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26 Cards in this Set
- Front
- Back
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Two factors needed to have good breathing? |
Ventilation (V) Perfusion (Q) |
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Normal V/Q |
0.8 - 1 |
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V/Q = 0, what does this mean? Ex? |
Perfusion is normal No ventilation
*Ex. Atelectasis - small airway collapse, hypoventilation, absorption of O2 |
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Atelectasis |
One or more areas of lung collapsed or didn't inflate properly and lung coloured purplish |
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V/Q = infinity, what does this mean? Ex? |
Ventilation is normal No perfusion
*Ex. blood clot, profound hypotension |
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Partial pressures of O2 and CO2 in the alveoli, if:
1. V/Q = 0 2. V/Q = 1 3. V/Q = infinity |
1. O2 = 40mmHg, CO2 = 45mmHg 2. O2 = 100mmHg, CO2 = 40mmHg 3. O2 = 150mmHg, CO2 = 0mmHg |
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When V/Q is normal (ratio = 1) |
Balance between ventilation and perfusion such that optimal gas exchange is taking place *Equal volume of air and blood meeting in alveoli |
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What is it called when there is a deviation from normal?? |
V/Q mismatch or V/Q inequality |
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V/Q of zero is also known as ______, because.... |
"Shunt" blood is being shunted from right side (venous) circulation, to left side (arterial) circulation without any gas exchange occurring. |
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Adaptation that animals have to divert blood away from poorly ventilated areas of the lung? |
Hypoxic pulmonary vasoconstriction |
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Hypoxic pulmonary vasoconstriction |
Constriction in the arterioles that supply the hypoxic alveoli induced by alveolar hypoxia (PAO2 <70mmHg) |
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What is thought to mediate hypoxic pulmonary vasoconstriction? |
Nitric Oxide |
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What is the result of hypoxic pulmonary vasoconstriction? |
Shunt effect is minimized PaO2 is maximized |
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V/Q = Infinity is also known as... |
Dead Space Ventilation |
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Why Dead Space Ventilation? |
Volume of gas is being moved in and out of the body without any gas exchange occurring |
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What is Physiologic Dead Space? |
Air that doesn't undergo gas exchange |
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Dead Space Volume |
Anatomic PLUS Physiologic dead space |
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Are both extremes abnormal? |
Not really.. They are both occurring at different parts of the lung due to gravitational effects of body position |
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Dorsal area of lung and V/Q ratio |
>1 More ventilation than perfusion (air lighter than blood) |
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Ventral area of lung and V/Q ratio |
<1 More perfusion than ventilation (blood pools due to gravity) |
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Blood flow and pressures driving blood flow in Zone 1 (dorsal) |
Lowest PA > Pa > Pv |
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Blood flow and pressures driving blood flow in Zone 2 (middle) |
Medium Pa > PA > Pv |
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Blood flow and pressures driving blood flow in Zone 3 (ventral) |
Highest Pa > Pv > PA |
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How do we deal with V/Q issues? |
-Try to get lungs and chest wall functioning as a unit -Provide supplemental O2 to improve oxygenation -Support cardiovascular system with fluid/drugs -Ventilate patient if not breathing on own -Consider changing body position |
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How can we get lungs and chest wall functioning as a unit again? |
Drain air or fluid Fix diaphragmatic hernia.. etc |
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How can we support the cardiovascular system when dealing with V/Q issues? |
Increase blood pressure and cardiac output in order to push blood into under-perfused areas |
