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* nbme 7q
  toyonaka - 04/20/15 11:28
  A 16-year-old girl is brought to the emergency department after her parents found her comatose next to a suicide note. On arrival, she is unresponsive. Her temperature is 37.2C(99F), pulse is 100/min, respirations are 28/min, and blood pressure is 100/66 mmHg. Examination shows pupils reactive to light, a doll's eye reflex is present. Laboratory studies show:
Na 140
Cl 104
K 3.5
HCO3 6

Arterial blood gas analysis on room air:
pH 7.32
PCO2 12
PO2 92

Which of the following is the most likely substance used in her suicide attempt?

A) Acetaminophen
B) Aspirin
C) Diazepam
D) Heroin
E) Methanol

Can anyone explain?
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* Re:nbme 7q
  drpardha - 04/20/15 12:29

Metabolic acidosis

high anion gap

(Na+ + K+) - (Cli- + HCO3-).

Here it is

(140+3.5)-(104+6) = 33.5

Also low bicarbonate & low PCO2

So metabolic acidosis

Pneumonic for metabolic acidosis is


M- Methanol
D-Diabetic KA
P-Propelene Glycol
L-Lactic Acidosis
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* Re:nbme 7q
  toyonaka - 04/20/15 12:35
  Thx, I had difficulty in choosing between B & E, either one seems correct, can u help me more?  
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* Re:nbme 7q
  monter - 04/20/15 13:14

to differentiate between those two,

use winter's formula.

6+3+8 = 17 plus minus 2 , range 15 to 19.

That is where Pco2 should be if only met acidosis.

So, there is resp alcalosis present too.

Aspirin will cause resp alc first and then met acidosis.
(so, it is past 4 hours, since she took the pills, that si when acidosis kicks in)

correct me if wrong.

thank you.
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* Re:nbme 7q
  toyonaka - 04/20/15 13:42
  Thx, very reasonable. I got E wrong.  
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* Re:nbme 7q
  docboss - 05/14/18 21:25
  diazepam would decrease respirations not increase them so that differentiates between b and c. answer is b  
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* Re:nbme 7q
  docboss - 05/14/18 21:27
  additionally aspirin or amino salicylic ACID causes an anion gap metabolic acidosis and increases respiratory drive at the same time so you get metabolic acidosis and respiratory alkalosis - so b is def the answer  
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