This project aims to test the accuracy of pulse oximeters during mild, moderate, and severe hypoxia, i.e., a range of arterial HbO2 saturation from 100 down to 70%. A typical study will include at least ten subjects (at least 200 necessary data points to meet the ISO 80601-2-61:2017).

After local anesthetic injection, a 22-gauge catheter is inserted in one radial artery. Pulse oximeters are attached to fingers, ears, or flat body surfaces. Subjects are in a comfortable semi-recumbent position. Subjects then breathe air mixtures containing reduced amounts of oxygen to produce the desired level of hypoxemia. Stable, safe, and controlled hypoxia is breath-by-breath by breath respiratory gas analysis and a computer program that permits the inspired gas mixture to be adjusted to achieve a level of lung alveolar gas that will achieve the desired degree of saturation.

Inclusion Criteria:

1. The subject is male or female, aged ≥18 and <50.
2. The subject is in good general health with no evidence of any medical problems.
3. The subject is fluent in both written and spoken English.
4. The subject has provided informed consent and is willing to comply with the study procedures.

Exclusion Criteria:

1. The subject is obese (BMI>30).
2. The subject has a known history of heart disease, lung disease, kidney or liver disease.
3. Diagnosis of asthma, sleep apnea, or use of CPAP.
4. Subject has diabetes.
5. Subject has a clotting disorder.