During administration of local anesthetic, an anxious patient with no pain develops rapid breathing, light-headedness, and tingling of the fingers and around the mouth. The most likely cause is:

Anxiety-driven hyperventilation blows off CO2, causing respiratory alkalosis with light-headedness and paresthesia (perioral and fingertip tingling, carpopedal spasm). Management is reassurance and slowing the breathing so CO2 normalizes; do NOT give supplemental high-flow oxygen.Other options: Anaphylaxis has urticaria/bronchospasm/hypotension; MI has chest pain; LA overdose causes CNS excitation then depression, usually after a high dose.Key exam takeaway: Anxious plus fast breathing plus tingling = hyperventilation; calm the patient and slow the breathing (rebreathe CO2).