Air plethysmography in chronic venous insufficiency: clinical diagnosis and quantitative assessment

Ambulatory venous pressure, air plethysmography, and the role of calf venous pump in chronic venous disease

BACKGROUND

Ambulatory venous pressure (AMVP) records pressure dynamics with calf exercise. Air plethysmography (APG) measures related volume detail. APG has been suggested as a noninvasive surrogate for AMVP. We examine the correlations between APG and AMVP parameters and the role of "calf pump failure" in chronic venous disease (CVD).

METHODS

A total of 8456 limbs in 4610 patients investigated for CVD during a 20-year period were analyzed. APG and AMVP data were available in 4599 limbs for calculation of Pearson correlation coefficient; 1347 of these limbs had significant iliac vein stenosis, proven by intravascular ultrasound. Venn diagrams are used to explore overlapping incidence of APG and AMVP abnormalities.

RESULTS

APG calf volume and reflux (venous volume, venous filling index) showed progressively significant deterioration with advancing Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) clinical class, anatomic extent of reflux (superficial, deep, perforator), and reflux severity (axial reflux, segmental score). Notably, calf ejection volume increased in a nearly linear fashion (R = 0.71) to venous volume such that residual volume fraction (RVF) remained normal even in the worst of these categories. AMVP too progressively deteriorated with clinical disease and reflux severity. Venous filling time was the key parameter as the pressure drop alone was abnormal in only 4% of the limbs analyzed. There was no correlation between RVF and AMVP (R = 0.22) or between AMVP and many other APG parameters. Venn distribution showed only minor overlap (30%) between AMVP and key APG abnormalities overall, but the overlap increases from 40% to 70% in advanced clinical and reflux categories. AMVP was rarely abnormal (7%) when APG was normal. Median AMVP was normal in calf pump failure categories, however defined (subnormal ejection fraction, RVF, or both). Median AMVP is normal in venous obstruction without reflux, while AMVP abnormalities are associated three to seven times more with reflux than with obstruction.

CONCLUSIONS

APG (venous filling index) is a useful index of reflux. Calf pump ejection is a powerful and plastic compensatory mechanism, and calf pump failure is rare. Ambulatory venous hypertension is dominantly associated with reflux and less with obstruction. AMVP too worsens with clinical and reflux severity categories. However, there is little correlation between APG and AMVP parameters as APG measures volume and AMVP measures pressure, each in its own domain, and the volume-pressure curve is nonlinear. AMVP may be omitted in routine clinical testing if APG is normal, as the yield (7%) will be very low. AMVP reflects venous hypertension, the end stage in CVD. AMVP should be used to identify such cases when APG is abnormal.

The clinical importance of air plethysmography in the assessment of chronic venous disease

Air plethysmography is a non-invasive test that can quantify venous reflux and obstruction by measuring volume changes in the leg. Its findings correlate with clinical and hemodynamic measures. It can quantitatively assess several components of venous hemodynamics: valvular reflux, calf muscle pump function, and venous obstruction. Although clinical uses of air plethysmography have been validated, it is used almost exclusively for medical research. Air plethysmography can be used to assess chronic venous disease, to evaluate improvement after venous surgery, to diagnose acute and past episodes of deep venous thrombosis, to evaluate compression stocking therapy, to study the physiological implications of high-heeled shoes in healthy women, and even to evaluate the probability of ulcer healing.

Compression stockings significantly improve hemodynamic performance in post-thrombotic syndrome irrespective of class or length

BACKGROUND

Graduated elastic compression (GEC) stockings have been demonstrated to reduce the morbidity associated with post-thrombotic syndrome. The ideal length or compression strength required to achieve this is speculative and related to physician preference and patient compliance. The aim of this study was to evaluate the hemodynamic performance of four different stockings and determine the patient's preference.

