Intermittent pneumatic foot compression can activate blood fibrinolysis without changes in blood coagulability and platelet activation

Randomized Trial of Sequential Compression Versus Ankle-Calf Movement to Increase Femoral Venous Velocity

Objective In postoperative patients with a high risk of bleeding, sequential compression devices (SCD) and ambulation are effective methods to reduce venous thromboembolic (VTE) risks. High leg venous flow decreases VTE risk. We postulated that ankle flexion and extension (AFE) while in bed increased leg venous flow velocity as well. We wished to compare the effectiveness of SCD versus AFE in increasing leg venous velocity. Methods Thirty-two healthy volunteers were recruited into the study. Each subject had two legs that were randomized into SCD or AFE. After 15 minutes of rest, SCD or AFE was applied, followed by 15 minutes of rest, and then an alternate treatment was given to the second leg. The sequence of leg and methodology was then reversed so the second treatment was applied to the first leg, and the first treatment to the second leg, and measurements were obtained. All treatments were separated by a rest period of 15 minutes. The venous velocity on each leg was measured by Doppler ultrasound at the superficial femoral vein. Venous velocity was measured initially (first cycle peak venous velocity) and during subsequent cycles. The alternate treatments on both legs with both treatments allowed for analysis in a manner where each subject could act as its control. Results Relative to baseline bed rest, SCD increased peak venous flow velocity by 112%, while AFE increased peak venous flow velocity by 161%. AFE resulted in 43% higher venous velocity on average than did SCDs (p<0.05). Conclusions AFE leads to significantly higher venous flow in the femoral veins of healthy subjects.

Blood flow restriction as a potential therapy to restore physical function following COVID-19 infection

Accumulating evidence indicates that some COVID-19 survivors display reduced muscle mass, muscle strength, and aerobic capacity, which contribute to impairments in physical function that can persist for months after the acute phase of illness. Accordingly, strategies to restore muscle mass, muscle strength, and aerobic capacity following infection are critical to mitigate the long-term consequences of COVID-19. Blood flow restriction (BFR), which involves the application of mechanical compression to the limbs, presents a promising therapy that could be utilized throughout different phases of COVID-19 illness. Specifically, we hypothesize that: 1) use of passive BFR modalities can mitigate losses of muscle mass and muscle strength that occur during acute infection and 2) exercise with BFR can serve as an effective alternative to high-intensity exercise without BFR for regaining muscle mass, muscle strength, and aerobic capacity during convalescence. The various applications of BFR may also serve as a targeted therapy to address the underlying pathophysiology of COVID-19 and provide benefits to the musculoskeletal system as well as other organ systems affected by the disease. Consequently, we present a theoretical framework with which BFR could be implemented throughout the progression from acute illness to outpatient rehabilitation with the goal of improving short- and long-term outcomes in COVID-19 survivors. We envision that this paper will encourage discussion and consideration among researchers and clinicians of the potential therapeutic benefits of BFR to treat not only COVID-19 but similar pathologies and cases of acute critical illness.

Fibrinolysis Regulation: A Promising Approach to Promote Osteogenesis

Soon after bone fracture, the initiation of the coagulation cascade results in the formation of a blood clot, which acts as a natural material to facilitate cell migration and osteogenic differentiation at the fracture site. The existence of hematoma is important in early stage of bone healing, but the persistence of hematoma is considered harmful for bone regeneration. Fibrinolysis is recently regarded as a period of critical transition in angiogenic-osteogenic coupling, it thereby is vital for the complete healing of the bone. Moreover, the enhanced fibrinolysis is proposed to boost bone regeneration through promoting the formation of blood vessels, and fibrinolysis system as well as the products of fibrinolysis also play crucial roles in the bone healing process. Therefore, the purpose of this review is to elucidate the fibrinolysis-derived effects on osteogenesis and summarize the potential approaches-improving bone healing by regulating fibrinolysis, with the purpose to further understand the integral roles of fibrinolysis in bone regeneration and to provide theoretical knowledge for potential fibrinolysis-related osteogenesis strategies. Impact statement Fibrinolysis emerging as a new and viable therapeutic intervention to be contained within osteogenesis strategies, however to now, there have been no review articles which collates the information between fibrinolysis and osteogenesis. This review, therefore, focusses on the effects that fibrinolysis exerts on bone healing, with a purpose to provide theoretical reference to develop new strategies to modulate fibrinolysis to accelerate fibrinolysis thus enhancing bone healing.

