Pulmonary circulation€¦ · Pulmonary circulation Physiological anatomy: the Pul Artery is 5cm...
Transcript of Pulmonary circulation€¦ · Pulmonary circulation Physiological anatomy: the Pul Artery is 5cm...
Pulmonary circulation Physiological anatomy: the Pul Artery is 5cm length and thin (1/3 of aorta ) , while
the branches are short and have more diameter so it will have a large compliance (7 ml/mmHg).
pulmonary veins are thin & short. bronchial arteries originate from the systemic circulation
(carry 1-2% of C.O -oxygenated blood-) then empty into pulmonary veins then to the left atrium so the left ventricle pumps 1-2% more than the right ventricle.
rich lymphatic drainage to the right thoracic duct to
prevent edema
Pressures in the pulmonary system:
1- Right ventricle: 25-1 mmHg
2- Pulm. Artery: 25-8 mmHg
3- Pulm. cap. : 8 mmHg
4- Left atrium & major veins: 2 mmHg
5- Pulmonary wedge pressure about 5mm hg.
Increase in congestive heart failure
Blood volume of the lungs: :
450 ml ( 9% of total blood volume)
70 ml are found in the capillaries
Blood volume of the lungs -Lungs as blood reservoir
if the person is bleeding or blowing air out hardly the volume can reach 200 ml.
if the person has left heart failure or mitral valve stenosis or regurgitation the volume can reach 900 ml shift from systemic
Circulation.
MEASUREMENT OF PULMONARY
BLOOD FLOW
Fick Principle
VO2 = Oxygen Consumption CaO2 = Arterial Content
CvO2 = Venous Content
VO2=Q(CaO2-CvO2
)
Q = Blood flow
MEASUREMENT OF PULMONARY BLOOD
FLOW
VO2 = 250 ml/min
CaO2 = 20 ml O2/100 ml blood
CvO2 = 15 ml O2/100 ml blood
VO2=Q(CaO2-CvO2
)
Q = 250 ml O2/min = 250 ml O2 * 100 ml blood
(20-15) ml O2/100 ml blood min 5 ml O2
Q = 5000 ml blood /min
Blood flow
Effect of alveolar [O2]:
when [O2] decreases below 70% of normal alveolar epithelial cells secrete vasoconstrictors adjacent blood vessels constrict blood flows to better aerated alveoli (extreme low [O2] 5x resistance)
Effect of hydrostatic pressure:
in normal upright adult there’s a difference between the lowest and highest points of the lung
the gradient is 23 mmHg (15 mmHg above the heart & 8 mmHg below it)
Regional pulmonary blood flow : 1-Zone 1: No blood flow (capill. pr. < alveol, pr.) 2-Zone 2: Intermittent blood flow 3-Zone 3: Continuous blood flow. (capill. pr. > alveol. pr.) in normal lungs zone 1 cannot be found, zone 2 is in the
apex of the lung and zone 3 represents the base.
Regional pulmonary blood flow :
arterial pressure in pulmonary artery is 25-8 mmHg at apex systolic 25-15= 10 mmHg
during diastole 8-15 mmHg= -7?
(Hydrostatic pressure difference is 15 mmHg between the level of the heart and the lung apex)
if the person is lying down or exercising only zone 3 can be seen.
C. Increase flow to the top by about 700-800% and
200-300% in the lower part because during exercise convert apices from zone 2 to zone 3
PULMONARY CIRCULATION IN LEFT SIDE HEART FAILURE
When the left atrial pressure increase more than 7mmhg will cause increase of pulmonary arterial pressure which will increase the load on right ventricle.
Pulmonary capillary dynamics: 7 mmHg cap. Pressure. blood passes through the capillary in 0.8sec increasing the C.O lowers the time to 0.3sec Capillary fluid exchange dynamics: outward forces= 7+14+8 = 29 mmHg inward forces = 28 mmHg mean filtration pr. = 1 mmHg “handled by lymph”
lungs Systemic cir.
Capillary pressure 7 mmHg 17 mmHg
Interst. Osm. Pr. 14 mmHg 8 mmHg
Interst. Neg. pr. -8 mmHg -3 mmHg
Pulmonary Capillary Dynamics Outward Forces
Pulmonary capillary pressure 7 mmHg
Interstitial osmotic pressure 14 mmHg
Negative interstitial pressure 8 mmHg
Total 29 mmHg
Inward Forces
Plasma osmotic pressure 28 mmHg
Net filtration pressure 1 mmHg
Negative interstitial pressure keeps alveoli dry
Pulmonary Capillary Dynamics
Hydrostatic
Osmotic
+7 -8
28 14
+1
Lymphatic pump
0
-8 surface tension
Net
hydrostatic pressure
-5
Pulmonary edema Alveoli are always dry except for a small amount of fluid
secreted by alveolar cells on the alveolar surface. When interstitial pressure becomes (+) water will fill the alveoli Causes: 1- Left-sided heart failure ↑ venous+cap. pr 2-Damage to the pulmonary capillary membrane caused by : a- infections (pneumonia) b- breathing chlorine gas or sulfur dioxide gas.
Safety factors 21 mmHg in acute states
35 mmHg in chronic cases ( Lymph expand)
Left Atrial Pressure
Edem
a F
orm
atio
n
Heart Failure and Pulmonary Edema
25 0
Pulmonary Edema
Causes of pulmonary edema
left heart failure
damage to pulmonary blood cap membrane, as
In pneumonia or breathing chlorine gas or sulfur dioxide gas
Safety factor
negative interstitial pressure
lymphatic pumping
decreased interstitial osmotic pressure
PLEURAL EFFUSION Pleural effusion (edema) : Collection of large free fluid
in the pleural space
1-Blockage of lymphatic drainage from pleural space
2- Cardiac failure (increase peripheral and pulmonary cap pressure)
3- Decrease plasma colloid osmotic pressure
4- Infection or inflammation of the surface of pleural
cavity