Term
| Where is the lowest partial pressure of oxygen found in the body? |
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Definition
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Term
| Ventilation vs. Perfusion? |
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Definition
Ventilation = When oxygen is brought into contact with the alveoli.
Perfusion = when blood is brought to the pulmonary capillaries, and gases passively move across the alveolar capillary membrane down a concentration gradient by diffusion |
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Term
| What is the respiratory quotient (R)? |
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Definition
On a normal diet, more oxygen is used by cells than carbon dioxide is produced by the cells.
The ratio, R, = CO2 production/O2 consumption
Normally averages around 0.8, but varies with diet |
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Term
| How is alveolar partial pressure measured? |
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Definition
PAO2 = PIO2 - PaCO2/R
Note: if the subject breath 100% pure oxygen, the equation can be simplified to:
PAO2 = PIO2 - PaCO2 |
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Term
| What is the normal for PaO2? |
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Definition
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Term
| What is the A-a gradient? |
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Definition
| The difference between the calculated PAO2 and the measured PaO2 |
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Term
| What is the normal for PaCO2? |
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Definition
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Term
| What are two causes of increased PaCO2? |
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Definition
1. When an increase in CO2 production is not associated with a compensatory increase in alveolar ventilation
2. When total alveolar ventilation is decreased |
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Term
| What two factors determine the amount of oxygen delivered to tissues? |
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Definition
1. the arterial oxygen content, which factors in hemoglobin level, PaO2, arterial saturation, and
2. the cardiac output |
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Term
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Definition
The amount of gas inhaled and exhaled each minute
= Tidal volume x the frequency of breathing (breaths/min)
Note: the volume of gas exhaled is slightly lower than the volume of gas inhaled due to the respiratory quotient |
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Term
| What is tidal volume and what is the normal? |
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Definition
| The amt of gas inspired each breath and is normally around 500 mL per breath |
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Term
| What is the dead space volume? What is the normal? |
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Definition
| It is the portion of each tidal volume that never reaches the alveoli and is normally around 150 mL |
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Term
| What is hypoventilation and hyperventilation? |
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Definition
Hypo - PaCO2 above 45 mmHg
Hyper - PaCO2 below 35 mmHg |
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Term
| What is Forced Expiratory Volume 1 Second (FEV1) and how can it be used clinically? |
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Definition
It is the volume of Vital Capacity that can be expired forcefully in one second
Measured by maximal inspiration to Total Lung Capacity, and then exhaling as forcefully and comletely to Reserve Volume. The total forced air is the Forced Vital Capacity. FEV1 is one second of that.
It is useful in the diagnosis and Tx of asthma, chronic bronchitis, and emphysema. |
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