Term
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Definition
| The process by which fresh gas enters the lungs during inspiration and is brought to the alveoli |
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Term
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Definition
| The process by which mixed venous blood is brought to the alveoli |
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Term
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Definition
The amount of air inspired with each normal breath
Vt |
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Term
| What is minute ventilation? |
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Definition
The amount of air inspired each minute
Tidal volume per breath times the number of breaths per minute
Vm = Vt x f |
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Term
| What is expired ventilation? |
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Definition
The amount of gas exhaled each minute
Ve
Vm is slightly greater than Ve because the ratio of carbon dioxide production to oxygen consumption is usually less than 1. This ratio is the respiratory quotient (R) and is usually 0.8 |
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Term
| What is larger, minute ventilation or expired ventilation? |
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Definition
| Minute ventilation; the ratio of carbon dioxide production to oxygen consumption (R) is usually less than 1 |
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Term
| For each 500 ml of air inhaled, how much remains in the conducting airways and does not take part in gas exchange? |
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Definition
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Term
| Alveolar volume is equal to what? |
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Definition
| Tidal volume - dead space volume |
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Term
| What is physiologic dead space? |
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Definition
| It is the sum of the anatomic dead space and the alveolar dead space; constitutes all parts of the tidal volume that do not take part in gas exchange |
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Term
| What diseases can result in increased physiologic dead space? |
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Definition
| Pulmonary emboli, emphysema, pulmonary fibrosis, adult respiratory distress syndrome, and heart failure |
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Term
| Does a mechanical ventilator increase or decrease dead space? |
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Definition
| Increases; the volume of gas within the endotracheal tube constitutes dead space |
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Term
| What is the purpose of the Bohr Equation? |
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Definition
| To measure physiological dead space |
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Term
| True or False: Anatomical dead space always equals physiological dead space |
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Definition
| False; in disease, physiological dead space can greatly exceed anatomical dead space |
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Term
| What is the relationship between alveolar ventilation and alveolar carbon dioxide? |
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Definition
| As alveolar ventilation increases, alveolar carbon dioxide decrease, and vise versa |
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Term
| What is hyperventilation? |
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Definition
An increase in alveolar ventilation greater than that required by the rate of CO2 production; the diagnosis of hyperventilation requires that the PaCO2 be less than 35 mm Hg (normal range is 35-45)
Causes include hypoxemia, metabolic acidosis, anxiety, pain, hypotension, and fever or sepsis |
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Term
| What are causes of hypoventilation? |
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Definition
| Airway obstruction, restriction of the chest wall or lung parenchyma, respiratory depression by drugs, alcohol, or neurological disease, neuromuscular disease producing weakness of the respiratory muscles, and spinal cord injury resulting in paralysis of the respiratory muscles |
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Term
| What is alveolar ventilation? |
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Definition
The amount of fresh gas entering the respiratory zone each minute
Vam = Va x f |
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