Digital photoplethysmography in the diagnosis of suspected lower limb DVT: is it useful?

Arterial and venous peripheral vascular assessment using wearable electro-resistive morphic sensors

Peripheral vascular diseases (PVDs) represent a significant burden on global human health and healthcare systems. With continued growth in obesity and diabetes, it is likely that the incidence of these conditions will increase. As many PVDs remain undiagnosed, low-cost and easy to use diagnostic methods are required. This work uses newly developed wearable electro-resistive morphic sensors to assess venous and arterial competence in the lower limbs of 36 healthy subjects. Comparison of this HeMo device was made to currently available benchtop light reflection rheography and photoplethymography devices. Results indicate that HeMo can detect the physiological signals of interest for both chronic venous insufficiency and peripheral arterial disease and all subjects were interpreted as healthy by each system. However, measurement repeatability of HeMo was highlighted as an issue that requires further system development. Furthermore, as HeMo captures changes in a section of limb circumference due to changes in underlying blood movement, rather than at a single point, the recorded signal is typically damped by comparison. This factor should be considered in any future developments.

Risk factors for venous ulceration in patients with varicose veins of lower extremities

The aim of this case-control study was to explore the potential risk factors for venous ulceration in patients with varicose veins of lower extremities and to establish a simplified diagnostic score model. Seventy subjects with varicose veins of lower extremities and venous ulceration were compared with 1164 controls with varicose veins of lower extremities and no history of venous ulceration. Stepwise multivariate logistic regression analysis was used to identify the risk factors for venous ulceration. The steps in developing the diagnostic score model were based on the Framingham Heart study. The area under the receiver operating characteristic curve (AUC) was calculated to assess the diagnostic ability of the diagnostic score model. Multivariate analysis showed that men, overweight, obesity, longer duration varicose veins, deep venous valve insufficiency, low lymphocyte counts, and high fibrinogen content were independently associated with an increased risk of venous ulceration. The AUC for the diagnostic score model was 0.75, which indicated good discriminatory ability. Special attention should be paid to the high-risk group of patients with lower extremity varicose veins. The diagnostic score model might be a useful screening tool for clinicians, policy makers, and patients.

Improvement of occupational leg edema and discomforts (RCT)

BACKGROUND: Edema and subjective leg complaints (e.g. pain, heaviness) after long standing or sitting, are defined as orthostatic leg complaints or occupational edema. Compression hosiery should help to prevent or decrease those symptoms. OBJECTIVE: Assess the effects on leg discomforts and leg volume and wearing comfort in two medical below-knee compression stocking types (A vs. B) with an interface pressure of 18 –20 mmHg and a below-knee-low-pressure support stocking (LPSS) with an interface pressure of 8–10mmHg (C). METHODS: Two different types of below-knee medical compression stockings and a LPSS were examined in this randomized, blinded, crossover trial in volunteers having leg discomforts and edema after being in an upright position during the day. Participants were divided into two cohorts, and each type of stocking was worn for three consecutive days in one week with a subsequent washout phase. The assessment of effects and wearing comfort was ascertained by questionnaires. Volume changes in the lower leg were measured with the Bodytronic 600® (Bauerfeind AG, Zeulenroda, Germany). RESULTS: A significant reduction of lower leg volume (mean stocking A: 204.7 ml; mean stocking B: 153.5 ml; mean stocking C: 48.2 ml) and a significant reduction of the life-quality dimension leg-complaints (p <  0.0001) was achieved by all three types of stockings. Compared to the LPSS both compression stockings decreased the lower leg volume significantly more (p <  0.001) and had a significant better fit (p <  0.001). CONCLUSION: Below-knee medical compression stockings with an interface pressure 18–21mmHg and LPSS with an interface pressure of 8–10 mmHg reduce significantly occupational orthostatic edema and leg discomforts which are due to long standing and sitting activities.

An Examination System to Detect Deep Vein Thrombosis of a Lower Limb Using Light Reflection Rheography

Deep vein thrombosis (DVT) of lower limbs can easily arise from prolonged sitting or standing. Elders and pregnant women are most likely to have this disease. When the embolus of DVT comes to pass the lung, it will become a life-threatening disease. Thus, for DVT disease, early detection and the early treatment are needed. The goal of this study was to develop an examination system to be used at non-medical places to detect the DVT of lower limbs with light reflection rheography (LRR). Consisting of a wearable device and a mobile application (APP), the system is operated in a wireless manner to control the actions of sensors and display and store the LRR signals on the APP. Then, the recorded LRR signals are processed to find the parameters of DVT examination. Twenty subjects were recruited to perform experiments. The veins of lower limbs were occluded by pressuring the cuff up to 100 mmHg and 150 mmHg to simulate the slight and serious DVT scenarios, respectively. Six characteristic parameters were defined to classify whether there was positive or negative DVT using the receiver operating characteristic curves, including the slopes of emptying and refilling curves in the LRR signal, and the changes of venous pump volume. Under the slight DVT scenario (0 mmHg vs. 100 mmHg), the first three parameters, m₁₀, m₄₀, and m₅₀, had accuracies of 72%, 69%, and 69%, respectively. Under the serious DVT scenario (0 mmHg vs. 150 mmHg), m₁₀, m₄₀, and m₅₀ achieved accuracies of 73%, 76%, and 73%, respectively. The experimental results show that this proposed examination system may be practical as an auxiliary tool to screen DVT in homecare settings.

