Ying Deng,1,2,* Liwei Wang,1,2,* Hua Zhang,3 Zhichao Xu,4 Ling Jiang,5 Yang Zhou1,2,6 

1Department of Anesthesiology, Peking University Third Hospital, Beijing, People’s Republic of China; 2Beijing Center of Quality Control and Improvement on Clinical Anesthesia, Beijing, People’s Republic of China; 3Research Center of Clinical Epidemiology, Peking University Third Hospital, Beijing, People’s Republic of China; 4Department of Anesthesiology, Xuancheng People’s Hospital, Xuancheng City, Anhui Province, People’s Republic of China; 5Ultrasound Diagnosis Department, Peking University Third Hospital, Beijing, People’s Republic of China; 6Anesthesia and Perioperative Medicine Branch of China International Exchange and Promotive Association for Medical and Health Care, Beijing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Yang Zhou, Department of Anesthesiology, Peking University Third Hospital, No. 49, North Garden Street, Haidian District, Beijing, 100191, People’s Republic of China, Tel/Fax +8610-82267260, Email zhouyang@pku.edu.cn Ling Jiang, Department of Anesthesiology, Peking University Third Hospital, No. 49, North Garden Street, Haidian District, Beijing, 100191, People’s Republic of China, Tel/Fax +8610-82267260, Email papayaling@163.com

Background: This study aims to evaluate the degree of diaphragmatic paralysis by assessing diaphragmatic excursion and pulmonary function following an ultrasound-guided interscalene brachial plexus block with two different concentrations of ropivacaine (0.2% and 0.5%).
Methods: Forty patients undergoing shoulder arthroscopic surgery were randomly assigned to receive ultrasound-guided interscalene brachial plexus block with 20 mL of either 0.2% or 0.5% ropivacaine. Diaphragmatic excursion (DE) and diaphragm thickening fraction (TF) were measured using M-mode ultrasound before and 30 minutes after the block. Pulmonary function was assessed using a portable spirometer. Additional outcomes included pain scores and the occurrence of adverse effects.
Results: DE was significantly reduced 30 minutes after block in the 0.5% group compared to the 0.2% group (p< 0.01), as well as the TF (p< 0.01). Forced vital capacity (FVC) was also significantly reduced in the 0.5% group 30 minutes after block in the preparation room compared to the 0.2% group (p< 0.001). Both 0.2% and 0.5% ropivacaine had similar effects in improving postoperative pain. There were no serious block-related complications in either group.
Conclusion: 0.2% ropivacaine may impair pulmonary function less than 0.5% ropivacaine. The clinical significance of these differences requires further investigation.

Keywords: interscalene brachial plexus block, ropivacaine, diaphragmatic paralysis, diaphragmatic excursion, thickening diaphragm fraction