Duplex scanning to evaluate the effect of compression on venous reflux

AIM

The aim of this study was to demonstrate the usefulness of Duplex in measuring venous reflux and changes in reflux caused by leg compression.

METHODS

Twelve patients with severe incompetence of the great saphenous vein (GSV) were investigated. A special Duplex probe was fixed by tapes on the mid-thigh portion of the incompetent GSV and reflux elicited by tip toeing was measured. Elastic and inelastic compression material with an interface supine pressure around 20, 40 and 60 mmHg was applied on the lower leg and the reflux measurement was repeated.

RESULTS

Increasing compression of the leg led to a progressive reduction of the reflux in the GSV. Ultimately reflux was completely abolished by inelastic compression with a median pressure of 86 mm Hg in the standing position. Elastic material exerting this pressure can achieve similar results but is not tolerated by patients.

CONCLUSION

Duplex is able to demonstrate a reduction of GSV reflux caused by compression of the lower leg, which explains one major beneficial effect of compression on the disturbed haemodynamics in venous incompetence.

Comparison of three portable instruments to measure compression pressure

AIM

Measurement of interface pressure between the skin and a compression device has gained practical importance not only for characterizing the efficacy of different compression products in physiological and clinical studies but also for the training of medical staff.

METHODS

A newly developed portable pneumatic pressure transducer (Picopress®) was compared with two established systems (Kikuhime® and SIGaT tester®) measuring linearity, variability and accuracy on a cylindrical model using a stepwise inflated sphygmomanometer as the reference. In addition the variation coefficients were measured by applying the transducers repeatedly under a blood pressure cuff on the distal lower leg of a healthy human subject with stepwise inflation.

RESULTS

In the pressure range between 10 and 80 mmHg all three devices showed a linear association compared with the sphygmomanometer values (Pearson r>0.99). The best reproducibility (variation coefficients between 1.05-7.4%) and the highest degree of accuracy demonstrated by Bland-Altman plots was achieved with the Picopress® transducer. Repeated measurements of pressure in a human leg revealed average variation coefficients for the three devices of 4.17% (Kikuhime®), 8.52% (SIGaT®) and 2.79% (Picopress®).

CONCLUSION

The results suggest that the Picopress® transducer, which also allows dynamic pressure tracing in connection with a software program and which may be left under a bandage for several days, is a reliable instrument for measuring the pressure under a compression device.

Is low compression pressure able to improve venous pumping function in patients with venous insufficiency?

Background

A too high resting pressure of compression devices is poorly tolerated and may cause skin defects, especially in patients with concomitant arterial occlusive disease.

Aim

To investigate whether low compression pressure will improve venous pumping function in patients with venous incompetence.

Material and methods

Venous pumping function was assessed in 20 patients with severe reflux in the great saphenous vein by measuring ejection fraction (EF) using strain-gauge plethysmography. Measurements were repeated after application of knee-high medical compression stockings and of inelastic bandages applied with a pressure of 20, 40 and 60 mmHg in the supine position.

Results

EF was significantly reduced compared with healthy controls. Compression stockings exerting a median pressure of 27 mmHg (interquartile range [IQR] 25–29) in the supine and 30.5 mmHg (IQR 28.25–34.25) in the standing position produced a moderate, non-significant improvement of EF of 17%. Inelastic bandages with a resting pressure of 20.5 mmHg (IQR 20–22) in the supine position resulting in a standing pressure of 36 mmHg (IQR 33–40.75) led to a significant increase of EF of 61.5% ( P < 0.01). A further increase of the resting pressure to 40 and 60 mmHg achieved an increase of the EF of 91% and 98%, respectively ( P < 0.001).

Conclusions

In patients with venous pumping failure, inelastic bandages produce a significant pressure-dependent increase of EF. A significant improvement in venous pumping function was achieved with inelastic bandages even at a resting pressure of 20 mmHg.

