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IV anesthetics
Pharm (Test 3)
| Question | Answer |
|---|---|
| Which drug is the "gold standard" for IV anesthetics? | pentothal/thiopental |
| IV anesthetics are also known as... (3) | 1)IV induction agents, 2)sedatives, 3)hypnotics |
| Which IV anesthetic is referred to as a "dissociative drug"? | ketamine |
| True or False: IV anesthetics, typically, are drugs injected to induce unconsciousness at the beginning of general anesthesia, but allows rapid recovery after the end of its effect. | True |
| How do IV anesthetics alter a pt's level of consciousness? | by depressing the reticular activating system either by 1)enhancing the inhibition properties of GABA or 2)inhibiting the NMDA excitatory synapses |
| Which 2 IV anesthetics can be used for TIVA? | propofol or ketamine |
| How much CO does the vessel-rich group (brain, heart, liver, kidneys, endocrine) receive? | 75% |
| How much CO does the lean muscle group (muscle, skin) receive? | 19% |
| How much CO does the fat group receive? | 6% |
| How much CO does the vessel-poor group (bone, ligament, cartilage) receive? | 0% |
| What term describes the time in which the drug starts losing it's effect? | redistribution 1/2 time |
| What term describes the time when the drug actually exits the body? | elimination 1/2 time |
| What is the primary mechanism for terminating the central effect of IV induction agents? | their redistribution from the central, highly perfused compartment to the larger, less-well perfused "peripheral" compartments |
| What is the "alpha" phase of metabolism? | redistribution -- the plasma concentration of the drug has declined to the point that the drug moves out of the vessel-rich central group and is then taken into the peripheral group |
| What is the "beta" phase of metabolism? | elimination -- involves metabolism and excretion |
| Equilibrium with skeletal muscles is reached in about ______min after IV injection of thiopental. | 15min |
| True or False: Large or repeated doses of lipid-soluble barbiturates produce a cumulative effect because of storage capacity of fat. | True |
| What are the only IV anesthetics that enhances opioid analgesia? | ketamine, dexmetetomidine, and propofol |
| What class of drug is pentothal/thiopental? | barbiturate (sulfur) |
| What is the preparation of thiopental? | 2.5% sodium salt preparation |
| Thiopental is (lipid or water?) soluble in preparation. | water |
| What is the pH of prepared thiopental? | 10.5 (highly alkaline) |
| How does the alkalinity of thiopental act as an advantage? | bacteriostasis -- bacteria can't grow like in propofol |
| Thiopental is (stable or unstable?) once reconstituted? | unstable; lasts only 6days at room temp and 2 weeks in frig |
| Which drugs can precipitate when mixed with thiopental? | opioids, catecholamines, NMB (NMB will turn thiopental to concrete) |
| Does thiopental cause pain on injection? | minimal |
| True or False: Thiopental forms crystals when injected arterially. | True |
| What is the mechanism of action of pentothal? | 1) increases duration of GABA activating its receptor, causing Cl- channels to remain open, hyperpolarizing membrane, 2) mimics GABA at its own receptor, causing Cl- channels to open, 3)activates glutamate, adenoside, and nACh receptors |
| Which mechanism of action of pentothal causes the hemodynamic effects? | SNS ganglia depressed transmission |
| Thiopental (sensitizes or desensitizes?) nACh receptors to the depolarizing effects of ACh. | desensitizes |
| How dangerous are pentothal's CV effects compared to other drugs of this class? | minimal |
| What are thiopental's CV effects? | transient dec. in BP, accompanying inc. in HR, peripheral dilation (venous pooling, dec. venous return), less myocardial depressive effects than volatiles |
| How much does a 5mg/kg dose of pentothal affect BP and HR? | 10-20mmHg dec. in BP, 15-20 beat inc. in HR |
| Does pentothal cause histamine release? | possibly |
| True or False: Slowing the rate of administration of pentothal can dec. the CV changes. | False |
| What are thiopental's respiratory effects? | dec. sensitivity if medullary ventilator center to stimulation of CO2, apnea more likely when given w/ opioids/benzos, resp. returns as small TV and slow RR |
