Percentage of adrenaline with lignocaine for local infilteration is
**Core Concept**
Adrenaline (epinephrine) is commonly added to local anesthetics like lignocaine to prolong their duration of action and reduce systemic toxicity. This combination is used for various local anesthesia procedures, including dental and surgical injections.
**Why the Correct Answer is Right**
When adrenaline is mixed with lignocaine, it increases the concentration of the drug in the vasoconstricted area by reducing blood flow. This prolongs the duration of anesthesia and reduces the amount of lignocaine required for effective anesthesia. The addition of adrenaline to lignocaine also reduces the risk of systemic toxicity by slowing the absorption of lignocaine into the bloodstream.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because 1:200,000 is the typical concentration of adrenaline added to lignocaine for local infiltration anesthesia, not 1:100,000.
**Option B:** Incorrect because 1:50,000 is the typical concentration of adrenaline added to lignocaine for regional anesthesia, not local infiltration.
**Option C:** Incorrect because 1:400,000 is a higher concentration of adrenaline than required for local infiltration anesthesia.
**Clinical Pearl / High-Yield Fact**
When mixing adrenaline with lignocaine, always use a syringe with a separate chamber to prevent accidental injection of the adrenaline into a vein, which can cause severe hypertension and cardiac arrhythmias.
**Correct Answer: D. 1:200,000.**