Intermittent Calf Compression Research Articles

Incidence of Symptomatic Venous Thromboembolism (VTE) in 8,885 Elective Total Hip Arthroplasty Patients Receiving Post-operative Aspirin VTE Prophylaxis.

Venous thromboembolism (VTE) is a potentially reducible cause of morbidity and mortality in patients undergoing elective hip arthroplasty surgery. The balance of post-operative VTE prophylaxis and risk of post-operative haemorrhage remains at the forefront of surgeon's mind. The National Institute for Health and Care Excellence (NICE) published updated guidelines in 2018 which recommend the use of both mechanical and pharmacological methods in patients undergoing elective total hip arthroplasty (THA). The aim of this study was to present the symptomatic VTE incidence in 8,885 patients who underwent THA between January 1998 and March 2018 with Aspirin as the primary agent for pharmacological thromboprophylaxis. Intermittent calf compression stockings are routinely used from the time of surgery until mobilization (usually the following day) with prophylactic doses of low molecular weight heparin (LMWH) during inpatient stay (from 2005 onwards) and then Aspirin 150mg once daily for six weeks on hospital discharge (or Aspirin only prior to 2005), with use of other therapies occasionally as required. Analysis of prospective data collection from consecutive patients at a single institution undergoing THA was performed with the incidence of symptomatic deep vein thrombosis (DVT) and pulmonary embolism (PE) occurring within six months of the index operation as the primary outcome measure. Ninety-day all-cause mortality of this cohort of patients was also analysed. 8,885 patients were reviewed. This included 7230 primary, 224 complex primary and 1431 revision cases. The overall incidence of symptomatic VTE after elective THA was 1.11% (99/8885) - with the incidence of symptomatic DVT of 0.59% (52/8885) and the incidence of symptomatic PE of 0.53% (47/8885). There was no significant difference (χ2 test, p=0.239) in the symptomatic VTE incidence between primary (1.20% - 89/7230), complex primary (0.89% - 2/224) and revision cases (0.70% - 10/1431). The 90-day all-cause mortality was 0.88% (78/8885). Cardiovascular and respiratory disease were the main causes of death following surgery. Only 0.03% of deaths (n= 3) within 90 days of index surgery were due to PE. There was no significant difference (p=0.327) in length of stay (and hence amount of pharmacologic prophylaxis with LMWH received by patients before commencement of Aspirin) with the average length of stay for those patients who did not suffer a VTE of 6.8 days compared with 7.6 days for those who did suffer a VTE. Our results support the use of aspirin as an effective form of prophylaxis against symptomatic VTE following THA in contradiction to NICE and American Academy of Orthopaedic Surgery (AAOS) recommendations. It is not associated with an increased incidence in symptomatic DVT, PE or death compared to other published studies. The fact that it is inexpensive, readily available, requires no monitoring and does not pose an increased risk of bleeding are other advantages of using aspirin for VTE prophylaxis.

Intermittent Calf Compression Delays the Onset of Presyncope in Young Healthy Individuals.

Orthostatic fluid shifts reduce the effective circulating volume and thus contribute to syncope susceptibility. Recurrent syncope has a devastating impact on quality of life and is challenging to manage effectively. To blunt orthostatic fluid shifts, static calf compression garments are often prescribed to patients with syncope, but have questionable efficacy. Intermittent calf compression, which mimics the skeletal muscle pump to minimize pooling and filtration, holds promise for the management of syncope. We aimed to evaluate the effectiveness of intermittent calf compression for increasing orthostatic tolerance (OT; time to presyncope). We conducted a randomized single-blind crossover study, in which participants (n = 21) underwent three graded 60° head-up-tilt tests to presyncope with combined lower body negative pressure on separate days. Low frequency intermittent calf compression (ICLF; 4 s on and 11 s off) at 0–30 and 0–60 mmHg was applied during two tests and compared to a placebo condition where the garment was fitted, but no compression applied. We measured continuous leg circumference changes (strain gauge plethysmography), cardiovascular responses (finger plethysmography; Finometer Pro), end tidal gases (nasal cannula), and cerebral blood flow velocity (CBFv, transcranial Doppler). The 0–60 mmHg ICLF increased OT (33 ± 2.2 min) compared to both placebo (26 ± 2.4 min; p < 0.001) and 0–30 mmHg ICLF (25 ± 2.7 min; p < 0.001). Throughout testing 0–60 mmHg ICLF reduced orthostatic fluid shifts compared to both placebo and 0–30 mmHg ICLF (p < 0.001), with an associated improvement in stroke volume (p < 0.001), allowing blood pressure to be maintained at a reduced heart rate (p < 0.001). In addition, CBFv was higher with 0–60 mmHg ICLF than 0–30 mmHg ICLF and placebo (p < 0.001). Intermittent calf compression is a promising novel intervention for the management of orthostatic intolerance, which may provide affected individuals renewed independence and improved quality of life.

