Objective: 

To examine the effect of Lower Abdominal Tension (LAT) on blood pressure (BP in mmHg), heart rate (HR) and cardiac baroreflex sensitivity (BRS in ms/mmHg, and BRSf in Hz/mmHg).

Methods: 

We studied seven healthy volunteers of age 30 ± 3 years (mean ± SD). We recorded beat-to-beat arterial blood pressure: systolic (SBP), dyastolic (DBP), mean (MBP); and inter-beat-interval (IBI in ms) with breathing controlled by metronome. Measurments were repeated 3 times (Finapres Ohmeda): First: in supine position. Second: after 20 seconds of a sudden standing from the supine position without abdominal tension. Third: after 20 seconds of a sudden standing with abdominal tension (each measurment lasted 5 minutes). We used spectral analysis to determine BRS and BRSf. The values of the first measurments were taken as base line values.

Results: 

When compared with the base line values, we found that the increase in heart rate during standing with LAT (non-significant=NS) is less than the increase during standing without tension (NS). Increases in systolic, diastolic, and mean blood pressure during standing with LAT were found to be (P=0.031, P=0.018, and P=0.018 consequently), and during standing without tension were (P=0.025, P=0.009 and P=0.011). The baroreflex sensitivity BRS and BRSf non-significantly increased during standing with LAT more than during standing without tension.

Conclusions: 

We found that in orthostatism, increases in HR, baroreflex sensitivity and in the blood pressure during LAT are closely the same as during standing without tension. These results indicate that the use of the LAT alone to avoid orthostatic hypotension is not enough. This study was supported by: MSM0021622402