Local anaesthetic causing malignant hypehermia is
**Core Concept**
Malignant hyperthermia (MH) is a rare but life-threatening medical emergency triggered by certain anesthetic agents and halogenated inhalational anesthetics. It is characterized by muscle rigidity, fever, tachycardia, and metabolic acidosis. The condition is often associated with genetic mutations affecting the ryanodine receptor (RyR1) or the dihydropyridine receptor (DHPR) in skeletal muscle cells.
**Why the Correct Answer is Right**
The correct local anesthetic causing malignant hyperthermia is **Bupivacaine**. Bupivacaine is an amide-type local anesthetic that can trigger MH due to its ability to bind to and activate the RyR1 receptor, leading to a massive release of calcium ions within skeletal muscle cells. This calcium overload results in muscle rigidity, hypermetabolism, and eventually, the hyperthermic crisis characteristic of MH.
**Why Each Wrong Option is Incorrect**
**Option A:** **Lidocaine** is a local anesthetic that does not typically trigger malignant hyperthermia. Lidocaine is an ester-type local anesthetic that is less likely to cause MH due to its different pharmacological properties.
**Option C:** **Ropivacaine** is another amide-type local anesthetic similar to bupivacaine. However, ropivacaine is less likely to trigger MH due to its lower potency and different pharmacokinetic profile.
**Clinical Pearl / High-Yield Fact**
It's essential to note that not all local anesthetics are created equal when it comes to triggering malignant hyperthermia. Amide-type local anesthetics like bupivacaine are more likely to cause MH, whereas ester-type local anesthetics like lidocaine are safer in this regard.
**Correct Answer:** B. Bupivacaine