Respiratory Disease Flashcards
A normal breath volume is AKA?
Tidal volume
The remaining gas in the lung after normal expiration is AKA
Functional residual capacity
What is the maximum expiratory volume after a maximum inspiration?
Vital capacity
What is the remaining gas n the lung after MAX expiration?
Residual volume
By Ficks law of diffusion, diffusion rate is proportional to??
Tissue area
Partial pressure difference
Solubility of gas in tissue
By Ficks law of diffusion, diffusion rate is inversely proportional to??
Tissue thickness and square root of molecular weight
T/F: CO2 diffuses mor rapidly than O2
True 20x faster
- higher solubility
- similar molecular weight
What is the definition of hypoxemia?
PaO2 <60mmHg
SpO2 90%
What are the 5 causes of hypoxemia?
Hypoventialion Anatomic R to L shunt Low inspired O2 Diffusion impairment Ventilation-perfusion mismatch
How is hypoventilation defined?
High PaCO2 >40mmHg
Will result in hypoxemia if breathing room air (FiO2 0.21)
Not at 100% oxygen (FiO2 1)
At 100% oxygen, PaO2 should be??
500mmHg
What is an anatomic R->L shunt?
Blood entering arterial system without going through ventilated area of lung (eg PDA)
T/F: there are some normal small R->L anatomic shunts
True
- bronchial artery
- coronary enough blood (thesbeian veins)
Under what conditions can you have a low inspired FiO2?
High altitude
Anesthesia —> delivery of hypoxic gas mixture (rare)
What are examples of diffusion impairment ? How common is this in vet species?
Thickened blood-gas barrier
Rare in vet sp.
What is V/Q mismatch? What are causes?
V= ventilation Q= perfusion
When these are not equal can lead to hypoxia
V/Q = 0 —> perfusion occurs without ventilation (eg atelectasis )
V/Q = infinity —> ventilation without perfusion (eg pulmonary thromboembolism)
What is hypoxic pulmonary vasoconstriction (HPV)?
Normal physiological mechanism to match V:Q
Alveolar hypoxia —> vasoconstriction of small pulmonary arteries
How do anesthetic drugs affect hypoxic pulmonary vasoconstriction??
Decreased reflex
—> increased V:Q mismatch
—> decrease PaO2:FiO2