The retainer who got worse

core

A 70-year-old with severe COPD, drowsy on arrival with a chest infection. His clinic letters mention 'chronic CO2 retention'.

Blood gas

pH7.26

PaCO278 mmHg

HCO334 mmol/L

PaO248 mmHg

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.