ICU and Inj Anestetics Flashcards
What conditions cause an increase in volume of distribution?
Anything that results in distributive shock: Sepsis, heat stroke, anaphlaxis,
Inhalant anestesia - also causes vasodilation
(Increased volume distribution = more space for drugs to spread out in)
What conditions cause a decrease in volume of distribution?
Anything that results in hypovolemia or shunting of blood: Hemorrhage, surgical procedures,
How does blood volume affect liposoluble drugs vs hydrosoluble drugs?
Liposoluble drugs will accumulate in fatty tissue, and so its volume of distribution is not affected by blood volume.
Hydrosoluble drugs’ volume of distribution is highly affected by blood volume
What conditions can cause increased drug effects due to increased free drug in circulation?
Anything that results in hypoprotinemia: Ascites, protein losing nephropathy, protein loss in diarrhea, increased vascular permeability
How does redistribution affect injectable anesthetics?
Anestetic duration is mainly affected by redistribution and not clearance rate
When does metabolism play a role in anesthesia if at all?
Metabolism and clearance only affects anestetic time if the drug is given as a CRI
What is the general mechanism of action for injectable anestetics?
Stimulation of GABA receptors to promote functional inhibition
Thiopental
Barbituate that acts as GABA agonist at high doses, and GABA enhancer at low // Liposoluble // Cleared very slowly by CP450 liver enzyme // Good drug to prevent intracranial pressure
Propfol
Non-barbituate GABA modulator // High lipid vehicle - don’t use in pancreatitis or hepatic lipidosis // Can cause oxidative damage in cat RBCs if used too much
Etomidate
Non-barbituate GABA agonist // Interferes with synthesis of glucocorticoids // Can cause muscle rigidity // No cardiac effects! (Give heart a break)
Ketamine
Non-competitive NMDA antagonist // Causes vasoconstriction and inotropic effects - contraindicated in heart disease // Apneuistic breathing (breath holding)
