Lectures 3 & 4 Flashcards Preview

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Flashcards in Lectures 3 & 4 Deck (43):

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?

1. 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?

1. 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?

1. 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?

1. Tissue that is not involved in gas exchange like the first 16 generations of the lung
2. 150 mL
3. 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?

1. Functional Residual Capacity- All of the air beneath Tidal Volume (FRC= ERV+RV)
2. Inspiratory Capacity (IC=TV+IRV)
3. Vital Capacity- all you can move (VC= IRV+TV+ERV)
4. Total Lung Capacity- everything (TLC= IRV+TV+ERV+TV)


What are the 4 Volumes measured via Spirometry?

1. Tidal Volume- 500 mL moved each breath
2. IRV (Inspiratory Reserve Volume)- 3000 mL moved with max inspiration not including Tidal Volume
3. ERV (Expiratory Reserve Volume)- 1100 mL moved with max expiration not including Tidal Volume
4. Residual Volume- 1200 mL always in the Lung to keep alveolar open


What is Vital Capacity and what is the equation for it?

1. Maximum amount of air you can move going from with Max inspiration and expiration


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?

1. Residual Volume CANNOT be measured
2. Therefore Functional Residual Capacity and Total Lung Capacity CANNOT be calculated


What is Functional Residual Capacity?

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?

1. Volume of gas that does NOT participate in gas exchange and does NOT eliminate CO2
2. 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


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)


What is Hypercarbia?

Abnormally high concentration of CO2 in blood (high paCO2)


At high altitude what comes first, Hypoxemia or Hypercarbia?

Hypoxemia (Abnormally low concentration of O2 in blood)


With Interstitial Lung Disease what comes first, Hypoxemia or Hypercarbia?

Hypoxemia (Abnormally low concentration of O2 in blood) because this would mean the interstitium is fibrotic


During Hypoventilation what comes first, Hypoxemia or Hypercarbia?

Hypercarbia (Abnormally high concentration of CO2 in blood)


What can be measured by Carbon Monoxide?

Diffusion since CO immediately binds to Hemoglobin and doesn't change concentration in the blood


What is the difference between Hypoxia and Hypoxemia?

1. Hypoxemia is low oxygen in the blood (low paO2)
2. Hypoxia is low oxygen in the tissue


What are some causes of Hypoxemia?

1. Hypoventilation (low inspired O2)
2. Interstitial Disease
3. Ventilation-Perfusion Inequality
4. Shunt


How can you calculate Alveolar O2?

Alveolar O2= Ambient O2- Inspired O2
(0.21 x Air Pressure) - [0.21 x (Air Pressure - 47)]
Answer should be around 90-100


How can you increase low inspired O2 (low paO2)?

By increasing the proportion of O2 in the gas mixture from 21% to a larger fraction


What does Hypoventilation do to pACO2 and paCO2 concentrations?

Hypoventilation ALWAYS INCREASES pACO2 and paCO2


How can we overcome Diffusion Limitation?

By increasing the change in Pressure so O2 will diffuse more rapidly into the blood. This can be done by adding oxygen


What is a V/Q mismatch and what does it cause?

V= Ventilation or Airflow
Q= Perfusion or Blood flow
Normally V/Q=1, but:
1. While choking V=0 so V/Q is decreasing to 0
2. Bloodclot means Q=0 so V/Q is increasing to infinity


What is Total Deadspace?

Sum of Anatomic Deadspace (parts where gas exchange does NOT occur) + Physiological Deadspace (Alveolar space that is well ventilated but perfusion is blocked by pulmonary embolus)


What is an Anatomic Shunt?

It is a type of Physiological Shunt where blood enters the arterial system without ever going through ventilated areas of the lungs


What is Anatomic Deadspace?

Space that may have ventilation but has NO perfusion so gas exchange does NOT occur


What is the only case of Hypoxemia that CANNOT be resolved by administering Oxygen?

Anatomic Shunt


Where is Perfusion (Blood Flow) greatest in the lung and why?

At the BOTTOM because Alveoli are small so blood vessels are all fat allowing blood to flow easily


Where is Ventilation (Air Flow) greatest in the lung and why?

At the BOTTOM because they change size more easily at the bottom


What happens to the slope of a V/Q graph as you move from the bottom of the lung to the top?

It goes up (sort of like a J) and is greatest at the top because Perfusion (Q) decreases much faster than Ventilation (V)