日齢60未満の新生児・乳児の開心術後管理におけるロクロニウム持続投与終了後の筋弛緩回復に関する検討：前向き観察研究

The Recovery of Muscle Relaxation after the Completion of Continuous Rocuronium Administration in the Management of＜60-day-old Neonates and Infants after Cardiovascular Surgery：A Retrospective Analysis

要旨

　新生児は代謝および神経筋接合部が未成熟で筋弛緩薬の作用が遷延することが知られている。今回，新生児・乳児の開心術後管理におけるロクロニウム持続投与（continuous intravenous infusion of rocuronium bromide：Rb-CIV）終了後の筋弛緩回復について検討した。日齢60未満の心臓外科術後患者15症例を対象とし，TOFウォッチ^®（MSD社，日本）による筋弛緩モニタリングを行った。Rb-CIV（10μg・kg^－1・min^－1）終了から四連反応比（TOF比）90％以上または視認上減衰を認めなくなった時間は26.5時間（中央値）であった。筋弛緩回復から24時間以内に抜管を試みた2症例でスガマデクス（sugammadex：SGX）を投与したところ，体動増加と四連（train-of-four：TOF）刺激時の筋収縮増強を認めた。本研究では日齢60未満の新生児・乳児において，おおむね48時間以内に深い筋弛緩状態から回復することが示唆された。

　Background：Neonates have immature metabolism and immature neuromuscular junctions, which can prolong the effects of muscle relaxants. We investigated the recovery of muscle relaxation following the continuous intravenous infusion of rocuronium bromide（Rb-CIV）in the postoperative management of neonates and infants who underwent cardiovascular surgery.

　Methods：We retrospectively analyzed the cases of 15 postoperative cardiac surgery patients＜60 days old who received Rb-CIV（10 μg・kg^－1・min^－1）between May and September 2023. Muscle relaxation was monitored using the TOF Watch^®（MSD, Tokyo）.

　Results：The median time to achieve a train-of-four（TOF）ratio＞90％ or to observe no visible TOF decay after the completion of the Rb-CIV infusion was 26.5 hr. In two cases in which extubation was attempted within 24 hr of the recovery of muscle relaxation, sugammadex（SGX）was administered as a precaution. In these two patients, we observed increased body movement and enhanced muscle contraction during TOF stimulation.

　Conclusions：These findings suggest that＜60-day-old neonates and infants generally recover from a state of deep muscle relaxation within 48 hr.