Peripheral vascular disease assessment in the lower limb: a review of current and emerging non-invasive diagnostic methods

BACKGROUND

Worldwide, at least 200 million people are affected by peripheral vascular diseases (PVDs), including peripheral arterial disease (PAD), chronic venous insufficiency (CVI) and deep vein thrombosis (DVT). The high prevalence and serious consequences of PVDs have led to the development of several diagnostic tools and clinical guidelines to assist timely diagnosis and patient management. Given the increasing number of diagnostic methods available, a comprehensive review of available technologies is timely in order to understand their limitations and direct future development effort.

MAIN BODY

This paper reviews the available diagnostic methods for PAD, CVI, and DVT with a focus on non-invasive modalities. Each method is critically evaluated in terms of sensitivity, specificity, accuracy, ease of use, procedure time duration, and training requirements where applicable.

CONCLUSION

This review emphasizes the limitations of existing methods, highlighting a latent need for the development of new non-invasive, efficient diagnostic methods. Some newly emerging technologies are identified, in particular wearable sensors, which demonstrate considerable potential to address the need for simple, cost-effective, accurate and timely diagnosis of PVDs.

Advanced imaging in acute and chronic deep vein thrombosis

Deep venous thrombosis (DVT) affecting the extremities is a common clinical problem. Prompt imaging aids in rapid diagnosis and adequate treatment. While ultrasound (US) remains the workhorse of detection of extremity venous thrombosis, CT and MRI are commonly used as the problem-solving tools either to visualize the thrombosis in central veins like superior or inferior vena cava (IVC) or to test for the presence of complications like pulmonary embolism (PE). The cross-sectional modalities also offer improved visualization of venous collaterals. The purpose of this article is to review the established modalities used for characterization and diagnosis of DVT, and further explore promising innovations and recent advances in this field.

In too deep: understanding, detecting and managing DVT

Venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE), is a serious health and social care problem of the developed world, affecting 1 in 1000 adults every year, and with an annual financial overhead of approximately £640 million. The nature of DVT means that often the condition can go unrecognized until the thrombus becomes an embolus. The pathogenesis of DVT continues to be based on Virchow's triad, which attributes VTE to 'hypercoagulability', 'stasis' and 'intimal injury'. The diagnosis of DVT is often the result of a number of tests performed either sequentially or in combination before mechanical and/or chemical treatment is embarked on. Creating public awareness of DVT and PE is the best way to prevent this condition. Nurses are in an ideal position to discuss the importance of lifestyle changes and other related measures to prevent DVT.

[Thromboembolic disease in orthopedic surgery]

Thromboembolic complications are frequent after orthopaedic surgery of the limbs. Strategies to minimize these complications go from recognize the risk factors of the patient to introduce new antithrombotic drugs, and including general medical care, regional anaesthesia and early mobilization. Based in epidemiological studies, prophylaxis must be extended 4-6 weeks in total hip and knee arthroplasty and in surgery of the hip fracture.

Screening for Deep Vein Thrombosis in Asymptomatic High-risk Patients: A Comparison between Digital Photoplethysmography and Venous Ultrasonography

Objective

To determine the role of digital photoplethysmography in screening asymptomatic patients who are susceptible for developing deep vein thrombosis.

Methods

Three hundred and thirty-seven limbs in 169 patients who were high risk for development of deep vein thrombosis were assessed by ultrasonography digital photoplethysmography and the results were compared.

Results

Thirteen limbs were found to have deep vein thrombosis as demonstrated by ultrasonography. All limbs with a venous refilling time greater than 12 seconds had a normal ultrasonography. Compared with ultrasonography and using refilling time less than 12 seconds as the cutoff point, digital photoplethysmography achieved a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 73.8%, 13.3%, and 100% respectively, for detecting deep vein thrombosis in asymptomatic high-risk patients.

Conclusion

Digital photoplethysmography is a simple, noninvasive, and highly sensitive test for screening of deep vein thrombosis.

Comparing results of digital photoplethysmography in two groups of chronic obstructive pulmonary disease patients with and without high pulmonary artery pressure

Background

Digital photoplethysmography (D-PPG) is a newly introduced method of optical screening of deep vein thrombosis (DVT) by recording changes in the size of limb due to tissue fluid.

