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This Article Full Text Full Text (PDF) All Versions of this Article: 105/3/811    most recent 90304.2008v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Groothuis, J. T. Articles by Hopman, M. T. E. PubMed PubMed Citation Articles by Groothuis, J. T. Articles by Hopman, M. T. E.

Leg intravenous pressure during head-up tilt

Departments of ¹Physiology, ²Internal Medicine, ³Pharmacology-Toxicology, and ⁴Cardiology, Radboud University Nijmegen Medical Centre; and ⁵Department of Rehabilitation Medicine, Sint Maartenskliniek, Nijmegen, The Netherlands

Submitted 21 February 2008 ; accepted in final form 10 July 2008

Leg vascular resistance is calculated as the arterial-venous pressure gradient divided by blood flow. During orthostatic challenges it is assumed that the hydrostatic pressure contributes equally to leg arterial, as well as to leg venous pressure. Because of venous valves, one may question whether, during orthostatic challenges, a continuous hydrostatic column is formed and if leg venous pressure is equal to the hydrostatic pressure. The purpose of this study was, therefore, to measure intravenous pressure in the great saphenous vein of 12 healthy individuals during 30° and 70° head-up tilt and compare this with the calculated hydrostatic pressure. The height difference between the heart and the right medial malleolus level represented the hydrostatic column. The results demonstrate that there were no differences between the measured intravenous pressure and the calculated hydrostatic pressure during 30° (47.2 ± 1.0 and 46.9 ± 1.5 mmHg, respectively) and 70° head-up tilt (83.9 ± 0.9 and 85.1 ± 1.2 mmHg, respectively). Steady-state levels of intravenous pressure were reached after 95 ± 12 s during 30° and 161 ± 15 s during 70° head-up tilt. In conclusion, the measured leg venous pressure is similar to the calculated hydrostatic pressure during orthostatic challenges. Therefore, the assumption that hydrostatic pressure contributes equally to leg arterial as well as to leg venous pressure during orthostatic challenges can be made.

venous pressure; hydrostatic pressure; leg vascular resistance