Analysis of the postoperative hemodynamic changes in varicose vein surgery related with small saphenous vein reflux.

PURPOSE: To evaluate the postoperative hemodynamic changes in varicose vein surgery related with SSV reflux using APG. METHODS: Totals of 181 limbs and 178 patients who underwent high ligation and stripping (HLS) (87 limbs), radiofrequency ablation (RFA) (43 limbs), or endovenous laser ablation (EVLA) (51 limbs) for SSV reflux from 1995 to 2022 were enrolled. We measured venous volume (VV), venous filling index (VFI), ejection fraction (EF), and residual volume fraction (RVF) preoperatively and at postoperative one and 6 months. RESULTS: Comparing preoperative results to those at postoperative 1 month, the reduction rates of VV, VFI, and RVF were 27, 53, and 31%, while EF increased by 18% (p < 0.001). Comparing preoperative and postoperative 6 month, the reduction rates of VV, VFI, and RVF were 27, 45, and 35%, while EF increased by 27% (p < 0.001). CONCLUSIONS: There were hemodynamic improvement in the lower leg after varicose vein surgery including HLS, RFA, and EVLA.

Leg volume reduction during tiptoe movement is caused by venous ejection and calf muscle contraction.

OBJECTIVES: To clarify the cause of leg volume reduction during tiptoe movement in the standing position. METHODS: The right legs of 20 participants were assessed. The participants performed tiptoe movement in the supine position, and then stood up and performed the tiptoe movement and ankle dorsiflexion. Leg volume changes were recorded continuously using air plethysmography. RESULTS: Differences between leg volume changes due to tiptoe movement and the refilling volumes were not significantly different between the supine (59 mL) and standing (49 mL) positions, indicating that this amount of motion artifact was included in the downward trace recorded by tiptoe movement in the standing position. CONCLUSIONS: Leg volume reduction during tiptoe movement in the standing position included a significant amount of motion artifacts. Therefore, it may be difficult to accurately measure the ejection volume using tiptoe movement in the standing position.

The athlete's vein: venous adaptations in the lower limbs of endurance athletes.

Endurance exercise induces cardiovascular adaptations; the athletic phenotypes of the heart and arteries are well characterized, but few studies have investigated the effects of chronic exercise on the venous system. The aim of this study was to describe the anatomy and function of lower-limb deep and superficial veins in athletes compared with controls. Endurance-trained athletes and untrained controls (13 males, 7 females per group) were examined using ultrasound to measure vein diameter and flow, and air plethysmography to assess calf venous volume dynamics and muscle pump function at rest, during a single step, ambulation (10 steps) and after acute treadmill exercise (30 min ∼80% age-predicted heart rate maximum). Diameters of three of the seven deep veins assessed were larger in athletes (P ≤ 0.0167) and more medial calf perforators were detectable (5 vs. 3, P = 0.0039). Calf venous volume was 22% larger in athletes (P = 0.0057), and calf muscle pump ejection volume and ambulatory venous volume after 10 steps were both greater in athletes (20 and 46% respectively, P ≤ 0.0482). Following acute exercise, flow recovery profiles in deep and superficial veins draining the leg were not different between groups, despite athletes performing approximately four times more work. After exercise, venous volume and ejection volume were reduced by ∼20% in athletes with no change in controls (interaction, P ≤ 0.0372) and although ambulatory venous volume reduced, this remained greater in athletes. These findings highlight venous adaptations that compensate for the demands of regular endurance exercise, all of which are suited to enhance flow through the lower-limb venous system.NEW & NOTEWORTHY Although much literature exists describing adaptations to the heart and arteries in response to endurance exercise training, less is known about the effects on the venous system. Characteristics of "the athlete's vein" described here include deep and perforator vein remodeling, improved drainage, and greater calf venous volume at rest and on calf muscle pump activation. Following exercise, athletes demonstrated prompt flow recovery and appropriate volume reductions, and veins beneficially adapt to better tolerate the demands of regular physical activity.

