Pulmonary Circulation and
Pulmonary Edema
DR KAMRAN AFZAL
OBJECTIVES
1. Describe regional differences in pulmonary
blood flow in an upright person
2.
Define zones I, II, and III in the lung, with
respect to pulmonary vascular pressure and
alveolar pressure
3. Describe the major functions of the bronchial
circulation
4. Discuss pulmonary edema
5. Identify Clinical Correlations
Distribution of blood circulation
1. 280 billion capillaries, supplying 300 million alveoli
2. Total volume of blood in all vessels
1. man: 5.4 l (70-80 ml / kg)
2. woman: 4.5 l (65-70 ml / kg)
3. Distribution:
1. Heart 7%
2. Pulmonary circulation 9-10%
3. Systemic circulation 84%
1.
2.
3.
4.
from that veins 75%
large arteries 15%
small arteries 3%
capilaries: 7%
DOUBLE CIRCULATION
Double circulation is made
possible because of heart
advantage
1. all body organs with
oxygenated blood at high
pressure
2. at low pressure to the lungs
as they are spongy tissue
Pulmonary Blood Pressures
Gravity and Distance:
– Distance above or below the heart (arterial ,venous)
– Distance between Apex and Base
Pulmonary Capillary dynamics
1. Starling forces (ultra filtration)
1.
2.
3.
4.
Capillary hydrostatic P = 7 mmHg.
Interstitial hydrostatic P = -8 mmHg.
Plasma colloid osmotic P = 28 mmHg.
Interstitial colloid osmotic P = 14 mm
2. Filtration forces = 15 mmHg.
3. Reabsorption forces = 14 mmHg.
4. Net forces favoring filtration = 1 mmHg.
5. Excess fluid removed by lymphatics
3 Zones
.
1. 23 mm Hg pressure difference between top and bottom
2. At top, 15 mm Hg < than the PAP at the level of the heart
3. At the bottom, 8 mm Hg greater than the PAP at the level
of the heart.
Gravity and Blood Flow
Regional Pulmonary Blood Flow Depends Upon
Position Relative to the Heart
Main PA
Apex
Base
15 mmHg
2 mmHg
25 mmHg
Gravity, Alveolar Pressure, and Blood Flow
1. Typically no
zone 1 in normal
healthy person
zone 2 (intermittent flow) at the
apices.
zone 3 (continuous flow) in all
the lower areas.
2. Large zone 1 in positive
pressure ventilation
3. In normal lungs, Zone 2
begins 10 cm above the
mid-level of the heart to the
top of the lungs.
Effect of hydrostatic P on regional pulmonary flow
From apex to base capillary P  (gravity)
1. Zone 1:
2. no flow
3. alveolar air pressure (PALV) is
higher than arterial pressure durin
any part of cardiac cycle.
4. Zone 2:
5. intermittent flow
6. systolic arterial pressure higher th
alveolar air pressure, but diastolic
arterial pressure below alveolar ai
pressure.
7. Zone 3:
8. continuous flow
9. pulmonary arterial pressure (Ppc)
remain higher than alveolar air
pressure at all times.
Lung Ventilation/Perfusion Ratios
1. The ratio of V/Q in lung at rest 0.8 (4.2 L/min ventilation
divided by 5.5 L/min blood flow).
2. When the ventilation (Va) is zero, yet there is still
perfusion (Q) of the alveolus, the Va/Q is zero.
3. at the other extreme, when there is adequate ventilation,
but zero perfusion, the ratio Va/Q is infinity.
4. At a ratio of either zero or infinity, there is no exchange of
gases through the respiratory membrane of the affected
alveoli
Lung blood flow rises towards bases and
also during Exercise
1.- at rest, the blood flow is very low
at the top of the lungs; most of the
flow is through the bottom of the
lung.
2.-During exercise, flow ↑(4-7) fold.
- Top of lung ↑ by 700 to 800%,
the - =bottom by 200 to 300%.
reason for these differences is PAP
↑ during exercise to convert the lung
apices from a zone 2 to a zone 3
pattern .
Double circulation
in the respiratory system
1. Bronchial Circulation 2. Pulmonary Circulation
1.
Bronchial 1. Arises from L Ventricle.(systemic - oxygenated).
2. 1-2% of left ventricular output.
3. Supplies the supporting tissues of the lungs, including
the connective tissue, septa, and bronchi.
• Venous return from the bronchial by 2 routes.
1. bronchial drainage is into azygous (1/2)
2. 2.pulmonary veins (1/2) (short circuit
• Pulmonary Circulation
•
•
Right Ventricle.
Receives 100% of blood flow.
Arises from
Special features of bronchial circulation
1. LV output > (1=2%) than RV output & some deO2 blood into
O2ated pulmonary venous blood + L atria
2. Does not supply beyond terminal respiratory units (respiratory
bronchioles, alveolar ducts, and alveoli)
3. Bronchial arterial pressure is =same as Aortic pressure, and
bronchial vascular resistance is > than resistance in the
pulmonary circulation
4.Only capable of undergoing angiogenesis,(new vessels).
Definition:
• Pulmonary edema is a condition
characterized by fluid accumulation in the
lungs caused by back pressure in the lung
veins. This results from malfunctioning of
the heart.
Causes:
• Pulmonary edema is a complication of a
myocardial infarction (heart attack), mitral
or aortic valve disease, cardiomyopathy, or
other disorders characterized by cardiac
dysfunction.
Pathophysiology:
• Fluid backs up into the veins of the lungs.
Increased pressure in these veins forces
fluid out of the vein and into the air spaces
(alveoli). This interferes with the exchange
of oxygen and carbon dioxide in the
alveoli.
Symptoms:
• Extreme shortness of breath, severe
difficult breathing
• Feeling of "air hunger" or "drowning"
• "Grunting" sounds with breathing
• Inability to lie down
• Rales
• Wheezing
• Anxiety
Symptoms:
•
•
•
•
•
•
•
Restlessness
Cough
Excessive sweating
Pale skin
Nasal flaring
Coughing up blood
Breathing, absent temporarily
Signs:
• Listening to the chest with a stethoscope
(auscultation) may show crackles in the
lungs or abnormal heart sounds.
• A chest x-ray may show fluid in the lung
space.
• An echocardiogram may be performed in
addition to (or instead of) a chest x-ray.
Tests:
Blood oxygen levels (low)
A chest X-ray may reveal the following:
Fluid in or around the lung space
Enlarged heart
Tests:
An ultrasound of the heart
(echocardiogram) may reveal the
following:
Weak heart muscle
Leaking or narrow heart valves
Fluid surrounding the heart
Treatment:
• This is a medical emergency! Do not delay
treatment. Hospitalization and immediate
treatment are required.
• Oxygen is given, by a mask or through
endotracheal tube using mechanical
ventilation.
Expectations (Prognosis):
• Pulmonary edema is a life-threatening
condition. It is often curable with urgent
treatment and subsequent control of the
underlying disorder.
Complications:
• Long-term dependence on a breathing
machine (ventilator)