Enhancing venous outflow in the lower limb with intermittent pneumatic compression. A comparative haemodynamic analysis on the effect of foot vs. calf vs. foot and calf compression

Nephrotic Syndrome – Different Risk of Venous Thromboembolism with Different Approaches to Justify Prophylactic Anticoagulation

All of the circumstances influencing any of the elements of Virchow’s Triad can increase the risk of venous thromboembolism. Assessing prothrombotic factors can sometimes be difficult. One of the examples of such a condition is nephrotic syndrome. In this condition at least two elements of Virchow’s triad are affected: physiological blood composition and the venous blood flow which is slowed down by the edema. Except for the cases mentioned in KDIGO (Kidney Disease: Improving Global Outcomes), the use of anticoagulant drugs in the prophylaxis of VTE (Venous Thromboembolism) in nephrotic syndrome seems unclear. Nevertheless, due to the increased risk of VTE, it is worth implementing mechanical anticoagulant prophylaxis, which can also improve the quality of life of patients by reducing swelling. The article analyzes the current knowledge on the field and gives some proposals with low bleeding risk.

Intermittent pneumatic compression for prolonged standing workers with leg edema and pain

Even healthy individuals often encounter leg venous symptoms such as heaviness, pain, and swelling especially after prolonged standing work. Intermittent pneumatic compression (IPC) is a widely used simple therapy for preventing deep vein thrombosis and for treating lymphedema and chronic venous insufficiency. However, IPC has not been evaluated for its effect in relieving venous symptoms of healthy people.This was single center, cross-over study to investigate the effect of IPC for 20 healthy volunteers who usually stand on duty and complain of leg pain and swelling. The primary outcome was pain (measured using a visual analogue scale) and secondary outcomes were leg circumference and volume. Three different interventions included natural rest, sequential mode of IPC, and circular mode of IPC. Outcomes were measured before work and immediately after work (T1), after 30 minutes of intervention (T2), and 30 minutes of rest after intervention (T3).Pain and leg circumferences were significantly improved at T2 and T3 compared with those at T1. Sequential and circular IPC led to significantly greater improvement in pain and leg circumferences than just natural rest, but there was no difference in its effect according to the 2 modes of IPC. Leg volume was reduced significantly at T2 and T3 as compared with T1 in all 3 interventions, but effects did not differ among 3 intervention groups.IPC is effective for reducing leg pain and circumferences more than natural rest in healthy adults with prolonged standing work, without causing adverse events.

Intermittent compression induces transitory hypoxic stimuli, upstream vasodilation and enhanced perfusion of skin capillaries, independent of age and diabetes

The benefit of enhanced shear stress to the vascular endothelium has been well-documented in conduit arteries but is less understood in skin microcirculation. The aim of this study was to provide physiological evidence of the vascular changes in skin microcirculation induced by intermittent pneumatic compression (IPC) of 1 s cuff inflation (130 mmHg) every 20 s to the palm of the hand for 30 min. The oxygenation and hemodynamics of dorsal mid-phalangeal finger skin microcirculation were assessed by laser Doppler fluximetry and reflectance spectroscopy before, during, and after IPC in 15 young (18-39 years old) and 39 older (40-80 years old) controls and 32 older subjects with type 2 diabetes mellitus. Each individual cuff inflation induced: 1) brief surge in flux immediately after cuff deflation followed by 2) transitory reduction in blood oxygen for ∼4 s, and 3) a second increase in perfusion and oxygenation of the microcirculation peaking ∼11 s after cuff deflation in all subject groups. With no significant change in blood volume observed by reflectance spectroscopy, despite the increased shear stress at the observed site, this second peak in flux and blood oxygen suggests a delayed vasoactive response upstream inducing increased arterial influx in the microcirculation that was higher in older controls and subjects with diabetes compared to young controls (P < 0.001, P < 0.001, respectively) and achieving maximum capillary recruitment in all subject groups. Transitory hypoxic stimuli with conducted vasodilation may be a mechanism through which IPC enhances capillary perfusion in skin microcirculation independent of age and type 2 diabetes mellitus.NEW & NOTEWORTHY This study demonstrates that hand intermittent pneumatic compression evokes transitory hypoxic stimuli in distal finger skin microcirculation inducing vasodilation of arterial inflow vessels, enhanced perfusion, and maximum capillary recruitment in young and older subjects and older subjects with type 2 diabetes mellitus. Enhanced shear stress in the microcirculation did not appear to induce local skin vasodilation.

A randomised controlled trial of neuromuscular stimulation in non-operative venous disease improves clinical and symptomatic status

BACKGROUND

This randomised controlled trial investigates the dosing effect of neuromuscular electrical stimulation (NMES) in patients with chronic venous disease (CVD).

METHODS

Seventy-six patients with CEAP C3-C5 were randomised to Group A (no NMES), B (30 minutes of NMES daily) or C (60 minutes of NMES daily). Primary outcome was percentage change in Femoral Vein Time Averaged Mean Velocity (TAMV) at 6 weeks. Clinical severity scores, disease-specific and generic quality of life (QoL) were assessed.

RESULTS

Seventy-six patients were recruited - mean age 60.8 (SD14.4) and 47:29 male. Six patients lost to follow-up. Percentage change in TAMV (p<0.001) was significantly increased in Groups B and C. Aberdeen Varicose Veins Questionnaire Score (-6.9, p=0.029) and Venous Clinical Severity Score (-4, p-0.003) improved in Group C, and worsened in Group A (+1, p=0.025).

CONCLUSIONS

Daily NMES usage increases flow parameters, with twice daily usage improving QoL and clinical severity at 6 weeks in CVD patients.

Hemodynamic regulation of perivalvular endothelial gene expression prevents deep venous thrombosis

Deep venous thrombosis (DVT) and secondary pulmonary embolism cause approximately 100,000 deaths per year in the United States. Physical immobility is the most significant risk factor for DVT, but a molecular and cellular basis for this link has not been defined. We found that the endothelial cells surrounding the venous valve, where DVTs originate, express high levels of FOXC2 and PROX1, transcription factors known to be activated by oscillatory shear stress. The perivalvular venous endothelial cells exhibited a powerful antithrombotic phenotype characterized by low levels of the prothrombotic proteins vWF, P-selectin, and ICAM1 and high levels of the antithrombotic proteins thrombomodulin (THBD), endothelial protein C receptor (EPCR), and tissue factor pathway inhibitor (TFPI). The perivalvular antithrombotic phenotype was lost following genetic deletion of FOXC2 or femoral artery ligation to reduce venous flow in mice, and at the site of origin of human DVT associated with fatal pulmonary embolism. Oscillatory blood flow was detected at perivalvular sites in human veins following muscular activity, but not in the immobile state or after activation of an intermittent compression device designed to prevent DVT. These findings support a mechanism of DVT pathogenesis in which loss of muscular activity results in loss of oscillatory shear-dependent transcriptional and antithrombotic phenotypes in perivalvular venous endothelial cells, and suggest that prevention of DVT and pulmonary embolism may be improved by mechanical devices specifically designed to restore perivalvular oscillatory flow.

Hyperelastic Properties of Platinum Cured Silicones and its Applications in Active Compression

This paper presents the fundamental research of design, development, and evaluation of an active compression system consisting of silicone based inflatable mini-bladders, which could be used in applying radial pressure for the treatment of venous disease. The use of mini-bladders will nullify the effect of radius of curvature and provide a higher resolution to the pressure distribution. They are designed with two elastomeric layers and inflation is limited only to one side. The mini-bladders apply a radial force onto the treated surface when inflated, and the pressure inside mini-bladders could be measured using the concept of back pressure, which provides the flexibility to inflate mini-bladders to a predefined pressure. The 3-D deformation profile of the mini-bladders was analysed using finite element method (FEM) and FEM simulations were validated with experimental data, which showed good agreement within pressure region required for the treatment of venous disease. Finally, the pressure transmission characteristics of mini-bladders were evaluated on a biofidellic lower leg surrogate and the results have shown that the mini-bladders could apply a uniform pressure irrespective of the location on the leg with a 60%–70% of inlet pressure successfully transmitted onto the leg surface, while 40%–50% was available after the fat layers.

