Cardiac 02: Hemodynamic Definitions and Equations Flashcards
Cardiac Output=
HR X Stroke Volume
Stroke Volume is affected by what 3 characteristics?
- Preload
- Afterload
- Contractility
What is the preload?
Total volume of blood in the ventricle at the end of diastole
!!! RV measured by CVP, what are the normal values?
CVP 2-6 mmHg
!!! LV is measured by PAOP, what are normal values?
Pulmonary Artery Occlusion Pressure 4-12 mmHg
What is the Afterload?
The pressure/resistance the LV must contract against or overcome to eject blood/create systole
What is the preload affected by?(2)
- Total Blood Volume
- Venous Tone
What is afterload affected by? (2)
- Arterial Tone
- Arterial Constriction/Dilation
!!SVR Equation!!
System Vascular Resistance
SVR= ((MAP-RAP)x80)/CO
SVR normal values
900-1400 dynes/sec/cm^(-5)
4 factors that could contribute to decreased preload
- Hypovolemia
- Arrhythmia
- Loss of Atrial Kick
- Venous Vasodilation
What causes an increase in preload?
- LV/ RV dysfunction
- Increased Pulmonary Vascular Resistance
- Volume overload
- Cardiac Tamponade/Effusion
- Decreased compliance of any kind
- MV, AV Disease
What can cause a decrease in afterload?
Anything that may cause vasodilation i.e sepsis, or vasodilator therapies
What may cause an increase in afterload?
R heart: pulmonary HTN, hypoxemia, pulmonic stenosis
L heart: vasopressors, vasoconstriction, hypothermia, aortic stenosis
What could cause decreased contractility? (5)
- Parasympathetic Stimulation
- Negative Intropic Therapies
- Beta BLockers
- Calcium Channel Blockers
- Metabolic States: hyperkalemia, MI, acidosis
What could cause increased contractility? (3)
- Sympathetic Stimulation
- Inotropic Therapies
- Metabolic State: hypercalcemia
List 4 Inotropic medications that could increase contractility
- Epinephrine
- Dopamine
- Digoxin
- Calcium
What metabolic state could increased contractility in the heart? (1)
Hypercalcemia
!!! Pulmonary Artery values
15-25/8-15 mmHg
!!! Equation for MAP=
(sBP + (2 x dBP))/3
Normal Range of MAP
60-80 mmHg
CVP can evaluate the preload on what side of the heart?
On the RIght side
Pulmonary Artery Occlusion Pressure is able to measure the preload on what side of the heart?
On the Left side of the heart.
It’s between the R atrium and R ventricle but before the L atrium and L ventricle.
What part of the cardiopulmonary system would the after load in the R ventricle be related to?
It would be relative to the constriction/dilation of the pulmonary vessels, pulmonary artery capillaries and pulmonary vein.
Measured by calculating PVR in the right ventricle
