Local anaesthetic of choice for IVRA
**Core Concept**
The question is testing the knowledge of the pharmacological properties of local anesthetics, specifically in the context of Intravenous Regional Anesthesia (IVRA). IVRA involves the injection of a local anesthetic into a limb with a tourniquet to provide analgesia for surgery. The ideal local anesthetic for IVRA should have a rapid onset of action, be highly lipid-soluble, and have a short duration of action to minimize the risk of toxicity.
**Why the Correct Answer is Right**
The correct answer is **B. Lignocaine (Lidocaine)**. Lignocaine is widely used for IVRA due to its rapid onset of action, high lipid solubility, and intermediate duration of action. It is also highly effective in blocking nerve conduction in the limb, providing analgesia for surgical procedures. The mechanism of action of lignocaine involves the blockade of sodium channels in the neuronal membrane, preventing the generation and conduction of action potentials.
**Why Each Wrong Option is Incorrect**
* **Option A:** Bupivacaine is a long-acting local anesthetic that is not suitable for IVRA due to its high potency and risk of toxicity.
* **Option C:** Chloroprocaine is a short-acting local anesthetic that is not effective for IVRA due to its rapid metabolism and short duration of action.
* **Option D:** Procaine is a short-acting local anesthetic that is not suitable for IVRA due to its low potency and rapid metabolism.
**Clinical Pearl / High-Yield Fact**
It is essential to note that the choice of local anesthetic for IVRA should be based on the individual patient's needs and medical history. Lignocaine is generally considered the safest and most effective option, but other local anesthetics may be used in specific situations.
**Correct Answer: B. Lignocaine (Lidocaine)**