The role of low resistance blood flow pathways in the pathogenesis and healing of venous leg ulcers

Dynamics of Cutaneous Laser Doppler Flux with Concentration of Moving Blood Cells and Blood Cell Velocity in Legs with Venous Ulcers and in Healthy Legs

Laser Doppler flux (LDF) is a product of the concentration of moving blood cells (CMBC) and the blood cell velocity (BCV). In an attempt to obtain more information about the cutaneous microcirculation in legs with venous ulcers and in healthy legs, the dynamics of the curves of the LDF, the CMBC, and the BCV were analyzed in 8 patients with venous leg ulcers and in 10 subjects with healthy legs. The curves of the CMBC and of the BCV were found to be in opposite phases both in the ulcerous legs and in the healthy legs. The maximal amplitude of the curves of the LDF and of the CMBC was greater in the legs with ulcers than in the healthy legs (p = 0.021 and p = 0.0085, respectively). The finding that the curves of the CMBC and the BCV were in opposite phase can be interpreted to reflect the capillary blood flow by fits and starts both in legs with venous ulcers and in healthy legs. The greater amplitude of the LDF and the CMBC in legs with venous ulcers reflects the blood flow in anatomically altered capillaries in those legs. It is useful to record the curves of the CMBC and the BCV together with the LDF because this gives additional information about the microcirculation of the skin.

A Review of Microvascular Measurements in Wound Healing

The microcirculatory evaluation in patients affected by arteriopathic or venous ulcers is usually carried out using laser Doppler flowmetry, transcutaneous oxygen (transcutaneous pressure of oxygen, TcPO2), and carbon dioxide (transcutaneous pressure of carbon dioxide, TcPCO2) measurements and capillaroscopy. These techniques provide significant pathophysiologic and prognostic information. TcPO2 and TcPCO2 diagnose and classify the extent of arterial disease in the leg ulcers caused by arterial disease; the prognostic value is recognized, though doubts about its prognostic potential exist in the case of leg ulcer. Laser Doppler flowmetry is able to identify the first functional impairment in the early stages of the arterial disease and in the complicated venous insufficiency. Capillaroscopy gives us morphological and quantitative parameters of the capillary bed that is damaged in arteriopathic and venous ulcers; nevertheless, it does not provide us with definite prognostic indexes. Combining the 3 methods may contribute to yield objective measures in the clinical management of lower extremity ulcers.

Intermittent pneumatic compression: physiologic and clinical basis to improve management of venous leg ulcers

Venous leg ulcers (VLUs) are a significant health problem that afflicts 1% of the population at some point during their lifetime. Intermittent pneumatic compression (IPC) is widely used to prevent deep venous thrombosis. However, IPC seems to have application to a broader base of circulatory diseases. The intermittent nature of pulsatile external compression produces beneficial physiologic changes, which include hematologic, hemodynamic, and endothelial effects, which should promote healing of VLUs. Clinical studies of the management of VLUs show that IPC increases overall healing and accelerates the rate of healing, leading to current guideline recommendations for care of patients with VLUs. Proper prescription of IPC to improve the management of patients with VLUs requires further definition. It seems that application of IPC in combination with sustained graduated compression improves outcome in patients with the most advanced venous disease.

A descriptive study of skin temperature, tissue perfusion, and tissue oxygen in patients with chronic venous disease

Chronic inflammation and microcirculatory disturbances of the skin have been implicated as causative factors of complications associated with chronic venous disease (CVD). The purpose of this study is to describe the mean differences between and correlations among three measures of microcirculation: skin temperature (Tsk), tissue perfusion/blood flow (BF), and tissue oxygen (tcPO(2)) of CVD-inflamed skin compared to normal controls. In a convenience sample of 55 patients with CVD (n = 31) and without CVD (n = 24), Tsk was measured with an infrared thermometer, BF with a laser Doppler flowmeter, and tcPO( 2) with a transcutaneous oximeter across three measurements periods 1 week apart (Times 1, 2, and 3) at the medial aspect of both lower legs. Tsk was higher (1.2 degrees C) across all measurement periods (p < .05), BF was higher at Times 1 and 3 (p = .002 and .012, respectively), and tcPO(2) was lower at Times 1 and 3 (p = .013 and .050, respectively) in the CVD group as compared to the non-CVD group. BF and Tsk were positively correlated at Times 1 and 2 (r = .516, p < .005; r = 0.278, p = .04) but not at Time 3 (r = 0.235, p > .05). No consistently significant correlations were found between tcPO(2) and BF or tcPO(2) and Tsk (p > .05). Tsk and BF were higher in the skin of lower legs affected by CVD than in those not affected. Pathological processes in the skin produce heat detectable by an infrared thermometer. Measurement and monitoring of Tsk can augment clinical findings and guide treatment when localized inflammation is suspected. Future studies of Tsk should be directed toward the usefulness of infrared technology to develop a CVD leg ulcer prediction model.