Calf extra-Fascial compartment area affects calf muscle pumping action: an air plethysmography and computed tomography study.

OBJECTIVES: We aimed to elucidate whether lower limb extra-fascial compartment and muscle areas affect the calf muscle pumping action on lower limbs. METHOD: This study included 90 patients (180 limbs) who underwent preoperative air plethysmography (APG) and preoperative non-contrast computed tomography (CT) of the lower limbs for diagnosis of unilateral or bilateral primary varicose veins. A correlation between cross-sectional CT images and preoperative APG was confirmed. Cross-sectional CT was used to measure the extra-fascial compartment and muscle areas of the calf. The lower limbs were divided into two groups: those that were normal and those with primary varicose veins. RESULTS: The extra-fascial compartment area was significantly correlated with the ejection fraction in normal (r = 0.388, n = 53, p = 0.004) and varicose limbs (r = 0.232, n = 91, p = 0.027). CONCLUSIONS: In normal and varicose limbs, evaluation of ejection fraction, an indicator of muscle pumping, requires consideration of the extra-fascial compartment area.

Plethysmographic features of calf pump failure in chronic venous obstruction and reflux.

BACKGROUND: Calf pump failure (CPF) is a common concept in chronic venous disease. Dorsal vein pressures were originally used to define the pathophysiology. More recently, an abnormal ejection fraction (EF) and residual volume fraction (RVF) with air plethysmography (APG) have been substituted for its diagnosis. The relationship between reflux and calf pump function has been studied extensively. Reflux is thought to be the main cause of CPF, although other mechanisms may play a secondary role. Data mining in our dataset revealed that CPF is frequently found in nonrefluxive limbs-an unexpected finding. We analyzed the APG features of CPF in nonrefluxive limbs of a large cohort of patients investigated for chronic venous disease in our clinic. Data from refluxive limbs (control) seen over the same period was included for comparison. Venous obstructive pathology was variably present in both subsets. Iliac vein stent outcome in CPF limbs from both subsets is included. The role of obstruction in CPF is currently unknown. METHODS: Records of 13,234 limbs in 8813 patients evaluated for suspected chronic venous disease over a 22-year period were analyzed. Prestent and poststent data in 406 CPF limbs (129 nonrefluxive; 277 refluxive) that underwent iliac vein stenting to correct associated stenosis are included. This is a single-center retrospective analysis of prospectively collected data. Duplex and APG data were available for included limbs. A RVF of more than 50% was defined as CPF. A reflux time of greater than 1 second elicited with automated cuffs in the erect position was defined as reflux. RESULTS: There were 7780 (59%) limbs with reflux and 5454 (41%) that were nonrefluxive. Supine venous pressure, an index of venous obstruction, was elevated in both subsets. The incidence of CPF was 25% in refluxive limbs and 16% in nonrefluxive limbs totaling 2790 limbs. Venous volume and venous filling index were significantly elevated (P = .0001) in refluxive limbs compared to nonrefluxive limbs. The EF was diminished (<50%) in all CPF limbs except in a small fraction (n = 427 [3%]). Stent correction of iliac vein stenosis corrected CPF, normalizing the RVF in both subsets. CONCLUSIONS: CPF frequently occurs in nonrefluxive limbs with incidence only slightly less than in refluxive limbs. An RVF of more than 50% seems to be a practical definition of a CPF; an EF of less than 50% is associated with a RVF of greater than 50% in 97% of analyzed limbs. Prospective identification of CPF in limbs with chronic venous disease may allow more detailed investigation of its cause (preload, afterload, neuromuscular pathology or joint immobility, etc) and direct more targeted treatment than currently practiced.

Effects of leg compression and calf muscle contraction by active ankle motion on venous hemodynamics in sitting individuals.

