IV anesthesia Flashcards
All IV anesthetics are lipophillic which means they suck for injections
pH can be adjusted or a surfactant added to make them suitable for IV. Some are now in prodrug form.
Beware that surfactants can lead to thrombophlebitis when given too quickly
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All IV anesthetics do what?
potentiate GABA and Glycine
Remember that Ketamine and Propofol also inhibit Glutamate. Propofolol blocks the binding of glutamate to its receptors whereas ketamine physically occludes the channel
Which of the induction agents is capable of acting just like GABA itself at high concentrations
propofol
Two pathways of the ascending arousal system
The cholinergic cell groups in the upper pons, the pedunculopontine (PPT) and laterodorsal tegmental nuclei (LDT) send signals to the THalamus
Second pathway activates the cerebral cortex. Arises from the tuberomamillary nucleus (histamine), A10 (dopamine), and dorsal and median raphe nuclei containing serotonin, and Locus ceruleus containing noradrenaline
What do barbiturates do to reinforce the inhibitory actions of GABA in the CNS?
Prolong the binding of GABA to the receptor, which increases the strength of the inhibitory effects on endogenous GABA
Benzodiaepines simply shift the dose response curve to the left and therefore increase the potency but not the efficacy of GABA where barbiturates increase both.
Barbiturates produce greater and greater CNS depression whereas benzos taper off
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IV anethetics rapidly distribute out of the plasma and into high flow organs and then over time redistribute to other organs and eventually adipose tissue.
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What is the rate limiting step in the final elimination of anesthetics following surgery
Release from adipose tissue
Know the theory of context dependent half-lives
Some drugs have half-lives that increase with longer infusion times, anesthesiologists will back off of these before the surgery is over.
Of the parenteral anesthetics, which is the only one that increases Cerebral blood flow and ICP (the rest lower it)
Ketamine
Thiopental, Ketamine and Propofolol have what effect on the heart
slight stimulatory effect
Remember to keep in mind that propofolol has anti-emetic properties which may make it attractive when performing a surgery
BUT
ALso remember that it may cause Propofol infusion syndrome which leads to fatal CV effects
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What’s bad about Etomidate?
inhibits steroidgogenesis…reductions in cortisol observed after just a single dose
Weird things about Ketamine
It is structurally similar to angel dust…It has nalagesic actions, preserves protective refelxes, produces hallucinations.
ALso preserves respiratory function and as we saw earlier, doesn’t negative effect CBF, ICP, is cardiostimulatory and inc CO
