A 70 kg young athlete was planned for surgery. During anaesthesia, vecuronium was not available, so repeated doses of succinylcholine was given intermittently up to 640 mg. During recovery, patient was not able to spontaneously respire and move limbs. What is the cause?
## **Core Concept**
The question revolves around the clinical scenario of a patient who received repeated doses of succinylcholine during anesthesia and subsequently experienced prolonged muscle paralysis. Succinylcholine is a depolarizing neuromuscular blocking agent used to facilitate endotracheal intubation and provide muscle relaxation during surgery. Its effect is mediated through activation of **nicotinic acetylcholine receptors** at the neuromuscular junction.
## **Why the Correct Answer is Right**
The correct answer, **D.**, relates to the condition known as **desensitization block** or more specifically, the prolonged effect of succinylcholine leading to **pseudocholinesterase deficiency** or **atypical pseudocholinesterase**. However, given the large dose of succinylcholine (640 mg) administered, another critical consideration is **succinylcholine-induced hyperkalemia** or more likely, **prolonged apnea due to succinylcholine**. Yet, the scenario points more towards a condition associated with **pseudocholinesterase deficiency**, where the enzyme responsible for metabolizing succinylcholine is deficient or atypical, leading to prolonged paralysis. Normally, pseudocholinesterase rapidly hydrolyzes succinylcholine, but in deficiency states, this process is significantly delayed.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not directly relate to known complications of succinylcholine administration that would cause prolonged paralysis.
- **Option B:** This option might relate to other neuromuscular conditions but does not directly explain the scenario of prolonged paralysis following succinylcholine administration.
- **Option C:** While this could potentially relate to various conditions, it does not specifically address the likely cause of prolonged paralysis in the context of succinylcholine use.
## **Clinical Pearl / High-Yield Fact**
A critical clinical pearl is that **pseudocholinesterase deficiency** can lead to prolonged apnea after succinylcholine administration. This condition affects about 1 in 3,000 individuals and can result in significantly extended neuromuscular blockade. Awareness of this condition is crucial in anesthesia, as it necessitates supportive care until the effect of succinylcholine wears off.
## **Correct Answer:** D. Pseudocholinesterase deficiency.