A systematic review of the accuracy of ultrasound in the diagnosis of deep venous thrombosis in asymptomatic patients

Incidence of Venous Thromboembolism after Primary Total Hip Arthroplasty with Mechanical Prophylaxis in Hong Kong Chinese

Purpose

The incidence of deep vein thrombosis (DVT) following total hip arthroplasty (THA) without chemoprophylaxis could be as high as 50% in Caucasians. However, according to several subsequent studies, the incidence of venous thromboembolic events (VTE) in Asians was much lower. The routine use of chemoprophylaxis, which could potentially cause increased bleeding, infection, and wound complications, has been questioned in low-incidence populations. The objective of this study is to determine the incidence of VTE after primary THA without chemoprophylaxis in an Asian population using a fast-track rehabilitation protocol and to verify the safety profile for use of 'mechanical prophylaxis alone' in patients with standard risk of VTE.

Materials and Methods

This is a retrospective cohort study of 542 Hong Kong Chinese patients who underwent primary THA without chemoprophylaxis. All patients received intermittent pneumatic compression and graduated compression stockings as mechanical prophylaxis. Multimodal pain management was applied in order to facilitate early mobilisation. Routine duplex ultrasonography was performed between the fourth and seventh postoperative day for detection of proximal DVT.

Results

All patients were Chinese (mean age, 63.0±11.9 years). Six patients developed proximal DVT (incidence rate, 1.1%). None of the patients had symptomatic or fatal pulmonary embolism.

Conclusion

The incidence of VTE after primary THA without chemical prophylaxis can be low in Asian populations when following a fast-track rehabilitation protocol. Mechanical prophylaxis alone can be regarded as a reasonably safe practice in terms of a balanced benefit-to-risk ratio for Asian patients with standard risk of VTE.

Deep venous thrombosis post mechanical thrombectomy in acute ischaemic stroke

A woman in her 20s presented with neck pain, slurred speech and left-sided weakness. She successfully underwent mechanical thrombectomy (MT) for total occlusion of the basilar artery and made full neurological recovery. Initial ultrasound Doppler of legs (USDL) did not show any deep vein thrombosis (DVT). However, 2 days later, a repeat USDL revealed an extensive proximal DVT in the right common femoral vein. CT scan confirmed a haematoma arising from the femoral access site causing compression of the adjacent common femoral vein. This may have initiated DVT formation or exacerbated extension of a previously undetected DVT. Echocardiogram revealed a patent foramen ovale. As the patient was asymptomatic, delayed or missed diagnosis of DVT would have put her at risk of life-threatening pulmonary embolism or further strokes. Clinicians should maintain a high index of suspicion of DVT as a direct procedural complication from MT so treatment can be initiated promptly.

A systematic review of routine post operative screening duplex ultrasound after thermal and non-thermal endovenous ablation

OBJECTIVE

The Society of Vascular Surgery and the American Venous Forum recommend duplex ultrasound (DUS) following endovenous ablation. However, this screening may not be cost-effective or clinically indicated. The most common abnormal finding, endovenous heat-induced thrombosis (EHIT level 1-2), represents extension of thrombus from the saphenous <50% across the femoral or popliteal vein, which is thought to have a benign course regardless of intervention. The likelihood of venous thromboembolism (VTE) after thermal and non-thermal ablations was explored to determine the utility of routine postoperative DUS.

METHODS

This is an updated and expanded systematic review including data from randomized trials and large observational studies (≥150 patients) of thermal and non-thermal ablations, examining the incidence of VTE. Using PubMed and EMBASE, 4584 publications were screened from 2000 through 2020. After applying inclusion and exclusion criteria, 72 studies were included. Random effects DerSimonian-Laird method was conducted to obtain the pooled incidence. We calculated the number of tests needed to detect one VTE, and the cost was derived from Center for Medicare Services tables.

RESULTS

A total of 31,663 patients were included. The pooled incidence of EHIT II-IV, deep venous thrombosis (DVT), and pulmonary embolism (PE) was 1.32% (95% confidence interval [CI], 0.75%-2.02%); DVT (excluding EHIT), 0.20% (95% CI, 0.0%-0.2%); EHIT (I-IV), 2.51% (95% CI, 1.54%-3.68%); and EHIT (II-IV), 1.00% (95% CI, 0.51%-1.61%). There was no mortality. There was a lower DVT rate in thermal vs non-thermal ablations (0.23% vs 0.43%; P = .02); however, for all VTE (EHIT I-IV + DVT + PE), thermal techniques had more thrombosis (2.5% vs 0.5%; P <.001). When clinical significance is defined as DVT + EHIT (II-IV), 175 studies are needed to identify one VTE, costing $21,813 per "significant VTE." Patients receiving pharmacological prophylaxis had less EHIT I-IV compared with those who did not (3.04% vs 1.63%; P < .001); those who received DUS during the first post-op week had three times higher EHIT incidence compared with those whose first DUS was >7 days postoperative (6.6% vs 2.4%; P < .001).

CONCLUSIONS

For thermal and non-thermal endovenous ablations, the incidence of VTE diagnosed with routine DUS is small and without clear clinical significance but caries a high cost. The Society of Vascular Surgery and the American Venous Forum recommendation to perform DUS within 72 hours is not justified by these data. We recommend a more targeted post-ablation scanning protocol including symptomatic patients and those at high risk.

Direct oral anticoagulants decrease treatment failure for acute lower extremity deep venous thrombosis

OBJECTIVE

Optimal medical therapy for acute lower extremity deep venous thrombosis (DVT) remains an enigma. While clinical trials demonstrate non-inferiority with an oral anti-Xa inhibitor, or direct oral anticoagulant (DOAC), versus combined low-molecular weight heparin (LMWH) and oral vitamin K antagonist (VKA), the most effective regimen remains to be determined.

METHODS

This study is a single-center retrospective cohort study from October 2014 to December 2015 of patients with a diagnosis of acute DVT and subsequent serial lower extremity venous duplex. Demographics, medical history, medications, serial ultrasound findings, as well as the primary anticoagulant used for treatment were collected and analyzed by two independent data extractors. Treatment failure was defined as any new DVT or progression of an existing DVT within 3 months of diagnosis of the index clot. Risk factors for treatment failure were assessed using standard odds ratios and Fischer's exact test.

RESULTS

Among 496 patients with an acute lower extremity DVT, 54% (n = 266) were men, mean age was 61 years, 35% (n = 174) involved the popliteal or more proximal segments, and 442 had documentation of the primary treatment for DVT: 20% (n = 90) received nothing; 20% (n = 92) received an oral VKA; 34% (n = 149) received a DOAC; 20% (n = 90) received LMWH; and 5% (n = 21) received another class of anticoagulant. Within 3 months, 21% (n=89 out of 427) had treatment failure defined as any new DVT or progression of prior DVT. Patients treated with a DOAC were less likely to experience treatment failure when compared with any other treatment (odds ratio 0.43; 95% confidence intervals [0.23, 0.79]; p = 0.0069) and when compared with traditional oral VKA (OR 0.44; 95% CI [0.21, 0.92]; p = 0.029). None of prior history of DVT, pulmonary embolism, thrombophilia, renal insufficiency, hepatic insufficiency, cancer, or antiplatelet therapy correlated with treatment failure. Treatment outcome did not correlate with being on any anticoagulation versus none (p = 0.74), nor did it correlate with the duration of treatment (<3 months versus ≥3 months) (p = 0.42). Proximal and distal DVTs showed no difference in treatment failure (19% versus 22%, respectively; p = 0.43).