Multimodal thromboprophylaxis in low-risk patients undergoing lower limb arthroplasty: A retrospective observational cohort analysis of 1400 patients with ultrasound screening.

This study reports the results of a multimodal thromboprophylaxis protocol for lower limb arthroplasty involving risk stratification, intraoperative calf compression, aspirin prophylaxis and early (within 4 h) post-operative mobilisation facilitated by the use of local infiltration analgesia. The study also aimed to identify risk factors for venous thromboembolism (VTE) within a 3-month period following surgery for patients deemed not at elevated risk. Patients undergoing knee/hip arthroplasty or hip resurfacing were preoperatively screened for VTE risk factors, and those at standard risk were placed on a thromboprophylaxis protocol consisting of intraoperative intermittent calf compression during surgery, 300 mg/day aspirin for 6 weeks from surgery and early mobilisation. Patients were screened bilaterally for deep vein thrombosis (DVT) on post-operative days 10-14. If proximal DVT was detected, patients were anticoagulated and outcomes were recorded. Symptomatic VTE within 3 months of surgery were recorded separately. Patient notes were retrospectively collated and cross-validated against ultrasound reports. At initial screening, the rate of proximal DVT was 0.54% (1.1% for knee and 0.27% for hip), and distal DVT was 6.63% (20.11% for knee and 2.31% for hip). One small, nonfatal pulmonary embolism (PE) was detected within 3 months of surgery (0.28% of total knee arthroplasty patients or 0.07% of total). All proximal DVTs were treated successfully with anticoagulants; however, one patient suffered a minor PE approximately 10 months post-operatively. Regression analysis identified knee implant and advanced age as independent risk factors for VTE in this cohort. Although knee arthroplasty patients remained at higher risk than hip replacement/resurfacing patients, the incidence and outcomes of VTE remained positive compared with protocols involving extended immobilisation, and episodes of PE were extremely rare. Thus, we conclude that patients at standard preoperative risk of VTE may safely be taken through the post-operative recovery process with a combination of intraoperative mechanical prophylaxis, early mobilisation and post-operative aspirin, with closer attention required for older patients and those undergoing knee surgery.

COT-20 PERIOPERATIVE STATUS OF SERUM D-DIMER LEVEL AND VENOUS THROMBOSIS IN PATIENTS WITH MALIGNANT BRAIN TUMOR

BACKGROUNDSThe patients with malignant brain tumors frequently show the hypercoagulability state and a decrease in fibrinolysis ability with an elevation in D-dimer. This is partially due to tumor-related hemiparesis or surgical stress including long-term bed-ridden positioning during and after operation,which could lead to development and extension of deep venous thrombosis (DVT) in lower extremities and eventually fatal pulmonary embolism.METHODSWe retrospectively examined the pre- and postoperative serum D-dimer levels and DVT state in 75 consecutive patients with malignant brain tumors (i.e. glioma,malignant lymphoma; mean age 64 yo,28 females) operated at our hospital from January 2015 to April 2017. Serial D-dimer levels were measured with the latex agglutination method (Roche) at 2 days before and right after operation,postoperative day (POD) 1,3,and 7. Lower limb venous ultrasound (LVUS) or contrast CT was performed if preoperative D-dimer was 0.5μg/ml or higher.RESULTSAverage BMI was 21.3,nine patients with diabetes mellitus,10 had recurrent diseases after chemotherapy,and 10 presented paresis in the lower extremities preoperatively while two developed transient paresis postoperatively. While two patients had prior DVT history,central and calf DVTs were identified preoperatively in one and 12 (15%) patients,respectively. Among four patients with re-elevation of D-dimer after POD 7,infection (2 patients),new DVT (2),and hemorrhagic events (gastrointestinal 2,including 1 death; epistaxis 2) developed,where a cut-off value D-dimer > 1.69 yielded sensitivity 100% and specificity 80%. Intraoperative intermittent calf compression prevented perioperative pulmonary embolism in those with calf DVT.CONCLUSIONSAppropriate perioperative DVT managements could prevent development of pulmonary embolisms in all patients with”high-risk” malignant brain tumors. Not only D-dimer > 1.5,but age of 80 or older,high preoperative D-dimer levels with calf DVT and taking DOAC may be risk factors for postoperative venous thromboembolism.

