Air Plethysmography Research Articles

The PREPARE pilot RCT of home-based progressive resistance exercises for venous leg ulcers

To establish the feasibility of conducting a home-based progressive resistance exercise programme to improve calf muscle pump function in community-based patients with venous leg ulcers. Participants were randomised to receive a 12-week progressive resistance exercise programme using heel raises in addition to compression. The control was usual care in addition to compression. Randomisation was stratified by ulcer duration and ulcer size. Air plethysmography was used to determine changes in calf muscle pump function from baseline. Changes in ulcer parameters were measured using the SilhouetteMobile device. Forty participants were randomised. There were significantly greater improvements in ejection fraction of the calf muscle in the exercise group compared with the control (usual care) group (mean difference 18.5%, 95% CI 0.03 to 36.6%, p<0.05). Other parameters improved in the exercise group but the mean differences were not significant. Adherence with prescribed exercises was 81% and there was no significant difference in the numbers reporting adverse events. There were also no significant differences in ulcer healing parameters (change in area, percentage change in area, number healed at 12 weeks, time to healing). A community-based randomised trial of progressive resistance exercise is feasible. The prescribed exercises appeared to increase ejection fraction, but the effect of exercise on ulcer healing requires further investigation.

Comparison Of Body Composition Measurement Methods In Female Soccer Players

Optimal body size is important for peak performance in sport. Assessment of body composition provides the coach and athlete with insight into the optimal body weight for performance in a given sport. Laboratory techniques for determining body composition are often not generally available for coaches and athletes because of the complex equipment required for the assessment. Consequently, several techniques have been developed which are more suited for use in the field. However, the accuracy of these techniques has not been fully established in an athletic population. PURPOSE: to compare commonly used techniques for determining body composition against densitometry to determine their accuracy in a specific athletic population. METHODS: Subjects were 18 members of a division I university women‘s soccer team (164.5 ± 1.1 cm; 63.0 ± 1.5 kg). Body composition was determined by dual-energy X-ray absorptiometry (DEXA), air plethysmography (BodPod), bioelectrical impedance analysis (BIA), near infrared reactance, ultrasound, and skinfold fat thickness (3, 4, and 7 site), and compared with the results obtained by densitometry (hydrostatic weighing). RESULTS: Correlations (r2) between densitometry and the other techniques wereTABLECONCLUSION: These results suggest that measures of skinfold thickness, either 3 site (triceps, abdomen, suprailiac) or 4 site (triceps, abdomen, suprailiac, thigh), assuming a competent administrator, provide the most accurate field technique for assessing body composition. Despite the ease of measurement provided by the other field techniques, the accuracy of such techniques is questionable in this population.

Estudo da hemodinâmica venosa por meio da pletismografia a ar no pré e pós-operatório de varizes dos membros inferiores

Contexto: O tratamento cirúrgico das varizes primárias dos membros inferiores deve proporcionar alívio da estase venosa, a fim de evitar a evolução da doença venosa para estágios de maior gravidade clínica. Objetivo: Estudar as alterações da hemodinâmica venosa em pacientes portadores de varizes primárias dos membros inferiores no pré e pós-operatório, utilizando a pletismografia a ar. Método: Foram estudados 63 membros inferiores em 39 pacientes (35 mulheres e quatro homens), com média de idade igual a 46,3 anos, operados no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo, no período de janeiro de 2001 a dezembro de 2004. Os membros inferiores foram classificados de acordo com a classificação CEAP, em critério clínico = C2 a C6 (C2 = 6, C3 = 32, C4 = 15, C5 = 7 e C6 = 3), critério etiológico = Ep, critério anatômico = As e critério fisiopatológico = Pr. Os pacientes foram avaliados por exame clínico pré e pós-operatório, mapeamento dúplex pré-operatório e pletismografia a ar pré e pós-operatória. Resultados: Houve melhora da hemodinâmica venosa no pós-operatório, demonstrada pela diminuição do índice de enchimento venoso e da fração de volume residual e aumento da fração de ejeção nos membros inferiores submetidos à operação de varizes. Conclusão: A operação venosa superficial aliviou a estase venosa e proporcionou adequado tratamento, com o objetivo de interromper a evolução fisiopatológica da doença venosa crônica, em qualquer nível de gravidade clínica.

