Hemodynamic Concepts Flashcards
1
Q
Hemodynamic Equation
A
- Cardiac Output = Heart Rate x Stroke Volume
- CO = HR x SV
- SV: Made up of Preload, Contractility, and Afterload
2
Q
Stroke Volume
A
- SV determined by preload, afterload, and contractility
- Normal SV = 50 to 100 mL per beat
- Preload
- CVP (right ventricular)
- PAOP (left ventricular)
- Contractility
- Afterload
- PVR (right ventricular)
- SVR (left ventricular)
- As stroke volume increases, CO increases
- SV is how many mL per beat the left ventricle ejects
3
Q
Cardiac Output
A
- Normal CO is 4 L to 8 L per minute
- If CO is critically low, blood pressure will decrease
4
Q
Cardiac Index
A
- Cardiac index (CI)
- Takes into account the body surface area (BSA)
- More meaningful value than CO
- Normal CI = 2.5 to 4.0 L/min/m2
5
Q
Heart Rate (HR)
A
- As HR increases, CO increases
- Extreme bradycardia results in low CO and hypotension
- Increase in HR first sign of compensation for a low CO (occurs before BP drops)
- Extreme tachycardia also decrease CO
- Loss of diastolic filling time occurs
- Ventricles do not have time to fill, ventricular preload drops, and ventricles cannout put out what is not delivered
6
Q
Preload
A
- Volume/pressure in the ventricle at the end of diastole after the AV valves close, just prior to ejection
- Right atrial (RA) pressure or central venous pressure (CVP) reflects the right ventricular preload
- PAOP reflects the left ventricular preload
- As preload increases, SV and CO increase up to a point
- Too high of preload may lead to heart failure
- Preload will seldom be elevated if the heart is without disease and there are no metabolic abnormalities
7
Q
Afterload
A
- Pressure (resistance) against which the ventricle must pump to open the valve (pulmonic or aortic)
- Clinically measured by the pulmonary vascular resistance (PVR) for the right ventricle or systemic vascular resistance (SVR) for the left ventricle
- As afterload increases, SV and Co decrease
8
Q
Contractility
A
- The contractile force of the myofibrils independent of preload and afterload
- As contractility increases, SV and Co increase
9
Q
Normal Hemodynamic and Oxygen Parameters
A
10
Q
Hemodynamic Profiles for Select Abnormal Conditions
A
11
Q
Hemodynamic Effects of Various Cardiovascular Agents
A
12
Q
Therapies for Alterations in Hemodynamics
A
13
Q
Hemodynamic Oxygenation Parameters
A
14
Q
SvO2 Changes
A
15
Q
Acute Mitral Valve Insufficiency
A