Thigh compression after great saphenous surgery is more effective with high pressure

AIM

Methods to compress thigh veins effectively after venous surgery or endovenous procedures are still disputed. The aim of this paper was to compare the clinical outcomes with three different compression devices as a function of the pressures exerted.

METHODS

Fifty-four patients undergoing invagination stripping of the great saphenous vein and side branch evulsion under local anaesthesia were treated postoperatively in sequential order by 1) thigh length compression stockings; 2) adhesive bandages; and 3) newly developed eccentric compression pads fixed with tapes and a thigh length stocking on top. Sub-bandage pressures were measured at mid-thigh level under these devices after application and one week later before compression was removed. Pain, hematoma, bleeding through the bandage, discomfort and skin irritations were recorded and rated as major or minor adverse events.

RESULTS

The lowest sub-bandage pressure of around 15 mmHg at thigh level in the lying position were found in group A under the compression stockings, which nominally provide 23-32 mmHg at ankle level. Group B and group C showed significantly higher values (median values of 47 and 68 mmHg respectively in lying position, P<0.001). The median pressure values in the three groups upon standing were 16 mmHg, 63 mmHg and 98 mmHg. One week later there was a pressure-drop in the lying position in the three groups of 13%, 64%, and 46% respectively. Major adverse events were seen in a total of 10 of 18 patients in group A, in 1/18 in group B, and in 0/18 in group C. Minor adverse events in the three groups consisting mainly of light discomfort for compression devices and local skin irritations were observed in 6, 6 and 15 cases respectively.

CONCLUSIONS

The best results with respect to the reduction of pain and hematoma were obtained when eccentric compression pads were taped to the skin of the thigh and a compression stocking was worn on top. A possible explanation for these observations is the very high local pressures under the eccentric device.

Definition of post-thrombotic syndrome of the leg for use in clinical investigations: a recommendation for standardization

SUMMARY

The post-thrombotic syndrome (PTS) is increasingly recognized to be a common and important complication of deep venous thrombosis (DVT). Because there is no 'gold standard' objective test to establish its presence, PTS is diagnosed primarily on the basis of the presence of typical symptoms and clinical signs in a limb that was affected by DVT. As a wide variety of definitions of PTS have been used by researchers, it is difficult to compare data across studies and to formally combine data in meta-analyses. In a step towards standardization of the measurement of PTS in clinical studies, available scales and evidence to support their utility to diagnose PTS and to classify its severity were reviewed and discussed at the Control of Anticoagulation Subcommittee of the International Society on Thrombosis and Haemostasis (Vienna, July 2008).

Traveller's thrombosis: international consensus statement

In 2001, consensus meetings on traveller's thrombosis were held in Vienna and Berlin. The results of these conferences were subsequently published in VASA 2002. In 2006 a follow-up conference was organized in Hall, Tirol, Austria, in order to review new and emerging data and to update the conclusions and recommendations of the 2001 meetings. Prior to the conference key papers from peer-reviewed journals were pre-circulated to all participants. The consensus group discussed the data and drafted an updated statement. Thereafter, the writing group summarised the results including the pre-circulated material and additional papers identified by a formal literature search up to December 2007. In this article current knowledge on the incidence, pathophysiology and prevention of traveller's thrombosis is summarised. The assessment of individual risk is described and recommendations for prevention of traveller's thrombosis are given, based upon the conclusions of the Hall Conference.

Thigh compression

The aim of this overview is to discuss the role of thigh compression for the management of venous and lymphatic diseases. The most important indications for thigh compression are prevention and treatment of sequelae of superficial vein procedures (surgery or endovenous procedures), prevention and therapy of deep vein thrombosis (DVT), post-thrombotic syndrome and lymphoedema. The intended effects depend mainly on narrowing/occlusion of deep and superficial veins on which the body position and the applied pressure play a crucial role. While in the horizontal position thigh veins can be narrowed by the light pressure of a thromboprophylactic stocking, much higher pressure is needed to compress thigh veins effectively during standing and walking. This is shown by magnetic resonance imaging (MRI) performed in the supine and upright position. Using pads, rolls or specially designed devices, the local pressure under conventional compression garments or bandages over a treated vein can be increased considerably. In patients with deep valve incompetence, beneficial haemodynamic effects of strong thigh compression have been demonstrated, but clinical studies in this field are still lacking. Thigh compression reduces oedema in patients with DVT and lymphoedema.

