Q; 30-year old patient with history of diabetes, presented to the hospital with c/o nausea and vomiting. Patient 

sodium was 140meq/l, 
potassium was 4meq/l, 
chloride was 105meq/l, 
HCO3 was 5meq/l. 

 On ABG 

pCO2 was 16 and 
pH was 7.11. 

 What is the acid base disturbance? 

 A) Metabolic acidosis 
 B) Respiratory acidosis 
 C) Mixed metabolic and respiratory acidosis 
 D) Triple acid-base disturbance 



Answer: A 

 Rationale: Patient anion gap is high (30) suggestive of metabolic acidosis. Patient CO2 is low, not supporting the notion of respiratory acidosis. Expected CO2 is (pCO2=1.5(HCO3) +8 +/-2; 1.5x5+8+/-2=13.5-17.5) within normal range.