APEX Respiratory Physiology Flashcards
Where does dead space end?
Terminal bronchioles
Next is respiratory bronchioles, which is where gas exchange begins
Muscles of expiration
“I let the air out of my TIRE”
internal intercostals
Rectus abdominis
external oblique/ internal oblique
Traverse abdominis
Muscles of inspiration
Diaphragm
External intercostals
Sternocleidomastoid
Scalene muscles
Primary determinant of CO2 elimination
Alveolar ventilation- more important than MV (Ve) bc it includes dead space
Alveolar ventilation formula
Vt-Vd x rr
What increases PaCO2/ETCO2 gradient?
Things that increase deadspace
PPV
Hypotension- decreased BP decreases ETCO2
Atropine- bronchodilator
Normal Vd?
33%
Define physiologic Vd
anatomical Vd + alveolar Vd
Anatomical vs alveolar Vd
Body part is confined to conducting airways
alveoli has ventilation but no perfusion
Things that change dead space
I- old age, copd, hotn, atropine, decreased co
D- ETT, LMA, Trach
The base of the lung has more / less what in compared to the apex in the sitting position
More blood, more CO2,
Less PO2, Less Vq ratio
The most compliant part of the lung
Base
V/Q= infiniti cause
Dead space
Does HPV minimize shunt or dead space?
Shunt!
Theres no shunting since theres no blood flow
It could be said that it increases Vd bc the air has to travel further for VQ
VQ=0 means
Shunt
The tendency of an alveolus to want to collapse is indirectly proportional to ____
Surface tension
The tendency of an alveoli collapse is directly inversely proportional to ______
Radius
VQ ratio in Zone 1, does zone 1 always occur? how does lung combat this zone?
infinity / 0
Zero blood flow
Does not occur in normal lung
To combat, bronchioles constrict
Zone 2 VQ ratio
1/1=1
Zone 3 VQ ratio
0 / infinity
Although, zone 3 is good, most zone 3 is just “shunt-like” bc the Q is higher than V
Anatomical shunts
Thesbian veins (drain L heart)
Bronchiolar veins (drain bronchial blood)
Pleural veins (drain bronchial blood)
Zone 4 lung
Too much fluid, not enough removal by lymph
Fluid overload, pulmonary edema, Mitral stenosis,
Hypoxemia define
PaO2 <80mmHg
Things that increase Aa gradient
VQ mismatch (too much V, COPD, embolism)
Older age
Shunt (Pneomonia, atelectasis, alveoli cant touch blood!)
Diffusion impairment- Same as shunt! (Emphysema, ILD, Fibrosis)