Air Plethysmography Research Articles

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. (J Vasc Surg 2001;34:805-11.)

Clinical and Hemodynamic Outcomes in Patients with Chronic Venous Insufficiency After Oral Micronized Flavonoid Therapy

The aim of this study was to prospectively investigate the clinical efficacy of Daflon therapy in patients with mild to moderate chronic venous insufficiency (CVI) (clinical class 1-4) and to assess the changes in venous hemodynamics by using air plethysmography (APG). Fifty-six limbs in 28 patients were studied. They all had primary venous insufficiency with no venous obstruction, and mixed deep and superficial venous incompetence was found in 64% of the limbs. There was a significant decrease in symptom score for swelling and heaviness after 6 months of Daflon therapy. The symptom score for cramps also showed improvement though it did not reach statistical significance. Pain was significantly reduced with a mean pain score of 21.8 +/- 19.3% before comparing to 10.4 +/- 20.2% after 6 months of Daflon therapy (p < 0.01). This was also associated with a decrease in mean calf circumference from 37.0 +/- 4.3 to 36.4 +/- 4.3 cm (p < 0.001). There was no significant change in the venous filling index (VFI), ejection fraction (EF), and residual volume fraction (RVF) before and after 6 months of Daflon therapy (VFI: 3.7 +/- 3.5 vs 3.4 +/- 2.5 mL/s, EF: 54.5 +/- 15.9% vs 57.7 +/- 19.7%, RVF: 41.4 +/- 19.2% vs 39.4 +/- 24.2%). The clinical improvement without associated changes in venous hemodynamics as measured by APG suggests that Daflon mainly works by modifying the microcirculatory environment not detected by APG and this microcirculatory change is associated with clinical improvement. In this regard, Daflon would be especially useful for symptomatic relief in patients with functional venous insufficiency who do not have clinical evidence of varicose veins but suffer from symptoms of venous insufficiency.

Improved hemodynamic effectiveness and associated clinical correlations of a new intermittent pneumatic compression system in patients with chronic venous insufficiency

Purpose: A new intermittent pneumatic compression device (SCD Response System) has recently been shown in healthy volunteers to have the ability to detect the postcompression refilling of the calf veins and to respond by initiating the subsequent cycle when these veins are full. This has proven to be more effective in expelling blood proximally than the conventional intermittent pneumatic compression device (SCD Sequel System). The aim of this study was to test the influence of venous disease on the postcompression refill time detected by means of the SCD Response and the effectiveness of the new system in expelling blood in patients who have venous reflux caused by post-thrombotic syndrome or varicose veins. Methods: This open, controlled trial was conducted in an academic vascular unit with 10 patients who had post-thrombotic syndrome and 10 patients who had varicose veins. The new SCD Response System was tested against the existing SCD Sequel System in both legs in the supine, semirecumbent, and sitting positions. The refilling time sensed by means of the device was correlated with the venous filling index by using air plethysmography. The total volume of blood expelled per hour during compression was compared with that expelled by the SCD Sequel System in the same volunteers and in the same positions. Results: An inverse association was found between the mean postcompression refilling time in the sitting position and the venous filling index of the apparently healthy or less severely affected leg (r = –0.52, P =.019), the refill time being significantly shorter in patients with advanced venous disease. The SCD Response System increased the volume expelled per hour in the post-thrombotic leg, when compared with the SCD Sequel System, by 109.9% (P =.005) in the supine position, by 85.1% (P =.009) in the semirecumbent position, and by 40.2% (P =.005) in the sitting position. The corresponding results in the more severely affected leg in patients with varicose veins were 71.9% (P =.005) in the supine position, 77.9% (P =.005) in the semirecumbent position, and 55.7% (P =.013) in the sitting position. Similar improved results were also found in the contralateral leg in both groups. Conclusions: The deflation settings of the new SCD Response System are able to be adjusted selectively, correlating with the physiological severity of chronic venous insufficiency. By achieving more frequent compression cycles, the new system is more effective than the current one in expelling blood proximally, confirming our earlier findings in healthy volunteers. Further studies testing a possible improved efficacy in preventing deep venous thrombosis in this high-risk group are justified. (J Vasc Surg 2001;33:915-22.)

