msyamp
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ACUTE HYPOVENTILATION LIKE IN NEAR DROWNING. AM I RIGHT??
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| Rasul
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Guess so.
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| determine
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3?
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| drdeerajnathl
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Inc. A-a is in anemia
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| achilles
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anaemia
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| ruhighazi
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Causes of increased (A-a) difference:
Alveolar collapse(atelectasis), Intaalveolar filling(pneumonia, pulmonary edema), Intracardiac shunt, Vascular shunt within lungs, Asthma, COPD, ILD, Aleolar dz, Pulmonary vascular dz
So the answer is ASTHMA
Hypoventilation alone can't produce increased (A-a) diff
Hemoglobin level has an ignorable effect on (A-a) diff
In high altitude the inspired O2 is decresed so the (A-a)diff has no increase
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Ruhighazi
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| achilles
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thanks ruhighazi. yes asthma should be the answer. Aa gradient surely also increases in asthma.
but i am still wondering about this - even in anaemia should'nt the Aa gradient be increased too as the 02 carrying capacity of the blood is reduced so the difference in the alveolar and arterial oxygen should only increase. or is the increase not so much ?
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| achilles
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i'm just bringing this to the top of the page so that this post doesnt go to the next page and someone can answer this. wow...its been a good discussion today morning. thanks everyone, this has beeb really helpful.
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| alenka
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Aa gradient gets increased if there's an obsticle on the way of O2.
so in hight altittude-low O2 pressure-so what?the oxygen is still getting to the lungs but the Aa gradient is not increased.
in hypoventilation(like in barbiturate poisoning)-you still get all the oxygen you inhale into the lungs-so Aa gradient is OK.
in anemia-you have only few RBCs-but they still do they job-carry O2.
in sthma-there's pulmonary edema,inflammation,mucus secretion-lots of cr..p for oxygen to get through,so there's a difference-you don't get all the oxygen you inhale into the lungs.
maybe some things were not precise-but the in general i guess it makes scense.
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| thalamus00
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in anemia you have decreased RBCs, but carrying capacity is normal. therefore you have decreased O2 content buy oxigen Saturation is normal. i think thats why A-a gradient is normal.
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| jvo_md
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High altitude? maybe...
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| achilles
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thanks thalamus.
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| rman
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The answer is asthma for reasons discussed above. However, severe anemia can cause an increase in the A-a gradient because: anemia->decrease viscosity-> decrease in resistance->increase in CO->decrease transit time between start and end of pulmonary capillary-> and increase in A-a gradient. But I gather that the anemia has to be pretty bad to get into high output cardiac failure to see this.
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| achilles
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thanks alenka and rman.
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