Comparative Analysis of Signal Accuracy of Three SpO2 Monitors During Motion and Non-Motion Conditions

Pulse Oximetry is the standard of care for assessing oxygen saturation in the acute care setting.¹ Motion artifact degrades pulse oximeter performance and represents a clinical challenge.² Manufacturers have developed pulse oximeter technologies to minimize the impact of motion on sensor performance

Comparative Analysis of signal accuracy motion and non-motion conditions

Background

Pulse Oximetry (SpO2) is the standard of care for assessing oxygen saturation in the acute care setting¹
Motion artifact degrades pulse oximeter performance and represents a clinical challenge²
Manufacturers have developed pulse oximetry technologies to minimize the impact of motion on sensor performance

Objectives

A comparative study was conducted to evaluate SpO2 accuracy of three currently available devices: GE CARESCAPE TruSignal, Masimo RADICAL-7 and Medtronic Nellcor PM1000N, during motion and non-motion conditions.

Methods

After University of California San Francisco IRB approval, healthy adult (≥18 years) volunteer non-smokers with normal Hgb levels were recruited for this prospective, open-labeled study
Testing was conducted using a minimum of 10 subjects, including ≥2 subjects with darkened skin pigment (FDA Pulse Oximetry Guidance (2013) & ISO 80601-2-61:2017)
Skin pigmentation was conducted using a categorized by the Fitzpatrick scale
All 3 pulse oximeters were placed on both hands (one hand was motion and one was non-motion), using a randomized, counter-balanced approach for SpO₂ finger placement to control for order bias
The non-motion hand had an arterial catheter used for sampling reference co-oximetry oxyhemoglobin (SaO2) measurements
SpO₂ readings from the 3 devices on the motion hand were compared to SpO₂ readings from the corresponding devices on the non-motion hand
Data were collected using three motion conditions (tapping, rubbing, clenching) and under 3 oxygenation conditions (room air, oxygen desaturation to <90%, and re-saturation phase)
Descriptive data for comparison included the Accuracy Root Mean Square (ARMS), bias, and absolute delta (AD)

Results

Fig. 1: SpO₂ Accuracy (ARMS) vs SaO₂. Non-motion by SaO₂ ranges
Fig. 2: SpO₂ Bias vs SaO₂. Non-motion by SaO₂ ranges
Fig. 3: SpO₂ Accuracy vs. SaO₂. All motion types by SaO₂ ranges
Fig.4: SpO2 Bias vs SaO₂. All motion types by SaO₂ ranges

Discussion and Conclusions

The study sample (N=14) included 9 male and 5 female subjects, with a mean age of 28.1 years (SD=5.3) and a range of 24-43
Skin tones varied by the Fitzpatrick scale as Type II (N=1), Type III (N=6), Type IV (N=5), Type V (N=1), and Type VI (N=1). Ethnicity was Asian (N=5), Caucasian (N=5), Hispanic (N=2), Black (N=1), and Multiethnic (N=1)
In non-motion conditions, mean AEMS (Fig. 1) for the 3 devices across all saturation phases, were 1.35 (GW), 1.58 (Masimo) and 2.51 (Nellcor), with overall mean bias (Fig.2) of -041,(Masimo), 0.44(GE), and 0.90 (Nellcor)
During motion conditions, mean ARMS (Fig 3.) were 1.81 (GE), 3.43 (Masimo) and 4.52 (Nellcor), with overall mean bias (Fig.4) of -0.92 (Masimo), 0.08 (GE), and -0.13 (Nellcor)
The AD5 for all saturation levels was 4.7%(GE), 7.9% (Masimo), and 16.3% (Nellcor). AD10 WAS 0.8% (GE), 3.0% (Masimo), and 5.8% (Nellcor)
Under 3 simulated conditions for both motion and oxygenation, the Nellcor, GE, and Masimo pulse oximetry technologies demonstrated comparable performance, with no single device having the best measurements under all conditions
The clinical relevance of these results requires further study during actual clinical use

Directions for further study

Evaluation of the technologies during clinical care under various measurements conditions
Subgroup analysis based on skin pigmentation levels
Analysis for statistically significant differences between technologies

References

ASA. (2020). Standards for Basic Anesthetic Monitoring, In. ASA Standards and Guidelines: Committee on Standards and Practice Parameters (CSPP). https://www.asahq.org/standards-and-guidelines/standards-for-basic-anesthetic-monitoring. Accessed 9 August, 2022
Louie, A, Feiner, J-R-, Bickler, P.E., Rhodes, L., Bernsteing, M., & Lucero, J. (2018). Four Types of Pulse Oximeters Accurately Detect Hypoxia during Low Perfusion and Motion. Anesthesiology, 128(3), 520-530. https://doi.org/10.1097/aln.0000000000002002

Disclosures

JB and SL are employees of GE Healthcare

RB and KG have received consulting fees from GE Healthcare