METHODS

Thirty-four consecutive patients (40 legs, 34 male) with post-thrombotic syndrome were tested with four different stockings (Mediven plus open toe, Bayreuth, Germany) of their size in random order: class 1 (18-21 mm Hg) and class II (23-32 mm Hg), below-knee (BK) and above-knee thigh-length (AK). The median age, Venous Clinical Severity Score, Venous Segmental Disease Score, and Villalta scale were 62 years (range, 31-81 years), 8 (range, 1-21), 5 (range, 2-10), and 10 (range, 2-22), respectively. The C of C0-6EsAs,d,pPr,o was C0 = 2, C2 = 1, C3 = 3, C4a = 12, C4b = 7, C5 = 12, C6 = 3. Obstruction and reflux was observed on duplex in 47.5% legs, with deep venous reflux alone in 45%. Air plethysmography was used to measure the venous filling index (VFI), venous volume, and time to fill 90% of the venous volume. Direct pressure measurements were obtained while lying and standing using the PicoPress device (Microlab Elettronica, Nicolò, Italy). The pressure sensor was placed underneath the test stocking 5 cm above and 2 cm posterior to the medial malleolus. At the end of the study session, patients stated their preferred stocking based on comfort.

RESULTS

The VFI, venous volume, and time to fill 90% of the venous volume improved significantly with all types of stocking versus no compression. In class I, the VFI (mL/s) improved from a median of 4.9 (range, 1.7-16.3) without compression to 3.7 (range, 0-14) BK (24.5%) and 3.6 (range, 0.6-14.5) AK (26.5%). With class II, the corresponding improvement was to 4.0 (range, 0.3-16.2) BK (18.8%) and 3.7 (range, 0.5-14.2) AK (24.5%). Median stocking pressure (mm Hg) as measured with the PicoPress in class I was 23 (range, 12-33) lying and 27 (range, 19-39) standing (P < .0005) and in class II was 28 (range, 21-40) lying and 32 (range, 23-46) standing (P < .0005). There was a significant but weak correlation (Spearman) between stocking interface pressure measured directly with the PicoPress and the VFI improvement (baseline VFI-compression VFI) at r = .237; P = .005. Twenty-one patients (legs) changed their preference of compression and 38% of these (8/21 patients, 9/21 legs) preferred an AK-GEC stocking.

CONCLUSIONS

Compression significantly improved all hemodynamic parameters on air plethysmography. However, the hemodynamic benefit did not significantly change with the class or length of stocking. These results support the liberal selection of a GEC stocking based on patient preference.

Avaliação da insuficiência da veia safena magna com classificação C2 e C3 (CEAP) pela pletismografia a ar e pelo eco-Doppler colorido

CONTEXTO: Com a presença de refluxo venoso, há necessidade de avaliar a gravidade clínica da doença pela quantificação do efeito hemodinâmico da incompetência venosa e definição de sua distribuição anatômica. OBJETIVO: Determinar a correlação da pletismografia a ar com o grau de refluxo pelo eco-Doppler na insuficiência da veia safena magna no quadro clínico C2 e C3 da CEAP. MÉTODOS: Foram examinados, prospectivamente, 87 membros com refluxo da veia safena magna determinado pelo eco-Doppler e 32 membros sem sinais ou sintomas de doença venosa. Todos foram submetidos ao exame clínico, pletismografia e eco-Doppler de membros inferiores. Do eco-Doppler foram utilizados os parâmetros: diâmetro da veia safena em sete níveis, velocidade e tempo de refluxo. Da pletismografia foram considerados o índice de enchimento venoso, a fração de ejeção e a fração de volume residual. RESULTADOS: Dos 119 membros, 61 pertenciam à classe C2. Na comparação do diâmetro da veia nos grupos controle e estudo houve diferença estatisticamente significante, exceto ao nível do maléolo. Utilizando-se a Correlação de Spearman para análise dos índices da pletismografia e eco-Doppler foram observadas algumas significâncias, porém o coeficiente de explicação (r²) mostrou que foram fracas. CONCLUSÕES: Os parâmetros da pletismografia não se correlacionam com o grau de refluxo na veia safena magna, pois houve uma correlação muito fraca entre seus valores e o tempo e a velocidade do refluxo. Somente o índice de enchimento venoso tem correlação com refluxo venoso. A fração de ejeção e de volume residual não se mostraram importantes na discriminação da gravidade clínica.

