Term
| What was the first general anesthetic? |
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Definition
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Term
Function
general anesthesia |
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Definition
reversible depression of the CNS =>
1) unconsciousness
2) analgesia (pain killer)
3) amnesia
4) immobility |
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Term
| What are the 2 classes of general anesthesia? |
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Definition
1) inhalation
2) intravenous |
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Term
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Definition
| combination of inhaled & intravenous anesthesia to take advantage of the favorable properties of each agent while minimizing their adverse reactions |
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Term
| What are the 2 theories of anesthesia? |
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Definition
1) Lipid theory (lipid soluble = potency)
2) protein theory |
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Term
def
MAC (minimum alveolar concentration) |
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Definition
| measure of inhaled anesthetic potency - the alveolar concentration required to immobilize 50% of patients when exposed to a surgical incision |
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Term
| What happens to MAC values when several anesthetics are used simultaneously? |
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Definition
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Term
| What factors can make MAC vary among patients? |
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Definition
1) Age
2) EtOH
3) underlying disease
4) DDIs
(NOT affected by height, weight, sex) |
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Term
def
oil:gas partition coefficient |
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Definition
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Term
Equation
Potency on anesthetic |
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Definition
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Term
| What is the Unitary Theory of Anesthesia (lipid theory)? |
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Definition
Anesthetics work by changing membrane dimension &/or membrane state.
dimension: change volume of membrane
physical state: increase fluidity |
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Term
| What is the protein theory of anesthesia? |
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Definition
| anesthetic interacts directly with hydrophobic domain of any membrane protein |
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Term
| What are the primary targets of general anesthestics (GAs)? |
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Definition
ligand-gated ion channels:
-GABA
-nAchR
-Glu
-5-HT3
-NMDA |
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Term
What are the 2 inhibitory receptors that GAs work on?
3 excitatory? |
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Definition
I: Glu & GABA
E: 5-HT3, NMDA, nAchR |
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Term
MOA
GA on inhibitory receptors (GABA & Glu) |
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Definition
| potentiate the action of endogenous agonists (stabilizes open state) => decreased AP at post-synaptic neuron => more potent agonists (i.e. need less concentration of agonists to achieve maximum response - decrease EC50) |
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Term
MOA
GAs on excitatory receptors (5-HT3, NMDA, nAchR) |
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Definition
| inhibits the action of endogenous agonists => no depolarization of post synaptic membrane => no AP (like adding a non-competitive antagonist, EC50 stays the same, but efficacy decreases) |
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Term
def
dual process model of anesthesia |
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Definition
1) inhibits excitatory receptors
2) ehances inhibitory receptors |
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Term
| Why are GAs the most dangerous drugs in clinical use? |
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Definition
| low safety margin & no antagonist |
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Term
| What are the 2 types of inhaled GAs? |
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Definition
1) non-halogenated
2) halogenated |
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Term
| What is the inhalation non-halogenated GA? |
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Definition
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Term
| What are the 4 halogenated inhalation GAs? |
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Definition
(volatile liquid):
sevoflurane, isoflurane, halothane, desflurane |
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Term
| What inhaled anesthetic has the highest MAC? |
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Definition
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Term
SOA
NO inhalation anesthetic |
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Definition
| analgesic (only used alone in dental procedures) |
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Term
SOA
halothane inhalation anesthetic |
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Definition
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Term
SOA
isoflurane inhalation anesthetic |
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Definition
most widely used
induction/maintenance |
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Term
SOA
desflurane inhalation anesthetic |
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Definition
| most widely used for outpatient surgery |
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Term
SOA
sevoflurane inhalation anesthetic |
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Definition
induction in children
outpatient surgery |
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Term
SE
inhaled anesthetic on cardiovascular system |
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Definition
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Term
SE
inhaled anesthetic on resp. system |
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Definition
| reduce or eliminate ventilatory drive & reflexes maintaining aairway patency (all except NO) |
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Term
SE
inhaled anesthetic on brain |
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Definition
| increase cerebral blood flow => increased cerebral blood volume => increased ICP |
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Term
SE
inhaled anesthetic on kidney |
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Definition
| decrease glomerular filtration rate & renal blood flow => increased filtration fraction |
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Term
SE
inhaled anesthetic on liver |
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Definition
| concentration-dependent decrease in hepatic blood flow (15-45% reduction) |
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Term
def
malignant hyperthermia |
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Definition
| autosomal dominant genetic disorder of skeletal muscle that occurs in susceptible individuals undergoing GA with volatile agents & muscle relaxants. An increase in free [Ca2+] in skeletal muscle => increase in anesthetic morbidity & mortality. |
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Term
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Definition
rapid onset tachycardia & HTN
severe muscle rigidity
hyperthermia
hyperkalemia
acidosis |
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Term
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Definition
| dantrolene to prevent Ca2+ release from SR |
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Term
| What factor determines rate of uptake of an anesthetic & its distribution throughout the body? |
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Definition
| solubility in blood & body tissue |
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Term
| How is solubility of inhalation anesthetics most commonly measured & expressed? |
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Definition
| Blood:Gas partition coefficient |
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Term
def
blood:gas partition coefficient |
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Definition
| main factor that determines the rate of induction & recovery from anesthesia (relative affinity for the blood compared to air) |
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Term
| When will there be faster induction & recovery from a GA? |
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Definition
| lower the blood:gas partition coefficient |
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Term
| Why does a low blood:gas partition mean faster induction & recovery? |
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Definition
| equilibriate faster since less has to be transferred via the lungs to the blood in order to achieve a given partial pressure |
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Term
| What 2 inhaled anesthetics have a higher blood:gas partition coefficient? |
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Definition
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Term
| How does blood flow affect GA? |
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Definition
| the greater the blood flow (perfusion), the faster the uptake of the anesthetic |
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Term
def
tissue capacity for a GA |
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Definition
| volume of compartment & solubility of anesthetic in tissue |
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Term
| What are the 3 groups of tissue based on their perfusion & capacity to take up anesthesia? |
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Definition
1) high flow, low capacity (brain, lung, heart, kidney)
2) medium flow, high capacity (skeletal muscles)
3) low flow, very high capacity (adipose tissue) |
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Term
Which tissue group has the fastest rise in partial pressure of the anesthetic?
