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Hemodynamics study with CVI patients Compression therapy reduces capillary hypertension

Issue 02/2020

In patients with chronic venous insufficiency (CVI), movement triggers a pressure increase in the capillaries of the feet and can damage the smallest vessels in the long term. Dr. med. Anja Oelert, Specialist in Skin and Venereal Diseases, et al. proved that compression stockings are able to significantly reduce capillary hypertension.

life: With intact vessels, tensing the calf muscles supports blood flow into the smallest vessels as well as venous return flow to the heart. But what happens in the long term with patients suffering from chronic vein problems?

Dr. Oelert: In our currently published, clinically experimental pilot study1, we have been able to show for the first time that activation of the “calf muscle pump” triggers an excessively fast pressure increase at capillary level in patients with a backlog of blood in the veins caused by CVI. We were also able to prove that compression therapy in the form of a well-adjusted compression stocking can prevent an excessively fast pressure increase in the smallest capillaries. The significance of the healthy capillary bed’s elasticity for the regulation of microcirculation, i.e. the exchange of essential nutrients and oxygen as well as removal of harmful substances and CO2, was not known until then. High capillary pressure can, therefore, potentially lead to increased damage and even the destruction of the smallest capillaries. This microangiopathy manifests itself, for example, in a comparative decrease in capillary numbers and in other morphological damage, such as microthrombosis in the minute vessels of the skin. Clinically, this damage can be reflected in patients with chronic venous insufficiency, for example, in the form of known skin changes, such as hyperpigmentation, hardening of the skin or even painful venous ulcers.

Dr. med. Anja Oelert is a practicing specialist in skin and venereal diseases in Heidelberg, Germany.

What effect do compression stockings have in this case?

Dr. Oelert: We were able to show that a well-adjusted medical compression stocking significantly increases the time needed to reach the maximum capillary pressure when the CVI patients’ muscle pumps were activated. Increasing damage, such as a reduction in skin capillaries, can therefore be scaled back or at least compensated. This allows us to assume that the clinically proven effect of compression stockings helps to improve blood flow in the smallest vessels.

How were you and your team able to prove this?

Dr. Oelert: We conducted the study in an air-conditioned clinical laboratory under strictly standardized conditions. The patients were seated, with the foot to be examined fixed on a special microscopy table to exclude movement artefacts. The capillary pressure was then measured in a capillary loop in the nail fold of the big toe, using specifically developed measuring micropipettes made of glass.e uniformly recorded the capillary pressure in accordance with the “servo-null” method. Patients had CVI proven by duplex ultrasound. Two patients also demonstrated clinically venous ulcers, and three patients had skin abnormalities in the form of lipodermatosclerosis.
A blood pressure cuff was attached around the calf to standardize and simulate the muscle pump: the blood pressure cuff was inflated to 60 mmHg within two seconds and left like that for exactly 60 seconds.
We then used computer-aided measurements to record the exact pressure curves and evaluated them in a standardized way. At the same time, patients’ ECG readings, skin temperature, blood pressure and heart rate were recorded for the duration of the examination. We conducted this study with and without compression stockings, for example, to analyze the progression of the pressure curves up to the maximum pressure point in the smallest nail fold capillaries of the big toe. We used the VenoTrain ulcertec compression stocking in our study. The result of the evaluation was that the capillary pressure in the capillary loops increased much more quickly without compression stockings than with compression stockings, i.e. on average by 5.65 mmHg/s. With compression stockings, the average increase was 2.47 mmHg/s. The duration up to the maximum capillary pressure with compression stockings was 23.40 seconds on average and was therefore significantly slower. Without compression stockings, the average time up to the maximum capillary pressure was 11.35 seconds.
For the very first time, we were able to provide clinical evidence with this study showing that treatment with compression stockings prevents a rapid pressure increase in the smallest capillaries. Medical compression stockings help improve blood flow in the smallest vessels and thus can substantially support healing of venous ulcers in a purely mechanical way.

“The compression stocking significantly increased the time needed to reach the maximum capillary pressure.”
Dr. med. Anja Oelert

How did the patients respond to the stocking?

Dr. Oelert: The CVI study patients felt that the stockings were very pleasant and praised their high degree of wearing comfort. It is one of the few compression stockings that can also be used by patients with painful venous ulcers. That’s why it was particularly suitable for our study.

Which quality requirements should compression stockings meet to counteract the high ambulatory blood pressure in the capillaries?

Dr. Oelert: The consistent contact pressure of 36 mmHg, i.e. compression class 3, was particularly important to us. VenoTrain ulcertec has this contact pressure and therefore significantly prevents venous reflux from proximal to distal, that means it reduces the pathological increase in capillary pressure to a large extent. And, as mentioned before, it’s an advantage that patients with venous ulcers can wear this stocking, i.e. patients with clinically very advanced venous insufficiency.

1  Oelert A. et al.: Medical compression stockings reduce hypertension of nailfold capillaries at the toe of patients with chronic venous insufficiency, Clin Hemorheol Microcirc. 2018;69(1–2):115–121.

 

Images: Universität Greifswald, Kerstin Schmid/Fotostudio Sauer


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