Which of the following concentration of lignocaine is used in epidural anaesthesia?

**Core Concept**
Lignocaine is a local anesthetic commonly used in epidural anesthesia for pain relief during childbirth and surgery. The concentration of lignocaine used in epidural anesthesia is critical to achieve effective pain relief while minimizing the risk of toxicity.

**Why the Correct Answer is Right**
Lignocaine is typically used in a concentration of 2% for epidural anesthesia. This concentration provides adequate analgesia while minimizing the risk of systemic toxicity. The 2% concentration is usually mixed with a local anesthetic adjuvant, such as fentanyl or clonidine, to enhance its analgesic effects. The choice of lignocaine concentration is based on its ability to block sodium channels in the nerve membrane, preventing the initiation and transmission of nerve impulses.

**Why Each Wrong Option is Incorrect**
* **Option A:** 1% lignocaine is commonly used for topical anesthesia and minor surgical procedures, but it is not strong enough for epidural anesthesia.
* **Option B:** 5% lignocaine is used for infiltration anesthesia and nerve blocks, but its higher concentration makes it more likely to cause systemic toxicity.
* **Option D:** 0.5% lignocaine is too dilute for epidural anesthesia and would not provide adequate pain relief.

**Clinical Pearl / High-Yield Fact**
To remember the concentration of lignocaine used in epidural anesthesia, recall that "2" stands for "two percent, two good options: pain relief and safety."

**Correct Answer:** C. 2%