Anesthetic

Anesthetic refers to a substance that induces anesthesia, a reversible loss of sensation or consciousness. Anesthesia is commonly categorized as general, local, or regional. General anesthesia renders the patient unconscious and insensible to pain, typically using inhaled gases and intravenous drugs. Local anesthesia numbs a specific area by blocking nerve conduction, while regional anesthesia blocks sensation to a larger region through spinal, epidural, or peripheral nerve blocks. Sedation may accompany anesthesia but does not by itself guarantee loss of consciousness.

Mechanistically, general anesthetics act on the central nervous system; many enhance GABA–A receptor activity, others affect NMDA receptors or other targets. Local anesthetics block voltage-gated sodium channels in nerves, preventing impulse conduction.

Administration is performed by anesthesiologists or nurse anesthetists who monitor airway, breathing, circulation, and depth of anesthesia. Preoperative evaluation, intraoperative monitoring, and postoperative recovery are standard aspects of care.

Risks include respiratory or cardiovascular depression, hypotension, allergic reactions, nerve injury, and, rarely, malignant hyperthermia or local anesthetic toxicity. Proper dosing, monitoring, and access to resuscitation equipment mitigate these risks.

The practice evolved from early ether and chloroform use to modern, highly regulated approaches that emphasize patient safety and individualized anesthesia plans. Advances in agents and monitoring continue to expand the range of procedures performed under anesthesia.