High-pressure, rapid-inflation pneumatic compression improves venous hemodynamics in healthy volunteers and patients who are post-thrombotic

The effect of low molecular weight heparin combined with air pressure in the prevention of lower extremity venous thrombosis after cesarean section: A single-center retrospective study

In this study, we investigated the effect of low-molecular-weight heparin combined with pneumatic pressure in preventing lower extremity deep vein thrombosis after cesarean section, as well as on the visual analog scale (VAS) score. 120 women who underwent cesarean sections at full term in our hospital from January 2019 to January 2022 were included and divided into a control group (55 cases) and an observation group (65 cases) based on the different treatment methods: the control group was treated with low-molecular-weight heparin and the observation group was treated with pneumatic compression therapy based on the control group. The 2 groups were analyzed for thrombosis, clinical efficacy of the treatment methods, and VAS scores. The incidence of deep vein thrombosis in the observation group were significantly lower than in the control group (4.62% vs 21.82%, P < .05). There were no statistically significant differences in activated partial thromboplastin time, prothrombin time, and thrombin time between the 2 groups (P > .05) before treatment; however, after treatment, activated partial thromboplastin time, prothrombin time, and thrombin time in the observation group were significantly higher than those in the control group (P < .05). The clinical efficacy was significantly higher in the observation group compared with the control group (95.38% vs 78.18%, respectively). The VAS scores in the observation group were significantly lower than those in the control group (P < .05). Hence, low-molecular-weight heparin combined with pneumatic pressure therapy significantly reduces the incidence of lower limb deep vein thrombosis after cesarean section. It also improves the coagulation index and reduces post-operative pain. Therefore, it should be considered for use in clinical practice.

Use of a Mobile Intermittent Pneumatic Compression Device (Vekroosan) in Mobile Patients With Chronic Venous Disease

Background

Compression therapy is an essential part of chronic venous disorder (CVD) treatment in reducing associated complications. This observational study aimed to note the use, effects and tolerance of a mobile intermittent pneumatic calf compression (IPC) device, Vekroosan^® (DVT Solution P/L).

Methods

In 56 patients, Doppler ultrasonography was used to measure venous blood peak flow velocity (PFV) at external iliac, common femoral, distal superficial femoral and popliteal vein levels both before and after application of Vekroosan calf compressor for comparison.

Results

Vekroosan was able to show significant clinical benefit in 45 patients (80%). There was a significant increase in femoral PFV pressure in post-compression measurement when compared to the pre-compression measurement (43.1 vs. 32.4 cm/s, P < 0.001), even when patients mobilize. On average, the PFV pressure increased by 10.7 cm/s when compared to baseline. A significant decrease was seen in calf swelling after calf compression (31.3 vs. 21.9 cm, P < 0.01), also with mobilization. Eighty-seven percent of patients tolerated the device well.

Conclusions

Our study shows that use of mobile IPC devices, such as Vekroosan, is safe and effective in the treatment of CVD, can be used while mobilizing and can achieve results comparable to non-mobile devices.

Intermittent compression of the calf muscle as a countermeasure to protect blood pressure and brain blood flow in upright posture in older adults

PURPOSE

Orthostatic hypotension, leading to cerebral hypoperfusion, can result in postural instability and falls in older adults. We determined the efficacy of a novel, intermittent pneumatic compression system, applying pressure around the lower legs, as a countermeasure against orthostatic stress in older adults.

METHODS

Data were collected from 13 adults (4 male) over 65 years of age. Non-invasive ultrasound measured middle cerebral artery blood velocity (MCAv) and finger photoplethysmography measured mean arterial blood pressure (MAP). Intermittent lower leg compression was applied in a peristaltic manner in the local diastolic phase of each cardiac cycle to optimize venous return during 1-min of seated rest and during a sit-to-stand transition to 1-min of quiet standing with compression initiated 15 s before transition.

RESULTS

During seated rest, compression resulted in a 4.5 ± 6.5 mmHg increase in MAP, and 2.3 ± 2.1 cm/s increase in MCAv (p < 0.05). MAP and MCAv increased during the 15 s of applied compression before the posture transition (2.3 ± 7.2 mmHg and 2.1 ± 4.0 cm/s, respectively, p < 0.05) with main effects for both variables confirming continued benefit during the transition and quiet stand periods.

CONCLUSIONS

Application of carefully timed, intermittent compression to the lower legs of older adults increased MAP and MCAv during seated rest and maintained an elevated MAP and MCAv during a transition to standing posture. Future research could assess the benefits of this technology for persons at risk for orthostatic hypotension on standing and while walking in an effort to reduce injurious, unexplained falls in older adults.

