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Hyperchloraemic Acidosis Saline Infusion — FRCA Final MCQ

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ModerateGeneral AnaesthesiaHyperchloraemic Acidosis Saline InfusionFRCA Final

A patient undergoing GA receives a total of 2 L of 0.9% NaCl during a 3-hour procedure. Postoperative bloods show Na 145, Cl 112, pH 7.28, HCO3 18. What acid-base disturbance has this infusion caused?

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Correct answer: D — Normal — expected findings

Large-volume 0.9% NaCl infusion causes hyperchloraemic metabolic acidosis (non-anion-gap). NaCl has supraphysiological chloride (154 mmol/L vs plasma 96-106), reducing the strong ion difference → acidosis. This is why balanced crystalloids (Hartmann's, Plasmalyte) are now preferred for large-volume resuscitation.

Reference: NICE – 2017 – CG174 IV fluid therapy in adults