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68 Cards in this Set
- Front
- Back
- 3rd side (hint)
Review the differences between "induction" "maintenance" and "emergence"
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page 209
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Since inhalational anesthetics are gases, how is the partial pressure of these gases useful as a measurement?
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partial pressure is proportional to concentration
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How are inhalant general anesthetics transferred from one compartment to another?
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passive diffusion down their partial pressure gradients
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Name the compartment inhalant general anesthetics pass through on their way to the CNS.
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inspired gas --> alveoli --> blood --> target CNS and other tissues
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What is the inhalent general anesthetic concentration in the CNS dependent upon?
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the final alveolar tension
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what 3 things govern the rate of induction of a general anesthetic?
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1. Rate of equilibration (which is dependent on the tension of the anesthetic of the inspired gas + pulmonary ventilation rate)… 2. Rate of blood equilibration (which is dependent on the blood solubility of the drug, where the lower the blood solubility coefficient = faster rate, because the more blood soluble the slower the induction and the slower the equilibration)... 3. Rate of Tissue Equilibration (which is dependent on tissue blood flow rates... brain>heart>lung... etc.)
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Which of the 3 things that govern induction rates of general anesthetic is most critical?
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blood solubility
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If general anesthetics are generally fat soluble, why do drugs take so long to equilibate in fatty tissue?
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poor blood flow to fatty tissues
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What governs rate of emergence?
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the same factors that govern induction
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T/F metabolism and renal clearance play a significant role in the elimination of inhalational anesthetics.
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FALSE… they play a minimal role
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What determines the potency of a inhalation anesthetic?
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it's lipid solubility
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T/F the more lipid soluble an inhalation anesthetic the less tension it require to produce anesthesia.
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TRUE
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Do lipid soluble inhalation anesthetics tend to have low or high blood solubility?
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they have high blood solubility, while they are more potent they tend to be slow inducers
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What does MAC stand for? (2 things)
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1. MAC = minimum alveolar concentration anesthetic needed to produce immobility in 50% of patients… 2. it's an index of potency…
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What is a good measure of brain tension for inhalation anesthetics?
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alveolar tension = brain tension
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T/F MAC can only be applied to inhalation anesthetics if they were nor a solid or liquid first.
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false all inhalation anesthetic are ranked by MAC
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T/F MAC is stable across a variety of conditions, e.g., gender, height, acid-base status.
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TRUE
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T/F MAC is additive for different inhalant anesthetics.
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TRUE
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Which is the most potent inhalational anesthetic? Which is the intermediate MAC? Which ihalent has the least potent?
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most potent = Halothane…Intermediate = Isoflurane... least potent = NO
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None
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What is considered a potent MAC a large value or small value?
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small
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Which inhalational anesthetic cause a decrease in intracranial pressure (while the other cause an increase.)?
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Decrease = Isoflurane… increase = NO and Halothane
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Which inhalational anesthetic would require pretreatment to avoid airway irritation?
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Isoflurane, which is the the only inhalational anesthetic that causes airway irrititation
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None
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Which inhalational anesthetic would you avoid if the patient has issues of low blood pressure?
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isoflurane and halothane, which both cause significant hypotension… use NO instead
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Between NO, halothane and isoflurane, which has the lowest blood solubilitiy? What is the consequence of this?
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NO… which makes it a rapid inducer… the other have a medium rate of induction
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T/F NO, halothane and isoflurane all have analgesic effects.
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TRUE
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which inhalation anesthtic will cause hypoxia at partial pressures of 70-80%?
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NO (diffusion hypoxia)
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None
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In NO use, what happens during rapid emergence that causes a large drop in PaO2? And what is this effect called?
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NO saturates the alveoli… this is called the diffusion hypoxia effect
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Why is NO used as an adjuct with other inhalation anesthetics?
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becaues of its low potency and risk for hypoxia
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Rank the inhalational anesthetics in order of greater to least muscle relaxation effects.
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Isoflurane > halothane> NO (yes>minimal>none)
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Rank the inhalational anesthetics in order of greater to least respiratory system effects.
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Isoflurane (potent respiratory depressant) > Halothane (causes moderate reduction in rate) > NO (minimal effect)
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Which is the only inhalational anesthetic that comes in a gas form?
