Lecture # 02 _Fall_IV Anesthetics Flashcards
List the 10 factors of an i
deal anesthetic.
- water soluble and stable
- no pain on injection;no tissue damage w/extravasation
- low incidence of histamine release or hypersensitivity
- rapid smooth onset
- rapid metabolism to inactive metabolites
- steep dose response curve
- minimal cardiac/respiratory depression
- decreases ICP/CMRO2
- rapid smooth recovery
- minimal side effects: PONV, amnesia, HA, dizziness
Are Barbiturates acidic or alkaline?
very alkaline (pH>10)
Intra-arterial injection of _____ ->crystals-> thrombosis, necrosis?
What is the treatment?
thiobarbiturates (thiopental and thioamylal)
Treat: papaverine, lidocaine, stellate ganglion block, heparin
What is the mechanism of action of barbiturates?
depress the RAS (reticular activating system ) - consciousness center in the brain stem
Suppress excitatory neurotransmitters (Ach)
Enhance inhibitory (GABA)
Which of the following is true regarding barbiturates - indicate all that apply
A. water soluble B. stable C. no pain on injection D. no pain on extravasation E. acidic
A. water soluble - T B. stable - F C. no pain on injection - T D. no pain on extravasation - F E. acidic - F
What is the difference between Thiobarbiturates and Oxybarbiturates? Give an example of each.
Thiobarbs (thiopental, thioamylal)
higher lipid solubility->greater potency, rapid onset, shorter duration
Oxybarbs (methohexital)
lower lipid solubility->less potency, slower onset, longer duration
Are barbiturates a good choice for maintenance of anesthesia?
No bc the elimination half-life is 3-12hrs after multiple doses - saturate the peripheral compartments and have slower redistribution
What are the routes of absorption of barbiturates?
IV for GA; rectal/IM for premedication
T or F. Thiopental has high hepatic extraction, perfusion-limited metabolism, and a shorter elimination half life than Methohexital
False. Thiopental has low hepatic extraction, capacity-limited metabolism, and a longer elimination half life than Methohexital
T or F. Methohexital has high hepatic extraction, perfusion-limited metabolism, and a shorter elimination half life than thiopental
T
T or F. 2-4mg/kg/hr of Thiopental can be given for treatment of intracranial HTN or intractable seizures?
T
What is the half-life of Methohexital?
3.9 hrs
What is the half-life of thiopental?
11.6 hrs
T or F. Barbiturates increase BP and decrease HR.
False
Barbiturates decrease BP and increase HR (central vagolytic effect); venous pooling
T or F. CO is maintained with barbiturates except in hypovolemia, CHF, and beta blockade.
True.
CO is maintained with barbiturates except in hypovolemia, CHF, and beta blockade - this leads to very decreased CO and BP
T or F. Barbiturates do not blunt hypercapnic or hypoxic respiratory drive.
False.
T or F. Bronchospasm and laryngospasm are associated with barbiturates.
T
Porphyria is associated with what class of induction agents?
barbiturates
T or F. Barbiturates are anti-epileptics.
T
T or F. Barbiturates decrease CBF and ICP but increase CMRO2.
False. They decrease all and decrease CMRO2 to burst suppression on EEG
T or F. Barbiturates are renal protective bc they increase RBF.
False. They decrease RBF due to hypotension
Which of the following are lipid soluble
A. Barbiturates B. Propofol C. Etomidate D. Ketamine E. Versed
Lipid soluble = Propofol and Etomidate
Which of the following are water soluble
A. Barbiturates B. Propofol C. Etomidate D. Ketamine E. Versed
Barbs, Ketamine, Versed
Which induction agents cause burning on injection?
Propofol and etomidate
Describe Propofol Infusion Syndrome
- lactic acidosis usually after prolonged high dose infusions
- lipemia, rhabdomyolysis, metabolic acidosis, death
T or F. Patients allergic to eggs should not get propofol.
False.
Propofol is emulsion in intralipid (soybean, glycerol, egg lecithin)
Lecithin is from egg yolk and most allergies are to egg white
Which of the following are anti-epileptics?
A. Barbiturates B. Propofol C. Etomidate D. Ketamine E. Versed
A. Barbiturates
B. Propofol
E. Versed
In which of the following groups would higher plasma levels of barbiturates be seen? (choose all that apply)
A. hypovolemic
B. hypoalbuminemia
C. acidosis
D. elderly
All of the above
T or F. Thiopental contains sulfur and therefor may evoke histamine release
True
What acute condition is associated with barbiturates and is characterized by the following:
abd pain, vomiting, neuropathy, weakness, seizures, hallucinations, depression, anxiety, paranoia
cardiac arrhythmias, pain, constipation/diarrhea
Acute porphyria
T or F. Propofol is renally excreted and doses should be decreased for pts with chronic renal failure.
False. It is renally excreted but is not effected by chronic renal failure
When placing a pt on a propofol infusion for GA, what is your target plasma concentration (in mcg/mL)?
4-6 mcg/mL
T or F. Propofol causes hypotension because it decreases SVR, myocardial contractility, and preload.
True
What are 3 ways to prevent pain caused by the burning on injection of propofol?
- Bier Block (lido + tourniquet)
- pre-treat with IV opioid
- mix lido with propofol (to acidify emulsion)
What drug has been associated with abuse and addiction due to its characteristic side effects of euphoria on emergence, intense dreaming and amorous behavior .
propofol
T or F. There is little evidence of tolerance developing with propofol.
True
T or F. One reason propofol is used in MAC cases is because it causes very little depression of upper airway reflexes.
False. causes PROFOUND depression of upper airway reflexes.
Where is etomidate metabolized?
liver (hepatic hydrolysis) and plasma esterases
even if you have no liver, you can metabolize etomidate, just slower
T or F. Myoclonus is a side effect of etomidate.
True
T or F. Etomidate causes minimal respiratory depression.
True
Transient inhibition of cortisol/aldosterone synthesis can be seen after one dose of what induction agent?
etomidate
T or F. Etomidate is a good induction agent in hemodynamically unstable pts because it has minimal CV effects.
True
Dissociative amnesia is associated with which induction agent?
Ketamine. It dissociates the thalamus for the limbic system = “cataleptic state”
Which induction agent has analgesic properties?
Ketamine
What is the mechanism of action of Ketamine?
Inhibition + excitation; NMDA antagonist
What are the routes of absorption for ketamine?
IV and IM
Which IV induction agent is associated with the following:
bronchodilator, salivation, hallucinations, minimal respiratory depression,
Ketamine
T or F. Ketmaine is the drug of choice for neuro cases.
False. It increases CMRO2, CBF, and ICP
T or F. Versed causes respiratory depression.
True
T or F. Versed should be avoided in neuro cases or is seizure patients.
False
What is dependence?
onset of physical or psychological symptoms after reduction in dose
T or F. Patients that are on benzodiazepines may experience withdrawal symptoms that are so severe it can be fatal.
True
What can be given for a benzodiazepine over dose and how does it work?
Flumazenil - high affinity for receptor with minimal activity
T or F. Flumazenil acts as a non-competitive antagonist.
False. It is a competitive antagonist
What is dexmedetomidine?
(Precedex) Highly elective alpha-2 receptor agonist used for sedation.
What are some advantages and disadvantages of Precedex?
Adv: minimal resp depression, calm sedation with rousability, anxiolysis, some analgesia
Disadv: hypotension, bradycardia, expensive
