Abstract
Pulse oximetry is the most commonly used piece of monitoring equipment in general practice. It gives non-invasive objective information on oxygenation and pulse rate and subjective information on pulse quality. Like all electronic anaesthetic monitoring devices pulses oximeters can be used to improve the safety of anaesthesia; however, over-reliance on their use has a number of pitfalls. Foremost is the potential for erroneous measurement. Poor pulse quality, light interference, movement, pigmented tissue can all effect the accuracy and reliability of pulse oximetry. Understanding how the pulse oximeter works and how to assess signal quality is vital if pulse oximeters are to be used in an appropriate fashion. This allows the anaesthetist to ensure that the readings being given and recorded are realistic, which in turn helps decision making and ensures timely intervention.
Multiple Choice Questions
1. | Pulse Oximetry measures which of the following:
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2. | In the McMillan & Darcy, 2016 study how many patients showed significant oxygen desaturation?
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3. | Which of the following drugs commonly used in anaesthetic premedication may interfere with perfusion and therefore pulse oximeter readings?
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4. | Methaemoglobin may be caused by which type of poisoning?
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5. | The two common types of pulse oximetry are:
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6. | What is the ‘penumbra effect’?
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7. | Which of the following does NOT typically cause altered absorption when utilising pulse oximetry?
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8. | When is measuring SpO2 most useful?
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9. | If SpO2 is 95% what is the approximate expected PaO2?
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10. | If an abnormal reading is detected on pulse oximetry, which of the following is the least appropriate action?
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Additional information
Notes on contributors
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Matthew McMillan
Matt runs the clinical anaesthesia service at the Queen’s Veterinary School Hospital. He is a European and RCVS recognised specialist in Veterinary Anaesthesia and Analgesia. His main interests include patient safety, especially pertaining to anaesthesia, medical error and veterinary education. He led the team that developed the Association of Veterinary Anaesthetist’s Anaesthetic Safety Checklist.