Blood Pressure Goals and Vasoactive Agents Flashcards
Mean arterial Blood pressure (MAP) formula
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
At what MAP do we start using Vasopressors?
less than 65
What are conditions that cause hypertension in critical care?
-Hypertensive crisis
-Aneurysmas
-Strokes
-traumatic brain injuries
-thyroid storm
-overdose (methamphetamine, cocaine, bath salts)
What are conditions that cause hypotension in critical care?
-Sepsis
-Cardiogenic Shock
-Hypovolemic shock
-Neurologic injuries
-spinal cord injuries
-Drug-induced
How is Hypertensive EMERGENCY different from Hypertensive URGENCY?
Hypertensive EMERGENCY comes with signs of end-organ damage
-headache
-Encephalopathy
-Visual changes
-Chest pain
-Acute renal failure
-Dyspnea
What BP is associated with Hypertensive Urgency and Emergency?
> 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
Which drugs are used in a Hypertensive Urgency?
oral agents:
-Captopril
-Labetalol
-Clonidine
Which drugs are used in a Hypertensive Emergency?
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)
What causes an ischemic or hemorrhagic stroke?
Ischemic: Emboli blocking blood flow -> cell death
Hemorrhagic: bleeding in the brain leads to swelling (less blood flow to tissue, blood irritates blood vessels)
What is a Penumbra?
area around the injured (reversible) brain tissue
-> with ischemic stroke
What blood pressure is required for a patient with an ischemic stroke to receive tPA?
<185/<110
Fibrinolytic Goal: keep BP <180/105
At what BP are patients with ischemic stroke treated with an antihypertensive if not treated with a tPA?
do not treat unless >220/>120
The BP in hemorrhagic stroke is treated more or less aggressively than ischemic stroke? Why?
More aggressive bc we want to prevent further bleeding that is getting worse with increased BP
What is the Goal BP in patients with hemorrhagic stroke without evidence of increased intracranial pressure?
MAP 110
SBP <140
BP <160/90
What is the goal cerebral perfusion pressure (CPP) in patients with hemorrhagic stroke?
maintain cerebral perfusion pressure CPP at 61-80
What is an Aortic Dissection?
A tear in the inner layer of the aorta -> blood flows in and causes rapture
Type A = surgical emergency
Type B = medical treatment
What is the Goal BP in patients with an aortic dissection?
!!!
Rapidly reduce BP
SBP <120 (100)
HR <60
What is the drug of choice to treat Aortic Dissection?
IV Beta blocker (targets BP and HR)
-esmolol (selective, short-halflife)
-labetalol
-propanolol
may use oral for long-term management later:
-carvedilol
MOA of Hydralazine
Unique side effect of Hydrazaline
NAPLEX
Vasodilation of arterioles
Drug-induced lupus syndrome, avoid in coronary artery disease CAD
What are the 4 types of shock?
-Obstructive shock
-Distributive shock
-Cardiogenic shock
-Hypovolemic shock
What is the Goal SBP and MAP in patients in shock?
SBP: >90 mmHg MAP >65 mmHg
shock: decreased organ perfusion
treat with Vasopressors (Norepinephrine, Epinephrine, Phenylephrine, Dopamine, Vasopressin)
What is the function of α and ß receptors?
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
Phenylephrine binds to which receptors and has what effect?
α1 - receptors causing vasoconstriction (increase in BP)
Norepinephrine and Epinephrine bind to which receptors and have what effect?
α1 -> vasoconstriction
ß1 -> increased HR and contraction
low ß-2 -> bronchial dilation
Epinephrine is dose-dependent
low dose: ß-receptors
high dose: α-receptors
Dopamine binds to which receptors and has what effect?
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
Dobutamine binds to which receptors and has what effect?
ß1 -> increased HR and contraction
low ß-2 -> bronchial dilation
some α
it is an inotrope (makes the heart beat harder and faster)
Which drug only has ß activity and increases the heart rate but has no effect on BP?
Isoproterenol
Which Vasopressor is most commonly used to increase the blood pressure?
Norepinephrine (Levophed)
α1-agonist, also ß1
Which of the Vasopressors may cause arrhythmias?
Dopamine
Which receptors do Ionotropes bind to?
Name two Inotropes.
bind to ß-receptors
-Dobutamine (ß-agonist)
-Milrinone (PDE-3 inhibitor)
When would Milrinone be used?
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
Which drug is used as an adjunctive Vasopressor?
What are the precautions of this drug?
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)
Which line is used to administer Vasopressin?
mostly requires Central lines
it would cause ischemia in peripheral lines
Which drugs are used to treat extravasation that causes localized ischemia?
Phentolamine (α1-antagonist -> vasodilation)
Terbutaline (ß2 agonist)
topical Nitroglycerine (vasodilator)
