Ventilation - Trachte Flashcards
What does ventilation refer to?
The amount of air entering and leaving the lungs per minute.
Describes how gas (oxygen) gets to the alveoli.
What is alveolar ventilation?
The amount of air exchanging with blood.
What are the different lung volumes?
- Total lung capacity
- Vital capacity
- Tidal volume
- Residual volume
- Functional residual capacity
What is the total lung capacity?
- Vital capacity + residual volume
- usually about 6,000 mL depending on size of person & altitude
Can the total lung capacity be measured directly?
NO
Measured indirectly by dilution of a nonexchangeable gas (He) or with a body plethysmograph.
What is the Vital Capacity?
- The maximum volume of air that can be exhaled after a maximum inspiration
- usually about 6,000 mL
- depends on size & altitude
- decreases with age
- usually about 6,000 mL
Can the Vital Capacity be measured directly?
Yes
(measured with spirometer)
What is the Residual Volume?
- The amount of air remaining in the lungs after a maximal expiration.
- usually about 1,500 mL
Can the Residual Volume be measured directly?
NO
Measured indirectly by dilution of a nonexchangeable gas (He) or with a body plethysmograph.
What is the Functional Residual Capacity?
- The amount of air remaining after a typical exhalation
- the natural resting state when the lungs and chest wall are not expanded (at rest)
- usually about 2,500 mL
- the natural resting state when the lungs and chest wall are not expanded (at rest)
Can the functional residual capacity be measured directly?
NO
Measured indirectly with a gas dilution technique using a nonexchangeable gas (He) or with a body plethysmograph.
What is the Tidal Volume?
- The amount of air normally inhaled & exhaled per breath
- usually 500 mL per breath
- 500 mL x 15 breaths/min = 7,500mL/min
- usually 500 mL per breath
Can the Tidal Volume be measured directly?
Yes
What is the relationship between CO2 concentration in alveolar gas and ventilation?
- [CO2] in alveolar gas is INVERSELY related to ventilation
- Alveolar ventilation = VCO2/PCO2 x K
- amount of CO2 in the exhaled air divided by the fractional concentration of CO2 in the expired air
- Alveolar ventilation = VCO2/PCO2 x K
What is anatomic dead space?
- Conducting airways
- The amount of a breath not reaching alveoli.