CONCLUSION

In summary, the use of a DOAC for acute lower extremity DVT yielded better overall outcomes and fewer treatment failures at 3 months as compared to traditional oral VKA therapy based on serial duplex imaging.

Deep Vein Thrombosis is Common After Cardiac Ablation and Pre-Procedural D-Dimer Could Predict Risk

PURPOSE

Cardiac catheter ablations are an established treatment for supraventricular tachycardia (SVT) involving prolonged cannulation of the common femoral vein with multiple catheters. This study aimed to identify the risk of deep vein thrombosis (DVT) by studying the frequency of this complication after catheter ablation.

METHODS

This was a prospective multi-centre cohort study of patients undergoing cardiac ablation for atrioventricular nodal re-entry tachycardia or right-sided accessory atrioventricular connection. Those taking anticoagulation or antiplatelet therapy prior to the procedure were excluded. Following the procedure, bilateral venous duplex ultrasonography from the popliteal vein to the inferior vena cava for DVT was undertaken at 24 hours and between 10 to 14 days.

RESULTS

Eighty (80) patients (mean age 47.6 yrs [SD 13.4] with 67% female) underwent cardiac ablation (median duration 70 mins). Seven (7) patients developed acute DVT in either the femoral or external iliac vein of the intervention leg, giving a frequency of 8.8% (95% CI 3.6-17.2%). No thrombus was seen in the contralateral leg (p=0.023). An elevated D-dimer prior to the procedure was significantly more frequent in patients developing DVT (42.9% vs 4.1%, p=0.0081; OR 17.0). No other patient or procedural characteristics significantly influenced the risk of DVT.

CONCLUSION

In patients without peri-procedural anticoagulation catheter ablation precipitated DVT in the catheterised femoral or iliac veins in 8.8% of patients. Peri-procedure prophylactic anticoagulation may be considered for all patients undergoing catheter ablation for SVT.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT03877770.

Incidence and risk factors of preoperative deep venous thrombosis in closed tibial shaft fracture: a prospective cohort study

OBJECTIVE

To investigate the preoperative morbidity of deep venous thrombosis (DVT) and predictive risk factors associated with DVT after closed tibial shaft fracture.

METHODS

Ultrasonography and blood analyses were performed preoperatively in patients who sustained tibial shaft fracture between October 2014 and December 2018. Univariate analyses were used in the data of demographics, comorbidities, mechanism of injury, concomitant fractures and laboratory biomarkers. Multivariate logistic regression analyses were conducted to determine the independent risk factors associated with DVT.

RESULTS

In total, 918 patients with an operatively treated tibial shaft fracture were included, among whom 122 patients had preoperative DVTs, indicating a crude morbidity of 13.3%. Ninety-two of 758 (12.1%) patients with isolated tibial shaft fracture developed DVT, while 30 of 160 (18.8%) patients with concurrent fracture presented with DVT. The average interval between fracture and initial diagnosis of DVT was 3.1 days (median, 2 days), ranging from 0 to 33 days. Among DVT-positive patients, 16 (13.1%) patients presented with proximal DVT and 106 (86.9%) patients had distal DVT. Multivariate logistic regression analysis showed four independent risk factors were significantly correlated to the development of DVT, including increased age (OR = 1.17, p = 0.003), diabetes (OR = 1.99, p = 0.009), serum hydroxybutyrate dehydrogenase > 182 U/L (OR = 1.83, p = 0.008), and delay to DUS (in each day) (OR = 1.13, p < 0.001).

CONCLUSION

In the present cohort study, the incidence of DVT was 12.1% in patients with isolated tibial shaft fracture. We suggest individualized risk stratification and early anticoagulation for patients with high risk factors including pre-existing diabetes, HBDH > 182 U/L, delay to DUS and older age.

LEVEL OF EVIDENCE

Level III, a prospective cohort study.

Prevalence, risk, and outcome of deep vein thrombosis in acute respiratory distress syndrome

BACKGROUND

Few data exist on deep vein thrombosis (DVT) in patients with acute respiratory distress syndrome (ARDS), a group of heterogeneous diseases characterized by acute hypoxemia.

STUDY DESIGN AND METHODS

We retrospectively enrolled 225 adults with ARDS admitted to the Beijing Chao-Yang Hospital and the First Affiliated Hospital of Shandong First Medical University between 1 January 2015 and 30 June 2020. We analyzed clinical, laboratory, and echocardiography data for groups with and without DVT and for direct (pulmonary) and indirect (extrapulmonary) ARDS subgroups.

RESULTS

Ninety (40.0%) patients developed DVT. Compared with the non-DVT group, patients with DVT were older, had lower serum creatinine levels, lower partial pressure of arterial oxygen/fraction of inspired oxygen, higher serum procalcitonin levels, higher Padua prediction scores, and higher proportions of sedation and invasive mechanical ventilation (IMV). Multivariate analysis showed an association between age, serum creatinine level, IMV, and DVT in the ARDS cohort. The sensitivity and specificity of corresponding receiver operating characteristic curves were not inferior to those of the Padua prediction score and the Caprini score for screening for DVT in the three ARDS cohorts. Patients with DVT had a significantly lower survival rate than those without DVT in the overall ARDS cohort and in the groups with direct and indirect ARDS.

CONCLUSIONS

The prevalence of DVT is high in patients with ARDS. The risk factors for DVT are age, serum creatinine level, and IMV. DVT is associated with decreased survival in patients with ARDS.

Tranexamic acid in patients with complex stones undergoing percutaneous nephrolithotomy: a randomised, double-blinded, placebo-controlled trial

OBJECTIVES

To assess the efficacy and safety of single-dose tranexamic acid on the blood transfusion rate and outcomes of patients with complex kidney stones undergoing percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

In a randomised, double-blinded, placebo-controlled trial, 192 patients with complex kidney stone (Guy's Stone Scores III-IV) were prospectively enrolled and randomised (1:1 ratio) to receive either one dose of tranexamic acid (1 g) or a placebo at the time of anaesthetic induction for PCNL. The primary outcome measure was the occurrence rate of perioperative blood transfusion. The secondary outcome measures included blood loss, operative time, stone-free rate (SFR), and complications. ClinicalTrials.gov identifier: NCT02966236.

RESULTS

The overall risk of receiving a blood transfusion was reduced in the tranexamic acid group (2.2% vs 10.4%; relative risk, 0.21, 95% confidence interval [CI] 0.03-0.76, P = 0.033; number-needed-to-treat: 12). Patients randomised to the tranexamic acid group had a higher immediate and 3-month SFR compared with those in the placebo group (29% vs 14.7%, odds ratio [OR] 2.37, 95% CI 1.15-4.87, P = 0.019, and 46.2% vs 28.1%, OR 2.20, 95% CI 1.20-4.02, P = 0.011, respectively). Faster haemoglobin recovery occurred in patients in the tranexamic acid group (mean, 21.3 days; P = 0.001). No statistical differences were found in operative time and complications between groups.