Air plethysmography: an alternative method for assessing peripheral circulatory adaptations during spaceflights.

A new approach to the study of peripheral vascular hemodynamics in microgravity was initiated by designing an alternative methodology: air plethysmography (AP). This is the only technique that enables the quantification of vascular hemodynamics from gross measurements performed on the limbs. This paper reports a description of the device and of the measurement protocol. A comparative study showed that AP yields results that are well correlated, although not in agreement, with those obtained by means of the reference method in the laboratory (mercury strain gauge plethysmography, MSGP; for venous capacity, correlation coefficient r = 0.8, P < 0.0001, limits of agreement--0.9 ml.100 ml-1 and 1.4 ml.100 ml-1; for arterial flow index, correlation coefficient r = 0.7, P < 0.0006, limits of agreements -20.4 ml.min-1 and 37.2 ml.min-1; for half-emptying time, correlation coefficient r = 0.9, P < 0.0001, limits of agreement -0.88 s and 0.77 s), and that are characterized by good reproducibility (coefficient of variation in general lower than 12%). Preliminary findings during spaceflight, on board the Mir Space Station, yielded data that is expected to improve our knowledge of vascular deconditioning in conditions of weightlessness.

Diagnosis and endovascular treatment of iliocaval compression syndrome

Purpose: The purpose of this study was to evaluate the clinical presentation, diagnosis, and endovascular treatment of iliocaval compression syndrome (ICS). Patients and Methods: During a 3-year period, 18 patients (17 women, 1 man; mean age, 42 years) presented with clinical and imaging findings consistent with ICS. All patients were evaluated with venography and Doppler ultrasound (DUS), 13 of 18 with intravascular pressure measurements, 12 of 18 with intravascular ultrasound, 9 of 18 with air plethysmography (APG), and 4 of 18 with magnetic resonance venography. Seventeen patients were treated with endovascular stenting, one was treated with angioplasty alone, and six received adjunct thrombolysis. Results: Despite the presence of stenosis or occlusion in all cases, APG indicated no iliac vein obstruction (outflow fraction ≥ 40%) in nine patients. DUS revealed acute (6) or chronic (7) unilateral iliofemoral deep venous thrombosis in 13 of 18 patients, whereas the results of five of 18 DUS studies were normal. Recanalization and stent placement (n = 17) or angioplasty (n = 1) was achieved in all patients. The average pressure gradient was 5.6 mm Hg preprocedure and 0.6 mm Hg postprocedure. The primary patency rate demonstrated with DUS (n = 17) and venography (n = 7) at 6 months was 89%. The primary patency rate at 12 months was 79%. Conclusions: ICS often presents as sudden unilateral left lower extremity pain and swelling in young to middle-aged female patients after pregnancy, surgery, or a period of inactivity. Venography, intravascular ultrasound, and magnetic resonance venography demonstrate high sensitivity, whereas APG–outflow fraction demonstrates low sensitivity in the diagnosis of ICS. Endovascular stenting and angioplasty provide safe and effective early and intermediate-term treatment of symptomatic ICS. (J Vasc Surg 2001;34:106-13.)