| How does thiopental affect airway reflexes? | reflexes remain intact, possibility of laryngospasm |
| Thiopental (increases or decreases?) ICP. | decreases (cerebral vasoconstriction which decreases cerebral blood flow) |
| Thiopental decreases CMRO2 by _____%. | 55% (the most of our drugs) |
| What types of cerebral ischemia can be protected by thiopental? | incomplete cerebral ischemia (coronary bypass, hypotension, circ. arrest) |
| What types of cerebral ischemia cannot be protected by thiopental? | global cerebral ischemia (cardiac arrest) |
| What dose of thiopental can cause isoelectric EEG? | 37.5mg/kg |
| Does thiopental cause liver or kidney damage? | no (slight dec. in flow d/t dec. BP/CO) |
| Can thiopental be given to pt's w/ porphyria? | no (stim. and inc. production of heme --> acute intermittent porphyria may be exacerbated) |
| Thiopental (does or doesn't?) cross placenta? | does |
| Can thiopental lead to tolerance and dependence? | yes |
| Can thiopental lead to anaphylaxis and anaphylactoid reactions? | yes |
| What is thiopental's distribution 1/2 time? | 2-4 min |
| What is thiopental's elimination 1/2 time? | 10-12 hrs |
| True or False: Thiopental is water-soluble in preparation and lipid-soluble at physiologic pH. | True |
| _____% of thiopental is protein bound. | 85% |
| What is the dose of thiopental? | 3-5mg/kg |
| What is pentothal's onset? | 30 sec |
| What is thiopental's duration? | 5-10 min |
| Does thiopental cause a "hangover"? | yes |
| What are some advantages to using thiopental? | minimal CV effects, minimal pain on injection, good cerebral protection (55%), possible isoelectric EEG |
| What are some disadvantages to using thiopental? | dec. resp response to CO2, airway reflexes remain intact, hangover, moderate emetic, precipitation, can't give to pts w/ porphyria, crosses placenta, tolerance/dependence, anaphylaxis, unstable reconstituted |
| What class of drug is brevital/methohexital? | barbiturate (oxybarbiturate) |
| How is methohexital prepared? | 1% solution |
| Brevital is (stable or unstable?) reconstituted? | stable (6wks in frig) |
| What is methohexital's MOA? | GABA (like thiopental) |
| How does methohexital's lipid-solubility compare to pentothal? | less lipid soluble |
| How does methohexital's metabolism compare to pentothal? | 3-4X faster (d/t dec. lipid solubility, smaller vol. of dist.) |
| How does methohexital's hangover compare to pentothal? | less hangover |
| How does methohexital's awakening time compare to pentothal? | faster |
| What is brevital's elimination 1/2 time? | 3.9 hrs (2-5 hrs) |
| What are the CV effects of methohexital? | similar to thiopental (maybe less hTN d/t inc. in HR better preserved) |
| Does methohexital cause histamine release? | no |
| Can methohexital cause exascerbation of acute intermittent porphyria? | yes |
| What are some advantages to brevital? | more rapid recovery than thiopental, good CV profile, cerebral protection (not as much as thiopental), less hangover than thiopental |
| What are some disadvantages to methohexital? | exascerbation of acute intermittent porphyria, more excitatory activity, myoclonus, hiccoughs, moderate emetic |
| How does methohexital's potency compare to thiopental? | 2.5X more potent (d/t less lipid solubility) |
| True or False: Methohexital's excitatory activities are dose-dependent. | True |
| How can you decrease incidence of brevital's excitatory activity, myoclonus, hiccoughs? | inclusion of opioids pre-op and dose of 1-1.5 mg/kg of brevital |
| What is an induction dose of methohexital? | 1-2mg/kg |
| What is a sedation dose of methohexital? | 0.2-0.4mg/kg |
| What is a rectal dose of methohexital? | 25mg/kg |
| What is the onset of brevital? | 30sec |
| What is the duration of methohexital? | 5-10 min |
| What is the distribution 1/2 time of methohexital? | 5.6 min |
| True or False: Etomidate is chemically unrelated to any other IV anesthetic. | True |
| True or False: Etomidate has a carboxylate imidazole-containing compound (water-soluble at acidic pH and lipid soluble at physiologic pH). | True |
| How is etomidate prepared? | 0.2% in propylene glycol |
| What is prepared etomidate's pH? | 6.9 |
| Does etomidate cause pain on injection? | yes (propylene glycol) |
| What is etomidate's MOA? | mimics inhibitory effects of GABA by increasing the receptors affinity to GABA, thus depresses the reticular activating system |
