil associated with a 50% and 95% probability of reaching MOAA/S score of 3 were 1.28 and 2.51 ng/mL, respectively.

Conclusions: Plate removal of maxilla can be successfully performed without any pain or adverse effects by using the optimal remifentanil effect-site concentration (Ce₅₀ , 1.28 ng/mL; Ce₉₅ , 2.51 ng/mL) combined with sedation using dexmedetomidine.

Keywords: Conscious Sedation, Dexmedetomidine; Plate Removal; Remifentanil.

Fig. 1. Predicted probability of reaching a Modified Observer's Alertness/Sedation (MOAA/S) score of 3 plotted against the effect-site concentrations of remifentanil. X: Effect-site concentration of remifentanil when an MOAA/S score of 3 was not reached; O: effect-site concentration of remifentanil of that reached an MOAA/S score of 3. The red solid line indicates the population prediction.