CV Drugs Flashcards
What are the classes of drugs that have effects on the heart?
Anticholinergics
Antiarrhythmics
Vasopressors/Iontropes
What are two types of Vasopressors/Iontropes?
Adrenergic agonists
Vasopressin
What is the ultimate goal of CV drugs?
Oxygen delivery to the tissues
DO2
Oxygen Delivery to Tissues
What is DO2 dependent on?
Cardiac Output
Blood O2 content (CaO2)
CaO2
Blood O2 content
What is the equation for DO2?
CO x CaO2
What is the equation for CO?
Heart Rate X Stroke Volume
What are the targets for CV drugs?
Heart Rate
Contractility
Afterload/Preload
What drugs affect Heart rate?
Anticholinergics
Antiarrhythmics
What are drugs that effect Contractility?
Inotropes
What are drugs that effect Afterload/Preload?
Pressors
What is the definition of Anticholinergics?
Competitive antagonists at the muscarinic Ach receptors
What drugs antagonize Nicotinic Ach receptors?
Neuromuscular Blockers
What kind of drugs decrease parasympathetic tone?
parasympatholytics
What is the effect of Anticholinergics?
Decreases Parasympathetic tone
Increased firing of the SA node (chronotropy) and conduction speed through the AV node (dromotopy)
Where are M1 receptors located?
CNS
Stomach
Where are M2 receptors located?
Heart
CNS
airway smooth muscle
What do M2 receptors cause?
bradycardia
Where are M3 receptors located?
CNS
salivary glands
airway smooth muscle
Where are M4 receptors located?
CNS
Heart
Where are M5 receptors located?
CNS
What do M3 receptors cause?
Salivation
bronchodilation
vasodilation
When are anticholinergics indicated?
Bradycardia secondary to increased vagal tone
What increases vagal tone?
Intubation vomiting manipulation of ophthalmic GI Hepatobiliary structures Opioids Brachycephalic conformation
What are the side effects of anticholinergics?
Increased viscosity of saliva Ileus and colic decreased LES pressure sedation bronchodilation mydriasis
When is atropine contraindicated?
glaucoma
What species are the used of anticholinergics cause for concern?
Horses
Ruminants
What are the CNS side effects of anticholinergics?
Sedation
What are the respiratory side effects of anticholinergics?
bronchodilation
What are the Ophthalmic side effects of anticholinergics?
mydriasis
Paradoxical Bradycardia
due to blockade of presynaptic inhibitory M1 receptors on vagus
inhibition of inhibitory receptors leads to increased Ach release
What is a Class 1B Anti arrhythmic?
Lidocaine
What are Class II Anti-arrhythmics?
Beta Blockers
When are beta blockers used?
severe sinus or supraventricular tachycardia
When do you use Beta Blockers in anesthesia?
tachycardia associated with pheochromocytoma
What is the most common beta blocker used?
Esmolol
What happens when alpha 1 and alpha 2 receptors are activated?
vasoconstriction
What does Beta 1 on the heart cause?
Increased Inotropy and chronotropy
What does beta 2 on the blood vessels and bronchi cause?
Vasodilation and bronchodilation
What does alpha overstimulation cause?
Vasoconstriction
Decreased perfusion
increased cardiac workload
What does beta 1 overstimulation cause?
tachyarrhythmia
increased myocardial O2 demand
What does beta 2 overstimulation cause?
vasodilation
decreased pre load
What drugs act on mixed receptors?
Dopamine
Ephedrine
Norepinephrine
Epinephrine
What drug acts primarily on alpha receptors?
Phenylephrine
What drugs act primarily on beta receptors?
Dobutamine
Isoproterenol
What drug acts on non-adrenergic receptors?
Vasopressin
What receptors does Dopamine act on with low doses?
Dopamine receptors
What receptors does Dopamine act on with medium doses?
Beta receptors
What receptors does Dopamine act on with high doses?
Beta and alpha receptors
What can ephedrine cause?
Reflex bradycardia
CNS stimulation
What is norepinephrine indicated in?
refractory shock or non-responsive hypotension
What is epinephrine indicated in?
CPR
Anaphylactic shock
What kind of agonist is Phenylephrine?
Alpha 1
What does phenylephrine cause?
Splenic contraction
What is phenylephrine used to treat?
nephrosplenic entrapment
What receptor does Dobutamine act on?
Beta 1
What does Dobutamine cause?
Increased inotropy
minimal effects on chronotropy
What receptor does Isoproterenol act on?
Beta 1 and B2
What is Isoproterenol used for?
treatment of 3rd degree AV block and bronchodilation
Vasopressin
Antidiuretic hormone
When is Vasopressin indicated?
Refractory shock
non-responsive hypotension
What does Vasopressin cause?
Vasoconstriction
Tissue Ischemia
What is the first thing to do for hypotension?
evaluate patient and turn down the vaporizer if the patient is too deep
If the patient is too light ass mac-sparing drug then turn down the vaporizer
What are other strategies for hypotension?
Give crystalloid fluid bolus
Treat the suspected underlying cause
consider CV drug therapy
How do you treat Vasodilation?
Give Vasopressor
How do you treat decreased contractility?
Give Inotrope