Physical Therapy in the Treatment of Venous Leg Ulcers: Biophysical Mechanisms
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In a fraction of a second, a large area of the human body can be imaged with a thermal resolution approaching 50 mK, as well as a spatial resolution of 25 µm–50 µm.6
Infrared imaging also simplifies documenting dynamic responses to stimuli.7,8 Thirty years of clinical use and hundreds of peer-reviewed studies in the medical literature have established that thermography is a safe and effective means to examine the human body.
Today, infrared thermal imaging has become one of the most efficient techniques for evaluating skin temperature. Modern infrared digital cameras, employing advanced focal-plane array technology, provide a sensitive diagnostic tool for a multitude of clinical situations, ranging from breast cancer screening to open heart surgery.
The present study is the first clinical experiment to use infrared imaging to assess the thermal effect, as a result of increased blood flow in the ulceration, after physical therapy treatments. Only 1 other study in the literature has measured thermal effect as a hemodynamic reaction inside venous leg ulcers.2 In their opinion, thermography from the video sequences is a clear indication of the extent of skin heating during treatment. In larger, deeper ulcers, there is a characteristic warm area along the ulcer rim, which is presumably due to increased blood flow of the tissue in this area.
The CT is thought to restore valvular competence and reduce or suppress superficial and deep venous reflux. There are various methods of CT, including specialized compression stockings, elastic and inelastic compression bandages, and intermittent pneumatic compression systems. Blood flow will vary greatly according to the compression system applied and types of materials used. The precise mode of action of compression is not fully understood, but numerous perceived benefits have been proposed,9–11 including decrease in edema, softening of lipodermatosclerosis, acceleration of venous flow back toward the heart, decrease in venous volume, reduction in venous reflux, and improvement in lymph drainage.
Partsch et al11 investigated the decrease of venous filling index (VFI) after various methods of CT. In their study, the initial values of VFI without compression were in the pathological range (median 8.45 mL/sec), and were consistent with massive refluxes in all cases. The short-stretch bandage applied with a pressure of 20 mmHg diminished VFI to a median of 3.25 mL/sec, while the elastic bandage approached 4.25 mL/sec with a pressure of 40 mmHg. At 40 mmHg, this nonelastic bandage produced values that are nearly normal (2.2 mL/sec), and a further increase of compression pressure to 60 mmHg provided relatively minimal improvement (1.3 mL/sec). The elastic bandage had to be applied with 60 mmHg to obtain normal values (2.0 mL/sec).
The present findings show that one biophysical mechanism of CT is improvement of arterial blood circulation inside the wound with the use of medical compression stockings that provide pressure 25 mmHg–32 mmHg at the ankle (eg, in venous leg ulcer therapy, capillaries near the surface transport heat via blood flow into deeper layers, and increased capillary blood flow near the surface of the skin expands blood flow areas). Better blood microcirculation produces a therapeutically usable field of heat in the tissue and accelerates the healing process. Based on the results of a previous clinical study,5 the authors concluded that CT is the most effective physical method in venous leg ulcer healing.