Circulation

Question 1

Major categories of shock

Answer 1

1. Hypovolemia
2. Cardiogenic
3. Obstructive
4. Distributive

Question 2

Bedside assessment of shock? How is BP determined

Answer 2

BP = SVR x (HR x SV)
(CO = SV x HR)
Feel patient’s extremities - if warm, vasodilated SVR is low. If cool, mottled SVR is high
If BP low, SVR high then CO must be low - need to determine HR/SV
Look at HR - too fast or slow
SV - check JVP
Rule out obstructive causes of low SV (tamponade, tension pneumo, massive PE)
If low JVP and low SV need volume first (fluid vs. blood)
If volume and obstruction are not the issue -think contractility

Question 3

What is the mechanism and dosing of dobuatmine?

Answer 3

Mechanism: inotrope, works on B1 cardiac receptors
Dosing: 2-20 mcg/kg/min
Caution: may cause tachydysrhythmias, cardiac ischemia from increased demand

Question 4

Mechanism of norepinephrine? Dosing?

Answer 4

Mostly alpha agonist, some B1 activity.
Useful as a vasopressor in wide variety of situations
Less reflexive bradycardia compared to phenylephrine due to beta activity
0.01-0.5 mcg/kg/min, once you hit >0.3-0.4 with no improvement always think about other causes of shock

Question 5

Mechanism of phenylephrine? Dosing?

Answer 5

Alpha 1 agonist
Vasopressor only, no inotropy
Short acting, easy pocket pressor
50-200 mcg IV q5 min as needed

Question 6

Mechanism of dobutamine?

Answer 6

B1 agonist
Inotrope
Also induces some vasodilation with B2 activity
Risk of tachydysrhythmias

Question 7

Mechanism of milrinone?

Answer 7

Phosphodiesterase (PDE3) inhibitor, inodilator
acts on increasing cAMP to increase intracellular calcium levels
In cardiac cells - leads to increase inotropy and contractility
In peripheral vasoactive cells - leads to vasodilation
Watch for hypotension
Long acting, increased in renal failure - difficult to “take back” once started

Question 8

Differentiate between systolic and diastolic dysfunction

Answer 8

Systolic dysfunction: poor contractility of myocardium, decreased stroke volume

Diastolic dysfunction: Preserved systolic function, but decreased ventricular compliance and relaxation
End diastolic pressure increases with little improvement in end diastolic volumes (SV). Reduces pressure gradient for flow into the ventricles, leads to decreased cardiac output

Question 9

10 major causes of AV block

Answer 9

1. Ischemia
2. Fibrosis/sclerosis of conduction system
3. Medications - amiodarone, adenosine, beta-blockers, calcium channel blockers, clonidine, digoxin
4. Hyperkalemia
5. cardiomyopathy
6. myopericarditis
7. Hyper/hypothyroidism
8. . Infiltrative diseases (rheum, amyloid, malignancy)
9. Trauma
10. Cardiac surgery

Question 10

What forces contribute to ventricular afterload?

Answer 10

End diastolic volume (chamber radius)
Vascular resistance
Vascular compliance
Pleural pressure

Question 11

What are 5 indications for plasma transfusion

Answer 11

1. Clinically significant bleeding in patients with severe liver disease and increased INR/PTT
2. Massive transfusion
3. DIC with active bleeding
4. TTP
5. Patients with coagulation factor deficiencies when factor concentrates are ineffective/unavailable

Question 12

What is the INR of FFP?

Answer 12

1.4-1.5

Question 13

What are 3 indications for cryoprecipitate?

Answer 13

1. Hypofibrinogenemia (s disease

Question 14

What 3 components are involved in hemostasis?

Answer 14

1. Vessels
2. Platelets
3. Coagulation factors