The effects of vibration upon blood-viscosity and red-cell mobility: A study in vivo and in vitro

It has long been established that vibration can produce vasospastic disease with associated hyperviscosity. More recently it has been shown that short-term exposure to vibration may lead to increased blood-flow; the associated blood rheology of this has not been studied. The vibration used in this study was of the three dimensional type known as “cycloid” vibration. It is often used in physiotherapy departments and is therefore of particular interest. Investigations have been carried out to determine the effects on blood-viscosity at shear rates between 230 s⁻¹ and 0.0734 s⁻¹ of whole-body vibration, at a frequency of 50 Hz for 15 minutes in the rabbit and of the effects of in vitro vibration on both human and rabbit blood. Haematocrit, yield stress, erythrocyte electrophoretic mobility and zeta-potential were also estimated. Three studies were carried out:- I. Comparison of blood with and without in vitro vibration from human volunteers with hyperviscosity (N = 5). II. Comparison of blood from lop-eared rabbits before and after whole-body vibration (N = 11). III. Comparison of blood from lop-eared rabbits after in vitro vibration and after whole-body vibration (N = 10). The frequency of vibration was 50 Hz, the amplitude was 0.8 mm and the duration was 15 minutes. It was shown that vibration of either human or rabbit blood in vitro has no effect on blood-viscosity at any shear rate, on red cell mobility, on zeta-potential or on yield stress. Whole-body vibration produced no significant effect on rheology at rates of shear above 2 s⁻¹, but low-shear viscosity (<1 s⁻¹ Shear rate) became more nearly Newtonian after vibration, with a significant reduction in yield stress from 5.71 ± 0.14 mNm⁻² to 3.54 ± 0.32 mNm⁻² (p < 0.005). There were no significant changes in electrophoretic mobility (i.e. zeta-potential).