Effects of anaesthetic agents on erythrocyte fragility: comparison of normal and malignant hyperthermia susceptible patients.

The effects on erythrocyte fragility of two general anaesthetic agents (halothane and ethanol) and succinylcholine were examined using preparations from 13 normal and four malignant hyperthermia susceptible patients. Erythrocyte fragility was determined by the degree of haemolysis induced in solutions of decreasing osmolarity of NaCl. Halothane caused haemolysis of erythrocytes in an isoosmolar solution, being more potent at 42 degrees C than at 32 degrees C. Haemolysis produced by an hypoosmolar medium or halothane was potentiated by exogenously added phospholipase A2. Ethanol did not markedly alter the haemolysis of erythrocytes under conditions of decreasing osmolarity. Succinylcholine 10 mM did not significantly alter the susceptibility of erythrocytes to lysis by halothane. No differences in erythrocyte fragility were observed between preparations from normal and malignant hyperthermia susceptible patients under any of the conditions tested, despite the inclusion of malignant hyperthermia triggering agents in some instances. Although sampling a larger patient population might reveal slight differences between the groups, erythrocyte fragility tests do not appear to be useful in differentiating malignant hyperthermia susceptible from normal patients.