The median effective concentration of remifentanil to inhibit pupillary reflex dilation induced by endotracheal intubation.
Am J Transl Res 2022;
14:7898-7906. [PMID:
36505339 PMCID:
PMC9730105]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/15/2022] [Indexed: 12/15/2022]
Abstract
OBJECTIVE
To determine the median effective concentration (EC50) of remifentanil to inhibit pupillary reflex dilation (PRD) induced by endotracheal intubation using a modified sequential test method.
METHODS
In this prospective study, 34 patients undergoing elective surgery under general anesthesia were selected. The induction of anesthesia was started using propofol with an effect-site concentration (Ce(pro)) of 4.0 μg/mL. The effect-site concentration of remifentanil (Ce(Remi)) was set according to the modified sequential test method, with 0.42 ng/mL as the initial concentration for the first patient. The gradient ratio was 1.1. The Ce(Remi) of each patient was determined by whether the PRD of the previous patient disappeared during endotracheal intubation. If the PRD disappeared, a lower concentration was applied. Otherwise, a higher concentration was applied. The experiment ended after 9 crosses of PRD disappearance-presence and PRD presence-disappearance. The EC50 of remifentanil and 95% confidence interval (CI) were calculated using the Dixon and Massey's method. The Probit regression procedure was used to derive the EC50, 95% effective concentration (EC95) of remifentanil and their 95% CIs.
RESULTS
The EC50 of remifentanil to inhibit PRD induced by endotracheal intubation was 4.41 ng/mL (95% CI, 4.32 to 4.49 ng/mL) and the EC95 was 5.24 ng/mL (95% CI, 4.78 to 7.68 ng/mL). In 34 patients, the time to reach the maximum change in heart rate, systolic blood pressure, mean arterial pressure and Bispectral index was 75.00 (60.00-98.00) s, 95.00 (75.00-133.00) s, 95.00 (75.00-135.00) s, and 100.00 (78.00-113.00) s, respectively, which was significantly longer than the time (42.00 (25.00-47.00) s) needed for pupillary diameter (P<0.05).
CONCLUSION
The EC50 of remifentanil to inhibit PRD induced by endotracheal intubation was 4.41 ng/mL and the EC95 was 5.24 ng/mL. The time to reach the maximum pupillary diameter change was shorter than the time needed for heart rate, blood pressure, and Bispectral index. This prospective study was registered in the China Clinical Trials Registration Center (ChiCTR2100043771, https://www.chictr.org.cn).
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