Air plethysmography: The answer in detecting past deep venous thrombosis

Purpose: In this study we assessed the accuracy of air plethysmography (APG) as a means of detecting earlier deep venous thrombosis (DVT), in comparison with venography, to develop a preoperative test for patients with varicose veins. Methods: In this retrospective analysis of prospectively acquired data, 202 patients referred with the clinical suspicion of chronic venous obstruction (224 lower limbs) and 41 patients (41 lower limbs) who had symptoms and signs suggestive of DVT, but had deep veins that appeared normal on venography, were studied with both venography and APG. Results: The results of venography were negative for past DVT in 169 legs and confirmed past DVT in 96 limbs. The DVTs were confined to the calf in 19 limbs and were found at popliteal level, more proximal, or both in 77 limbs. A total of 95% of the limbs that had earlier proximal DVT (73 of 77) were identified by means of an APG outflow fraction with occlusion of the superficial veins in the first second (OFs) of less than 28%. This is analogous to the Q wave of the electrocardiogram, which is a means of denoting the presence of myocardial infarction. The specificity rate of the method in the detection of past proximal DVT was 96%, the positive predictive value was 92%, and the negative predictive value was 98%. Conclusion: APG is a practical, inexpensive, easy-to-perform, accurate, noninvasive method for the diagnosis of hemodynamically significant (ie, proximal or extensive calf DVT) chronic venous obstruction that could replace venography. (J Vasc Surg 2001;33:715-20.)

Evaluation of duplex ultrasonography versus other investigations in the diagnosis of ‘venous aetiology’ in patients with leg ulcers

Abstract Background The aim was to compare duplex imaging, venography, foot volumetry and air plethysmography in patients with healed leg ulcers considered to be caused by venous disease to discover whether duplex scanning alone could confirm a venous aetiology. The importance of isolated reflux in a segment of the deep system below a competent valve was assessed. Methods A total of 125 patients with 153 healed leg ulcers was examined. An Acuson (Mountain View, California, USA) scanner was used to detect reflux lasting for more than 0·5 s in the deep, superficial and calf perforating veins; the findings were compared with those obtained with ascending venography, foot volumetry and air plethysmography. Results Thirteen legs showed no reflux on duplex imaging, but ten of these had abnormal foot volumetry and 12 had abnormal plethysmography. Venography showed post-thrombotic change in 26 legs, but there was evidence of deep venous scarring in only six on duplex ultrasonography. Eight of 75 legs with a normal venogram had ‘complete’ (thigh-to-calf) deep reflux on duplex imaging. Forty-five legs showed segmental deep reflux on duplex imaging, of which 29 had associated perforating vein incompetence. Mean half-refilling times on foot volumetry were 8·46 s for femoral and 5·84 s for popliteal reflux, compared with 3·84 s in the 33 patients who had thigh-to-calf reflux (P &amp;lt; 0·05). Conclusion Absence of reflux in all venous segments on duplex imaging does not exclude a venous aetiology for ulceration. Segmental femoral and popliteal incompetence on duplex imaging is usually associated with other sites of valvular incompetence, but depresses calf function less than thigh-to-calf reflux.

New experiences with absolute ethanol sclerotherapy in the management of a complex form of congenital venous malformation

