Alveolar ventilation Flashcards
What are the four lung volumes?
RV
ERV
Vt
IRV
What is normal value for tidal volume?
500 mL
What is the normal value for inspiratory reserve volume?
3000-3300 mL
What is the normal value for expiratory reserve volume?
1000-1200 mL
What is the normal value for residual volume?
1200 mL
What are the four lung capacities?
IC
FRC
VC
TLC
What is the normal value for IC?
3500 mL
Vt + IRV
What is the normal value for FRC?
2400 mL
ERV + RV
What is the normal value for VC?
4700 mL
IRV + ERV + TV
TLC - RV
What is the normal value for TLC?
5900 mL
What are methods that can be used to measure FRC?
Helium dilution
Nitrogen wash out method
Body plethysmograph
Why can helium be used to measure FRC?
Very low solubility in blood
What are the major obstructive diseases?
Asthma
Emphysema
Chronic bronchitis
Bronchiectasis
Cystic fibrosis
Bronchiolitis
Tumor
What are the 2 conditions of restrictive diseases?
Interstitial lung diseases
Extrapulmonary disorders
What changes in the TLC, FEV1, FVC , and their ratio are seen in obstructive diseases?
FEV1 decreases
FVC decreased or normal
Ratio decreases
TLC increases or stays the same
What changes in TLC, FEV1, FVC, and their ratio are seen in restrictive lung diseases?
TLC decreases
FEV1 decreased or normal
FVC decreases
Ratio stays the same or increases
What is the equation for minute/total ventilation?
Vt x RR
What is the normal value for minute ventilation?
About 6 L/min
What is dead space ventilation?
Volume of air that never reaches the gas exchange areas
What is alveolar ventilation?
Rate at which new air reaches gas exchange areas
What is the equation for determining alveolar ventilation?
Minute ventilation - Vd = Va
What is the relationship between alveolar ventilation and pulmonary blood flow (CO)?
Approximately equal
What is a reasonable estimate of anatomic dead space?
1 mL per pound of ideal body weight
How can anatomic dead space be determined?
Fowler’s method
What is alveolar dead space?
Amount of alveoli that are ventilated by not perfused
How can physiologic dead space be measured using the Bohr method?
Vd/Vt = (PaCO2 - PeCO2)/PaCO2
What is Dalton’s law of partial pressure?
The partial pressure of a particular gas in a gas mixture is equal to its fractional concentration times the total pressure
What is the normal partial pressure of O2 at sea level?
~ 160 mmHg
What is the equation for Dalton’s law?
PlO2 = FlO2 (Pb - Ph2o)
Where Pb = atmospheric pressure
Where Ph2o = 47 mmHg
FiO2 = concentration of oxygen
What is Boyle’s law?
Gasses move from areas of high pressure to areas of low pressure
What is the alveolar gas equation?
PaO2 = PlO2 - PaCO2/R = FlO2 (Pb - Ph2o) - PaCO2/R
What is the alveolar ventilation equation?
PaCO2 = 0.863 x (Vco2/Va)
What are the effects of hypoventilation?
Increases alveolar and arterial PCO2
Decreases PO2
What are the effects of hyperventilation?
Alveolar PCO2 decreases
Alveolar PO2 increases
What is eupnea?
Normal quiet breathing
What is the distribution of ventilation at low lung volumes?
Pressure at base will exceed atm making ventilation impossible. Therefore the upper regions are better ventilated.
What is the effect of aging on lung volumes and capacities?
Decreased chest wall compliance
Increased lung compliance
Little change in TLC
Increased RV
Decreased FVC
Decreased FEV1
Decreased diffusion capacity
