Small Group 2 Gas Diffusion Flashcards Preview

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Flashcards in Small Group 2 Gas Diffusion Deck (7):

How do you calculate the A-a gradient?

1. Calculate the pressure of inspired O2
2. Use PIO2 along with PACO2 and PaO2 to calculate A-a gradient


What is the cause of hypoxemia most commonly in the case of lung fibrosis?

V/Q mismatch due to destruction of both capillaries and alveoli


High ventilation rates can compensate for low V/Q ratio units for _____ but not _______

CO2 but not O2


How does alkalosis cause the oxyhemoglobin curve to shift?

to the left (greater Hgb-O2 affinity which is good for pick up but does not help for off-loading in the tissues)


What's a good rule of thumb that helps to estimate the contribution of alveolar hypoventilation to hypoxemia?

alveolar hypoventilation is approximated by the excess of PaCO2 over 40mm Hg


100% oxygen is a very sensitive way of measuring ____ ____.

anatomic shunts, a small decrease in O2 content due to a true stung causes a large decrease in PaO2 that is easily measured


How can you rule out an anatomic shunt?

PaO2 at or greater than 550 on 100% can rule out a shunt, note if PaO2 is less than 550, that does not identify a shunt with certainty