Perfusion Flashcards
diffs that make pulm. circulations different from systemic
- low pressure and volume
- low resistance
- pulsatile
- constrict with hypoxia
difference in resistance versus flow
pulm is 1/10 the resistance, so doesn’t need much pressure to push blood through
what is the name for the initial pressure required to open the arteries
critical opening pressure
is resistance in lungs linear?
no - changes at different flow rates
what changes in pulm. system with to help with increased flow during excercise
no pressure increase – therefore lower resisitance
how is resistance reduced?
- more vessels (parallel cicuit)
2. distension
3 forces affecting the pulm blood
- vessel caliber
- alveolar vessels
- extra-alveolar vessels - exposed to pleural pressure
how to assess left atrial pressure
Swan Ganz catheter
what does Swan Ganz catheter with tip inflated and deflated
- deflated - PA pressure
2. inflated - LA pressure
what happens in RV pressure due to embolism
if new will raise pressure to 45, if had for a while, will go higher due to time for RV hypertrophy
what does thermal dilution measure
cardiac output by looking at degree that cold is diffused out
formula to measure cardiac output
VO2/(CaO2-CvO2)
where in the lungs is bloodflow greatest
bases
***3 things that affect blood flow to lungs
- Pa - driving pressure
- Pv - back pressure
- PA - alveolar pressure transmurally
pressure ratios in 3 heart zones
- PA>Pa>PV
- Pa>PA>PV
- Pa>PV>PA
3 effects of gravity on lung
- decr Pa above heart and incr. Pa below
- incr. Pv above heart and dec. PV below
- lesser effect on alveoli
what happens if have hypoxia
low diffusion so body compensates by lowering perfusion
what happens in block off R lung
hypoxemia>vasoconstriction>pulmonary hypertension
what is pulm. edema
blood vessels leaking fluid into lung
causes of pulm edema 2
- high pressure
2. leaky vessels - permiability or low protein solutes
