Physiological basis of the method of negative pressure breathing (NPB) for the correction of postural hemodynamic change

The efficiency of negative pressure breathing (NPB) was investigated in anesthetized cats for correction of hemodynamic changes arising at head-down tilt (HDT-30˚). The pressure rise observed at HDT in v.cava cranialis and v.jugularis externa testifies to the complicated venous outflow from craniocervical vessels. Application of NPB promoted improvement of venous outflow from vascular system of the head that was shown in pressure reduction in jugular vein and precava to the level corresponding to horizontal position of a body. NPB didn't cause significant changes of system hemodynamics and also of breathing pattern and gas exchange. The established facts allow us to make conclusion about the efficiency of NPB to reduce the risk of venous stagnation development in craniocereberal vessels at head-down tilt.