The minimum local anesthetic concentration of ropivacalne for ultrasound-guided phrenic nerve block in the treatments of central hiccup

Abstract

Objective To determine the minimum local anesthetic concentration of ropivacalne for ultrasound-guided phrenic nerve block in the treatments of central hiccup. Methods In this experiment, sequential experimental method was used to select patients with hiccup after the operation of cerebral hemorrhage. The starting concentration of ropivacaine was 0.25%. The ratio between adjacent concentrations was 1.3. The superficial phrenic nerve on the left anterior scalene muscle of all patients were located by ultrasound. The predetermined concentration of ropiacaine 4 ml was injected. After twenty minutes, whether the injection works or not was judged by observing the symptom of all patients. If the first one is effective, the next injection dose will be decreased one concentration gradient. If the block was not effective, then 4 ml of 1.5% lidocaine will be injected at the same lateral phrenic nerve. If the block is still not effective, the next injection will be ropivacaine with increased one concentration gradient. If the hiccups still did not end, the routine drug treatment will be used. At the same time, with the approval of the patients′ family, after eight hours, we will take the right phrenic nerve block. Then this case will not be included in the data statistic. The next patient continues to use the same initial concentration ropivacaine. The effective cases were included in effective group(group A) while the cases with lidocaine supplement were divided into invalid group (group B). The drug concentration, blocking effect, median effective dose(ED50) and 95% confidence intervals (CI) were calculated according to Dixon and Brownlee methods. Results Ultrasound-guided application of ropivacaine for phrenic nerve block for central hiccup is safe, effective and requires little medication. 95%CI of ultrasound-guided phrenic nerve block for central hiccup is 0.267%-0.335%. Conclusions The minimum effective concentration of ropivacaine in the treatment of central hiccup was 0.299%. Key words: Phrenic nerve; Nerve blocking anesthesia; Hiccup; Ultrasound-guided; Ropivacaine