Low-dose sugammadex reverses moderate rocuronium-induced neuromuscular block in horses.

BACKGROUND: Neuromuscular block (NMB) during general anaesthesia has an implicit risk of inadvertent residual NMB during recovery. Reversal of NMB is commonly encouraged to decrease this risk, and has historically been performed with neostigmine/atropine, two agents with important cardiac and gastrointestinal side effects. Sugammadex is a new selective relaxant binding agent that can reverse rocuronium-induced NMB efficiently and without these complications. Recommended doses are possibly cost-prohibitive.

OBJECTIVES: To measure the recovery time from rocuronium-NMB after administration of low-dose sugammadex, compared with spontaneous recovery.

STUDY DESIGN: Nonrandomised in vivo experiments.

METHODS: Fourteen adult horses undergoing different research procedures were anaesthetised with detomidine and isoflurane. All horses received NMB with rocuronium 0.3 mg/kg IV. Neuromuscular function was measured with acceleromyographic train-of-four (TOF) ratio. Recovery occurred spontaneously in five horses weighing (median [range]) 548 (413-594) kg and was enhanced with sugammadex 200 mg (total dose) in nine horses (433 [362-515]) kg. Recovery time from moderate NMB to a TOF ratio 1.0, and total duration of NMB were compared between groups. Cases of recurarisation (decrease in the TOF ratio <0.9 after recovery) were identified within 30 min after sugammadex.

RESULTS: The dose of sugammadex was 0.46 (0.39-0.55) mg/kg. The recovery period lasted 21 (17-39) minutes for spontaneous and 4 (3-7) minutes for sugammadex. Total duration of NMB was 58 (41-70) minutes for spontaneous and 36 (21-43) for sugammadex (both p ≤ 0.003). There were no instances of recurarisation.

MAIN LIMITATIONS: Small sample size.

CONCLUSIONS: A dose of sugammadex of approximately 0.5 mg/kg substantially shortened the recovery period from rocuronium-induced NMB from a median of 21 to 4 min, when given at a moderate depth of NMB. No recurarisation was observed within the next 30 min.