Document Detail


Microvascular fluid filtration capacity (Kf) assessed with cumulative small venous pressure steps and with various degrees of tilt.
MedLine Citation:
PMID:  10425263     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
METHOD: The study, which was approved by the local ethical committee of the Institute of Biomedical Problems, was performed on six healthy 20 - 26 years old male volunteers. We applied 6 - 8 cumulative small venous congestion pressure steps (8 mmHg) to the thigh and determined the fluid filtration capacity (Kf), the linear relationship between cuff pressure (Pcuff) and measured fluid filtration (Jv). We then measured the fluid filtration (Jv) response to varying cumulative degrees of tilt, starting at 0 degrees followed by head down -8 degrees -15 degrees, -30 degrees -15 degrees, -8 degrees, 0 degrees, and then head up 15 degrees, 30 degrees, 70 degrees, 30 degrees, 15 degrees and 0 degrees. Each tilt stage was sustained for 15 minutes. The change in hydrostatic load, at the level of the strain gauge, was determined by measuring the difference in vertical height between the right atrium and mid calf at the level of the gauge. Limb arterial blood flow was measured and lung function tests were performed before and after the small cumulative pressure step protocol, as well as at the end of each tilt step.
RESULTS: No significant changes in blood pressure (BP) and heart rate (HR) occurred during the cumulative pressure step protocol. However, an increase in HR was observed during the tilt, but only reached significance at 30 degrees and 70 degrees. The mean Kf value measured with small cumulative pressure steps was 3.25 +/- 0.5 (10(-3) ml.100 ml tissue(-1) mmHg(-1) = KfU), which was significantly (p < 0.005) higher than the value obtained using tilt to increase the hydrostatic load (0.98 +/- 0.2 KfU). One subject had an unchanged Kf value and experienced vaso - vagal syncope following the imposition of 70 degrees tilt, with a heart rate < 35 / min and a systolic blood pressure of 60 mmHg. The measurement of blood flow in the limb showed no significant change during the tilt procedure. The lung function measurements revealed, that only expiratory reserve volume (ERV) did significantly increase during 35 degrees and 70 degrees head up tilt. All other parameters were unchanged. We suggest that the differences in these Kf values can be explained by the activation of both central and peripheral mediated changes in pre- capillary resistance in response to the tilt. We suspect, that the vaso - vagal syncope, experienced by one subject, reflected his inability to activate these protective reflex mechanisms, a situation that could be exacerbated by sub-clinical venous insufficiency. We believe that these results show that VCP is a useful tool for the determination of intolerance to orthostatic stress.
Authors:
F Christ; J Gamble; V Baranov; A Kotov; I Gartside; I Nehring; K Messmer
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of medical research     Volume:  4     ISSN:  0949-2321     ISO Abbreviation:  Eur. J. Med. Res.     Publication Date:  1999 Jul 
Date Detail:
Created Date:  1999-10-14     Completed Date:  1999-10-14     Revised Date:  2013-05-20    
Medline Journal Info:
Nlm Unique ID:  9517857     Medline TA:  Eur J Med Res     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  264-70     Citation Subset:  IM; S    
Affiliation:
Institute of Anaesthesiology, Ludwig Maximilians University Munich, D-81366 Munich, Germany. frank.christ@ana.med.uni-muenchen.de
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MeSH Terms
Descriptor/Qualifier:
Adult
Blood Pressure*
Humans
Male
Posture*
Regional Blood Flow
Respiratory Function Tests
Stress, Physiological / physiopathology*
Veins / physiopathology*

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