High nasogastric suction tubes output, severe hypokalemia and acid-base disorder

Q: High output via nasogastric suction tubes in ICU patients may result in severe hypokalemia and which acid-base disorder?  

A) Metabolic acidosis
B) Respiratory acidosis
C) Metabolic alkalosis
D) Respiratory alkalosis
E) Triple acid base disorder


Answer: C

Severe hypokalemia results in metabolic alkalosis due to an intracellular shift or loss of hydrogen ion. This is chloride-responsive metabolic alkalosis, means it can be suspected if urine chloride is < 10 mEq/L. 

In ICU, high output via nasogastric suction tubes is the most common cause of severe hypokalemia due to loss of hydrochloric acid (H+ and Cl-). Concomitant hyponatremia leads kidney to compensate by retaining sodium in the collecting ducts at the expense of hydrogen ions.

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#gastroenterology
#nephrology


Reference:

Hennessey, Iain. Japp, Alan.Arterial Blood Gases Made Easy. Churchill Livingstone 1 edition (18 Sep 2007).