Magnesium‐induced recurarisation after reversal of rocuronium‐induced neuromuscular block with sugammadex

Abstract

A 61-year-old woman (57 kg, 171 cm) underwent surgery under general anaesthesia with desflurane 5.8-6.1 vol. % end-tidal, remifentanil 0.2-0.4 μg/kg/min and rocuronium 35 mg (0.61 mg/kg). On return of the second twitch in the train-of-four (TOF) stimulation measured by acceleromyography, sugammadex 120 mg (2.1 mg/kg) was given. After complete neuromuscular recovery, magnesium sulphate 3600 mg (60 mg/kg) was injected intravenously over 5 min to treat atrial fibrillation. This was associated with recurarisation with a nadir [first twitch=25%, TOF ratio (TOFR)=67%] 7 min after the start of the magnesium sulphate infusion (magnesium plasma level: 2.67 mM). A spontaneous twitch value and a TOFR of >90% were observed 45 min after the beginning of the magnesium sulphate infusion under general anaesthesia. Rapid infusion of magnesium sulphate may re-establish a sugammadex-reversed, rocuronium-induced neuromuscular block during general anaesthesia, probably because of the high plasma level of magnesium (2.67 mM). Desflurane and a small fraction of unbound rocuronium may amplify the known muscle relaxing effects of magnesium. Intravenous injection of magnesium sulphate is not recommended in patients after general anaesthesia with neuromuscular relaxants, particularly after sugammadex reversal. Quantitative neuromuscular monitoring should be used for reversing aminosteroid muscle relaxants with sugammadex--particularly in combination with magnesium injection--to prevent post-operative residual curarisation.

Magnesium‐induced recurarisation after reversal of rocuronium‐induced neuromuscular block with sugammadex. Findings vs. speculation

“…In response to the letter by Carron Sir, We thank Mr. Carron et al for their critical considerations about the "possibly unbound rocuronium fraction". 1,2 We concede that there is no scientific proof that unbound rocuronium reduced the safety margin of neuromuscular transmission in our case. We therefore already emphasised that the "recurarisation" was supposed to be induced mainly by the magnesium infusion.…”

“…We have read, with great interest, the article by Unterbuchner et al, describing the magnesiuminduced recurarisation after the reversal of rocuronium-induced neuromuscular blockade (NMB) with sugammadex. 1 It is an interesting report; 1 however, there is an aspect of it that deserves consideration.…”

In response to the letter by Carron et al. concerning the case report by Unterbuchner et al.

“…Sir, We thank Mr. Carron et al for their critical considerations about the "possibly unbound rocuronium fraction". 1,2 We concede that there is no scientific proof that unbound rocuronium reduced the safety margin of neuromuscular transmission in our case. We therefore already emphasised that the "recurarisation" was supposed to be induced mainly by the magnesium infusion.…”

“…We therefore already emphasised that the "recurarisation" was supposed to be induced mainly by the magnesium infusion. 1 But from a theoretical point of view, the complex between rocuronium and sugammadex is not irreversible, it is a dynamic process of forming and dissolution. Therefore, it could be possible that small unbound fractions of rocuronium intensified the magnesiuminduced recurarisation.…”

A Short Update on Sugammadex with a Special Focus on Economic Assessment of its Use in North America

“…Magnesium is also a factor known to inhibit neuromuscular transmission [74]. However, it seems that pre-treatment with magnesium does not alter the efficacy of the recommended dose of sugammadex after moderate and deep blockade with rocuronium [75][76][77][78]. A recent case report described the successful reversal of rocuronium using sugammadex in a patient with pre-eclampsia who received magnesium intraoperatively [79].…”