Pulse Oximetry

Introduction

Pulse oximetry measures peripheral arterial oxygen saturation (SpO₂) as a surrogate marker for tissue oxygenation. It has become the standard for continuous, non-invasive assessment of oxygenation.

• Pulse oximetry uses spectrophotometry to determine the proportion of haemoglobin that is saturated with oxygen (i.e. oxyhaemoglobin) in peripheral arterial blood.

How to Use a Pulse Oximeter

NOTES:

• Make sure the finger you are going to use (index finger or middle finger) does not have any nail varnish or a false nail on it.
• The best reading is achieved when your hand is warm, relaxed and held below the level of your heart.
• Skin pigment can impact the accuracy of pulse oximetry. Recent studies show that in those with darker skin pigments, pulse oximetry may miss below-normal oxygen saturations.
• Motion can induce considerable error into pulse oximetry accuracy, resulting in loss of data, inaccurate readings, and false alarms.
• If you smoke, the reading on your oximeter may be higher than your actual oxygen saturation. This is because smoking increases carbon monoxide levels in your blood, and the oximeter cannot tell the difference between the gas carbon monoxide from oxygen.

External Links

• UpToDate - Pulse Oximetry
  
• Pulse Oximeter Accuracy and Limitations: FDA Safety Communication
  
• Using a pulse oximeter to check you are OK - NHS England
  
• Pulse Oximetry - American Thoracic Society
  
• Effects of Skin Pigmentation on Pulse Oximeter Accuracy at Low Saturation, 2005
  
• Dark skin decreases the accuracy of pulse oximeters at low oxygen saturation: the effects of oximeter probe type and gender, 2007
  
• The Effect of Motion on Pulse Oximetry and Its Clinical Significance, 2007
  
• Accuracy of Smartphone Pulse Oximeters in Patients Visiting an Outpatient Pulmonary Function Lab for a 6-Minute Walk Test, 2019