Background: Complex forms of congenital venous malformation have defied proper classification and confounded therapy. Through a newly designed multidisciplinary approach, these venous defects were properly diagnosed and classified according to the Hamburg classification. Absolute ethanol was adopted as a new scleroagent for this complex form of venous defects to improve overall treatment results with acceptable morbidity and recurrence rates. Patients and Methods: Among 318 patients aged 2 months to 60 years (130 men: mean age, 24.6 years; 188 women: mean age, 24.5 years), 143 patients were confirmed as having venous defects predominantly (45%). We conducted diagnostic evaluation with magnetic resonance imaging, whole body blood pool scan, duplex scans, transarterial microalbumin lung scans, air plethysmography, bone x-ray film, and angiography. Thirty of 143 patients were indicated for the absolute ethanol sclerotherapy for the complex form of venous defects, and they completed 98 sessions of multistage therapy with direct puncture technique. Follow-up assessment (minimum, 6 months; average, 10.2 months) was made as early results after completion of therapy. Results: The immediate success rate at the completion of treatment through 98 sessions on 30 patients was 92% (90/98). The reason for the failure of 8% (8/98 sessions) was mainly due to the lesion's inaccessibility to the nidus to deliver the alcohol safely. On follow-up assessment available on 28 of 30 patients, overall improvement of the lesions with good to fair response on clinical assessment was obtained in 27 (96%) of 28 patients. Similar good to fair responses were obtained on whole body blood pool scan assessment (14 [93%] of 15 patients) and also on magnetic resonance imaging assessment (12 [93%] of 13 patients). Various major to minor acute complications developed during the procedure in eight (26.7%) of 30 patients through 16 (16.3%) of 98 sessions of the therapy: ischemic bullae, tissue fibrosis, deep venous thrombosis, pulmonary embolism, peripheral nerve palsy, and temporary pulmonary hypertension. All 24 incidences of complication were successfully managed with full recovery except one case of permanent peroneal nerve palsy that was present during 18 months of follow-up. No single recurrence has been detected to date. Conclusion: Absolute ethanol sclerotherapy alone can deliver excellent results in complex forms of venous malformations with considerable but acceptable morbidity and may be able to reduce the morbidity involved with the conventional surgical therapy alone on complex forms of venous malformation. No recurrence or deterioration of the therapy results was observed during the follow-up period (average, 10.2 months) after the completion of multistaged therapy. (J Vasc Surg 2001;33:764-72.)

Sequelae after limb-sparing surgery with major vascular resection for tumor of the lower extremity

Purpose: Limb-sparing procedures have recently replaced amputations as the treatment for tumors invading major vessels of the lower extremity. Major arteries must be reconstructed for limb salvage. The veins are not usually reconstructed. This study was undertaken to investigate the sequelae such as chronic venous disease after venous resection for tumors. Methods: Ten patients who underwent limb-sparing surgery for a tumor of the lower extremity or retroperitoneum that required major vascular resection were studied. The median follow-up period was 48 months. After combined resection of a major artery and vein, arterial reconstruction was performed. The veins were not reconstructed. The resected veins included the inferior vena cava (n = 2), the external iliac and common femoral veins (n = 3), the superficial femoral vein (n = 3), and the popliteal vein (n = 2). The main outcome measures were clinical classification of chronic venous disease in 10 patients and air plethysmography in seven patients. Results: Clinical classification was C0A in 6 patients, C3A in 1 patient, C3S in 2 patients, and C4S in 1 patient. Venous claudication with uncontrollable edema was observed in two patients with C3S disease. Pain and itching with inflammatory skin changes were observed in one patient with C4S disease. These three patients had undergone resection of the femoral vein, including the deep femoral vein along with proximal adductor muscles. Air plethysmography revealed that the ejection fraction was significantly lower and the residual volume fraction was significantly higher in the three patients with symptoms than in symptom-free patients. Conclusions: Significant chronic venous disease was observed in the patients who underwent combined resection of the femoral vein, the deep femoral vein, and the adductor muscles for a tumor. (J Vasc Surg 2001;33:694-9.)

Changes in venous hemodynamics after superficial vein surgery for mixed superficial and deep venous insufficiency.

The purpose of this study was to determine the hemodynamic changes after superficial vein surgery in patients with mixed superficial and deep venous insufficiency (MVI). Between July 1996 and June 1998, all patients with MVI together with saphenofemoral reflux were evaluated prospectively with air plethysmography (APG) and duplex scanning before and 1 month after superficial vein surgery. Saphenofemoral flush ligation without stripping was performed with multiple small incisions for avulsion of varicosities. Seventy-eight patients with 102 operated limbs were included for analysis. The venous filling index (VFI), ejection fraction (EF), and residual volume fraction (RVF) improved significantly after superficial vein surgery (mean VFI 5.99 +/- 3.39 vs. 1.82 +/- 1.21 ml/s, p < 0.001; mean EF 48.39% +/- 11.74% vs. 52.78% +/- 14.33%, p < 0.05; mean RVF 49.80% +/- 11.18% vs. 36.19% +/- 12.98%, p < 0.001, respectively, before and after operation). The proportion of limbs with deep venous incompetence on duplex scanning at more than one site decreased from 70% to 44% after operation. The mean number of sites with deep venous incompetence decreased from 2.14 +/- 0.96 to 1.52 +/- 1.21 after operation (p < 0.001). In conclusion, superficial vein surgery resulted in significant improvement in hemodynamic parameters in limbs with MVI. There was also abolition of deep venous reflux after superficial vein surgery alone. Superficial vein surgery should be the first line of treatment in limbs with MVI, with deep vein reconstructive surgery reserved for those not responding to superficial vein surgery.

