In this study, the concentration of hemoglobin within the subject's blood will be reduced in a controlled manner by administering fluids intravenously. The accuracy of a noninvasive hemoglobin sensor will be assessed by comparison to hemoglobin measurements from a laboratory analyzer.

Inclusion Criteria:

• Subject weighs a minimum of 110 lbs and no more than 250 lbs unless subject is over 6 feet tall.
• Hemoglobin value is greater than or equal to 11 g/dL at time of screening
• Baseline heart rate ≥ 45 bpm and ≤ 85 bpm.
• CO value ≤ 2.0% FCOHb
• Subject has a physical status of ASA I or II (American Society of Anesthesiology Class I; Healthy subjects without any systemic disease at all. American Society of Anesthesiology Class II; subjects with mild systemic disease) as it applies to the systemic disease portion of the classification.
• Systolic Blood Pressure ≤ 140 mmHg and Diastolic Blood Pressure ≤ 90 mmHg.
• Subject is able to read and communicate in English and understands the study and risks involved.

Exclusion Criteria:

• Subject is pregnant
• Subject smokes (including e-cigarette use)
• Subject has a BMI > 35 and has been classified as morbidly obese or at an increased risk for participation by a medical professional.
• Subject has a history of fainting (vasovagal), blacking out or losing consciousness during or after a blood draw.
• Subject has open wounds, inflamed tattoos or piercings, or any visible healing wounds.
• Subject has known drug or alcohol abuse or uses recreational drugs.
• Subject has experienced a head injury with loss of consciousness within the last year.
• Subject has taken anticoagulant medication within the last 30 days.
• Subject has any chronic bleeding disorders (i.e. hemophilia).
• Subject has any history of a stroke, myocardial infarction, heart attack, or seizures.
• Subject has any cancer or history of cancer (not including skin cancer).
• Subject has a chronic neurological disease (i.e. multiple sclerosis, Huntington's disease).
• Subject has any cardiac dysrhythmias (i.e. atrial fibrillation) and has not received clearance from their physician.
• Subject has known neurological and/or psychiatric disorder (i.e. schizophrenia, bipolar disorder) that interferes with the subject's level of consciousness.
• Subject has Wolff-Parkinson-White Syndrome or Stokes-Adams Syndrome
• Subject has any medical condition which in the judgment of the investigator and/or medical staff, renders them ineligible for participation in this study (Discretion of investigator).
• Subject has taken opioid pain medication within 24 hours of start of study.
• Subject has any type of infectious disease (i.e. Hepatitis, HIV, Tuberculosis, Flu, Malaria, Measles, etc.).
• Subject is taking medications known to treat any type of infectious disease.
• Subject has either signs or history of peripheral ischemia or carpal tunnel.
• Subject has 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 gynecological surgeries, heart surgery or thoracic surgery.
• Subject has symptoms of congestion, head colds, flu, or other illnesses
• Subject has donated blood within the last 2 weeks.
• Subject is claustrophobic or has generalized anxiety disorder.
• Subject has been in severe car accident(s) or a similar type of accident(s) requiring hospitalization within the last 12 months.
• Subject has had a concussion within the last 12 months.
• Subject has chronic unresolved asthma, lung disease or respiratory disease.
• Subject is allergic to lidocaine, latex, adhesives, or plastic.
• Subject has heart conditions, insulin-dependent diabetes or uncontrolled hypertension.
• Subject has delivered vaginally, has had a pregnancy terminated, a miscarriage with hospitalization, or had a C-section within the last 6 months.
• Subject intends on participating in any heavy lifting, repetitive movement of their wrist (including riding a motorcycle) or exercise (working out, riding a bike, riding a skate board etc.), or any activity that will put additional stress on the wrist within 24 hours following a study that involves an arterial line.
• Discretion of investigator/study staff

Subjects whose hemoglobin levels did not meet predefined study requirements were not included in the final data analysis.

5 months