Effects of Intermittent Pneumatic Compression on Leg Vascular Function in People with Spinal Cord Injury: A Pilot Study

Objective: The purpose of this pilot study was to determine whether 60 mins of intermittent pneumatic compression therapy (IPC) could acutely increase leg blood flow-induced shear stress and enhance vascular endothelial function in persons with spinal cord injury (SCI). Design: Pretest with multiple posttests, within subject randomized control design. Setting: University of Southern Mississippi, Spinal Cord Injury Research Program within the School of Kinesiology, recruiting from the local community in Hattiesburg, Jackson, and Gulfport, MS. Participants: Eight adults with SCI (injury level: T3 and below; ASIA class A-C; age: 41±17 yrs). Interventions: A 60-min IPC session was performed in one leg (experimental leg; EXP), with the other leg serving as a control (CON). Outcomes Measures: Posterior-tibial artery shear rate (Doppler-ultrasound) was examined at rest, and at 15 and 45 mins during IPC. Endothelial function was assessed using the flow-mediated dilation (FMD) technique, before and after IPC. Results: Resting FMD (mm) was similar between legs at rest. A two-way repeated measures ANOVA (leg x time) revealed that during IPC, peak shear rate increased in the EXP leg (215±137 to 285±164 s^-1 at 15 mins; +39±29%, P = 0.03), with no change occurring in the CON. In addition, FMD significantly increased in the EXP leg (Pre IPC: 0.36±0.14 vs. Post IPC: 0.47±0.17 mm; P = 0.011, d = 0.66), with no change occurring in the CON leg. Conclusion: These preliminary findings suggests that IPC therapy may acutely increase leg shear stress within 15 mins, with a resultant moderate-large improvement in vascular endothelial function after 60 mins in people with SCI.

[Alternating pneumocompression - effective physiotherapeutic method for the prevention of venous thromboembolic complications in patients of medium and high risk in the acute period of the stroke]

BACKGROUND

the patients presenting with severe post-stroke in the acute period of this condition are characterized by the high risk of venous thromboembolic complications (VTEC), with the most dangerous of them being pulmonary embolism that makes an appreciable contribution to the mortality rate of such patients at the hospital stage of their treatment. Among the physical methods for the prevention of VTE, such as wearing graduated compression stockings (GCS), myoelectrostimulation (MES), pneumatic intermittent compression (PIC), only the latter technique has been shown to be efficient when applied for the treatment of surgical patients during the post-stroke period with the level of evidence 2B and the very uncertain parameters of the impact.

AIM

The objective of the present study was to evaluate the advantages of the PIC in comparison with that of GCS and MES, substantiate the choice of the former method for the management of the high-risk post-stroke patients, and determine the impact parameters of PIC during the peracute and acute periods of the disease.

MATERIAL AND METHODS

We conducted a series of analyses of the results of several controlled randomized studies and relevant reviews of the literature with a view to determining the feasibility and effectiveness of application of one or another approach and clarifying the parameters of the exposure to GCS, MES, and PIC for the prevention of VTEC.

RESULTS AND DISCUSSION

The results of these studies gave evidence that the effectiveness of the GCS and MES is insufficient in contrast to that of PIC that was found to decrease the relative risk of deep vein thrombosis (DVT) by 62% compared with placebo and by 47% in comparison with GCS. The low risk of DVT associated with the application of PIC was apparent from the low OR value of 0.45 and the absolute reduction in the risk of DVT by 3.6%. The analysis of the parameters being used made it possible to identify side effects and thereby allowed to formulate the optimal method for the application of PIC for the purpose of prevention of VTEC in the post-stroke patients during the peracute and acute periods of the disease.

CONCLUSION

Only PIC of all the currently available methods for the physical prevention of VTEC in the group of high risk post-stroke patients during the peracute and acute periods of this condition can be practiced in the reliable evidence-based manner. The most rational PIC modality consists of exerting the external pressure on the lower extremities within the first 12-24 hours after stroke with the use of the cuffs of the «lower leg» type (i.e. at a pressure of 40-50 mm Hg in the wave mode with memorization for the multi-sectional cuffs, daily in the continuous manner throughout the daytime till the patient is downgraded to the group at lower risk of VTEC or actually till the discharge from the hospital.

Efficacy and safety of a new pneumatic compression device for peripheral arterial disease with intermittent claudication

Background: The primary objective of the study was to demonstrate that Intermittent Pneumatic Compression (IPC) with the new ANGIO PRESS™ IPC device can significantly improve the walking distance, i.e. pain free initial intermittent claudication distance (ICD) and the absolute claudication distance (ACD) in patients with stage II peripheral arterial occlusive disease (PAD) compared to control treatment.

Patients and methods: A total of 67 patients were screened and randomized into the study in four clinical centers based in Israel and Germany. Patients were randomized to one of the two study groups: 1. Medication treatment with ASS / Clopidogrel and standardized walking exercise with additional IPC treatment, two times per day for 1.5 hours for three months. 2. Medication treatment and standardized walking exercise alone. The safety and efficacy of the ANGIO PRESS™ device was determined for the treatment of symptoms of PAD Fontaine stage IIb by measuring the pain free walking distance, the absolute walking distance, the ankle-brachial-index (ABI) and the walking pain. Additionally the quality of life (QOL) of each subject was assessed according to the SF-36 questionnaire. Subjects were followed up at six weeks and 3 months.

Results: No statistical differences were observed in any of the demographic characteristics and baseline scores. A significant difference was found between the treatment and control group in the ACD and the walking pain scale. Subjects in the treatment group improved their total walking distance in 54 meters, an improvement of 40% compared to their baseline distance. The walking pain improved by 1.89 points in the treatment group. Despite the fact that the difference in the ICD between the study groups were not found significantly different, the mean change from baseline in ICD score at the three month visit in the treatment group of 37 m was found statistically significant (p=0.0002), whereas the mean change of 20.7 m in the control group was not found significantly different. No changes were found between the study groups in the ABI and the QOL. The treatment was easy to tolerate and most patients suffered no side-effects, nor complained of any significant discomfort. Two subjects suffered from SAEs which were determined as not related to the study treatment.

Conclusion: The ANGIO PRESS™ is a non-invasive, easy to use, home treatment which is safe and moderately effective for the treatment of intermittent claudication. The ability of subjects to improve their absolute walking distance and reduce the walking pain on the same time may offer a significant value for patients at early stages of PAD who are not indicated for an invasive treatment.

Venous Hemodynamics After Total Hip Arthroplasty: A Comparison Between Portable vs Stationary Pneumatic Compression Devices and the Effect of Body Position

BACKGROUND

Improvements in device design have allowed for portable pneumatic compression devices (PPCDs). However, portability results in smaller pumps that move less blood. Additionally, although patients often stand when wearing PPCDs, few studies have evaluated the hemodynamic effects of PCDs while standing.

METHODS

A crossover study was performed to compare a PPCD (ActiveCare+S.F.T.; Medical Compression Systems, Or Akiva, Israel) to a stationary pneumatic compression device (SPCD) (VenaFlow; DJO Global, Carlsbad, CA) on hemodynamics in supine and standing positions among 2 cohorts composed of 10 controls and 10 total hip arthroplasty patients. Differences in baseline peak venous velocity (PVV), PVV with each PCD, and delta PVV with each PCD were assessed. A multivariate analysis was performed to examine differences between cohorts, devices, and position.

