Effect of External Positive and Negative Pressure on Venous Flow in an Experimental Model

European Journal of Vascular and Endovascular Surgery : the Official Journal of the European Society for Vascular Surgery
S RajuG Cruse

Abstract

Positive external pressure is said to decrease transmural pressure; negative pressure in the pleural cavity is widely believed to result in negative pressure in systemic chest veins. The discrepancy between erect column height and foot venous pressure has been explained on this basis. These core concepts rest on static closed models that may not be appropriate. This study examined the effects of external pressures in a dynamic open model that may better reflect in vivo conditions. Flow in a Penrose drain enclosed in a chamber that could be positively or negatively pressurized was used. Input and output reservoirs with pressures in the physiological range provided flow. Flow and pressure were monitored in horizontal and erect models with modifications to suit particular experiments. The discrepancy between foot venous pressure and erect venous column height was shown in this experimental model to be a result of two flows in opposite directions (superior and inferior vena cavae) meeting at the zero reference level at the heart; the upper column pressure therefore does not register at the foot. Positive external pressure results in slowing of velocity with conversion to pressure. Internal and transmural pressures therefore do not ...Continue Reading

References

May 1, 1986·Journal of Biomechanical Engineering·Y C Fung, F Y Zhuang
Nov 1, 1972·Cardiovascular Research·P Avasthey
Oct 1, 1969·IEEE Transactions on Bio-medical Engineering·E O Attinger
Oct 1, 1969·IEEE Transactions on Bio-medical Engineering·J P Holt
May 1, 1959·Circulation Research·J P HOLT
Sep 18, 2007·American Journal of Physiology. Heart and Circulatory Physiology·Yi LiuGhassan S Kassab
Jan 1, 2014·Journal of Vascular Surgery. Venous and Lymphatic Disorders·Seshadri RajuJake Olivier

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Citations

Jun 21, 2020·HPB : the Official Journal of the International Hepato Pancreato Biliary Association·Ola AhmedAdeel S Khan
Nov 29, 2020·Journal of Vascular Surgery. Venous and Lymphatic Disorders·Seshadri RajuThomas Powell

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