Vasopressors - Semester 1

Question 1

Which vasopressor exerts its effect ONLY on alpha receptors?

Answer 1

Phenylephrine

Question 2

Which vasopressor exerts its effect ONLY on beta receptors?

Answer 2

Isoproterenol

Question 3

When comparing Norepinephrine and Epinephrine, which one exerts relatively more effect on alpha receptors, with some beta receptor activity?

Answer 3

Norepinephrine

Question 4

When comparing Norepinephrine and Epinephrine, which one exerts relatively more effect on Beta receptors, with some Alpha receptor activity?

Answer 4

Epinephrine

Question 5

What is your “go to” Vasopressor in the majority of cases where patients need vasopressor support?

Answer 5

Norepinephrine

Question 6

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?

Answer 6

< 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)

Question 7

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 ?

Answer 7

Epinephrine (aBBB) effect are mostly on Beta Receptors - which will increase HR and Inoptropy

Question 8

Norepinephrine exerts it’s effect on a1, B1 and B2 receptors, with a predominant effect on B receptors. True or False ?

Answer 8

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

Question 9

Vasopressin’s main physiological effect is :

It works via which receptor?

Answer 9

Increased SVR

via V1 receptor

Question 10

What are two, somewhat “unique” indications where Vasopressin is often the vasopressor of choice ?

Answer 10

Esophageal Varices

Diabetes Insipidus

Question 11

a1»B1>B2 is the hierarchy of effect of which Vasopressor?

Answer 11

Norepinephrine

Question 12

1st line Vasopressors for Distributive Shock

Answer 12

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)

Question 13

Which vasopressor is considered a “pure alpha” vasopressor ?

Answer 13

Phenylephrine.

Best uses, for distributive shock that is vagally mediated or OD causing peripheral vasodilation……because Phenylephrine acts only on alpha 1 causing vasoconstriction

Question 14

A patient in cardiogenic shock, particularly with Hypertrophic Cardiomyopathy (HCM) in need of a Vasopressor would likely best benefit from which Vasopressor ?

Answer 14

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

Question 15

Key potential side effect of Phenylephrine?

Answer 15

Reflex Bradycardia

Question 16

Symptomatic Bradycardia can be treated with which Vasopressors?

Answer 16

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…

Question 17

What receptor(s) does Dobutamine mainly work on ?

Answer 17

Mostly B1 and B2

Question 18

What are Dobutamine’s main physiological effects and potential side effects?

Answer 18

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

Question 19

What receptor(s) does Milrinone work on ? What is it’s main action ? Side Effects?

Answer 19

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

Question 20

Symptomatic Bradycardia, before moving to Pacing…..what are your best drug options ?

Answer 20

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!

Question 21

What is “Dirty Epi”? What might you use it for ?

Answer 21

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…

Question 22

What is the standard mix of an Epi Drip ? What’s the dose to deliver via infusion ?

Answer 22

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

Question 23

What is the standard mix of an Epi Drip ? What’s the dose to deliver via infusion ?

Answer 23

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.

Question 24

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 ?

Answer 24

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.