CONCLUSIONS

Tranexamic acid administration is safe and reduces the need for blood transfusion by five-times in patients with complex kidney stones undergoing PCNL. Moreover, tranexamic acid may contribute to better stone clearance rate and faster haemoglobin recovery without increasing complications. A single dose of tranexamic acid at the time of anaesthetic induction could be considered standard clinical practice for patients with complex kidney stones undergoing PCNL.

Serological Parameters and Vascular Investigation for a Better Assessment in DVT during Pregnancy-A Systematic Review

Pregnancy and the postpartum period represent a condition characterized by a thrombotic predisposition. The majority of pregnant women do not face acute or severe thrombotic events. In general, mild inconveniences such as leg swelling or moderately painful thrombotic events (phlebitis) are encountered. However, when pregnancy is associated with inherited or acquired deficits that affect homeostasis, the risk of acute or even life-threatening events can increase significantly. The major consequence is the loss of the fetus or the venous thromboembolism that endangers the mother's life. Venous thromboembolism is caused by deep vein thrombosis, therefore timely detection and especially the assessment of the extent of the thrombotic event are crucial. In this paper we have summarized the most important paraclinical investigations. The study emphasizes the importance of selecting the methods of investigation. The right choice allows establishing a correct diagnosis and individualizing the treatment.

Unusual coexistence of double inferior vena cava with nutcracker syndrome-a case report and review of the literature

Knowledge of vessel anomalies is significant for all specialists in clinical practice and may prevent serious complications following medical interventions. Here, the rare coexistence of a duplicated inferior vena cava (IVC) and nutcracker syndrome in a 42-year-old female patient with atypical abdominal pain is presented, using two complementary radiological techniques (colour Doppler ultrasonography and computed tomography angiography). The right renal vein was found to be compressed when passing between the superior mesenteric artery and the abdominal aorta. The lumen dimensions (width × height) of the right IVC and left IVC at the level of termination were 15.8 × 17.7 mm and 13.4 × 12.4 mm, respectively. Ultrasonography revealed low blood flow in the left IVC that was reversed, and thus blood travelled in the same caudal direction as in the aorta. In the right IVC, however, flow travelled in the cranial direction. The simultaneous existence of a duplicated IVC and nutcracker syndrome is an extremely rare vessel anomaly; nevertheless, this dual presence may result in clinical symptoms and would have an impact on medical operations and even minor medical procedures.

Current Ultrasound Technologies and Instrumentation in the Assessment and Monitoring of COVID-19 Positive Patients

Since the emergence of the COVID-19 pandemic in December of 2019, clinicians and scientists all over the world have faced overwhelming new challenges that not only threaten their own communities and countries but also the world at large. These challenges have been enormous and debilitating, as the infrastructure of many countries, including developing ones, had little or no resources to deal with the crisis. Even in developed countries, such as Italy, health systems have been so inundated by cases that health care facilities became oversaturated and could not accommodate the unexpected influx of patients to be tested. Initially, resources were focused on testing to identify those who were infected. When it became clear that the virus mainly attacks the lungs by causing parenchymal changes in the form of multifocal pneumonia of different levels of severity, imaging became paramount in the assessment of disease severity, progression, and even response to treatment. As a result, there was a need to establish protocols for imaging of the lungs in these patients. In North America, the focus was on chest X-ray and computed tomography (CT) as these are widely available and accessible at most health facilities. However, in Europe and China, this was not the case, and a cost-effective and relatively fast imaging modality was needed to scan a large number of sick patients promptly. Hence, ultrasound (US) found its way into the hands of Chinese and European physicians and has since become an important imaging modality in those locations. US is a highly versatile, portable, and inexpensive imaging modality that has application across a broad spectrum of conditions and, in this way, is ideally suited to assess the lungs of COVID-19 patients in the intensive care unit (ICU). This bedside test can be done with little to no movement of the patients from the unit that keeps them in their isolated rooms, thereby limiting further exposure to other health personnel. This article presents a basic introduction to COVID-19 and the use of the US for lung imaging. It further provides a high-level overview of the existing US technologies that are driving development in current and potential future US imaging systems for lung, with a specific emphasis on portable and 3-D systems.

Incidence of asymptomatic deep vein thrombosis in patients with COVID-19 pneumonia and elevated D-dimer levels

AIM

An increased risk of venous thromboembolism (VTE) in patients with COVID-19 pneumonia admitted to intensive care unit (ICU) has been reported. Whether COVID-19 increases the risk of VTE in non-ICU wards remains unknown. We aimed to evaluate the burden of asymptomatic deep vein thrombosis (DVT) in COVID-19 patients with elevated D-dimer levels.

METHOD

In this prospective study consecutive patients hospitalized in non-intensive care units with diagnosis of COVID-19 pneumonia and D-dimer > 1000 ng/ml were screened for asymptomatic DVT with complete compression doppler ultrasound (CCUS). The study was approved by the Institutional Ethics Committee.

RESULTS

The study comprised 156 patients (65.4% male). All but three patients received standard doses of thromboprophylaxis. Median days of hospitalization until CCUS was 9 (IQR 5-17). CCUS was positive for DVT in 23 patients (14.7%), of whom only one was proximal DVT. Seven patients (4.5%) had bilateral distal DVT. Patients with DVT had higher median D-dimer levels: 4527 (IQR 1925-9144) ng/ml vs 2050 (IQR 1428-3235) ng/ml; p < 0.001. D-dimer levels > 1570 ng/ml were associated with asymptomatic DVT (OR 9.1; CI 95% 1.1-70.1). D-dimer showed an acceptable discriminative capacity (area under the ROC curve 0.72, 95% CI 0.61-0.84).

CONCLUSION

In patients admitted with COVID-19 pneumonia and elevated D-dimer levels, the incidence of asymptomatic DVT is similar to that described in other series. Higher cut-off levels for D-dimer might be necessary for the diagnosis of DVT in COVID-19 patients.

Thrombosis rates using aspirin and a compression device as multimodal prophylaxis for lower limb arthroplasty in a screened population

BACKGROUND

Venous thromboembolism (VTE) (Deep vein thrombosis (DVT), and pulmonary embolism (PE)), is a common complication in patients undergoing total joint arthroplasty (TJA). Recently, aspirin was recommended by the American Academy of Orthopaedic Surgeons (AAOS) as VTE prophylaxis following TJA. This study investigates VTE rates in TJA patients using as thromboprophylaxis.

METHODS

DVT was screened for in 396 consecutive total hip or knee arthroplasty procedures. Patients were treated with early mobilisation, calf compression device and 300 mg aspirin for 5 days and then 100 mg aspirin for 5 weeks. All patients received lower-limb duplex ultrasonography prior to discharge. Patients were clinically evaluated at 6 weeks post-op documenting any VTE.

RESULTS

51 TJA's (12.87%) were complicated by VTE: one proximal, 47 distal DVT and 3 PE. No fatal PE occurred. Only four DVT were symptomatic. Of 159 THA, 2 (1.25%) had VTE: one distal DVT and one PE. Of 237 TKA, 49 (20.67%) had VTE: 1 proximal, 46 distal DVT and 2 PE. Patients with a history of diabetes and those receiving TKA were at higher risk of DVT.