External banding valvuloplasty for incompetence of the great saphenous vein: 10-year results

External banding valvuloplasty (EBV) of the great saphenous vein (GSV) in patients with varicose veins is still controversial. The present study evaluated the effectiveness of EBV in selected patients with an insufficiency of the GSV after a mean follow-up of 92.6 months. A total of 101 limbs underwent EBV for the treatment of a GSV insufficiency. Thirty-one limbs from 27 patients (three men, 24 women; mean age 44.2 years; range 19 to 58 years) were re-examined and followed for a mean of 92.6 months. The venous volume, venous filling index, ejection fraction and residual venous fraction were analyzed preoperatively and at the follow-up using air plethysmography. The diameter and reflux of the GSV were evaluated using duplex ultrasound. Overall, the mean (± SD) follow-up time was 92.6±22.3 months (range 46 to 138 months). At the follow-up, the preoperative venous hemodynamic states had improved significantly, to the following values: venous volume 96.0±32.3 mL to 83.4±32.6 mL; venous filling index 3.6±2.9 mL/min to 2.4±2.2 mL/min; and residual venous fraction 39.7%±18.6% to 26.1%±16.8% (P<0.05). The diameter of the GSV was 6.4±1.4 mm preoperatively and 4.8±1.7 mm postoperatively (P<0.01). Reflux in the proximal GSV was demonstrated preoperatively in 19 (61.3%) of 31 limbs. During the follow-up period, four limbs (12.9%) had high ligation and stripping of the GSV performed due to the recurrence of varicosity. EBV of the GSV provides good results in terms of the venous hemodynamics and decreasing the diameter of the GSV. EBV may be an alternative procedure to stripping or endovenous ablation therapy in selected patients.

Great Saphenous Vein Sparing Surgery by Angioscopic Valvuloplasty Combined with Axial Transposition of a Competent Tributary Vein – 5-Year Follow-Up

Objective To evaluate the efficacy and haemodynamic effects of great saphenous vein (GSV) sparing surgery – valvuloplasty combined with axial transposition of a competent tributary vein (A-VACT). Materials and methods Eighty-five limbs in 74 patients with isolated GSV incompetence were selected for GSV sparing surgery. After angiographic valvuloplasty, the competent tributary vein was exposed and cut 1.5 cm distal to its insertion point on the GSV. The transected vein was anastomosed end-to-side to the GSV, which was ligated between the tributary insertion site and the anastomosis. Venous valve competence were screened by serial postoperative duplex examination, and venous haemodynamic changes were analyzed using venous filling index (VFI) measured by air plethysmograph pre- and postoperatively. The follow-up period was 5-years. Results Sixty-seven patients were included in whom 76 limbs were treated. There was a statistically significant reduction in the vein diameter at the SFJ after 5-years (0.83 S.D. 0.29 cm to 0.46 S.D. 0.12 cm, p = 0.0002, Wilcoxon). Similarly, significant reduction was found in the GSV at the 5-year follow-up point (0.63 S.D. 0.19 cm to 0.39 S.D. 0.11 cm, p < 0.0001, Wilcoxon). On the other hand, there was significant increase in the diameter of the competent tributary vein postoperatively (0.22 S.D. 0.13 cm to 0.31 S.D. 0.12 cm, p < 0.0001, Wilcoxon). Duplex scanning demonstrated reflux at the SFJ in 12 limbs (16%). Similarly, in the GSV, venous reflux was found in 13 limbs (17%). Reflux in the transposed tributary vein was found in 20 limbs (26%). But only 7 limbs (9%) had minor varicose veins' recurrence. VFI remained normal during the follow-up examination. The preoperative VFI confirmed the presence of venous reflux, but there were significant improvement in the VFI values at all postoperative examinations. Conclusions A-VACT procedure improves venous function, resolves varicose veins at 5-years follow-up as well as preserving the GSV for future grafting.

