Term
| What is Expired Ventilation? |
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Definition
Amount of gas expired each minute.
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Term
| What is Respiratory Dead Space? |
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Definition
| This is any portion of lungs that receives adequate ventilation, but does not receive any blood flow (perfusion). |
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Term
| For each 500 ml of inspired air, how much does not take part in gas exchange? |
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Definition
150 ml. This is referred to as anatomic dead space.
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Term
| How much fresh air reaches the alveoli with each breath? |
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Definition
| 350 ml since 150 ml is ventilating only the conducting airways |
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Term
| What is the equation for alveolar volume? |
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Definition
VA = VT - VD
Alveolar Volume = Tidal Volume - Dead Space Volume |
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Term
| What is Alveolar Dead Space? |
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Definition
| This is any portion of alveoli that are no perfused, but ventilated and thus do not participate in gas exchange. |
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Term
| What is Physiologic Dead Space? |
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Definition
| This is the sum of Anatomic and Alveolar Dead Space. It consititues all parts of tidal volume that do not participate in gas exchange. |
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Term
| What is the effect of a large Physiologic Dead Space? |
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Definition
| Ventilation of a large dead space will increase the energy needed to maintain adequate oxygenation. The total work of breathing will increase. |
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Term
| What are some ways that perfusion is decreased in the lungs? |
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Definition
Pulmonary Emboli
Emphysema
Pulmonary Fibrosis
Adult Respiratory Distress Syndrome
Heart Failure, Hypotension and Hypo-Perfusion |
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Term
| Which equation is used to measure Dead Space? |
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Definition
| THe Bohr Equation measures the VD/VT ratio. In normal individuals, physiological dead space will equal anatomic dead space. In diseased individuals, physiological dead space will increase. |
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Term
| What is the normal VD/VT ratio? |
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Definition
| 0.2 - 0.35 during quiet breathing |
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Term
| T/F: Inspired gas contains a large amount of Carbon Dioxide. |
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Definition
| False. Inspired gas contains no Carbon Dioxide. All CO2 comes from aveolar gas. |
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Term
| What is the relationship between level of alveolar ventilation and PACO2? |
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Definition
| As alveolar ventilation increases, the level of PACO2 decreases. |
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Term
| What are some ways that carbon dioxide production will increase? |
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Definition
Exercise
Fever
Hypothyroidism
Tissue Repair
Infection
High Carbohydrate Diet |
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Term
| What is the way that ventilation accomodates for an increase in carbon dioxide production to maintain a PACO2 within the normal range? |
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Definition
| Ventilation will increase in order to accomodate. |
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Term
| What are two ways that alveolar ventilation can be decreased? |
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Definition
| Increased airway resistance and decreased lung compliance |
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Term
| What is hyperventilation and what is the key value that represents it? |
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Definition
| An increase in alveolar ventilation that exceeds the amount required by the rate of CO2 production. PaCO2 will be <35 mmHg |
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Term
| What is hypoventilation and what is the key value that represents it? |
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Definition
| Decrease in alveolar ventilation below the level required by the rate of CO2 production. PaCO2 > 45 mm Hg. |
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Term
| What are causes of hyperventilation? |
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Definition
Hypoxemia
Metabolic Acidosis
Anxiety
Pain
Hypotension
Fever or Sepsis |
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Term
| What are causes of hypoventilation? |
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Definition
Airway Obstruction
Restiction of chest wall or lung parenchyma
Respiratory depression by drugs, alcohol, or disease
Spinal Cord injury affecting respiratory centers |
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Term
| What is the alveolar air equation? |
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Definition
PAO2 = FIO2(PB - PH2O) - PACO2/R where R=0.8
= .21(760-47) - 40/0.8 |
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