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NO.. The others are in volitile liquid form
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why is isoflurane a good choice for neurosurgery?
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isoflurane decreases cerebral blood flow and lowers intercranial pressure
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Which is the most potent inhalation anesthetic?
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isoflurane
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which inhalation anesthtic will cause liver nicrosis in adults, but is still used in pediatrics?
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halothane
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which inhalation anesthtic will cause coughing and layrngospams and requires premedication or use of thiopental as an induction agent?
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Isoflurane
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What is the advantage of IV general anesthetics?
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fast onset and ultra short acting… but moreover they are highly POTENT!!!!
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Why is the combination of IV general anesthetics and inhalation anesthetics useful?
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IV general anesthetics lowers the doses of inhalational anesthetics
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What properties do all IV general anesthetics share?
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all are IV injected and all are lipophilic (which makes sense in terms of potency)
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Why is the CNS preferentially targeted by IV general anesthetics?
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the CNS is highly perfused and lipophilic friendly
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What two things is the rate of induction for IV general anesthetics dependent upon?
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1. Lipid solubility of the IV general anesthetics… 2. The administered dose (i.e., one large bolus)
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where do IV general anesthetics redistribute after first going to the CNS?
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1. First, the less well perfused muscle and viscer… 2. Then the hydrophobic, but poorly perfused adipose tissues
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After redistribution, how are IV general anesthetics cleared from the body?
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liver metabolism and renal excretion
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Which is more responsible for emergence for IV general anesthetics, liver metabolism, renal excretion, or redistribution? (not continuous or intermittent use!!!)
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redistribution
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1. If the IV general anesthetics is used continuously or intermittently for a prolonged period, Which is more responsible for emergence for IV general anesthetics, liver metabolism, renal excretion, or redistribution?… 2. What then determines IV general anesthetics elimination half-life?
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1. Since the drug has equilibrated in all tissues, termination of drug action is now dependent on elimination from the body… 2. Infusion DURATION.
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What is the best example emergence being dependent upon infusion duration?
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a single bolus dose of thiopental has rapid emergence, while prolonged infusion takes a day to emerge
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How are IV general anesthetics measured?
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potency (lipophilicity) and dose
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Which IV general anesthetics is a barbiturate?
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Thiopental
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which IV general anesthetics is a phenol?
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Propofol
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Which IV general anesthetics is susceptible to bacterial contamination?
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propofol
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Which IV general anesthetics dissociates the thalamus from the limbic cortex?
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Ketamine
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Which IV general anesthetics have lipid solubility and high potency?
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all of them
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Which IV general anesthetics is a synthesized as a Na-salt from propylene glycol, alcohol and water?
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thiopental
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which IV general anesthetics is similar to PCP?
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ketamine
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Which IV general anesthetics increases CO, HR, and BP?
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ketamine
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which IV general anesthetics can increase the risk of seizure in epileptic patients?
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propofol
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which IV general anesthetics decreases intracranial pressure?
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thiopental
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Which of the IV general anesthetics offers analgesic properties?
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ketamine
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Which IV general anesthetics produce early airway irritation?
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thiopental
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which IV general anesthetics can allergic rxns in patients with a phenol allergy and has a high incidence of injection pain?
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propofol
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which IV general anesthetics can cause hypotention?
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thiopental can cause hyptension in hypovolemic patients… propofol can cause moderate hypotension
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Which IV general anesthetics can cause dose dependent respiratory depression?
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both propofol and thiopental
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which IV general anesthetics does not shows prolonged emergence due to prolonged infusion? What does this mean for its use as a maintenance anesthetic?
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propofol… quick emergence --> it's a good maintenance IV general anesthetics
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Which IV general anesthetics has a slow-long emergence?
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thiopental
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which IV general anesthetics can be titrated to achieve various levels of consciousness?
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propofol
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Which IV general anesthetics can produce severe pain and necrosis if accidental extravascular injection occurs?
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thiopental
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Which drug is has an active metabolite, is an analog of PCP, can develop tolerance, and is a potent broncho dilator?
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ketamine
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How do general anesthetics work?
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change activity of voltage gated and ligand gated channels (Ca), also GABA receptor have increased sensitivity… except NO is thought to depress the nervous system by inhibiting NMDA receptors
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which inhalent is sweet smelling?
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Halothane... used for kids
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