Identification of movement artefact by the Nellcor N-200 and N-3000 pulse oximeters

The Nellcor N-3000 pulse oximeter is designed to be able to identify signal artefact related to movement of the body part to which the probe is attached. It may therefore provide a reliable means of monitoring arterial oxyhemoglobin saturation (SpO2) in awake, moving patients. This study compared the Nellcor N-3000 and N-200 pulse oximeters in terms of their ability to identify readings associated with movement, in a group of volunteers making standardized movements.

Thirty-six volunteers were studied. Volunteers breathed room air throughout the study. SpO2 of each volunteer was monitored by both a Nellcor N-200 and a Nellcor N-3000 simultaneously on both hands. Volunteers made a series of five standardized movements, each lasting one minute, with each hand during the monitoring session, while SpO2 and oximeter status were recorded from all four oximeters. The mean SpO2 reading was calculated during each movement. SpO2 readings which the oximeter identified as being associated with movement, pulse search not locked, sensor not attached, or break in communications were excluded from analysis.

The N-3000 rejected from 17 to 78% of readings taken during movement, compared to 0 to 2% with the N-200. Although the remaining readings of both types of oximeters were subject to some movement artefact, which led to spuriously low SpO2, this was significantly less with the N-3000.

The Nellcor N-3000 pulse oximeter is able, to some extent, to identify movement artefact. It should offer an advantage over the N-200 when monitoring moving patients.