Intermittent calf compression reverses lower limb pooling and improves cardiovascular control during passive orthostasis.

When upright, venous pooling and capillary filtration reduce the effective circulating volume and are key contributors to susceptibility to syncope (fainting). Recurrent syncope has a devastating impact on quality of life. Static calf compression garments are frequently prescribed for patients with syncope, but have questionable efficacy. Intermittent calf compression, which mimics the skeletal muscle pump to minimize pooling and filtration, is a potential alternative that holds promise for the management of syncope. We aimed to evaluate use of intermittent calf compression compared to commonly prescribed compression stockings, and determine the optimal intermittent calf compression paradigm, for improvement of orthostatic fluid shifts and cardiovascular control. We evaluated heart rate, blood pressure, stroke volume, cardiac output and peripheral resistance (finger plethysmography with Modelflow™) and calf pooling and filtration (calf circumference; strain gauge plethysmography) during a series of 10-min head-upright tilts. We first compared (protocol one) low (ICLF; 4 s on, 11 s off) and high (ICHF; 4 s on, 6 s off) frequency 0-100 mm Hg intermittent calf compression with static elastic and inelastic compression stockings and a placebo condition (n = 19, 5 males, aged 23.5 ± 0.1 years). We then compared (protocol two) ICLF applied at 0-40 mm Hg, 0-60 mm Hg, 0-80 mm Hg and 0-100 mm Hg as well as a placebo condition (n = 15, 5 males, aged 22.7 ± 0.5 years). The intervention order was randomized. In protocol one, all compression conditions significantly reduced calf circumference (p < 0.001) compared to placebo after 10-min upright; however, this reduction was greater in ICLF (-0.88 ± 0.18%) and ICHF (-1.14 ± 0.21%) conditions than both elastic (+0.49 ± 0.17%) and inelastic (-0.01 ± 0.19%) compression (p < 0.001). ICLF and ICHF, but not elastic or inelastic compression, were associated with improved stroke volume (p ≤ 0.001), allowing cardiac output to be maintained at a reduced heart rate (p < 0.001) without increases in vascular resistance responses, increasing hemodynamic reserve. ICHF showed no significant benefit over ICLF, evidenced by the lack of significant difference between ICLF and ICHF in any parameter measured. In protocol two, 0-60 mm Hg ICLF was considered the optimal intermittent compression because it was the lowest pressure that abolished the increase in calf circumference during orthostasis, while improving SV (p = 0.002), and reducing HR (p < 0.001) throughout tilt. Intermittent calf compression from 0 to 60 mm Hg ICLF is the optimal intermittent compression paradigm to ameliorate orthostatic fluid shifts and improve hemodynamic control. Commonly prescribed static calf compression garments do not improve orthostatic cardiovascular responses.

Assessment of Post-Operative Bleeding and Venous Thromboembolism after Initial 24-Hour Intermittent Pneumatic Calf Compression Followed by Rivaroxaban versus Enoxaparin in Elective Hip and Knee Arthroplasty: A Multicentre Randomised Controlled Trial

