Sex differences in remifentanil requirements for preventing cough during anesthetic emergence.
OBJECTIVE
Target-controlled infusion (TCI) of remifentanil can suppress coughing during emergence from general anesthesia; nevertheless, previous studies under different clinical conditions recommend significantly different effective effect-site concentrations (effective Ce) of remifentanil for 50% of patients (EC₅₀). The differences among these studies include type of surgery and patient sex. In recent years, study of sex differences in regards to anesthetic pharmacology has drawn greater interest. Accordingly, we attempted to determine the effective Ce of remifentanil for preventing cough for each sex under the same clinical conditions.


METHODS
Twenty female and 25 male ASA physical status I-II grade patients between the ages of 20 and 46 years who were undergoing thyroidectomy were enrolled in this study. The effective Ce of remifentanil for preventing cough was determined for each sex using the isotonic regression method with a bootstrapping approach, following Dixon's up-and-down method.


RESULTS
Isotonic regression with a bootstrapping approach revealed that the estimated EC₅₀ of remifentanil for preventing coughing during emergence was significantly lower in females {1.30 ng/mL [83% confidence interval (CI), 1.20-1.47 ng/mL]} than in males [2.57 ng/mL (83% CI, 2.45-2.70 ng/mL)]. Mean EC₅₀ in females was also significantly lower than in males (1.23±0.21 ng/mL vs. 2.43±0.21 ng/mL, p<0.001). Mean arterial pressure, heart rate, and respiratory rate over time were not significantly different between the sexes.


CONCLUSIONS
When using remifentanil TCI for cough prevention during anesthetic emergence, patient sex should be a considered for appropriate dosing.
Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea.
Sarah
S
Soh
Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea. ; Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
Wyun Kon
WK
Park
Department of Surgery, Yonsei University College of Medicine, Seoul, Korea.
Sang Wook
SW
Kang
Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea.
Bo Ra
BR
Lee
Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, Korea. ; Anesthesia and Pain Research Institute, Yonsei University College of Medicine, Seoul, Korea.
Jeong Rim
JR
Lee
D000328:Adult; D000768:Anesthesia, General / Q000009:adverse effects*; D003371:Cough / Q000517:prevention & control*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010880:Piperidines / Q000008:administration & dosage* / Q000627:therapeutic use*; D000077208:Remifentanil; D012737:Sex Factors; D055815:Young Adult
D010880:Piperidines; D000077208:Remifentanil
Sex difference; cough prevention; effect-site concentration; general anesthesia; remifentanil; target-controlled infusion