Targeting smooth emergence: the effect site concentration of remifentanil for preventing cough during emergence during propofol-remifentanil anaesthesia for thyroid surgery.
BACKGROUND
The administration of short-acting opioids can be a reliable and safe method to prevent coughing during emergence from anaesthesia but the proper dose or effect site concentration of remifentanil for this purpose has not been reported. We therefore investigated the effect site concentration (Ce) of remifentanil for preventing cough during emergence from anaesthesia with propofol-remifentanil target-controlled infusion.


METHODS
Twenty-three ASA I-II grade female patients, aged 23-66 yr undergoing elective thyroidectomy were enrolled in this study. EC(50) and EC(95) of remifentanil for preventing cough were determined using Dixon's up-and-down method and probit analysis. Propofol effect site concentration at extubation, mean arterial pressure, and heart rate (HR) were compared in patients with smooth emergence and without smooth emergence.


RESULTS
Three out of 11 patients with remifentanil Ce of 1.5 ng ml(-1) and all seven patients with Ce of 2.0 ng ml(-1) did not cough during emergence; the EC(50) of remifentanil that suppressed coughing was 1.46 ng ml(-1) by Dixon's up-and-down method, and EC(95) was 2.14 ng ml(-1) by probit analysis. Effect site concentration of propofol at awakening was similar in patients with a smooth emergence and those without smooth emergence, but HR and arterial pressure were higher in those who coughed during emergence. Clinically significant hypoventilation was not seen in any patient.


CONCLUSIONS
We found that the EC(95) of effect site concentration of remifentanil to suppress coughing at emergence from anaesthesia was 2.14 ng ml(-1). Maintaining an established Ce of remifentanil is a reliable method of abolishing cough and thereby targeting smooth emergence from anaesthesia.
Department of Anaesthesiology and Pain Medicine, Yonsei University College of Medicine, 250 Seongsan-no, Seodaemun-gu, Seoul 120-752, Korea. leejeongrim@gmail.com
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D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000762:Anesthesia Recovery Period; D018686:Anesthetics, Intravenous; D003371:Cough / Q000517:prevention & control*; D020878:Device Removal; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008875:Middle Aged; D010880:Piperidines / Q000008:administration & dosage*; D011183:Postoperative Complications / Q000517:prevention & control; D015742:Propofol; D000077208:Remifentanil; D013965:Thyroidectomy; D055815:Young Adult
D000701:Analgesics, Opioid; D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol