ON VARIATIONS OF HUMAN HEMODYNAMIC PARAMETERS CAUSED BY NEGATIVE PRESSURE BREATHING DURING 15-HOUR HEAD-DOWN TILT

The cardiovascular reaction to negative pressure breathing (NPB) was studied in human subjects in the condition of 15-hour head-down tilt (-15°). Amplitude and time characteristics of tidal oscillations of physiological parameters synchronous to free and NPB breathing were measured after 14 hours in HDT. Oscillations of cardiovascular parameters were determined using the coherent averaging technique. A multiple increase in amplitude was stated during transition from free breathing to NPB, whereas variations of the other characteristics of oscillations were little affected.

Stress reactivity in patients with workplace hypertension

Aim. To investigate the specific features of stress reactivity and diagnostic potential of psycho-emotional tests for identification of the patients with workplace arterial hypertension (WPAH). Material ad methods. The study included 197 patients with WPAH and 132 subjects with essential AH (EAH). All participants underwent blood pressure monitoring (BPM) during work and leisure hours and stress reactivity assessment (count test). Results. In WPAH and EAH patients, the count test resulted in increased systolic (SBP), diastolic (DBP) BP, and heart rate (HR) (р<0,001), which was an evidence of stress-related functional cardiovascular reaction. In subjects with new-onset WPAH, compared to EAH patients, the SBP and HR increases were greater by 7,9 mm Hg (р<0,005) and 4,3 bpm (р<0,001), respectively. In patients with long-term EAH, SBP increase was greater by 3,4 mm Hg (p=0,03), with a halved HR increase (p<0,001). In healthy controls and AH patients, the differences between baseline levels of SBP and DBP, peak levels during the count test, and BMP levels for work hours were comparable. Conclusion. The patients at early WPAH stages were characterized by increased cardiovascular reaction to acute induced psycho-emotional stress. At the later WPAH stages, BP reactivity was reduced. The cont test could be used as a screening tool in patients with undiagnosed WPAH.