65 year old man with altered mental state and brain mets with

1.

acute respiratory acidosis

associated anion gap metabolic acidosis – elevated lactate, BE -5

HCO3 normal due to partial compensation – delta gap <0.4, ??possible non anion gap metabolic acidosis as well

triple acid base disorder – HAGMA, NAGMA, Resp acidosis

2.

Results consistent with seizure as possible cause, additional causes of HAGMA and NAGMA should be sought

3.

In Summary:

Establish boundaries of care

ABC approach

urgent CT head – acute raised ICP due to oedema, haemorrhage, further mets to brain, other

Seek and treat cause, including sepsis, dehydration, exacerbation of COPD etc.

This patients repeat gas 1 hour later:

pH  7.32

pCO2  56

Lactate  5.7