Is "3rd order" "2nd order" the new buzz words? I hear them a whole lot especially from people taking step.
I would hope somebody entering medical school would at least have some curiosity and respect from the people who have been there and taken the test in question. I'll try to explain..
1st order question: What are the expected bicarb levels, pH, and pCO2 in a respiratory alkalosis? (they give you a bunch of numbers to choose from and you pick it). You may get something like this in 2nd year, but honestly, I'd say it's a crappy question.
2nd order question: The patient comes in with these acid base numbers disturbances, what do they have (ie. resp alk, metabolic alkalosis, metabolic acidosis, mixed, etc.)? (only seen really in first or early second year)
3rd order question:
An anxious young woman presents to the emergency department because of acute-onset severe abdominal pain. She consumed eight or nine alcoholic drinks earlier in the evening. She also admits to using diuretics to "lose water weight." Physical examination reveals periumbilical tenderness to palpation. Her stool is guaiac negative. Arterial blood gas analysis reveals a pH of 7.55, a bicarbonate level of 21 mEq/L, and a partial pressure of carbon dioxide of 25 mm Hg. Her sodium level is within normal limits. Which of the following is the most likely cause of her acid-base disturbance?
A. An accumulation of unmeasured anions as a result of hepatic metabolism of alcohol
B. Electrolyte imbalance due to diuretic use
C. Hyperventilation secondary to pain and anxiety
D. Hypoventilation due to the respiratory depression caused by alcohol ingestion
E. Vomiting due to alcohol toxicity
The answer is C. She's got a respiratory alkalosis and is blowing off CO2 cause of her pain (probably pancreatitis but it doesn't really matter). You're supposed to ignore the other crap, recognize the respiratory alkalosis in the numbers and that it is often associated with pain (especially abdominal) answer and move on.
