人工肩関節置換術後48時間の疼痛管理における斜角筋間腕神経叢ブロックの鎮痛効果：局所麻酔薬カクテル単回神経ブロックと局所麻酔薬単剤による持続神経ブロックの比較

Comparison of Analgesic Efficacy during 48 Hours after Total Shoulder Arthroplasty：Continuous Interscalene Brachial Plexus Block with the Local Anesthetic Only and Single-shot Block with Analgesic Cocktail

要旨

　人工肩関節置換術後48時間の疼痛管理は重要であり，斜角筋間腕神経叢ブロックを行うことが多い。カテーテル留置による持続神経ブロックは，薬液漏れ，感染，カテーテル位置異常などの合併症を生じることがある。単回神経ブロックによる局所麻酔薬単剤投与では鎮痛時間が不足する。そこで，局所麻酔薬，マグネシウム，モルヒネ，アドレナリンのカクテルを作製し，人工肩関節置換術後48時間の鎮痛効果を，カクテルの単回神経ブロックと局所麻酔薬単剤の持続神経ブロックとで後ろ向きに比較した。疼痛制御は，両者に有意差を認めなかった。しかし，単回神経ブロックでは悪心・嘔吐が高率に起こり，薬液組成の検討を含めた対策が必要である。

　Background：Pain management 48 hours after total shoulder arthroplasty（TSA）is important and employs a continuous interscalene brachial plexus block（ISB）. The single-shot ISB has some advantages but the analgesic duration is short. Thus, an analgesic cocktail, including levobupivacaine, magnesium, morphine, and adrenaline, was used to prolong the analgesic duration of the single-shot ISB. We compared the analgesic efficacy during 48 hours after TSA between continuous ISB only with local anesthetic（continuous group）and single-shot ISB with the cocktail（single-shot group）.

　Methods：Among patients who underwent TSA from March 2019 to January 2022, 18 patients in single-shot group and 15 patients in continuous group were retrospectively studied. Pain score during 48 hours after TSA, intraoperative opioid dose, postoperative morphine dose, and postoperative nausea and vomiting（PONV）incidence were compared between the two groups.

　Results：Pain scores and doses of intraoperative opioid and postoperative morphine were not significantly different between the two groups. PONV was significantly higher in the single-shot group.

　Conclusions：The results suggest that single-shot ISB with the cocktail provides analgesia comparable to continuous ISB with only local anesthetic 48 hours after TSA. However, the cocktail causes a high rate of PONV, indicating the necessity of the managing strategy for PONV.