Inelastic compression increases venous ejection fraction more than elastic bandages in patients with superficial venous reflux

Aim

To investigate the influence of compression bandages, manufactured using materials with different elastic properties, on the impaired venous pumping function in patients with venous insufficiency.

Methods

Ejection volume (EV) and ejection fraction (EF) were measured using strain gauge plethysmography distal from the patella without and with elastic and inelastic compression bandages in a total of 30 patients with major venous reflux in the great saphenous vein. The interface pressure of the bandages was measured simultaneously in the medial gaiter area. Normal values of EV and EF were obtained from 15 healthy controls.

Results

Patients with venous insufficiency showed a statistically significant reduction of EV and EF compared to controls. Elastic bandages with an average pressure of 42 mm Hg in the supine position achieved a moderate increase of EV and a significant improvement of EF (p < .01), while inelastic bandages applied with comparable resting pressure (41 mm Hg) raised EV and EF into a normal range (p < .001). The improvement of the ejection fraction correlates well with the pressure differences between standing and lying (Static Stiffness Index) and between muscle systole and diastole during exercise (Pearson r = 0.69 and 0.74 respectively, p < .001). Elastic bandages applied with high stretch in order to achieve standing pressures comparable to those of inelastic bandages (>60 mm Hg) led only to a minor improvement of the venous pumping function.

Conclusions

Ejected volume and ejection fraction, which are severely reduced in venous insufficiency, can be increased by compression therapy. Inelastic compression is much more effective than elastic bandages, and is able to normalize venous pumping function. With elastic bandages EV and EF always remain below the normal range even when applied with high stretch producing a resting pressure that is barely tolerable.

Indications for compression therapy in venous and lymphatic disease consensus based on experimental data and scientific evidence. Under the auspices of the IUP

AIM

The aim of this study was to review published literature concerning the use of compression treatments in the management of venous and lymphatic diseases and establish where reliable evidence exists to justify the use of medical compression and where further research is required to address areas of uncertainty.

METHODS

The authors searched medical literature databases and reviewed their own collections of papers, monographs and books for papers providing information about the effects of compression and randomized clinical trials of compression devices. Papers were classified in accordance with the recommendations of the GRADE group to categorize their scientific reliability. Further classification was made according to the particular clinical problem that was addressed in the papers. The review included papers on compression stockings, bandages and intermittent pneumatic compression devices.

RESULTS

The International Compression Club met once in Vienna and corresponded by email in order to reach an agreement of how the data should be interpreted. A wide range of compression levels was reported to be effective. Low levels of compression 10-30 mmHg applied by stockings are effective in the management of telangiectases after sclerotherapy, varicose veins in pregnancy, the prevention of edema and deep vein thrombosis (DVT). High levels of compression produced by bandaging and strong compression stockings (30-40 mmHg) are effective at healing leg ulcers and preventing progression of post-thrombotic syndrome as well as in the management of lymphedema. In some areas no reliable evidence was available to permit recommendations of level of compression or duration of treatment. These included: management of varicose veins to prevent progression, following surgical treatment or sclerotherapy for varicose veins, and the level of compression required to treat acute DVT.

CONCLUSION

This review shows that whilst good evidence for the use of compression is available in some clinical indications, there is much still to be discovered. Little is know about dosimetry in compression, for how long and at what level compression should be applied. The differing effects of elastic and short-stretch compression are also little understood.

Venous reflux surgery promotes venous leg ulcer healing despite reduced ankle brachial pressure index

AIM

The aim of this study was to demonstrate that venous surgery promotes ulcer healing, even in the presence of peripheral arterial disease.