Adjunctive Catheter-Directed Venous Thrombolysis in Iliofemoral Deep Vein Thrombosis; Short-Term Results from the CaVenT Study, a Multicenter Randomized Controlled Trial

Conventional treatment of acute deep vein thrombosis (DVT) is anticoagulation and compression therapy (Grade 1A recommendations). Following adequate conventional treatment approximately every fourth patient with proximal DVT of the lower limb develop postthrombotic syndrome (PTS). PTS evolves from persistent venous obstruction and/or venous insufficiency caused by inflammatory destruction of the venous valves. Both obstruction and insufficiency of the veins may lead to venous hypertension. Accelerating the removal of venous thrombus by thrombolytic agents is suggested to prevent the development of PTS. Case-series have shown technical and thrombolytic success, however, the ongoing CaVenT Study is the first randomized, controlled trial to evaluate short- and long-term effects of venous catheter-directed thrombolysis (CDT). Our main hypothesis on short-term effects is that CDT in first-time acute DVT increases patency of the affected iliofemoral vein segments after 6 months from <50% on conventional therapy to >80% after adjunctive CDT. From January 2006 to January 2008 103 patients (64 male, mean age 52.1 years) were randomized to receive either adjunctive CDT (n=50) or conventional treatment alone (n=53). After CDT 50–90% lysis (grade II lysis) was achieved in 20 patients, and complete lysis (grade III) in 24 patients. CDT failed in one patient with agenesis of inferior vena cava, and 1 patient was denied CDT because the thrombus did not reach the upper half of the thigh at initiation of the procedure. Non-invasive assessment of the veins performed at 6 months follow-up, included ultrasound with Doppler and air plethysmography. Patients with incompressibility of the femoral vein, no venous flow and/or functional venous obstruction were classified as not having regained iliofemoral venous patency. Patients with duplicate femoral veins with at least one branch with normal compressibility and flow were considered successfully recanalized. Venous insufficiency was defined as reflux lasting >0.5 sec. Patency of the iliofemoral vein segments was found in 32 (64.0%) patients in the CDT group and 19 (35.8%) in the control group, corresponding to a risk difference (RD) of 28.2% (95% CI, 9.7% to 46.7%, p=0.004). Functional venous obstruction was found in 10 (20.0%) patients in the CDT group and in 26 (49.1%) controls, corresponding to a RD of 29.1% (95% CI, 20.0% to 38.0%, p=0.004). There were no significant differences between the groups regarding the other subcategories of patency (absence of iliofemoral flow and incompressibility of femoral vein), other postthrombotic changes of the iliofemoral veins (wall thickening and echoic content of vein lumen), or femoral venous insufficiency. The results indicate that adjunctive CDT increases patency 6 months after iliofemoral DVT, from 36% to 64%. Venous obstruction, but not venous insufficiency was reduced in the CDT group. The clinical relevance of these findings will be assessed when future data from 2 years follow-up are available. Any future documentation of long-term improved functional outcome, i.e., a reduction in PTS, in this patient group will have a significant impact on clinical practice, and may lead to a modification of existing international guidelines.

Pulse Volume Changes Recorded by Air Plethysmography during Single Hemodialysis Sessions

Aims: This study investigated whether fluid removal during a hemodialysis (HD) session affects the results of non-invasive pulse volume recording (PVR) on the lower extremities. Methods:The results of PVR by air plethysmography (Portable Vascular Laboratory; BioMedix, USA) were compared with bioelectrical impedance analysis (Nutriguard-M device; Data Input, Germany) of the human body before and after a single HD in 28 anuric patients (10 women; 18 men) aged 33–76 years. Results:Changes in the wave amplitude of the PVR correlated with the changes in the patient’s weight during HD. Lower stroke volume at the end of HD due to blood volume withdrawal resulted in PVR reduction at the ankle level. Significant Spearman coefficients were found between extracellular water and PVR amplitude changes (r = 0.7, p < 0.01) as well as between intracellular water and PVR (r = 0.6, p < 0.04). Conclusions: To avoid falsification connected with hypervolemia and stroke volume change, the most appropriate time for PVR in vascular diagnosing seems to be the period of a few hours after dialysis session.