Possible Assessment of Calf Venous Pump Efficiency by Computational Fluid Dynamics Approach

Three-dimensional simulations of peripheral, deep venous flow during muscular exercise in limbs of healthy subjects and in those with venous dysfunction were carried out by a computational fluid-dynamics (CFD) approach using the STAR CCM + platform. The aim was to assess the effects of valvular incompetence on the venous calf pump efficiency. The model idealizes the lower limb circulation by a single artery, a capillary bed represented by a porous region and a single vein. The focus is on a segment of the circuit which mimics a typical deep vein at the level of the calf muscle, such as the right posterior tibial vein. Valves are idealized as ball valves, and periodic muscle contractions are given by imposing time-dependent boundary conditions to the calf segment wall. Flow measurements were performed in two cross-sections downstream and upstream of the calf pump. Model results demonstrate a reduced venous return for incompetent valves during calf exercise. Two different degrees of valvular incompetence are considered, by restricting the motion of one or both valves. Model results showed that only the proximal valve is critical, with a 30% reduction of venous return during calf exercise in case of valvular incompetence: the net flow volume ejected by the calf in central direction was 0.14 mL per working cycle, against 0.2 mL for simulated healthy limbs. This finding appeared to be consistent with a 25% reduction of the calf ejection fraction, experimentally observed in chronic venous disease limbs compared with healthy limbs.

Fluid-Structure Coupling Model and Experimental Validation of Interaction Between Pneumatic Soft Actuator and Lower Limb

Pneumatic soft actuators (PSAs) are components that produce predesigned motion or force in different end-use devices. PSAs are lightweight, flexible, and compatible in human-machine interaction. The use of PSAs in compression therapy has proven promising in proactive pressure delivery with a wide range of dosages for treatment of chronic venous insufficiency and lymphedema. However, effective design and control of PSAs for dynamic pressure delivery have not been fully elaborated. The purpose of this study is to explore interactive working mechanisms between a PSA and lower limbs through establishing fluid-structure coupling models, an intermittent pneumatic compression (IPC) testing system, and conducting experimental validation. The developed IPC testing system consisted of a PSA unit (multichambered bladders laminated with an external textile shell), a pneumatic controller, and various real-time pressure monitoring sensors and accessory elements. The established coupling model characterized the dynamic response process with varying design parameters of the PSA unit, and demonstrated that the design of initial thickness, stiffness, and air mass flow of the PSA, as well as stiffness of limb tissues of the users, influenced PSA-lower limb interactions and resultant pressure dosages. The simulated results presented a favorable agreement with the experimental data collected by the IPC testing system. This study enhanced understanding of PSA-lower limb interactive working mechanisms and provided an evidence-based technical guidance for functional design of PSA. These results contribute to improving the efficacy of dynamic compression therapy for promotion of venous hemodynamics and user compliance in practice.

Dynamic Interface Pressure Monitoring System for the Morphological Pressure Mapping of Intermittent Pneumatic Compression Therapy

Intermittent pneumatic compression (IPC) is a proactive compression therapeutic technique in the prophylaxis of deep vein thrombosis, reduction of limb edema, and treatment of chronic venous ulcers. To appropriately detect and analyze biomechanical pressure profiles delivered by IPC in treatment, a dynamic interface pressure monitoring system was developed to visualize and quantify morphological pressure mapping in the spatial and temporal domains in real time. The system comprises matrix soft sensors, a smart IPC device, a monitoring and analysis software, and a display unit. The developed soft sensor fabricated by an advanced screen printing technology was used to detect intermitted pressure by an IPC device. The pneumatic pressure signals inside the bladders of the IPC were also transiently collected by a data acquisition system and then transmitted to the computer through Bluetooth. The experimental results reveal that the developed pressure monitoring system can perform the real-time detection of dynamic pressures by IPC and display the morphological pressure mapping multi-dimensionally. This new system provides a novel modality to assist in the effective evaluation of proactive compression therapy in practice. The study results contribute to understanding the working mechanisms of IPC and improving its functional design based on intuitive biomechanical characteristics of compression delivery profiles.

A pilot study of venous flow augmentation using a novel mechanical graded intermittent sequential compression device for venous insufficiency

BACKGROUND

Guidelines as well as multiple RTCs support the use of intermittent pneumatic compression (IPC) for the treatment of venous leg ulcers when conservative measures fail. Unfortunately, the clinical usefulness of IPC is significantly limited by the physical limitations of pneumatic motors, which leads to bulky devices with slow inflation cycles, uncomfortable sleeves, lack of patient mobility, and ultimately poor patient compliance with therapy. A novel mechanical device for lower leg graded intermittent sequential compression was designed to address these limitations of IPC therapy for venous leg ulcer treatment by providing rapid compression cycles in a truly wearable device that offers the additional benefit of monitoring compression dose and patient compliance. The wearable intermittent compression (WIC) device was hypothesized to provide improved augmentation of venous flow compared with both baseline and standard IPC therapy.

METHODS

Ten patients with Clinical, Etiologic, Anatomic and Pathophysiologic class 3 to 6 venous insufficiency were recruited under institutional review board approval. The primary end point for the study was augmentation of venous blood flow as measured by peak venous velocity. Patients underwent measurement of peak venous velocity in centimeters per second at the popliteal and femoral veins for the following conditions: (1) baseline, (2) WIC device on a low setting, and (3) WIC device on a high setting. In five patients, an additional measurement of peak venous velocity in centimeters per second at the popliteal and femoral veins was completed while wearing a commercially available IPC device.

