Ventilation, Perfusion, Shunt Flashcards
Blood Flow
Perfusion (Q)
Air Flow
Ventilation (V)
At rest, your perfusion (Q) will be ______ in the reserve capillaries.
Slower
At rest, what type of blood flow is present throughout the lungs?
Gradient Blood Flow
At rest, the reserve capillaries will be toward the _____ of the lung
Apex
At rest, the recruited capillaries will be toward the ____ of the lung
Base
At rest, your perfusion (Q) will be ______ in the recruited capillaries of the lung.
Fast
At rest, in an individual capillary you have slow transit of blood in ______ capillaries and fast/rapid transit of blood in the _____ capillaries.
Reserve; Recruited
In other words, at rest, the blood flow in one minute will be lower in _______ capillaries than ______ capillaries.
Reserve; Recruited
During exercise, what type of blood flow is present throughout the lungs?
Even Blood Distribution; apex and base of the lung are the same.
In other words, during exercise, the blood flow in one minute will be _______ in reserved capillaries and recruited capillaries.
THE SAME
** Higher blood flow overall than at rest **
At rest, the mean arterial pressure will be ________.
Pretty low
V and Q are going to be greater at which part of the lung during rest?
Base of the lung
At rest, some of the alveoli at the BASE of the lung will be _______.
Collapsed
At rest, some of the alveoli at the APEX of the lung will be _______.
Inflated
At rest, V or Q is more evenly distributed?
V - Ventilation
At rest, why is perfusion (Q) more distributed at the base of the lung?
Below the heart and due to gravity.
At rest, a high obstruction of the heart can cause a decreased _____V or Q______.This can lead to what condition?
V (Ventilation). Could lead to Pulmonary Arterial Hypertension (>125 mm Hg)
** Common cause of obstruction in the lung is bronchitis **
During exercise, you are using all capillaries (Fully recruited capillaries). Why?
Because of the high/rapid perfusion that needs to get all over the lungs.
During exercise, your mean arterial pressure is roughly ______ mmHg.
30
At rest, your mean arterial pressure is roughly ____ mm Hg.
15
Lung zones locally modulare Q and V by what two actions?
- Gravity
2. Regional Metabolic Status
When the V/Q ratio is 0, what does this mean?
There is no VENTILATION! Does not matter if there is any perfusion!
Where in the body would you yield a V/Q of 0?
Mixed Venous Blood in the heart
Mixed Venous Blood usually has a PO2 of?
45 mm Hg
Mixed Venous Blood usually has a PCO2 of?
40 mm Hg
When the V/Q ratio is infinity, what does this mean?
There is no VENTILATION!
Where in the body would you yield a V/Q of infinity?
Inspired Air
Inspired Air usually has a PO2 of?
150 mm Hg
Inspired Air usually has a PCO2 of?
0 mm Hg
At the apex of the lung, at rest, the V/Q Ratio will be expected to be ______. Why?
HIGH!
Because there is a relatively high rate of ventilation RELATIVE to the perfusion. Remember perfusion rates are higher (with more recruited capillaries) at the BASE of the lung.
At the base of the lung, at rest, the V/Q Ratio will be expected to be ______. Why?
LOW!
Because there is a relatively low rate of ventilation RELATIVE to the perfusion. Remember perfusion rates are higher (with more recruited capillaries) at the BASE of the lung.
The _______ is the average blood flow between the apex and the base
Arterial Blood Flow
Arterial blood flow typically has a PCO2 of?
40 mm Hg
Arterial blood flow typically has a PO2 of?
100 mm Hg
What are the two main sources of V/Q mismatches?
- Shunt (due to obstruction)
2. Alveolar Dead Space (embolism or vasoconstriction of blood flow to alveolus.
When there is a shunt, what is the value of PO2?
40 mm Hg
normally 100 mm Hg
When there is a shunt, what is the value of PCO2?
45 mm Hg
slightly higher than normal [40 mm Hg] because of gas being trapped by obstruction
The V/Q ratio in a Shunt will be close to?
0
What is happening to V and Q in a shunt?
No inspired air is coming in (V=0), and the gas entering and leaving the alveoli remains the same as it was in the mixed venous blood.
What causes a shunt?
Obstruction
What causes Alveolar Dead Space?
Embolism or Vasoconstriction of blood flow to the alveolus
When there is an alveolar dead space, what is the value of PO2?
150 mm Hg
When there is an alveolar dead space, what is the value of PCO2?
0 mm Hg
Is there going to be perfusion with dead alveolar space?
NO! Q = 0
What is happening in Alveolar Dead Space
Inspired Air enters the alveoli, but there is no perfusion occuring.
The V/Q ratio of the Alveolar Dead Space
Infinity
In the Ventilation/Perfusion Test, what do they do to check ventilation? What is normally seen?
Radioactive Compound is inhaled into the airspace of the lung. If normal, it will distribute evenly to all regions.
In the Ventilation/Perfusion Test, what do they do to check perfusion? What would dictate an issue?
Radioactive Compound is injected into a vein that then travels into the lung and tissues in the blood vessels.
A clot/embolus would be preset if we see the injected material stopping somewhere.
What is a Pulmonary Embolus
Blood clot in the Pulmonary Artery
When comparing the two different parts of the test, if you see the inhaled compound but no perfusion, what is this?
Alveolar Dead Space
When comparing the two different parts of the test, if you see the injected compound but no ventilation, what is this?
Shunt
In an area of alveolar dead space, what would happen to the perfusion at OTHER locations in the lung?
Increased perfusion at other areas.
When there is a decreased blood flow, what happens in the alveoli?
Alveolar Type II Pneumocytes (Surfactant Producers) produce less, which causes a decreased compliance and ventilation.
In other words, the alveoli shrink.
What can cause bronchial constriction?
Increased PO2
Decreased PCO2
Increased pH
In a shunt, the ventilation in other parts of the lung will _____.
Increase
Hypoxia will be similar to a _____ due to the loss of O2.
Shunt
What compensatory response will occur in the alveoli with hypoxia?
Arterioles feeding the alveoli will constrict
Giving oxygen to a patient with a bad shunt will cause % saturation of O2 in the arterial blood to increase/decrease/stay the same.
Stay the same, there is no benefit in giving a patient with a bad shunt O2.