OBJECTIVES: To clarify the effects of compression and active ankle motion on venous hemodynamics in healthy sitting individuals. METHODS: In the sitting position, 14 participants performed plantar flexion and dorsiflexion of the ankle for 3 s each without compression. Changes in the calf volume were recorded using air plethysmography. Subsequently, the process was repeated with the application of tubular elastic bandage (TEB), followed by anti-thrombotic stocking (ATS). RESULTS: The median interface pressure at the calf was 16 mmHg with TEB and 21 mmHg with ATS. Without compression (N), the median venous volume was 76 mL. This was reduced to 58 mL with TEB and 56 mL with ATS (p < .01 vs. N for both). On the other hand, ejection volume by plantar flexion in N (27 mL) was not significantly changed with TEB (31 mL) or ATS (31 mL). Also, ejection volume by dorsiflexion in N (53 mL, p < .001 vs. plantar flexion) was not significantly changed with TEB (53 mL, p < .01 vs. plantar flexion) or ATS (41 mL, p < .05 vs. plantar flexion). CONCLUSIONS: The venous volume, which is defined as the change in enclosed calf volume from elevation to dependency, in the sitting position reduced similarly with TEB and ATS; however, the ejection volumes did not change significantly. Dorsiflexion exerted a larger ejection volume than plantar flexion in the sitting position.

Residual volume fraction during walking using wireless air plethysmography in patients with chronic deep venous disease.

OBJECTIVE: Traditional air plethysmography (APG) provides a quantitative measure of the residual volume fraction (RVF) after 10 tiptoe movements. The recent development of a wireless Bluetooth (Bluetooth SIG, Inc, Kirkland, Wash) APG device, the PicoFlow (Microlab Elettronica, Padua, Italy), enabled us to measure RVF during normal walking. The aim of our study was to compare the RVF obtained during tiptoeing with RVF obtained during normal walking in patients with deep venous pathology (ie, reflux and/or obstruction). METHODS: A total of 61 consecutive symptomatic patients (27 women and 34 men; median age, 46 years; range, 18-79 years) with chronic venous disease due to deep venous pathology (venous reflux or obstruction, or both) before treatment or persisting after intervention were included in the present study. Of the 122 total limbs examined, 79 were affected by deep chronic venous disease and 43 contralateral limbs were normal with normal deep veins and acted as controls. The APG examination was performed using the PicoFlow device using the standard examination technique. The RVF was calculated from the residual volume at the end of 10 tiptoe movements and also during normal walking. RESULTS: At the end of the 10 tiptoe movements, the mean ± standard deviation RVF was 27.0% ± 13.2% in the limbs with normal deep veins and 38.8% ± 16.9% in the limbs with deep chronic venous disease (P < .001). During walking, when a steady state in volume was reached, the RVF was 26.3% ± 17.8% in the limbs with normal deep veins and 43.1% ± 18.6% in limbs with deep venous disease (P < 0.001). A significant difference was found between limbs with normal deep veins and limbs with deep venous reflux, irrespective of which exercise was performed. However, the mean RVF between the limbs with normal deep veins and those with outflow obstruction in the absence of reflux was significant during walking (P = .012) but not during tiptoeing (P = .212). The mean RVF was higher in the C3 to C6 limbs than in the C0 to C2 limbs with tiptoeing (29.9% ± 14.5% vs 38.3% ± 17.0%; P < .006). Similar results were obtained with walking (29.2% ± 18.0% vs 42.4% ± 18.8%; P < .004). CONCLUSIONS: In limbs with normal deep veins and deep veins with reflux, the RVF measured during walking with wireless APG was similar to the RVF obtained during tiptoeing. However, in the limbs with outflow obstruction in the absence of reflux, the RVF during walking was higher than the RVF after tiptoeing. Our results have shown that the evaluation of RVF during walking is feasible and practical.

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 haemodynamic causes of skin changes in limbs with primary varicose veins.