RESULTS

Both low and high settings of the WIC device resulted in higher average peak venous velocities when compared with both baseline and the IPC device (P < .05). No patients reported discomfort with either the WIC device or the IPC device during therapy.

CONCLUSIONS

The WIC device significantly increases the augmentation of venous flow as measured by peak venous velocity in both the popliteal and femoral veins in patients with Clinical, Etiologic, Anatomic and Pathophysiologic class 3 to 6 venous insufficiency. In addition, the WIC device was found to be easy to use and comfortable during therapy. Future studies are planned to determine if the WIC improvements in venous flow augmentation and patient compliance will lead to higher rates of venous ulcer healing.

Thromboelastographic changes during laparoscopic fundoplication

Introduction

Thromboelastography (TEG) is a technique that measures coagulation processes and surveys the properties of a viscoelastic blood clot, from its formation to lysis.

Aim

To determine the possible hypercoagulability state and the effect of antithrombotic prophylaxis on thromboelastogram results and development of venous thrombosis during laparoscopic fundoplication.

Material and methods

The study was performed on 106 patients who were randomized into two groups. The first group received low-molecular-weight heparin (LMWH) 12 h before the operation, and 6 and 30 h after it. The second group received LMWH only 1 h before the laparoscopic fundoplication. The TEG profile was collected before LMWH injection, 1 h after the introduction of the laparoscope and 15 min after the surgery was completed.

Results

There was no significant difference in thromboelastography R-time between the groups before low-molecular-weight heparin injection. In group I preoperative R-values significantly decreased 1 h after the introduction of the laparoscope, after the end of surgery and on the third postoperative day. K-time values decreased significantly on the third postoperative day compared with the results before low-molecular-weight heparin injection, and after the operation. In group II, preoperative R-values significantly decreased 1 h after the introduction of the laparoscope, and after surgery. K-time values did not change significantly during or after the laparoscopic operation.

Conclusions

Our study results demonstrated that the hypercoagulation state (according to the TEG results) was observed during and after laparoscopic fundoplication in patients when LMWH was administered 12 h before the operation together with intraoperative intermittent pneumatic compression. The optimal anticoagulation was obtained when LMWH was administered 1 h before fundoplication.

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.

Running Performance While Wearing a Heat Dissipating Compression Garment in Male Recreational Runners

Leoz-Abaurrea, I, Santos-Concejero, J, Grobler, L, Engelbrecht, L, and Aguado-Jiménez, R. Running performance while wearing a heat dissipating compression garment in male recreational runners. J Strength Cond Res 30(12): 3367-3372, 2016-The aim of this study was to investigate the effects of a heat dissipating compression garment (CG) during a running performance test. Ten male recreational runners (mean ± SD: age 23 ± 3 years; V[Combining Dot Above]O2max 55.8 ± 4.8 ml·kg·min) completed 2 identical sessions wearing either CG or conventional t-shirt (CON). Each trial included a 45-minute run at 60% of the peak treadmill speed (PTS) followed by a time to exhaustion (TTE) run at 80% of the PTS and a 10-minute recovery period. During the tests, thermoregulatory and cardiovascular responses were monitored. Participants wearing the CG displayed an impaired running performance (508 ± 281 vs. 580 ± 314 seconds, p = 0.046; effect size [ES] = 0.24). In addition, a higher respiratory exchange ratio (1.06 ± 0.04 vs. 1.02 ± 0.07, p = 0.01; ES = 0.70) was observed at TTE when wearing the CG in comparison to CON. Changes in core temperature did not differ between garments after the 45-minute run (p = 0.96; ES = 0.03) or TTE (1.97 ± 0.32 vs. 1.98 ± 0.38° C; p = 0.93; ES = 0.02) for CG and CON, respectively. During recovery, significantly higher heart rate and blood lactate values were observed when wearing CG (p ≤ 0.05). These findings suggest that the use of a heat dissipating CG may not improve running performance in male recreational runners during a running performance test to exhaustion.

A reduced-order model-based study on the effect of intermittent pneumatic compression of limbs on the cardiovascular system

This work investigates the effect that the application of intermittent pneumatic compression to lower limbs has on the cardiovascular system. Intermittent pneumatic compression can be applied to subjects with reduced or null mobility and can be useful for therapeutic purposes in sports recovery, deep vein thrombosis prevention and lymphedema drainage. However, intermittent pneumatic compression performance and the effectiveness are often difficult to predict. This study presents a reduced-order numerical model of the interaction between the cardiovascular system and the intermittent pneumatic compression device. The effect that different intermittent pneumatic compression operating conditions have on the overall circulation is investigated. Our findings confirm (1) that an overall positive effect on hemodynamics can be obtained by properly applying the intermittent pneumatic compression device and (2) that using intermittent pneumatic compression for cardiocirculatory recovery is feasible in subjects affected by lower limb disease.

