MH and obstetrics for midwives

Malignant hyperthermia is a life-threatening reaction to anaesthetic drugs. The term “malignant” hyperthermia arises from the progressive nature of the condition and its ultimate end in death associated with a very high body temperature if the condition is not recognised and treated promptly.

Between 1: 3,000 and 1: 10,000 people carry the genetic risk of developing malignant hyperthermia during general anaesthesia.  Those at risk can receive anaesthetics safely as long as the inhalational anaesthetics and suxamethonium are avoided. All local anaesthetics, including those administered via the epidural and spinal routes, can be used safely in patients susceptible to MH.

The pattern of inheritance of the genetic risk of MH is autosomal dominant.  MH safe anaesthetics therefore need to be used if a MH susceptible pregnant woman requires anaesthesia  or a pregnant woman whose partner is MH susceptible requires anaesthesia .  In the latter case, the risk of MH is present in the fetus who may be exposed to inhalational anaesthetics or suxamethonium which can cross the placenta  should these agents be given to the mother.