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NBME 21 Answers

nbme21/Block 2/Question#9

A 40-year-old man is brought to the emergency ...

Metabolic acidosis and respiratory acidosis

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 +2  upvote downvote
submitted by mcl(167),

When working on acid/base disorders, it helps to look systematically at the following: (1) pH (which sadly was not given in this problem), (2) figure out which problem is primary by looking at PaCO2 and bicarb, and (3) look for any compensation (which the question doesn't ask but still).

Here, we see that the CO2 is high on the ABG. This means that patient is hypoventilating since levels of CO2 are ventilation dependent, and also that patient has respiratory acidosis. Also, bicarb is low, which implies that it's being "soaked up" by metabolic acidosis.

privatejoker  I just look at these as "what makes the most sense" and this is is sufficient in nearly every scenario. Out of the given options, the only explanation that even lines up with the given numbers is the answer choice. +  

 +0  upvote downvote
submitted by usmle11a(2),

i did the

(Hco3-)x1.5 +8 +-2

it should CO2 that is wat higher than compensation indicating mixed

another way is the ↑ ↓ way


 -2  upvote downvote
submitted by dr.xx(34),

Henderson-Hasselbach Equation: pH = 6.1 + log(HCO3 / (0.03 * PaCO2)); so here, pH = 6.92 => Acute (uncompensated) primary respiratory acidosis, with metabolic acidosis

sbryant6  calculator can't do logs yo. +