Vital sign monitoring - from home over antarctica to space

Monitoring of autonomous nervous system (ANS) activity in extreme environments remains a fundamental challenge. We propose a new four-dimensional approach to monitor autonomic nervous system status. HRV parameters constitute the first dimension, but will be supplemented by photoplethysmographic (PPG) measurements of the rhythmical variations of skin blood content as the second, and recordings of skin conductance responses (SCR) as the third dimension. The respiratory rhythm (RR) is recorded as the fourth dimension. By employing mathematical algorithms sensitive to transitions (e.g. wavelet transform) to the rhythms in these four dimensions (HRV-PPG-SCR-RR), different operational modes of the ANS can be distinguished. We present such patterns of ANS activity during relaxation and in response to changes of body position (supine, head-up and head down tilt), mental workload, and emotional arousal.