Thursday, January 22, 2009

Day #196 - Confusion

The blogs this month are short because I am on clinical service...

We've previously discussed an approach to acute confusion here.

Today we talked about a 83 year old woman with underlying cognitive impairment with acute confusion. When I hear this stem, I think "what have we, as doctors, done iatrogenically to cause this" because this is probably one of the most common causes.

In this case the patient had a metabolic acidosis, with a wide anion gap. The differential diagnosis includes "MUDPILES". In this case, it was probably a combination of uremia/renal failure and starvation ketoacidosis.

M - methanol poisoning
U - uremia
D - diabetic ketoacidosis/alcoholic ketoacidosis/starvation ketoacidosis
P - paraldehyde
I - iron/INH overdose
L - lactic acidosis: type A (tissue hypoperfusion or ischemia) type B (failure of liver to clear lactate (i.e. liver failure, metformin toxicity, beri-beri)
E - ethylene glycol
S - salicilates

One can calculate the osmolar gap to look for osmotically active compounds (such as the toxic alcohols).

Osmolar gap = measured osmoles - [2xNa + glucose + urea]
normal <10>

Remember, that sometimes in later stage toxic alcohol poisoning the osmolar gap may be normal despite significant toxicity. See this case.

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