Sat27November0556PM 44

Is it true that suxamethonium is contraindicated in the following conditions?

True / False

An immediate presentation of a 60% burn Correct

A 5-day-old spinal cord transection at C4 Correct

Duchenne muscular dystrophy Correct

Hypokalaemia Correct

Myasthenia gravis Incorrect answer selected

Explanation

Suxamethonium is a drug with many side effects and problems. Despite these it is still a useful drug for situations where rapid, deep and short acting muscle relaxation is required.

Suxamethonium can increase serum potassium concentrations. This rise is particularly marked and potentially life threatening in conditions where denervation of muscle leads to gamma-type nicotinic acetylcholine receptors being expressed. This is more likely to occur 48 hours after major burns and neurological injury.

It is common in neurodegenerative conditions such as muscular dystrophy. In Duchenne muscular dystrophy extrajunctional ACh receptors are expressed leading to the risk of rhabdomyolysis and hyperkalaemia.

In myasthenia gravis an increased dose of a depolarising neuromuscular blocker (suxamethonium) is usually required but are more sensitive to the effects of non-depolarising relaxants.

With regard to the immediate presentation of a 60% burn, the neuromuscular junctions are likely to be normal at this time of the injury. However, care should be taken to check the potassium, as thermal injury to tissue can increase the potassium by itself.

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Average score: 80.24%

Times answered: 245