Venous Valve Reconstruction in Patients with Secondary Chronic Venous Insufficiency

ObjectivesTo evaluate the durability of venous valve reconstruction (VVR) and its benefits in terms of symptom improvement, ulcer healing and symptom/ulcer recurrence among patients with secondary chronic venous insufficiency (SCVI) in whom superficial venous surgery and compression treatment had failed. MethodsDuring a ten year period (1993–2004) 1800 patients with chronic venous insufficiency (CVI) were evaluated by colour duplex ultrasound (CDU) and ambulatory venous pressure measurement (AVP). Approximately two thirds of patients had SCVI. Initial treatment consisted of compression therapy for a 6 month period. In addition, superficial vein and perforator surgery was performed in those presenting with reflux in these venous systems. 121 patients who did not improve with this treatment were investigated by ascending venography, descending video venography, air plethysmography and measurement of post-ischaemic venous pressure gradient. Thirty two cases having venous reflux without obstruction were selected for VVR. ResultsThe ulcer healing rate within three months was 68% (13/19 patients). VVR resulted in valvular competence and a clinical success rate of 47% and 40% after 3 and 7 years respectively. In 8/13 (54%) of patients with a healed leg ulcer, a median post-operative AVP reduction of 33mmHg (range 20–38) was recorded. The durability of clinical success was numerically longer in patients with haemodynamic improvement (n=10) median 24 months (12–108), when compared with that in those without haemodynamic improvement (n=22) median 18 months (6–108). Popliteal vein reconstruction was part of the VVR procedure in all patients with haemodynamic improvement (post-op. AVP reduction ≥20mmHg). VVR at the popliteal level alone or combined with inguinal reconstruction seemed to be the one significant factor associated with haemodynamic improvement (P=0.014, Chi squared). ConclusionVVR may lead to ulcer healing, but when performed at the popliteal level, haemodynamic improvement can be obtained along with a longer recurrence-free period (durability). VVR should be considered in the treatment of patients with SCVI who do not respond to superficial venous surgery and compression treatment.

Mechanical Inhibition of Angiogenesis at the Saphenofemoral Junction in the Surgical Treatment of Varicose Veins

Saphenofemoral junction (SFJ) ligation has been a major component of surgical intervention for varicose veins; however, recurrence occurs in as many as 40%. Neovascularization with reconnection of the venous channels at the transected SFJ has been identified as the major cause of this recurrence. This randomized controlled study sought to evaluate mechanical suppression of neovascularization at the SFJ, with the use of a synthetic patch, to prevent recurrence after ligation surgery. A total of 389 limbs (from 292 patients) were randomized into either control (SFJ ligation surgery) or patch (SFJ ligation with polytetrafluoroethylene patch of the transected SFJ) groups. All patients underwent clinical assessment, duplex imaging, and air plethysmography studies preoperatively and at 1, 6, 12, and 36 months postoperatively. The patch consistently halved the recurrence rate to 3 years postoperatively in all clinical subgroups. In those patched SFJs that still developed recurrence, evidence of neovascularization circumventing the polytetrafluoroethylene patch was observed by both ultrasound and histology. This study demonstrates that use of a polytetrafluoroethylene patch is an effective mechanical suppressant of neovasculogenesis at the SFJ and can be safely used as a strategy to improve long-term outcome of varicose vein surgery.

Correlation of haemodynamics and ankle mobility with clinical classes of clinical, aetiological, anatomical and pathological classification in venous disease

To correlate venous haemodynamic parameters of lower limbs and amplitude of ankle mobility with the clinical, aetiological, anatomical and pathological classification (CEAP) for venous disease. Two hundred and eighty-four lower limbs of 142 Caucasian women were evaluated and distributed in six groups according to the CEAP classification: Group I = C0 and C1 (n = 24); Group II = C2 (n = 30); Group III = C3 (n = 27); Group IV = C4 (n = 23); Group V = C5 (n = 20) and Group VI = C6 (n = 18). Goniometric examinations of ankle joints and air plethysmography (APG) were performed. Analysis of variance and the Bonferroni correction, Kruskal-Wallis' non-parametric and Dunn tests were utilized for statistical analysis with the level of significance being set at 5% (P value < 0.05). There were significant restrictions in ankle mobility seen by goniometry at the C5 stage. In addition, significant changes in the venous-filling index were identified at C2, changes in the ejection fraction at C4 and changes in the residual volume fraction at the C4 stage. The evolution of the clinical state of ankles affected by venous diseases is correlated to a reduction of joint mobility and haemodynamic alterations identified using APG.