Effectiveness of Intermittent Pneumatic Compression Devices for Venous Thromboembolism Prophylaxis in High-Risk Surgical Patients: A Systematic Review

BACKGROUND

Thromboprophylaxis regimens include pharmacologic and mechanical options such as intermittent pneumatic compression devices (IPCDs). There are a wide variety of IPCDs available, but it is uncertain if they vary in effectiveness or ease of use. This is a systematic review of the comparative effectiveness of IPCDs for selected outcomes (mortality, venous thromboembolism [VTE], symptomatic or asymptomatic deep vein thrombosis, major bleeding, ease of use, and adherence) in postoperative surgical patients.

METHODS

We searched MEDLINE (via PubMed), Embase, CINAHL, and Cochrane CENTRAL from January 1, 1995, to October 30, 2014, for randomized controlled trials, as well as relevant observational studies on ease of use and adherence.

RESULTS

We identified 14 eligible randomized controlled trials (2633 subjects) and 3 eligible observational studies (1724 subjects); most were conducted in joint arthroplasty patients. Intermittent pneumatic compression devices were comparable to anticoagulation for major clinical outcomes (VTE: risk ratio, 1.39; 95% confidence interval, 0.73-2.64). Limited data suggest that concurrent use of anticoagulation with IPCD may lower VTE risk compared with anticoagulation alone, and that IPCD compared with anticoagulation may lower major bleeding risk. Subgroup analyses did not show significant differences by device location, mode of inflation, or risk of bias elements. There were no consistent associations between IPCDs and ease of use or adherence.

CONCLUSIONS

Intermittent pneumatic compression devices are appropriate for VTE thromboprophylaxis when used in accordance with current clinical guidelines. The current evidence base to guide selection of a specific device or type of device is limited.

A Current Review of Mechanical Compression and Its Role in Venous Thromboembolic Prophylaxis in Total Knee and Total Hip Arthroplasty

Interest in mechanical compression for venous thromboembolic disease prophylaxis has increased over the last several years because of concerns related to bleeding complications associated with chemoprophylaxis. However, the research evaluating compression is clearly not definitive. Therefore, this review aims to: (1) summarize methods of compression; (2) compare AAOS, ACCP, and SCIP guidelines; and (3) make recommendations regarding usage. Below-the-knee devices have demonstrated the most efficacy with multiple guidelines recommending usage. Efficacy and compliance may be improved with the use of mobile devices.

The efficacy of intermittent pneumatic compression in the prevention of lower extremity deep venous thrombosis

Intermittent pneumatic compression (IPC) has been used to prevent lower extremity deep venous thrombosis for more than 30 years and is a popular choice for prophylaxis among both physicians and patients because of its efficacy and reduced risk of bleeding compared with pharmacologic prophylaxis. However, the efficacy of IPC may depend on the clinical situation as well as on several variables associated with the devices. To determine the efficacy of IPC, recent guidelines and literature were reviewed. IPC is efficacious as a sole prophylactic agent in low- or moderate-risk surgical patients and in patients with high risk of bleeding with pharmacologic prophylaxis. In high-risk surgical and medical patients, IPC is recommended as a synergistic tool in combination with pharmacologic agents, if pharmacologic agents are not contraindicated. No specific compression modality proved its superiority, although newer portable battery-powered devices seem to allow better patient compliance and satisfaction.

Comparison of clinical and physiological efficacies of different intermittent sequential pneumatic compression devices in preventing deep vein thrombosis: a prospective randomized study

BACKGROUND

There are few comparative studies about the optimal method of pneumatic compression to prevent deep vein thrombosis (DVT). The aim of this prospective randomized study was to compare venous hemodynamic changes and their clinical influences between two graded sequential compression groups (an alternate sequential compression device [ASCD] vs. a simultaneous sequential compression device [SSCD]).

METHODS

In total, 34 patients (68 limbs) undergoing knee and spine operations were prospectively randomized into two device groups (ASCD vs. SSCD groups). Duplex ultrasonography examinations were performed on the 4th and 7th postoperative days for the detection of DVT and the evaluation of venous hemodynamics. Continuous data for the two groups were analyzed using a two-tailed, unpaired t-test. Relative frequencies of unpaired samples were compared using Fisher exact test. Mixed effects models that might be viewed as ANCOVA models were also considered.

RESULTS

DVT developed in 7 patients (20.6%), all of whom were asymptomatic for isolated calf DVTs. Two of these patients were from the ASCD group (11.8%) and the other five were from the SSCD group (29.4%), but there was no significant difference (p = 0.331). Baseline peak velocity, mean velocity, peak volume flow, and total volume flow were enhanced significantly in both device groups (p < 0.001). However, the degrees of flow and velocity enhancement did not differ significantly between the groups. The accumulated expelled volumes for an hour were in favor of the ASCD group.

CONCLUSIONS

Both graded sequential compression devices showed similar results both in clinical and physiological efficacies. Further studies are required to investigate the optimal intermittent pneumatic compression method for enhanced hemodynamic efficacy and better thromboprophylaxis.

The post-thrombotic syndrome and compression therapy

Compression therapy is still the cornerstone in the treatment of PTS. The therapy is primarily focused on the decrease of the AVP, enhancement of the microcirculation and reduction of the edema. In our practice, most patients are initially treated with short stretch bandage to reduce the edema. Medical Elastic Compression Stockings (MECS) class II (CEN 23–32 mm Hg)or class III (CEN 34–46 mm Hg) with a high stiffness index are prescribed after the edema is disappeared. The prescription will be for a lifelong usage of stockings. Correction of saphenous reflux, deobstructing and stenting might be considered in certain patients with PTS.