OBJECTIVES: To investigate the haemodynamic causes of skin changes in limbs with primary varicose veins, which were assessed with air plethysmography. METHODS: Five hundred seventeen consecutive patients with axial reflux in the great saphenous vein (varicose vein group) and 248 normal subjects (normal group) were investigated. Varicose vein group patients were divided into two groups according to whether they did (C4-6) or did not (C2-3) have skin changes. Several parameters obtained using air plethysmography were compared among the normal group, C2-3 and C4-6 patients. RESULTS: Although there was no significant difference in the regurgitation index to quantify venous reflux in C2-3 and C4-6 patients, the maximum arterial inflow rate increased (normal group < C2-3 < C4-6), even in limbs with a small amount of venous reflux. CONCLUSIONS: This study suggests that it is not essential to increase the venous reflux rate in skin change development; rather, it is based on various pathophysiological conditions that increase the arterial inflow rate.

Venous hemodynamics assessed with air plethysmography in legs with lymphedema.

This study was conducted to identify specific abnormalities using the results from air plethysmography in legs with lymphedema. A routine air plethysmography exercise protocol was performed in 31 patients with unilateral leg lymphedema, and the results were compared with those of 53 patients with unilateral great saphenous vein reflux and 15 normal subjects. The venous filling index in legs with lymphedema (2.1 ± 1.2 mL/sec) was smaller than in legs with great saphenous vein reflux (6.4 ± 4.1 mL/sec, p < 0.05), but was not different from that in normal legs (1.9 ± 1.2 mL/sec). The ejection fraction was similar in all groups. The residual volume fraction in legs with lymphedema (35 ± 32%) was larger than that in normal subjects (13 ± 23%, p < 0.05), but was not significantly different from that in the contralateral leg of the lymphedema patients (32 ± 27%). In conclusion, we found no specific air plethysmography findings in uncomplicated lymphedema.

Venous Thromboprophylaxis With Neuromuscular Stimulation: Is It Calf Muscle Pumping or Just Twitches and Jerks?

The common peroneal nerve stimulator (CPNS) is a UK-approved device for reducing venous thromboembolism risk. It resembles a wrist watch and is placed over the common peroneal nerve to fire at 1 electrical impulse/sec. The aim was to quantify the claim that it drives the venous muscle pump and imitates walking. Twelve healthy volunteers performed 10 tip-toe maneuvers and 10 ankle dorsiflexions to imitate walking movements. The reductions in calf volume were recorded using air plethysmography (APG). The common peroneal nerve was stimulated for over 10 seconds at each of the 7 increasing electrical impulse settings, and the volume reductions were measured for comparison. The results are expressed as median (interquartile range) absolute (mL), and percentage reduction in calf volume. Tip-toe and dorsiflexion pumping maneuvers were not significantly different: 59 (33.6-96.1), 81.9% vs 51.4 (34-68.5), 59.7%, respectively ( P = .53). However, they both outperformed the CPNS: 10.8 (7.3-18), 13.2% at P = .002 and P = .002, respectively. Qualitatively, the CPNS registered on the tracings as a small spike (muscle twitch) at low settings, with larger amplitudes (ankle jerk) at higher settings. The CPNS activity spikes were discrete, lasting a median (range) of 0.24 (0.16- .3) seconds. The claim that the CPNS empties veins by pumping is supported statistically. However, the amount is small versus the tip-toe and dorsiflexion maneuvers. Furthermore, the CPNS has a short activity profile on the APG trace. Innovations that produce sustained contraction and involve the posterior calf compartments may improve pumping.

Lower limb venous diameters and haemodynamics during pregnancy and postpartum period in healthy primigravidae.

