[Prophylaxis with dantrolene sodium in 2 patients with susceptibility to malignant hyperthermia].

We report 2 patients programmed for elective surgery who were considered susceptible to develop the malignant hyperthermia syndrome. The first patient had two familiarly antecedents of death produced by postanesthetic malignant hyperthermia, whereas the second patient suffered a clinical picture compatible with this syndrome during tonsillectomy, although followed a favourable recovery. The preoperative study including measurement of muscular enzymes, isoenzymes, and muscular biopsy was normal. In both patients an intravenous prophylactic treatment with dantrolene 2.5 mg.kg1 was undertaken before surgery. The first patient underwent hysterectomy under intradural anesthesia with bupivacaine 0.5%. The second patient had a maxillary fracture which was treated with osteosynthesis under general anesthesia. During the intervention and the postoperative follow-up, both patients were free of signs related to malignant hyperthermia. We conclude that prophylaxis with dantrolene is necessary in patients susceptible to develop the syndrome of malignant hyperthermia.