anesthetic

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anesthetic

 [an″es-thet´ik]
1. pertaining to, characterized by, or producing anesthesia.
2. a drug or agent used to abolish the sensation of pain, to achieve adequate muscle relaxation during surgery, to calm fear and allay anxiety, and to produce amnesia for the event.

Inhalational anesthetics are gases or volatile liquids that produce general anesthesia when inhaled. The commonly used inhalational agents are halothane, enflurane, isoflurane, and nitrous oxide. Older agents, such as ether and cyclopropane, are now used infrequently. The mechanism of action of all inhalational anesthetics is thought to involve uptake of the gas in the lipid bilayer of cell membranes and interaction with the membrane proteins, resulting in inhibition of synaptic transmission of nerve impulses. For surgical anesthesia, these agents are usually used with preanesthetic medication, which includes sedatives or opiates to relieve preoperative and postoperative pain and tranquilizers to reduce anxiety. Neuromuscular blocking agents are used as muscle relaxants during surgery. They include tubocurarine, metocurine, succinylcholine, pancuronium, atracurium, and vecuronium.

Intravenous anesthetics are sedative hypnotic drugs that produce anesthesia in large doses. The most common of these are the phenol derivative propofol and ultra–short acting barbiturates such as thiopental and methohexital; these can be used alone for brief surgical procedures or for rapid induction of anesthesia maintained by inhalational anesthetics.

Other intravenous methods of anesthesia are neuroleptanalgesia, which uses a combination of the butyrophenone tranquilizer droperidol and the opioid fentanyl; neuroleptanesthesia, which uses neuroleptanalgesia plus nitrous oxide; and dissociative anesthesia, which uses ketamine, a drug related to the hallucinogens that produces profound analgesia.

Local anesthetics are drugs that block nerve conduction in the region where they are applied. They act by altering permeability of nerve cells to sodium ions and thus blocking conduction of nerve impulses. They may be applied topically or injected into the tissues. The first local anesthetic was cocaine. Synthetic local anesthetics are all given names ending in -caine; examples are procaine and lidocaine.

an·es·thet·ic

(an'es-thet'ik),
1. A compound that reversibly depresses neuronal function, which produces loss of ability to perceive pain and/or other sensations.
2. Collective designation for anesthetizing agents administered to a person at a particular time.
3. Characterized by loss of sensation or capable of producing loss of sensation.
4. Associated with or owing to the state of anesthesia.

anesthetic

/an·es·thet·ic/ (an″es-thet´ik)
1. characterized by anesthesia; numb.
2. pertaining to or producing anesthesia.
3. an agent that produces anesthesia.

local anesthetic  an agent, e.g., lidocaine, procaine, or tetracaine, that produces anesthesia by paralyzing sensory nerve endings or nerve fibers at the site of application. The conduction of nerve impulses is blocked by stopping the entry of sodium into nerve cells.
topical anesthetic  a local anesthetic applied directly to the area to be anesthetized, usually the mucous membranes or the skin.

anesthetic

also

anaesthetic

(ăn′ĭs-thĕt′ĭk)
adj.
1. Relating to or resembling anesthesia.
2. Causing anesthesia.
3. Insensitive.
n.
1. An agent that causes loss of sensation with or without the loss of consciousness.
2. Something likened to this in effect: For some people watching television is an anesthetic for the mind.

an′es·thet′i·cal·ly adv.

anesthetic

a drug or agent used to abolish the sensation of pain, to achieve adequate muscle relaxation during surgery, to calm fear and allay anxiety, and to produce amnesia for the event.

anesthetic

adjective
1. Producing, referring or pertaining to, or characterized by anesthesia.
2. Characterized by a loss of sensation or awareness; numbness noun An agent or drug that abolishes the sensation of pain or awareness of surroundings. See General anesthetic, Inhalation anesthetic, Local anesthetic, Opioid anesthetic.

an·es·thet·ic

(an'es-thet'ik)
1. A compound that depresses neuronal function, producing loss of ability to perceive pain and/or other sensations.
2. Collective designation for anesthetizing agents administered to a person at a particular time.
3. Characterized by loss of sensation or capable of producing loss of sensation.
4. Associated with or due to the state of anesthesia.
Synonym(s): anaesthetic.

