Pulmonary Phys Pearls Flashcards
What is lung dead space?
Can be anatomic (conducting paths take up lung space roughly 140L) or physiologic (disease states) however it is the portion of the lung that does not participate in O2 exchange.
What is vital capacity?
the sum of tidal volume, inspiratory reserve volume and expiratory reserve volume.
Essentially is the volume of air that can be forcibly expired after full inspiration.
Which three lung measurements cannot be measured by spirometry?
Functional residual capacitance (Residual volume + expiratory reserve volume)
and
Residual volume
and
Total lung volume (all four volume ammounts)
What is FEV1 and what is normal?
This is the ammount of lung volume that can be forcibly exhaled in one second.
Normally its 80% of the forced vital capacity.
Describe how FEV1 and FVC are affected by obstructive lung disease.
with asthma or COPD Both are decreased however, FEV1 is reduced more than the FVC and so FEV1/FVC is decreased.
Describe how FEV1 and FVC are affected by restrictive lung disese.
With restrictive diseases such as fibrosis, both are reduced however FEV1 is reduced less than FVC and so FEV1/FVC is increased.
What equation describes compliance of the respiratory and vascular system?
Compliance is = Volume / Pressure
This ultimately describes the distensability of the chest wall. It is inversely related to elastance which is the elasticity of the chest wall (how well it snaps back)
What feature of the lungs cause the inhalation and exhalation curves to appear different?
Hysteresis.
In other words, the lungs need to overcome surface tension when being inflated and thus the curve is sigmoid in shape compared to the exponential exhale curve.
Why is intraplearal space generally negative?
The chest wall naturally wants to expand where as the lungs naturally want to collapse.
Thus the two forces interact and create a relatively negative pressure.
A barrel shaped chest should make you think of?
Emphysema where the FRC (functional residual capacity) is increased leading to distended lungs and chest.
THIS IS OBSTRUCTIVE
How will the lungs react with fibrosis?
this is a restrictive condition. It is difficult TO GET AIR INTO THE LUNGS and thus the lungs will tend to collapse.
“Pink puffer”
Describe the relationship between alveolar radius and surface tension.
As radius increases the alveoli needs less pressure to remain open. Thus less likely to collapse.
P= 2T/r
surfactant helps make up the size diffrence.
What cell types make surfactact?
Type II alveolar cells.
What test can determine if an infant is making enough surfactant?
A lecthicin:sphingomyelin ratio of 2:1
What is the biggest factor effecting airway resistance?
Radius
By passouilles law 8Nl/pir^4
