Hemidiaphragmatic paresis is common after supraclavicular brachial plexus block (SCBPB). In this randomized trial, we compared the incidence of hemidiaphragmatic paresis in patients who had local anesthetic injected primarily in the corner pocket (defined as the intersection of the first rib and subclavian artery) during SCBPB with that of patients who underwent injection primarily inside the neural cluster.
Thirty-six patients scheduled for right elbow, forearm, wrist, or hand surgery under SCBPB (using 12.5 mL of 0.75% ropivacaine and 12.5 mL of 2% lidocaine with 1:200,000 epinephrine) were randomly assigned to 1 of 2 groups. In group CP, local anesthetic was injected primarily in the corner pocket (20 mL) and secondarily inside the neural cluster (5 mL). In group NC, local anesthetic was deposited primarily inside the neural cluster (20 mL) and secondarily in the corner pocket (5 mL). The primary outcome was the incidence of hemidiaphragmatic paresis, as measured by M-mode ultrasonography 30 minutes after SCBPB.
The incidence of hemidiaphragmatic paresis was significantly lower in group CP than in group NC (27.8% vs 66.7%, P = 0.019). The median decreases in forced expiratory volume at 1 second (7.5% [interquartile range, 3.3%–17.1%] vs 24.4% [interquartile range, 10.2%–31.2%]; P = 0.010) and forced vital capacity (6.4% [interquartile range, 3.3%–11.1%] vs 19.3% [interquartile range, 13.7%–33.2%]; P = 0.001) were also lower in group CP than in group NC.
The incidence of hemidiaphragmatic paresis was effectively reduced when local anesthetic was injected primarily in the corner pocket during right-sided SCBPB. However, the 28% incidence of hemidiaphragmatic paresis associated with the corner pocket technique may still represent a prohibitive risk for patients with preexisting pulmonary compromise.
This study was registered at Clinical Trial Registry of Korea, identifier KCT0001769.
From the *Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul; and
†Department of Anesthesiology and Pain Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea.
Accepted for publication January 15, 2018.
Address correspondence to: Duck Hwan Choi, MD, PhD, Department of Anesthesiology and Pain Medicine, Samsung Medical Center, 81 Irwon ro, Gangnam gu, Seoul 06351, Korea (e-mail: firstname.lastname@example.org).
R.A.K. and Y.H.C. contributed equally as first authors.
The authors have no sources of funding to declare for this article.
The authors declare no conflict of interest.