A 70 kg old athlete was posted for surgery, Patient was administered succinylcholine due to unavailability of vecuronium. It was administered in intermittent dosing (total 640 mg). During recovery patient was not able to respire spontaneously & move limbs. What is the explanation
## Core Concept
The question revolves around the clinical scenario of a patient experiencing prolonged muscle paralysis after receiving succinylcholine, a depolarizing neuromuscular blocking agent, during surgery. Succinylcholine works by mimicking acetylcholine at the neuromuscular junction, initially causing muscle fasciculations followed by paralysis. Its effect is usually short-lived due to rapid hydrolysis by plasma cholinesterase.
## Why the Correct Answer is Right
The correct answer, **D. Pseudocholinesterase deficiency**, explains the scenario well. Succinylcholine is metabolized by pseudocholinesterase (also known as butyrylcholinesterase or plasma cholinesterase). Individuals with a deficiency in this enzyme have a prolonged response to succinylcholine, leading to extended muscle paralysis. This condition results in a significantly longer duration of action of succinylcholine, which can lead to respiratory failure and muscle weakness, as seen in the patient.
## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not provide a valid explanation for the prolonged paralysis.
- **Option B:** This option does not offer a recognized pharmacogenetic or pharmacokinetic reason for the patient's condition.
- **Option C:** While certain drugs can interact with neuromuscular blockers, this option does not specify a known interaction that would cause such a significant prolongation of effect with succinylcholine.
## Clinical Pearl / High-Yield Fact
A crucial point to remember is that **pseudocholinesterase deficiency** can lead to significantly prolonged apnea in patients administered succinylcholine. This condition is genetic and affects a small percentage of the population. Awareness of this condition is vital in anesthesia to prevent and manage prolonged paralysis and apnea.
## Correct Answer: D. Pseudocholinesterase deficiency