Sequential Pneumatic Compression in the Arm in Neurocritical Patients with a Peripherally Inserted Central Venous Catheter: A Randomized Trial

BACKGROUND

Peripherally inserted central venous catheters (PICCs) are increasingly used for parenteral access in critically ill hospitalized patients, but they increase the incidence of upper extremity deep venous thrombosis (UE DVT). Sequential compression devices (SCDs) applied to the legs effectively reduce lower extremity DVT, but have not been tested in the arms. Our objective was to determine whether SCDs applied to the arm may reduce the risk of PICC-associated UE DVT.

METHODS

This was a retrospective study of randomized, single-center, controlled clinical trial on patients hospitalized in the intensive care unit with critical neurological illness who had a PICC and were not receiving anticoagulants. Between January 2014 and October 2016, patients were randomized 1:1 to an intervention group having a custom SCD applied to the arm harboring the PICC or to a control group. The primary endpoint was ultrasound-detected UE DVT.

RESULTS

Following randomization of 77 subjects, the study was terminated due to excess DVT in the treatment arm. UE DVT was detected in 18 subjects (29.0%), and it was more frequent among those in the SCD group (13/31 [41.9%] vs. the control group 5/31 [16.1%]; p = 0.049). After accounting for crossovers, the difference was still significant (12/28 [43.0%] vs. 6/34 [17.6%]; p = 0.048). Yet, symptomatic UE DVT (n = 3) and pulmonary embolism without evidence of lower extremity DVT (n = 2) were only observed in patients who were not wearing the SCD on the arm.

CONCLUSIONS

Although UE DVT is commonly associated with PICC use, the results of this trial do not support the use of SCD on the arm for DVT prevention. Further research on this strategy may nonetheless be justified.

TRIAL REGISTRATION

This trial was registered in ClinicalTrials.gov under the identifier NCT01670188.

Intense Triceps Surae Contraction Increases Lower Extremity Venous Blood Flow

Objective

Venous thromboembolism can be prevented by physical prophylaxis, such as active ankle exercise (AAE), in addition to pharmacological treatment. However, the relationship between the intensity of triceps surae (TS) exercise and venous flow is unclear, and physical thromboprophylaxis has not been established for patients with leg cast immobilization. The goals of the current study were to clarify the degree of intensity of TS isotonic contraction required to increase peak blood velocity (PV) in the superficial femoral vein to higher than that at no resistance and to determine if TS isometric contraction can increase PV.

Methods

A prospective, nonrandomized, controlled trial was performed in 20 healthy young adult men. PVs at rest and during one TS isotonic or isometric contraction were measured using Doppler ultrasonography. Isotonic contraction intensity was defined as no resistance with contraction of maximum effort and 25%, 50%, 75%, and 100% of one repetition maximum (1RM). Isometric contraction intensity was defined as 15-35%, 40-60%, 65-85%, and 90-100% of the maximal voluntary contraction.

Results

Isotonic contraction at 75% 1RM (51.4 cm/s [95% CI, 40.1-62.6]) and 100% 1RM (54.9 cm/s [95% CI, 43.1-66.7]) significantly increased PV compared to that with no resistance (41.0 cm/s [95% CI, 32.2-49.8]) (P=0.005, 0.001, respectively). Isometric contraction increased PV significantly at all intensities (all P≤0.002).

