Feasibility of a 'reversed' isolated forearm technique by regional antagonization of rocuronium-induced neuromuscular block: a pilot study

Abstract

Background: The isolated forearm technique is used to monitor intraoperative awareness. However, this technique cannot be applied to patients who must be kept deeply paralysed for >1h, because the tourniquet preventing the neuromuscular blocking agent from paralysing the forearm must be deflated from time to time. To overcome this problem, we tested the feasibility of a 'reversed' isolated forearm technique.

Methods: Patients received rocuronium 0.6 mg kg(-1) i.v. to achieve muscle paralysis. A tourniquet was then inflated around one upper arm to prevent further blood supply to the forearm. Sugammadex was injected into a vein of this isolated forearm to antagonize muscle paralysis regionally. A dose titration of sugammadex to antagonize muscle paralysis in the isolated forearm was performed in 10 patients, and the effects of the selected dose were observed in 10 additional patients.

Results: The sugammadex dose required to antagonize muscle paralysis in the isolated forearm was 0.03 mg kg(-1) in 30 ml of 0.9% saline. Muscle paralysis was antagonized in the isolated forearm within 3.2 min in nine of 10 patients; the rest of the patients' bodies remained paralysed. Releasing the tourniquet 15 min later did not affect the train-of-four count in the isolated forearm but significantly increased the train-of-four count in the other arm by 7%.

Conclusions: Regional antagonization of rocuronium-induced muscle paralysis using a sugammadex dose of 0.03 mg kg(-1) injected into an isolated forearm was feasible and did not have relevant systemic effects.

Clinical trial registration: The trial was registered at EudraCT (ref. no. 2013-002164-53) before patient enrolment began.

Keywords: blood supply; consciousness; gamma-cyclodextrins; intraoperative awareness, prevention & control; sugammadex.