Blood Gas Analysis
When is ABG useful to investigate oxygenation?
Almost never. For patients with an adequate oximetry waveform, pulse oximetry is usually superior to ABG for measuring oxygenation. ABG is only useful to investigate oxygenation when:
- Pulse oximetry waveform is unreliable.
- Diagnosis of methemoglobinemia.
- Calculation of the PaO2/FiO2 ratio to guide a specific therapeutic decision.