Which patient is ventilating more effectively?
A: RR 30, Vt 200ml
B: RR 10, Vt 600ml
Note both have a MV of 6L
Must answer with math explanation!
patient B ventilates more effectively. Due to better alveolar ventilation (the volume of inspired gas that actually takes part in gas exchange)
Alveolar ventilation patient B=4500ml
Alveolar ventilation patient A= 1500ml.
Vasoconstriction of the smooth muscle in the walls of the small arterioles of the lung occurs in response to hypoxia where? What is this phenomenon called?
Vasoconstriction occurs when Po2 of alveolar gas decreases (not PaO2!!). Happens in vitro as well.
Note nonlinear nature of curve. Sharp increase in vasoconstriction below PAO2 of 70mmHg
What is the definition of the P50 in adults?
Bonus: What is the actual number?
Super Amazeballs bonus: p50 of fetal hbg=?
Super Amazeballs bonus: p50 of sickle hgb=?
The oxygen tension (partial pressure of oxygen or paO2) at which hgb is 50% saturated
26.6mmHg
fetal=19 mmHg
sickle=31mmHg
Ficks law states: The rate of transfer of a gas through a sheet of tissue is proportional to the tissue area and the difference in gas partial pressure between the 2 sides and inversely proportional to this?
Tissue thickness
What is the equation for the Law of Poiseuille. What does this law govern as it relates to pulmonary physiology?
Describes the pressure-flow characteristics for laminar flow through a tube (in this case air flow through lungs)
What are the 2 components of physiologic dead space? What % of Vt is normally dead space (or roughly how many mL?)
The lung volume at which dependent airways begin to close is called?
Bonus: how does this change with age?
Super Amazeballs Bonus: Why does this change with age occur??
Closing capacity
Deoxygenated (or reduced) hgb has a higer affinity for CO2 than oxygenated hgb. Phrased another way: the lower the saturation of hgb with O2, the larger the concentration of CO2 for a given PCO2. This phenomonon is called.....?
The Haldane Effect
Pay attention to the much more linear nature of the CO2 dissociation curve vs. the oxy/hgb dissociation curve.
The lung volume at any given pressure during deflation is larger than that same pressure during inflation. This is called?
SuperAmazeballsBonus: explain the picture
Hysteresis. Lung compliance is non-linear, lungs are much less compliant at higher lung volumes.
SAB: a saline filled lung has a much higher compliance than an air filled lung because saline in the alveoli abolishes the surface tension.
.21(247-47) = 42mmHg
Use your knowledge of the law of Poiseuille to explain the following hyperinflated CXR of a severe COPD patient
The lung expansion pulls open the conducting airways thus increasing radius thus improving airflow
Where is the lung most compliant?
Base
Name 3 other functions of the lung besides gas exchange.
will also accept surfactant production
Explain this picture using words like dead space and shunt
Bonus: the normal V/Q ratio of a healthy alveolus/capillary unit is 0.8. Why?
Super Amazeballs bonus: Where is the V/Q ratio the highest? lung apex or base? Must explain :)
bonus: because normal alveolar ventilation is 4L/m while normal pulmonary capillary perfusion is 5L/m (aka CO).
SAB: apex. As you go from bottom to top of lung ventilation perfusion decreases faster than ventilation (due to gravity)
12.5 ml/dL
Where is max ventilation in the lung?
Where is max perfusion in the lung?
SuperAmazeballsBonus: explain using TPP
Base
There are 4 important lung capacities. What are they. What are they comprised of? Maybe you should just draw it :)
The central chemoreceptors on the ventral surface of the medulla govern an increase in ventilation if a patient is hypoventilating. How does this occur???
How do the following clinical situations change dead space? (increase or decrease)
.
In a measurement of physiologic dead space using Bohr's method the alveolar and mixed expired pCO2 were 40 and 30 mmHg respectively. What is the ratio of dead space to Vt?
0.25
Draw and explain west's zones of the lung
Explain:
.
Name 3 things that shift the oxy/hgb dissociation cure Left. 3 things that shift it right
Explain how during childbirth fetal circulation transitions to adult circulation.
HPV!