Comparison of Tissue Oxygenation Measurement Using Multimodal Devices

During consenting period, the Modulim equipment will be calibrated and setup ready for scanning. Subject's volar aspect of the thumb along with the palm surface will be ready to target the optical camera head. Actual scanning takes less than 60 seconds. The images will be processed offline. During processing 3-5 different regions of interest will be taken to measure the oxygen parameters such as tissue oxygen saturation, oxy-hemoglobin, deoxy-hemoglobin, superficial hemoglobin, and sub-surface hemoglobin.

Transcutaneous oxygen monitoring (TCOM or TcpO2) is a noninvasive, clinically-approved method to obtain skin oxygen levels. The method is quantitative, and measures oxygen delivery to the skin from underlying tissue. Before positioning the electrode, an adhesive fixation ring will be placed on the dry skin on the volar aspect of the thumb and an electrolyte as a contact liquid will be filled half and the probe is aligned into it by rotating clock-wise to fasten it. Recording will be started and waited for the oxygen level to stabilize and a fixed value will be recorded. The probe will be heated to about 45oC. Although this device has other options, only the measurement of O2 will be performed using this device.

The apple watch is equipped with green, red, and infrared LEDs that shine light onto the blood vessels in the wrist, with photodiodes measuring the amount of light reflected back. Apple's algorithms use this information to calculate the color of the blood, which is an indication of how much oxygen is in the blood. Bright red blood is well oxygenated, while darker blood has less oxygen. This can measure blood oxygen levels between 70 and 100 percent. Most healthy people have blood oxygen levels that range from 95 to 100 percent. The apple watch sensor will be positioned on the user's preferred wrist.

The pulse oximeter enables transcutaneous monitoring of the oxygen saturation of hemoglobin in arterial blood. In this study, volar aspect of thumb and index finder of the subject will be used to measure blood oxygen saturation.