METHODS

In this retrospective study, 33 patients (49 legs) with venous leg ulcers and reduced arterial ankle brachial pressure index (< or = 0.8) were followed up 3 months to 7 years (median: 3.11 years) after venous surgery (group I). Venous reflux was considered to be the main cause of ulceration, and no attempt was made to restore the arterial circulation. The results were compared with those of patients with ulcers without arterial occlusive disease (n=190) who were treated following the same principles (group II). The surgical procedure consisted of interruption of reflux in the superficial and/or perforating veins. Additionally, shaving, fasciectomy, and mesh grafting was performed in 36 cases.

RESULTS

In group I, 21 legs were lost to follow-up, 16 due to death. The mortality rate was three times higher in group I than in group II. From 28 legs of group I seen after 0.4-6.7 years (median: 2.9 years), 19/28 legs (68%) were healed compared with 123/145 (85%) in group II after 0.2-7.2 years (median: 3.2 years) (not significant [NS]). Group I showed a significantly longer healing time than group II (P<0.05) (P<0.001). Recurrence was observed in 3/28 (11%) from group I and in 6/145 (4%) from group II (NS). The time course of recurrence showed no statistically significant difference between the groups.

CONCLUSION

Venous surgery produces beneficial results not only in pure venous ulcerations, but also in patients with accompanying arterial disease.

Guidelines for clinical studies with compression devices in patients with venous disorders of the lower limb

OBJECTIVES

The scientific quality of published clinical trials is generally poor in studies where compression devices have been assessed in the management of venous disease. The authors' aim was to establish a set of guidelines which could be used in the design of future clinical trials of compression treatments for venous diseases.

DESIGN

Consensus conference leading to a consensus statement.

METHODS

The authors form a expert consensus group known as the International Compression Club (ICC). This group obtained published medical literature in the field of compression treatment in venous disease by searching medical literature databases. The literature was studied by the group which attended a consensus meeting. A draft document was circulated to ICC members and revised until agreement between contributors was reached.

RESULTS

The authors have prepared a set of guidelines which should be given consideration when conducting studies to assess the efficacy of compression in venous disease.

CONCLUSIONS

The form of compression therapy including the comparators used in the clinical study must be clearly characterised. In future studies the characteristics of the material provided by the manufacturer should be described including in vivo data on pressure and stiffness of the final compression system. The pressure exerted on the distal lower leg should be stated in mmHg and the method of pressure determination must be quoted.

Compression stockings for treating venous leg ulcers: measurement of interface pressure under a new ulcer kit

Objectives

The aim of this study was to measure the interface pressure of a newly designed two-layer compression stocking (Mediven ulcer kit® Medi QMBH, Bayreuth, Germany) in different body positions and to compare the values with those obtained with another two-layer product.

Methods

Interface pressure was measured on the distal medial leg in 16 legs of volunteers, with the basic layer alone and with the whole stocking kit in the supine, sitting and standing position for both stocking systems. The literature concerning ulcer-healing rates is reviewed.

Results

Mediven ulcerkit® produced statistically significant higher pressure values than the ulcer stocking with a median resting value of 35.5 mmHg in the supine and 42.5 mmHg in the standing position. The pressure while standing comes close to values exerted by bandages. The basic layer alone applies a pressure of 20.5 mmHg.

Conclusions

Especially designed compression stockings exerting sufficient interface pressure may be indicated in patients with small ulcers of short duration.

Duplex ultrasound investigation of the veins in chronic venous disease of the lower limbs-UIP consensus document. Part I. Basic principles

Background: Duplex ultrasound investigation has become the reference standard in assessing the morphology and haemodynamics of the lower limb veins. The project described in this paper was an initiative of the Union Internationale de Phlébologie (UIP). The aim was to obtain a consensus of international experts on the methodology to be used for assessment of veins in the lower limb by ultrasound imaging. Methods: The authors invited a group of experts from a wide range of countries to participate in this project. Electronic submissions from the experts were made available to all participants via the UIP website. The authors prepared a draft document for discussion at an UIP Chapter meeting held in San Diego, USA in August 2003. Following this meeting a revised manuscript was circulated to all participants and further comments were received by the authors and included in subsequent versions of the manuscript. Eventually all participants agreed the final version of the paper. Results: The experts have made detailed recommendations concerning the methods to be used for duplex ultrasound examination as well as the interpretation of images and measurements obtained. This document suggests a methodology for complete assessment of the superficial and perforating veins of the lower limbs, including recommendations on reporting results and training of personnel involved in these investigations. Conclusions: The authors and a large group of experts have agreed a methodology for the investigation of the lower limbs venous system by duplex ultrasonography.

