Detection of sympathoadrenal discharge by parameterisation of skin conductance and ECG measurement

Detection of sympathoadrenal discharge is valuable for stress monitoring, but measuring the circulating adrenaline level directly is inconvenient, making non-invasive physiological sensors an attractive alternative. Little is known however, about their performance in detecting different adrenaline levels. In this study, adrenaline measurements over time from 20 subjects × 2 trials were compared with skin conductance (SC) from different skin sites and ECG recordings from which the heart rate and QT interval were derived. The frequency of sudomotor responses (FSR) was derived from the SC recording, and a new composite parameter for amplification of synchronous changes in multiple sensor signals was calculated for different combinations of FSR from different skin sites, heart rate and QT interval. The single and composite parameters were evaluated for detection performance of adrenaline levels above 1000, 1500 and 2000 pmol/L. The best prediction performance was indicated for the composite parameter using the FSR from the abdomen, FSR from the forehead and the heart rate, with a ROC area under the curve of 0.93 for the 2000 pmol/L threshold. In conclusion, detection of strong sympathoadrenal discharges is feasible with good accuracy during resting conditions in comfortable room temperature.