Tracking Body Composition Changes Over Time: Comparison of Methods

Tracking changes in body composition (BC) is critical for observational and intervention studies. Little is known about the best approaches to tracking BC changes. PURPOSE: To compare air plethysmography (AP) and bioelectrical impedance (BI) estimates of BC in a group of college students, some who lose and some who gain body mass (BM). METHODS: 66 college students (26 males, 40 females, 18.1 y) were measured at the beginning and end of their first year at college. AP and BI were used to estimate fat mass (FM), fat-free mass (FFM), and body fat percentage (%BF). BI also assessed kg of trunk fat. BM, body mass index (BMI), and waist circumference (WC) were measured using standard procedures. Repeated measures ANOVA determined whether AP and BI yielded similar results. Bivariate correlation and multiple regression determined which variables were related to changes in BM, BMI and WC. RESULTS: There was wide variation in BC change, but the majority of individuals gained in BM, WC, and FM. On average, subjects gained 1.6±2.9 kg in BM, 1.24±3.02 cm in WC, and 0.35±1.03 kg/m2 in BMI. %BF increased by 0.64±3.42 and 1.37±2.76% according to AP and BI, respectively. AP yielded higher estimates of %BF than BI (24.0 ± 10.5% vs. 22.8 ± 8.6%, p=0.029). The change in FM estimated from AP was highly and significantly (p<0.01) related to change in BM (r=0.81), BMI (r=0.77), and WC (r=0.61). Change in FM estimated from AP was a stronger predictor of change in WC, BMI, and BM than the AP-derived change in FFM or %BF or any of the variables estimated by BI. CONCLUSION: AP and BI both reflect an increase in FM over time in college students. However, differences in estimates from the 2 methods do not allow them to be used interchangeably. The changes in FM according to AP are most reflective of the changes in BM, BMI, and WC.

Reversal of Lower Limb Edema by Calf Muscle Pump Stimulation

Peripheral edema (PE) is commonly coupled with heart failure, restrictive cardiomyopathy, nephrotic syndrome, renal failure, and hypoproteinemia. Diuretics and/or limb elevation, although commonly prescribed to treat PE, are often insufficient to remove sufficient fluid to prevent complications. We assessed the ability of the calf muscle pump (CMP) stimulation to reverse PE. Fluid volume was evaluated by air plethysmography in the right legs of 54 adult women (mean age 46.7 +/- 1.5 years) following venous status assessment. Change in calf volume was assessed during 30 minutes of quiet sitting, followed by 30 minutes of sitting with CMP stimulation via micromechanical stimulation of the plantar surface. Leg volume changes demonstrated a bimodal distribution. Leg volume decreased during quiet sitting in 56% of the study group, whereas in 44% of the group, significant lower leg fluid pooling was evident (increase in calf volume of 14.0 +/- 0.3 mL/h). CMP stimulation reversed the fluid pooling in the edematous group (-2.7 +/- 0.1 mL/h) and was able to accelerate fluid removal in the nonedematous group. Approximately two fifths of adult women experience substantial pooling when their lower limbs are maintained in a dependent position. Lower-extremity edema exhibited by these women may primarily be due to inadequate calf muscle tone because exogenous stimulation of the CMP was sufficient to halt and reverse fluid pooling. Whether CMP stimulation would provide a means to treat PE in individuals with edema-related health complications, such as congestive heart failure, merits further investigation.