Objective Analyse venous haemodynamics in healthy primigravidae during pregnancy and in the postpartum. Methods Cohort with primigravidae evaluated in the three trimesters of pregnancy and postpartum. Duplex evaluated venous diameters and reflux; air plethysmography evaluated venous filling index, ejection fraction, residual volume fraction and outflow fraction in both limbs. Results During pregnancy, diameters increased in bilateral common femoral and right infravalvar great saphenous, but returned to first trimester values after delivery. Reflux developed in one woman (5%) in the second trimester and in two more women (15%) in the third trimester. No reflux was detected in postpartum. Bilateral venous filling index was higher during pregnancy. Bilateral ejection fraction and residual volume fraction did not change. Bilateral outflow fraction increased progressively. The right limb outflow fraction in left lateral decubitus was similar. All changes returned to first trimester values after delivery. Conclusions Healthy primigravidae presented changes in lower limbs' veins during pregnancy: diameters in bilateral common femoral and infravalvar great saphenous veins increased; new reflux was developed in 15% of women, but there was no venous hypertension. Calf muscular pump function did not change. All changes returned to first trimester values after delivery.

The clinical importance of air plethysmography in the assessment of chronic venous disease / Importância clínica da pletismografia a ar na avaliação da doença venosa crônica

Abstract 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.

Resumo A pletismografia a ar é um método não invasivo que pode quantificar refluxo e obstrução venosa medindo alterações no volume das pernas. Seus achados se correlacionam com parâmetros clínicos e hemodinâmicos. Ela pode fornecer informações quantitativas dos diferentes componentes da hemodinâmica venosa: refluxo valvular, função de bomba muscular da panturrilha e obstrução venosa. Apesar de ter seu uso clínico validado, a pletismografia a ar é usada quase que exclusivamente para pesquisa. Ela pode ser usada para avaliar a doença venosa crônica, mensurar o ganho hemodinâmico após cirurgia venosa, diagnosticar trombose venosa profunda atual ou prévia, avaliar os efeitos da elastocompressão, estudar as implicações fisiológicas do uso de salto alto em mulheres e também avaliar a probabilidade de cura de uma úlcera venosa.

Reappraisal of the Utility of the Tilt-table in the Investigation of Venous Disease†.

OBJECTIVES: Without gravity opposing drainage, most venous diseases would not exist. Therefore, manoeuvres that assess venous function should include gravity. The aim was to "dose" gravity in subjects using static positions and dynamic angulations on a tilt-table and to assess its effects with air plethysmography (APG) and duplex ultrasound over the femoral vein. METHODS: Three groups (providing n = 11 legs each) were compared. (a) A control group, without clinical or duplex evidence of venous disease. (b) An obstruction group, with past iliofemoral deep vein thrombosis. (3) A reflux group, with primary varicose veins. A manually operated tilt-table ranging from -70° to 40° in the Trendelenburg position provided rapid tilting (<3 s). The changes in calf volume at -70° (almost standing), -45° (reclining), and 40° (legs-up) were recorded with APG, as well as the rate and duration of the changes. The minor diameter of the femoral vein was recorded at the three tilt positions. RESULTS: The results were expressed as median (interquartile range). The total working venous volume (mL) in the reflux group was significantly increased: 202 (180-240) mL versus the controls at 138 (119-198) mL, p = .008, and versus the legs with obstruction at 117 (80-154) mL, p < .0005. The venous drainage index (VDI) in mL/second in the obstructed group was significantly reduced: 7 (6-9.6) mL/second, versus the controls at 17.4 (13.9-27.2) mL/second, p < .0005, and versus the legs with varicose veins at 28.1 (25.4-34.4) mL/second, p < .0005. The venous filling index (VFI) in mL/second in the reflux group was significantly increased: 8.1 (4.2-10) mL/second versus the controls at 1.8 (1-2.1) mL/second, p < .0005. The VDI cut-off point discriminating obstruction was ≤10.8 mL/second and the VFI discriminating reflux was ≥ 2.9 mL/second. The femoral vein diameter was reduced significantly with increasing leg elevation. CONCLUSIONS: Manoeuvres using APG on a tilt-table have the potential to quantify the contributions of global obstruction and reflux (mL/second) in patients with venous disease.

Positioning for Endovenous Laser Ablation: Comparative Study with Thigh Stripping.