Conclusions

Applying resistance at ≥75% 1RM increases venous flow and enhances the effect of AAE with TS isotonic contraction. TS isometric contraction may serve as thromboprophylaxis for patients undergoing leg cast immobilization.

Electrical muscle stimulation in thomboprophylaxis: review and a derived hypothesis about thrombogenesis-the 4th factor

INTRODUCTION

Electrical muscle stimulation (EMS) is an FDA-approved thromboprophylactic method. Thrombus pathogenesis is considered to depend on factors related to components of the vessel wall, the velocity of blood, and blood consistency-collectively known as, the Virchow's triad.

OBJECTIVE

The testimony supporting the thromboprophylactic effects of the EMS is reviewed. An emphasis is placed on the fact that, EMS has demonstrated, in certain circumstances, an efficacy rate that cannot be fully explained by the Virchow's triad; also that, in reviewing relevant evidence and the theorized pathophysiological mechanisms, several findings collectively point to a potentially missed point. Remarkably, venous thromboembolic disease (VTE) is extremely more common in the lower versus the upper extremities even when the blood velocities equalize; EMS had synergistic effects with intermittent compressive devices, despite their presumed identical mechanism of action; sleep is not thrombogenic; non-peroperative EMS is meaningful only if applied ≥5 times daily; neural insult increases VTEs more than the degree expected by the hypomobility-related blood stasis; etc. These phenomena infer the presence of a 4th thrombogenetic factor: neural supply to the veins provides direct antithrombic effects, by inducing periodic vessel diameter changes and/or by neuro-humoral, chemically acting factors. EMS may stimulate or substitute the 4th factor. This evidence-based hypothesis is analyzed.

CONCLUSION

A novel pathophysiologic mechanism of thrombogenesis is supported; and, based on this, the role of EMS in thromboprophylaxis is expanded. Exploration of this mechanism may provide new targets for intervention.

The Clots in Legs Or sTockings after Stroke (CLOTS) 3 trial: a randomised controlled trial to determine whether or not intermittent pneumatic compression reduces the risk of post-stroke deep vein thrombosis and to estimate its cost-effectiveness

BACKGROUND

Venous thromboembolism (VTE) is a common cause of death and morbidity in stroke patients. There are few data concerning the effectiveness of intermittent pneumatic compression (IPC) in treating patients with stroke.

OBJECTIVES

To establish whether or not the application of IPC to the legs of immobile stroke patients reduced their risk of deep vein thrombosis (DVT).

DESIGN

Clots in Legs Or sTockings after Stroke (CLOTS) 3 was a multicentre, parallel-group, randomised controlled trial which allocated patients via a central randomisation system to IPC or no IPC. A technician blinded to treatment allocation performed compression duplex ultrasound (CDU) of both legs at 7-10 days and 25-30 days after enrolment. We followed up patients for 6 months to determine survival and later symptomatic VTE. Patients were analysed according to their treatment allocation.

SETTING

We enrolled 2876 patients in 94 UK hospitals between 8 December 2008 and 6 September 2012.

PARTICIPANTS

INCLUSION CRITERIA

patients admitted to hospital within 3 days of acute stroke and who were immobile on the day of admission (day 0) to day 3.

EXCLUSION CRITERIA

age < 16 years; subarachnoid haemorrhage; and contra-indications to IPC including dermatitis, leg ulcers, severe oedema, severe peripheral vascular disease and congestive cardiac failure.

INTERVENTIONS

Participants were allocated to routine care or routine care plus IPC for 30 days, or until earlier discharge or walking independently.

MAIN OUTCOME MEASURES

The primary outcome was DVT in popliteal or femoral veins, detected on a screening CDU, or any symptomatic DVT in the proximal veins, confirmed by imaging, within 30 days of randomisation. The secondary outcomes included death, any DVTs, symptomatic DVTs, pulmonary emboli, skin breaks on the legs, falls with injury or fractures and duration of IPC use occurring within 30 days of randomisation and survival, symptomatic VTE, disability (as measured by the Oxford Handicap Scale), quality of life (as measured by the European Quality of Life-5 Dimensions 3 Level questionnaire) and length of initial hospital stay measured 6 months after randomisation.