CONCLUSION

Multimodal VTE prophylaxis demonstrated a low rate of proximal DVT, PE and bleeding complications. The rate of asymptomatic DVT was high, but most were distal and unlikely to be clinically significant. Patients with diabetes and those receiving TKA could be at higher risk of asymptomatic DVT, and may benefit from closer clinical assessment. These findings suggest aspirin is safe and efficacious when used in combination with mechanical compressors and early mobilisation. However, our findings require further validation, particularly with larger, prospective comparative studies.

The rate of missed diagnosis of lower-limb DVT by ultrasound amounts to 50% or so in patients without symptoms of DVT: A meta-analysis

BACKGROUND

To assess whether the ultrasound (US) is a reliable approach in detecting lower-limb deep-vein thrombosis (DVT) in patients without symptoms of DVT.

METHODS

The research team performed a systematic search in PubMed, Ovid, Cochrane, and Web of Science without language or date restrictions. Full-text reports on prospective diagnostic studies involve the detection of lower-limb proximal and distal DVT in patients without symptoms of DVT using US and venography. A meta-analysis was performed using Meta-DiSc (version 1.4), providing the pooled sensitivity, specificity, positive (LR+) and negative (LR-) likelihood ratios of the detection accuracy of US. There were 4 different classes of subgroup analysis-the class of patients stratified by location of US exam (proximal, distal, whole leg), the class stratified by technique (color/doppler, compression, both modalities), the class stratified by kind of surgery (orthopedic, otherwise hospitalized) and the class stratified by era of publishing (1980s, 1990s, 2000s). The study quality and the risk of bias were evaluated using QUADAS-2, with heterogeneity was assessed and quantified by the Q score and I statistics, respectively.

RESULTS

The meta-analysis included 26 articles containing 41 individual studies with a total of 3951 patients without symptoms of DVT. Using venography as the gold standard, US for proximal DVT had a pooled sensitivity of 59% (95% confidence interval (CI) = 51%-66%) and a pooled specificity of 98% (95% CI = 97%-98%), US for distal DVT had a poor sensitivity of 43% (95% CI = 38%-48%) and a pooled specificity of 95% (95% CI = 94%-96%), US for whole-leg DVT had a pooled sensitivity of 59% (95% CI = 54%-64%) and a pooled specificity of 95% (95% CI = 94%-96%), US for post-major orthopedic surgery patients had a pooled sensitivity of 52% (95% CI = 49%-55%), and US for other types of patients had a pooled sensitivity of 58% (95% CI = 43%-72%). Pure compression technique for DVT had a poor sensitivity of 43% (95% CI = 39%-48%), pure color/doppler technique for DVT had a pooled sensitivity of 58% (95% CI = 53%-63%), compression and color/doppler technique for DVT had a pooled sensitivity of 61% (95% CI = 48%-74%).

CONCLUSION

US could be a useful tool for diagnosing DVT, but it has a lower positive rate and a higher false negative rate. The rate of missed diagnosis of lower-limb DVT by US amounts to 50% or so in the patients without symptoms of DVT. The negative results do not preclude the possibility of DVT and if appropriate heightened surveillance and continued monitoring or try a more accurate inspection method is warranted. The whole leg evaluation and color/doppler technique should be the preferred approach.

Incidence of Symptomatic Pulmonary Embolus and Deep Vein Thrombosis After Knee Arthroscopy in the Pediatric and Adolescent Population

OBJECTIVE

The incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) after pediatric knee arthroscopy is unknown. The purpose of this study was to determine the incidence of venous thromboembolism (VTE) after knee arthroscopy in the pediatric and adolescent population in a high-volume center.

DESIGN

Retrospective cohort study.

SETTING

Tertiary care children's hospital.

PATIENTS

All patients who underwent arthroscopy of the knee for a sports-related injury by 2 surgeons were reviewed. Chief complaint, past medical/surgical history, medications, procedure performed, intraoperative findings, intraoperative complications, and postoperative recovery were reviewed. The incidences of postoperative VTE within 30 days after the procedure were reviewed.

RESULTS

Seven hundred forty-six (358 male and 388 female patients) knee arthroscopies performed from September 2011 to October 2016 by 2 pediatric orthopedic surgeons specializing in sports-related injuries were included. The average age was 15.2 ± 2.72 years. Five patients were suspected to have either DVT or PE postoperatively (0.67%). The overall incidence of symptomatic confirmed VTE after knee arthroscopic procedures was 0.27% (one DVT after a partial lateral meniscectomy and one PE after fixation of an osteochondral lesion).

CONCLUSIONS

The incidence of VTE after pediatric sports medicine knee arthroscopies is low, 0.27%. Patients who present with calf swelling or pain, chest pain, or shortness of breath after arthroscopic surgery should be examined closely.

LEVEL OF EVIDENCE

Level III.

CT IVC venogram: normalized quantitative criteria for patency and thrombosis

PURPOSE

Establish normal attenuation ratios for vein to artery on CT IVC venogram and determine a vascular attenuation ratio diagnostic of thrombus.

METHODS

This retrospective, HIPAA-compliant study included 56 CT IVC venograms. Images were reviewed for the presence of femoral vein or IVC thrombus. Attenuation ratios for each vein and its corresponding artery were calculated by two observers and averaged in four venous stations (right and left femoral veins, and IVC at the confluence of the iliac veins and at the left renal vein). The reference standard for the absence of thrombus was clinical follow-up and for the presence of thrombus it was thrombectomy or catheter venogram. Receiver operating characteristic (ROC) analysis was performed using ratios from one venous station and threshold for thrombus was determined using the Youden's index.

RESULTS

36 of 56 CTs demonstrated no thrombus. 20 CTs demonstrated thrombus, confirmed in eight patients. For CTs with no thrombus, median ratios among the venous stations ranged from 0.89 (IQR 0.83-0.93) to 0.91 (IQR 0.86-0.94). ROC analysis of ratios from a single representative station (left femoral vein, n = 4 confirmed clots) demonstrated an area under the curve (AUC) of 0.994 (p = 0.001) and a threshold of 0.67 for diagnosing thrombus [sensitivity 100% (95% CI 39.76-100%), specificity 97.5% (86.84-99.94%)].

CONCLUSION

The normal attenuation ratio of vein to artery in the absence of venous thrombus on a 3-min delay CT IVC venogram is approximately 0.91. A ratio less than 0.67 is highly suggestive of thrombus.

Differentiation of Deep Venous Thrombosis Among Children With or Without Osteomyelitis

BACKGROUND

Children with osteomyelitis are at risk for deep venous thrombosis (DVT). This study evaluates the characteristics of DVT among children to differentiate between those with and without osteomyelitis.

METHODS

Children with DVT of any cause were studied between 2008 and 2016. Children with DVT and osteomyelitis were compared with those with DVT without osteomyelitis. Another comparison cohort included children with osteomyelitis but without DVT. Comorbidities, severity of illness (SOI), and clinical course were compared between cohorts.

RESULTS

DVT was identified in 224 children, a prevalence of 2.5 per 10,000 children. Among those with DVT, 28 (12.1%) had osteomyelitis. The DVT rate among 466 children with osteomyelitis was 6.0%. Children with osteomyelitis and DVT had greater SOI (9.1 vs. 2.7), bacteremia rate (82.1% vs. 38.4%), methicillin-resistant Staphylococcus aureus rate (89.3% vs. 21.2%), surgeries per child (2.1 vs. 0.7), and intensive care unit admission rate (67.9% vs. 5.9%) than that of children without DVT (P<0.00001). Of 196 children who had DVT without osteomyelitis, 166 (84.7%) had comorbidities including defined hypercoagulability (27 or 13.8%). Children with DVT due to osteomyelitis were without comorbidities or hypercoagulability (P<0.00001). The rate of pulmonary embolism was similar for children with DVT with or without osteomyelitis (3/28, or 10.7% vs. 18/196, or 9.2%).