Use of intermittent pneumatic compression in the treatment of venous ulcers

Venous ulcers affect up to 1% of the population. This review provides the hemodynamic, hematologic and clinical effects of intermittent pneumatic compression (IPC) in the treatment of venous ulcers. It presents the different IPCs and their application on venous disease. It points out that a large randomized study on IPC versus standard four-layer compression in the treatment of venous ulcers is needed. The cost–effectiveness of IPC in the treatment of venous ulcers should also be assessed.

Microcirculation Disturbances in Patients with Venous Ulcer before and after Healing as Assessed by Laser Doppler Flux-Metry

BACKGROUND

We studied whether a characteristic pattern of laser Doppler flux (LDF) could be identified in perimalleolar skin of patients with venous ulcer before and after ulcer healing.

METHODS

Nine subjects with venous ulcer that healed after conservative treatment in 1-6 months and nine healthy persons were included in the study. Microcirculation investigations of laser Doppler flux (LDF) were carried out before and after ulcer healing at rest, upon arterial occlusion, during thermal stimulation and during experimental venous hypertension.

RESULTS

Resting LDF expressed as median and range (in arbitrary perfusion units) was significantly higher in patients with venous ulcer in comparison to healthy subjects: 60.6 (40.2-156.5) vs. 9.2 (6.5-19.5), p=0.008. During thermal stimulation and during postischemic reactive hyperemia, absolute values of LDF were slightly but significantly higher in patients with venous ulcer than in healthy subjects, but indices of hyperemic reactivity were very low in patients (median postischemic LDF increase to 101.8 vs. 450.0% in healthy controls, p=0.008; and thermally induced LDF increase to 125.5 vs. 881.5% in healthy controls, p=0.008. Experimental venous hypertension (cuff pressure 40 and 70 mmHg, respectively) led to an equally pronounced relative reduction of LDF in healthy persons as in patients with venous ulcer before and after ulcer healing, but the absolute values of flow remained about six to seven times higher in patients when compared to healthy subjects. Hyperemic reactivity and venoarteriolar response did not change after ulcer healing.

CONCLUSIONS

Elevated basal LDF and preserved maximal LDF during reactive hyperemia were found in perimalleolar skin of patients with venous ulcers that eventually healed. The relative venoarteriolar response was preserved in spite of elevated absolute values of LDF during experimental venous hypertension. These hemodynamic characteristics remained unchanged after epithelialization of venous ulcers.

Intermittent pneumatic compression as an adjuvant therapy in venous ulcer disease

Despite improvements in healing rates venous ulcer disease still carries significant morbidity and cost. Any therapy that further improves healing rates is worthy of consideration. The recognised effects of intermittent pneumatic compression (IPC) on both arterial and venous circulation suggest that its use may confer significant benefits to venous ulcer healing. This study investigates the potential additive effects of adjuvant IPC on the healing and subsequent prevention of venous ulcers. Some improvement in the rate of healing in venous ulcers is noted. These findings are set against a background of very high healing rates in both treatment and control groups. No benefit is seen to accrue if IPC is used as an adjuvant therapy to help prevent recurrence of ulcers although the study period is very short.

The use of intermittent pneumatic compression in venous ulceration

Even with the application of four-layer bandaging, the recommended treatment for venous leg ulceration, patients with reduced mobility have delayed ulcer healing. Intermittent pneumatic compression (IPC) has an established role in deep vein thrombosis prophylaxis and has been shown to influence fibrinolysis, tissue oxygenation, oedema and venous return. It has also been suggested, but not yet proven, that IPC may improve the healing of venous leg ulcers. An extensive review of the literature has demonstrated that the use of this treatment on patients with reduced mobility has not been previously studied; yet, analysis of difficult-to-heal ulcer patients would indicate that this method of treatment may be appropriate and requires further study.

The influence of local heating on skin microcirculation in pressure ulcers, monitored by a combined laser Doppler and transcutaneous oxygen tension probe

In a prospective, controlled study the skin microcirculation and transcutaneous oxygen tension were evaluated in 28 elderly patients (85 +/- 0.8 years) with grade 2 and 3 pressure ulcer. Laser Doppler fluxmetry and transcutaneous oxymetry techniques were used together in a combined probe to simultaneously evaluate the influence of heat stress at 44 degrees C, at the same time and in the same area of the ulcer edge. Total skin microcirculation was already increased at rest before heating, and increased even more during a fast and then a more gradually heat-induced hyperaemia response compared with undamaged skin. The increase showed a biphasic manner. On the other hand, the oxygen diffusibility from the capillaries to the skin surface was significantly reduced, compared with undamaged skin. One hypothesis may be that in ageing skin the main part of the increased skin microcirculation in a pressure ulcer were passing through thermoregulatory vessels in subpapillary tissue layers. Interactions between the increased blood flow and metabolic activity at the ulcer edge might be oxygen-consuming, leading to reduced oxygen content passing through the capillaries and contributing to tissue ischaemia. Disturbances of the local skin microcirculation and tissue oxygenation will influence the ulcer healing rate and may affect the healing progress.