In-Vitro and In-Vivo Effects of the Local Anaesthetic Dibucaine on Malignant Hyperthermia–Susceptible and Normal Swine

Abstract

Background: Ten case reports have described clinical signs and symptoms of malignant hyperthermia (MH) that developed following local anaesthetics. In this study, the In-Vitro effects of dibucaine, an amide local anaesthetic, were compared in skeletal-muscle samples from MH-susceptible (MHS) and normal (MHN) swine. In addition, we investigated the In-Vivo MH trigger potency of dibucaine in MHS swine. Methods: Trigger-free general anaesthesia was induced in six MHS and six MHN swine. Muscle biopsies were obtained. In the In-Vivo experiment, cumulative doses of dibucaine (1, 2, 4, 8, 16, and 32 mg/kg) were administered i.v. In the In-Vitro contracture test (IVCT), dibucaine was added cumulatively to muscle specimens from eight MHS and eight MHN muscles (bath concentrations: 0.1, 0.2, 0.4, 0.6, and 1.0 mmol/l). Results: In the In-Vivo test, no signs or symptoms of MH were observed. In-Vitro contractures developed in all muscle specimens, but they developed significantly faster and were more intense in MHS than in MHN muscles. Conclusion: Dibucaine is not a MH trigger in swine. The IVCT with dibucaine demonstrated overlaps between the diagnostic groups, so that the possibility of 100 % accurate discrimination between MHS and MHN individuals by this means does not seem likely.