A Comparison of Light Reflection Rheography and Duplex Scanning in the Diagnosis of Chronic Venous Insufficiency

This study was presented at the Sixteenth Annual Symposium on Advanced Wound Care and Medical Research Forum on Wound Repair (SAWC), April 28–May 1, 2003, in Las Vegas, Nevada, and was recognized for its excellence in clinical research. Introduction Venous ulcers constitute the majority of all leg ulcers.[1] Venous disease accounts for 1 to 2 percent of the healthcare budgets of European countries.[2] Early signs of chronic venous insufficiency (CVI) are varicose veins and acute lipodermatosclerosis.[3] Progressive changes of CVI include brown hyperpigmentation of the skin caused by extravasation of red blood cells into the dermis following venous hypertension.[4] Dependent edema eventually develops because of fluid leakage from local capillaries.[1] Duplex ultrasound has had a considerable impact on the diagnosis and management of chronic venous disease.[5] Duplex scanning has, therefore, become the gold standard for demonstrating the anatomy of the lower limb and confirming venous reflux in such patients.[6] Light reflection rheography (LRR) is performed routinely in the authors’ leg ulcer clinic as part of the standard leg ulcer assessment in conjunction with a clinical examination to confirm the presence or absence of venous insufficiency. This information is vital in order to plan further management of the patient and to prevent inappropriate compression of the legs in cases where the ulcer is not venous in etiology. All patients are not referred routinely for Duplex ultrasonography. Only patients whose diagnosis needed to be further clarified or those patients who could potentially benefit from vascular surgery were subsequently referred. Duplex scanning is an expensive, time-consuming investigation performed by skilled personnel and entails a waiting list for patients to have this investigation. Thus, a new form of screening for venous disease of the legs is appropriate. The aim of this study was to compare, retrospectively, LRR with Duplex ultrasound results that had been performed on a group of patients who attended the leg ulcer clinic to determine the sensitivity of the LRR test as a screening method in diagnosing patients with venous ulcers. Materials and Methods The records of all patients with venous leg ulcers who attended the leg ulcer clinic at the Churchill Hospital, Oxford, were studied, and those patients who had undergone LRR followed by Duplex ultrasonography were retrospectively identified. The patients’ ages ranged from 35 to 94 years (mean age 66.7 years). A standard leg ulcer assessment on these patients included performing an ankle-brachial pressure index (ABPI) to determine the arterial supply to the lower limb using a handheld 8MHz Doppler instrument (Dopplex II, Huntleigh Diagnostics, Cardiff, United Kingdom). Only patients with an ABPI of >0.8 were considered for the study in order to exclude those with significant arterial disease of the lower limbs. Light reflection rheography. LRR had been carried out on all 42 patients to assess the competency of the veins of the lower limbs using the AV-1000 Haemodynamics instrument (Manufactured by DLH Laumann, Germany; distributed by Haemodynamics Inc., Florida, USA). This is a simple, noninvasive, and cost-effective investigation to assess valve competency of the veins of the lower limb. Infrared rays are beamed into the skin by several selective emitters placed approximately 10cm above the medial malleolus with the patient in the sitting position. The measuring head is also equipped with a thermocouple for the measurement of skin temperature. The thermocouple can accurately measure the temperature of the skin provided it is between 25 and 33°C. The infrared light source is used to assess relative changes in blood volume caused by superficial venous emptying following 10 dorsiflexions of the foot within 15 seconds, as recommended in the instruction manual of the LRR instrument.[7] Changes in blood flow are continuously recorded while the patient performs the exercise program. Muscular exercise causes venous pressure to fall, thereby emptying the skin vessels, which increase the recorded signal or the lightness of the skin. Following this exercise, in a subject with no venous reflux, refilling of the veins occurs as a result of arterial inflow causing a gradual reduction in signal intensity or lightness of the skin (Figure 1). Normal venous refilling time (VRT) is >25 seconds. In patients with venous insufficiency, additional venous reflux accelerates refilling of the vessels. This phenomenon is demonstrated as shortened refilling times on LRR tracings of less than 25 seconds (Figure 2).