The goal of this study was to evaluate the accuracy of pulse oximeters over the range of 70-100% per ISO 80601-2-61:2019. Four devices were placed on each subject with two on each index finger at the base and two on each index finger at the fingertip. SpO2 measurements from these devices were compared to sampling of arterial blood during brief stable oxygen desaturation in healthy volunteers to evaluate the claimed range.

The study is an open enrollment, single-center, single blinded design using the investigational ring compared to arterial blood gas measurements (SaO2) and to two commercially available hospital grade reference pulse oximeters (Massimo Radical-7 and Nellcor N-595). To be included in the study, subjects had to meet all the inclusion criteria and not meet any of the exclusion criteria and to sign the written consent. Demographic data were obtained.

The investigational (4/subject) and reference devices were placed. A radial arterial cannula was placed in either the left or right wrist of each subject for arterial blood sampling and blood pressure monitoring. Each subject had two control blood samples taken at the beginning of each experiment, while breathing room air. Hands with test devices and reference pulse oximeters were maintained motionless on arm boards throughout the test. Hypoxemia was then induced to different and stable levels of oxyhemoglobin saturation (between 70-100%) by having subjects breathe mixtures of nitrogen, air, and carbon dioxide. The mixture of gases was controlled by the study physician by adjusting gas flows according to breath-by-breath estimates of oxygen saturation calculated from end-tidal partial pressure of oxygen (PO2) and partial pressure of carbon dioxide (PCO2). Each plateau level of oxyhemoglobin saturation was maintained for at least 30 seconds or until readings were stable. Two arterial blood samples were then obtained, approximately 30 seconds apart. Each stable plateau was maintained for at least 60 seconds with SpO2 fluctuating by less than 2-3%. All investigational, control, and reference data were recorded.

Inclusion Criteria:

Subject is in good general health with no evidence of any medical problems. Subject is fluent in both written and spoken English. Subject provided written informed consent and is willing to comply with the study procedures.

Subject is willing to have their skin color assessed.

Exclusion Criteria:

Subject is obese with a BMI over 30. Subject has a known history of heart disease, lung disease, kidney or liver disease.

Subject has asthma, sleep apnea, or uses a CPAP. Subject has diabetes. Subject has a clotting disorder, anemia, or in the opinion of the investigator, they would be unsuitable for participation.

Subject has any other serious system illness. Subject is a current smoker. Subject has any injury, deformity, or abnormality at the sensor sites that, in the opinion of the investigator, would interfere with the sensors working correctly.

Subject has a history of fainting or vasovagal response. Subject has a sensitivity to local anesthesia. Subject has Raynaud's disease. Subject has unacceptable collateral circulation based on an exam by the investigator.

Subject is pregnant, lactating, or trying to get pregnant. Subject is unable or unwilling to provide informed consent or is unable or unwilling to comply with the study procedures.

Subject has any other condition, which in the opinion of the investigator, would make them unsuitable for the study.

Healthy adult participants 18 to 49 years old, of which 2 or 15% of the subject pool is darkly pigmented.