Characteristics Of 1st Year College Females: Weight Gainers vs Weight Losers

PURPOSE: Anecdotal evidence suggests that during the 1st year of college significant weight gain occurs. This is sometimes referred to as the "freshman fifteen." Several studies however, have reported contradictory results, particularly in reference to females. The purpose of this study is to determine dietary (D) and physical activity (PA) characteristics of 1st year college females who either gained or lost weight during the 1st semester of their college experience. METHODS: Forty females (age=18.1 ±0.34 years) volunteered to participate. Weight (W) and height were measured to calculate BMI. Body composition (%Fat) was assessed with air plethysmography. D was assessed with a 3-d food and activity diary and was processed by the Dietary Research Center at CCHMC. PA was assessed by 7 consecutive days of accelerometry wear. All measurements were taken in September (T1) and approximately 20 weeks later (T2). RESULTS: Dependent t-tests indicated non-significant changes from Time 1 to Time 2 in W, %Fat, D and PA for the overall group, however large deviations and ranges for the change scores indicated considerable inter-individual variability. 31 Ss either gained (N=16) W and %Fat, or lost (N=15) W and %Fat from T1 to T2. The mean W and %Fat gain was 1.8 ± 1.4 kg and 2.4 ± 2.3%, respectively. Mean W and %Fat loss was 2.1 ± 3 kg and 2.4 ± 2.7%, respectively. Independent t-tests conducted to compare the gainers and losers revealed that those who gained W and %Fat showed significantly greater increases in total intake of Kcal, carbohydrate, protein, and calcium from T1 to T2 than did those who lost W and %Fat. No significant differences in PA were found between the gainers and losers. CONCLUSIONS: Analysis of the overall mean data suggests that W and %Fat did not change over the course of a semester in these particular females, however, after further inspection of the data an almost equal number of Ss either gained or lost W and %Fat. Intake of commercially available coffees and soda beverages were identified as significant contributors to the increase in total Kcal, carbohydrate, protein, and calcium intake of the W and %Fat gainers as compared to the losers.

Mechanisms of changes in human hemodynamics under the conditions of microgravity and prognosis of postflight orthostatic stability

The mechanisms of hemodynamic responses to orthostatic stresses and orthostatic stability (OS) of cosmonauts were studied before and after short-and long-term spaceflights (SFs) using orthostatic tests, as well as before, during, and after SFs using ultrasonic methods in tests with exposure to lower body negative pressure (LBNP). The capacitance and distensibility of the veins of the lower extremities were studied using occlusive air plethysmography before, during, and after SFs of different durations. A stay in microgravity has been proved to result in detraining of, mainly, the vascular mechanisms of compensating orthostatic perturbations. It has been established that the decrease in OS under the influence of microgravity is determined by a reduction of the vasoconstrictive ability of large blood vessels of the lower extremities; an increase in venous distensibility and capacitance of the legs; and an impairment of blood flow regulation, which leads to a cerebral blood flow deficit in orthostatic stresses, and of the initial individual OS before the flight. The results of preflight studies of hemodynamics by ultrasonic methods at LBNP and the data of orthostatic tests before SFs make it possible to predict the degree of decrease of OS after an SF proceeding in the normal mode. At the same time, the data of ultrasonic blood flow examination provide more a accurate estimation of OS and make it possible to assess the physiological reserves of hemodynamic regulation and to reveal the loss of regulation capacity even in cases where integrated indices (heart rate and blood pressure) are within the normal ranges.

