Test 3: Wk11: 10 Pulmonary Circulation and Edema - Dasgupta Flashcards
There are two circulatory systems associated with the lung.
Bronchial circulation
Pulmonary circulation
bronchial circulation is
part of the
systemic circulation.
bronchial circulation comprises of % of the cardiac output from the —
comprises of 2% of the cardiac output from the left heart
bronchial arteries supply the
tracheobronchial tree
About two-thirds of the bronchial capillary venous blood from Bronchial circulation drains into the
pulmonary veins
Bronchial circulation Shunt
two-thirds of the bronchial
capillary venous blood from this circulation drains into the pulmonary veins
Pulmonary circulation is driven by
right ventricle
The whole cardiac output is
delivered to the pulmonary circulation via the
lung
Vessel walls of the pulmonary vasculature are — and contain — smooth muscle than
corresponding segments in the systemic circulation.
much thinner
less
Since cardiac output of the left and right heart are essentially the same, pulmonary blood flow is equal to
the total
blood flow of the systemic circulation
blood flow measured to determine total cardiac
output
pulmonary blood flow
Pulmonary Arteries carry
deoxygenated blood
Pulmonary veins carry
oxygenated blood
Pulmonary capillaries have — walls and — vascular resistance
very thin
low
The pulmonary vessels offer — resistance to blood flow than do the systemic arterial vessels.
much less
pulmonary vessels are also much more — and — than systemic arterial vessels
distensible
compressible
Anastomoses connections between
between bronchial and
pulmonary capillary
Anastomoses function
They have little function in healthy adults but may open in pathological
conditions, such as when either bronchial or pulmonary blood flow to a portion of lung is occluded.
Pulmonary Circulation Systolic mean pulmonary Arterial pressure
Mean Diastolic
25 mmHg
8 mmHg
Pressure drop across systemic circulation
across pulmonary circulation
98mmHg
10mmHg
due to gravity both intravascular pressures and blood flow are considerably — at the apex than at the base of the lung
less
Pa top of lung
3cmH2O
Pa Middle of Lung
19cmH20
Pa bottom of lung
35cmH2O
resistance to blood flow —as you go to the bottom of the lung
decreases
perfusion is — in the top and — in the lowest part of the lung.
smallest
greatest
Zone 1 is defined as the region that is
not perfused
PA>Pa>Pv
Zone 2 is the region that is
perfused intermittently only at systolic pressure
Pa>PA>Pv
Zone 3 is the region in which
always perfused
Pa>Pv>PA
pt on ventilator has high amounts of
zone 1
Another name for Alveolar Hypoxia is
Hypoxia-induced vasocontriction
Alveolar Hypoxia
pulmonary vascular smooth muscle contracts in areas of low PO2
In people with
obstructive or restrictive diseases lung disease, the alveolar PO2 is low. So if the
overall PO2 is low, it causes
pulmonary vasoconstriction throughout the lung.
Vasocontraction throughout the lung can lead to
right heart failure
Recruitment
Opening of previously closed (collapsed) arteries.
Distension:
Increase in the radius of the existing blood vessels to allow blood flow. By
Poiseuille’s equation, this causes fall of PVR.
As lung volume increases during a normal negative-pressure inspiration, the alveoli
increase in volume
While the alveoli expand, the vessels found between them, mainly pulmonary capillaries are
are elongated
At high lung volumes, then, the resistance to blood flow offered by the alveolar
vessels
increases greatly
as lung volumes increase, the resistance to blood flow offered by the extraalveolar vessels
decreases
at high lung volumes (attained by normal negative-pressure breathing), the
resistance to blood flow offered by the extra-alveolar vessels
decreases
During mechanical positive-pressure ventilation, alveolar pressure (PA) and intrapleural
pressure are — during inspiration
positive
both the alveolar and extra-alveolar vessels are — as lung volume increases, and the resistance to blood flow offered by both alveolar and extra-alveolar vessels
— during lung inflation.
compressed
increases
PVR is elevated in both alveolar and extra-alveolar vessels
throughout the
respiratory cycle.
Because intrapleural pressure is always positive, a large number of blood
vessels throughout the lung are compressed and provide a high amount of resistance. This greatly
increases the workload of the right ventricle to pump blood to the heart.
High PVR and a fall in cardiac output may
cause right heart failure
Starling law
see slide 21
2 major types of pulmonary edema
- Hydrostatic Edema/ Cardiogenic Edema
2. Permeability Edema
Hydrostatic Edema/ Cardiogenic Edema caused by
increases in capillary pressure
no change in capillary filtration or reflection coefficient
Usually with Right Heart Failure
Hydrostatic edema is principally related to an increase
in capillary pressure
This type of edema is common with left heart failure due to left
ventricular infarction or mitral stenosis
Hydrostatic Edema
Permeability Edema
increase in permeability of vessel wall that separates blood from tissue
Permeability Edema increased — and decreased –
capillary filtration kf
reflection coefficient sigma
Permeability Edema also called
non-cardiogenic edema
principal disorder in ARDS
Permeability Edema
severe form of lung injury marked by persistent inflammation and increased capillary permeability
ARDS
ARDS sx
breathlessness, rapid shallow breathing, dry cough, chest pain
ARDS x-ray shows
diffuse airspaces and bilateral alveolar infiltrates
