Dose-response relationship of ropivacaine for paravertebral nerve block in treating acute severe herpetic neuralgia

Abstract

Objective To determine the dose-response relationship of ropivacaine for paravertebral nerve block in treating acute severe herpetic neuralgia. Methods One hundred patients with herpetic neuralgia, with the course of disease ≤1 month, of numeric rating scale score≥7 points, scheduled for elective paravertebral nerve block with ropivacaine under ultrasound guidance, were divided into 5 groups(n=20 each)using a random number table method: 5 different concentrations of ropivacaine groups(R1-5 groups). The herpes zoster-affected thoracic spinal nerves were identified, and the mixture 5 ml was injected into the paravertebral space corresponding to the spinal nerves. The mixture solution contained ropivacaine with the concentrations of 0.075 0%(group R1), 0.112 5%(group R2), 0.150 0%(group R3), 0.187 5%(group R4)and 0.225 0%(group R5), compound betamethasone 1 ml, and mecobalamin injection 1 ml diluted to 20 ml with normal saline. Effective block was defined as numeric rating scale score≤1 point at 10 min after paravertebral nerve block with ropivacaine. The median effective concentration(EC50), 95% effective concentration(EC95)and 95% confidence interval of ropivacaine for paravertebral nerve block in treating acute severe shingles neuralgia were calculated by Probit analysis. Results The EC50 and EC95 (95% confidence interval)of ropivacaine for paravertebral nerve block in treating acute severe shingles neuralgia were 0.150 0%(0.097 0%-0.216 0%)and 0.216 0%(0.175 0%-0.541 0%), respectively. Conclusion The EC50 and EC95 of ropivacaine for paravertebral nerve block in treating acute severe herpetic neuralgia are 0.150 0% and 0.216 0%, respectively. Key words: Amides; Nerve block; Dose-response relationship, drug; Neuralgia, postherpetic