A normal pH, and nothing else normal

advanced

A 44-year-old with alcohol use disorder, three days of vomiting, now febrile and unwell with epigastric pain. The resident notes with relief that the pH is normal.

Blood gas

pH7.40

PaCO230 mmHg

HCO318 mmol/L

Na137 mmol/L

Cl92 mmol/L

K3.2 mmol/L

Lactate6.1 mmol/L

Albumin38 g/L

No high/low cues on purpose: read the numbers the way the gas machine prints them.

Stepwise interpretation

Commit to your own read first: pH, primary process, compensation, gap, delta, oxygenation. Then walk the engine’s steps and see where you agree.