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21 Cards in this Set
- Front
- Back
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What is the tidal volume (definition and amount)?
What is the functional residual capacity? |
Air entering lung with each normal inspiration
about 500ml The volume of gas left in the lung after a normal expiration |
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What is the dead space (definition and amount)?
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The conducting airway which doesn't exchange gases
about 150 ml |
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Is there more alveolar gas or pulmonary capillary blood??
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ALVEOLAR GAS! 3000ml
Pulm cap blood is only 70ml |
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What is the maximum exhaled value called after taking a maximum inhalation?
What is the name of the gas that remains in the lung after this? |
Vital capacity
Residual volume |
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Which gas do you use in a spirometer to measure FRC or residual volume? Why this one?
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Helium - insoluble in blood
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Solving for FRC using Helium:
When helium is in equilibration C1 x V1 = C2 x (__ + __) |
V1 + V2
solve for V2 - this is the FRC |
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Measuring FRC using a plethysmograph relies on Boyle's law that ______ x ______ is constant
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pressure x volume
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The body plethysmograph measure the total colume of gas in the lung, including any trapped behind closed airways
Helium dilution measures only communicating gas. They are the same in young people, but not in who? |
In pts with lung disease the ventilated volume may be considerably less than the total volume because of gas trapped behind obstructed airways
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What is total ventilation?
What is alveolar ventilation |
Volume exhaled x Breathing rate
500ml x 15 breaths/min = 7500ml/min Only the amount that goes into the respiratory zone (subtract 150ml for the dead space) = 5250 ml/min |
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What is the equation for determining alveolar ventilation?
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VA = VE - VD
Alveolar ventilation = Expired total ventilation - Dead space |
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All expired CO2 comes from the _____ gas since there is no gas exchange in the anatomic ____ ____. Therefore:
VA = VCO2/PCO2 x K |
alveolar
dead space Alveolar ventilation = (Volume of CO2 exhaled/time)/Partial pressure of CO2 x constant |
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If the alveolar ventilation is halved and CO2 production remains unchanged, the alveolar and arterial PCO2 will do what?
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Double
VA = VCO2/PCO2 x K |
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Fowler's method of plotting expired volume against N2 concentration % is made to measure what?
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Anatomic dead space - the volume of the conducting airways
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Bohr's equation uses CO2 expiration from the alveolar gas. Partial pressure of a gas is proportional to its concentration. What is this measuring?
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Physiologic Dead Space - volume of gas that doesn't eliminate CO2
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In patients with lung disease, the ______ dead space may be considerably larger than ______ because of inequality of blod flow and ventilation within the lung
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physiologic (functional measurement)
anatomic (morphological measurement) |
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You can use _____ gas to measure regional differences in ventilation. ____ regions of the lung ventilate better than do the ____ zones and it changes with position based on gravity.
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Xenon (radioactive)
Lower Upper |
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The only variable in the following list that cannot measured with a simple spirometer and stopwatch is:
A. Tidal volume. B. Functional residual capacity. C. Vital capacity. D. Total ventilation. E. Respiratory frequency. |
B
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Concerning the pulmonary acinus:
A. Less than 90% oxygen uptake of the lung occurs in the acini. B. Percentage change in volume of the acini during inspiration is less than that of the whole lung. C. Volume of the acini is less than 90% of the total volume of the lung at FRC. D. Each acinus is supplied by a terminal bronchiole. E. The ventilation of the acini at the base of the upright human lung at FRC is less than those at the apex. |
D
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In a measurement of FRC by helium dilution, the original and final helium concentrations were 10% and 6%, and the spirometer volume was kept at 5 liters. What was the volume of the FRC in liters?
A. 2.5 B. 3.0 C. 3.3 D. 3.8 E. 5.0 |
C
Amount of He at start = amount of He at equilibration C1 = concentration of He at start, C2 = concentration of He at equilibration C1V1 = C2 (V1 + FRC) 10% x 5 L = 6% (5 L + FRC) |
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If CO2 production remains constant and alveolar ventilation is increased threefold, the alveolar PCO2 after a steady state is reached will be what percentage of its former value?
A. 25 B. 33 C. 50 D. 100 E. 300 |
B
PAco2 = Vco2/VA VA goes from 1 to 3 with the same amount of co2 produced |
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In a measurement of physiologic dead space using Bohr's method, the alveolar and mixed expired PCO2 were 40 and 30 mm Hg, respectively. What was the ratio of dead space to tidal volume?
A. 0.20 B. 0.25 C. 0.30 D. 0.35 E. 0.40 |
B
PACO2 = 40 mmHg PECO2 = 30 mmHg Bohr’s equation: VD/VT PAco2 - PEco2 / PAco2 40-30 / 40 = .25 |