[7] Duplex venous ultrasonography. This investigation was carried out using an ATL HDI 5000 Duplex Ultrasound Scanner (Advanced Technologies Laboratories, Washington, USA), combining B mode, color Doppler, and spectral Doppler ultrasound. The deep veins were investigated for significant disease including reflux, compressibility, and deep venous thrombosis. Reflux was defined as reverse flow for >0.5 seconds after manual calf compression. The superficial venous system and the perforator veins were also investigated for incompetence. Results Forty-two patients were retrospectively identified as having undergone LRR followed by Duplex ultrasonography. The time lapse between performing LRR and Duplex scans ranged from 2 months to 8 years. Shortened refilling times were observed on LRR tracings, and venous reflux was further confirmed by duplex ultrasonography in 41 patients (97.6%). One patient’s LRR result (2.3%) showed evidence of venous reflux, which was not confirmed by Duplex ultrasonography (Table 1). Discussion Many studies have been carried out using both LRR and Duplex ultrasonography in the diagnosis of venous thrombosis and reflux.8–10 Somjen, et al.,[8] conducted a study using Duplex ultrasonography and LRR to assess the severity of CVI. Advanced stages of chronic venous disease were represented by shorter refilling times due to short saphenous vein reflux and deep venous incompetence.[8] Quantification of venous reflux using a Duplex scanner to measure venous reflux and vein diameter and LRR to measure refilling time was carried out by Mosti, et al.,[9] in order to find a better correlation with the clinical stages of venous disease. These indices were able to differentiate between mild and severe cases of CVI but unable to separate patients at the second stage of venous disease from the third stage. Venous reflux was found to be highly predictable in the ulcer risk assessment.[9] A recent study compared LRR findings and color Duplex ultrasonography (CDUS) for diagnosis and follow up of patients with axillary-subclavian vein thrombosis. Both methods were able to diagnose deep vein thrombosis in the initial acute stage with no false positive cases reported. LRR was found to be more sensitive than CDUS during follow up.[10] A similar study validating air plethysmography (APG), photoplethysmography (PPG), and Duplex ultrasonography in the evaluation of severe venous stasis has also found that photoplethysmography is a sensitive method of detecting reflux, though the specificity was poor and venous refill times could not accurately predict the location of reflux. They concluded that air plethysmography is a better method of evaluating venous reflux than photoplethysmography.[11] In the authors’ clinic, LRR, which is similar in principal to PPG, is used to demonstrate the presence or absence of venous disease and not to locate the site of reflux. The results of this study showed that 97.6 percent of patients’ diagnoses of venous disease by LRR were confirmed using Duplex ultrasonography. Only one patient with an abnormal LRR showed a normal Duplex scan result. Since Duplex ultrasonography is considered the gold standard for diagnosing venous disease, it is possible that this patient gave a false positive result with the LRR. Patient factors are known to influence the LRR curve, as the degree of emptying of the superficial venous system is greatly influenced by dorsiflexion of the foot, i.e., arthritis or other disorders of the ankle. Inability to flex the foot sufficiently reduces the amount of blood pumped into the deep system, leading to poor venous refill, even if the patient has no venous disease. With proper pretesting, instruction, and patient practice, this problem could be eliminated.[7] LRR is, therefore, a sensitive noninvasive technique in diagnosing venous reflux in patients with chronic venous disease and is recommended as a screening method in conjunction with a clinical assessment. Conclusion Studies show that LRR is an important noninvasive diagnostic test in CVI. Due to the large number of patients presenting with venous insufficiency, routine diagnosis by Duplex ultrasonography is expensive and time consuming. Thus, a new form of screening for venous disease is appropriate. In order to determine the proportion of patients likely to require Duplex ultrasonography for further confirmation of their diagnosis and suitability for surgery, LRR along with a clinical assessment could be used as a screening method to diagnose CVI. Large scale prospective studies are recommended to determine the sensitivity and specificity of LRR as a screening method for chronic venous disease. Acknowledgements The authors wish to thank Dr. Robert Dawe, Photobiology Unit, Ninewells Hospital, Dundee, for his invaluable comments on this manuscript.