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Biomedical subjects

A J Brakkee

Publications and source records attributed to A J Brakkee.

At least 19 recordsLinked to original sources
PubMed2000

Venous reflux has a limited effect on calf muscle pump dysfunction in post-thrombotic patients.

The purpose of the present study was to evaluate the relationship between calf muscle pump dysfunction (CMD) and the presence and location of valvular incompetence. Deep vein obstruction might influence CMD, and so venous outflow resistance (VOR) was measured. VOR and calf muscle pump function were measured in 81 patients, 7-13 years after venographically confirmed lower-extremity deep venous thrombosis. The supine venous pump function test (SVPT) measures CMD, and the VOR measures the presence of venous outflow obstructions, both with the use of strain-gauge plethysmography. Valvular incompetence was measured using duplex scanning in 16 vein segments of one leg. Venous reflux was measured in proximal veins using the Valsalva manoeuvre, and in the distal veins by distal manual compression with sudden release. Abnormal proximal venous reflux was defined as a reflux time of more than 1 s, and abnormal distal venous reflux as a reflux time of more than 0.5 s. No statistically significant relationship was found between the SVPT and either the location or the number of vein segments with reflux. Of the 81 patients, only nine still had an abnormally high VOR, and this VOR showed no relationship with the SVPT. In conclusion, venous reflux has a limited effect on CMD, as measured by the SVPT. The presence of a venous outflow obstruction did not significantly influence the SVPT. Duplex scanning and the SVPT are independent complementary tests for evaluating chronic venous insufficiency.

Adult↗
PubMed1990

[Basic principles of compression therapy].

The empirically established positive effects of the compression in the syndrome of the chronic insufficiency of the veins are widely accepted. Nevertheless the theoretical interpretation of these effects is often difficult, and even, depending on the criterion chosen, contradictory results can be yielded, particularly with regard to the influence on the pumping function of the veins. The experiences concerning these compression effects are reported, taking into consideration the non-linear relation between venous pressure and volume of the extremities and paradoxical results are explained.

Bandages↗
PubMed1986

The measurement and modelling of the mechanical properties of human skin in vivo--I. The measurement.

The mechanical properties of human skin in vivo are studied by means of uniaxial strain measurements. In order to obtain a stress-strain relationship which is independent of the in vivo measuring configuration, values for the effective width and effective length of the loaded skin strip have to be known. By variation of tab width and tab distance in a few series of experiments on the same subject, these effective values are found. In order to obtain a time independent stress-strain relationship a correction procedure is introduced. In this procedure the time dependent (viscoelastic) effects are described and subtracted from the total response.

Biomechanical Phenomena↗
PubMed1986

The measurement and modelling of the mechanical properties of human skin in vivo--II. The model.

The stress-strain relationship for human skin in vivo has a characteristic non linear shape even for low loads. Considerations are given on the basis of which a structural model has been selected, in which the mechanical properties of corrugated collagen fibrils are involved. It is found that such a model can describe the experimental stress-strain relationship surprisingly well with only three free parameters. These parameters are related to basic collagen fibril properties such as stiffness, diameter and waviness. The role of elastin is likely to be negligible for the purely elastic properties of human skin in vivo.

Biomechanical Phenomena↗
PubMed1985

[Skin blood flow measurement in microangiopathic changes].

The classical Martorell-ulcer, which is--according to the original criteria--rather rare, is preceded and accompanied by characteristic microangiopathic signs, the so-called "Pigmented Praetibial Patches" (PPP's). These signs are of great diagnostic significance. In complicated pathology it is important to measure skin blood flow and especially the reactions on a temporary arterial occlusion and on the application of a vasodilating ointment. For this purpose a method is used, based upon measurement of heat transport in the superficial 1.5 mm of the skin.

Humans↗