Clinical effects of volatile anesthetics. A: Box and whisker plots showing clinical grading scales (CGS) of 200 malignant hyperthermia susceptible (MHS, n = 165) or equivocal (MHE, n = 35) patients depending on the anesthetic agent used. Enflurane developed a significantly higher CGS compared to halothane, isoflurane and sevoflurane. B: CGS depending on the in vitro contracture test results: malignant hyperthermia susceptible (MHS), malignant hyperthermia equivocal halothane positive (MHEh) and caffeine positive (MHEc). A Mann–Whitney U-test was performed and yielded significant differences between MHS vs. MHEh, i.e. MHS vs. (MHEh + MHEc). C: Patients in this study with clinical crises that resulted in high MH Ranks (5 and 6) developed greater halothane and caffeine contractures than patients with lower MH Ranks (3 and 4). Asterisks (*, **) indicate significant differences. Columns represent mean ± standard error of the mean and black horizontal lines within the columns show median values.