A model-based method for the design of intermittent pneumatic compression systems acting on humans

Intermittent pneumatic compression is a well-known technique, which can be used for several therapeutic treatments like sports recovery, lymphoedema drainage, deep vein thrombosis prevention or others, which may require very different operating characteristics as regards the desired pressure values and the operating velocity. The performance and the effectiveness of the device are often difficult to predict and must be usually optimized through empirical adjustments. This article presents a general method based on the mathematical modelling of a generic IPC system, aimed at studying and developing such a device with physical and dynamical characteristics suitable for the intended application.

Upper body exercise increases lower extremity venous blood flow in deep venous thrombosis

OBJECTIVE

Sequential compression devices or ambulation prevent deep venous thrombosis (DVT) by enhancing venous blood flow in the lower extremity. However, compression therapy or ambulation may not be possible in patients with lower extremity surgery or trauma. We therefore determined whether upper body exercise increases venous blood flow in the lower extremities as a potential means for preventing DVT.

METHODS

We determined blood volume flow and velocity responses in the common femoral veins to low-intensity (5 W, 75 rpm) upper body cycle ergometry in healthy individuals. Six protocols of single and intermittent bouts of exercise were tested. Upon determination of the most efficacious protocol in these participants, we verified the effects of upper body exercise in patients with acute DVT. Measurements were made before, during, and after exercise using duplex ultrasound imaging.

RESULTS

The study enrolled 15 healthy volunteers (10 men, 5 women; aged 20-40 years) with no history of DVT and 10 patients (aged 31-86 years) with acute DVT. In healthy participants, a single 30-second bout of upper body exercise increased volume flow up to 39% for up to 10 minutes after exercise (P < .05). A single 3-minute bout increased flow to a lesser extent (23% increase; P = .05) for nearly 5 minutes, but a single 1-minute bout did not increase flow. An intermittent protocol of three 30-second bouts of exercise resulted in an increase of 34% to 57% in venous flow (P < .05) for an average increase of 179 ± 53 mL/min. Intermittent 1-minute bouts of exercise tended to increase flow 10% to 40% (P = .06-.08) for an average increase of 149 ± 64 mL/min. Intermittent 3-minute bouts of exercise increased flow 21% to 45% (P < .05) for an average increase of 120 ± 42 mL/min. In patients with acute DVT, the intermittent 30-second upper body exercise protocol increased venous blood flow by 45% to 83% (P < .05) for an average increase of 250 ± 63 mL/min, an effect lasting >13 minutes.

CONCLUSIONS

We report the novel finding that upper body exercise increases lower extremity venous blood flow in healthy volunteers and in acute DVT patients. Three intermittent 30-second bouts of low-intensity upper body exercise elicited the highest response for the least amount of effort and may represent an alternative or adjunct for prophylaxis of DVT in patients with restricted ambulation.

Intermittent pneumatic compression: physiologic and clinical basis to improve management of venous leg ulcers

Venous leg ulcers (VLUs) are a significant health problem that afflicts 1% of the population at some point during their lifetime. Intermittent pneumatic compression (IPC) is widely used to prevent deep venous thrombosis. However, IPC seems to have application to a broader base of circulatory diseases. The intermittent nature of pulsatile external compression produces beneficial physiologic changes, which include hematologic, hemodynamic, and endothelial effects, which should promote healing of VLUs. Clinical studies of the management of VLUs show that IPC increases overall healing and accelerates the rate of healing, leading to current guideline recommendations for care of patients with VLUs. Proper prescription of IPC to improve the management of patients with VLUs requires further definition. It seems that application of IPC in combination with sustained graduated compression improves outcome in patients with the most advanced venous disease.

A randomized blinded comparison of two methods used for venous antistasis in tetraplegia

OBJECTIVE

The hemodynamic effects of slow sequential compression (SCD) were compared with rapid intermittent pulsatile compression (IPC) in subjects with complete tetraplegia.

METHODS

Twenty subjects underwent Doppler examination of the bilateral popliteal and femoral veins. Resting volume flow per minute (VFM), average venous velocity (AVV), and maximal venous velocity (MVV) were measured in both veins. SCD and IPC were then randomly applied to one limb each, followed by repeat Doppler measurements under compression conditions. Doppler spectral recordings were stored for future analysis, and then measured by an investigator blinded to testing conditions (rest versus compression) and device (SCD versus IPC).

RESULTS

Sequential compression and IPC compression both increased popliteal and femoral vein VFM, AVV, and MVV above resting levels (all p's < 0.001). In the femoral vein VFM (p < 0.05) and MVV (p < 0.05) were augmented during IPC compared to SCD compression.

CONCLUSION

As MVV best reflects performance effectiveness of compression devices, these data find IPC more effective than SCD for stimulating venous blood flow in subjects with tetraplegia.

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.

