Hemodynamic Drugs Flashcards
What do beta 1 receptors do?
Cardio acceleration
Increase contractile they
Lipgloss
What do beta 2 receptors do?
Vasodilation
Bronchodilator
Increased glycolysis
Uterine relaxation
What receptors does dobutamine act on?
Beta 1>beta 2
What happens to systemic vascular resistance when you use dobutamine?
It decreases due to weak beta 2 activity
What happens to cardiac output when you use dobutamine?
Increases
What condition is dobutamine used for?
Myocardial depression after septic shock
What is the infusion rate of dobutamine?
3-5 micrograms/kg/min
Increase in increments of 3-5 micrograms/kg/min
In what heart condition is dobutamine contraindicated?
Hypertrophic cardiomyopathy
What receptors does dopamine act on in moderate dose?
Beta 1 and 2
What receptors does dopamine act on in high doses?
Alpha and beta 1/2
What is the low infusion rates of dopamine?
3 micrograms/kg/min
Which organ circulations does dopamine act on at low rates?
Renal and splanchnic
What is the effect of low infusion dopamine on renal and splanchnic circulation?
Increased sodium excretion
Increases blood flor to these regions
What organs are affected with moderate infusion of dopamine?
Beta 1 in the heart and beta 2 in the periphery causing increase heart rate and contractility with vasodilation
What is a moderate infusion rate of dopamine?
3-10 micrograms/kg/min
What is a high dopamine infusion rate?
Greater than 10
What are the effects of a high dopamine rate?
Alpha - vasoconstriction
Why does dopamine have to be administered into a large central vein?
Because extravasation from a peripheral vessel cause extensive tissue necrosis
What are the adverse effects of dopamine?
- Sinus tachycardia and afib (25%) of patients
- Increased intraocular pressure
- Splanchnic hypoperfusion
- Delayed gastric emptying
What drug should you inject if you get extravasation of a vasoconstrictor?
Phentolamine - alpha antagonist
What organ releases epinephrine?
Adrenal medulla
What drug is a more potent beta 1 agonist than dopamine?
Epinephrine
What receptors does epinephrine act on?
All of them
What is epinephrine used for?
Cardiac arrest
Postop cabg
What is the infusion of epinephrine started at?
1-2 micrograms/kg/min
What is the usual dose range for epinephrine for augmenting cardiac output or correcting hypotension?
5-15 micrograms/kg/min
What are the other effects of epinephrine?
- Hyperglycemia
- Increased metabolic rate
- Splanchnic vasoconstriction
- Increased lactate (because increases the rate of glycolysis thru beta 2 effects)
What is the preferred drug for septic shock and why?
Norepinephrine because it has fewer side effects than dopamine or epinephrine
What are norepinephrine infusions usually started at?
8-10 micrograms/min
What receptors does norepinephrine work on?
Alpha 1 Beta 1 (weak)
What are the effects of using norepinephrine in a patient with septic shock?
Increased renal and splanchnic blood flow (paradoxical)
What phenylephrine cause?
Systemic vasoconstriction with reflex bradycardia
What is the principal use of phenylephrine?
Reversal of severe hypotension produced by spinal anesthesia
How much phenylephrine do you initially give someone?
0.2 mg
What is the max dose of phenylephrine?
0.5 mg
What does vasopressin do?
V1 - causes vasoconstriction in the skin, skeletal muscle and splanchnics
V2 - increases water resorption in the distal renal tubules
V3 - causes ACTH release by anterior pituitary
What is vasopressin used in?
In cardiac arrest (40 units)
Septic shock that is refractory to norepinephrine or dopamine to raise bp and reduce the catecholamine requirement
In cases of hemorrhagic get varices to promote splanchnic constriction
What is the half life of vasopressin?
5-20 minutes
What is the infusion rat of vasopressin?
0.03 units/he
What is terlipressin?
Vasopressin analogue that is V1 receptor selective and has a longer duration of action
What is the duration of action of terlipressin?
5 hours
What is the danger of terlipressin?
Splanchnic ischemia
What does nitroglycerin do?
Binds to the surface of endothelial cells and releases inorganic nitrite which is converted to NO which promotes cGMP and cause muscle relaxation
- venodilation at lower infusion rates
It also inhibits platelet aggregation
Why does nitroglycerin have to be in a glass bottle of PET tubing?
Because it binds to polyvinylchloride plastics
What is the initial infusion rate of nitroglycerin?
5-10 micrograms/min
What are the adverse effects of nitroglycerin?
Right heart infarction
Increased cerebral blood flow –> increased ICP
Increased pulmonary blood flow –> physiologic shunt
Methemoglobinemia
Solvent toxicity
What solvents must be used to keep nitroglycerin dissolved?
Ethanol
Propylene glycol
How can you prevent nitrate tolerance?
6 hours a day drug free
How does nitroprusside work?
It releases NO when it enters the blood
What is nitroprusside better at?
Arterial dilation
What is nitroprusside used for?
Hypertensive emergency
Decompensated heart failure
How is cyanide cleared from the body?
Thiosulfate gives a sulfur group to cyanide and then this thiocyanate is cleared by the kidneys
Cyanide binds to the oxidized iron in methemoglobin
How much thiosulfate should be given for 50 mg of nitroprusside?
500 mg
What is the first sign of cyanide toxicity in nitroprusside infusion?
Increasing nitroprusside requirement
What are the signs of thiocyanate toxicity?
Anxiety, confusion, seizure, miosis, tinnitus, hallucinations, hypothyroidism
What is the diagnostic level for thiocyanate toxicity?
Above 100
What is the treatment for thiocyanate toxicity?
Dialysis
What do alpha receptors do?
- Vasoconstriction
- Iris dilatation
- Piloerection
What does dopamine do to TSH?
Inhibits its release from the pituitary
What does dopamine do to T cell function?
Inhibits their function
What is the MOA of methylene blue?
Inhibits nitric oxide synthase and cGMP counteracting refractory hypotension from vasoplegia from endothelial dysfunction
