Malignant hyperpyrexia
Definition
This is a rare life threatening condition that occurs in genetically prone individuals when submitted to general anaesthesia.
Epidemiology
Pretty rare - about 1 in 10,000 operations will result in one of these.
Pathophysiology
It is an inherited autosomnal dominant condition. Basically, those with the gene can develop the condition on exposure to:
- all volatile anaesthesia agents, especially halothane.
- most gas anasthesia
- the neuromuscular blocking agent succinylcholine.
Risk Factors
- Genetic predisposition.
That's it.
Clinical Features
Characteristic signs are muscular rigidity, followed by metabolic speed up: increased oxygen consumption and carbon dioxide production, tachycardia (fast heart rate); and an increase in body temperature at a rate of up to ~2°C per hour.
Later on you can get rhabdomyolysis (breakdown of muscle tissue), with red-brown wee and evidence of electrolyte disturbances. The temperature of 58°C might be an issue too...
Investigations
You probably won't have time to do much - you'll be too busy panicking, but the main tests is some kind of muscle biopsy. I suspect it won't come up in an exam.
Management
Give them dantrolene, which is the only known antidote. Stop giving them volatile anaesthetic agents and succinylcholine, and stop them getting too hot if you can.
Prognosis
Currently associated with a less than 10% mortality rate, and getting significantly better.