Use of intermittent pneumatic compression in the treatment of venous ulcers

Venous ulcers affect up to 1% of the population. This review provides the hemodynamic, hematologic and clinical effects of intermittent pneumatic compression (IPC) in the treatment of venous ulcers. It presents the different IPCs and their application on venous disease. It points out that a large randomized study on IPC versus standard four-layer compression in the treatment of venous ulcers is needed. The cost–effectiveness of IPC in the treatment of venous ulcers should also be assessed.

Intermittent pneumatic compression regulates expression of nitric oxide synthases in skeletal muscles

This study investigated the effects of intermittent pneumatic compression (IPC) on expression of nitric oxide synthase (NOS) isoforms in compressed (anterior tibialis, AT) and uncompressed (cremaster muscles, CM) skeletal muscles. Following IPC application of 0.5, 1, and 5h on both legs of rats, the endothelial NOS (eNOS) mRNA expression was significantly up-regulated to 1.2-, 1.8, and 2.7-fold from normal, respectively, in both AT and CM, and protein expression increased more than 1.5-fold of normal at each time point. Similarly, neuronal NOS expression was up-regulated, but to a lesser degree. In contrast, inducible NOS expression was significantly and time-dependently down-regulated in both muscles. After IPC cessation, eNOS levels returned to normal in both AT and CM. The results confirm our hypothesis that IPC-induced vasodilation is mediated by regulating expression of NOS isoforms, in particular eNOS, in both compressed and uncompressed skeletal muscles. The results also suggest the importance of precisely characterizing expression of each NOS isoform in tissue pathophysiology.

Hemodynamic effects of intermittent pneumatic compression in patients with critical limb ischemia

BACKGROUND

Traditional teaching assumes that the distal arterial tree is maximally dilated in patients with critical limb ischemia (CLI). Endovascular or arterial bypass procedures are the commonly used interventions to increase distal perfusion. However, other forms of treatment such as spinal cord stimulation or intermittent pneumatic compression (IPC) have been shown to improve limb salvage rates. This prospective study was designed to determine if the use of IPC increases popliteal, gastrocnemial, collateral arterial, and skin blood flow in patients with CLI.

METHODS

Twenty limbs with CLI in 20 patients (mean age, 74 years) were evaluated with duplex ultrasound scans and laser Doppler fluxmetry in the semi-erect position before, during, and after IPC. One pneumatic cuff was applied on the foot and the other on the calf. The maximum inflation pressure was 120 mm Hg and was applied for 3 seconds at three cycles per minute. All patients had at least two-level disease by arteriography. Fourteen limbs were characterized as inoperable, and six were considered marginal for reconstruction. Flow volumes were measured in the popliteal, medial gastrocnemial, and a genicular collateral artery. Skin blood flux was measured on the dorsum of the foot at the same time.

RESULTS

Significant flow increase during the application of IPC was found in all three arteries (18/20 limbs) compared with baseline values (P < .02). The highest change was seen in the popliteal, followed by the gastrocnemial and the collateral artery. After the cessation of IPC, the flow returned to baseline. This was attributed to the elevation of time average velocity, as the diameter of the arteries remained unchanged. The skin blood flux increased significantly as well (P < .03). In the two limbs without an increase in the arterial or skin blood flow, significant popliteal vein reflux was found. Both limbs were amputated shortly after.

CONCLUSIONS

IPC increases axial, muscular, collateral, and skin blood flow in patients with CLI and may be beneficial to those who are not candidates for revascularization. Patients with significant venous reflux may not benefit from IPC. This supports the theory that one of the mechanisms by which IPC enhances flow is by increasing the arteriovenous pressure gradient.

Evidence-based compression: prevention of stasis and deep vein thrombosis

OBJECTIVE

To summarize the currently published scientific evidence for the venous flow effects of mechanical devices, particularly intermittent pneumatic compression, and the relation to prevention of deep vein thrombosis (DVT).

SUMMARY BACKGROUND DATA

While intermittent pneumatic compression is an established method of DVT prophylaxis, the variety of systems that are available can use very different compression techniques and sequences. In order for appropriate choices to be made to provide the optimum protection for patients, the general performance of systems, and physiological effects of particular properties, must be analyzed objectively.

METHODS

Medline was searched from 1970 to 2002, and all relevant papers were searched for further appropriate references. Papers were selected for inclusion when they addressed specifically the questions posed in this review.

RESULTS

All the major types of intermittent compression systems are successful in emptying deep veins of the lower limb and preventing stasis in a variety of subject groups. Compression stockings appear to function more by preventing distension of veins. Rapid inflation, high pressures, and graded sequential intermittent compression systems will have particular augmentation profiles, but there is no evidence that such features improve the prophylactic ability of the system.

CONCLUSIONS

The most important factors in selecting a mechanical prophylactic system, particularly during and after surgery, are patient compliance and the appropriateness of the site of compression. There is no evidence that the peak venous velocity produced by a system is a valid measure of medical performance.

Evaluation of intermittent pneumatic compression systems

The operational characteristics of eight intermittent pneumatic compression systems were evaluated. Considerable differences between the pressure/time curves were found when different pumps were compared. The pressure attained in the garments varied from 6 to 124 mmHg and the rate of inflation from less than 1 to 9 mmHg per second.