Background: Venous thromboembolism (VTE) is a serious complication following total hip replacement (THR) and total knee replacement (TKR). There are limited studies addressing the impact of mechanical intermittent pneumatic calf compression (IPCC) followed by pharmacological prophylaxis on rate of bleeding and VTE among this cohort of patients. Objectives: Our study assessed 24-hour IPCC followed by oral rivaroxaban 10 mg daily versus subcutaneous enoxaparin 40 mg daily for 14 days post-TKR and 35 days post-THR, with 6-month post-operative follow-up. Design: A multicentre open-label, randomised controlled trial (RCT) with intention to treat analysis. Setting: Primary health care. Multicenter tertiary referral centres, Tasmania and Victoria, Australia. Methods and participants: A two arm RCT recruited 750 patients referred for elective hip and knee arthroplasty to tertiary referral centres in Northern Tasmania and Victoria, Australia. All patients had IPCC (Kendall SCDTM, Covidien, MA, USA) fitted immediately post-operatively for 48-hours. Main outcomes measures: The outcomes included post-operative bleeding and occurrence of either symptomatic or asymptomatic VTE. Secondary outcomes include length of hospital stay, rate of blood transfusion and compliance to the study medications. Results: 51.8% of participants were female, average age was 66.9 (SD 11.1) years, and 54.7% had undergone TKR arthroplasty. In postoperative baseline comparisons, there were no significant differences between the two groups in blood drained (P=0.771), haemoglobin change between days 2 and 4 (P=0.473), blood transfusion rate (P=0.892) or length of hospital stay (P=0.651). At 6 months post-surgery, a total of 21 participants (2.8%) had developed VTE with 8/369 (2.1%) cases in the rivaroxaban group versus 13/371 (3.5%) in the enoxaparin group (P=0.377). Conclusions: Our study showed that at the 6-month post-operative follow-up, 24-hour IPCC followed by chemical prophylaxis was effective in VTE prophylaxis with no increased bleeding risk. These findings support employing immediate postoperative IPCC followed by pharmacological prophylaxis in arthroplasty. Further trials to confirm these findings are warranted. Clinical Trial Number: The study is registered prospectively in the Australian New Zealand Clinical Trials Registry under ACTRN12609000762257 and in the WHO International Clinical Trial Registry Platform: (http://apps.who.int/trialsearch/Trial3.aspx?trialid=ACTRN12609000762257). Funding Statement: This study was supported by the Surgery and Pathology Departments, Launceston General Hospital, Launceston, Tasmania, Australia, in affiliation with the University of Tasmania, Australia. Declaration of Interests: The authors declare no conflict of interests. Ethics Approval Statement: The study was approved by the Tasmanian Human Research Ethics Committee, Australia.

Randomized controlled trial of a new portable calf compression device (Venowave) for prevention of venous thrombosis in high‐risk neurosurgical patients

Patients undergoing neurosurgical procedures are at risk of venous thromboembolism (VTE), but often have contraindications for anticoagulant prophylaxis. To assess the efficacy and tolerability of a new, lightweight, portable, battery-powered, intermittent calf compression device, Venowave, for the prevention of VTE in neurosurgical inpatients. We performed an open randomized controlled trial comparing Venowave with control for the prevention of VTE in patients undergoing neurosurgery. The primary outcome was the composite of asymptomatic deep vein thrombosis (DVT) detected by screening venography or compression ultrasound performed on day 9 (± 2 days) and symptomatic VTE. We randomized 75 patients to receive Venowave devices and 75 to the control group. All patients were prescribed graduated compression stockings and physiotherapy. VTE occurred in three patients randomized to Venowave and in 14 patients randomized to control (4.0% vs. 18.7%, relative risk 0.21; 95% confidence interval 0.05-0.75, P = 0.008). Similar reductions were seen for proximal DVT (2.7% vs. 8.0%) and symptomatic VTE (0% vs. 2.7%), and the results were consistent in all subgroups examined. Venowave devices are effective in preventing VTE in high-risk neurosurgical patients.

Clinical significance of preventive treatment of thrombosis for patients undergoing gynecological surgery with high risk factors

To explore the clinical significance of preventive treatment of thrombosis for patients undergoing gynecological surgeries with high risk factors. Prospectively, randomized and cases controlled study was performed in 143 patients underwent gynecological surgery with high risk factors to explore the prevention effectiveness and safety in morbidity of lower extremity deep venous thrombosis (LDVT) and relative effected factors, who were enrolled to three groups according to different preventive treatment: group using intermittent pneumatic calf compression (IPC) in 47 cases, group using low-molecular-weight hepairin (LMWH) in 48 cases and control group in 48 cases with no prevention strategy. The morbidity of LDVT on lower extremity was 6% (6/94) in group IPC and 1% (1/96) in group LMWH, 18% (17/96) in control group, which was obviously reduced in group IPC and group LMWH than that in control group (P < 0.05), while there was no significantly difference between group IPC and group LMWH (P > 0.05). After surgery in 3 or 4 days, the morbidity of LDVT in group IPC was 1/6, zero in group LMWH and 71% (12/17) in control group, there was significantly reduced in group IPC and group LMWH than that in control group (P < 0.05). There was no side-effects in group IPC, only 1 case in group LMWH presented small quantity bleed in vagina remnant, while no incision bleeding and bleed tendency. Single-variate analysis indicated that elder age, abdominal surgeries and malignant tumor were as the independent factors to effect preventive treatment of thrombosis (P < 0.05). LDVT in patients underwent gynecological surgeries with high risk factors can be obviously reduced and delayed by preventive treatment, which is no side-effects, while be effected by the factors of elder age, abdominal surgeries and malignant tumor.