A Contrivance for Assessment of Lower Extremity Venous Function Using Air Plethysmography

A Contrivance for Assessment of Lower Extremity Venous Function Using Air Plethysmography

Diagnosis and Treatment of Varicose Veins

Varicose veins are dilated, tortuous veins exhibiting reflux because of valvular insufficiency. Dilatation of veins may be primary, that is, initiated by an unknown process, or may be the result of postthrombotic changes, arteriovenous fistula, or diverted flow resulting from a blockade of deep veins. Theoretical causes of varicose veins are heredity, race, gender, posture, gravitational back pressure, pregnancy, hormonal influence, weight, primary and secondary valvular incompetences, incompetent perforating veins, arteriovenous communications, and vein wall weakness. Visual inspection and palpation permit a clinical classification with respect to many different factors, especially the type of varix and the clinical stage of chronic venous insufficiency. Refluxes play a decisive role in the pathogenesis of large varices. They are usually detected over the sapheno femoral junction or the saphenopopliteal junction. Identification of these refluxes needs Doppler ultrasonographic techniques. Highly effective noninvasive examination methods have become available and include photoplethysmography, air plethysmography, portable Doppler ultrasound, and duplex scanning. The sole invasive diagnostic technique is ascending or descending phlebography. Several different treatments have been recommended for varicose veins. Flush ligation combined with stripping, avulsion of local varicosities, and perforator interruption are still the most common surgical techniques. The aim of varicose vein surgery is the removal of diseased incompetent vein segment and the control of reflux. Development of new sclerosing agents renders sclerotherapy for varicose veins more effective, and use of Doppler and the duplex ultrasound techniques provides a better hemodynamic and anatomic precision, which ultimately improves the treatment efficacy. Because patients seek treatment for varicose veins most commonly for cosmetic reasons, recently developed lasers and intense pulsed light(IPL) have become the methods for treating telangiectasia. In summary, surgery treats the major venous reflux, sclerotherapy treats the feeding venous system, and the laser or IPL seals effectively the superficial vessels.

The value of air plethysmography in predicting clinical outcome after surgical treatment of chronic venous insufficiency

Purpose: The role of air plethysmography (APG) as a predictor of clinical outcome after surgery in venous disease is yet to be defined. The purpose of this study was to investigate the value of APG in predicting clinical outcome after venous surgery for chronic venous insufficiency (CVI). Methods: Seventy-three extremities in 71 patients with Class 3 through 6 CVI were assessed preoperatively with CEAP (c linical, e tiologic, a natomic, p athophysiologic) criteria, standing reflux duplex ultrasound scan, and APG with measurements of preoperative venous filling index (VFI), venous volumes, ejection fraction, and residual volume fraction. After surgical treatment of the affected limbs, repeat APG studies were obtained within 6 weeks. Established venous reporting standards were used for follow-up to calculate clinical symptom scores (CSSs) in each patient. Results: Superficial venous reflux occurred alone in 24 limbs or in conjunction with perforator incompetence in 26 limbs. Deep and superficial reflux, with or without perforator incompetence, was found in 16 limbs, and seven limbs had isolated deep insufficiency. Follow-up was available in 60 of 71 patients (mean period, 44.3 months). Postoperative APG demonstrated significant hemodynamic changes after surgery as measured with VFI, venous volumes, ejection fraction, and residual volume fraction. Mean CSSs decreased from 7.35 ± 0.56 preoperatively to 1.79 ± 0.32 at late follow-up after surgery (P <.001). With the use of logistic regression, the parameter correlating most closely with clinical outcome was the VFI. A normal postoperative VFI (≤ 2 mL/s) predicted a good clinical outcome (CSS ≤ 2) in follow-up patients, with a positive predictive value of 94%, a specificity of 89%, and a sensitivity of 70%. Conclusions: Normalization of the VFI after venous surgery for CVI is predictive of a good clinical outcome. This APG measurement may be a useful parameter to predict adequacy of surgery in patients with venous insufficiency. (J Vasc Surg 2000;32:961-8.)