CONCLUSIONS

Children with DVT and osteomyelitis differ substantially from other children with DVT by the absence of comorbidities or post-thrombotic syndrome. They also differ from children with osteomyelitis without DVT by higher SOI, methicillin-resistant S. aureus rate, and occurrence of intensive care. Awareness of for the characteristics of DVT among children with osteomyelitis will reduce delay to diagnostic ultrasound and improve anticoagulation management which must be carefully coordinated given the high rate of surgery of these children.

LEVEL OF EVIDENCE

Level II-prognostic, retrospective cohort comparison.

Venous thromboembolism prophylaxis after hip preservation surgery: a review and presentation of institutional experience

Venous thromboembolism (VTE) is a serious complication after major orthopedic procedures. The best options for prevention of the VTE are still debated. The most popular evidence-based guidelines for prevention and treatment of VTE in orthopedic surgery addressed the total hip or knee arthroplasty and hip fractures as the major orthopedic surgeries. Majority of studies have evaluated the different modalities of the VTE prophylaxis in patients undergiong hip or knee arthroplasty. Hip preservation surgeries (HPS) including mini-open femoroacetabular osteoplasty, surgical dislocation of the hip, arthroscopic procedures, and periacetabular osteotomy (PAO) are gained popularity in recent two decades. The majority of these patients are young, healthy and active and may not be considered at high risk for VTE. The frequency of VTE in patients undergoing PAO seems to be low between 0 and 5%. There is a paucity of data regarding rates of VTE in young healthy patients undergoing HPS as well as the optimal prevention methods for VTE. Hence current VTE prevention guidelines do not cover HPS adequately. We aimed to review the available literature regarding VTE events and VTE prophylaxis options after HPS. We discussed the available and potential options for prophylaxis of VTE events in these procedures along with our experience in a large cohort of hip preservation surgery.

Ultrasound for Lower Extremity Deep Venous Thrombosis

Venous ultrasound is the standard imaging test for patients suspected of having acute deep venous thrombosis (DVT). There is variability and disagreement among authoritative groups regarding the necessary components of the test. Some protocols include scanning the entire lower extremity, whereas others recommend scans limited to the thigh and knee supplemented with serial testing. Some protocols use gray-scale ultrasound alone, whereas others include Doppler interrogation. Point-of-care ultrasound is recommended in some settings, and there is heterogeneity of these protocols as well. Heterogeneity of recommendations can lead to errors including incorrect application of guidelines, confusion among requesting physicians, and incorrect follow-up. In October 2016, the Society of Radiologists in Ultrasound convened a multidisciplinary panel of experts to evaluate the current evidence to develop recommendations regarding ultrasound protocols for DVT and the terminology used to communicate results to clinicians. Recommendations were made after open discussion and by unanimous consensus.

The panel recommends a comprehensive duplex ultrasound protocol from thigh to ankle with Doppler at selected sites rather than a limited or complete compression-only examination. This protocol is currently performed in many facilities and is achievable with standard ultrasound equipment and personnel. The use of these recommendations will increase the diagnosis of calf DVT and provide better data to explain the presenting symptoms. The panel recommends a single point-of-care protocol that minimizes underdiagnoses of proximal DVT.

The panel recommends the term chronic postthrombotic change to describe the residual material that persists after the acute presentation of DVT to avoid potential overtreatment of prior thrombus.

Adoption of a single standardized comprehensive duplex ultrasound and a single point-of-care examination will enhance patient safety and clinicians’ confidence.

Duplex ultrasound for evaluation of deep venous blood flow in fractured lower extremities

Purpose

Early identification of deep venous thrombosis (DVT) in trauma patients would result in an early initiation of treatment, thereby decreasing the frequency of complications. The aim of the current study was to evaluate the role of duplex ultrasound (DUS) in the evaluation of deep venous blood flow in fractured lower extremities to rule out DVT prior to orthopedic surgery.

Material and methods

In this prospective study a total of 58 patients (42 males and 16 females; mean age of 51.5 ± 19.5 years) with fractured lower extremities were thoroughly evaluated prior to surgery with respect to medical history, fracture pattern, associated injuries, comorbid conditions, and venous duplex ultrasound (VDUS) findings. Each affected limb was assessed for the presence of DVT using a Sonoline G 60S ultrasound unit. The analysis was performed with the Statistical Package for the Social Sciences (SPSS) version 20.

Results

DVT was found in 36 (62.1%) patients with single closed fractures, 9 (15.5%) patients with single opened fractures, 10 (17.2%) patients with multiple closed fractures, and in 3 (5.2%) patients with multiple opened fractures. Sensitivity and specificity of the findings of compressibility and phasicity for DVT detection in patients with fractured lower extremities were 81.25% and 87.50% and 100% and 100% respectively. In addition, the absence of compressibility and phasicity had positive predictive value of 100% and 100% and negative predictive value of 93.75% and 95.65% respectively.

Conclusions

US of DVs in the brightness mode (B-mode) with compression maneuvers should be the first-line imaging modality for suspected DVT in patients with fractured lower extremities.

Detection of Lower Limb Deep Vein Thrombosis: Comparison between Radionuclide Venography and Venous Ultrasonography

Deep vein thrombosis (DVT) is a serious medical condition that needs prompt diagnosis and treatment. The invasive gold standard contrast venography has largely been replaced by venous ultrasonography which is currently the imaging modality of choice for DVT diagnosis. Radionuclide venography (RNV) is an alternative test for DVT, but a few studies have directly compared RNV with venous ultrasonography. This study aims to determine the agreement between RNV and venous ultrasonography for diagnosis of DVT and to determine the predictive value of different RNV findings for the prediction of DVT as detected by venous ultrasonography. Imaging results from patients who underwent both RNV and venous ultrasonography for suspected DVT no more than 1 week apart were reviewed. Results from both modalities were compared to determine inter-modality agreement. A total of 121 venous segments from 102 lower limbs of 75 patients could be compared. The prevalence of DVT as detected by venous ultrasonography was 39%. RNV and venous ultrasonography had moderate agreement (73.6% agreement, κ =0.48, P < 0.0001). The absence of radiotracer activity from a deep venous segment had a positive predictive value (PPV) of 100% for DVT. Other findings such as isolated great saphenous vein activity had a lower PPV. The negative predictive value of RNV is 97.5% with only one patient out of forty with normal RNV found to have DVT by venous ultrasonography, which suggests that DVT can virtually be excluded in patients with normal RNV.

Doppler ultrasound and D-dimer

The diagnosis of venous thromboembolism has evolved considerably with the development of standardized diagnostic algorithms that include clinical probability assessment, D-dimer measurement and the use of non-invasive imaging modalities such as compression ultrasonography and computed tomography angiography. The implementation of these strategies aims to improve resource allocation and patient outcome. The judicious use of these diagnostic tools requires a thorough knowledge of the appropriate clinical setting in which every test and strategy is efficient and can be used safely. For this purpose, D-dimer measurement and compression ultrasonography are complementary: the former is mainly used to exclude VTE in selected patients, while the latter is used to confirm the presence of an underlying DVT.