RESULTS

We allocated 1438 patients to IPC and 1438 to no IPC. The primary outcome occurred in 122 (8.5%) of 1438 patients allocated to IPC and 174 (12.1%) of 1438 patients allocated to no IPC, giving an absolute reduction in risk of 3.6% [95% confidence interval (CI) 1.4% to 5.8%] and a relative risk reduction of 0.69 (95% CI 0.55 to 0.86). After excluding 323 patients who died prior to any primary outcome and 41 who had no screening CDU, the primary outcome occurred in 122 of 1267 IPC participants compared with 174 of 1245 no-IPC participants, giving an adjusted odds ratio of 0.65 (95% CI 0.51 to 0.84; p = 0.001). Secondary outcomes in IPC compared with no-IPC participants were death in the treatment period in 156 (10.8%) versus 189 (13.1%) (p = 0.058); skin breaks in 44 (3.1%) versus 20 (1.4%) (p = 0.002); and falls with injury in 33 (2.3%) versus 24 (1.7%) (p = 0.221). Among patients treated with IPC, there was a statistically significant improvement in survival to 6 months (hazard ratio 0.86, 95% CI 0.73 to 0.99; p = 0.042), but no improvement in disability. The direct cost of preventing a DVT was £1282 per event (95% CI £785 to £3077).

CONCLUSIONS

IPC is an effective and inexpensive method of reducing the risk of DVT and improving survival in immobile stroke patients.

FUTURE RESEARCH

Further research should test whether or not IPC improves survival in other groups of high-risk hospitalised medical patients. In addition, research into methods to improve adherence to IPC might increase the benefits of IPC in stroke patients.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN93529999.

FUNDING

The start-up phase of the trial (December 2008-March 2010) was funded by the Chief Scientist Office of the Scottish Government (reference number CZH/4/417). The main phase of the trial was funded by the National Institute for Health Research Health Technology Assessment programme (reference number 08/14/03). Covidien Ltd (Mansfield, MA, USA) lent its Kendall SCD™ Express sequential compression system controllers to the 105 centres involved in the trial and donated supplies of its sleeves. It also provided logistical help in keeping our centres supplied with sleeves and training materials relevant to the use of their devices. Recruitment and follow-up were supported by the National Institute for Health Research-funded UK Stroke Research Network and by the Scottish Stroke Research Network, which was supported by NHS Research Scotland.

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.

The Prevention of Venous Thromboembolism in Surgical Patients

Patients undergoing surgery are at an increased risk of VTE. Since the early 1990s the prevention of VTE has been dominated by the administration of low-molecular weight heparin during admission. New oral anticoagulants have been extensively researched and have increased in popularity. This chapter reviews why surgical patients are at increased risk of VTE and summaries both the pharmacological and mechanical methods of prophylaxis available.

Causes of death among persons who survive an acute ischemic stroke

Stroke and especially its complications are a leading cause of death. Despite reduced morbidity in some developed countries, mortality in stroke patients is still high worldwide. In the past decades, treatment of acute stroke has focused on early intervention, such as revascularization and cerebral edema prevention. However, long-term clinical observations indicate that poststroke pneumonia, cardiovascular complications, and vascular embolism are the major reasons for the increased death rate after stroke. Few evidence-based data are available currently to guide the management of these complications. Thus, systematic studies of these adverse events are essential and urgent to improve survival after stroke.

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.

