AUTHOR=Huang Xiao-Dong , Qiu Xiao-Xiao , Wang He-Jie , Jin Xia-Fang , Xiao Fei 

TITLE=A prospective randomized double-blind study comparing the dose-response curves of epidural ropivacaine for labor analgesia initiation between parturients with and without obesity

JOURNAL=Frontiers in Pharmacology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1348700

DOI=10.3389/fphar.2024.1348700

ISSN=1663-9812

ABSTRACT=<p><bold>Background:</bold> Previous studies have explored the median effective concentration (EC50) of ropivacaine for labor epidural analgesia in parturients with obesity. However, the clinical relevance of the 90% effective concentration (EC90) remains unclear. This study aimed to determine and compare the dose–response curve of epidural ropivacaine for labor analgesia between parturients with and without obesity.</p><p><bold>Methods:</bold> Parturients were divided into two groups based on body mass index (BMI): group N, consisting of parturients with BMI &lt;30 kg/m<sup>2</sup>, and group O, consisting of parturients with BMI &gt;30 kg/m<sup>2</sup>. Within each group, the patients were randomized to receive one of five concentrations (0.0375%, 0.075%, 0.1125%, 0.15%, or 0.1875%) of epidural ropivacaine for labor analgesia. Analgesia was induced with a loading dose of 15 mL of the assigned concentration. Visual analogue scale (VAS) scores were recorded at baseline and 30 min post-dose to calculate the response (%) using the formula [(baseline VAS pain score—VAS pain score at 30 min)/baseline VAS pain score] ×100%. The EC50 and EC90 values were determined via nonlinear regression analysis.</p><p><bold>Results:</bold> The EC50 and EC90 values of ropivacaine were 0.061% (95% confidence interval [CI], 0.056%–0.066%) and 0.177% (95% CI, 0.152%–0.206%) in group N and 0.056% (95% CI, 0.051%–0.061%) and 0.161% (95% CI, 0.138%–0.187%) in group O, respectively. No significant differences were observed in the EC50 and EC90 values between the two groups (<italic>p</italic>-values = 0.121 and 0.351, respectively.</p><p><bold>Conclusion:</bold> In conclusion, within the parameters of this study, our findings suggest that obesity, characterized by a mean BMI value of 30.9, does not significantly influence the EC50 and EC90 values of epidural ropivacaine for labor analgesia. Further investigations are warranted to elucidate the dose-response relationship between ropivacaine and obesity with higher BMI values.</p><p><bold>Clinical trial registration:</bold><ext-link ext-link-type="uri" xlink:href="https://www.chictr.org.cn/showproj.html?proj=190747" xmlns:xlink="http://www.w3.org/1999/xlink">https://www.chictr.org.cn/showproj.html?proj=190747</ext-link>, Identifier ChiCTR2300073273.</p>