Topic 4 Flashcards
How can you measure CO?
ultrasound or catheterizations
Why is Catheterizations the preferred method to measure CO?
provide both pressures and flows within the heart and vessels
How can you indirectly measure SV?
ultrasound echocardiography
What is an advantage and problem with Stroke work?
used to assess metabolic demand but hard to measure
what are the four phases of the cardiac cycle?
ventricular filling, isovolumetric contraction, ejection and isovolumetric relaxation
what is the difference of the cardiac cycle for the RV and pulmonary artery?
lower pressures
what is CO?
amount of blood pumped out on each beat (SV) x heart rate (HR)
What is the normal resting values of CO (changes based on size)?
4-8 liter/min
when can CO dramatically increase?
exercise
CO =
SV x HR
SV =
EDV - ESV
ejection fraction =
SV / EDV
MAP =
DBP + PP/3
systemic vascular resistance =
(MAP - CVP)/CO
what influences CO?
heart’s work
What is afterload and how can it help determine cardiac work?
chamber volume needed to eject blood against aortic pressure
what is stroke work?
work performed during one beat
how do you calculate stroke work?
area of PV loop
rather than stroke work, what is a better way to compare work between individuals?
stroke work index = SW/body surface area
stroke work is hard to measure so we use –
cardiac index = CO/body surface area
What is EDV?
volume before contraction
What is ESV?
minimal vol of ventricle after the max is squeezed out
