Chapter 2: Ventilation Flashcards
Which lung capacities and volumes cannot be measured by simple spirometry? Why?
Residual volume
Functional Residual Capacity (FRC)
Total Lung Capacity (TLC)
Residual Volume cannot be measured directly. FRC and TLC include RV, so also cannot be measured directly.
How do you calculate total ventilation?
Tidal volume x respiratory rate
What is the normal tidal volume?
500 mL
What is the Vital Capacity (VC)?
Volume of air expired from maximal inspiration to maximal expiration
How is the FRC defined?
Volume of air in lungs after normal (resting) expiration
What is the Expiratory Reserve?
Volume of air in lungs that can still be exhaled after a normal (resting) expiration?
What is the Inspiratory Reserve?
Volume of air that can still be inhaled after a normal (resting) inhalation?
What is the anatomical unit distal to a terminal bronchiole?
Acinus
Define acinus?
The portion of lung distal to a terminal bronchiole that forms an anatomical unit
Oxygen uptake occurs in which part of the lung?
Acini (respiratory bronchioles, alveolar ducts, alveoli)
At FRC, what percentage of lung volume is distributed in the acini?
About 95? (3 liters vs 150 mL)
In the upright lung, where is ventilation greatest?
Lower portion
For a patient sitting in a plethysmograph who makes an expiratory effort against a closed epiglottis, what happens to the following four quantities: airway pressure, lung volume, box pressure, and box volume
Airway pressure increases
Lung volume decreases
Box pressure decreases
Box volume increases
What is the Bohr relationship?
Assuming that no CO2 originates in anatomical dead space, the Bohr relationship describes the ratio of tidal to dead space volume as a function of alveolar and expired CO2. Has the form:
Vd/Vt = (PACO2 - PECO2)/PACO2
Vd = Dead space volume Vt = Tidal volume PACO2 = Alveolar CO2 PECO2 = Mixed expired CO2
