Chapter 2 Flashcards
What can be measured using a simple spirometer?
- Tidal Volume
- Vital Capacity
What needs helium dilution or body plethysmography to measure?
- Total Lung Capacity
- Functional Residual Capacity
- Residual Volume
Why is Helium used in the helium dilution measurement?
- It has very low solubility in blood
What does the use of body plethysmograph depend on?
- Boyle’s Law
- PV = K at constant temp
What is total ventilation?
- Tidal Volume x Respiratory Frequency
What is Alveolar Ventilation?
- The amount of fresh gas getting to alveoli
- (Vt - Vd) x n
What is Physiologic Dead Space?
- Volume of gas that does not eliminate CO2
Compare the Anatomic and Physiologic Dead Space.
Healthy individual
- They are the same
Acute and Chronic Lung Disease
- Physiologic Dead Space is increased
What is the average tidal volume?
- 500ml
What is the average total ventilation?
- 7500ml/min
What is the average breathing frequency?
- 15/min
How do you calculate alveolar ventilation?
- (tidal volume - anatomical dead space) x frequency of breathing
How much can pulmonary capillary blood hold?
- 70ml
What is the average pulmonary blood flow?
- 5000ml/min
What is Total Lung Capacity?
- Total Volume the lungs can hold
What is Vital Capacity?
- Total Volume Inhaled after a full exhale
What is Tidal Volume?
- Average inhale/exhale amount (eupnea)
What is Functional Residual Capacity?
- Total Volume in lungs following tidal volume exhale
What is Residual Volume?
- Volume left in the lung following a full exhalation
How is Helium used to measure functional residual capacity?
V2 = V1(C1-C2)/C2
V2 = FRC
V1 = Volume 1
C = concentration
What is Boyle’s Law? how is it used in body plethysmography?
P1V1 = P2(V1 - change in V)
P1 = pressure in box prior to inspiratory effort
P2 = pressure in box after inspiratory effort
V1 = Pre-inspiratory box volume
Change in V = change in volume of box (or lung)
P3V2 = P4(V2 + change in V)
P3 = mouth pressure prior to inspiratory effort
P4 = Mouth pressure after inspiratory effort
V2 = Functional Residual Capacity
What is the equation for Alveolar Ventilation? What is the best way to increase it?
VT = VD + VA
VTxn = VDxn + VAxn
VA. = VE. - VD.
Best way to increase VA. is to increase Tidal Volume
Why are the lower regions of the lung better ventilated than the upper regions of the lung?
- Effects of gravity on the lung
