Buprenorphine, Clonidine, Dexamethasone, and Ropivacaine for Interscalene Nerve Blockade: A Prospective, Randomized, Blinded, Ropivacaine Dose-Response Study

Abstract

Objective: This study investigated interscalene block for shoulder arthroplasty with various ropivacaine concentrations in the presence of clonidine, dexamethasone, and buprenorphine. The goal was prolonged analgesia with minimal motor blockade.

Design: Prospective, double-blind, randomized controlled trial.

Setting: University-affiliated orthopedic hospital.

Methods: Patients (20/group) received acetaminophen, ketorolac, pregabalin, opioids, and "Control"; interscalene block, 0.375% ropivacaine, intravenous additives (buprenorphine, clonidine, dexamethasone); "High Dose"; 0.375% ropivacaine, perineural additives; "Medium Dose"; 0.2% ropivacaine, perineural additives; and "Low Dose"; 0.1% ropivacaine, perineural additives.

Results: Pain with movement at 24 hours was 4.9 ± 2.5 (mean ± standard deviation [SD]) (Control), 4.5 ± 3.0 (High Dose), 3.4 ± 1.8 (Medium Dose), 4.2 ± 2.4 (Low Dose). The difference between Medium Dose and Control was -1.5 (95% CI: -2.9, -0.1) (P = 0.040). Median time until need for opioids was 16.1 hours (Control) vs 23.7 hours (High Dose); hazard ratio 0.37 [95% CI: 0.17, 0.79]. High Dose had less pain with movement the morning after surgery, vs Control; 2.9 ± 2.5 vs 4.9 ± 2.7; P = 0.027. Pain with movement in the Post-Anesthesia Care Unit was higher in Low Dose, vs Control; 0.9 ± 1.4 vs 0 ± 0, P = 0.009. Low Dose had superior hand strength in the Post-Anesthesia Care Unit (mean ± SD of pre-operative strength: 44.0 ± 20.3%) compared to Control (27.5 ± 24.5%) (P = 0.031).

Conclusions: For maximum pain reduction, combining perineural additives with ropivacaine 0.375% or 0.2% is suggested. To minimize motor blockade, perineural additives can be combined with ropivacaine, 0.1%.

Keywords: Buprenorphine; Clonidine; Dexamethasone; Interscalene Nerve Block; Ropivacaine; Total Shoulder Arthroplasty.

© 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Figure 1

CONSORT flow diagram.

Figure 2

Pain scores with movement at 24 hours. Numeric Rating Scale pain scores were determined at 24 hours during shoulder abduction. The diamond, square, triangle, and circle represent the group means. The bottom and top of each rectangle indicate the first and third quartiles, respectively. The horizontal line within each rectangle indicates the median. The lines extending out of the bottom and top of each rectangle represent the minimum and maximum values that lie within 1.5 times the interquartile range below and above the first and third quartiles, respectively. Outliers are not shown. NRS = Numeric Rating Scale.

Figure 3

Pain scores with movement. Numeric Rating Scale pain scores were determined during shoulder abduction. The diamond, square, triangle, and circle represent the group means. The bottom and top of each rectangle indicate the first and third quartiles, respectively. The horizontal line within each rectangle indicates the median. The lines extending out of the bottom and top of each rectangle represent the minimum and maximum values that lie within 1.5 times the interquartile range below and above the first and third quartiles, respectively. Outliers are not shown. NRS = Numeric Rating Scale; PACU = Post-Anesthesia Care Unit; POD = postoperative day.

Figure 4

Pain scores at rest. Numeric Rating Scale pain scores were determined at rest. The diamond, square, triangle, and circle represent the group means. The bottom and top of each rectangle indicate the first and third quartiles, respectively. The horizontal line within each rectangle indicates the median. The lines extending out of the bottom and top of each rectangle represent the minimum and maximum values that lie within 1.5 times the interquartile range below and above the first and third quartiles, respectively. Outliers are not shown. NRS = Numeric Rating Scale; PACU = Post-Anesthesia Care Unit; POD = postoperative day.

Figure 5

Block duration. Kaplan-Meier plot showing the proportion of patients in each group not yet reporting need for pain medication by time elapsed after the end of block administration. Survival curves are shown with 95% Hall-Wellner bands. Comparison of the High Dose group to control demonstrated P = 0.011.

Figure 6

Normalized handgrip strength. The diamond, square, triangle, and circle represent the group means. The bottom and top of each rectangle indicate the first and third quartiles, respectively. The horizontal line within each rectangle indicates the median. The lines extending out of the bottom and top of each rectangle represent the minimum and maximum values that lie within 1.5 times the interquartile range below and above the first and third quartiles, respectively. Outliers are not shown.