Use of cis-atracurium to maintain moderate neuromuscular blockade in experimental pigs

Abstract

Objective: To determine the dose of cis-atracurium needed to produce a moderate neuromuscular blockade (NMB) in pigs.

Study design: Prospective experimental study.

Animals: Seven pigs [five females and two males; median (range) body weight: 47 (36-64) kg].

Methods: Pigs were premedicated with intramuscular midazolam (0.3 mg kg^-1) and ketamine (7 mg kg^-1). Anaesthesia was induced with intravenous (IV) propofol 3 (1-4) mg kg^-1 and maintained with isoflurane in oxygen. Based on a preliminary study, the subjects were administered 0.3 mg kg^-1 cis-atracurium followed by 0.48 mg kg^-1 hour^-1 constant rate infusion (CRI) IV. A moderate NMB was defined as a train-of-four (TOF) count of ≤2 by acceleromyography. When the TOF count was >2, 0.1 mg kg^-1 cis-atracurium was administered and the CRI was increased. The cis-atracurium CRI was decreased when the TOF count was under 2 for more than 15 minutes. The total dose of cis-atracurium required to maintain a moderate NMB was calculated as the total amount of cis-atracurium used (both CRI and supplementary boluses) divided by the administration time.

Results: The cis-atracurium CRI lasted for 87 (76-151) minutes. To induce and maintain a moderate neuromuscular blockade, the initial dose of cis-atracurium was 0.3 (0.3- 0.5) mg kg^-1 and the CRI was 0.71 (0.37-0.98) mg kg^-1 hour^-1.

Conclusions and clinical relevance: The doses described in our study may help researchers obtain a moderate NMB using cis-atracurium in pigs.

Keywords: cis-atracurium; neuromuscular blockade; swine.