BAROREFLEX SENSITIVITY DURING PSYCHOLOGICAL STRESS

The aim of this study was to analyse the changes of baroreflex sensiti vity (BRS) and their relation to changes of heart rate and blood press ure in medical students during moderate psychological stress brought a bout by oral examination. The changes of BRS during the stress were co mpared with the changes during light physical exercise. Thirty three s tudents were examined 30 min before and 30 min after the exam. Thirty- nine students of control group were examined at rest and during light exercise. Blood pressure was noninvasively recorded by Penaz method at rate-controlled breathing (0.33 Hz). The BRS [ms/mm Hg] and BRS(f) [H z/mm Hg] were calculated by spectral analysis of spontaneous fluctuati ons of blood pressure and inter-beat intervals (IBI). BRS before exami nation (7.12 ms/mm Hg) was significantly lower than after the oral exa m (8.77 ms/mm Hg, p < 0.05). The difference between BRS in the test gr oup after the oral exam and the control group at rest (10.78 ms/mm Hg) was not significant. BRS during light exercise (7.44 ms/mm Hg) corres ponded to the value during psychological stress. The values of BRS(f) did not change during psychological stress (before: 0.0182 Hz/mm Hg; a fter: 0.0182 Hz/mm Hg) and exercise (rest: 0.0158 Hz/mm Hg; exercise: 0.0144 Hz/mm Hg). Correlation between BRS or BRS(f) and blood pressure were not found. A significant negative correlation (r = -0.404, p < 0 .05) between BRS(f) and the increase of diastolic blood pressure durin g stress was observed. It is concluded that BRS(f) remained constant d uring psychological stress and exercise, and differed essentially from that in hypertensive subjects.