Anesthetics Flashcards
(32 cards)
Anesthesia
Abolition of sensation
Analgesia
Abolition of pain
Triad of general anestesia
need for unconsciousness, need for analgesia, need for muscle relaxation
Inhaled anesthetic agents
MAC: minimum alveolar anesthetic concentration. median concentration concentration that results in immobility in 50% of pts
Nitrous oxide, halothane, isoflurane, sevoflurane/desflurane,
Nitrous oxide
Simple, linear compound. Not metabolized. Only anesthetic agent that is INORGANIC
LOW POTENCY–MAC 105% (lower the MAC, more potent the drug)
Weak anesthetic, powerful analgesic; needs other agents for surgerical anesthesia
Low blood solubility (quick recovery)
NO systemic effects
minimal effects on heart rate and BP, respiration; safe.
May cause myocardial depression in sick pts
SEs: manufacturing impurities toxic, hypoxic mixtures can be used. large volumes of gases can be used. inhibits methionine synthetase (precurser to DNA synthesis), vit B-12 metab.
Dentists, OR personnel, abusers at risk
Halothane
Volatile liquid, easily vaporized, stable and nonflammable Most potent inhalational anesthetic MAC: 0.75% efficacious in depressing consciousness Very soluble in blood and adipose Prolonged emergence
Halothane s/es
HALOTHANE HEPATITIS--1/10,000: fever, jaundice, hepatic necrosis, death. Malignant hyperthermia (more common w/ succinylcholine): Classic--rapid rise in body temp, muscle rigidity (masseter), tachycardia, rhabdo, acidosis, hyperkalemia, DIC (coagulation). Autosomal dominant. Dx: sx, increase CO2, rise in CPK levels, myoglobinuria, muscle bx. physiology: hypermetabolic state by inhibition of calcium reuptake in sarcoplasmic reticulum. tx: early detection! d/c agents, hyperventilate, give bicarb, IV dantrolene, cool pt, lasix/mannitol/fluids, ICU. prophylaxis: preop IV dantrolene
Isoflurane
Not carcinogenic
Nonflammable, pungent
Less soluble than halothane
MAC: 1.3%
Isoflurane systemic effects
Depresses respiratory drive and ventilatory responses
Myocardial depressant
Inhibits sympathetic baroreflex response
sensitizes myocardium to catecholamines (less than halothane)
PRODUCES MOST SIGNIFICANT REDUCTION IN SYSTEMIC VASCULAR RESISTANCE–coronary steal syndrome, increased ICP
Excellent muscle relaxant–potentiates effects of neuromuscular blockers
Isoflurane side effects
Little metabolism (0.2%)–low potential of organotoxic metabolites
No EEG activity
Bronchoirritating, laryngospasm
Sevoflurane and Desflurane
Low solubility in blood–produces most rapid induction and emergence
minimal systemic effects–mild resp and cardiac suppresion
few side effects
expensive
IN Anesthetic agents
Many options: muscle relaxants, opoids, nonopoids.
appealing, pleasant experience
Agents: etomidate, ketamine, propofol/fospropofol, benzadiazepines
(diazepam, lorazepam, midazolam), opiods (narcotic agonists), muscle relaxants
Etomidate
Structure similar to ketoconazole
Direct CNS depressant (thiopental) and GABA agonist
Systemic effects: little change in cardiac function, mild resp depression. decreased cerebral metabolism
ADRs: injection site, myoclonic activity, N/V (50%), cortisol suppresion
Ketamine
Structurally similar to PCP
interrupt cerebral association pathways–“dissociative anesthesia”
stimulates central sympathetic pathways
systemic effects: characteristic of sympathetic nervous system stimulation–increase HR, BP, CO. maintains laryngeal reflexes and skeletal muscle tone
ADRs: emergence can produce hallucinations and unpleasant dreams
Propofol/fospropofol
Rapid onset and short DOA. pt remembers NOTHING
Myocardia depression and peripheral vasodilation may occur–basoreflex NOT suppresed.
Propofol not water soluble, painful. Fospropofol soluble in water.
Benzodiazepines
Produce sedation and amnesia
Potentiate GABA receptors–allosteric binding, bind to different site at same receptor
Slower onset and emergence
Agents: Diazepam, Lorazepam, Midazolam
Diazepam
Valium
Often used as premedication or seizure activity, rarely for induction
Minimal systemic effects–resp decreased with narcotic usage
Not water soluble–venous irritation
Metabolized by liver–not redistributed
Lorazepam
Ativan
Slower onset of action (10-20min). not used for induction
used as adjunct for anxiolytic and sedative properties
not water soluble–venous irritation
Midazolam
Verset.
quickest onset and emergence only if used for a short period of time.
More potent than diazepam or lorazepam
Induction slow, recovery prolonged
May depress resp when used with narcotics
minimal cardiac effects
water soluble
Benzo toxicity
Excessive sedation, resp depression, coma
Flumanzenil is anidote–may need repeated dosing. 0.2mg over 30 sec, wait 30 sec, then 0.3mg over 30 sec, then 0.5mg every 60 sec up to max 3mg
Narcotic agonists
Opoids
Analgesia, depression of sensorium and respiration
MOA: Receptor mediated
Minimal cardiac effects–no myocardial depression. Bradycardia in large doses
Some peripheral vasodilation and histamine release–hypotension
SEs: N, chest wall rigidity, seizures, constipation, urinary retention
Agents: alfentanil, fentanyl, sufentanil, remifentanil
Naloxone is pure antagonist that reverses analgesia and resp depression w/in 30 min
Muscle relaxants
MOA: occurs at the neuromuscular junction inhibition. blocks the effects of ACH at NMJ.
Nondepolarizing muscle relaxants
Competitively inhibit end plate nicotinc cholinergic receptor
Short acting: rocuronium
Intermediate (15-60m): cisatracurium, vecuronium, mivacurium
long acting: pancuronium, tubocurarine.
difference–renal function
Reversal by anticholinesterase–inhibit acetylcholinesterase: neostigmine, pyridostigmine, edrophonium
