Low perfusion testing
submersion, desaturation
In the low perfusion group, the multiple step desaturation method was used to collect the data pairs in SpOEach subject’s left arm was submerged in an ice bath while the right arm was kept warm to serve as a control. In this group of healthy volunteers there were no expected baseline perfusion differences between the right and left arm, so the left arm was used in all subjects for consistency of experimental setup. Due to the time required to develop low perfusion in the experimental arm and the time that would have been required to recover that extremity to normal perfusion and immerse the opposite arm, rotation of the test and control arms was not feasible. The length of submersion was determined by the Perfusion Index (PI) as measured by the GE SpOPulse oximetry measurements were recorded continuously at each saturation plateau and SpO