Prevention of Venous Thromboembolism

Of the various prophylactic agents evaluated, four have been found to be effective. These are oral anticoagulants, low-dose heparin, mechanical devices which increase venous blood-flow in the leg, and Dextran. Oral anticoagulants have been shown to be effective in patients having abdominal, thoracic, or hip surgery, when treatment was started either before surgery or in the immediate postoperative period. They have also been shown to be effective in medical patients. The evidence derives from studies which showed that treatment can reduce total mortality, prevents venous thromboembolism detected clinically or at autopsy, and prevents thrombosis diagnosed with venography. On the other hand, the incidence of thrombosis diagnosed by 125I-fibrinogen scanning was not reduced when oral anticoagulants were started just before or just after surgery. This suggests that oral anticoagulant treatment starting in the immediate postoperative period may not prevent formation of the initial thrombotic nidus, but is clinically effective because it prevents extension of the nidus to form a significant thrombus. Bleeding has been a significant complication in almost all studies of surgical patients, and this is the major factor which has prevented widespread use of oral anticoagulant prophylaxis. In addition, the need for careful laboratory monitoring makes this approach inconvenient and adds to its expense. Low-dose heparin has been shown to be effective in general surgical and medical patients, but results have been inconclusive in patients having elective hip surgery, and this approach is probably ineffective in patients with hip fracture. In general surgical patients, low-dose heparin prophylaxis has been shown to prevent pulmonary embolism diagnosed at autopsy examination or with lung scanning, and calf and thigh vein thrombosis diagnosed with 125I-fibrinogen leg-scanning. A slight, but statistically significant, increase in the frequency of wound hematoma and a greater postoperative hematocrit fall have been reported when heparin was given three times daily, but not with the twice daily heparin injection regimen. In these studies, low-dose heparin was given without laboratory control of its anticoagulant effect, so that this prophylactic approach is simple, but the need for subcutaneous injections is a disadvantage of this approach. Results with methods which increase venous blood-flow in the leg have varied, depending on the technic used. Active measures, such as intermittent pneumatic calf compression or peroperative electrical calf muscle stimulation, have been shown to prevent thrombosis detected with 125I-fibrinogen leg-scanning. However, while the evidence suggests that both methods are effective in relatively low risk patients, they may have limited value in the high risk patient who is confined to bed for a long time. These methods are free of side effects and relatively inexpensive, but intermittent calf compression, in particular, is slightly cumbersome...

Multimodal Thromboprophylaxis for Total Hip and Knee Arthroplasty Based on Risk Assessment

Orthopaedic surgeons are increasingly challenged to find a prophylaxis regimen that protects patients from thromboembolism while minimizing adverse clinical outcomes such as bleeding. We used a multimodal approach in which the treatment regimen is selected according to patient risk factors. We retrospectively reviewed the records on 1179 consecutive total joint arthroplasties in 970 patients who had undergone primary and revision total hip and total knee replacement. Preoperatively, patients were assigned to one of two deep venous thrombosis prophylactic regimens on the basis of an assessment of their risk factors. Eight hundred and fifty-six patients (1046 operations) were considered to be low risk and were managed with aspirin, dipyridamole, or clopidogrel bisulfate as well as intermittent pneumatic calf compression devices. One hundred and fourteen patients (133 operations) were considered to be high risk and were managed with low-molecular-weight heparin or warfarin and intermittent calf compression. All patients were mobilized from bed within twenty-four hours after surgery, and all underwent Doppler ultrasonography within the twenty-four hours before hospital discharge. All of the patients were followed for six months postoperatively. The prevalence of asymptomatic and symptomatic distal and proximal deep venous thrombosis, symptomatic and fatal pulmonary emboli, overall mortality, and bleeding complications was determined. Thrombotic events were expressed as a percentage of 1179 operations because some patients had two or more operations. Overall, there were no fatal pulmonary emboli, three symptomatic pulmonary emboli (prevalence, 0.25%), and five clinically symptomatic deep venous thrombi (0.4%). Sixty-one asymptomatic deep venous thrombi (5.2%) were found with use of routine postoperative Doppler ultrasound scans. There were three deaths (prevalence, 0.25%) that were unrelated to thromboembolism, and there were two nonfatal gastrointestinal bleeding events (prevalence, 0.17%). Wound hematomas occurred in association with five (0.4%) of the 1179 operations. Three nonfatal pulmonary emboli (prevalence, 0.3%) were detected in association with the 1046 procedures in the low-risk group, and none were detected in association with the 133 operations in the high-risk group (p = 0.767). Clinically symptomatic deep venous thrombosis was detected in association with four (0.38%) of the 1046 operations in the low-risk group and one (0.75%) of the 133 operations in the high-risk group (p = 0.93). Asymptomatic distal deep venous thrombosis was detected in association with thirty-seven (3.5%) of the 1046 procedures in the low-risk group and four (3.0%) of the 133 operations in the high-risk group. Asymptomatic proximal thrombosis was detected in association with fourteen (1.3%) of the 1046 procedures in the low-risk group and six (4.5%) of the 133 procedures in the high-risk group (p = 0.03). Wound hematomas occurred only in patients being managed with warfarin or low-modular-weight heparin (p = 0.0001). A multimodal thromboembolic prophylactic regimen is consistent with protecting patients while limiting adverse clinical outcomes secondary to thromboembolic, vascular, and bleeding complications.

