Chapter 5: Oxygen Therapy

5.3 Pulse Oximetry

Critical Thinking Exercises: Questions, Answers, and Sources / References

  1. You are checking your patient’s SpO2 but the signal strength on the pulse oximeter is poor. What would be your next steps?
  • Answer: check the patient’s limbs for warmth then either warm them or find a new location. Check for low cardiac output potentially due to hypovolemia, cardiac problems or septic shock. All of these require immediate attention. Remove any nail polish that might be interfering with the reading. Shield the oximeter from bright light.

Source: World Health Organization. (2011). Pulse oximetry training manual.


  1. Your patient is admitted with a diagnosis of carbon monoxide poisoning with an SPO2 of 98%. What does this reading tell you?

Answer: CO can bind to the hgb and is read as O2 and as such the pulse oximetry reading is inaccurate.

Source: Howell, M. (2002, March). The correct use of pulse oximetry in measuring oxygen status. Nursing Times