We performed a comparative study of surgical outcomes and venous functions between endovenous laser ablation with a 980-nm diode laser (EV group) and thigh stripping (ST group). There were no severe complications and initial success rates were 100% in both groups. In the EV group, preoperative symptoms improved in 94.3% of cases, the venous occlusion rate was 98%, and endovenous heat induced thrombosis had occurred in 11.9% (Class 3: 0.7%) at 12 months after the operation. Although comparative study of postoperative venous function by air plethysmography showed significant improvement in both groups, there was less recovery of postoperative venous function in the EV than in the ST group. (This article is a translation of J Jpn Coll Angiol 2015; 55: 13-20.).

Haemodynamic Performance of Low Strength Below Knee Graduated Elastic Compression Stockings in Health, Venous Disease, and Lymphoedema.

OBJECTIVE: To test the in vivo haemodynamic performance of graduated elastic compression (GEC) stockings using air-plethysmography (APG) in healthy volunteers (controls) and patients with varicose veins (VVs), post-thrombotic syndrome (PTS), or lymphoedema. Responsiveness data were used to determine which group benefited the most from GEC. METHODS: There were 12 patients per group compared using no compression, knee-length Class 1 (18-21 mmHg) compression, and Class 2 (23-32 mmHg) compression. Stocking/leg interface pressures (mmHg) were measured supine in two places using an air-sensor transducer. Stocking performance parameters, investigated before and after GEC, included the standard APG tests (working venous volume [wVV], venous filling index [VFI], venous drainage index [VDI], ejection fraction [EF]) and the occlusion plethysmography tests (incremental pressure causing the maximal increase in calf volume [IPMIV], outflow fraction [OF]). Results were expressed as median and interquartile range. RESULTS: Significant graduated compression was achieved in all four groups with higher interface pressures at the ankle. Only the VVs patients had a significant reduction in their wVV (without: 133 [109-146] vs. class1: 93 [74-113] mL) and the VFI (without: 4.6 [3-7.1] vs. class1: 3.1 [1.9-5] mL/s), both at p <.05. The IPMIV improved significantly in all groups except in the PTS group (p <.05). The OF improved only in the controls (without: 43 [38-51] vs. class1: 50 [48-53] %) and the VVs patients (without: 47 [39-58] vs. class1: 56 [50-64] %), both at p <.05. There were no significant differences in the VDI or the EF with GEC. Compression dose-response relationships were not observed. CONCLUSION: Patients with varicose veins improved the most, whereas those with PTS improved the least. Performance seemed to depend more on disease pathophysiology than compression strength. However, the lack of responsiveness to compression strength may be related to the low external pressures used. Stocking performance tests may have value in selecting those patients who benefit most from compression.

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.

A pletismografia a ar é um método não invasivo que pode quantificar refluxo e obstrução venosa medindo alterações no volume das pernas. Seus achados se correlacionam com parâmetros clínicos e hemodinâmicos. Ela pode fornecer informações quantitativas dos diferentes componentes da hemodinâmica venosa: refluxo valvular, função de bomba muscular da panturrilha e obstrução venosa. Apesar de ter seu uso clínico validado, a pletismografia a ar é usada quase que exclusivamente para pesquisa. Ela pode ser usada para avaliar a doença venosa crônica, mensurar o ganho hemodinâmico após cirurgia venosa, diagnosticar trombose venosa profunda atual ou prévia, avaliar os efeitos da elastocompressão, estudar as implicações fisiológicas do uso de salto alto em mulheres e também avaliar a probabilidade de cura de uma úlcera venosa.

Accuracy of Venous Filling Index on Standing (VFIst) and Pure Regurgitation Index (PRI), a Novel Index Obtained by Air Plethysmography, for Detecting Venous Reflux.

