SpO2 and PaO2 are both indicators of oxygenation, aren't they? The barrier to entry is likely lower for SpO2, isn't it? From clinics to hospitals, from outpatient to inpatient care, and furthermore, ...

Have you ever heard things like this? "If SpO2 drops below 90%, PaO2 is below 60 mmHg (Torr), so respiratory failure is occurring." "SpO2 below 90% is dangerous, so oxygen therapy is necessary." "How ...