Anesthetic

Medicine that causes a loss of feeling, especially of pain. Some anesthetics also cause a loss of consciousness.

an·es·thet·ic

(an'es-thet'ik)
1. Agent or compound that reversibly depresses neuronal function, which produces loss of ability to perceive pain and/or other sensations.
2. Characterized by loss of sensation or capable of producing loss of sensation.
Synonym(s): anaesthetic.

anesthetic (an´esthet´ik),

n a drug that produces loss of feeling or sensation generally or locally.
anesthetic, aerosol spray topical,
n application of an aerosol spray directly on the surface of a mucous membrane, resulting in loss of nerve conduction.
anesthetic agent,
anesthetic, allergy to,
n hypersensitivity to a local agent, which is fairly common with esters but rarely occurs with amides. Allergy to bisulfites in vasoconstrictors also needs to be considered, as well as agents containing sulfites.
n a local anesthetic agent made from a specific class of chemical compounds that are broken down by the liver and are generally considered more effective and longer-lasting than esters. This type of anesthetic rarely causes allergic reactions.
anesthetic, antioxidants in,
n a preservative substance added by the manufacturer to a local anesthetic cartridge containing a vasoconstrictor. Metabisulfite and sodium bisulfite are the most commonly used antioxidants.
anesthetic, cartridge,
n a capsulelike vessel containing the local anesthetic solution that is inserted into the syringe in preparation for an injection. Older term is carpule.
anesthetic, ester,
n a short-acting local anesthetic agent made from a specific class of chemical compounds that are broken down by blood enzymes. They are less effective than amide anesthetics and more likely to cause allergic reactions. No longer used as an injection in the United States but still used as a topical agent. See also benzocaine.
anesthetic, hydrophilic group
n a portion of a local anesthetic agent's chemical structure, with strong water-attracting properties that enable the diffusion of the agent through the water portions of the tissues to the final destination in the nerves. Typically described in opposition to the lipophilic portion of a local anesthetic agent.
anesthetic, intermediate chain linkage,
n the connecting linkage between the lipophilic and hydrophilic portions of a local anesthetic agent's chemical structure. Local anesthetic agent's classification is performed on the basis of whether the intermediate chain is made up of an ester or an amide. See also ester and amide.
anesthetic, lipophilic group
n a portion of a local anesthetic agent's chemical structure, with its fat-attracting properties that enable the agent to pass through the lipid-membrane of the tissues in order to reach the nerve destination. Typically described in opposition to the hydrophilic portion of the local anesthetic agent.
anesthetic, local,
n a drug that, when injected into the tissues and absorbed into a nerve, will temporarily interrupt its property of conduction. See also anesthetic, ester and anesthetics, amide.
anesthetic, topical,
n a drug applied to the surface of the skin or mucosal tissues that produces local insensibility to pain. See also benzocaine.

anesthetic

1. pertaining to, characterized by, or producing anesthesia.
2. a drug or agent used to abolish the sensation of pain, to achieve adequate muscle relaxation during surgery, to calm fear and allay anxiety. See also anesthesia.

dissociative anesthetic
an anesthetic causing interruption of cerebral association pathways between the limbic system and cortical system. It produces a catalepsy-like state, in which the patient feels dissociated from its environment, and marked analgesia. Ketamine, phencyclidine and tiletamine hydrochloride are examples.
gaseous anesthetic
inhalation anesthesia. Halothane and isoflurane are commonly used agents.
general anesthetic
see general anesthesia.
anesthetic-induced rhabdomyolysis
see porcine stress syndrome.
inhalation anesthetic
gas or volatile liquid that produces general anesthesia when inhaled. The older agents, ether and cyclopropane, have been replaced by halothane, enflurane and isoflurane.
injectable anesthetic
sedative-hypnotic drugs produce anesthesia when administered in large doses. It can be administered intraperitoneally, but intravenous injection is much the most common route. Short-acting drugs, such as thiopentone, are used alone for very rapid procedures or for instrument examinations, or as induction for a longer term inhalation anesthetic. See also barbiturate. One anesthetic agent that is administered intramuscularly is ketamine.
irreversible anesthetic
the injection of a substance that destroys the peripheral nerve, e.g. ethyl or propyl alcohol.
local anesthetic
a drug that blocks nerve transmission in the nerves affected by the local presence of the drug. It may be applied topically, e.g. into the conjunctival sac, or by injection into tissues near the target nerve. Most local anesthetics are in the -caine series.
anesthetic machine
apparatus or equipment used to administer gaseous anesthetic agents; functions of the apparatus should include,
1. delivery of oxygen,
2. removal of carbon dioxide,
3. quantifiable delivery of anesthetic vapor or gas, and
4. capability of providing artificial respiration to the patient.
anesthetic scavenging
the use of any device to reduce the pollution of the air in surgeries caused by exhaled anesthetic gases. May be canisters of filtering material attached to the machine or suction lines at stragetic positions in the theater.
volatile anesthetic
see inhalation anesthetic (above).