Duplex ultrasound investigation of the veins in chronic venous disease of the lower limbs-UIP consensus document. Part II. Anatomy

Background: Duplex ultrasound investigation has become the reference standard in assessing the morphology and haemodynamics of the lower limb veins. The project described in this paper was an initiative of the Union Internationale de Phlébologie (UIP). The aim was to obtain a consensus of international experts on the methodology to be used for assessment of anatomy of superficial and perforating veins in the lower limb by ultrasound imaging. Methods: The authors performed a systematic review of the published literature on duplex anatomy of the superficial and perforating veins of the lower limbs; afterwards they invited a group of experts from a wide range of countries to participate in this project. Electronic submissions from the authors and the experts (text and images) were made available to all participants via the UIP website. The authors prepared a draft document for discussion at the UIP Chapter meeting held in San Diego, USA in August 2003. Following this meeting a revised manuscript was circulated to all participants and further comments were received by the authors and included in subsequent versions of the manuscript. Eventually, all participants agreed the final version of the paper. Results: The experts have made detailed recommendations concerning the methods to be used for duplex ultrasound examination as well as the interpretation of images and measurements obtained. This document provides a detailed methodology for complete ultrasound assessment of the anatomy of the superficial and perforating veins in the lower limbs. Conclusions: The authors and a large group of experts have agreed a methodology for the investigation of the lower limbs venous system by duplex ultrasonography, with specific reference to the anatomy of the main superficial veins and perforators of the lower limbs in healthy and varicose subjects.

Duplex-Ultraschalluntersuchung der Venen der unteren Extremitäten bei chronischer Veneninsuffizienz

Hintergrund: Die Duplex-Ultraschalluntersuchung ist der Goldstandard zur Beurteilung von Morphologie und Hämodynamik der Venen der unteren Extremitäten. Das in der vorliegenden Arbeit beschriebene Projekt wurde auf Grund einer Initiative der UIP (Union Internationale de Phlébologie) ins Leben gerufen. Das Ziel war es, einen Konsens internationaler Experten zu erreichen, wie die Methodologie der bildlichen Darstellung mittels Ultraschall zur Untersuchung der Anatomie von oberflächlichen Venen sowie von Perforantes verwendet werden kann. Design: Konsensuskonferenz, die zu einem Konsensusdokument führte. Methoden: Die Autoren führten eine systematische Literatursuche über die Duplex-Anatomie der oberflächlichen Beinvenen sowie der Perforantes durch. Im Anschluss wurde eine internationale Expertengruppe zur Teilnahme an diesem Projekt eingeladen. Elektronische Eingaben der Autoren sowie der internationalen Experten waren allen Teilnehmern auf der UIP-Website zugänglich. Die Autoren bereiteten ein erstes Dokument vor, welches auf dem UIP-Kongress in San Diego 2003 diskutiert wurde. Das überarbeitete Manuskript wurde im Anschluss an alle Experten geschickt und die Kommentare trugen zu weiteren Revisionen des Dokuments bei. Die endgültige Version wurde von allen Teilnehmern akzeptiert. Resultate: Die Experten sprachen detaillierte Empfehlungen für die Duplex-Untersuchung der Venen der unteren Extremitäten sowie über die Interpretation der Befunde und Messergebnisse aus. Dieses Dokument enthält eine detaillierte Methodologie für eine komplette Beurteilung der oberflächlichen Venen sowie der Perforantes der unteren Extremität mit Duplex-Ultraschall. Schlussfolgerung: Die Autoren und eine große Expertengruppe einigten sich auf eine Methodologie zur Untersuchung der Venen der unteren Extremitäten mittels Duplex-Ultraschalls mit spezifischer Bezugname auf die Anatomie der wichtigsten oberflächlichen Venen sowie der Perforantes bei Gesunden und Varizen-Patienten.

