Pulse Oximetry Technique

Updated: Sep 02, 2015
  • Author: Bruce M Lo, MD, MBA, CPE, RDMS, FACEP, FAAEM, FACHE; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Technique

Approach Considerations

There are several approaches to pulse oximetry. When properly attached, the ideal plethysmograph waveform shows a dicrotic notch (see image below).

Pulse oximetry with normal plethysmograph waveform Pulse oximetry with normal plethysmograph waveform.

Digit approach

This is the preferred method. The transmission probe is placed on the end of a digit, usually the finger, with the emitter on one side and the sensor on the opposite side (see image below). The digit should be resting comfortably and out of excessive light. The probe is then connected to the monitoring unit.

Portable pulse oximeter with finger probe. Portable pulse oximeter with finger probe.

Excessive debris should be removed prior to probe attachment, as well as any nail polish or artificial nails.

Ear approach

A transmission probe is placed on the end of an ear lobe with the emitter on one side and the sensor on the opposite side (see image below). The probe is then connected to the monitoring unit.

Pulse oximeter probe on ear. Pulse oximeter probe on ear.

Palm/foot approach in neonates

In neonates, in whom the digit or ear may be too small, a transmission probe may be placed over the palm or foot. The probe is then connected to the monitoring unit.

Forehead approach

A reflectance probe should be placed low across the forehead right above the eyebrows and away from a major vessel (see the images below). The patient should be resting in an inclined position. A headband around the probe and across the forehead should also be placed. The probe is then connected to the monitoring unit.

Two components for forehead blood oxygen saturatio Two components for forehead blood oxygen saturation (SpO2) sensor (Nellcor™ SpO2 Forehead Sensor).
The sensor is placed on the forehead of the patien The sensor is placed on the forehead of the patient.
The headband is placed to secure the sensor probe. The headband is placed to secure the sensor probe.