A water‐pad placed under the plaster may prevent deep venous thrombosis by counteracting venous stasis during periods of lower leg immobilization

‘The venous ejection fraction increased significantly from 30 ± 17% to a maximum of 42 ± 19% during stepping with increasing filling condition (RM anova; P = 0.009).’ During prolonged lower limb immobilization, such as following leg fractures, patients are at risk to develop deep venous thrombosis. This is commonly prevented by the use of heparin to inhibit the coagulation pathway, but several mechanical methods to enhance venous blood flow in the immobilized leg have also been developed. In this issue of Acta Physiologica, Poelkens et al. explore the use of a water-pad, which is placed between the skin and the plaster cast, connecting the sole of the foot with the dorsal side of the calf. It is shown with pletysmography that this device markedly improves the reduced lower leg venous ejection fraction and ejection volume during stepping, with 40% and 41%, respectively. This enlargement represents a substantial reversion of the decreased lower leg venous outflow during leg immobilization. The data support the hypothesis that the water pad mobilizes water, collected at the sole of the foot, to the calf during walking, thereby increasing the pressure around the calf during the stance-phase and assisting the muscle pump to enhance the venous outflow. Future studies are needed to show how well these data obtained during acute immobilization can be generalized to patients undergoing prolonged cast immobilization.