Chp 11 Gen & Local anesthetics Flashcards
Anesthesics
drugs that reduce or eliminate pain by depressing nerve function in the central nervous system (CNS) and peripheral nervous system (PNS).
Anesthesia
the loss of the ability to feel pain resulting from the administration of an anesthetic drug.
Balanced anesthesia
the practice of using combinations of different drug classes rather than a single drug to produce anesthesia.
What are the two types of anesthesia?
- General - the CNS nerve impulses are altered to reduce pain and other sensations throughout the entire body. It involves the complete loss of consciousness and depression of respiratory drive.
- Local - peripheral or spinal nerve impulses are altered to reduce or eliminate pain and other sensations in tissues innervated by these nerves.
What happens in varying degrees under general anesthetics?
- pain relief
- depression of consciousness
- skeletal muscle relaxation
- reflex reduction
Inhalational anesthetics
Types of general anesthesia that are volatile liquids or gases that are vaporized or mixed with oxygen or medical air to induce anesthesia.
Examples of inhalational anesthetics:
Gas: nitrous oxide (laughing gas)
Volatile liquids: enflurane (Ethrane), halothane (Fluothane), methosyflurane (Penthrane), desflurane (Suprane), isoflurane (Forane), sevoflurane (Ultane)
Parenteral anesthetics
Types of general anesthesia that are given intravenously and are used for induction and/or maintenance of general anesthesia, induction of amnesia, and as adjuncts to inhalation-type anesthetics.
Examples of parenteral anesthetics:
etomidate (Amidate) propofol (Diprivan) ketamine (Ketalar) methohexital (Brevital) thiopental (Pentothal)
What are adjunct drugs used for in regards to anesthetics?
as “helper drugs” for anesthesia initiation (induction), sedation, reduction of anxiety, and amnesia.
What are some examples of sedative-hypnotic adjunct drugs?
- Barbituates (pentobarbital, secobarbital)
- Benzodiazepines (diazepam, midazolam)
- hydroxyzine
- promethazine
What are some examples of opioid analgesics adjunct drugs?
fentanyl, sufentanil, meperidine, morphine
What does NMBDs stand for?
neuromuscular blocking drugs
What are some examples of NMBDs?
- depolarizing drugs (succinylcholine, d-tubocurarine)
- nondepolarizing drugs (pancuronium, vecuronium)
What are anticholinergics?
drugs that block the action of acetylcholine.
What are some examples of anticholinergics?
atropine, glycopyrrolate, scopolamine
Overton-Meyer theory
a theory that describes the relationship between the lipid solubility of anesthetic drugs and their potency.
(proposes that, for all anesthetics, potency varies directly with lipid solubility)
According to the Overton-Meyer theory, are fat-soluble or water-soluble anesthetics stronger?
fat-soluble because nerve cell membranes have a high lipid content, as does the brain, the spinal cord, and the blood-brain barrier. Lipid-soluble anesthetic drugs can therefore easily cross the blood-brain barrier to concentrate in nerve cell membranes.
What is the overall effect of general anesthetics?
Orderly and systematic reduction of sensory and motor CNS functions
Progressive depression of cerebral and spinal cord fucntions
(The degree and speed of this process vary with the anesthetics and adjuncts used along with their dosages and routes of administration.)
Nystagmus
a condition of involuntary (or voluntary, in rare cases) eye movement
General anesthetics are used during surgical procedures to produce what results?
- unconsciousness
- skeletal muscular relaxation
- visceral smooth muscle relaxation
What additional treatments are general anesthetics used for?
electroconvulsive therapy for depression
What are the sites primarily effected by adverse effects of general anesthetics?
heart, peripheral circulation, liver, kidneys, respiratory tract
What adverse effect is commonly seen with general anesthesia?
myocardial depression
malignant hyperthermia
an uncommon, but potentially fatal, genetically linked adverse metabolic reaction to general anesthesia more classically associated with the use of volatile inhalational anesthetics as well as the depolarizing neuromuscular blocker, NMBD succinylcholine.