RESULTS

In both positions, the SPCD demonstrated a larger change in PVV when compared to the PPCD (P < .001). The total hip arthroplasty group had a greater delta PVV while standing when considering both PCDs together (P < .001). When considering both cohorts, delta PVV was greater while standing, only when the SPCD was used (P < .001). There was no difference between standing and supine positions when the PPCD was used.

CONCLUSION

The SPCD demonstrated a greater capacity to increase PPV in the supine and standing positions. The SPCD generated greater values of PVV and delta PVV in the standing position. Although these results demonstrate a difference between devices, it is important to establish the PVV necessary to prevent VTE before one is considered more effective.

Evaluating the efficacy of an active compression brace on orthostatic cardiovascular responses

Orthostatic intolerance, one of the principle causes of syncope, can occur secondary to concomitant venous pooling and enhanced capillary filtration. We aimed to evaluate a prototype portable calf active compression brace (ACB) designed to improve orthostatic haemodynamic control. Fourteen healthy volunteers participated in a randomized, placebo controlled, cross-over, double-blind study. Testing consisted of head-upright tilting and walking on a treadmill conducted on two consecutive days with a pair of ACBs wrapped around both calves. The ACB was actuated on one test day, but not on the other (placebo). Wearability, comfort, and ambulatory use of the ACB were assessed using questionnaires. The average calf pressure exerted by the ACB was 46.3±2.2 mmHg and the actuation pressure was 20.7±1.7 mmHg. When considering the differences between ACB actuation and placebo during tilt after supine rest there were trends for a larger stroke volume (+5.20±2.34%, p = 0.05) and lower heart rate (-5.12±2.41%, p = 0.06) with ACB actuation, with no effect on systolic arterial pressure (+4.86±3.41%, p = 0.18). The decrease in stroke volume after ten minutes of tilting was positively correlated with the height:calf circumference (r = 0.464; p = 0.029; n = 22; both conditions combined). The increase in heart rate after ten minutes of tilting was negatively correlated with the height:calf circumference (r = -0.485; p = 0.022; n = 22; both conditions combined) and was positively correlated with the average calf circumference (r = 0.539; p = 0.009; n = 22; both conditions combined). Participants reported good ACB wearability and comfort during ambulatory use. These data verify that the ACB increased stroke volume during tilting in healthy controls. Active calf compression garments may be a viable option for the management of orthostatic intolerance.

A Shape Memory Alloy-Based Compression Therapy Prototype Tested With Individuals in Seated Position

Orthostatic intolerance in patients can occur secondary to concomitant venous pooling and enhanced capillary filtration when standing upright, and is one of the principle causes of syncope or fainting. Compression therapy is commonly recommended for the management of syncope based on the assumption that it increases venous return. Technologies currently used include compression stockings, whose efficacy has, however, been challenged, and intermittent pneumatic pressure devices, which highly restrict the patients' mobility. This paper therefore investigates a novel active compression brace (ACB), which could potentially provide intermittent pressure while not restricting movements. The ACB, actuated by shape memory alloy (SMA) wires, in this work was tested with twelve healthy individuals in a seated position. The experimental observation showed that the ACB can apply a constant initial pressure to the leg similar to commercial compression stockings and also produce intermittent pressure exceeding 30 mmHg. A comparison between analytical and experimental results showed a maximum of 2.08 mmHg absolute averaged difference among all the participants. A correlation analysis showed that the normalized root-mean-square deviation (NRMSD) between the experimental and analytical results had a significant negative correlation with the estimated total calf circumference minus the calf fat cross-sectional area (CSA). A calibration formula, accounting for fat and circumference of the leg, was introduced to account for these two parameters. The comfort of the ACB was also compared to two other available compression devices using questionnaires. No participants reported discomfort in terms of pressure, skin irritation, or heat generated by the ACB.

Design and Characterization of a Soft Robotic Therapeutic Glove for Rheumatoid Arthritis

The modeling and experimentation of a pneumatic actuation system for the development of a soft robotic therapeutic glove is proposed in this article for the prevention of finger deformities in rheumatoid arthritis (RA) patients. The Rehabilitative Arthritis Glove (RA-Glove) is a soft robotic glove fitted with two internal inflatable actuators for lateral compression and massage of the fingers and their joints. Two mechanical models to predict the indentation and bending characteristics of the inflatable actuators based on their geometrical parameters will be presented and validated with experimental results. Experimental validation shows that the model was within a standard deviation of the experimental mean for input pressure range of 0 to 2 bars. Evaluation of the RA-Glove was also performed on six healthy human subjects. The stress distribution along the fingers of the subjects using the RA-Glove was also shown to be even and specific to the finger sizes. This article demonstrates the modeling of soft pneumatic actuators and highlights the potential of the RA-Glove as a therapeutic device for the prevention of arthritic deformities of the fingers.

The efficacy of forceful ankle and toe exercises to increase venous return: A comprehensive Doppler ultrasound study

Objective Venous stasis is a risk factor for venous thromboembolism. We aimed to determine the efficacy of forceful foot exercises for actuation of the calf muscle pump to counteract stasis. Methods We examined 20 seated healthy subjects. The peak systolic velocity at the level of the popliteal vein was assessed by Doppler ultrasound. Results The mean peak systolic velocity measurements (in cm/s) were as follows: baseline = 5.6; ankle plantar flexion with toe flexion = 91.0; toe touch heel lift = 107.4; ankle dorsiflexion with toe extension = 193.6; isolated flexion of all toes = 118.8; ankle plantarflexion with 100 and 250 Newton forefoot force = 89.9 and 154.5, respectively. Conclusion All exercises achieved significant increases in peak systolic velocity compared to baseline. Ranking showed that forceful ankle dorsiflexion, plantarflexion with 250 Newtons and forceful flexion of all toes yielded the highest mean peak systolic velocity values (193.6, 154.5, and 118.8 cm/s, respectively).

Venous haemodynamics of Jet Impulse Technology within a lower limb fibreglass cast: a randomized controlled trial

Objectives

We investigated popliteal venous haemodynamics of the VenaJet Jet Impulse Technology system within a below-knee fibreglass cast.

Design

Randomized controlled trial.

Participants

Twenty-four healthy participants aged 18–54 had both feet placed within the Jet Impulse Technology system and were randomised for one or other leg to be within a below-knee fibreglass cast.

Setting

Pacific Radiology, Lower Hutt, Wellington

Main outcome measures

The primary outcome variable was peak systolic velocity (cm/s) compared between legs with and without the cast at 60 min (after 10 min Jet Impulse Technology activation), using a mixed linear model and a non-inferiority bound of 4.8 cm/s. Secondary outcome variables were the difference in peak systolic velocity between the casted limb and the non-casted limb at baseline and 40 min after casting, and the difference in mean flow velocity (cm/s), vein diameter (mm), and total volume flow (L/min) between the casted limb and the non-casted limb at baseline, 40 and 60 min.

Results

The mean (standard deviation) peak systolic velocity was 4.6(1.5), 4.8(1.1), 28.8(16.1), and 4.3(1.2), 4.8(1.4) and 29.3(19.0) cm/s at baseline, 40 and 60 min in the casted and non-casted leg, respectively. The difference (95% confidence interval) between cast and no-cast at 60 min was −0.8 (−6.5 to 4.9) cm/s, P = 0.78. The peak systolic velocity, flow velocity and total volume flow at 40 min were not statistically significantly different from baseline for both casted and non-casted limb.

Conclusion

In healthy volunteers, the popliteal venous haemodynamics of the Jet Impulse Technology system was similar between the legs with and without a below-knee fibreglass cast. In-cast Jet Impulse Technology may provide a non-pharmacological option for venous thromboembolism prophylaxis for lower-limb cast-immobility.

