Vasopressors - Semester 1 Flashcards
Which vasopressor exerts its effect ONLY on alpha receptors?
Phenylephrine
Which vasopressor exerts its effect ONLY on beta receptors?
Isoproterenol
When comparing Norepinephrine and Epinephrine, which one exerts relatively more effect on alpha receptors, with some beta receptor activity?
Norepinephrine
When comparing Norepinephrine and Epinephrine, which one exerts relatively more effect on Beta receptors, with some Alpha receptor activity?
Epinephrine
What is your “go to” Vasopressor in the majority of cases where patients need vasopressor support?
Norepinephrine
Considering Dopamine’s variable effects - which are dose dependent; what are Dopamine’s main effects at LOW doses and which receptors does it primarily work on at LOW doses?
< 5 mcg/min/kg , often referred to as the “renal dose” - primarily Dopamine Receptors - - causes : dilation of renal arteries and related increase in urine output, as well as vasodilation in mesenteric, coronary and intracerebral vasodilation. Overall effect its decrease in SVR (mild) and increase in CO (mild)
If a patient is currently maintaining their BP / MAP but is showing a very low ventricular rate, what Vasopressor might you consider to temporize the situation until definitive management ?
Epinephrine (aBBB) effect are mostly on Beta Receptors - which will increase HR and Inoptropy
Norepinephrine exerts it’s effect on a1, B1 and B2 receptors, with a predominant effect on B receptors. True or False ?
False: it’s primary effect is on alpha receptors, which causes Vasoconstriction and possible increase in CO. It has some minor effect on B1, and NO effect on B2. (Epinephrine, has mostly Beta effects) - - - Main overall effect in increase SVR
Vasopressin’s main physiological effect is :
It works via which receptor?
Increased SVR
via V1 receptor
What are two, somewhat “unique” indications where Vasopressin is often the vasopressor of choice ?
Esophageal Varices
Diabetes Insipidus
a1»B1>B2 is the hierarchy of effect of which Vasopressor?
Norepinephrine
1st line Vasopressors for Distributive Shock
Norepinephrine
It’s main effect is to increase SVR via a1, thereby increasing BP…..it only has relatively minor effects on HR and Inotropy (relative to other choices)
Which vasopressor is considered a “pure alpha” vasopressor ?
Phenylephrine.
Best uses, for distributive shock that is vagally mediated or OD causing peripheral vasodilation……because Phenylephrine acts only on alpha 1 causing vasoconstriction
A patient in cardiogenic shock, particularly with Hypertrophic Cardiomyopathy (HCM) in need of a Vasopressor would likely best benefit from which Vasopressor ?
Phenylephrine.
Acts only on alpha to increase SVR / BP - - - no extra direct work on heart via B1 receptors, as no effect on B1
Also a good answer is Vasopressin, which also does not act on B1, it works on V1 and V2 receptors at renal level to increase water absorption to increase BP
Key potential side effect of Phenylephrine?
Reflex Bradycardia
Symptomatic Bradycardia can be treated with which Vasopressors?
Dopamine - Moderate doses 5-15 mcg/kg/min - increase in CO and SVR
Epinephrine - alpha, and beta - low doses increase CO, higher doses more SVR
Isoproterenol - - beta only, increase HR and Inotropy*** best choice…
What receptor(s) does Dobutamine mainly work on ?
Mostly B1 and B2
What are Dobutamine’s main physiological effects and potential side effects?
B1 - increase HR and Inotropy, leading to increase in CO
B2 - significant vasodilation in muscles / liver (along with bronchodilation and release of insulin) - but causes likely Hypotension…..so not generally a good option - - - can also cause Hypokalemia. (increase in insulin moves more K inside the cell) - - - action is more INODILATION with increase CO
What receptor(s) does Milrinone work on ? What is it’s main action ? Side Effects?
Phosphodiesterase Inhibitor
Improves Perfusion (INODILATOR) - via smooth muscle dilation , decrease in SVR - - main effect is increase CO (re: CPS) used Cardiogenic Shock. cAMP mediated…..
Has risk of Hypotension
Symptomatic Bradycardia, before moving to Pacing…..what are your best drug options ?
Dopamine - part of ACP scope of practice traditionally, but we are trying to stay away from it these days
Atropine could work (but only if there isn’t a block at AV node, as it is a parasympatholytic (opposes PSNS) that works only at SA and AV to increase chronotropy….also a standard of care in ACP scope of practice
Epi - push or drip is a good option….works both alpha (vasoconstriction) and Beta (chronotropy) and is not limited in cases of AV blocks!
