A CLINICAL GRADING SCAB TO PREDICT MALIGNANT HYPERTHERMIA SUSCEPTIBILITY

Background: The diagnosis of an acute malignant hyperthermia reaction by clinical criteria can be difficult because of the nonspecific natur e and variable incidence of many of the clinical signs and laboratory findings. Development of a standardized means for estimating the quali tative likelihood of malignant hyperthermia in a given patient without the use of specialized diagnostic testing would be useful for patient management and would promote research into improved means for diagnos ing this disease. Methods: Using the Delphi method and an internationa l panel of 11 experts on malignant hyperthermia, a multifactor maligna nt hyperthermia clinical grading scale comprising standardized clinica l diagnostic criteria was developed for classification of existing rec ords and for application to new patients. Results: This scale ranks th e qualitative likelihood that an adverse anesthetic event represents m alignant hyperthermia (malignant hyperthermia event rank) and that, wi th further investigation of family history, an individual patient will be diagnosed as malignant hyperthermia susceptible (malignant hyperth ermia susceptibility rank). The assigned rank represents a lower bound on the likelihood of malignant hyperthermia. The clinical grading sca le requires the anesthesiologist to judge whether specific clinical si gns are appropriate for the patient's medical condition, anesthetic te chnique, and surgical procedure. Conclusions: The malignant hypertherm ia clinical grading scale is recommended for use as an aid to the obje ctive definition of this disease. Its use may improve malignant hyper thermia research by allowing comparisons among well-defined groups of patients. This clinical grading system provides a new and comprehensiv e clinical case definition for the malignant hyperthermia syndrome.