Cohort feasibility study of an intermittent pneumatic compression device within a below-knee cast for the prevention of venous thromboembolism

OBJECTIVES

To determine the likely enrolment rate of eligible participants into a randomised controlled trial (RCT) in which a within-cast intermittent pneumatic compression device using Jet Impulse Technology (IPC/JIT) is 1 of 3 possible interventions in a RCT for the prevention of venous thromboembolism (VTE) in the clinical setting of isolated lower limb cast immobilisation.

DESIGN

A prospective, open-label feasibility study of the IPC/JIT device placed within a lower limb cast.

SETTING

Wellington Regional Hospital Fracture Clinic.

PARTICIPANTS

Individuals aged 18-70 who presented with a lower limb injury requiring a minimum of 4 weeks below-knee cast immobilisation.

INTERVENTION

Placement of an IPC/JIT device within lower limb cast.

OUTCOME MEASURES

The main outcome measure was the proportion of eligible participants who participated in the feasibility study. Secondary outcome measures included adherence to device usage throughout the study, ease of application of the device and adverse events potentially associated with its use.

RESULTS

The proportion of potentially eligible participants for the IPC/JIT device was only 7/142 (5%), 95% CI 2 to 9.9. Devices were used for a mean (range) of 4.1 (1.9 to 10.2) hours per day and none of 7 participants had adequate adherence to the device. 3 of the 7 participants suffered an adverse event, including 1 deep vein thrombosis, 2 dorsal foot ulcer and 1 skin maceration.

CONCLUSIONS

A within-cast IPC/JIT device is unlikely to be a feasible randomisation arm for a RCT assessing possible interventions for the reduction of VTE risk in the clinical setting of lower limb injury requiring below knee cast immobilisation for a minimum of 4 weeks.

TRIAL REGISTRATION NUMBER

ANZCTR 12615000192583.

Effect of sequential pneumatic compression therapy on venous blood velocity, refilling time, pain and quality of life in women with varicose veins: a randomized control study

[Purpose] The aim of this study was to investigate the effects of sequential pneumatic compression therapy on venous blood flow, refilling time, pain level, and quality of life in women with varicose veins. [Subjects and Methods] Twenty-eight females with varicose veins were selected and randomly allocated to a control group, and experimental group. Maximum and mean venous blood velocities, the refilling time, pain by visual analog scale and quality of life by Aberdeen Varicose Veins Questionnaire were measured in all patients before and after six weeks of treatment. Both groups received lower extremity exercises; in addition, patients in the experimental group received sequential pneumatic compression therapy for 30 minutes daily, five days a week for six weeks. [Results] All measured parameters improved significantly in both groups, comparison of post treatment measurements between groups showed that the maximum and mean blood flow velocity, the pain level, and quality of life were significantly higher in the experimental group compared with the control group. On the other hand there was no significant difference between groups for refilling time. [Conclusion] Sequential pneumatic compression therapy with the applied parameters was an effective modality for increasing venous blood flow, reducing pain, and improving quality of women life with varicose veins.

Increasing Circulation in the Lower Limb Under General Anesthesia Using the A-V Impulse System

The action of foot impulse technology (FIT) in reducing the risk of deep vein thrombosis (DVT) is well established. We hypothesized that intraoperative use of FIT devices will be effective in the prophylaxis of DVT. The aim of this study was to investigate the effect of a FIT device (A-V impulse system) on the venous flow of the lower extremity using duplex ultrasound scanning while the patient was under general anesthesia. Thirteen surgical patients who had no lower limb vessel lesions were selected for the study. Duplex scanning was used to measure blood velocity in the right common femoral vein, with and without the foot pump, before and during general anesthesia. The mean resting velocity was 33.2 ±5.5 cm/sec in the pre-anesthetic state, 32.1 ±4.2 cm/sec under anesthetic, and 30.4 ±5.0 cm/sec postoperatively. The peak velocities with the pump active were 38.6 ±5.0 cm/sec before anesthetic, 54.6 ±5.9 cm/sec while anesthetized, and 52.7 ±7.8 cm/sec postoperatively. The measured increases while under anesthesia and postoperatively both reached statistical significance (p < 0.05). Our study demonstrated that use of the A-V impulse system causes a statistically significant increase in venous velocity of the lower extremity while the patient is under general anesthesia.

The Unilateral Swollen Lower Limb: Etiology, Investigation, and Management

The swollen lower limb, a common finding in routine clinical practice, is clinically challenging. The cause underlying this problem is often multifactorial, and its management may involve different specialties. It is important, though difficult, to avoid unnecessary and expensive investigations. The aim of this article is to provide an overview of the management of this problem by addressing the common causes, methods of assessment, diagnosis, and therapeutic options.

Investigation of Blood Flow During Intermittent Pneumatic Compression and Proposal of a New Compression Protocol

INTRODUCTION

Intermittent pneumatic compression (IPC) is now a widely used therapy for the prophylaxis of deep vein thrombosis and pulmonary embolism. In general, the IPC sequence is composed of sequential compression and simultaneous deflation. Typically, veins are considered to be squeezed and emptied during the compression phase and to be refilled during the deflation phase. However, because the stop or sudden increase in blood flow can be dangerous, a further investigation is needed with respect to the blood flow.

MATERIALS AND METHODS

We demonstrated a new compression protocol based on the investigation results of venous blood flow during IPC. This new compression protocol involves successive compression without the deflation phase; thus, the expelled blood volume flow during a given period can be maximized. To investigate the blood flow during IPC, sonography movie clips and in-laboratory developed blood flow analysis software was used.

RESULTS

The increases in the peak volume flow during IPC were 49% (±24%) and 25% (±29%) with the conventional protocol and the new protocol, respectively, whereas the total volume flow (TVF) was not significantly changed (-1.0% and -13.0%, respectively). With the new protocol, the peak velocity (PV) was 49% lower than that with the conventional protocol. Thus, the new protocol has an effect of maintaining TVF without resulting in a sudden large increase or decrease in PV.

CONCLUSION

The new suggested protocol might improve safety because it can maintain the stability of blood flow by reducing the risk of blood stasis and a rapid change in blood flow.

Comparison of 4-Layer Bandages and an Adaptive Compression Therapy Device on Intended Pressure Delivery

PURPOSE

To characterize and compare interface pressure profiles of an adaptive compression therapy (ACT) device and a traditional 4-layer bandage (4LB) system.

DESIGN

A prospective, randomized, open-label, 1-arm, active controlled study.

SUBJECTS

The sample comprised 12 healthy volunteers.

METHODS

Subjects wore both devices for 8 hours on 3 consecutive days. Treatments were randomized to left and right legs. One clinician performed all applications and was experienced in the clinical use of both devices. Pressures were measured in seated and standing positions at the lower, mid, and upper calf immediately post application and after 1, 4, and 8 hours.

RESULTS

Pressures achieved with the ACT were closer to targeted 40/30/20 mmHg graduated pressure values and were significantly less than the 4LB for corresponding sites/postures (P < .001). In the seated position, initial interface pressures (mean ± SD) for the ACT were 36.9 ± 4.9, 30.5 ± 4.5, and 21.0 ± 3.6 mmHg. Corresponding interface pressures for the 4LB were 52.5 ± 8.4, 57.5 ± 10.3, and 53.5 ± 12.9 mmHg. In the standing position, initial interface pressures for the ACT were 40.7 ± 4.8, 35.6 ± 4.5, and 21.1 ± 4.6 compared to 54.6 ± 12.5, 64.4 ± 10.9, and 53.7 ± 14.3 for the 4LB. At 1, 4, and 8 hours after application, the 4LB showed a significant progressive decline in interface pressure in both seated and standing positions (P < .001). Conversely, the ACT did not decrease over time and there was a slight but significant increase for lower and mid-calf sites in the seated position (P < .001).

