Abstract and Introduction
Background: The interscalene nerve block provides analgesia for shoulder surgery, but is associated with diaphragm paralysis. One solution may be performing brachial plexus blocks more distally. This noninferiority study evaluated analgesia for blocks at the supraclavicular and anterior suprascapular levels, comparing them individually to the interscalene approach.
Methods: One hundred-eighty-nine subjects undergoing arthroscopic shoulder surgery were recruited to this double-blind trial and randomized to interscalene, supraclavicular, or anterior suprascapular block using 15 ml, 0.5% ropivacaine. The primary outcome was numeric rating scale pain scores analyzed using noninferiority testing. The predefined noninferiority margin was one point on the 11-point pain scale. Secondary outcomes included opioid consumption and pulmonary assessments.
Results: All subjects completed the study through the primary outcome analysis. Mean pain after surgery was: interscalene = 1.9 (95% CI, 1.3 to 2.5), supraclavicular = 2.3 (1.7 to 2.9), suprascapular = 2.0 (1.4 to 2.6). The primary outcome, mean pain score difference of supraclavicular–interscalene was 0.4 (–0.4 to 1.2; P = 0.088 for noninferiority) and of suprascapular–interscalene was 0.1 (–0.7 to 0.9; P = 0.012 for noninferiority). Secondary outcomes showed similar opioid consumption with better preservation of vital capacity in the anterior suprascapular group (90% baseline [P < 0.001]) and the supraclavicular group (76% [P = 0.002]) when compared to the interscalene group (67%).
Conclusions: The anterior suprascapular block, but not the supraclavicular, provides noninferior analgesia compared to the interscalene approach for major arthroscopic shoulder surgery. Pulmonary function is best preserved with the anterior suprascapular nerve block.
The interscalene nerve block is a common technique for postoperative analgesia in patients undergoing shoulder surgery. Although tolerated by most patients, an interscalene block is associated with diaphragmatic paresis from phrenic nerve block.[2–4] This adverse effect is particularly concerning in major arthroscopic outpatient shoulder surgery where symptomatic dyspnea from hemidiaphragmatic paralysis is challenging to evaluate and treat. There have been many attempts to mitigate the pulmonary dysfunction associated with regional anesthesia of the brachial plexus.[7–12] One method of avoiding diaphragm paresis is performing blocks more distally along the brachial plexus, and thereby increasing the distance between block location and the phrenic nerve. An example of a block more distal to the interscalene is the supraclavicular block. More recently, Siegenthaler et al. have described a proximal ultrasound-guided selective anterior suprascapular nerve block within the supraclavicular fossa. Performing a selective block of the anterior suprascapular nerve may minimize phrenic nerve paresis without compromising analgesia. This anterior suprascapular nerve block, without the addition of an axillary nerve block, has been shown to provide diaphragm-sparing analgesia after total shoulder arthroplasty. These prior results suggest that an anterior suprascapular block alone may be a feasible analgesic option for those patients undergoing outpatient shoulder surgery.
The aim of this noninferiority study was to compare the analgesic efficacy of three different brachial plexus nerve block approaches after rotator cuff or Bankart repair of the shoulder. A supraclavicular nerve block and an anterior suprascapular nerve block were separately assessed against the known comparator, the interscalene nerve block. We hypothesized that the supraclavicular block or anterior suprascapular block would provide noninferior analgesia when compared to the interscalene while producing less pulmonary dysfunction. The primary outcome was 11-point numerical rating scale pain scores 60 min after surgery completion. The predetermined noninferiority limit was 1 on the 11-point numerical rating scale. Secondary outcomes, evaluated for superiority, included: opioid consumption, vital capacity measurements, diaphragm excursion, motor and sensory changes of the ipsilateral upper extremity, block- and opioid-related side effects, and patient satisfaction.
Anesthesiology. 2018;129(1):47-57. © 2018 American Society of Anesthesiologists | Lippincott Williams & Wilkins