Korean J Anesthesiol.  2014 Jan;66(1):39-43. 10.4097/kjae.2014.66.1.39.

Optimal effect-site concentration of remifentanil when combined with dexmedetomidine in patients undergoing cystoscopy

• Heo B
• Kim M
• Lee H
• Park S
• Jeong S

• KMID: 2237242
• DOI: http://doi.org/10.4097/kjae.2014.66.1.39

Abstract

BACKGROUND
Cystoscopic procedure is a very common practice in the field of urology due to its ability to survey the bladder for a variety of indications. However, patients who undergo cystoscopy feel intense pain and discomfort. This study investigated the half maximal effective concentration (EC50) of remifentanil in preventing cystoscope insertion pain under sedation using dexmedetomidine.
METHODS
The study was prospectively conducted on 18 male patients, aged 18 to 65. Remifentail infusion was initiated together with dexmedetomidine, and started at a dose of 2.4 ng/ml on the first patient. The effect-site concentration (Ce) of remifentanil for each subsequent patient was determined by the previous patient's response using Dixon's up-and-down method with an interval of 0.3 ng/ml. Patients received a loading dose of 1.0 microg/kg dexmedetomidine over 10 minutes, followed by a maintenance dose of 0.6 microg/kg/hr. After the patient's OAA/S score (Observer's Assessment of Alertness/Sedation scale) reached 3-4, and the Ce of remifentanil reached target concentration, the urologist was allowed to insert the cystoscope and the pain responses were observed.
RESULTS
The effect-site concentration of remifentanil required to prevent cystoscope insertion pain in 50% of patients under sedation using dexmedetomidine was 1.30 +/- 0.12 ng/ml by Dixon's up-and-down method. The logistic regression curve of the probability of response showed that the EC50 and EC95 values (95% confidence limits) of remifentanil were 1.33 ng/ml (1.12-1.52 ng/ml) and 1.58 ng/ml (1.44-2.48 ng/ml), respectively.
CONCLUSIONS
Cystoscopic procedure can be carried out successfully without any pain or adverse effects by optimal remifentanil effect-site concentration (EC50, 1.33 ng/ml; EC95, 1.58 ng/ ml) combined with sedation using dexmedetomidine.

Keyword

Cystoscopy; Dexmedetomidine; Monitored anesthesia care; Remifentanil

MeSH Terms

Cystoscopes
Cystoscopy*
Dexmedetomidine*
Humans
Logistic Models
Male
Prospective Studies
Urinary Bladder
Urology
Dexmedetomidine