19. Pulmonary Circulation Flashcards
What is pulmonary capillary wedge pressure used as a measure of
Left atrial pressure
What happens to lung blood volume in blood loss?
Decreases by up to 50%
blood shifts to systemic circulation
What happens to lung blood volume in left ventricular failure?
Doubles
Pulmonary congestion
What does low alveolar O2 cause?
Local vasoconstriction
blood is directed elsewhere
What does widespread hypoxic vasoconstriction cause?
Increased pulmonary resistance, work load on right ventricle and pulmonary artery pressure
What is the pressure at the apex of the lung?
-14mmHg
What is the pressure at the base of the lung?
8mmHg
What happens in zone 1?
No flow (at apex)
Capillary systolic pressure is less than alveolar
Only happens in abnormal conditions (eg. blood loss)
What happens in zone 2?
Intermittent flow
Capillary diastolic pressure is less than alveolar
Apex
What happens in zone 3?
Continuous flow
Capillary diastolic pressure is more than alveolar
Most of lung
What is pulmonary capillary pressure?
6 mmHg
What is the interstitial fluid pressure in pulmonary capillaries?
-8mmHg
What is the interstitial fluid colloid osmotic pressure in pulmonary capillaries?
15mmHg
What is the plasma protein colloid osmotic pressure?
28mmHg
What is the net filtration of pulmonary capillaries?
Outwards forces more than inward forces so small continuous flow into interstitial space