Venous Stasis, Deep Venous Thrombosis and Airline Flight: Can the Seat be Fixed?

Deep venous thrombosis (DVT) and pulmonary embolization (PE) associated with air travel are directly related to the duration of flight and seating in non-aisle seats. In this study, we assessed a modification of a standard airline seat (NewSit) designed to decrease the incidence of DVT on long flights. This seat raises the feet from the floor, facilitates mobility, and permits intermittent calf compression. Air plethysmography (APG) was used to measure the ejected venous volume of the calves of 25 volunteers before and after sitting for 5 hours on the conventional and modified seats. The mean percent (+/- standard deviation [SD]) increase in venous volume for the conventional seat after 5 hours of continuous sitting was significantly greater than that for the modified seat (26.6 +/- 18.5% vs 3.5 +/- 13.1%, P < 0.0001 by paired, two-tailed t-test). Improvement (any) was seen in 23 of 25 patients, with 15 of the 23 (65%) being better than 1 SD of the mean (P < 0.0001 by Chi-square analysis). This study suggests that the leg movement and calf compression associated with the modified airline seat (NewSit) may decrease the probability of DVT due to prolonged periods of sitting by reducing venous stasis as measured by APG. Further studies involving a larger randomized patient cohort, as well as analysis of the effect of this modification on specific coagulation markers such as tissue plasminogen activator and fibrin D-dimer, are planned.

Popliteal artery volume flow measurement: A new and reliable predictor of early patency after infrainguinal balloon angioplasty and subintimal dissection

We have investigated whether popliteal artery volume flow (PAVF) measured immediately after balloon angioplasties of the superficial femoral artery-popliteal segments (SFA/POP) was predictive of early (30 days) and mid-term (6 months) arterial thrombosis. During the last 24 months, 203 patients (56% men) with a mean age of 73 +/- 9 years had 268 duplex-guided balloon angioplasties of the SFA/POP. Critical ischemia was the indication in 36%. Group I included 176 (66%) with stenoses, and group II had 92 (34%) with occlusions. All patients had completion duplex examinations that included three measurements of PAVF of below-the-knee popliteal artery. Early (30 days) thrombosis of the treated femoropopliteal arterial segment developed in 10 patients (3.7%), three in group I (1.7%) and seven in group II (7.6%; P < .04). All 10 cases of early thrombosis were in patients with TransAtlantic Inter-Society Consensus (TASC) class C (6/185, 3.2%) and D (4/26, 15%) lesions. Moreover, the 19% incidence (n = 4) of early thrombosis in patients with PAVF <100 mL/min (mean, 73 +/- 24 mL/min; range, 20 to 99 mL/min) was higher compared with the 2.4% rate for patients with higher flows (mean, 176 +/- 60 mL/min; range, 100 to 450 mL/min; P < .01). At 6 months of follow-up, femoropopliteal occlusions had developed in nine more patients, and it became apparent that low PAVF measurements were still predictive of thrombosis (29%) when compared with higher PAVF cases (6%; P < .002). Log-rank comparison of survival curves for cumulative primary stenosis-free patency in group I and group II demonstrated a statistically significant difference (P < .02). PAVF <100 mL/min and TASC classification were significant predictors of early (30 days) and mid-term (6 months) arterial thrombosis after femoropopliteal angioplasties. PAVF was the most powerful predictor of arterial thrombosis. The respective 6-month and 12-month limb salvage rates were 98% and 94% for patients with claudication and 88% and 85% for those with limb-threatening ischemia (P < .0001). Our results demonstrate that low PAVF is the most powerful predictor of early (30 days) and mid-term (6 months) arterial thrombosis after femoropopliteal interventions. In the presence of a low postprocedure PAVF (<100 mL/min), one may consider not reversing the heparin or using intermittent calf compression, or both, to augment the arterial flow.

