Certified Transport Registered Nurse Certification Practice Exam

Which term is synonymous with pulse oximetry?

1. SpO2

2. PaO2

3. Capnography

4. Arterial blood gas

The correct answer is: SpO2

Pulse oximetry is a non-invasive method used to measure the oxygen saturation level in a person's blood, which is typically expressed as SpO2. This term specifically refers to the oxygen saturation measured by a pulse oximeter, indicating the percentage of hemoglobin molecules in arterial blood that are saturated with oxygen. In contrast, PaO2 refers to the partial pressure of oxygen in arterial blood, which is obtained through an arterial blood gas test and provides information about the oxygen dissolved in the plasma, rather than saturation. Capnography monitors the concentration of carbon dioxide in exhaled air, thus measuring ventilation rather than oxygen levels. Arterial blood gas analysis is a more comprehensive method that assesses the levels of oxygen, carbon dioxide, and pH in the arterial blood, but again, it does not specifically assess saturation in the same manner as pulse oximetry does. Therefore, SpO2 is the appropriate synonym for pulse oximetry, as it directly correlates with the measurement obtained from a pulse oximeter.