SpO2 Quiz: Can You Read the Pulse Oximeter?

1. What is the normal SpO2 range for a healthy adult at sea level?

85–92%

95–100%

88–95%

100–110%

2. Which site is preferred for pulse oximetry sensor placement in adults?

Earlobe

Index finger

Great toe

Forehead

3. Pulse oximetry measures oxygen saturation by detecting light absorption. What does SpO2 represent?

Arterial oxygen pressure

Percentage of hemoglobin saturated with oxygen

Total oxygen content in blood

Venous oxygen saturation

4. A patient's SpO2 is 88% on room air. This reading is considered:

Normal

Mildly hypoxemic

Severely hypoxemic

Hyperoxemic

5. Which wavelengths of light does a pulse oximeter use to measure saturation?

Ultraviolet and infrared

Red and infrared

Green and blue

Visible and microwave

6. Carbon monoxide poisoning can cause falsely elevated SpO2 readings because:

CO increases hemoglobin oxygen binding

Carboxyhemoglobin absorbs light similarly to oxyhemoglobin

CO blocks infrared light detection

CO reduces sensor sensitivity

7. A pulse oximeter displays a poor waveform and unreliable reading. Which factor is least likely responsible?

Peripheral vasoconstriction

Patient movement artifact

Normal sinus rhythm

Low perfusion state

Submit

9. True or False: Pulse oximetry can reliably detect hypoxemia in a patient with severe anemia.

True

False

10. Which condition causes falsely low SpO2 readings on pulse oximetry?

Hypothermia with peripheral vasoconstriction

Elevated hemoglobin

Fetal hemoglobin presence

Increased cardiac output

11. A patient on supplemental oxygen has an SpO2 of 92%. Their PaO2 is most likely:

45–55 mmHg

55–70 mmHg

80–100 mmHg

>100 mmHg

12. The pulse oximeter's plethysmographic waveform indicates:

Blood pressure and heart rate

Perfusion quality and pulse strength

Oxygen consumption rate

Hemoglobin concentration

13. Nail polish and artificial nails can interfere with pulse oximetry readings because they:

Increase sensor temperature

Absorb light wavelengths used by the sensor

Reduce blood flow to the finger

Increase hemoglobin saturation

14. In acute respiratory distress syndrome (ARDS), a patient's SpO2 is 94% on a non-rebreather mask. This suggests:

Adequate oxygenation

Significant hypoxemia despite supplemental oxygen

Possible measurement error

Resolved respiratory failure

15. Fetal hemoglobin (HbF) has a higher oxygen affinity than adult hemoglobin. How does this affect pulse oximetry readings?

Readings are falsely elevated

Readings are falsely decreased

Readings are unaffected

Readings alternate unpredictably