Lectures 3 & 4 Flashcards
(43 cards)
According to Dalton’s Law, what is the Partial Pressure of Oxygen and Nitrogen in ROOM AIR at Sea Level (760 mmHg)
Oxygen 21%- (0.21 x 760)= 160 mmHg
Nitrogen 78%- (0.78 x 760)= 600 mmHg
What is the Alveolar Gas Equation at sea level?
pAO2= FiO2 × (760-47) -(pACO2)/R
What is a “good” partial pressure of CO2 and where is this present?
- 40 mmHg
2. Alveolus and the Artery
What is the Partial Pressure of O2 (ppO2 or pO2) in Room Air, Trachea, Alveolus (pAO2), and the Artery (paO2)?
Room Air 160 mmHg
Trachea 150 mmHg
Alveolus 100 mmHg
Artery 95 mmHg
Where is the Partial Pressure of Water Vapor present at what value is it?
- In Trachea and the Alveolus
2. 47 mmHg
What is the Partial Pressure of Nitrogen (ppN or pN) in Room Air, Trachea, Alveolus (pAN), and the Artery (paN)?
Room Air 600 mmHg
Trachea 563 mmHg
Alveolus 523 mmHg
Artery 578 mmHg
What is the Alveolar-Arterial Gradient and what is a typical value for it?
- Difference between pAO2 (Alveolar) and (paO2) arterial
2. Typically between 5-10 mmHg
What could lead to an increase in the Alveolar-Arterial Gradient?
A Diffusion problem where not all of the blood from the right side of the heart is oxygenated
What is Anatomic Dead Space?
- Tissue that is not involved in gas exchange like the first 16 generations of the lung
- 150 mL
- Measured via Fowler’s Method (N2 concentration by O2 washout)
Under normal circumstances, what are the Ventilation Volumes, Flows, and Rates?
Ventilation= 7500 mL/min Frequency- 15 breathes/min Tidal Volume- 500 mL each breath Anatomic Dead Space- 150 mL each breath (2250 mL/min) Alveolar Ventilation- 5250 mL/min Pulmonary Blood Flow- 5L/min
What are the 4 Capacities measured via Spirometry?
- Functional Residual Capacity- All of the air beneath Tidal Volume (FRC= ERV+RV)
- Inspiratory Capacity (IC=TV+IRV)
- Vital Capacity- all you can move (VC= IRV+TV+ERV)
- Total Lung Capacity- everything (TLC= IRV+TV+ERV+TV)
What are the 4 Volumes measured via Spirometry?
- Tidal Volume- 500 mL moved each breath
- IRV (Inspiratory Reserve Volume)- 3000 mL moved with max inspiration not including Tidal Volume
- ERV (Expiratory Reserve Volume)- 1100 mL moved with max expiration not including Tidal Volume
- Residual Volume- 1200 mL always in the Lung to keep alveolar open
What is Vital Capacity and what is the equation for it?
- Maximum amount of air you can move going from with Max inspiration and expiration
- VC=IRV+TV+ERV
What is Forced Vital Capacity?
Same as Vital Capacity (maximum amount of air you can move going from with Max inspiration and expiration) BUT it is less than VC because you get less air out when it is forced
What volume of the lung CANNOT be measured by Simple Spirometry? What capacities CANNOT be calculated because of this?
- Residual Volume CANNOT be measured
2. Therefore Functional Residual Capacity and Total Lung Capacity CANNOT be calculated
What is Functional Residual Capacity?
- FRC= ERV+RV
2. Represents Volume of lung where tendency of the lung to spring out and the chest wall to recoil are balanced
What is Physiological Dead Space?
- Volume of gas that does NOT participate in gas exchange and does NOT eliminate CO2
- Measured via Bohr’s Method
How can you measure Anatomical Dead Space?
Fowler’s Method- Individual breathes in 100% O2 and N2 in exhaled air is measured. This basically measures the amount of N2 displaced by the inhaled O2.
How can you measure Physiological Dead Space?
Since Physiological Dead Space does not contribute CO2, use the Bohr Equation:
Physiological Dead Space Volume= TV x {(paCO2-peCO2)/paCO2}
peCO2 is expired CO2
SIDENOTE: pACO2=paCO2
How can you measure Communicating Gas (all of the parts of the lung that can be reached by the outside)?
Helium Dilution Method- have person breathe Helium from Spirometer for several breaths then measure how much Helium is left
What is Alveolar Ventilation?
VA= TV- (Dead Space x Rate)
What is the equation for the Volume of CO2 exhaled per unit time?
VCO2= Alveolar Ventilation x (%CO2/100) x K
What happens to CO2 if Ventilation is cut in half?
CO2 is DOUBLED if Ventilation is HALVED
What is Hypoxemia?
Abnormally low concentration of O2 in blood (low paO2)