IAAT, Catecholamines, and Parity in African-American and European-American Women

We have recently reported that parous European-American (EA) women have disproportionately more intra-abdominal adipose tissue (IAAT) than their nulliparous counterparts. Mediating mechanisms for IAAT accumulation remain unknown; however, some evidence suggests a possible catecholamine link. The objective of this study was to determine whether the IAAT-parity relationship found in EA women exists in African-American (AA) women and to determine whether catecholamines play a mediating role. Subjects included 44 EA and 47 AA premenopausal women. Free-living physical activity by doubly labeled water (activity-related time equivalent (ARTE)), body composition (air plethysmography, computed tomography), and 24-h fractionated urinary catecholamines were measured. Repeated measures ANOVA revealed parous EA and AA women had significantly higher IAAT than their nulliparous counterparts (100.1 +/- 28.5 and 76.2 +/- 34.8 cm(2) vs. 75.9 +/- 29.1 and 59.6 +/- 15.0 cm(2)). In AA women and nulliparous women, 24-h urinary dopamine was significantly higher (AA parous 260.8 +/- 88; EA parous 197.2 +/- 78.8; AA nulliparous 376.5 +/- 81; EA nulliparous 289.6 +/- 62). Multiple regression analysis for modeling IAAT indicated that race, parity, dopamine, ARTE, and VO(2max) were all significant and independent contributors to the model (Unstandardized betas: race -32.6 +/- 7.4; parity (number of births) 10.0 +/- 3.4; 24-h urinary dopamine 0.08 +/- 0.04; ARTE (min/day) -0.09 +/- 0.04; VO(2max) (ml/kg/min) -2.8 +/- 1.0). Independent of the potential confounders: age, race, percent body fat, IAAT, 24-h fractionated urinary catecholamines, physical activity, and VO(2max), parous EA and AA women had more IAAT than their nulliparous counterparts. Of the catecholamines, dopamine was found to be significantly lower in parous women and higher in AA's. Dopamine, however, did not explain racial or parity differences in IAAT.

Obesity and Impaired Venous Function

The clinical severity of venous disease is often worse in obese patients. The objectives of this study were to compare lower limb venous physiology assessed by air plethysmography in a large group of obese and normal-weight patients; to consider the effect of posture on these measures and on foot vein pressure in a smaller cohort. Venous function was assessed using air plethysmography and duplex scanning in 934 consecutive patients presenting for assessment of venous disease. These were grouped into obese or non-obese categories. A smaller group of twenty patients with a range of body weights were randomly selected from a database of patients with varicose veins. Foot vein pressures and femoral vein diameter were measured standing, sitting, lying and ambulating. Venous disease was more clinically severe in the obese limbs (CEAP C5&6 non-obese group 20.5%, obese group 35.4%, p<0.001 chi(2)). Venous reflux was worse in the obese but measures of muscle pump function were better. Residual volumes and fractions were better in the obese (mean residual volume, non-obese 60 SD 36, obese 50 SD 42, p<0.001 t test). In the smaller study group weight correlated with the diameter of the superficial femoral vein (r=0.50), ambulatory venous pressure (r=0.45), venous filling index (r=0.49) and the ejection volume (r=0.38, p<0.05). The foot venous pressure was significantly greater in the obese in all positions. The CEAP clinical stage of venous disease is more advanced in obese patients than non-obese patients with comparable anatomical patterns of venous incompetence. This may be the result of raised intra-abdominal pressure reported in previous studies, leading to greater reflux, increased vein diameter and venous pressures.

The Tromped: A Solution for Flight-Related Deep Vein Thrombosis?

Flight-related deep vein thrombosis (DVT) is well recognized. Reduced venous return occurs during immobility. This alteration in venous hemodynamics may contribute to DVT development. A prototype design of an in-flight exercise device to stimulate ambulatory bloodflow while seated has been developed, consisting of a foot pedal attached to a base by a hinge mechanism. Four devices of differing resistance were evaluated. Calf muscle pump function was assessed by air plethysmography in 10 healthy volunteers. Ejection volume fraction and RVF were determined in the standing position (control values) and were compared with those achieved by depression of the 4 devices while seated. Similar EVF and RVF values were achieved by the control and 2 of the devices. Plantar flexion against a predetermined resistance can effectively activate the calf muscle pump while seated and may reduce the incidence of flight-related DVT.

Reduced Defense of Central Blood Volume During Acute Lower Body Negative Pressure–Induced Hypovolemic Circulatory Stress in Aging Women

