Exploring the impact of pulse oximeter selection within the COVID-19 home-use pulse oximetry pathways

Determining factors of pulse oximetry accuracy: a literature review

OBJECTIVE

Identify and reach consensus on the variables that affect the measurement of oxygen saturation using pulse oximetry.

METHODS

We applied inclusion and exclusion criteria to select relevant studies in databases such as Ebsco and PubMed. The search strategies, carried out until December 2023, focused on publications that addressed the technology of pulse oximeters and variables that influence their accuracy. We assessed the risk of bias of the included studies and used standardized methods for synthesis of results.

RESULTS

23 studies were included. The synthesis of the results highlighted that equipment with tetrapolar technology showed greater precision in oxygen saturation measurements. Increased skin pigmentation, hemoglobinopathies and high skin temperatures can lead to an overestimation of SpO2, while factors such as low perfusion, cold skin temperature, nail polish or tattoos, hypoxemia, anemia and high altitude training, they may underestimate it. On the other hand, motion artifacts, light pollution, frequency >150 beats per minute, electromagnetic interference and location of the sensor can cause distortion of the photoplethymography signal.

CONCLUSIONS

The synthesis of the results highlighted that skin pigmentation and light interference can lead to an overestimation of SpO2, while other factors such as low perfusion and altitude tend to underestimate it. The studies presented variability and heterogeneity in their designs, evidencing limitations in the consistency and precision of the evidence. Despite these limitations, the results underscore the importance of considering multiple variables when interpreting pulse oximetry measurements to ensure their reliability. The findings have significant implications for clinical practice and future research.

The Accuracy of Readily Available Consumer-Grade Oxygen Saturation Monitors in Pediatric Patients

BACKGROUND

Pulse oximetry measurement is ubiquitous in acute health care settings in high-income countries and is familiar to any parent whose child has been treated in such a setting. Oximeters for home use are readily available online and are incorporated in several smartphones and smartwatches.

METHODS

We wished to determine how accurate are oximeters available online that are designated for adult and pediatric use, and the saturation monitor integrated in a smartphone, when used in children, compared to reference, hospital-grade oximeters. We evaluated a fingertip oximeter marketed for children purchased online; an adult fingertip oximeter purchased online; the oximeter integrated in a smartphone; and reference, hospital-grade oximeters. Participants were < 18 y of age. Bland-Altman charts were generated, and the estimated root mean square error (EARMS) was calculated. Rates of failure to obtain a measurement, relationship between device and time to successful measurement, relationship between age and time to successful measurement, and relationship between error (vs the reference device) and age were evaluated for each consumer-grade device.

RESULTS

We measured SpO2 in 74 children between 0.1-17.0 y of age. Subjects weighing < 30 kg had a median (interquartile range [IQR]) age of 2 (1.0 month-1.4 y) months, and subjects weighing ≥ 30 kg had a median (IQR) age of 14.3 (11.9-16.2) y. Readings could not be obtained in 7.5, 0, and 38.8% of subjects using the pediatric, adult, and smartphone oximeters, respectively. The time to successful reading had a modest negative correlation with age with the inexpensive adult and pediatric oximeters. The inexpensive pediatric oximeter had an overall negative bias, with a mean difference from the reference device of -4.5% (SD 7.9%) and an error that ranged from > 8% to < 33% the reference device. The EARMS was 7.92%. The inexpensive adult oximeter demonstrated no obvious trend in error in the limited saturation range evaluated of 87-99%. The overall mean difference was -0.7% (SD 2.5%). EARMS was 2.5%. The smartphone oximeter underestimated SpO2 at saturations < 94% and overestimated SpO2 for saturations > 94%. Saturations could read as much as > 4%, or < 17%, than the reference oximeter. The mean difference was -2.9% (SD 5.2%). EARMS was 5.1%.

CONCLUSIONS

Our findings suggest that the performance of consumer-grade devices varies considerably by both subject age and device. The pediatric fingertip device and smartphone application we tested are poorly suited for use in infants. The adult fingertip device we tested performed quite well in larger children with relatively normal oxygen saturations, and the pediatric fingertip device performed moderately well in subjects > 1 y of age who weighed < 30 kg. Given the vast number of devices available online and ever-changing technology, research to evaluate nonclinical oximeters will continue to be required.

Skin Pigmentation Influence on Pulse Oximetry Accuracy: A Systematic Review and Bibliometric Analysis

Nowadays, pulse oximetry has become the standard in primary and intensive care units, especially as a triage tool during the current COVID-19 pandemic. Hence, a deeper understanding of the measurement errors that can affect precise readings is a key element in clinical decision-making. Several factors may influence the accuracy of pulse oximetry, such as skin color, body temperature, altitude, or patient movement. The skin pigmentation effect on pulse oximetry accuracy has long been studied reporting some contradictory conclusions. Recent studies have shown a positive bias in oxygen saturation measurements in patients with darkly pigmented skin, particularly under low saturation conditions. This review aims to study the literature that assesses the influence of skin pigmentation on the accuracy of these devices. We employed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement to conduct a systematic review retrospectively since February 2022 using WOS, PubMed, and Scopus databases. We found 99 unique references, of which only 41 satisfied the established inclusion criteria. A bibliometric and scientometrics approach was performed to examine the outcomes of an exhaustive survey of the thematic content and trending topics.