[Duplex ultrasound investigation of the veins in chronic venous disease of the lower limbs--UIP consensus document part I: basic principles]

OBJECTIVES

Duplex ultrasound investigation has become the reference standard in assessing the morphology and haemodynamics of the lower limb veins. The project described in this paper was an initiative of the Union Internationale de Phlébologie (UIP). The aim was to obtain a consensus of international experts on the methodology to be used for assessment of veins in the lower limbs by ultrasound imaging.

DESIGN

Consensus conference leading to a consensus document.

METHODS

The authors invited a group of experts from a wide range of countries to participate in this project. Electronic submissions from the experts were made available to all participants via the UIP website. The authors prepared a draft document for discussion at a UIP Chapter meeting held in San Diego, USA in August 2005. Following this meeting a revised manuscript was circulated to all participants and further comments were received by the authors and included in subsequent versions of the manuscript. Eventually all participants agreed to the final version of the paper.

RESULTS

The experts have made detailed recommendations concerning the methods to be used for duplex ultrasound examination as well as the interpretation of images and measurements obtained. This document suggests a methodology for complete assessment of the superficial and perforating veins of the lower limbs, including recommendations on reporting results and training of personnel involved in these investigations.

CONCLUSIONS

The authors and a large group of experts have agreed to a methodology for the investigation of the lower limbs venous system by duplex ultrasonography.

Duplex Ultrasound Investigation of the Veins in Chronic Venous Disease of the Lower Limbs—UIP Consensus Document. Part II. Anatomy

OBJECTIVES

Duplex ultrasound investigation has become the reference standard in assessing the morphology and haemodynamics of the lower limb veins. The project described in this paper was an initiative of the Union Internationale de Phlébologie (UIP), The aim was to obtain a consensus of international experts on the methodology to be used for assessment of anatomy of superficial and perforating veins in the lower limb by ultrasound imaging.

DESIGN

Consensus conference leading to a consensus document.

METHODS

The authors performed a systematic review of the published literature on duplex anatomy of the superficial and perforating veins of the lower limbs; afterwards they invited a group of experts from a wide range of countries to participate in this project. Electronic submissions from the authors and the experts (text and images) were made available to all participants via the UIP website. The authors prepared a draft document for discussion at the UIP Chapter meeting held in San Diego, USA in August 2003. Following this meeting a revised manuscript was circulated to all participants and further comments were received by the authors and included in subsequent versions of the manuscript. Eventually, all participants agreed the final version of the paper.

RESULTS

The experts have made detailed recommendations concerning the methods to be used for duplex ultrasound examination as well as the interpretation of images and measurements obtained. This document provides a detailed methodology for complete ultrasound assessment of the anatomy of the superficial and perforating veins in the lower limbs.

CONCLUSIONS

The authors and a large group of experts have agreed a methodology for the investigation of the lower limbs venous system by duplex ultrasonography, with specific reference to the anatomy of the main superficial veins and perforators of the lower limbs in healthy and varicose subjects.

Duplex ultrasound investigation of the veins in chronic venous disease of the lower limbs--UIP consensus document. Part I. Basic principles

OBJECTIVES

Duplex ultrasound investigation has become the reference standard in assessing the morphology and haemodynamics of the lower limb veins. The project described in this paper was an initiative of the Union Internationale de Phlébologie (UIP). The aim was to obtain a consensus of international experts on the methodology to be used for assessment of veins in the lower limb by ultrasound imaging.

DESIGN

Consensus conference leading to a consensus document.

