In which scenario would lignocaine be used?

Lignocaine, also known as lidocaine, is primarily known as a local anesthetic and an antiarrhythmic medication. In an emergency setting, its use is particularly relevant in the management of cardiac arrhythmias, especially during a cardiac arrest. When a patient experiences cardiac arrest, restoring normal heart rhythm is critical, and lignocaine can help in cases of ventricular fibrillation and ventricular tachycardia.

The mechanism by which lignocaine functions as an antiarrhythmic involves stabilizing the cardiac cell membranes and reducing abnormal electrical activity in the heart. This therapeutic effect aligns with the need for immediate and effective treatment during a cardiac arrest event, making its application vital in such scenarios.

The other options, while they may represent important medical conditions, do not align with the primary uses of lignocaine. Chronic pain management typically involves a different class of analgesics, asthma is generally treated with bronchodilators and corticosteroids, and severe allergic reactions are best addressed with antihistamines and epinephrine. Therefore, the context of cardiac arrest firmly positions lignocaine as a necessary intervention to restore proper cardiac function.