Hemodynamics (Measurements/Values/Preload/Afterload) Flashcards
Describe the phlebostatic axis.
This is the bisection of the fourth intercostal space and the midaxillary line.
What is CVP or RAP? What does it tell us? range? What about the pressure in the vena cava?
central venous pressure (right atrial pressure) is the pressure of blood in the right atrium
RVEDP
0-8 mmHg
The pressure is very similar in the vena cava because there is no valve separating the VC and the RA.
What is PAWP used to determine in the heart? What is the range?
It is used to determine LVEDP.
8-12 mmHg
What is PVR? What does it effect and its range?
Pulmonary vascular resistance
It effects the afterload of the right ventricle
50-250
What is SVR, what does it effect, and what is its normal range?
Systemic vascular resistance
Afterload of the LV
800-1500
What is the normal number for cardiac output? What is it?
4-8L/min
The amount of blood pumped by the heart per minute
What is cardiac index? What is the normal range? What does it determine?
This is the CO indexed to the patients BSA.
2.5-4L/min
If the CO is meeting the bodies perfusion needs.
What is the normal stroke volume?
60-100ml/beat
What is the SvO2? What is its normal range?
Missed venous oxygen saturation - oxygen saturation of venous blood measured in the pulmonary artery
60-80%
What is RVSWI? What is its normal range?
Right ventricular stroke work index - The amount of work performed by the right ventricle with each beat
7.9-9.7
What is LVSWI? What is the normal range?
Work performed by the left ventricle with each beat
50-62
What is the normal range for systolic and diastolic pulmonary artery pressures? Does the systolic pressure range for the right ventricle differ from the systolic pressure range of the pulmonary artery?
Why is pressure in the pulmonary artery higher during diastole than the RVEDP?
20-30 systolic
8-15 diastolic
NO NO NO
The pressure must be higher in the artery during diastole in order to keep the valve closed.
How does increased intrathoracic pressure decrease preload?
ventricles become compressed and are unable to fill adequately
If the ventricles become compressed with the increase in intrathrocacic pressure, what can this do to pressures in the right atrium and ultimately CVP?
What are some things that can cause an increase in intratoracic pressure, which ultimately decrease preload?
This will increase the pressure in the right atrium despite the decrease in preload in the ventricles (atria have to work harder to get blood volume into the compressed ventricles, this can cause an increase in CVP.
PEEP, cardiac tamonade, tension pneumo
Other than increase intrathoracic pressure, what else can cause a decrease in preload?
volume loss - hemorrhage, diurese, vomiting
venous dilation - hyperthermia, vasodilators, endotoxins released in septic shock, neurogenic shock
3rd spacing
arrhythmias - effects atrial/ventricular filling synchrony or filling time (tachycardias)
