IV Anesthetics Flashcards
Name some barbiturates.
thiopental, methohexital, thiamylal
What properties does thiopental provide?
anticonvulsant and amnestic properties, but POOR analgesic—-> in small doses may be hyperalgesic
What negative properties does thiopental have?
depresses respiratory system, depresses myocardial contractility (decreasing SV, CO, and BP with reflexive increase in HR)
What effect does thiopental have on cerebral blood flow?
increases cerebral vascular resistance—> decreasing cerebral blood flow and ICP
What condition may increase the patients response to thiopental?
hypoproteinemia (hypoalbuminemia); thiopental is largely protein bound in plasma
What are two types of patient conditions in which you should avoid the use of thiopental?
1) asthmatic–> due to possible histamine release
2) porphyria–> disease caused by inadequate porphyrin metabolism (contributes to heme precursors)
What is the half-time of propofol?
0.5-1.5 hours (more rapid and complete awakening than other IV anesthetics)
What are some positive and negative characteristics of propofol?
\+= more rapid and complete awakening, good antiemetic d\t it's action on the chemoreceptor trigger zone in the brainstem and vomiting center, anticonvulsant properties -= depressed CO and SVR, HR is often unchanged, profound ventilatory depressant in comparison to thiopental, no analgesic properties
What effect does propofol have on cerebral blood flow?
decreases CBF and CMRO2
How do benzodiazepines work?
by enhancing the action of GABA (the brain’s major inhibitory neurotransmitter)
Name 3 short acting benzos.
diazepam, lorazepam, midazolam
What effect on the heart do benzos have?
minimal–> unless patient is volume depleted, in which profound hypotension can occur
What are some of the CNS actions of benzos?
antianxiety, amnestic, sedative, hypnotic, and anticonvulsant; muscle relaxation is also produced; POOR analgesics
What effect do benzos have on cerebral blood flow?
cause cerebral vasoconstriction–> lowering CBF and ICP
Why can pain occur with administration of diazepam?
poorly H2O soluble, it is dissolved in an organic solvent
Diazepam is _____% protein bound.
98-99%
Ketamine produces ________ anesthesia.
dissociative
Ketamine produces amnesia and profound analgesia by interacting with the _______ receptor.
NMDA-type glutamate
Name some of the effects of Ketamine.
cerebral vascular dilator (CBF and ICP INCREASE), increases CMRO2, causes hypertonus and nystagmus, stimulates SNS (increases HR, CO, and BP)
What type of patients are ideal candidates for Ketamine?
poor risk patients (trauma, elderly)
Name 3 types of patients to AVOID Ketamine usage.
1) cardiac patients (ex-CAD)–> stress em dead
2) glaucoma patients (IOP increased)
3) patients with elevated ICP
How is emergence of a patient that received ketamine?
Oh Joy–> dreams, hallucinations, n/v
Is Ketamine a weak acid or base?
weak base with a pKa of 3.5-5.0–> do not mix with alkaline solutions to avoid precipitate
What are some side effects of synthetic opioids?
profound respiratory depressant, promotes cardiac stability (slight bradycardia may occur), excellent analgesia, promotes n/v due to stimulation of chemoreceptor trigger zone, acts centrally to stimulate vagal nerve thus promoting bradycardia, truncal rigidity, promote cerebral vasoconstriction and decreased CBF and decreased ICP so long as ventilation is controlled–> if not build up of CO2 dilates cerebral vasculature
What effect do opioids have on the biliary tract?
cause the sphincter of Oddi to spasm (controls release of digestive juices into the second part of the duodenum)–> pressure in the biliary tract increases
Tx= glucagon 1-2mg IM–> relaxes the sphincter
What is an effect specific to morphine that can decrease SVR and BP? What types of patients should this be avoided in?
morphine; asthmatics
What is the “safest” IV anesthetic to use for cardiovascular instability?
Etomidate
What is a s\e that is specific to Etomidate in comparison to other IV anesthetics?
directly depresses cortisol output from the adrenal cortex; depresses immune system
The CNS effects after bolus injection of an IV anesthetic are terminated primarily by _________.
redistribution
