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Dunce

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May 15, 2006
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Example: gastric outlet obstruction or pyloric stenosis

Can somebody explain this electrolyte abnormality in terms that make sense and are also correct?
I understand it, at least I think I do. However, I keep hearing slightly conflicting explanations about the renal compensations going on.

P.S. -- this is a super highly pimped topic in my experience
 

OncoCaP

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Aug 28, 2006
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Example: gastric outlet obstruction or pyloric stenosis

Can somebody explain this electrolyte abnormality in terms that make sense and are also correct?
I understand it, at least I think I do. However, I keep hearing slightly conflicting explanations about the renal compensations going on.

P.S. -- this is a super highly pimped topic in my experience

Is this the kind of explanation you are looking for:

http://www.emedicine.com/ped/topic1114.htm
http://www.emedicine.com/PED/topic1121.htm
 
N

njbmd

Example: gastric outlet obstruction or pyloric stenosis

Can somebody explain this electrolyte abnormality in terms that make sense and are also correct?
I understand it, at least I think I do. However, I keep hearing slightly conflicting explanations about the renal compensations going on.

P.S. -- this is a super highly pimped topic in my experience

How about this one:

Pyloric stenosis is results from hypertrophy of the circular muscle of the pylorus. This in turn results in gastric outlet obstruction from the constricted circular muscle. The gastric outlet obstruction then causes non-bilious, projectile vomiting (hallmark of the diagnosis of pyloric stenosis) which depletes hydrochloric acid from the stomach. This depletion of hydrochloric acid causes a hypocholemic metabolic alkalosis and dehydration because of the loss of H+ and Cl- ions in addition to fluid. Renal compensation for this loss of H+ ions is by preserving protons at the expense of potassium and thus hypokalemia ensues with now, hypochloremic, hypokalemic metabolic alkalosis.

If correction is not undertaken, H+ will begin to be excreted in the urine with the develpment of the "paradoxical aciduria". Respiratory compensation for the metabolic alkalosis is respiratory acidosis (think prone to apnea here) so these children should have electrolyes and hydration status corrected as soon as possible.

Before surgery, the dehydration should be corrected slowly with administration of saline (half-normal) given without potassium until the intravascular volume is restored (get the urine output adequate). Once the intravascular volume is restored, you can add potassium to correct the potassium deficit. The serum bicarbonate level should also be normalized before surgical correction by laparoscopic or open pylomyotomy.

I hope that this helps.
 
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N

njbmd

I imagine he was looking for more detail. :smuggrin:



j/k :p did you just type all that out?


Just came off being chief on peds surgery a few months ago. Got pimped on this myself (the development of paradoxical aciduria part). Yes, even the chiefs get pimped too :scared:
 
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