Elderly humans are more vulnerable to trauma and hemorrhage than young and elderly men and respond with decreased defense of central blood volume during acute experimental hypovolemia induced by lower body negative pressure (LBNP). However, these defense mechanisms have not been evaluated in elderly women. The aim of this study was to determine the effectiveness of compensatory responses to defend central blood volume during experimental hypovolemia in elderly and young women. Cardiovascular responses in 34 women, 12 elderly (66 ± 1 years) and 22 young women (23 ± 0.4 years), were studied during experimental hypovolemia induced by LBNP of 11 to 44 mmHg. Air plethysmography was used to assess the capacitance response (redistribution of peripheral venous blood to the central circulation) as well as net capillary fluid transfer from tissue to blood in the arm. Lower body negative pressure seemed to create comparable hypovolemia measured as total calf volume increase in elderly and young women. Heart rate increased less in elderly women (LBNP of 44 mmHg: 20 ± 2 vs. 37 ± 4%; P < 0.01) but with similar (%) increase in forearm vascular resistance. Mobilization of capacitance blood from the peripheral circulation was both slower and decreased by ∼60% in elderly women (P < 0.001), and net capillary fluid absorption from surrounding tissues was reduced by ∼40% (P < 0.01, LBNP of 44 mmHg). Elderly women responded with less increase in heart rate but with equal forearm vascular resistance (%) response during LBNP. Furthermore, the compensatory capacitance response was both slower and substantially decreased, and net capillary fluid absorption considerably reduced, collectively indicating less efficiency to defend central blood volume in elderly than in young women.

A variabilidade hemodinâmica venosa detectada pelos parâmetros da pletismografia a ar nas classes clínicas da classificação CEAP

CONTEXTO: A variabilidade hemodinâmica da pletismografia a ar é conhecida, mas o exato papel dessa variabilidade no cotidiano clínico não foi investigado, podendo ter algum significado clínico ainda não explorado. Sabe-se que há sobreposição entre as classes clínicas (C0 a C6) da classificação CEAP e mesmo entre membros inferiores de uma mesma classe clínica. OBJETIVO: Avaliar a variabilidade hemodinâmica dos parâmetros da pletismografia a ar nas classes clínicas da classificação CEAP. MÉTODO: Este estudo retrospectivo confronta a doença varicosa de membros inferiores classificada de C0 a C6 pela classificação CEAP com os parâmetros hemodinâmicos venosos obtidos pela pletismografia a ar. Os dados obtidos foram tabulados e analisados em suas classes clínicas pelos testes de variância de Kruskal-Wallys e Barllett. RESULTADOS: Foram realizados 310 exames em 230 pacientes cujas idades variaram entre 19 a 81 anos, com uma média de 46,2 anos. Os parâmetros índice de enchimento venoso e volume venoso funcional mostraram aumento da variabilidade hemodinâmica quando analisados na classe clínica C0 do CEAP, demonstrada por meio do coeficiente de variabilidade que, para o índice de enchimento venoso foi de 28,12% na classe clínica C0 e se manteve acima de 57% nas classes de C2 a C6. A fração de ejeção e a fração de volume residual não aumentaram a variabilidade quando comparados com a classe clínica C0 do CEAP. CONCLUSÃO: O índice de enchimento venoso foi o melhor parâmetro para avaliação e triagem de pacientes com insuficiência venosa crônica, mas tem grande variabilidade nas classes clínicas C2 a C6 do CEAP.

Métodos de diagnóstico não-invasivos para avaliação da insuficiência venosa dos membros inferiores

A avaliação clínica dos membros inferiores na insuficiência venosa por si só não identifica os sistemas envolvidos ou os níveis anatômicos, sendo necessários exames complementares. Esses exames podem ser invasivos ou não-invasivos. Os invasivos, como flebografia e pressão venosa ambulatória, apesar de terem boa acurácia, trazem desconforto e complicações. Dentre os não-invasivos, destacam-se: Doppler ultra-som de ondas contínuas, fotopletismografia, pletismografia a ar e mapeamento dúplex. O Doppler ultra-som avalia a velocidade do fluxo sangüíneo de maneira indireta. A fotopletismografia avalia o tempo de reenchimento venoso, fornecendo um parâmetro objetivo de quantificação do refluxo venoso. A pletismografia a ar permite quantificar a redução ou não da capacitância, o refluxo e o desempenho da bomba muscular da panturrilha. O dúplex é considerado padrão-ouro dentre os não-invasivos, porque permite uma avaliação quantitativa e qualitativa, fornecendo informações anatômicas e funcionais, dando avaliação mais completa e detalhada dos sistemas venosos profundo e superficial.