CONCLUSIONS

The ACT device provided more consistent interface pressures than the 4LB and the pressures achieved were consistent with contemporary venous ulcer therapy standards.

Neuromuscular electrical stimulation for thromboprophylaxis: A systematic review

OBJECTIVE

To evaluate the effect of neuromuscular electrical stimulation on lower limb venous blood flow and its role in thromboprophylaxis.

METHOD

Systematic review of randomised and non-randomised studies evaluating neuromuscular electrical stimulation, and reporting one or more of the following outcomes: incidence of venous thromboembolism, venous blood flow and discomfort profile.

RESULTS

Twenty-one articles were identified. Review of these articles showed that neuromuscular electrical stimulation increases venous blood flow and is generally associated with an acceptable tolerability, potentially leading to good patient compliance. Ten comparative studies reported DVT incidence, ranging from 2% to 50% with neuromuscular electrical stimulation and 6% to 47.1% in controls. There were significant differences, among included studies, in terms of patient population, neuromuscular electrical stimulation delivery, diagnosis of venous thromboembolism and blood flow measurements.

CONCLUSION

Neuromuscular electrical stimulation increases venous blood flow and is well tolerated, but current evidence does not support a role for neuromuscular electrical stimulation in thromboprophylaxis. Randomised controlled trials are required to investigate the clinical utility of neuromuscular electrical stimulation in this setting.

Different types of intermittent pneumatic compression devices for preventing venous thromboembolism in patients after total hip replacement

BACKGROUND

Total hip replacement (THR) is an effective treatment for reducing pain and improving function and quality of life in patients with hip disorders. While this operation is very successful, deep vein thrombosis (DVT) and pulmonary embolism (PE) are significant complications after THR. Different types of intermittent pneumatic compression (IPC) devices have been used for thrombosis prophylaxis in patients following THR. Available devices differ in compression garments, location of air bladders, patterns of pump pressure cycles, compression profiles, cycle length, duration of inflation time and deflation time, or cycling mode such as automatic or constant cycling devices. Despite the widely accepted use of IPC for the treatment of arterial and venous diseases, the relative effectiveness of different types of IPC systems as prophylaxis against thrombosis after THR is still unclear.

OBJECTIVES

To assess the comparative effectiveness and safety of different IPC devices with respect to the prevention of venous thromboembolism in patients after THR.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Coordinator searched the Specialised Register (November 2014), CENTRAL (2014, Issue 10). Clinical trial databases were searched for details of ongoing and unpublished studies. Reference lists of relevant articles were also screened. There were no limits imposed on language or publication status.

SELECTION CRITERIA

Randomized and quasi-randomized controlled studies were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trials for eligibility and methodological quality, and extracted data. Disagreement was resolved by discussion or, if necessary, referred to a third review author.

MAIN RESULTS

Only one quasi-randomized controlled study with 121 study participants comparing two types of IPC devices met the inclusion criteria. The authors found no cases of symptomatic DVT or PE in either the calf-thigh compression group or the plantar compression group during the first three weeks after the THR. The calf-thigh pneumatic compression was more effective than plantar compression for reducing thigh swelling during the early postoperative stage. The strength of the evidence in this review is weak as only one trial was included and it was classified as having a high risk of bias.

AUTHORS' CONCLUSIONS

There is a lack of evidence from randomized controlled trials to make an informed choice of IPC device for preventing venous thromboembolism (VTE) following total hip replacement. More research is urgently required, ideally a multicenter, properly designed RCT including a sufficient number of participants. Clinically relevant outcomes such as mortality, imaging-diagnosed asymptomatic VTE and major complications must be considered.

Comparative lower limb hemodynamics using neuromuscular electrical stimulation (NMES) versus intermittent pneumatic compression (IPC)

Deep Vein Thrombosis (DVT) is a life threatening condition and a serious concern among hospitalised patients, with death occurring in approximately 6% of cases. Intermittent pneumatic compression (IPC) is commonly used for DVT prevention, however suffers from low compliance and issues of usability and portability. Neuromuscular electrical stimulation (NMES) has been shown to improve lower limb hemodynamics but direct comparison with IPC in terms of hemodynamics is rare but very important to determine the potential effectiveness of NMES in DVT prevention.Lower limb IPC was compared to calf NMES, in 30 healthy volunteers (18-23 years). Each intervention was carried out on each leg, on the popliteal vein measured using Doppler ultrasound. All interventions produced significantly greater haemodynamic responses compared to baseline. Calf-IPC and NMES produced significant increases in venous blood velocity (cm/s) and volume of blood ejected per cycle (1 cycle of NMES expels 23.22 ml compared to the baseline ejected volume of 2.52 ml, measured over 1 s (p < 0.001 versues baseline).Improving lower limb hemodynamics is vital in preventing DVT. NMES resulted in larger ejected volumes compared to IPC (x3 greater than foot-IPC and x1.7 greater than calf-IPC) more effectively emptying the veins and soleal sinuses. This is an important finding as DVT occurs predominantly in the soleal sinuses. NMES is silent and portable and thus does not suffer many of the issues associated with IPC. This work supports the potential widespread application of NMES in hospital and home settings where the risk of DVT formation is high.

Acute oxygenation changes on ischemic foot of a novel intermittent pneumatic compression device and of an existing sequential device in severe peripheral arterial disease

Background

Intermittent pneumatic compression (IPC) improves haemodynamics in peripheral arterial disease (PAD), but its effects on foot perfusion were scarcely studied. In severe PAD patients we measured the foot oxygenation changes evoked by a novel intermittent IPC device (GP), haemodynamics and compliance to the treatment. Reference values were obtained by a sequential foot-calf device (SFC).

Methods

Twenty ischemic limbs (Ankle-Brachial Index = 0.5 ± 0.2) of 12 PAD patients (7 male, age: 74.5 ± 10.8 y) with an interval of 48 ± 2 hours received a 35 minute treatment in supine position with two IPC devices: i) a Gradient Pump (GP), which slowly inflates a single thigh special sleeve and ii) an SFC (ArtAssist^®, ACI Medical, San Marcos, CA, USA), which rapidly inflates two foot-calf sleeves. Main outcome measure: changes of oxygenated haemoglobin at foot (HbO_2foot) by continuous near-infrared spectroscopy recording and quantified as area-under-curve (AUC) for periods of 5 minutes. Other measures: haemodynamics by echo-colour Doppler (time average velocity (TAV) and blood flow (BF) in the popliteal artery and in the femoral vein), patient compliance by a properly developed form.

Results

All patients completed the treatment with GP, 9 with SFC. HbO_2foot during the working phase, considered as average value of the 5 minutes periods, increased with GP (AUC 458 ± 600 to 1216 ± 280) and decreased with SFC (AUC 231 ± 946 to −1088 ± 346), significantly for most periods (P < 0.05). The GP treatment was associated to significant haemodynamic changes from baseline to end of the treatment (TAV = 10.2 ± 3.3 to 13.5 ± 5.5 cm/sec, P = 0.004; BF = 452.0 ± 187.2 to 607.9 ± 237.8 ml/sec, P = 0.0001), not observed with SFC (TAV = 11.2 ± 3.4 to 11.8 ± 4.3 cm/sec; BF = 513.8 ± 203.7 to 505.9 ± 166.5 ml/min, P = n.s.). GP obtained a higher score of patient compliance (P < 0.0001).

Conclusions

A novel IPC thigh device, unlike a traditional SFC device, increased foot oxygenation in severe PAD, together with favourable haemodynamic response and high compliance to the treatment under the present experimental conditions.

