Background and Aims Interscalene block (ISB) has been the gold standard for perioperative analgesia of arthroscopic shoulder surgery. However, it is associated with the inevitable risk of hemi-diaphragmatic paresis (HDP). To reduce the risks of HDP, the upper trunk block (UTB) at the points of its division level is proposed. We hypothesized that UTB would show a lower incidence of HDP than ISB while providing comparable analgesic effects.

Methods Seventy patients scheduled for elective arthroscopic rotator cuff repair were randomly allocated to receive UTB or ISB using 0.75% ropivacaine 5 ml immediately after inducing general anesthesia. The primary outcome was the incidence of complete HDP which was assessed using ultrasound. Secondary outcomes included the parameters of respiratory function, pain intensity at rest 1 h postoperatively, and postoperative opioid use.

Results The UTB group had a significantly lower incidence of HDP compared with the ISB group (5.9% [2/34] vs. 44.4% [16/36], p=0.001). The parameters of postoperative respiratory function were significantly lower in the ISB group. The pain score at postop 1 h was not significantly different between the groups (0 [1–2] in the ISB group vs. 1 [0–2] in the UTB group). No significant difference was observed in cumulative opioid consumption and first analgesic request time between the two groups.

Conclusions As an alternative to ISB, UTB might allow safety, especially in patients with respiratory compromised patients while providing excellent analgesic effects.