This review provides an appraisal of the features and use of D-dimer and compression ultrasonography in the context of suspected venous thromboembolism.

Usefulness of clinical predictors for preoperative screening of deep vein thrombosis in hip fractures

BACKGROUND

Recent studies showed that preoperative deep vein thrombosis (DVT) was common after hip fracture (HF), and preoperative DVT screening has been recommended for preventing the fatal DVT-related complications, especially in elderly HF patients with high surgical risk. However, to our knowledge, no previous studies have demonstrated the correlation between the clinical risk predictors and preoperative DVT. Therefore, this study aimed to correlate those clinical predictors related to DVT risk assessment with the incidence of preoperative DVT.

METHODS

A prospective study was conducted, between July 2015 and June 2016, in 92 HF patients. All patients were evaluated for the DVT-related risk, as patients' characteristics, clinical signs, D-dimer, DVT risk assessment score (Wells score and Caprini score), and then underwent doppler ultrasonography preoperatively. The incidence of preoperative DVT was correlated with each clinical risk predictor, and then significant factors were calculated for diagnostic accuracy.

RESULTS

The average patients' age was 78 ± 10 years. Sixty-eight patients (74%) were female. The incidence of preoperative DVT was 16.3% (n = 15). The median time from injury to doppler ultrasonography was 2 days (range 0-150 days). DVT group showed a significantly higher in Wells score and Caprini score compared to the non-DVT group (p < 0.05 all). Sensitivity and specificity of Wells score ≥ 2 and Caprini score ≥12 were 47 and 81, and 93 and 35%, respectively.

CONCLUSION

DVT risk assessment may be helpful for stratifying the risk of preoperative DVT in elderly HFs. Those with Caprini score ≥ 12 should be screened with doppler ultrasonography preoperatively. Those with Wells score 0-1 had low risk for preoperative DVT, so the surgery could perform without delay.

Advanced imaging in acute and chronic deep vein thrombosis

Deep venous thrombosis (DVT) affecting the extremities is a common clinical problem. Prompt imaging aids in rapid diagnosis and adequate treatment. While ultrasound (US) remains the workhorse of detection of extremity venous thrombosis, CT and MRI are commonly used as the problem-solving tools either to visualize the thrombosis in central veins like superior or inferior vena cava (IVC) or to test for the presence of complications like pulmonary embolism (PE). The cross-sectional modalities also offer improved visualization of venous collaterals. The purpose of this article is to review the established modalities used for characterization and diagnosis of DVT, and further explore promising innovations and recent advances in this field.

The incidence of proximal deep vein thrombosis after elective hip arthroscopy: a prospective cohort study in low risk patients

Prospectively assess the incidence of deep venous thrombosis (DVT) using Doppler Ultrasound, in patients receiving elective hip arthroscopy without pharmacologic/mechanical prophylaxis. One hundred and fifteen consecutive patients (mean 35.4 years, SD = 10.3) underwent elective hip arthroscopy. Patients with previous major risk factors for DVT were excluded. Signs/symptoms of DVT/pulmonary embolism were assessed at 2-week post-operatively. A bilateral whole leg Duplex color (Doppler) Ultrasonography was scheduled between 10- and 22-day post-op. The primary outcome was frequency of DVT. Secondary outcomes assessed surgical risk factors. One hundred and ten patients (mean = 34.3 years, SD = 10.1) did not get a DVT. Five patients (mean = 43.8 years, SD = 12.1) were diagnosed with a DVT, 2- to 22-day post-operatively. All DVT patients received arthroscopy in the supine position (n = 76), versus no patients in the lateral position (n = 39). Average traction time was 38 (SD = 4) and 61 (SD = 4) minutes for patients with and without a DVT, respectively. All other a priori defined risk factors were similar. Four out of five patients presented with symptoms of a DVT, confirmed by ultrasound. One patient was without symptoms/clinical findings. Four patients had a DVT restricted to the calf veins; one patient had involvement of the popliteal vein. No patients had proximal extension into the thigh or pelvis. No pulmonary emboli were suspected or occurred. The incidence of deep venous thromboembolism is 4.3%. The majority of patients had symptomatic and distal venous thromboembolic events. This study provides supportive evidence that routine prophylaxis and/or screening may not be necessary in low risk patients undergoing elective hip arthroscopy.

Diagnostic accuracy of point-of-care ultrasound for catheter-related thrombosis in children

BACKGROUND

Compared with consultative US performed by the radiology department, point-of-care US performed by non-radiology physicians can accurately diagnose deep venous thrombosis in adults.

OBJECTIVE

In preparation for a multicenter randomized controlled trial, we determined the accuracy of point-of-care US in diagnosing central venous catheter-related thrombosis in critically ill children.

MATERIALS AND METHODS

Children <18 years old with a central venous catheter who were admitted to the intensive care unit were enrolled. Consultative and point-of-care compression ultrasounds with Doppler were done on the vein where the catheter was inserted within 24 h after insertion. Repeat US was obtained within 24 h of removal of the catheter. All images were centrally, blindly and independently adjudicated for thrombosis by a team of pediatric radiologists. Chance-corrected agreement between readings was calculated.

RESULTS

From 84 children, 152 pairs of consultative and point-of-care ultrasounds were analyzed. A total of 38 (25.0%) consultative and 17 (11.2%) point-of-care ultrasounds were positive for thrombosis. The chance-corrected agreement between consultative and point-of-care ultrasounds was 0.17 (standard error: 0.07; P = 0.008). With consultative US as a reference, the sensitivity of point-of-care US was 28.1% (95% confidence interval: 13.7%-46.7%) with a specificity of 91.8% (95% confidence interval: 84.4%-96.4%). A catheter in the subclavian vein was associated with discordant readings (adjusted odds ratio: 4.00; 95% confidence interval: 1.45-13.94).

CONCLUSION

Point-of-care US, when performed by non-radiology physicians and centrally adjudicated by pediatric radiologists in the setting of a multicenter randomized controlled trial, may not accurately diagnose catheter-related thrombosis in critically ill children.

Coherent flow power Doppler (CFPD): flow detection using spatial coherence beamforming

Power Doppler imaging is a widely used method of flow detection for tissue perfusion monitoring, inflammatory hyperemia detection, deep vein thrombosis diagnosis, and other clinical applications. However, thermal noise and clutter limit its sensitivity and ability to detect slow flow. In addition, large ensembles are required to obtain sufficient sensitivity, which limits frame rate and yields flash artifacts during moderate tissue motion. We propose an alternative method of flow detection using the spatial coherence of backscattered ultrasound echoes. The method enhances slow flow detection and frame rate, while maintaining or improving the signal quality of conventional power Doppler techniques. The feasibility of this method is demonstrated with simulations, flow-phantom experiments, and an in vivo human thyroid study. In comparison with conventional power Doppler imaging, the proposed method can produce Doppler images with 15- to 30-dB SNR improvement. Therefore, the method is able to detect flow with velocities approximately 50% lower than conventional power Doppler, or improve the frame rate by a factor of 3 with comparable image quality. The results show promise for clinical applications of the method.