slowest? |
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Definition
fast: high flow, low capacity
slow: slow flow, very high capacity |
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Term
| How does % body fat affect uptake & distribution of a GA? |
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Definition
| highlt lipid soluble dug + high body fat = slow recovery & patient remains drowsy |
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Term
| What does the rate of the rise of anesthetic gas tension in arterial blood depend on? |
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Definition
rate & depth of ventilation
magnitude varies dependent on the blood:gas partition coefficient |
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Term
| How do you increase the rate of onset of an inhaled anesthesia? |
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Definition
| increase the ventilation rate (hyperventilation) due to increased concentrations of the agent |
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Term
| What happens to the rate of induction of an inhaled anesthetic when pulmonary blood flow increases (i.e. increase in cardiac output)? |
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Definition
| slows (effect is larger for more blood soluble gases) |
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Term
| Why does increased pulmonary blood flow decrease the rate of induction of an inhaled anesthetic? |
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Definition
| increased blood flow = larger volume of blood exposed to anesthetic => takes longer for anesthetic & blood to equilibrate |
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Term
| How are inhaled anesthetics cleared from the body? |
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Definition
Major route: lungs
Minor route: some metabolism in liver |
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Term
| How are inhaled anesthetics terminated? |
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Definition
| redistribution from brain to the blood, down partial pressure gradient |
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Term
| Is rate of recovery from inhaled anesthetics faster with a high or low blood:gas partition coefficient? |
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Definition
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Term
| What is rate of recovery from an inahled anesthetic proportional to? |
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Definition
| duration under anesthesia. (the longer it's applied, the more anesthsia distributes to muscle groups & fat) |
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Term
| Does hyper- or hypo- ventilation increase rate of recovery from an inhaled anesthetic? |
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Definition
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Term
| Which inhaled anesthetic is the only one with a significant portion of it (~40%) metabolized? |
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Definition
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Term
DO IV anesthetics have a more or less rapid rate of induction than inhaled anesthetics?
Why? |
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Definition
| More rapid b/c they're more lipid soluble & easily cross the BBB |
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Term
| Why are IV anesthetics often used for outpatient procedures? |
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Definition
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Term
| In balanced athesthesia, are IV anesthetics administered pre or post inhaled anesthetics? |
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Definition
| pre, due to rapid onset & short duration of action |
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Term
| Where is IV anesthetics trasported first via the vascular system? |
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Definition
| heart => brain & highly vascularized tissues (peak within 1 min) |
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Term
| Why is drug redistribution to adipose much later in IV anesthetics? |
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Definition
| low blood flow to body fat |
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Term
| How are IV anesthetics eliminated? |
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Definition
| liver/plasma metabolism (NOT ventilation) |
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Term
| What are the 4 IV anesthetics used? |
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Definition
1) Barbituates
2) Propofol
3) Etomidate
4) Ketamine |
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Term
| What 3 barbituates are used as IV anesthestia? |
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Definition
1) Sodium Thiopental
2) Thiamylal
3) Methohexital |
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Term
Onset/Duration
barbituates |
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Definition
| rapid onset(seconds)/ultra-short |
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Term
| What is the most populat IV anesthetic? |
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Definition
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Term
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Definition
| rapid (half time to blood-brain equilibriation is 1-3min) |
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Term
| Why is propofol a good choice anesthetic for outpatient procedures? |
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Definition
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Term
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Definition
outpatient procedures
critical care prolonged sedation |
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Term
| Where is porpofol rapidly metabolized? |
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Definition
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Term
| What IV anesthetic is the analog to PCP & produces dissociative anesthesia? |
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Definition
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Term
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Definition
hallucinations
irrational behavior
dose-related cardiovascular stimulation (only IV anesthesia to do so) |
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Term
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Definition
| induction & maintenance (usually in comination with a sedative) |
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Term
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Definition
| noncompetitive antagonist of NMDA |
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Term
def
dissociative anesthesia |
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Definition
catatonia
amnesia
analgesia
w/o loss of consciousness |
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Term
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Definition
| rapid-acting w/ profound analgesia |
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Term
| Where is katamine metabolized? |
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Definition
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Term
For which patients is etomidate primarily used?
Why? |
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Definition
| those @ risk for hypotenstion b/c does not cause significant cardiovascular or resp. depression |
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Term
What is usually co-administered with etomidate?
Why? |
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Definition
| Lidocaine b/c high incidence of pain on injection |
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Term
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Definition
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Term
| Where is etomidate metabolized |
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Definition
| extensively in plasma & liver to inactive metabolites |
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Term
| What 2 drug types are used as adjuvants, but also have some anesthetic quality when administered IV? |
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Definition
1) benzodiazepines
2) opioids |
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Term
| What are the 3 benzodiazepines used as an adjuvant to GA? |
|
Definition
1) Diazepam
2) Lorazepam
3) Midazolam |
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Term
| Why are benzos given as an adjuvant to GA? |
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Definition
| anxiolytic & anterograde amnestic propeties |
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Term
SOA
benzos as an IV anesthetic |
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Definition
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Term
| What are the 2 opioids used as an adjuvant to GA? |
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Definition
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Term
| Why are opioids used an adjuvant to GA? |
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Definition
| analgesia (poor amnestics) |
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Term
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Definition
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