Role of nitric oxide in vasodilation in upstream muscle during intermittent pneumatic compression

This study investigated the dosage effects of nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on intermittent pneumatic compression (IPC)-induced vasodilation in uncompressed upstream muscle and the effects of IPC on endothelial NOS (eNOS) expression in upstream muscle. After L-NMMA infusion, mean arterial pressure increased by 5% from baseline (99.5 +/- 18.7 mmHg; P < 0.05). Heart rate and respiratory rate were not significantly affected. One-hour IPC application on legs induced a 10% dilation from baseline in 10- to 20-microm arterioles and a 10-20% dilation in 21- to 40 microm arterioles and 41- to 70-microm arteries in uncompressed cremaster muscle. IPC-induced vasodilation was dose dependently reduced, abolished, or even reversed by concurrently infused L-NMMA. Moreover, expression of eNOS mRNA in uncompressed cremaster muscle was upregulated to 2 and 2.5 times normal at the end of 1- and 5-h IPC on legs, respectively, and the expression of eNOS protein was upregulated to 1.8 times normal. These increases returned to baseline level after cessation of IPC. The results suggest that eNOS plays an important role in regulating the microcirculation in upstream muscle during IPC.

Nonpharmacologic thromboembolic prophylaxis in total knee arthroplasty

Deep venous thrombosis is the most common complication in patients having elective total knee replacement. Pneumatic compression devices play an important role in the prophylaxis of deep venous thrombosis and effectively decrease the risk of distal deep venous thrombosis. The combination therapy with pharmacologic agents has the benefit of decreasing the rate of proximal deep venous thrombosis and therefore is recommended. In the absence of clinical data, recent in vivo flow studies suggest that calf or combined foot and calf compression are superior to foot compression alone. Epidural anesthesia in comparison with general anesthesia decreases the incidence of thromboembolic disease after total knee arthroplasty. Although hypotensive anesthesia and intraoperative heparin have been proven to substantially lower the incidence of deep venous thrombosis after total hip arthroplasty, the current literature does not support its application during the implantation of a total knee replacement. Pneumatic compression devices are an important part of deep venous thrombosis prophylaxis especially in the early postoperative period considering that pharmacologic anticoagulation is contraindicated in the first 12 hours after spinal anesthesia and in the presence of an epidural line.

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

PURPOSE

A new intermittent pneumatic compression device (SCD Response System) has recently been shown in healthy volunteers to have the ability to detect the postcompression refilling of the calf veins and to respond by initiating the subsequent cycle when these veins are full. This has proven to be more effective in expelling blood proximally than the conventional intermittent pneumatic compression device (SCD Sequel System). The aim of this study was to test the influence of venous disease on the postcompression refill time detected by means of the SCD Response and the effectiveness of the new system in expelling blood in patients who have venous reflux caused by post-thrombotic syndrome or varicose veins.

METHODS

This open, controlled trial was conducted in an academic vascular unit with 10 patients who had post-thrombotic syndrome and 10 patients who had varicose veins. The new SCD Response System was tested against the existing SCD Sequel System in both legs in the supine, semirecumbent, and sitting positions. The refilling time sensed by means of the device was correlated with the venous filling index by using air plethysmography. The total volume of blood expelled per hour during compression was compared with that expelled by the SCD Sequel System in the same volunteers and in the same positions.

RESULTS

An inverse association was found between the mean postcompression refilling time in the sitting position and the venous filling index of the apparently healthy or less severely affected leg (r = -0.52, P =.019), the refill time being significantly shorter in patients with advanced venous disease. The SCD Response System increased the volume expelled per hour in the post-thrombotic leg, when compared with the SCD Sequel System, by 109.9% (P =.005) in the supine position, by 85.1% (P =.009) in the semirecumbent position, and by 40.2% (P =.005) in the sitting position. The corresponding results in the more severely affected leg in patients with varicose veins were 71.9% (P =.005) in the supine position, 77.9% (P =.005) in the semirecumbent position, and 55.7% (P =.013) in the sitting position. Similar improved results were also found in the contralateral leg in both groups.

CONCLUSIONS

The deflation settings of the new SCD Response System are able to be adjusted selectively, correlating with the physiological severity of chronic venous insufficiency. By achieving more frequent compression cycles, the new system is more effective than the current one in expelling blood proximally, confirming our earlier findings in healthy volunteers. Further studies testing a possible improved efficacy in preventing deep venous thrombosis in this high-risk group are justified.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The efficacy of the new SCD response compression system in the prevention of venous stasis

OBJECTIVE

The current commercially available sequential intermittent pneumatic compression device used for the prevention of deep venous thrombosis has a constant cycle of 11 seconds' compression and 60 seconds' deflation. This deflation period ensures that the veins are filled before the subsequent cycle begins. It has been suggested that in some positions (eg, semirecumbent or sitting) and with different patients (eg, those with venous reflux), refilling of the veins may occur much earlier than 60 seconds, and thus a more frequent cycle may be more effective in expelling blood proximally. The aim of the study was to test the effectiveness of a new sequential compression system (the SCD Response Compression System), which has the ability to detect the change in the venous volume and to respond by initiating the subsequent cycle when the veins are substantially full.

