Blood Pressure Goals and Vasoactive Agents

Question 1

Mean arterial Blood pressure (MAP) formula

Answer 1

1/3 SBP + 2/3 DBP

example: 120/80

1/3 (120) + 2/3 (80) = 40 + 53.3 = 93.33 mmHg

how much pressure is in the blood vessels during 1 cycle
-> indicator of blood flow

Question 2

At what MAP do we start using Vasopressors?

Answer 2

less than 65

Question 3

What are conditions that cause hypertension in critical care?

Answer 3

-Hypertensive crisis
-Aneurysmas
-Strokes
-traumatic brain injuries
-thyroid storm
-overdose (methamphetamine, cocaine, bath salts)

Question 4

What are conditions that cause hypotension in critical care?

Answer 4

-Sepsis
-Cardiogenic Shock
-Hypovolemic shock
-Neurologic injuries
-spinal cord injuries
-Drug-induced

Question 5

How is Hypertensive EMERGENCY different from Hypertensive URGENCY?

Answer 5

Hypertensive EMERGENCY comes with signs of end-organ damage

-headache
-Encephalopathy
-Visual changes
-Chest pain
-Acute renal failure
-Dyspnea

Question 6

What BP is associated with Hypertensive Urgency and Emergency?

Answer 6

> 180/120

for Urgency: lower BP slowly (hours to days)

for Emergency: lower MAP by 10-20% in the first hour, then gradually over the next 23 hour

Question 7

Which drugs are used in a Hypertensive Urgency?

Answer 7

oral agents:
-Captopril
-Labetalol
-Clonidine

Question 8

Which drugs are used in a Hypertensive Emergency?

Answer 8

rapidly titrable infusions: linear (predictable) decrease in BP with an increase in dose

CCB
-Nicardipine (often used)
-Clevidipine

drugs like Nitroglycerin have unpredictable BP drops when increasing the dose (may stop perfusion to organs)

Question 9

What causes an ischemic or hemorrhagic stroke?

Answer 9

Ischemic: Emboli blocking blood flow -> cell death

Hemorrhagic: bleeding in the brain leads to swelling (less blood flow to tissue, blood irritates blood vessels)

Question 10

What is a Penumbra?

Answer 10

area around the injured (reversible) brain tissue
-> with ischemic stroke

Question 11

What blood pressure is required for a patient with an ischemic stroke to receive tPA?

Answer 11

<185/<110

Fibrinolytic Goal: keep BP <180/105

Question 12

At what BP are patients with ischemic stroke treated with an antihypertensive if not treated with a tPA?

Answer 12

do not treat unless >220/>120

Question 13

The BP in hemorrhagic stroke is treated more or less aggressively than ischemic stroke? Why?

Answer 13

More aggressive bc we want to prevent further bleeding that is getting worse with increased BP

Question 14

What is the Goal BP in patients with hemorrhagic stroke without evidence of increased intracranial pressure?

Answer 14

MAP 110
SBP <140
BP <160/90

Question 15

What is the goal cerebral perfusion pressure (CPP) in patients with hemorrhagic stroke?

Answer 15

maintain cerebral perfusion pressure CPP at 61-80

Question 16

What is an Aortic Dissection?

Answer 16

A tear in the inner layer of the aorta -> blood flows in and causes rapture

Type A = surgical emergency
Type B = medical treatment

Question 17

What is the Goal BP in patients with an aortic dissection?
!!!

Answer 17

Rapidly reduce BP

SBP <120 (100)
HR <60

Question 18

What is the drug of choice to treat Aortic Dissection?

Answer 18

IV Beta blocker (targets BP and HR)
-esmolol (selective, short-halflife)
-labetalol
-propanolol

may use oral for long-term management later:
-carvedilol

Question 19

MOA of Hydralazine
Unique side effect of Hydrazaline

NAPLEX

Answer 19

Vasodilation of arterioles

Drug-induced lupus syndrome, avoid in coronary artery disease CAD

Question 20

What are the 4 types of shock?

Answer 20

-Obstructive shock
-Distributive shock
-Cardiogenic shock
-Hypovolemic shock

Question 21

What is the Goal SBP and MAP in patients in shock?

Answer 21

SBP: >90 mmHg MAP >65 mmHg

shock: decreased organ perfusion

treat with Vasopressors (Norepinephrine, Epinephrine, Phenylephrine, Dopamine, Vasopressin)

Question 22

What is the function of α and ß receptors?

Answer 22

α-1: Peripheral arteriolar vasoconstriction
ß-1: Increased heart rate and force of contraction
ß-2: Bronchial and skeletal smooth muscle dilation

DA: increased renal blood flow

Question 23

Phenylephrine binds to which receptors and has what effect?

Answer 23

α1 - receptors causing vasoconstriction (increase in BP)

Question 24

Norepinephrine and Epinephrine bind to which receptors and have what effect?

Answer 24

α1 -> vasoconstriction
ß1 -> increased HR and contraction
low ß-2 -> bronchial dilation

Epinephrine is dose-dependent
low dose: ß-receptors
high dose: α-receptors

Question 25

Dopamine binds to which receptors and has what effect?

Answer 25

dose-dependent vasopressor at low dose: ß1 -> increased HR and contraction at high dose: α -> vasoconstriction - increased BP some ß2: bronchial dilation some dopamine receptors: increased renal blood flow

Question 26

Dobutamine binds to which receptors and has what effect?

Answer 26

ß1 -> increased HR and contraction low ß-2 -> bronchial dilation some α it is an inotrope (makes the heart beat harder and faster)

Question 27

Which drug only has ß activity and increases the heart rate but has no effect on BP?

Answer 27

Isoproterenol

Question 28

Which Vasopressor is most commonly used to increase the blood pressure?

Answer 28

Norepinephrine (Levophed) α1-agonist, also ß1

Question 29

Which of the Vasopressors may cause arrhythmias?

Answer 29

Dopamine

Question 30

Which receptors do Ionotropes bind to? Name two Inotropes.

Answer 30

bind to ß-receptors -Dobutamine (ß-agonist) -Milrinone (PDE-3 inhibitor)

Question 31

When would Milrinone be used?

Answer 31

end-stage heart failure -these patients usually use ß-blocker already, so all the ß-receptors are blocked -so induce heart rate by blocking PDE-3

Question 32

Which drug is used as an adjunctive Vasopressor? What are the precautions of this drug?

Answer 32

Vasopressin (Pitressin) -not an adrenergic receptor, it works on Vasopressin receptors -never use as monotherapy !! -don't use in cardiogenic shock !! -not pH dependent !! (other vasopressors need increased doses as pH goes down, they also cut off blood flow to other areas with prolonged use)

Question 33

Which line is used to administer Vasopressin?

Answer 33

mostly requires Central lines it would cause ischemia in peripheral lines

Question 34

Which drugs are used to treat extravasation that causes localized ischemia?

Answer 34

Phentolamine (α1-antagonist -> vasodilation) Terbutaline (ß2 agonist) topical Nitroglycerine (vasodilator)