Median Effective Concentration of Ropivacaine for Femoral Nerve Block Maintaining Motor Function During Knee Arthroscopy in Two Age Groups

Yan-Lei Tai; Li Peng; Ying Wang; Zi-Jun Zhao; Ya-Nan Li; Chun-Ping Yin; Zhi-Yong Hou; De-Cheng Shao; Ya-Hui Zhang; Qiu-Jun Wang

doi:10.2147/JPR.S357750

Median Effective Concentration of Ropivacaine for Femoral Nerve Block Maintaining Motor Function During Knee Arthroscopy in Two Age Groups

J Pain Res. 2022 Jun 7:15:1647-1657. doi: 10.2147/JPR.S357750. eCollection 2022.

Authors

Yan-Lei Tai¹, Li Peng¹, Ying Wang², Zi-Jun Zhao³, Ya-Nan Li¹, Chun-Ping Yin¹, Zhi-Yong Hou⁴, De-Cheng Shao⁵, Ya-Hui Zhang¹, Qiu-Jun Wang¹

Affiliations

¹ Department of Anesthesiology, Third Hospital Affiliated to Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China.
² Department of Anesthesiology, Tangshan Gongren Hospital, Tangshan, Hebei, People's Republic of China.
³ Department of Anesthesiology, Hebei Chest Hospital, Shijiazhuang, Hebei, People's Republic of China.
⁴ Center of Emergency and Trauma, Third Hospital Affiliated to Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China.
⁵ Department of Sport Medicine, Third Hospital Affiliated to Hebei Medical University, Shijiazhuang, Hebei, People's Republic of China.

Abstract

Background: Femoral nerve block combined with general anesthesia is commonly used for patients undergoing knee arthroscopy in ambulatory care centers. An ideal analgesic agent would selectively (differentially) block sensory fibers, with little or no effect on motor nerves. Ropivacaine is considered to cause less motor block than others. This study investigated the median effective concentration (EC₅₀) of ropivacaine for differential femoral nerve block in adults either younger or older than 60 years.

Methods: Patients with American Society of Anesthesiologists physical status I-III and scheduled for knee arthroscopy were categorized as 18- to 60-years-old (Group 1), or older than 60 years (Group 2). Surgeries were performed under general anesthesia combined with femoral nerve block via 22 mL ropivacaine. The EC₅₀ of ropivacaine for differential femoral nerve block was determined using the up-and-down method and probit regression. The primary outcome was the EC₅₀ (95% confidence interval [CI]) of the 2 groups. Data on the sensory block, analgesic effect, complications, and hemodynamics during surgery were also recorded.

Results: The EC₅₀ of 22 mL ropivacaine for differential femoral nerve block of Group 1 (0.124%, 95% CI 0.097-0.143%) was significantly higher than that of Group 2 (0.088%, 95% CI 0.076-0.103%). The sensory block and hemodynamic data of the 2 groups were comparable. None of the patients experienced neurological complications.

Conclusion: The EC₅₀ of ropivacaine administered for differential femoral nerve block during knee arthroscopy was lower in patients older than 60 years, relative to younger adults.

Keywords: EC50; age groups; femoral nerve block; motor block; ropivacaine.

Grants and funding

This work is supported by the National Natural Science Foundation of China (81771134), Hebei Province Technology Innovation Guide Project Science and Technology Winter Olympics Special Project (19977790D), and the Professional Capacity Building and Specialist Training Program Funded by Hebei Provincial Government. The funding bodies had no role in the design of the study, the collection, analysis, or interpretation of the data, or writing the manuscript.