Chronic venous insufficiency: clinical assessment and patient selection

Chronic venous insufficiency is a complex condition, with widely varied clinical manifestations, etiologies, and underlying pathophysiology. An orderly workup is mandatory to assess the nature of a patient's underlying venous disease. This begins in the office setting with a careful medical history, physical examination, and bedside diagnostic tests. These are augmented by confirmatory diagnostic testing, including duplex ultrasonography, venography, plethysmography, and ambulatory venous pressure measurement. Based upon the results of these examinations, the patient's venous disease can be classified according to standardized classification schemes, which in turn leads to the selection of an appropriate treatment strategy. This article outlines the steps in the clinical assessment and classification of patients with chronic venous insufficiency.

Inelastic compression increases venous ejection fraction more than elastic bandages in patients with superficial venous reflux

Aim

To investigate the influence of compression bandages, manufactured using materials with different elastic properties, on the impaired venous pumping function in patients with venous insufficiency.

Methods

Ejection volume (EV) and ejection fraction (EF) were measured using strain gauge plethysmography distal from the patella without and with elastic and inelastic compression bandages in a total of 30 patients with major venous reflux in the great saphenous vein. The interface pressure of the bandages was measured simultaneously in the medial gaiter area. Normal values of EV and EF were obtained from 15 healthy controls.

Results

Patients with venous insufficiency showed a statistically significant reduction of EV and EF compared to controls. Elastic bandages with an average pressure of 42 mm Hg in the supine position achieved a moderate increase of EV and a significant improvement of EF (p < .01), while inelastic bandages applied with comparable resting pressure (41 mm Hg) raised EV and EF into a normal range (p < .001). The improvement of the ejection fraction correlates well with the pressure differences between standing and lying (Static Stiffness Index) and between muscle systole and diastole during exercise (Pearson r = 0.69 and 0.74 respectively, p < .001). Elastic bandages applied with high stretch in order to achieve standing pressures comparable to those of inelastic bandages (>60 mm Hg) led only to a minor improvement of the venous pumping function.

Conclusions

Ejected volume and ejection fraction, which are severely reduced in venous insufficiency, can be increased by compression therapy. Inelastic compression is much more effective than elastic bandages, and is able to normalize venous pumping function. With elastic bandages EV and EF always remain below the normal range even when applied with high stretch producing a resting pressure that is barely tolerable.

Home use of impulse compression of the foot and compression stockings in the treatment of chronic venous insufficiency

PURPOSE

The use of intermittent pneumatic compression, in addition to elastic bandages or stockings, accelerates the healing of leg ulcers in patients with severe chronic venous insufficiency (CVI). There is recent evidence that impulse compression of the plantar venous plexus reduces post-traumatic ankle swelling and prevents postoperative venous thromboembolism. The purpose of this study was to evaluate the clinical and hemodynamic responses after home use of impulse foot compression for 3 months in patients already using therapeutic compression stockings for the management of CVI.

METHODS

Twelve extremities from 9 patients with documented CVI, class 4 to 5 according to the Clinical, Etiology, Anatomy, Pathophysiology classification system, were included in this prospective cohort study. All patients were instructed to use a foot pump device at home for 2 hours a day for 3 months in addition to therapeutic compression stockings (30-40 mm Hg) worn during the day. The device was set to three cycles (3 seconds) of compression (120 mm Hg) per minute. A clinical scoring system was completed before foot compression and 1, 2, and 3 months thereafter. In addition, all patients underwent air plethysmography studies at the same time intervals, including venous volume, venous filling index, ejection fraction, and residual volume fraction.

RESULTS

Patients reported significant improvement in their scores for swelling (P <.05) and pain (P <.04). Air plethysmography showed a reduction in venous volume and venous filling index, although these differences were not significant. Ejection fraction remained unchanged and residual volume fraction was significantly reduced (P <.05) compared with baseline. The foot compression devices were well tolerated by all the patients in the study.

CONCLUSIONS

The use of home foot impulse compression plus elastic stockings significantly reduced the residual volume fraction as measured by air-plethysmography in a group of patients with severe CVI. This favorable hemodynamic response could, in part, explain the clinical improvement achieved by this combined treatment. However, this represents a preliminary pilot study that needs to be confirmed in future randomized controlled studies with more patients included.