The influence of inflation rate on the hematologic and hemodynamic effects of intermittent pneumatic calf compression for deep vein thrombosis prophylaxis

The study was conducted to determine whether the different inflation rates of intermittent pneumatic compression systems used in deep vein thrombosis prophylaxis influence their hematologic and hemodynamic effects. A rapidly inflating intermittent calf compression system and a more gently inflating equivalent were applied to 20 healthy male volunteers for 2 hours each. Venous blood samples were taken for analysis of blood coagulation and fibrinolytic potential. Blood flow velocity was measured in the femoral vein with Doppler ultrasound. Tissue factor pathway inhibitor significantly increased after the 2 hours of compression for both pumps (78.0 to 85.0 ng/mL rapid, P = .004; 76.5 to 78.0 ng/mL gentle, P = .5), as did plasminogen activator activity (0.85 to 1.05 IU/mL rapid, P = .006; 0.85 to 1.5 IU/mL gentle, P = 0.5). Plasminogen activator inhibitor 1 activity was reduced, although only approaching significance for the gentle system (16.5 to 14.3 AU/mL, P = .06). A D-dimer test for global fibrinolysis showed significant increases for the gently inflating system (97 to 411 ng/mL P < .001) but not for the rapidly inflating system (276 to 350 ng/mL P = .9). The rapidly inflating system produced significantly higher venous peak velocities and augmentations as expected. Although the data confirm that both types of intermittent compression suppress procoagulant activation, rapid inflation clearly produced no extra benefit in increasing global fibrinolysis, and may be less hematologically effective.

Graduated compression stockings in the prevention of postoperative deep vein thrombosis

This review examines the role of graduated elastic compression stockings in the prevention of postoperative deep vein thrombosis. Used alone compression stockings reduce the incidence of postoperative deep vein thrombosis by approximately 60 per cent and when used in combination with other preventive methods, such as low dose heparin or intermittent calf compression, they further reduce the incidence by up to 85 per cent.

Venous haemodynamics during laparoscopic surgery: A cause for concern

Summary. During laparoscopic surgery, intra-abdominal pressure is increased by the pneumoperitoneum. This may impede venous return from the legs and so predispose to venous thrombosis. The aim of this study was to investigate femoral venous velocity and femoral venous diameter during pneumoperitoneum, and to assess the reversibility of this effect by use of an intermittent calf compression device. Fourteen patients undergoing laparoscopic cholecystectomy were studied. A duplex scanner was used to assess femoral venous velocity (both with and without use of a calf compression device), and diameter, before, during and after establishment of a pneumoperitoneum. There was a significant reduction in the femoral venous velocity (from 0.15-0.105 m/s, P<0.01) and a significant increase in femoral venous diameter (from 6.55-9.3 mm, P<0.01) during pneumoperitoneum. The use of a calf compression device reversed this effect (augmented velocity of 0.395 m/s during pneumoperitoneum, P<0.01). These results indicate that laparoscopic surgery affects venous haemodynamics and this effect can be reversed with calf compression devices.

The Use of Intermittent Pneumatic Calf Compression in Isolated Femoral Vein Reconstruction

Objective: To report two cases of isolated femoral vein injury reconstruction and a review of the literature. Design: Case report. Setting: Hull Royal Infirmary, Kingston Upon Hull. Patients: Two patients presenting with civilian trauma. Interventions: Spiral vein graft interposition and postoperative intermittent pneumatic calf compression. Main outcome measure: Limb salvage, vein patency and limb swelling. Results: Satisfactory limb salvage, femoral vein patency and absent limb swelling in both cases.

