Archive for August 27th, 2010

What is a Pulse Oximeter?

To begin, it is a source of light that originates from the probe at two wavelengths (650nm and 805nm). The light is partly absorbed by haemoglobin (iron-containing and oxygen transporting metalloprotein in red blood cells).

What do they measure?
Arterial blood oxygen saturation by sensing absorption properties of deoxygenated and oxygenated hemoglobin using various wavelengths of light.

A basic meter includes a sensing probe attached to a patient’s earlobe, toe, finger, or other body locations, and data acquisition system for the calculation and display of oxygen saturation level, heart rate, and blood flow. Pulse oximetry is one of the most commonly employed monitoring modalities in the critical care setting.

Pulse oximeters may be used in a variety of situations but are of particular value for monitoring oxygenation and pulse rates throughout anaesthesia. They are also widely used during the recovery phase.

The oxygen saturation should always be above 95%. In patients with long-standing respiratory disease or those with cyanotic congenital heart disease readings may be lower and reflect the severity of the underlying disease.

Causes of interference in your pulse oximetry ready include:

  • Nails: dark-colored nail polish, false or thickened nails can hinder an accurate reading.
  • Electrical: radio frequencies
  • Movement: seizer or shivering
  • Edema: if present in the area the test is being held

You may need to use a Pulse Oximetry for an overnight Sleep Screening to determine Obstructive Sleep Apnea (OSA). For more information on OSA please visit:

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