OBJECTIVE: To evaluate the accuracy of venous filling index on standing (VFIst) and a new index named pure regurgitation index (PRI), obtained by air plethysmography, for detecting venous reflux. MATERIALS AND METHODS: One hundred and sixty-one healthy subjects (161 limbs) and 180 varicose vein patients (180 limbs) were investigated. All subjects underwent duplex ultrasonography for verifying venous reflux and air plethysmography to obtain hemodynamic parameters such as VFIst, VFI in the supine position (VFIsu), and the maximum arterial inflow rate. To evaluate the accuracy of VFIst and PRI (= (VFIst - VFIsu)/body mass index), receiver operating characteristics curves were created. RESULTS: The optimal cut-off value, sensitivity, specificity, and area under the curve, obtained from analyzing the receiver operating characteristics curves, of VFIst vs. PRI were 2.058 mL/s vs. 0.059 mL · m(2)/s · kg, 93.3% vs. 90.3%, 88.8% vs. 91.3%, and 0.954 vs. 0.964, respectively. CONCLUSIONS: This study indicates that while both VFIst and PRI are highly accurate indicators of venous reflux, PRI, which is not affected by the arterial inflow rate and body mass index, is slightly superior to VFIst, especially in subjects with greater body mass index.

Pneumatic thigh compression reduces calf volume and augments the venous return.

OBJECTIVES: Reactive hyperaemia following thigh compression increases arterial inflow and venous outflow. The net effect can be measured by changes in calf volume quantified using air-plethysmography. The objective was to investigate the effect of thigh compression on venous return. METHOD: The right legs of 19 consecutive volunteers (14 male), median age 31 (25-56) years, were studied in the supine position using air-plethysmography. The clinical, etiological, anatomical, pathophysiological (CEAP) class was C0. A thigh-cuff, 12 cm wide, was inflated in increments of 10 mmHg, from 0 to 80 mmHg. After each inflation step, the calf volume increased to a plateau and was recorded. At 80 mmHg, the thigh-cuff was deflated suddenly with the calf volume decreasing until baseline. Calf volume changes were recorded and stored for analysis. RESULTS: There was a stepwise increase in the venous volume of the calf with each incremental rise in thigh-cuff pressure up to 80 mmHg (p < .0005, Friedman). The median (interquartile range) increase in venous volume from 0 to 80 mmHg was 87 (65-113) mL (p < .0005, Wilcoxon). The volume change below the original baseline following thigh-cuff release was -16 (-12 to -25) mL (p < .0005, Wilcoxon). CONCLUSIONS: Once optimised, intermittent pneumatic compression of the thigh may have a therapeutic role in augmenting the venous return and reducing leg swelling in patients.

Relationship between Arterial Inflow Rate and Venous Filling Index of the Lower Extremities Assessed by Air Plethysmography in Subjects with or without Axial Reflux in the Great Saphenous Vein.

OBJECTIVE: To evaluate the relationship between arterial inflow rate (AIR) and venous filling index (VFI) in limbs with or without varicose veins, assessed by air plethysmography (APG). MATERIALS AND METHODS: A total of 142 patients (142 limbs) visiting our clinic with leg complaints, but without arterial and venous disease, were defined as the normal group (NG), and 65 patients (65 limbs) with leg varices were defined as the varicose vein group (VG). Both groups underwent duplex ultrasonography and APG to identify venous reflux and measure hemodynamic parameters, respectively. Examinations were performed at the first visit in the NG and before and one month after treatment in the VG. RESULTS: A strong correlation between resting AIR and VFI was found in the NG (r = 0.72) and postoperative VG (r = 0.71). Twenty-two and three limbs in the NG and postoperative VG, respectively, had a VFI over 2.0 mL/s because of the high AIR. In the VG, AIR tended to decrease after treatment (P >0.01). CONCLUSIONS: High leg AIR lead to high VFI measured by APG. AIR and VFI should be measured at the same session to assess venous hemodynamic changes after varicose vein treatment when residual venous reflux cannot be diagnosed with duplex ultrasonography.