PFT Flashcards
(105 cards)
Two types of ventilatory region
Deadspace Ventilation and effective alveolar ventilation
It occurs in a ventilatory region where gas exchange perfusion is not available.
Deadspace ventialtion
where gas exchange perfusion is available
effective alveolar ventilation
The volume of the conducting airways from the mouth/nose down to and
including the level of the terminal bronchiole
Anatomic deadspace
The volume of malfunctioning alveoli that are lacking normal gas distribution
Alveolar deadspace
The total volume of deadspace in the pulmonary system; consists of the
the sum of the anatomic and physiologic deadspace combined; may also referred as “functional deadspace”
Physiologic deadspace
Alveolar units where the quantity of ventilation exceeds the quantity of perfusion available; result in a partial deadspace ventilation effect
ventilation in excess of perfusion
It measures the volume of a subject’s conducting airways. This provides a measure of the subject’s anatomic deadspace volume
Fowler method
What are the equipment required in Fowler test
rapid-response gas analyzer for nitrogen and spirometer system. Nitrogen washout for frc determination or single-breath nitrogen elimination test.
Test administration step 1
Inhale and breathe 100 % O2 through single-breath O2 inspiration
With inspiration, the subject’s alveoli contain a mixture of
N2 and the inspired
02
The presence of N2 results from the preexisting
residual volume gas
It differs, however, in that it allows room air instead of 100% 02-to be inhaled for the test. The tracing and calculations are based on FEC02 values measured during exhalation
Carbon dioxide meter in spirometer
Bohr Equation
deadspace over tidal volume is equal to the quantity of FACO2 - FECO2 over FACO2
The equipment needed to perform the bohr test includes
a spirometer for measuring exhaled volumes, a Douglas bag for collecting and exhaled gas sample, a CO2 analyzer, and an end-tidal PCO2 analyzing system or equipment for arterial blood sampling and analysis.
what is the duration of collection time of exhaled gas in Bohr tests
5-10 minutes
What is the normal values of Vd/Vt
.20 and .40
It is what states that alveolar deadspace begins to develop measurably and that Vd increases to become greater than the Vdan.
Pathologic states
What are the normal values for VAeff
31/min to 81/min
Relative increase in Vaeff can lead to
Hyperoxia and hypocapnia
Decreases in VAeff can cause
Hypoxemia and hypercapnia
If a rapid, shallow breathing pattern is adopted by the subject, there will be relatively
more deadspace ventilation and less effective alveolar ventilation
If a slower, deeper breathing pattern is adopted by the subject, there will be relatively
less deadspace ventilation and more effective alveolar ventilation
Increase anatomic deadspace is caused by
- Disorders that cause destruction or dilation of the airway walls (bronchiectasis) .
Breathing at a greater FRC level or with larger inspiratory volumes (air trapping/hyperinflation).
- Bronchodilator agents.