Alterations in Lower Extremity Venous Hemodynamics Associated with Normal Pregnancy

This study was performed to define physiologic changes in lower extremity venous hemodynamics during and after normal, healthy pregnancy. Lower extremity venous physiology was evaluated by using air plethysmography in 24 healthy primigravid females (48 extremities) with no known venous disease. All patients were studied during their first, second, and third trimester, and at 6 weeks, 3 months, and 6 months postpartum. Data were evaluated for changes over time and for differences between the right and left lower extremity by use of repeated measures analysis of variance. None of the patients developed overt signs of venous reflux during pregnancy although there was an increase in venous filling index in advanced stages of pregnancy. All values remained within normal range (1.0-1.7 mL/sec, p = 0.52). There was a statistically significant decrease in residual volume fraction that reached a nadir during the third trimester and returned to below-baseline values immediately postpartum (p = 0.02). An increase in venous outflow fraction was demonstrated as pregnancy progressed (p = 0.05). This trend peaked during the third trimester. Calf muscle pump function did not change appreciably during the study period (p = 0.61). There was no difference between right and left lower extremities with regard to venous filling index (p = 0.25), residual volume fraction (p = 0.33), venous outflow fraction (p = 0.17), or calf muscle pump function (p = 0.33). Some alterations in venous hemodynamics are associated with pregnancy. Venous outflow fraction overall is increased coincident with a decrease in residual volume fraction. The significant decrease in residual volume fraction and augmentation in venous filling index may be related to venous dilation and an increase in venous capacitance secondary to hormonally influenced smooth muscle relaxation.

Superficial Vein Valve Repair with a New External Valve Support (EVS)

The aim of this international multicenter trial was to evaluate the effects of a new surgical device (Gore External Valve Support-EVS) and technique for external valvuloplasty of the long saphenous vein (LSV). Patients with superficial venous disease and venous hypertension due to pure superficial venous incompetence were randomized into two treatment groups, the first treated with "conventional treatment" (ligation or stripping) and the second with external valvuloplasty with the EVS. Patients with uncomplicated varicose veins within the age range of 35-65 years were included. Incompetence with presence of functional cusps at the saphenofemoral junction (SFJ), with vein dilatation were the main inclusion criteria. The EVS comprised of a GORE-TEX patch material (including a nitinol frame) that is placed around the vein, producing a reduction in the caliber of the vein. Also the vein section becomes elliptical. These combined actions are aimed to reduce incompetence, allowing a better closure of the cusps. The EVS was placed at the SFJ after limited dissection of the vein and ligation of collaterals. The procedure was randomized as an alternative to simple ligation or stripping (according with the procedure commonly used in the center). The associated ligation of distal incompetent veins was allowed. The main outcome measures of the study were evaluated by color-duplex (morphologic findings and evaluation of reflux) and with ambulatory venous pressure (AVP) or air-plethysmography (APG). Main endpoints of the first year of the study and main subject of this report (mainly concerning safety within the first year of follow-up) were considered presence/absence of reflux; patency of the veins; mobility/function of vein cusps; occurrence of thrombosis; tolerability of the device; and increased complexity and operating time needed for the EVS. At 1 year 30 patients had been randomized (14 EVS implanted, 16 controls). Reflux was absent in all EVS patients, all treated veins were patent, and all cusps were mobile. No thrombosis had been observed and the tolerability of the device was very good. The increased complexity required by placing the EVS was limited (5-12 minutes more). In conclusion results of the first year show efficacy and tolerability of the EVS. In selected patients (superficial LSV incompetence, reflux-dilatation, functional SFJ cusps, incompetence mainly due to enlargement of the vein), the EVS could be an effective alternative to "destructive" ligation and/or stripping of the vein. Prolonged follow-up will indicate the clinical potentials of the EVS.

