Pulmonary Vascular Physiology Flashcards
There are 2 types of circulation
Pulmonary circulation and Bronchial circulation
Pulmonary circulation
From Right Ventricle
Receives 100% of cardiac output (4.5-8L/min)
Red cell transit time ≈5 seconds.
280 billion capillaries & 300 million alveoli.
Surface area for gas exchange 50 – 100 m2
Bronchial circulation
2% of Left Ventricular Output
Vessel wall of pulmonary arteries is thin
Vessel wall of systemic arteries is thick
Muscularization of pulmonary arteries is minor
Muscularization of systemic arteries is major
There is no Need for redistribution in pulmonary artery in normal state
There is Need for redistribution in systemic arteries
What is the pressure in the RA? (MmHg)
5
What is the pressure in the RV? (MmHg)
25/0
What is the pressure in the PA? (MmHg)
25/8
What is the pressure in the LA? (MmHg)
5
What is the pressure in the LV? (MmHg)
120/0
What is the pressure in the aorta? (MmHg)
120/80
Left ventricle is larger than hothead right ventricle as
The left ventricle sees higher pressure than the right ventricle
Pouiseuille’s Law
Resistance= (8 x L x viscosity) / (pi x r^4)
Effect of Transmural Pressure on Pulmonary Vessels During Inspiration
Ohms law
V= IR
Pressure across circuit =
Cardiac output x Resistance
Pressure across pulmonary circulation=
mPAP – Left Atrial Pressure x Pulmonary Vascular Resistance
Pressure across pulmonary circulation
mPAP – PAWP = CO x PVR
mPAP (mean pulmonary arterial pressure),
PAWP (pulmonary arterial wedge pressure left atrial pressure),
CO (cardiac output), PVR (pulmonary vascular resistance)
What happens to mPAP on exercise?
On exercise mPAP remains stable in normal subjects but CO increases significantly
How is this possible?
Recruitment and Distention in Response to Increased Pulmonary Artery Pressure
Two types of respiratory failure
Type I
Type II
Type 1 Respiratory Failure
pO2 < 8 kPA
pCO2 <6 kPA
Type II respiratory failure
pO2 < 8 kPA
pCO2 >6 kPA