METHODS

The authors invited a group of experts from a wide range of countries to participate in this project. Electronic submissions from the experts were made available to all participants via the UIP website. The authors prepared a draft document for discussion at a UIP Chapter meeting held in San Diego, USA in August 2003. Following this meeting a revised manuscript was circulated to all participants and further comments were received by the authors and included in subsequent versions of the manuscript. Eventually all participants agreed the final version of the paper.

RESULTS

The experts have made detailed recommendations concerning the methods to be used for duplex ultrasound examination as well as the interpretation of images and measurements obtained. This document suggests a methodology for complete assessment of the superficial and perforating veins of the lower limbs, including recommendations on reporting results and training of personnel involved in these investigations.

CONCLUSIONS

The authors and a large group of experts have agreed a methodology for the investigation of the lower limbs venous system by duplex ultrasonographpy.

The Use of Pressure Change on Standing as a Surrogate Measure of the Stiffness of a Compression Bandage

OBJECTIVES

To measure interface pressure and stiffness of short-stretch and long-stretch bandages applied with variable strength. These parameters have a deciding influence on the efficacy of compression therapy in chronic venous disease.

DESIGN

Prospective experimental study.

MATERIALS AND METHODS

Compression bandages constructed of different materials were applied with light, moderate and high pressure. Interface pressure was measured over the medial aspect of leg in 12 healthy individuals. Long-stretch bandages were compared to short-stretch bandages. The difference between standing and supine pressure was used to characterise stiffness.

RESULTS

In the low pressure range the median pressure of the final bandage in the supine position was between 18 and 30 mmHg for the long-stretch and 25-33.5 mmHg for the short-stretch bandages (p<0.01, Mann-Whitney U-test). The median differences between standing and supine pressure were between 2.0 and 8.5 for the long-stretch and 6.0-10.5 mmHg for the short-stretch material. In the group of moderate pressure the median values in the supine position were in a range 33.0-58.0 mmHg, for long-stretch and 39.0-49.5 mmHg for short-stretch bandages, with an increase after standing of 6.0-7.0 mmHg with long-stretch, and 14.0-21.0 mmHg with short-stretch bandages (p<0.01, Mann-Whitney U-test). The median supine pressure values in the high pressure group were between 52.0 and 67.0 mmHg for long-stretch and 59.5-67.0 mmHg for short-stretch material. The median increase during standing ranged between 8.5 and 14.5 mmHg in the elastic group and 23.0-33.0 in the inelastic group (p<0.01, Mann-Whitney U-test).

CONCLUSION

A bandage applied with light pressure corresponds to the moderate pressure category of stockings. The difference between the sub-bandage pressure from supine to standing can be used to characterise the stiffness of a bandage.

The venous return simulator: an effective tool for investigating the effects of external compression on the venous hemodynamics – first results after thigh compression

Background: To present a virtual model, the venous return simulator (VRS), designed to compute venous hemodynamic variations when compression is applied to the leg. Methods: The VRS defines a numerical network of the lower extremity and computes the dynamic variables (flow rate, venous diameter and internal pressure) for a defined external pressure. The VRS was based on physiological data from the literature and clinical studies on healthy subjects. Clinical correlations were required to confirm its validity; for this purpose, we carried out experiments simulating the conditions of a clinical trial, in which the diameter of superficial and deep veins was measured while increasing pressures (20, 40 and 60 mmHg.) were applied to the thighs of patients enduring deep valvular insufficiency and venous ulcers. The diameters and flow rates calculated using our VRS model were compared with the experimental data obtained at the same thigh compression levels. Results: The numerical results of VRS are in good agreement with the clinical data obtained by Duplex, (R2 = 0.96). In accordance with the in vivo measurement the computed results show that only a pressure greater than 40 mmHg is able to reduce the venous diameter at thigh-level, both in the great saphenous vein and in the femoral vein. Conclusion: The venous return simulator computes lower limb hemodynamic parameters under static conditions. The good correlation existing between the VRS and the data obtained in a previous clinical study shows that this numerical approach could provide a useful means of predicting the hemodynamic consequences of compression therapy.