Term
| Where is the site of gas exchange? |
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Definition
| Alveolar Capillary Membrane |
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Term
| What is the most common mechanism producing hypoxemia in respiratory diseases? |
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Definition
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Term
| What is the Aveolar Space? |
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Definition
| Areas where gas exchange between alvelous and pulmonary capillary takes place |
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Term
| What is alveolar hypoxia? |
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Definition
| When blood extracts a greater amount of O2 from the alveolus than can be replaced by inefficient ventilation |
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Term
| T/F: Carbon Dioxide levels are inversely proportional to the level of alveolar ventilation. |
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Definition
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Term
What is the V/Q ratio in:
1. Normal Perfusion
2. Hypoventilation
3. Hyperventilation
4. Physiological Dead Space
5. True Shunt |
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Definition
1. 1
2. <1
3. >1
4. ∞
5. 0 |
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Term
| What happens to the PaO2 of venous blood that passes through an alveolus that is hypoventilated? |
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Definition
| The PaO2 will be lower than normal with a corresponding higher PaCO2. |
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Term
Two Compartment Model
1. What happens to the compartment opposite that of the hypoventilated alveolus?
2. What about the systemic arterial PO2? |
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Definition
1. The corresponding V/Q will go up since total ventilation remains the same. This is, in effect, to make up for the lower ventilated alveolus.
2. That will depend on the actual ratios and PAO2s of the compartments that are involved. |
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Term
Two Compartment Model
What is the net effect of the hemoglobin saturation with one alveolus hypoventilated the the other normal? |
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Definition
| The total hemoglobin will decrease since the slight increase in the adapted normal alveolus will only make up a small amount for that lost in the hypoventilated alveolus. This is because of the sigmoid shape of the HB curve. |
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Term
Two Compartment Model
What is the effect on the CO2? |
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Definition
| Because the CO2 curve is more linear, there is less of an effect due to the hypoventilated alveolus. |
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Term
| What is an alveolar unit? |
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Definition
1. The alveolus
2. The conducting airways connecting the alveolus to the environment |
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Term
| What can cause a regional decrease in ventilation? |
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Definition
1. Decrease in compliance
2. Increase in resistance in the conducting airways |
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Term
| What are some factors that decrease alveolar compliance? |
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Definition
Pulmonary Edema
Alveolar Fluid
Pulmonary Fibrosis
Ateleactasis - collapse of alveoli |
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Term
| What are some factors that increase airway resistance? |
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Definition
Bronchospasm
Airway Secretions
Peribronchial Edema
Tumor
Foreign Body in Airway Lumen
Upper Airway Obstruction |
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Term
| With increased dead space (V/Q = ∞), maintaining alveolar ventilation at normal levels requires an increase in what? |
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Definition
| Minute Ventilation. This increases the amount of work required from ventilation. |
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Term
| What is the concern when a patient has a significant increase in minute ventilation? |
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Definition
| Patient may be compensating for increased physiologic dead space caused by various factors. |
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Term
| What are some general causes of regional decreases in perfusion? |
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Definition
1. Embolization
2. Fibrosis
3. Destruction of Vascular Bed (Emphysema) |
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Term
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Definition
| Disease state that causes destruction of lung tissue: alveoli, connective tissue around alveoli, and pulmonary arterioles, capillaries, and venuoles |
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