What is “Dirty Epi”? What might you use it for ?
Dirty Epi = 1 mg in 1 L (shake well) - - - that’s either 1mg of 1:1000, or 1mg of 1:10000 into the 1 L bag, but 1:1000 better due to volume. That creates a concentration of 1mg / 1 L ……otherwise known as 1mg /1000 mL - - - -> 0.01 mcg/mL
Might use it for a patient that needs very quick intervention while waiting for the standard drip of NE to be set up (which can take time)….could use it in Symptomatic Bradycardia…..or for other causes of concerning hypotension (septic, distributive, other) - - - but because it has way more effect on Beta than NE (epi = aBBB; NE = aaaB) - - -consider stress on heart say in cases of evolving MI etc…
What is the standard mix of an Epi Drip ? What’s the dose to deliver via infusion ?
4 mg of Epi in 250 mL D5W, = 4000 mcg / 250 mL = 16mcg/mL (which is the same concentration you want for NE drip).
You want to run at 0.01 - 1.0 mcg/kg/min
Say 0.5 mcg/min for 70 kg - - - > 35mcg/min
gtts/min = ((35 x 10) / 1) = 350 gtts/ min (that won’t work!) - - - so let’s say 0.01 mg - - x 70 = 0.7mcg/min
try again : gtts/min ((0.7 x 10)/1) = 70 gtts per min - - - low, but a good starting point, won’t work for “bigger patients” (too low)
Consider about 120 gtts/min - - - to cover all weights at a low to medium dose…..
120 gtt/min = ((X x 10))/1 - - - > (120 x 1) / 10 = 12 mcg/min
12mcg/min divide by 60 kg
by 70 kg
by 80 kg
by 90 kg
by 100 kg
What is the standard mix of an Epi Drip ? What’s the dose to deliver via infusion ?
4 mg of Epi in 250 mL D5W, = 4000 mcg / 250 mL = 16mcg/mL (which is the same concentration you want for NE drip).
You want to run at 0.01 - 1.0 mcg/kg/min
Say 0.5 mcg/min for 70 kg - - - > 35mcg/min
gtts/min = ((35 x 10) / 1) = 350 gtts/ min (that won’t work!) - - - so let’s say 0.01 mg - - x 70 = 0.7mcg/min
try again : gtts/min ((0.7 x 10)/1) = 70 gtts per min - - - low, but a good starting point, won’t work for “bigger patients” (too low)
Consider about 120 gtts/min - - - to cover all weights at a low to medium dose…..
120 gtt/min = ((X x 10))/1 - - - > (120 x 1) / 10 = 12 mcg/min
12mcg/min divide by 60 kg = 0.2 mcg/kg/min
by 70 kg = 0.17
by 80 kg = 0.15
by 90 kg = 0.13
by 100 kg = 0.12
by 110 kg = 0.109 ………..so all of these doses fall within range on the lower side, but countable gtts, realistically you’ll just set a pump.
You “should also get comfortable with Push Dose Epi” (when waiting for NE drip to be set up)……
How do you prepare it ? How would you deliver it ?
Aside from making up Epi Drip (4mg in 250 D5W = 16 mcg/mL ; given 0.01 to 1.0 mcg/kg/min) you can also consider Push Dose Epi for a really quick fix in an emergency. (Patch, discuss on way to call as option)
2 options: 1) 1 mg EPI + 9 NS in syringe = 1mg/10mL = 1000 mcg/10 mL = 100 mcg/ 1mL
DOSING: say, 100 kg = 1.0 mcg/kg/min = 1 mL over 1 min - slow push
say 80 kg = 1.0 mcg/kg/min = 0.8 mL over 1 min - slow push
2) 1 mg EPI into 100 cc Bag NS = 1mg/100mL = 1000 mcg/100 mL = 10 mcg/mL
DOSING: say , 100 kg @ 1.0 mcg/kg/min = 100 mcg/min = 10 mL / min - (drawn from bag, given slow push)
say , 100 kg @ 0.5 mcg/kg/min = 50 mcg/min = 5 mL / min
For other weights - - - say 80 kg, @ 1mcg/kg/min = 8mL/min.......which would make 0.5 mcg/kg/min = 4mL/min
Putting it in bag, is better (and safer) - easier volumes to push accurately and can easily do math in head to hit mid and
and High dose.
