Prizma Pulse Oximeter Evaluation

The device under test was the Prizma which is a phone cover biometric device that includes reflectance oximetry. This device is a spot checker that requires the patient to hold their finger on the sensor during the measurement. The subjects were asked not to move during the study. In order to get consistent measurements the fingers were taped to the test device. The tape acted mainly as a reminder, and there were some problems with finger movement. A radial arterial cannula was placed in either the left or right wrist of each subject.

Blood gas analysis to determine oxyhemoglobin saturation was performed on an OSM-3® multi-wavelength oximeter (Hemoximeter, Radiometer, Copenhagen). No subject was anemic (Hemoglobin ≤ 10gm•dl-1). Each subject had control data taken at the beginning of each experiment, with two control blood samples drawn while breathing room air. Hypoxia was induced to different levels of oxyhemoglobin saturation (between 70-100%) by having subjects breathe mixtures of nitrogen, room air, and carbon dioxide. Oxyhemoglobin saturation was reduced to a series of targets and stabilized at the plateau value. Each plateau level of oxyhemoglobin saturation was maintained for at least 30 seconds. Two arterial blood samples were then obtained, approximately 30 seconds apart. A total of 24 samples were obtained per subject. Data were recorded by Bickler-Ye lab and provided for analysis.