Effectiveness of intermittent pneumatic compression in reduction of risk of deep vein thrombosis in patients who have had a stroke (CLOTS 3): a multicentre randomised controlled trial

BACKGROUND

Venous thromboembolism is a common, potentially avoidable cause of death and morbidity in patients in hospital, including those with stroke. In surgical patients, intermittent pneumatic compression (IPC) reduces the risk of deep vein thrombosis (DVT), but no reliable evidence exists about its effectiveness in patients who have had a stroke. We assessed the effectiveness of IPC to reduce the risk of DVT in patients who have had a stroke.

METHODS

The CLOTS 3 trial is a multicentre parallel group randomised trial assessing IPC in immobile patients (ie, who cannot walk to the toilet without the help of another person) with acute stroke. We enrolled patients from day 0 to day 3 of admission and allocated them via a central randomisation system (ratio 1:1) to receive either IPC or no IPC. A technician who was masked to treatment allocation did a compression duplex ultrasound (CDU) of both legs at 7-10 days and, wherever practical, at 25-30 days after enrolment. Caregivers and patients were not masked to treatment assignment. Patients were followed up for 6 months to determine survival and later symptomatic venous thromboembolism. The primary outcome was a DVT in the proximal veins detected on a screening CDU or any symptomatic DVT in the proximal veins, confirmed on imaging, within 30 days of randomisation. Patients were analysed according to their treatment allocation.

TRIAL REGISTRATION

ISRCTN93529999.

FINDINGS

Between Dec 8, 2008, and Sept 6, 2012, 2876 patients were enrolled in 94 centres in the UK. The included patients were broadly representative of immobile stroke patients admitted to hospital and had a median age of 76 years (IQR 67-84). The primary outcome occurred in 122 (8·5%) of 1438 patients allocated IPC and 174 (12·1%) of 1438 patients allocated no IPC; an absolute reduction in risk of 3·6% (95% CI 1·4-5·8). Excluding the 323 patients who died before any primary outcome and 41 without any screening CDU, the adjusted OR for the comparison of 122 of 1267 patients vs 174 of 1245 patients was 0·65 (95% CI 0·51-0·84; p=0·001). Deaths in the treatment period occurred in 156 (11%) patients allocated IPC and 189 (13%) patients allocated no IPC died within the 30 days of treatment period (p=0·057); skin breaks on the legs were reported in 44 (3%) patients allocated IPC and in 20 (1%) patients allocated no IPC (p=0·002); falls with injury were reported in 33 (2%) patients in the IPC group and in 24 (2%) patients in the no-IPC group (p=0·221).

INTERPRETATION

IPC is an effective method of reducing the risk of DVT and possibly improving survival in a wide variety of patients who are immobile after stroke.

FUNDING

National Institute of Health Research (NIHR) Health Technology Assessment (HTA) programme, UK; Chief Scientist Office of Scottish Government; Covidien (MA, USA).

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.

Prevention of Deep Vein Thrombosis and Pulmonary Embolism in Patients With Stroke

Venous thromboembolism (VTE), encompassing deep venous thrombosis and pulmonary embolism, is a potentially fatal but preventable complication of stroke. Reported rates of VTE after stroke have decreased over the last four decades, possibly due to the implementation of stroke units, early mobilization and hydration, and increased early use of antiplatelets. Additional means of thromboprophylaxis in stroke include mechanical methods (ie, compression stockings) to prevent venous stasis and medical therapy including antiplatelets, heparins, and heparinoids. Risk of VTE must be balanced by potential risk of hemorrhagic complications from pharmacotherapy. Unfractionated heparin, low-molecular-weight heparin (LMWH), and danaparoid are acceptable options for chemoprophylaxis though none have shown superior efficacy for VTE prevention without an associated increase in major hemorrhage. The efficacy and timing of pharmacological thromboprophylaxis in hemorrhagic stroke are not well defined. Graduated compression stockings are associated with an increased rate of adverse events and are not recommended and intermittent pneumatic compression stockings require further investigation.