Objectives

The objective of this study is to assess the effect of high pulmonary artery pressure (PAP) and consequently increased venous system pressure on D-PPG test results.

Methods

Forty-five patients with and 45 patients without PAP pressure were enrolled in the study and divided into two groups. All the patients had a history of chronic obstructive pulmonary disease (COPD). D-PPG test was performed for both legs of all the patients and the results of the two groups were compared. Also, all patients underwent duplex sonography for ruling out DVT.

Results

Using venous refilling time (RT) of <22 s as the optimal cut-off point, it was found that 32 (35%) legs of patients with and 39 (43%) legs of patients without high PAP had positive D-PPG test. Although the rate of positive D-PPG test was higher in patients with high PAP, this was not statistically significant ( P = 0.28). Moreover, overall correlation between RT and venous pump detected by D-PPG and PAP was r = −0.11 ( P = 0.2) and r = −0.01 ( P = 0.6), respectively.

Conclusion

Our results showed that the rate of positive D-PPG test results is slightly higher in patients with pulmonary hypertension, but this difference is not statistically significant. Therefore, increased PAP could be excluded as a confounding factor of D-PPG test.

The Ulcerated Leg Severity Assessment score for prediction of venous leg ulcer healing

BACKGROUND

The aim of the study was to create a reliable scoring system for the prediction of venous ulcer healing in patients treated with compression.

METHODS

A prospective baseline study to identify risk factors for venous ulcer healing was undertaken between March 1999 and August 2001. All patients were treated with multilayer compression. A number of variables were related to 24-week healing rates. A Cox regression model was used to identify risk factors that predicted ulcer healing, from which a scoring system was developed and validated prospectively between February 2004 and March 2005.

RESULTS

In the baseline study of 229 patients, patient age, ulcer chronicity and venous refill time (VRT) of 20 s or less were identified as risk factors. Using these factors and hazard ratios from the Cox regression analysis, the following formula was devised: Ulcerated Leg Severity Assessment (ULSA) score=age+chronicity-50 (when VRT is greater than 20 s). Patients with an ULSA score of 50 or less had higher 24-week ulcer healing rates than those with higher scores in both the baseline study (P<0.001, log rank test) and the validation study performed in 86 patients (P=0.007, log rank test).

CONCLUSION

The ULSA score may help to identify patients with venous ulcers unlikely to respond to conventional treatment who could be offered alternative therapy.

Meta-analysis of plethysmography and rheography in the diagnosis of deep vein thrombosis

BACKGROUND

Plethysmography and rheography techniques have been widely studied as diagnostic tests for deep vein thrombosis (DVT). This study aimed to systematically review the accuracy of these tests for diagnosing clinically suspected DVT.

METHODS

The following databases were searched: Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club (1966 to 2004), and citation lists of retrieved articles. Studies that compared plethysmography or rheography to a reference standard of ultrasound or contrast venography were selected. Standardised data were extracted and study quality determined against validated criteria. Data were analysed by random effects meta-analysis and meta-regression.

RESULTS

The meta-analysis included 78 studies, reporting 82 patient cohorts. Sensitivity and specificity (95% CI) were: 75% (73% to 77%) and 90% (89% to 91%) for impedance plethysmography, 83% (81% to 85%) and 81% (79% to 82%) for strain-gauge plethysmography, 85% (79% to 90%) and 91% (81% to 95%) for air plethysmography, 91% (87% to 94%) and 71% (66% to 75%) for light-reflex rheography, and 86% (83% to 89%) and 93% (91% to 95%) for phleborheography. Meta-regression was limited by poor reporting of studies. There was some evidence that diagnostic performance depended on the proportion of males in the cohort and reporting of study setting.

CONCLUSIONS

Although plethysmography and rheography techniques add diagnostic value, they have inadequate diagnostic performance to act as a stand-alone test in DVT diagnosis. Evaluation of their role in combination with other tests, or standardised clinical assessment, is required.

Venous thromboprophylaxis in trauma: a review

Venous thromboembolism (VTE) remains a significant cause of morbidity and mortality among trauma patients. In the UK, the Government has recently acknowledged this and, with the impending National Institute for Clinical Excellence (NICE) guidelines, is hoping to provide uniform direction of prophylactic measures for inpatients of all hospital specialties. Numerous comprehensive guidelines currently exist and provide an evidence-based approach to prophylaxis of this potentially preventable condition. This article helps to clarify the current evidence regarding prophylactic measures, along with an introduction to the new NICE guidelines and their place in the management of trauma patients.

Diagnosis, investigation, and management of deep vein thrombosis

Deep vein thrombosis is an important cause of morbidity and mortality worldwide, and its clinical diagnosis is unreliable. This article explains current screening and diagnostic methods as well as treatment