A patient in the ICU has begun breathing in deep, rapid respirations (Kussmaul's respirations). The nurse knows that this is associated with which of the following lab findings?

Anion gap >18 mmol/L
HCO3 < 21
pH < 7.35

Explanation

•The rapid, deep breathing of Kaussmaul's respirations are a compensatory mechanism to try to eliminate acid in the form of carbon dioxide when the body is in metabolic acidosis. 

•To distinguish between the main types of metabolic acidosis, the anion gap is calculated by subtracting the sum of the chloride and bicarbonate levels from the sum of the sodium and potassium levels. Normally, this concentration is about 8-16 mmol/L. An elevated anion gap (i.e. > 16 mmol/l) can indicate particular types of metabolic acidosis, particularly certain poisons, lactate acidosis and ketoacidosis.

•Anion gap = ( [Na+] + [K+] ) − ( [Cl−] + [HCO3−] )

Reference ranges:

pH: 7.35–7.45

pCO2: 35–45

HCO3: 21–28

pO2: 80–100

Anion gap: 8-16 mmol/L

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