A non-invasive, painless test measuring oxygen levels in the blood, pulse oximetry is routinely performed during medical exams. It is typically measured in doctor’s offices, emergency rooms, and upon hospital admittance, but has also seen use in a wide range of clinical trials. While self-monitoring for Covid-19 is what put at-home pulse oximetry in the news in the last year, it has additional benefits to patients, healthcare professionals, and medical research: it can be beneficial for remote triaging and may even help patients better determine when they need to seek in-person treatment.
At the start of the Covid-19 pandemic, many members of the public developed an interest in pulse oximetry, as one of the main symptoms of Covid-19 is decreased oxygen levels in the blood. This symptom can be easily detected using a pulse oximeter which can now often be purchased over the counter (OTC). With the knowledge that pulse oximeters were readily available (in lieu of SARS-CoV-2 PCR-based diagnostic testing, which was not), many people purchased pulse oximeters to monitor their blood oxygen levels at home.
Measuring capillary blood oxygen levels with pulse oximetry
In the United States, for manufacturers to receive 510(k) clearance for a pulse oximeter, the FDA specifies that the root-mean-square error must be less than 3%. Some pulse oximeters currently marketed to consumers may not meet this requirement, and/or may not have 510(k) clearance. While fitness trackers and other devices like the Apple Watch can also collect pulse oximetry data, manufacturers have made it clear that data from these devices is not intended for medical decision-making, only recreational use.
Both environmental and physiological conditions can contribute to altered pulse oximetry readings, including conditions like poor blood circulation, cold hands, carbon monoxide poisoning, and others. These factors all must be taken into account when patients are collecting data without the supervision of a medical professional, and patients must also be cognizant of each manufacturers’ recommendations regarding data collection.
The impact of skin color on pulse oximetry data also caught the public’s attention when a New England Journal of Medicine article offered evidence that some pulse oximeters’ readings may not be as accurate for people with darker skin tones. This issue is more apparent when oxygen levels are low, which is most significant in a clinical setting. With many different pulse oximeter models available, continuous and remote monitoring may be plausible; however, the data quality necessitates additional investigation as measurements may differ from one model to another.
The study of pulse oximetry
A recent independent study testing the Nonin Model 3230 pulse oximeter found that the device was accurate for people with varying skin tones, including when low oxygen levels were present as a result of conditions like COPD, respiratory infections, or lung cancer. This indicates that device-dependent issues like skin pigmentation must be adequately tested and documented to ensure that a device is fit for purpose.
The rise in popularity of pulse oximeters as a result of the pandemic is just one example of a remote monitoring technology moving into the home — a transition which changes the context of use, and will have both positive and negative consequences. At the conclusion of the study, a decision tree was proposed to standardize the process of moving remote monitoring technologies such as pulse oximeters from the clinic to a remote setting like a home.
Shifting remote monitoring technologies from an in-clinic setting to a remote setting requires careful planning, data collection, processing, and analysis, as new measures will need to be developed for remote settings. This transition to remote and continuous monitoring is likely to continue long after the Covid-19 pandemic ends, and this new paradigm for patient care and research will continue to improve the accuracy of health data and ensure that treatments are available for patients who need them — wherever they are.
Learn more about Koneksa’s digital biomarker platform, including vital signs monitoring, at koneksahealth.com.
Koneksa is a leading patient-centric digital biomarker company for the pharmaceutical and biotechnology industries that develops end-to-end solutions for remotely collected clinical data. We help produce more meaningful data in clinical research by delivering integrated solutions for efficient trial designs that collect data in real-world settings.