This project aims to test the accuracy of pulse oximeters in the range of arterial HbO2 saturations from 100% down to 70%.

This project aims to test the accuracy of pulse oximeters in the range of arterial HbO2 saturations from 100% down to 70%. This is done by comparing the pulse oximeter reading during brief, steady state hypoxia plateaus with a gold-standard measurement of blood oxyhaemoglobin saturation.

Inclusion Criteria:

• Male or female, aged >= 18 and < 50.
• Subject in good general health with no evidence of any medical problems.
• Subject is fluent in both written and spoken English.
• Subject has provided informed consent and is willing to comply with the study procedures.

Exclusion Criteria:

• Subject is obese (BMI > 35).
• Subject has a known history of heart disease, lung disease, kidney, or liver disease.
• Diagnosis of asthma, sleep apnea, or use of CPAP.
• Subject has diabetes.
• Subject has a clotting disorder.
• Subject has hemoglobinopathy or history of anemia, per subject report or the first blood sample, that in the opinion of the investigator, would make them unsuitable for study participation.
• Subject has any other serious systemic illness.
• Subject is a current smoker.
• Any injury, deformity, or abnormality at the sensor sites that in the opinion of the investigators would interfere with the sensors working correctly.
• Subject has a history of fainting or vasovagal response.
• Subject has a history of sensitivity to local anesthesia.
• Subject has a diagnosis of Raynaud's disease.
• Subject has unacceptable collateral circulation based on exam by the investigator (Allen's test).
• 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 study procedures.
• Subject has any other condition, which in the opinion of the investigators would make them unsuitable for the study.