In this study, the level of oxygen within the blood will be reduced in a controlled manner by reducing the concentration of oxygen the study volunteer breathes. The accuracy of a noninvasive pulse oximeter sensor will be assessed by comparison to the oxygen saturation measurements from a laboratory blood gas analyzer.

Inclusion Criteria:

• Competent non-smoking adults between the ages of 18 and 45 for each series of tests.
• Must weigh a minimum of 110 pounds and no more than 250 pounds unless subject is over 6 feet tall.
• Subjects must understand and consent to be in the study.
• American Society of Anesthesiology Class 1 (Healthy subjects without any systemic disease at all).
• Subjects with hemoglobin greater than or equal to 11 g/dL.

Exclusion Criteria:

• Subjects with polished, gel or acrylic nails.
• Subjects with damaged and/or finger nail deformities.
• Subjects who have had caffeine consumption the day of the study.
• Subjects who have taken pain medication 24 hours before the study.
• Subjects who have any systemic disease at all.
• Subjects who do not understand the study and the risks.
• Subjects who smoke.
• Subjects who use recreational drugs.
• Subjects who are pregnant or nursing.
• Subjects having either signs or history of peripheral ischemia.
• Subjects with open wounds, lacerations, inflamed tattoos or piercings, visible healing wounds.
• Subjects with psychiatric conditions or are on psychiatric medications.
• Subjects who have had invasive surgery within the past year- including but not limited to major dental surgery, gallbladder, heart, appendix, major fracture repairs (involving plates/ screws), jaw surgery, Urinary tract surgery, plastic surgery, major ENT surgery, joint replacement or gynological surgeries.
• Subjects who have had minor surgery or conditions in the past two months including but not limited to minor foot surgery (bunion), arthroscopic procedure, blood donation, plasma donation, skin biopsy/ procedures, root canal, fractures, eye surgery, and other minor procedures.
• Subjects that have been on antibiotics had congestion, head colds, flu, ear infection, chest congestion will have a 2 week waiting period from the time of finishing medications or must have no more symptoms.
• Subjects with claustrophobia, or anxiety.
• Subjects who have been in severe car accidents or a similar type of accidents will have a 12 month waiting period, from the time of the accident.
• Subjects who have had a concussion will have a 12 month waiting period, from the time of the concussion.
• Subjects with chronic unresolved asthma, lung disease and respiratory disease.
• Allergies to lidocaine, latex, adhesives, or plastic.
• Subjects with finger deformities or injuries (specific finger will not be used).
• Subjects with heart conditions, diabetes or hypertension.
• Subjects with resting heart rates greater than 85BPM or below 45BPM
• Subjects who have given birth naturally will have 6 month waiting period. Subjects who had a pregnancy terminated, a miscarriage or had a c-section will have a 12 month waiting period.
• Others deemed ineligible by the clinical staff.