Investigation of pulse oximeter failure rates during artificial hypoperfusion utilising a custom made multimode pulse oximetery sensor

Pulse oximetry utilises the technique of photople-thysmography (PPG) to estimate arterial oxygen saturation values (SpO2). In poorly perfused tissues, SpO2 readings may be compromised due to the poor quality of the PPG signals. In order to investigate further the threshold where pulse oximetry fails to produce accurate SpO2 values, we have developed a custom made multimode finger pulse oximetry probe that operates in conventional, reflectance and transmittance mode independently and also in a combined mode called transreflectance. Experiments on twenty healthy volunteers undergoing induced artificial hypoperfusion utilising a brachial blood pressure cuff were performed in order to investigate the possible threshold of failure to accurately estimate SpO2 values from all pulse oximetry modes. The results suggest that the transreflectance pulse oximeter endures more in estimating accurately SpO2 values when compared with the other two custom made pulse oximeters and a commercial finger pulse oximeter.