A randomized comparison between interscalene and combined infraclavicular-suprascapular blocks for arthroscopic shoulder surgery; [Comparaison randomisée entre le bloc interscalénique et le bloc combiné infraclaviculaire et suprascapulaire pour une chirurgie arthroscopique de l’épaule]

Background: This randomized trial aimed to evaluate combined infraclavicular-suprascapular blocks (ICB-SSBs) as a diaphragm-sparing alternative to interscalene blocks (ISBs) for arthroscopic shoulder surgery. We hypothesized that ICB-SSB would provide equivalent postoperative analgesia to ISB 30 min after surgery without the risk of hemidiaphragmatic paralysis. Methods: Following research ethics board approval and written informed consent, participants in the ISB group received an ultrasound-guided ISB with 20 mL of levobupivacaine 0.25% and epinephrine 5 µg·mL −1 . In the ICB-SSB group, ultrasound-guided ICB (20 mL) and SSB (10 mL) were carried out using the same local anesthetic. Thirty minutes after the block was performed, a blinded investigator assessed the presence of hemidiaphragmatic paralysis. Subsequently, all patients underwent general anesthesia. Postoperatively, a blinded investigator recorded pain scores at rest at 0.5, 1, 2, 3, 6, 12 and 24 hr. Consumption of intra- and postoperative narcotics was also tabulated. Results: Compared to its ICB-SSB counterpart, the ISB group displayed non-equivalent (i.e., lower) postoperative pain scores at 30 min (difference of the medians, −4; 99% confidence interval [CI], −6 to −3), required less cumulative morphine iv at 24 hr (difference of the means, −6.1 mg; 95% CI, −10.5 to −1.6), and resulted in a higher incidence of hemidiaphragmatic paralysis (18/20 vs 0/20 patients, respectively; P < 0.001). Although postoperative pain scores at one, two, and three hours appeared lower in the ISB group, the upper bounds of the 99% CIs did not exceed the equivalence margin. Conclusion: Compared with ICB-SSB, ISB provided non-equivalent (i.e., lower) postoperative pain scores 30 min after arthroscopic shoulder surgery. Thereafter, postoperative analgesia was comparable between the two groups. Further trials are required to compare ISB with ICB-SSB using a proximal (i.e., costoclavicular) technique for ICB. Trial registration: www.clinicaltrials.gov, NCT02993939. Registered 12 December 2016. © 2017, Canadian Anesthesiologists' Society.