| What is the incidence of excitatory activity to cause myoclonus w/ etomidate? | 30-60% |
| What are etomidate's CV effects? | dec MAP (15%, minimal), minimal changes in HR, SV, CO, dec in SVR, depressed myocardium less than thiopental, no dec. in renal blood flow |
| Does etomidate cause histamine release? | no |
| How does etomidate's resp effects compare to barbiturates? | less resp effects |
| What are etomidate's resp effects? | dec. TV, but inc. RR, apnea doesn't always occur, apnea more likely w/ opioids/benzos/volatiles |
| Etomidate dec. CMRO2 by _______%. | 35-45% |
| True or False: Etomidate should be avoided in pts w/ seizure disorders. | True (d/t excitatory activity) |
| What are some advantages to etomidate? | best CV profile, less resp effects (not always apnea), cerebral protection (35-45% dec in CMRO2) |
| What are some disadvantages to etomidate? | excitatory activity (avoid in seizure pts), adrenocortical suppression (avoid in septic and bleeding pts), commonly emetic, pain on injection |
| How does etomidate cause adrenocortical suppression? | inhibition of the conversion of cholesterol to cortisol (inhibition of the enzyme which performs 11-beta-hydoxylation reaction) |
| How quickly does etomidate dec. cortisol and aldosterone levels? | 30min after single dose |
| How long does the adrenocortical suppression from etomidate last? | 4-8 hrs after dose (up to 48hrs) |
| True or False: Pretreating w/ a dose of steroid before dose of etomidate can prevent adrenocortical suppression. | False |
| Etomidate's action is limited by... | redistribution |
| Compare etomidate's metabolism to that of thiopental. | 5X faster |
| What is the dose of etomidate? | 0.3mg/kg |
| What is the onset of etomidate? | 14-45sec |
| What is the duration of etomidate? | 3-12min |
| What is the distribution 1/2 time of etomidate? | 2-4 min |
| What is the elimination 1/2 time of etomidate? | 2-5 hrs |
| What class of drug is dexmetetomidine/precedex? | alpha2 adrenergic agonist |
| What is precedex's MOA? | (in spinal cord and locus coeruleus) hyperpolarization with efflux of K+, reduced NE release d/t presynaptic receptors, dec. cAMP cntn by inhibiting adenylyl cyclase |
| True or False: Precedex is often used for induction? | False (prob. not ever) |
| What are dexmetetomidine's CV effects? | hypertension (r/t loading dose), dec. HR, BP (possible heart block) |
| What are some advantages to dexmetetomidine? | sedation/analgesia w/ little vent. depression, less delirium than benzos, sedation similar to sleep, wean vent w/o titration, easily arousable, dec. MAC by 90%, antisialogauge, some analgesic effect, reduces shivering |
| True or False: Dexmetetomidine is not approved for general anesthesia. | True |
| True or False: Precedex is a good alternative to ketamine for awake fiberoptic intubation. | True |
| What is the distribution 1/2 life of precedex? | 6-8 min |
| What is the context sensitive 1/2 time of dexmetetomidate? | after 1 hr=25-120min, after >6hrs=87-250 min |
| What is a loading dose of dexmetetomidine? | 0.5-1mcg/kg over 10 min |
| What is the infusion dose of dexmetetomidine? | 0.2-1.4mcg/kg/hr |
| Which IV anesthetic has the worst resp effects? | propofol |
| Which IV anesthetic supports spont resp? | ketamine |
| Which IV anesthetic is the least resp depressant? | etomidate |
| Which IV anesthetic has the worst hangover? | pentothal |
| Which IV anesthetic has the least hangover? | propofol |
| Which IV anesthetic can cause hallucinations? | ketamine |
| Which IV anesthetic is the only antiemetic? | propofol |
| Which IV anesthetic is the worst emetic? | etomidate |
| Which IV anesthetic affect adrenocortical function? | etomidate |
| Which IV anesthetics shouldn't be used on pt's with acute intermittent porphyria? | pentothal and brevital |
| Which IV anesthetic causes HTN w/ loading dose? | dexmetetomidine |
| Which IV anesthetics cause excitatory activity? | brevital and etomidate |
| Which IV anesthetic contains and imidazole-containing compound? | etomidate |
| Which IV anesthetic can achieve an isoelectric EEG? | pentothal |
| Which IV anesthetic reduces shivering? | dexmetetomidine/precedex |
Created by:
lindseymontgomery
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