Physiology in medicine: peripheral arterial disease

Peripheral arterial disease (PAD) is an atherosclerotic condition that can provoke symptoms of leg pain ("intermittent claudication") during exercise. Because PAD is often observed with comorbid conditions such hypertension, dyslipidemia, diabetes, cigarette smoking, and/or physical inactivity, the pathophysiology of PAD is certainly complex and involves multiple organ systems. Patients with PAD are at high risk for myocardial infarction, stroke, and all-cause mortality. For this reason, a better physiological understanding of the pathogenesis and treatment options for PAD patients is necessary and forms the basis of this Physiology in Medicine review.

Superior hemodynamic performance of a thigh-length versus knee-length intermittent pneumatic compression device

OBJECTIVE

There is a lack of consensus regarding which length of intermittent pneumatic compression (IPC) device provides optimal thromboprophylaxis. This trial was conducted to compare hemodynamic performance of a thigh-length and knee-length IPC device. The hypothesis is that thigh-length IPC will be more efficient in preventing stasis.

METHODS

This single-center trial tested the thigh-length sleeve (TLS) and knee-length sleeve (KLS) in 47 healthy volunteers. Peak systolic velocity and total volume flow were measured at rest and during the 11-second compression cycle. Measurements were obtained at the popliteal vein for the KLS and at the common femoral vein for the TLS.

RESULTS

The study was completed by 47 volunteers (32 women, 15 men), who were a mean age of 39.7 years (range, 18-68 years). There was a statistically significant difference in augmented total volume flow and peak systolic velocity between the KLS and TLS favoring the TLS: median total volume flow was 357.54 mL/min for the KLS vs 668.21 mL/min for the TLS (P < .0001), and median peak systolic velocity was 47.70 cm/s for the KLS vs 58.47 cm/s for the TLS (P = .0019).

CONCLUSIONS

This trial suggests that the improved hemodynamic effects of a thigh-length IPC system may provide superior thromboprophylaxis to a knee-length IPC.

Different types of intermittent pneumatic compression devices for preventing venous thromboembolism in patients after total hip replacement

BACKGROUND

Total hip replacement (THR) is an effective treatment for reducing pain and improving function and quality of life in patients with hip disorders. While this operation is very successful, deep vein thrombosis (DVT) and pulmonary embolism (PE) are significant complications after THR. Different types of intermittent pneumatic compression (IPC) devices have been used for thrombosis prophylaxis in patients following THR. Available devices differ in compression garments, location of air bladders, patterns of pump pressure cycles, compression profiles, cycle length, duration of inflation time and deflation time, or cycling mode such as automatic or constant cycling devices. Despite the widely accepted use of IPC for the treatment of arterial and venous diseases, the relative effectiveness of different types of IPC systems as prophylaxis against thrombosis after THR is still unclear.

OBJECTIVES

To assess the comparative effectiveness and safety of different IPC devices with respect to the prevention of venous thromboembolism in patients after THR.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Coordinator searched the Specialised Register (May 2012), CENTRAL (2012, Issue 4), MEDLINE (April Week 3 2012) and EMBASE (Week 17 2012). Clinical trial databases were searched for details of ongoing and unpublished studies. Reference lists of obtained articles were also screened. There were no limits imposed on language or publication status.

SELECTION CRITERIA

Randomized and quasi-randomized controlled studies were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trials for eligibility and methodological quality, and extracted data. Disagreement was resolved by discussion or, if necessary, referred to a third review author.

MAIN RESULTS

Only one quasi-randomized controlled study with 121 study participants comparing two types of IPC devices met the inclusion criteria. The authors found no cases of symptomatic DVT or PE in either the calf-thigh compression group or the plantar compression group during the first three weeks after the THR. The calf-thigh pneumatic compression was more effective than plantar compression for reducing thigh swelling during the early postoperative stage. The strength of the evidence in this review is weak as only one trial was included and it was classified as having a high risk of bias.

AUTHORS' CONCLUSIONS

There is a lack of evidence from randomized controlled trials to make an informed choice of IPC device for preventing venous thromboembolism (VTE) following total hip replacement. More research is urgently required, ideally a multicenter, properly designed RCT including a sufficient number of participants. Clinically relevant outcomes such as mortality, imaging-diagnosed asymptomatic VTE and major complications must be considered.

Comparing hemodynamic effects with three different measurement devices, of two methods of external leg compression versus passive leg raising in patients after cardiac surgery

External leg compression (ELC) may increase cardiac output (CO) in fluid-responsive patients like passive leg raising (PLR). We compared the hemodynamic effects of two methods of ELC and PLR measured by thermodilution (COtd), pressure curve analysis Modelflow™ (COmf) and ultra-sound HemoSonic™ (COhs), to evaluate the method with the greatest hemodynamic effect and the most accurate less invasive method to measure that effect. We compared hemodynamic effects of two different ELC methods (circular, A (n = 16), vs. wide, B (n = 13), bandages inflated to 30 cm H2O for 15 min) with PLR prior to each ELC method, in 29 post-operative cardiac surgical patients. Hemodynamic responses were measured with COtd, COmf and COhs. PLR A increased COtd from 6.1 ± 1.7 to 6.3 ± 1.8 L·min(-1) (P = 0.016), and increased COhs from 4.9 ± 1.5 to 5.3 ± 1.6 L·min(-1) (P = 0.001), but did not increase COmf. ELC A increased COtd from 6.4 ± 1.8 to 6.7 ± 1.9 L·min(-1) (P = 0.001) and COmf from 6.9 ± 1.7 to 7.1 ± 1.8 L·min(-1) (P = 0.021), but did not increase COhs. ELC A increased COtd and COmf as in PLR A. PLR B increased COtd from 5.4 ± 1.3 to 5.8 ± 1.4 L·min(-1) (P < 0.001), and COhs from 5.0 ± 1.0 to 5.4 ± 1.0 L·min(-1) (P = 0.013), but not COmf. ELC B increased COtd from 5.2 ± 1.2 to 5.4 ± 1.1 L·min(-1) (P = 0.003), but less than during PLR B (P = 0.012), while COmf and COhs did not change. Bland-Altman and polar plots showed lower limits of agreement with changes in COtd for COmf than for COhs. The circular leg compression increases CO more than bandage compression, and is able to increase CO as in PLR. The less invasive Modelflow™ can detect these changes reasonably well.

Acute impact of intermittent pneumatic leg compression frequency on limb hemodynamics, vascular function, and skeletal muscle gene expression in humans

The mechanisms by which intermittent pneumatic leg compression (IPC) treatment effectively treats symptoms associated with peripheral artery disease remain speculative. With the aim of gaining mechanistic insight into IPC treatment, the purpose of this study was to investigate the effect of IPC frequency on limb hemodynamics, vascular function, and skeletal muscle gene expression. In this two study investigation, healthy male subjects underwent an hour of either high-frequency (HF; 2-s inflation/3-s deflation) or low-frequency (LF; 4-s inflation/16-s deflation) IPC treatment of the foot and calf. In study 1 (n = 11; 23.5 ± 4.7 yr), subjects underwent both HF and LF treatment on separate days. Doppler/ultrasonography was used to measure popliteal artery diameter and blood velocity at baseline and during IPC treatment. Flow-mediated dilation (FMD) and peak reactive hyperemia blood flow (RHBF) were determined before and after IPC treatment. In study 2 (n = 19; 22.0 ± 4.6 yr), skeletal muscle biopsies were taken from the lateral gastrocnemius of the treated and control limb at baseline and at 30- and 150-min posttreatment. Quantitative PCR was used to assess mRNA concentrations of genes associated with inflammation and vascular remodeling. No treatment effect on vascular function was observed. Cuff deflation resulted in increased blood flow (BF) and shear rate (SR) in both treatments at the onset of treatment compared with baseline (P < 0.01). BF and SR significantly diminished by 45 min of HF treatment only (P < 0.01). Both treatments reduced BF and SR and elevated oscillatory shear index compared with baseline (P < 0.01) during cuff inflation. IPC decreased the mRNA expression of cysteine-rich protein 61 from baseline and controls (P <0 .01) and connective tissue growth factor from baseline (P < 0.05) in a frequency-dependent manner. In conclusion, a single session of IPC acutely impacts limb hemodynamics and skeletal muscle gene expression in a frequency-dependent manner but does not impact vascular function.

