Study objective: To compare remifentanil, an esterase-metabolized opioid, to a standard propofol-based sedation technique for monitored anesthesia care (MAC).
Design: Non-randomized, open label.
Setting: University hospital.
Patients: 44 healthy female outpatients undergoing breast biopsy procedures under local anesthesia.
Interventions: All patients received intravenous (IV) midazolam 2 mg, followed by a continuous infusion of either propofol 75 micrograms/kg/min, or remifentanil 0.1 microgram/kg/min, which was subsequently titrated to maintain optimal patient comfort without respiratory depression. Surgical-related pain was treated by injecting additional local anesthetic solution and "rescue" boluses of fentanyl 25 micrograms IV.
Measurements and main results: Sedation, pain, and discomfort were monitored using standardized rating scales at 1 to 5 minute intervals. Recovery times were measured from the end of the study drug infusions. Propofol resulted in significantly higher median sedation scores compared with remifentanil, with 73% of patients requiring a decrease in the propofol infusion rate because of "excessive" sedation. Local anesthetic requirements, pain, and discomfort scores during surgery were similar in both groups. Remifentanil resulted in greater respiratory depression compared with propofol, with decreases in the remifentanil infusion rate required by 41% of patients because of a slow respiratory rate (< 8 bpm) and/or oxygen desaturation measured by pulse oximetry (SpO2 < 90%). Median times to ambulation and to being judged "fit for discharge" were significantly shorter following propofol (40 and 47 minutes, respectively) compared with remifentanil (52 and 58 minutes, respectively).
Conclusion: Remifentanil provided comparable intraoperative conditions and patient comfort at a lower sedation level compared with propofol. However, remifentanil was associated with greater respiratory depression and a longer time to home readiness.