Venous thromboembolism after total joint arthroplasty: results from a Japanese multicenter cohort study

Introduction

Real-world evidence of the effectiveness of pharmacological thromboprophylaxis for venous thromboembolism (VTE) is limited. Our objective was to assess the effectiveness and safety of thromboprophylactic regimens in Japanese patients undergoing joint replacement in a real-world setting.

Method

Overall, 1,294 patients (1,073 females and 221 males) who underwent total knee arthroplasty (TKA) and 868 patients (740 females and 128 males) who underwent total hip arthroplasty (THA) in 34 Japanese national hospital organization (NHO) hospitals were enrolled. The primary efficacy outcome was the incidence of deep vein thrombosis (DVT) detected by mandatory bilateral ultrasonography up to post-operative day (POD) 10 and pulmonary embolism (PE) up to POD28. The main safety outcomes were bleeding (major or minor) and death from any cause up to POD28.

Results

Patients undergoing TKA (n = 1,294) received fondaparinux (n = 360), enoxaparin (n = 223), unfractionated heparin (n = 72), anti-platelet agents (n = 45), or no medication (n = 594). Patients undergoing THA (n = 868) received fondaparinux (n = 261), enoxaparin (n = 148), unfractionated heparin (n = 32), anti-platelet agents (n = 44), or no medication (n = 383). The incidence rates of sonographically diagnosed DVTs up to POD10 were 24.3% in patients undergoing TKA and 12.6% in patients undergoing THA, and the incidence rates of major bleeding up to POD28 were 1.2% and 2.3%, respectively. Neither fatal bleeding nor fatal pulmonary embolism occurred. Significant risk factors for postoperative VTE identified by multivariate analysis included gender (female) in both TKA and THA groups and use of a foot pump in the TKA group. Only prophylaxis with fondaparinux reduced the occurrence of VTE significantly in both groups. Propensity score matching analysis (fondaparinux versus enoxaparin) showed that the incidence of DVT was lower (relative risk 0.70, 95% confidence interval (CI) 0.58 to 0.85, P = 0.002 in TKA and relative risk 0.73, 95% CI 0.53 to 0.99, P = 0.134 in THA) but that the incidence of major bleeding was higher in the fondaparinux than in the enoxaparin group (3.4% versus 0.5%, P = 0.062 in TKA and 4.9% versus 0%, P = 0.022 in THA).

Conclusions

These findings indicate that prophylaxis with fondaparinux, not enoxaparin, reduces the risk of DVT but increases bleeding tendency in patients undergoing TKA and THA.

Trial registration

University Hospital Medical Information Network Clinical Trials Registry: UMIN000001366. Registered 11 September 2008.

Comparison of fondaparinux with low molecular weight heparin for venous thromboembolism prevention in patients requiring rigid or semi-rigid immobilization for isolated non-surgical below-knee injury

BACKGROUND

In several small studies, anticoagulant therapy reduced the incidence of venous thromboembolism (VTE) in patients with isolated lower-limb injuries.

OBJECTIVES

To compare the efficacy and safety of fondaparinux 2.5 mg (1.5 mg in patients with a creatinine clearance between 30 and 50 mL min(-1) ) over nadroparin 2850 anti-factor Xa IU.

PATIENTS AND METHODS

In this international, multicenter, randomized, open-label study, patients with an isolated non-surgical unilateral below-knee injury having at least one additional major risk factor for VTE and requiring, in the Investigator's opinion, rigid or semi-rigid immobilization for 21-45 days with thromboprophylaxis up to complete mobilization received subcutaneously once-daily either fondaparinux or nadroparin. The primary efficacy outcome was the composite of VTE (symptomatic or ultrasonographically detected asymptomatic deep vein thrombosis of the lower limb or symptomatic pulmonary embolism) and death up to complete mobilization. The main safety outcome was major bleeding.

RESULTS

We randomized 1349 patients (mean age 46 years): 88.7% had a bone fracture, and 83.8% had a plaster cast fitted (mean duration of immobilization, 34 days). The primary efficacy outcome occurred in 15 of 584 patients (2.6%) in the fondaparinux group and 48 of 586 patients (8.2%) in the nadroparin group (odds ratio, 0.30; 95% confidence interval [CI], 0.15-0.54; P < 0.001). A single major bleed was experienced by fondaparinux-treated patients and none by nadroparin-treated patients. These results were maintained up to the end of follow-up.

CONCLUSIONS

Fondaparinux 2.5 mg day(-1) may be a valuable therapeutic option over nadroparin 2850 anti-FXa IU day(-1) for preventing VTE after below-knee injury requiring prolonged immobilization in patients with additional risk factors.

The role of noninvasive and invasive diagnostic imaging techniques for detection of extra-cranial venous system anomalies and developmental variants

The extra-cranial venous system is complex and not well studied in comparison to the peripheral venous system. A newly proposed vascular condition, named chronic cerebrospinal venous insufficiency (CCSVI), described initially in patients with multiple sclerosis (MS) has triggered intense interest in better understanding of the role of extra-cranial venous anomalies and developmental variants. So far, there is no established diagnostic imaging modality, non-invasive or invasive, that can serve as the "gold standard" for detection of these venous anomalies. However, consensus guidelines and standardized imaging protocols are emerging. Most likely, a multimodal imaging approach will ultimately be the most comprehensive means for screening, diagnostic and monitoring purposes. Further research is needed to determine the spectrum of extra-cranial venous pathology and to compare the imaging findings with pathological examinations. The ability to define and reliably detect noninvasively these anomalies is an essential step toward establishing their incidence and prevalence. The role for these anomalies in causing significant hemodynamic consequences for the intra-cranial venous drainage in MS patients and other neurologic disorders, and in aging, remains unproven.

Pulmonary embolism without deep venous thrombosis

BACKGROUND

To identify patients with pulmonary embolism (PE) without deep venous thrombosis (DVT), and to compare them with those with an identifiable source on upper (UED) and lower-extremity venous duplex scans (LED).

METHODS

We performed a retrospective review of 2700 computed tomography angiograms of the chest between January 2008 and September 2010 and identified 230 patients with PE. We then evaluated the results of UED and LED and divided the patients into four groups based on the results of their duplex studies. We compared patients with PE and DVT with those with PE and no DVT in terms of age, gender, size and location of PE, critical illness, malignancy, and in-hospital mortality.

RESULTS

We identified 152 women and 78 men (mean age, 68 years) with PE. One hundred thirty-one patients had a documented source of PE (group 1). Fifty-three patients had negative LED results, but did not undergo UED (group 2). Thirty-one patients did not undergo either LED or UED (group 3). Seven men and eight women had no documented source of PE on UED and LED (group 4). Ten of 15 patients in group 4 had a documented malignancy listed as one of their diagnoses. Because patients in groups 2 and 3 did not undergo complete duplex studies, we excluded them from our analysis. We then reviewed the discharge summaries of patients in groups 1 and 4. There was no statistically significant difference in age and gender distribution, size and location of PE, critical illness, smoking status, cardiovascular disease, trauma, and in-hospital mortality between patients in group 1 and 4. Patients in group 4 had a statistically significant increased prevalence of malignancy (67% vs. 40%, P = 0.046). Patients in group 4 also had a higher percentage of active cancer than those in group 1 (47% vs. 24%, P = 0.084), although not statistically significant. We defined active cancer as either a metastatic disease or a malignancy diagnosed shortly before or after the diagnosis of PE. Patients who were undergoing treatment for cancer at the time of diagnosis of PE were also considered to have active cancer.

