**Abstract**

The aim of study is finding complex pathological process markers occurred in COVID-19. Adaptive capacity, cardiovascular features, autonomic, central nervous systems in 67 patients with severe COVID-19 were studied and evaluated using (suggested by authors) temporal, spectral, correlation analysis of arterial oscillograms (AOG). The method is based on mathematical analysis adaptation of electrocardiographic signal heart rate variability to arterial pulsation variability analysis recorded during blood pressure measurement using an electronic tonometer VAT 41–2. Received results were compared with AOG 480 healthy (including 68 people after exercising) and 26 patients in a closed ward at psychoneurological hospital. Study results showed patients with severe COVID-19 have disorders at (four) cardiovascular system (CVS) regulation levels. It's confirmed by lack of adequate sympathetic-adrenal response to a stressful situation due to severe COVID-19; higher than in healthy, parasympathetic part activity of autonomic nervous system. AOG spectral analysis revealed violation of management centralization, communication and coordination between CVS regulation levels. This leads to functional reserves decrease, low stress resistance of body and finally to a disease severe course and recovery processes. Arterial oscillography can be used to search markers of complex pathological processes occurred in COVID-19 and to improve methods of diagnosis, treatment, control of long-term results in clinical and family medicine.

**Keywords:** Arterial oscilography, adaptive capacity of the body, heart rate variability, COVID-19, primary care