Magnetic resonance venous velocity mapping during intermittent pneumatic compression of the calf and foot

Objective

Assessment and optimization of intermittent pneumatic compression (IPC) devices for prophylaxis of deep vein thrombosis has previously used duplex ultrasound. The aim was to investigate novel magnetic resonance (MR) venous velocity mapping (VM) for IPC research and development.

Methods

Twelve normal subjects were scanned in the supine position using realtime MR VM with sequential foot and calf IPC (120 mmHg) at 1.5 T. Measurements were taken in the popliteal vein at baseline using both cuffs and each cuff individually recording 60 seconds continuously. Temporal resolution was 310 ms per independent image, at 1 ×1 mm spatial resolution.

Results

Peak velocity ( Vp) measurements: baseline, Vp = 2.1 cm/second (range = 1.1–3.5); using both compression cuffs, Vp = 41.5 cm/second (18.0–58.1); calf cuff alone, Vp = 40.6 cm/second (18.1–62.2); foot cuff alone, Vp = 7.9 cm/second (4.2–15.3). Flow volume measurements per compression cycle ( F): baseline, F = 2.3 cm3 (0.5–11.4); both compression cuffs, F = 7.1 cm3 (2.5–24.6); calf cuff only, F = 7.1 cm3 (2.4–24.5); foot cuff only, F = 2.6 cm3 (0.9–10.7). The foot cuff contribution was insignificant when combined with the calf cuff ( P < 0.01). The MR venous VM results were similar to those reported elsewhere using ultrasound.

Conclusion

This novel technique for MR venous VM can measure the realtime variations in venous blood flow during IPC.

Micro-mobile foot compression device compared with pneumatic compression device

BACKGROUND

A combination mechanical-pharmacologic regimen is an accepted prophylactic treatment against symptomatic venous thromboembolism for patients undergoing total hip and knee arthroplasties. Foot pumps have been recognized as effective mechanical devices. Research suggests pharmacologic prophylaxis for venous thromboembolism is associated with complications and foot pumps offer an adjunct or alternative approach. Presumably the effectiveness of foot pumps relate to enhancement of venous flow.

QUESTIONS/PURPOSES

We compared an established foot pump system with a new mobile foot pump for their ability to influence mean peak venous velocity in the common femoral, popliteal, and posterior tibial veins.

METHODS

We evaluated 60 healthy subjects with the established and the novel foot-pump systems. Ultrasonography was used to measure baseline and peak venous velocity with mechanical compression. We constructed 95% confidence intervals (CI) on the mean differences between the two devices to establish equivalence limits. We compared ratios of peak velocity to resting velocity. Subjects subjectively rated the two foot pumps with respect to size, fit, and comfort.

RESULTS

The 95% CI test for equivalence of the mean differences between the two devices was inconclusive. The novel device augmented the venous velocity 11 times greater than the resting velocity in the posterior tibial vein and three times greater than the resting velocity in the popliteal vein. The established foot pump augmented the venous velocity 15 times greater than the resting velocity in the posterior tibial vein and four times greater than the resting velocity in the popliteal vein. The novel device rated better for size, fit, and comfort when compared with the established device.

CONCLUSIONS

The established foot pump tended to be associated with greater peak velocities; the novel device produced more consistent mean peak venous velocities and may be more acceptable to patients and caregivers.

Venous emptying from the foot: influences of weight bearing, toe curls, electrical stimulation, passive compression, and posture

This study investigated the hemodynamic properties of the plantar venous plexus (PVP), a peripheral venous pump in the human foot, with Doppler ultrasound. We investigated how different ways of introducing mechanical changes vary in effectiveness of displacing blood volume from the PVP. The contribution of the PVP was analyzed during both natural and device-elicited compressions. Natural compressions consisted of weight bearing on the foot and toe curl exercises. Device-elicited compressions consisted of intermittent pneumatic compression (IPC) of the foot and electrically elicited foot muscle contractions. Ten healthy participants had their posterior tibial, peroneal, anterior tibial, and popliteal vein blood flow monitored while performing these natural and device-elicited compressions of the PVP supine and in an upright position. Results indicated that 1) natural compression of the PVP, weight bearing and toe curls, expelled a significantly larger volume of blood than device-elicited PVP compression, IPC and electrical stimulation; 2) there was no difference between the venous volume elicited by weight bearing and by toe curls; 3) expelled venous volume recorded at the popliteal vein under all test conditions was significantly greater than that recorded from the posterior tibial and peroneal veins; 4) there was no significant difference between the volume in the posterior tibial and peroneal veins; 5) ejected venous volume recorded in the upright position was significantly higher than that recorded in the supine position. Our study shows that weight bearing and toe curls make similar contributions to venous emptying of the foot.

A pilot evaluation of a neuromuscular electrical stimulation (NMES) based methodology for the prevention of venous stasis during bed rest

Bed rest poses an increased risk factor for a potentially fatal venous thromboembolism (VTE). Lack of activation of the calf muscle pump during this resting period gives rise to venous stasis which may lead to deep vein thrombosis (DVT) development. Our aim was to investigate the effects that 4h of bed rest have on the lower limb hemodynamics of healthy subjects and to what extent electrically elicited contractions of the calf muscles can alleviate these effects. Outcome variables included popliteal vein blood flow and heart rate. Primary results indicated that the resting group experienced a significant decline in popliteal venous blood flow of approximately 47% with approximately 13% decrease in heart rate. The stimulated groups maintained a significantly higher venous blood flow and heart rate. Volume flow in the contralateral limb remained constant throughout the study and was comparable to that of the stimulated limb's recovery flow. The results suggest that even short periods of bed rest can significantly reduce lower limb blood flow which could have implications for DVT development. Electrically elicited calf muscle contractions significantly improve lower limb blood flow and can alleviate some debilitating effects of bed rest.

The impact of intermittent pneumatic compression devices on deep venous flow velocity in patients with congestive heart failure

BACKGROUND

Intermittent pneumatic compression (IPC) has been used to prevent deep venous thrombosis (DVT), but the effects of IPC on the hemodynamics of popliteal and soleal veins, especially in patients with congestive heart failure (CHF) have not been evaluated. The aim of this study was to evaluate the effects of IPC on the flow velocity of deep veins in the lower extremities and to compare the efficacy of two different types of IPC in deep venous flow enhancement in patients with CHF.

METHODS

Flow velocities of popliteal and soleal veins were recorded in 19 patients with CHF and in 19 control subjects using a high-resolution linear probe. Peak and mean flow velocities were measured (1) at rest, (2) with sequential foot and calf IPC (SFC-IPC) which consists of an electrically driven air compressor and four air chambers, and (3) with impulse foot IPC (IF-IPC) which consists of a pneumatic impulse generator operated at an applied pressure of 130 mmHg.

RESULTS

In the resting condition, popliteal venous flow velocity in the CHF group was attenuated (12.8+/-4.7 cm/s vs. 21.1+/-13.5 cm/s; p<0.05). Both SFC-IPC and IF-IPC increased venous velocity, but the increase with IF-IPC in CHF patients was lower than that in control subjects. In the soleal veins, after applying SFC-IPC, the peak and mean velocity in CHF increased to the same extent as in the control group. IF-IPC increased soleal venous velocity in control subjects, but there was no increase in CHF patients.

