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Retired NBME Free 120 Answers
mikerite
Based on the correct answer choice, the person is now in metabolic acidosis with respiratory compensation.
+5
bwdc
The correct answer choice is as listed above (all decreased). Note that whether metabolic acidosis is combined with primary respiratory alkalosis, which is an important teaching point I’ve argued the question writers are probably getting at, or even if just simple respiratory compensation for metabolic acidosis–both can have the same arrows. In this case, it’s not respiratory compensation. In ASA overdose, the respiratory alkalosis actually happens first. Ultimately, the metabolic acidosis dominates and the pH is almost always low. This mixed primary acid/base response to ASA toxicity is highly testable.
+2
ali
How long till the respiratory alkalosis turns into a metabolic/mixed picture?
+3
bwdc
@ali 12 hours is a good number to memorize but it can definitely happen much earlier.
+1
yoav
From what I understand, the metabolic acidosis only presents 12h post ingestion, while she is only 3h. What do you think?
+2
bwdc
@yoav, It can definitely happen earlier. It’s more of a by 12 hours (not only beginning then).
+1
angelaq11
I'm beginning to think that they don't actually care about how many hours lapse after the ingestion, but if we actually know the unique acid-base disturbance. I chose the wrong one, again because I was foolishly thinking about those 12 hours postintoxication
+7
charcot_bouchard
I think this is good rule of thmb in USMLE "a Right answer may or may not tick all the correct things but will NEVER have a wrong thing in it". So the ans choice we all chose has Bicarb inc. But this will never happen. at 3 hour we should have pure resp alkalosis with normal bicarb (as per uw). Or in this case decreased due to neutralization by organic salicylic acid. In Aspirin poisoning bicarb will nver increase.
+7
elasaf@post.bgu.ac.il
Another important point- they probably gave her RR (30) to indicate that she is hyperventilating==> LOW CO2
+3
submitted by ∗bwdc(697)
Memorize aspirin’s unique acid-base effects: metabolic acidosis and respiratory alkalosis. Note, this is likely actual respiratory alkalosis, not simply normal respiratory compensation for metabolic acidosis.