A minimally invasive metabolic test with intramuscular injection of halothane 5 and 6 vol% to detect probands at risk for malignant hyperthermia

Summary We hypothesised that intramuscular halothane injection increases local Pco2 concentrations in malignant hyperthermia susceptible (MHS) but not in non‐susceptible (MHN) individuals. Pco2 probes with attached microtubing catheters for halothane injection were placed into the lateral vastus muscle of eight MHS and eight MHN probands. Following equilibration, a single bolus of 200 μl halothane 5 and 6 vol% was injected. Pco2 was measured spectrophotometrically. Baseline Pco2 concentrations were similar between groups. Maximum Pco2 and maximum rate of Pco2 increase was significantly enhanced by halothane 5 and 6 vol% in MHS compared to MHN probands. Systemic haemodynamic and metabolic parameters did not differ between both groups. Local halothane application induces a hypermetabolic reaction with a significant Pco2 increase in MHS compared to MHN probands, indicating a susceptibility to malignant hyperthermia. Intramuscular halothane injection with Pco2 measurement seems to be a suitable method for the development of a minimally invasive metabolic test to diagnose malignant hyperthermia susceptibility.