METHODS

In an open controlled trial at an academic vascular laboratory, the SCD Response Compression System was tested against the existing SCD Sequel Compression System in 12 healthy volunteers who were in supine, semirecumbent, and sitting positions. The refilling time sensed by the device was compared with that determined from recordings of femoral vein flow velocity by the use of duplex ultrasound scan. The total volume of blood expelled per hour during compression was compared with that produced by the existing SCD system in the same volunteers and positions.

RESULTS

The refilling time determined automatically by the SCD Response Compression System varied from 24 to 60 seconds in the subjects tested, demonstrating individual patient variation. The refilling time (mean +/- SD) in the sitting position was 40.6 +/- 10. 0 seconds, which was significantly longer (P <.001) than that measured in the supine and semirecumbent positions, 33.8 +/- 4.1 and 35.6 +/- 4.9 seconds, respectively. There was a linear relationship between the duplex scan-derived refill time (mean of 6 readings per leg) and the SCD Response device-derived refill time (r = 0.85, P <. 001). The total volume of blood (mean +/- SD) expelled per hour by the existing SCD Sequel device in the supine, semirecumbent, and sitting positions was 2.23 +/- 0.90 L/h, 2.47 +/- 0.86 L/h, and 3.28 +/- 1.24 L/h, respectively. The SCD Response device increased the volume expelled to 3.92 +/- 1.60 L/h or a 76% increase (P =.001) in the supine position, to 3.93 +/- 1.55 L/h or a 59% increase (P =. 001) in the semirecumbent position, and to 3.97 +/- 1.42 L/h or a 21% increase (P =.026) in the sitting position.

CONCLUSIONS

By achieving more appropriately timed compression cycles over time, the new SCD Response System is effective in preventing venous stasis by means of a new method that improves on the clinically documented effectiveness of the existing SCD system. Further studies testing its potential for improved efficacy in preventing deep venous thrombosis are justified.

Mechanisms of thrombosis in spinal cord injury

Many studies failed to identify a hypercoagulable imbalance in the blood factors or decreased anticoagulant activity. On the other hand, fibrinolysis, a process unrelated to hypercoagulability but closely related to endothelial cell integrity, is predictably altered and contributes to the persistence of venous occlusion by thrombosis. There is considerable evidence that interruption of neurologic impulses and the ensuing paralysis cause metabolic changes in blood vessels and that blood vessel changes are accountable for venous thrombosis. Altered venous competence with complete spinal cord injury manifests by a decrease in venous distensibility and capacity and an increase in venous flow resistance. Vascular adaptations to inactivity and muscle atrophy, rather than the effect of a nonworking leg-muscle pump and sympathetic denervation, seem to lead to the thrombosis; indicating that thrombosis resulting from venous incompetence cannot be reversed by anticoagulation alone.

Thrombosis risk in the trauma patient. Prevention and treatment

Hypercoagulability is frequently seen in the trauma patients. Debate continues over the best method of prophylaxis, diagnosis, and treatment for the trauma patient. From experience with orthopedic and general surgery patients, much has been learned about prophylaxis and diagnosis, and as treatment protocols have been taken from internal medicine literature. Universal guidelines relating specifically to the trauma patient have not, however, been established. Overall, most of the literature suggests using LMWH for the prophylaxis of trauma patients. When LMWH is contraindicated, SCD should be used, with AVFP as a second choice. Surveillance screening for DVT remains controversial, but surveillance before transfer to extended care facilities has proven beneficial. Finally, when DVT is diagnosed, treatment should be initiated as soon as possible and should be continued until the DVT has resolved. Long-term anticoagulation therapy or use of caval filters may be necessary to prevent the morbidity of PE or thrombophlebitic syndrome.

Intermittent pneumatic compression on the calf improves peripheral circulation of the leg

PURPOSE

The aim of this study was to examine whether intermittent pneumatic compression (IPC) increases peripheral circulation locally in order to assess the use of IPC for prevention of deep venous thrombosis.

MATERIALS AND METHODS

Seventy adult patients receiving major gastrointestinal surgery were studied. On postoperative day 1, calf-length garments were fitted onto both calves and deep temperature thermometers were put on both plantae. The IPC was applied randomly to either the left or right calf under 40 mm Hg pressure for 150 minutes. Bilateral plantar deep temperatures, as a reflection of peripheral circulation in the lower extremity, the tympanic temperature, mean blood pressure, and heart rate were recorded at 15-minute intervals.

RESULTS

IPC compression was applied to 31 left and 39 right calves. The plantar deep temperature in the compressed calf was higher than in the noncompressed calf, and increased significantly, whereas the noncompressed calf showed no temperature change. The tympanic temperature, mean blood pressure, and heart rate did not change during the experiment.

CONCLUSIONS

The results suggest that IPC has the effect of improving peripheral circulation, which supports the use of IPC to prevent deep venous thrombosis.