CONCLUSION

Two-dimensional Doppler scanning revealed a significant increase in the mean and peak velocities in the soleal and popliteal veins with SFC-IPC but not with IF-IPC in patients with CHF. These results indicate that SFC-IPC could have favorable effects in preventing DVT in patients with CHF.

Eficácia da compressão pneumática intermitente (CPI) nos membros inferiores sobre o fluxo sanguíneo das veias femorais comuns

CONTEXTO: A profilaxia do tromboembolismo venoso pode ser feita por métodos farmacológicos ou de forma mecânica, com o uso de meias antitrombo e compressão pneumática (CPI). A CPI é um método mecânico de profilaxia que merece melhor atenção da comunidade médica. OBJETIVO: Avaliar o efeito do uso de compressão pneumática intermitente (CPI) nos pés, pernas e coxas de adultos saudáveis sobre o fluxo sanguíneo nas veias femorais comuns. MÉTODOS: A amostra foi constituída de 10 voluntários (sete mulheres e três homens) adultos (20-40 anos), sem antecedente de tromboembolismo venoso. Após repouso (10 min) em decúbito dorsal, o fluxo sanguíneo era medido (três vezes) por ultra-sonografia vascular na veia femoral, a 1 cm acima da junção safeno-femoral, em ambos os membros, sem controle e com CPI no pé, perna e na coxa. A compressão (130 mmHg no pé e 45 mmHg na perna e na coxa) foi aplicada em ciclos de 11 segundos de compressão e 20-60 segundos de esvaziamento. As aferições de fluxo foram realizadas no pico de fluxo do ciclo de compressão. Os valores foram comparados por análise de variância (teste de Tukey), com p < 0,05 indicando diferença estatisticamente significante. RESULTADO: A utilização de CPI nos membros inferiores, esquerdo e direito, promoveu elevações percentuais relativas no fluxo venoso femoral de 37,6 e 70,8% (pés), 143,9 e 164,7% (pernas) e 132,6 e 128,9% (coxas), respectivamente. As variações foram estatisticamente significantes para as aplicações nas pernas e coxas. CONCLUSÃO: A CPI melhora o fluxo sanguíneo quando aplicada na perna ou na coxa.

Intermittent pneumatic compression in immobile patients

The purpose of this study is to stress the value of using intermittent pneumatic compression (IPC) in immobile patients. The use of IPC helps prevent limb oedema and the associated skin changes frequently seen on the legs of the immobile patient. Oedema formation is caused by an increase of fluid extravasation, while skin changes including leg ulcers are mainly because of a deficiency of the venous and lymphatic pumps. Conventional compression stockings and bandages impede leg swelling but are less efficient in supporting the deficient veno-lymphatic pump when patients are unable to move. In this situation, actively compressing the limb using IPC is a very meaningful and effective treatment option. Because of a lack of literature on the specific indication of IPC in immobile patients, experimental studies and randomised controlled trials in similar situations are reviewed. IPC is a very effective although underused treatment modality, especially in immobile, wheelchair-bound patients. By inflation and deflation of the air-filled garments, IPC produces cycles of pressure waves on the leg, thus mimicking the working and resting pressures applied by compression bandages. IPC not only reduces leg swelling but also augments the veno-lymphatic pump, which is essential for the restoration of the damaged microcirculation of the skin.

Intermittent pneumatic soft tissue compression: Changes in periosteal and medullary canal blood flow

We previously demonstrated that the use of intermittent pneumatic soft tissue compression (IPC) treatment enhanced fracture healing in an animal model, but the exact mechanism remained unknown. The purpose of this study was to determine the local and remote effects of IPC treatment on blood flow within the medullary canal and outside the periosteum of mid-tibial diaphysis. Blood flow was measured with a Laser Doppler blood flow meter in the lower limbs of 21 rabbits. Laser probes were inserted at three different sites of the mid-diaphysis on the right tibia: in the medullary canal (n = 21), outside the periosteum on the lateral side (n = 11), and outside the periosteum on the medial side (n = 10). IPC was applied for 30 min through cuffs that were placed around the feet and the lower part of the calf. While applying IPC to the left leg, no changes in blood flow occurred on the right leg (remote changes). However, while applying IPC to the right leg, significant localized changes were found on the right leg, including 47 and 89% increases in total amount of blood flow outside the lateral and medial periosteum, respectively. Although an altered blood flow pattern was observed in the medullary canal, no significant change in total amount of blood flow was observed at this level. In summary, the present study demonstrated that the use of IPC in an intact bone model results in a significant local increase in total blood flow, with minimal measurable effects on the contralateral limb.

The venous pump of the first metatarsophalangeal joint: clinical implications

BACKGROUND

Although the anatomy and physiology of the venous circulation of the ankle and midfoot are well documented, the physiologic importance of forefoot mobility has not been reported in the literature. The question of this study was whether the first metatarsophalangeal (MTP) joint may operate, like the ankle, as a "pump" to encourage venous return.

METHODS

Forty-nine cadaver foot specimens were examined using dissection, plastination, vessel infiltration, and maceration, and radiographic (including venography, MRI, and magnetic resonance angiography) techniques. The anatomy and physiology were described and compared to the ankle joint. Forty patients had biphasic Doppler flow studies.

RESULTS

The major finding was the medial drainage of the plantar venous sinus, which is fibrotically bound to the joint capsule. Functional venous valves were evident distally and within fibrous vascular lumens. Mobilization of the first MTP joint led to compression and emptying of the veins. Passive mobilization of the first MTP joint led to an average flow increase of 55% +/- 7 (p < 0.0001), while active movement led to an average increase of 78% +/- 7 (p < 0.0001).

CONCLUSIONS

Our described connection between the joint capsule and veins indicates a "toe-ankle pump" with a significant increase of venous blood flow during motion of the MTP joint. Possible clinical applications for an external MTP pump include anti-edema or thromboprophylactic therapy, especially in patients with foot or ankle injuries. A new toe-pump has been designed based on these results.

Rapid-inflation intermittent pneumatic compression for prevention of deep venous thrombosis

BACKGROUND

Current treatment regimens that are designed to prevent deep venous thrombosis in patients undergoing orthopaedic procedures rely predominantly on drug prophylaxis alone. The purpose of this randomized clinical study was to evaluate the effectiveness of a mechanical adjunct to chemoprophylaxis that involves intermittent compression of the legs.

METHODS

During a twenty-two month period, 1803 patients undergoing a variety of orthopaedic procedures were prospectively randomized to receive either chemoprophylaxis alone or a combination of chemoprophylaxis and mechanical prophylaxis. Nine hundred and two patients were managed with low-molecular-weight heparin alone, and 901 were managed with low-molecular-weight heparin and intermittent pneumatic compression of the calves for varying time periods. Twenty-four percent of the patients underwent total hip or knee joint replacement. Screening for deep venous thrombosis was performed on the day of discharge with duplex-color-coded ultrasound.

RESULTS

In the chemoprophylaxis-only group, fifteen patients (1.7%) were diagnosed with a deep venous thrombosis; three thromboses were symptomatic. In the chemoprophylaxis plus intermittent pneumatic compression group, four patients (0.4%) were diagnosed with deep venous thrombosis; one thrombosis was symptomatic. The difference between the groups with regard to the prevalence of deep venous thrombosis was significant (p = 0.007). In the chemoprophylaxis plus intermittent pneumatic compression group, no deep venous thromboses were found in patients who received more than six hours of intermittent pneumatic compression daily.

CONCLUSIONS

Venous thrombosis prophylaxis with low-molecular-weight heparin augmented with a device that delivers rapid-inflation intermittent pneumatic compression to the calves was found to be significantly more effective for preventing deep venous thrombosis when compared with a treatment regimen that involved low-molecular-weight heparin alone.