Intermittent calf and foot compression increases lower extremity blood flow

Although foot compression increases foot skin perfusion and calf compression increases popliteal artery blood flow, these compression techniques have not been evaluated in combination. The purpose of this study was to evaluate whether calf and foot compression applied separately and simultaneously increase popliteal artery blood flow and/or foot skin perfusion, and to assess the relative merits of compression in patients with superficial femoral artery occlusion. Twenty-two legs from 12 normal volunteers with ankle/brachial indices (ABIs) > 0.96, and 10 legs from 7 claudicator patients with angiographically documented superficial femoral artery (SFA) occlusion and patent popliteal arteries with ABIs < 0.8 were studied in the sitting position. Calf and foot cuffs connected to a rapidly inflating and deflating timed-pressure pump (Art-Assist-AA 1000; ACI Medical Inc., San Marcos, California) were applied to the subject in the sitting position. Skin blood flow of the great toe was measured with a laser doppler (Laserflo model BPM 403A; TSI Inc., St. Paul, Minnesota), and popliteal artery blood flow was measured using duplex ultrasonography (ATL-Ultramark 9; Advanced Tech Laboratory, Bothell, Washington). Foot and calf compression was applied separately and simultaneously at 120 mm Hg pressure, with a 10-second inflation and 20-second deflation cycle. Popliteal artery blood flow and foot skin perfusion were recorded and the mean of 6 cycles calculated. Precompression popliteal artery blood flow (mL/min) for volunteers was 38.86 +/- 3.94, and for patients was 86.30 +/- 14.55 (P = 0.001). Precompression foot skin perfusion (mL/min/ 100/g tissue) for volunteers was 1.67 +/- 0.29, and for patients was 4.00 +/- 0.92 (P = 0.01). With the application of calf, foot, and simultaneous calf and foot compression, the popliteal artery blood flow increased in volunteers by 124%, 54%, and 173%, respectively, and in patients by 76%, 13%, and 50%. Foot skin perfusion increased in volunteers by 260%, 500%, and 328%, respectively, and in patients by 116%, 246%, and 188%. Relative increases in popliteal artery blood flow and foot skin perfusion were higher in volunteers compared with patients during compression; however, the absolute values for foot skin perfusion and popliteal artery blood flow were consistently higher in patients. Measured in the sitting position, the resting popliteal artery blood flow and foot skin perfusion are greater in patients with SFA occlusion compared with normal volunteers. Following compression, popliteal artery blood flow and foot skin perfusion increased in both groups, but relatively more in volunteers. Increases in popliteal artery blood flow are significantly higher with calf compression than with foot compression for both groups. A patent SFA allows for additive increases in popliteal artery blood flow with simultaneous foot and calf compression in normal persons, whereas this is not observed in patients. However, the increases in foot skin perfusion in patients with an occluded SFA parallel the increases shown in normal volunteers, with separate and simultaneous foot and calf compression.

Variations in Pulmonary Artery Blood Temperatures Caused by Intermittent Pneumatic Calf Compression Stockings

Variations in Pulmonary Artery Blood Temperatures Caused by Intermittent Pneumatic Calf Compression Stockings

Prevention of venous thromboembolism in gynecologic surgery patients

To reduce the morbidity and mortality of postoperative deep vein thrombosis and pulmonary embolism, effective prophylactic methods must be used. An assessment of the individual patient's risk is essential in deciding the most appropriate method. In general, women over 40 years of age and all women with other risk factors benefit from some form of prophylaxis. For patients with benign gynecologic conditions, low-dose heparin (every 12 hours) and perioperative intermittent pneumatic calf compression have been shown to be of benefit. Patients at higher risk, such as gynecologic oncology patients, should receive more intense prophylaxis with either low-dose heparin (every 8 hours) or prolonged (5 days) intermittent pneumatic calf compression. Of the two methods, the latter has no significant complications and is therefore our method of choice.

Physician Practices in the Prevention of Venous Thromboembolism

To determine the rate of use of prophylaxis for venous thromboembolism in high-risk hospital patients. A retrospective medical record review. A community-wide study in 16 short-stay hospitals in central Massachusetts. A total of 2017 patients with multiple risk factors for venous thromboembolism. On the basis of age, length of hospitalization, and the presence of at least one additional major risk factor, 17% of 151,349 discharges (25,410 patients) were identified as being at high risk for venous thromboembolism. Eight percent of these discharges were randomly selected for medical record review. Prophylaxis for venous thromboembolism was received by 32% of these high-risk patients. Prophylaxis use among the 16 study hospitals varied widely, ranging from 9% to 56%, and was higher in teaching hospitals than in nonteaching hospitals (44% compared with 19%; P less than 0.001). One or more of the following methods of prophylaxis was used: low-dose heparin (78%), intermittent calf compression (13%), warfarin (12%), and inferior vena caval filter (3%). Use of prophylaxis increased with the number of risk factors identified (P less than 0.001). Prophylaxis for venous thromboemobolism is underused, particularly in nonteaching hospitals.