Hemodynamic Parameters Flashcards
RAP (Right arterial Pressure/CVP (Central Venous Pressure)
Explain CVP and RAP
1-8 mmHG
CVP is the pressure of blood in the thoracic vena cava, near the right atrium. CVP reflects the amount of blood returning to the heart. CVP is a good approximation of RAP.
PAP (Pulmonary Arterial Pressure)
15-26 mmHg systolic
5-15 mmHg diastolic
8-12 mmHg mean
Explain the PAP
Normal pulmonary artery systolic pressure: 15-26 mmHg.
Systolic pressure reading of a P.A. catheter represents right ventricular ejection of blood into the pulmonary arteries.
Normal pulmonary diastolic pressure: 5-15 mm Hg.
Diastolic pressure reading of a P.A. catheter represents the run-off of blood from the pulmonary arteries to the pulmonary veins and left ventricle.
PCWP (Pulmonary Capillary Wedge Pressure)
4-12 mmHg
Explain the PCWP
Pulmonary capillary wedge pressure reflects the amount of blood filling the left ventricle.
SVR (Systemic Vascular Resistance)
800-1200 dynes/sec/cm-5
Explain SVR
SVR is the measure of afterload for the left ventricle.
SVR is determined by the radius of the arterioles, viscosity of the blood, and the length of the vessels
What causes in increase in SVR
Hypertension, Hypothermia, vasoconstriction of arterial bed
PVR (Pulmonary Vascular Resistance)
20-120 dynes/sec/cm-5
Explain PVR
Rresistance that the right ventricle must overcome to eject blood into the pulmonary arteries.
An increase in PVR leads to?
With increased PVR patients can develop right sided heart failure known as Cor Pulmonale.
EF (Ejection Fraction)
Explain
60-70%
The percentage of blood the left ventricle pumps out with each contraction (stroke)
SV (Stroke Volume)
Explain
70-80ml
Stroke volume is the amount of blood ejected by the left ventricle in one contraction
SV is influenced by
preload, afterload, and contractility
CO (cardiac output)
How do you calculate CO?
Explain CO
4-8 L/min
HR x SV
Cardiac output is the volume of blood pumped by the heart per minute (mL blood/min)
CI (Cardiac Index)
How to calculate CI?
Explain CI
2.5-4 L/m2
CO/BSA
Cardiac Index is a more accurate measurement of cardiac output because it takes into account the patient’s body surface area (BSA)
Explain Preload
Stretching of the ventricle when blood enters the ventricle at end diastole. The more the heart muscle stretches the forceful the contraction will be during systole
How do you measure preload
RAP/CVP for right ventricle
PCWP for left ventricle
Explain Contractility
Refers to the ability of the ventricle to stretch to contract.
The greater the stretch the greater the contractility.
What influence contractility and how?
Influenced by Preload and afterload
If preload is too hight or too low contractility can be decreased.
If afterload is too high, contractility can be decreased because heart muscle may not be able to overcome the high resistance.
Explain Afterload
Refers to the pressure the ventricle must generate to overcome the higher pressure in the aorta (pulmonary artery) to get the blood out of the heart (or right ventricle in the PA).
How is afterload measured?
SVR in the left ventricle.
PVR for the right ventricle.
Explain Compliance
Compliance of the ventricle is the ability to stretch.
If compliance decreases (ventricle is stiff) the pressure of the ventricle will decrease d/t less blood entering the ventricle.
Normal MAP
How to calculate the MAP
70-110 mmHg
MAP= Systolic + (2)Diastolic/ 3
Explain the MAP
MAP is the average pressure in the arterial system during systole and diastole. It tells us how well all organs are perfused
