The Accuracy of Smartphone Pulse Oximetry in Patients Visiting an Outpatient Pulmonary Function Lab for a 6-Minute Walk Test

Inclusion Criteria: * Ambulatory * 18 years and older * Visiting the pulmonary function laboratory at Rush University Medical Center for a 6-minute walk test that agree to participate. Exclusion Criteria: * Under the age of 18 years * High blood pressure above 180/90 mm Hg or pressure below 70/50 mm Hg * Dizzy, lightheaded or have severe headaches at time of enrollment * SpO2 at or below 85% on supplemental oxygen * On oxygen greater than 4 liters per minute * Gait issues that may result in a fall or patient walks with a walker and did not bring the device to this visit