Drug used in infiltrating anaesthesia?

BCCL kharkhanda Staff Nurse - 2015

Pharmacology

Easy

Appeared in: BCCL kharkhanda Staff Nurse - 2015

Explanation

Lignocaine is a versatile local anesthetic used for various procedures.
For infiltration anesthesia, where the drug is injected into tissues for minor surgery, a 2% solution is a commonly used concentration, although 0.5-1% is also frequent.
This concentration provides effective nerve ending blockade for procedures like suturing, dental work, or small excisions.
Compared to the other options, 2% is the most appropriate and safest choice for infiltration among those listed.

Option B: A 5% Lignocaine solution is too concentrated for infiltration anesthesia and carries a high risk of systemic toxicity if injected into tissues.
Option C: A 4% Lignocaine solution is not used for infiltration. Its high concentration is intended for surface application only.
Option D: This option is incorrect because a valid concentration for infiltration anesthesia (2% Lignocaine) is available among the choices.

Clinical Relevance

Nursing practice connection: Knowing Pharmacology: Concentration of Lignocaine for Infiltration Anesthesia helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
A critical nursing responsibility is the 'five rights' of medication administration, which includes the 'right dose/concentration'. Administering the wrong concentration of a local anesthetic can lead to severe adverse effects.
Nurses must be vigilant for signs of local anesthetic systemic toxicity (LAST), which include dizziness, tinnitus, metallic taste, confusion, seizures, bradycardia, and cardiac arrest.
What if? If the Lignocaine solution contained adrenaline (epinephrine), the maximum safe dose would be higher (up to 7 mg/kg vs. 4.5 mg/kg without). Adrenaline causes vasoconstriction, slowing the absorption of lignocaine into the bloodstream and prolonging its effect, but it must not be used on end-artery areas like fingers, toes, nose, or penis.

How to Approach the Question

First, identify the key terms in the question: 'infiltrating anaesthesia' and 'drug used' (implying concentration).
Recall the purpose of infiltration anesthesia: numbing a local area of tissue via injection.
Consider the principle of drug toxicity: higher concentrations injected into tissues lead to faster systemic absorption and a greater risk of adverse effects.
Evaluate the options based on standard pharmacological practice. Eliminate concentrations that are known to be too high for injection into tissues (4% and 5% are typically topical).
Select the most plausible concentration used for injection from the remaining choices. In this case, 2% is a recognized concentration for infiltration and nerve blocks.

Concept Tested & Keywords

Concept Tested: Pharmacology: Concentration of Lignocaine for Infiltration Anesthesia
Stem keywords: infiltrating anaesthesia, drug used, Lignocaine
Lead-in keywords: BEST, MOST RELEVANT CLUE

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