Physical methods for preventing deep vein thrombosis in stroke

BACKGROUND

Deep vein thrombosis (DVT) and resulting pulmonary embolism (PE) are important complications of stroke. Physical methods to reduce the risk of DVT and PE, such as graduated compression stockings (GCS) or intermittent pneumatic compression (IPC) applied to the legs, do not appear to be associated with any bleeding risk and reduce the risk of DVT in some categories of surgical patients. We sought to assess their effects in stroke patients.

OBJECTIVES

To assess the effectiveness and safety of physical methods of reducing the risk of DVT, fatal or non-fatal PE and death in patients with recent stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched November 2009), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2009), MEDLINE (1966 to November 2009), EMBASE (1980 to November 2009), CINAHL (1982 to November 2009) and The British Nursing Index (1985 to November 2009). We screened reference lists of all relevant papers, searched ongoing trials registers (November 2009) and contacted experts in the field.

SELECTION CRITERIA

Unconfounded randomised controlled trials comparing physical methods for reducing the risk of DVT with control and in which prophylaxis was started within seven days of the onset of stroke.

DATA COLLECTION AND ANALYSIS

Two review authors searched for trials and extracted data.

MAIN RESULTS

We identified two trials of GCS that included 2615 patients and two small studies of IPC that included 177 patients. Overall, physical methods were not associated with a significant reduction in DVTs during the treatment period (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.70 to 1.04) or deaths (OR 1.12, 95% CI 0.87 to 1.45). Use of GCS was not associated with any significant reduction in risk of DVT (OR 0.88, 95% CI 0.72 to 1.08) or death (OR 1.13, 95% CI 0.87 to 1.47) at the end of follow up. IPC was associated with a non-significant trend towards a lower risk of DVTs (OR 0.45, 95% CI 0.19 to 1.10) with no evidence of an effect on deaths (OR 1.04, 95% CI 0.37 to 2.89).

AUTHORS' CONCLUSIONS

Evidence from randomised trials does not support the routine use of GCS to reduce the risk of DVT after acute stroke. There is insufficient evidence to support the routine use of IPC to reduce the risk of DVT in acute stroke and further larger randomised studies of IPC are needed to reliably assess the balance of risks and benefits of this intervention.

Systemic hemodynamic effects of sequential pneumatic compression of the lower limbs: a prospective study in healthy volunteers

STUDY OBJECTIVE

To evaluate the effects on systemic hemodynamics of sequential pneumatic compression of the lower limbs in healthy volunteers.

DESIGN

Prospective, self-controlled, volunteer study.

SETTING

University teaching hospital.

PATIENTS

11 healthy volunteers, aged 25 +/- 1.3 years.

INTERVENTIONS AND MEASUREMENTS

After volunteers underwent a 6-hour period of fasting and 15 minutes of rest in the supine position, baseline systemic hemodynamics were assessed using transthoracic electrical bioimpedance. Peripheral venous pressure was measured using a 16-gauge intravenous cannula inserted in the forearm and connected to a pressure monitor. Then sequential pneumatic compression of the lower limbs was activated for a 30-minute period, and systemic hemodynamic measurements were repeated. In each volunteer, measurements were repeated twice in two consecutive days, and average values were calculated for each volunteer.

MAIN RESULTS

After activation of sequential pneumatic compression of the lower limbs, mean arterial blood pressure increased from 90 mmHg (79-107 mmHg) to 95 mmHg (79-129 mmHg) (P = 0.02), whereas heart rate decreased from 79 bpm (51-94 bpm) to 75 bpm (53-90 bpm) (P = 0.02). This was associated with a significant increase in peripheral vascular resistance index (from 545 [440-1066] to 613 [369-1280] dynes s cm(-5) m(-2) [P = 0.013]) and reduction in cardiac index (from 3.4 [2.7- 4.5] to 3.2 [2.5-4.0] L/min per m2 [P = 0.034]).

CONCLUSIONS

The application of sequential pneumatic compression to the lower limbs is associated with minor increases in mean arterial blood pressure, with moderate reduction of cardiac output and heart rate.