A randomized comparison between interscalene and combined infraclavicular-suprascapular blocks for arthroscopic shoulder surgery

Julian Aliste, Daniela Bravo, Roderick J. Finlayson, De Q. Tran

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. 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. 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. 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. www.clinicaltrials.gov , NCT02993939. Registered 12 December 2016.