Quantitative assessment of superficial venous insufficiency using duplex ultrasound and air plethysmography.

The purpose of this study was to quantitatively evaluate venous reflux in limbs with isolated superficial venous insufficiency using color duplex ultrasound. In addition, air plethysmography (APG) was used to investigate possible correlations of duplex-derived peak velocity, duration of reflux, and CEAP classification. One hundred and forty-six legs in 109 patients with isolated superficial venous insufficiency refluxing throughout the length of the limb were selected for prospective study by duplex scan. Reflux was defined as duration of reflux >/=0. 5 seconds. This study was conducted in a university hospital. Venous reflux was evaluated with the patients standing, by the duration of reflux, retrograde peak velocity, reflux volume at the saphenofemoral and saphenopopliteal junction as well as the greater saphenous vein in the thigh. Values obtained by APG were the venous volume (VV), venous filling index (VFI), ejection fraction (EF), and residual venous fraction (RVF). A significant difference was defined as P <.05. Three groups of limbs were analyzed: group A limbs with a retrograde peak velocity greater than 30 cm/second and a duration of reflux of less than 3 seconds; group B with a retrograde peak velocity >/=30 cm/second and a duration of more than 3 seconds; and group C with a retrograde peak velocity of less than 30 cm/second and a duration of reflux of more than 3 seconds. Groups A and B contained 103 limbs, and 24 of these were in CEAP class 5 and 6. Group C contained 43 limbs, none of which were in class 5 or 6. APG demonstrated significant reflux in group A, and VFI was significantly higher compared to group B and group C (P =.0007 and P =.0064, respectively). A significant correlation was demonstrated between peak retrograde reflux velocity and VFI. Severe chronic venous insufficiency is found in limbs with high reflux velocity (greater than 30 cm/second) and the duration of reflux does not correlate with severe chronic insufficiency.

Lack of Tourniquet Effect of Below-Knee Stockings

Objective: To determine whether below-knee compression stockings impede venous return by a tourniquet effect. Design: Randomised, cross-over clinical trial. Patients: Ten outpatient women suffering from mild or moderate primary varicose veins without skin trophic disorder. Methods: Air plethysmography with venous occlusion (50 mmHg) was used to measure arterial inflow (AI), venous volume (V50) and maximum venous outflow (MVO), without stockings and when wearing French class 1 (10-15 mmHg) and class 2 (15-20 mmHg) below-knee stockings. Results: No carry over due to the cross-over design was detected. There was no significant variation in MVO induced by class 1 (44 vs 45 ml/s) or class 2 (42 vs 41 ml/s) stockings. AI decreased significantly with class 2 (0.93 vs 1.22 ml/s, /? = 0.012) but not with class 1 (1.22 vs 1.20 ml/s) stockings. V50 did not change with class 1 (97 vs 95 ml) but decreased with class 2 (80 vs 98 ml, p = 0.031) stockings. Conclusion: No tourniquet effect of class 1 and class 2 below-knee stockings was observed. Venous capacity and arterial inflow were reduced by class 2 stockings.

Assessment of the Treatment of Great Saphenous Varicose Veins Using Air Plethysmography

Assessment of the Treatment of Great Saphenous Varicose Veins Using Air Plethysmography

Abnormal venous function in patients with homozygous sickle cell (SS) disease and chronic leg ulcers

Chronic leg ulceration is a major cause of morbidity in homozygous sickle cell (SS) disease in Jamaica. These ulcers have features in common with venous ulcers in patients with a normal haemoglobin genotype (AA). Thus we sought to determine whether there is abnormal venous function in the legs of patients with SS disease who have ulcers. Experiments were performed on 15 SS patients with ulcers, and on 15 SS patients and 15 AA subjects with no history of leg ulcers. Changes in venous blood volume of the bottom one-third of the leg induced by venous occlusion and release were studied by air plethysmography, providing indices of segmental venous capacitance (SVC), maximal venous outflow (MVO) and venous emptying time (VET). The changes in volume (ambulatory volume change; AVC) induced by a period of leg exercise were also measured at the ankle (AVCa) and calf (AVCc); venous refilling times at these sites (RTa and RTc respectively) were also measured. Finally, cutaneous red blood cell flux recovery time (FRT) after ankle exercise was assessed by laser Doppler flowmetry. Measurements were also made of haematological variables. SVC, MVO and VET did not differ between the groups, indicating no deep venous obstruction in the SS patients with ulcers. AVCc, AVCa and RTc did not differ among the three subject groups. However, compared with AA subjects, SS patients with ulcers had reduced RTa and FRT. Moreover, RTa and FRT were further shortened in SS patients with ulcers relative to SS patients without ulcers. Since the levels of anaemia were similar in SS patients with and without ulcers, these differences cannot be attributed to differences in arterial flow secondary to anaemia. These results suggest abnormal venous function in SS patients with ulcers, relative to both AA subjects and SS patients without ulcers. We propose that there is incompetence of venous valves draining the ankle region of SS patients with ulcers: the consequent raised venous pressure contributes to the slow healing and, possibly, to the onset of leg ulceration in SS disease.

Microvascular response in patients with cardiogenic shock.

To examine the mechanisms contributing to decreased microvascular blood flow in cardiogenic shock by comparing patients with cardiogenic shock with critically ill controls and with patients with septic shock. Prospective, consecutive entry of patients meeting the criteria for septic shock, cardiogenic shock, and critical illness without coexisting infection or shock. University hospital, medical intensive care unit, coronary care unit, and respiratory care unit. Eight patients with cardiogenic shock secondary to acute myocardial infarction, six critically ill controls, and six patients with septic shock. Forearm blood flow was measured at rest and during reactive hyperemia by venous air plethysmography. Red cell deformability was determined by filtration. Leukocyte aggregation was detected by the leukergy test. Neutrophil CD11b/CD18 expression and soluble intercellular adhesion molecule-1 levels were also measured. In cardiogenic shock, forearm arterial resistance was significantly increased at rest and during reactive hyperemia compared with controls and patients with septic shock. The response to reactive hyperemia was attenuated in cardiogenic and septic shock patients, as measured by the absolute change in forearm blood flow from baseline, which was significantly less as compared with controls (p < .01). The percent change in forearm blood flow during reactive hyperemia compared with forearm blood flow at rest was significantly lower in cardiogenic shock (60+/-10) and in septic shock (50+/-11) compared with controls at baseline (145+/-20; p < .01). Red cell deformability was significantly decreased in cardiogenic shock (1.2+/-0.2 mL/min; p < .05) and septic shock (1.1+/-0.2 mL/min; p < .05), compared with controls (1.8+/-0.1 mL/min). Neutrophil CD11b/CD18 expression, leukergy, and serum intercellular adhesion molecule-1 levels in cardiogenic shock patients were not significantly different from controls. These data suggest that the response to reactive hyperemia is attenuated in cardiogenic shock. This appears to reflect increased vasoconstriction and an impaired capacity for vasodilation. Decreased erythrocyte deformability may also be important in limiting systemic microvascular flow. However, evidence supporting a role for neutrophil-endothelial cell interactions was not observed.