CONCLUSION

We demonstrated a statistically significant increased prevalence of malignancy in patients with PE without DVT. However, pathophysiology and clinical significance are the aspects that remain to be understood after accrual of more patients and further research. Possibilities such as de novo thrombosis of pulmonary arteries, complete dislodgement of thrombi from peripheral veins, or false-negative venous duplex need to be explored.

Sequential duplex ultrasound screening for proximal deep venous thrombosis in asymptomatic patients with acetabular and pelvic fractures treated operatively

BACKGROUND

Recent evidence-based practice guidelines recommend against routine ultrasound screening for proximal deep vein thrombosis (DVT) in asymptomatic pelvic fracture patients. However, the majority of trauma surgeons favor this practice. Furthermore, the timing of screening has been inconsistently described. The purpose of this study was to examine the utility of sequential scans in asymptomatic acetabular and pelvic fracture patients treated operatively.

METHODS

In 2003, a screening protocol for DVT was begun for asymptomatic patients with these fractures treated operatively. Duplex ultrasound screening was used to evaluate the lower extremities for proximal DVT. Scans were to be obtained preoperatively and then postoperatively on the day before planned discharge from the hospital. A DVT prophylaxis protocol was also instituted. Between 2003 and 2007, 343 patients were identified for study. Patients were followed for thromboembolic complications for a minimum of 3 months.

RESULTS

Two hundred twenty-nine patients received both preoperative and postoperative scans. Of these, 35 patients (15%) had an asymptomatic DVT: 16 (7%) preoperatively and 19 (8%) postoperatively. Two patients (1%) with negative scans had a postoperative symptomatic pulmonary embolism (PE) diagnosed the day after surgery, but fatal PE did not occur. In the remaining 114 patients, 27 received a prophylactic inferior vena cava filter, 6 had a preoperative symptomatic DVT or PE before scanning, 25 received only the postoperative scan (3 being positive), and 56 were not scanned postoperatively. Of the 56 not scanned postoperatively, 2 (4%) were readmitted with a symptomatic proximal DVT but none for PE, and a fatal PE did not occur.

CONCLUSIONS

Despite the possible diagnostic utility of sequential duplex ultrasound screening, it does not decrease the risk of PE in acetabular and pelvic fracture patients.

LEVEL OF EVIDENCE

IV.

Diagnostic approach to deep venous thrombosis and pulmonary embolism in the critical care setting

Considerable progress has been made during the last 30 years in the prevention, diagnosis, and therapy of venous thromboembolism. This article discusses the epidemiology, pathophysiology, and clinical presentation of the disease as well as the diagnostic uncertainty that exists in the critical care setting. Diagnostic approaches for deep venous thrombosis and pulmonary embolism are considered, including clinical prediction rules, D-dimer, contrast venography, duplex ultrasonography, computed tomographic angiography and venography, magnetic resonance imaging, ventilation–perfusion scanning, chest radiograph, arterial blood gases, electrocardiography, and echocardiography.

[Incidence and distribution of venous thrombosis of the lower limbs diagnosed by duplex ultrasonography after total hip or total knee arthroplasty, and hip fracture surgery. Results from 5981 exams and 2123 cases of venous thrombosis over 10 years]

AIM

To determine the incidence and distribution of lower limb venous thrombosis diagnosed by duplex ultrasonography, including calf exploration, after total hip or knee replacement or hip fracture, and to compare them with the venographic results reported by recent randomized control trials testing new antithrombotic drugs.

PATIENTS AND METHODS

From January 2001 to December 2009, 30,510 standardized report forms incremented a database from which files corresponding to major orthopaedic surgery were selected: 1652 after total hip replacement (THR), 1440 after total knee replacement (TKR) and 2889 after hip fracture (HF). Base-line characteristics, incidence and anatomic distribution of venous thrombosis were analysed in the three populations.

RESULTS

Systematic screening was applied for 95.1% of the exams (n=5689). Incidence of total and proximal venous thrombosis was, respectively, 27.8% (n=460) and 2.8% (n=46) for THR, 32.5% (n=939) and 4.4% (n=126) for HF, and 50.3% (n=724) and 3.8% (n=55) for TKR. Venous thrombosis was distal in 89.3% (n=1896). More than half (n=1014) of distal venous thromboses were strictly muscular soleal locations. Ilio-caval thrombosis incidence was 0.18% (n=11), and superficial venous thrombosis incidence was 1.5% (n=89).

CONCLUSION

This study shows that incidence and distribution of venous thromboses diagnosed with a complete and standardized duplex ultrasonographic screening are very close to the rates published with venographic screening in recent trials.

Central adjudication of venous ultrasound in VTE screening trials: reasons for failure

BACKGROUND

The accuracy of screening ultrasound for venous thrombosis in asymptomatic patients is still a matter of debate. The VENUS study evaluated the accuracy of centrally adjudicated venous ultrasound against venography in patients after major orthopedic surgery and found the sensitivity of ultrasound to be poor for both proximal and distal deep vein thrombus (DVT).

OBJECTIVES

To evaluate whether thrombus characteristics such as location or size influence the diagnostic performance of centrally adjudicated venous ultrasound.

METHODS

All false negative sonograms of the VENUS study were re-evaluated against the corresponding venograms. Discrepancies were categorized into types of diagnostic failures. Within these categories, thrombus characteristics such as location, length or size of thrombus were evaluated.

RESULTS

One hundred and twelve pairs of discrepant ultrasound and venography documents were compared with 28 pairs with concordant results. Discrepancies were caused by local documentation failure (37.5%), failure of the ultrasound method (43.7%) and failure of the central adjudication process (18.7%). The overall size of thrombi was small, which caused about 40% of all sonographic failures with a detection threshold of five Marder points, a thrombus length of 9.5 cm and a number of 3.5 pathological compression manoeuvres. Proximal or distal location of DVT did not affect thrombus detection.

CONCLUSION

If centrally adjudicated ultrasound is to be used in future VTE screening trials, training of local sonographers and central adjudicators needs to be intensified, because asymptomatic DVTs seem to be small and ultrasound sensitivity depends on the number of pathological compression manoeuvres documented in the ultrasound document. In contrast, distal or proximal thrombus location itself does not influence sensitivity.

The utility of screening for deep venous thrombosis in asymptomatic, non-ambulatory neurosurgical patients

OBJECTIVES

Decisions regarding deep venous thrombosis (DVT) prophylaxis are complicated in neurosurgical patients because of the potential for catastrophic bleeding complications. Screening with venous duplex ultrasound (VDUS) may improve outcomes, but can strain hospital resources. Since there is little data to guide VDUS surveillance, we investigated the utility of a comprehensive VDUS screening program in neurosurgical patients.

METHODS

Medical records of patients admitted to the neurosurgical service at a university-affiliated hospital from October 2007 through January 2010 who underwent weekly VDUS of the lower extremities until ambulatory or discharged were retrospectively reviewed. Demographics, comorbidities, interventions, and use of DVT prophylaxis were recorded. All patients in this study were asymptomatic for clinical evidence of DVT. When DVT was identified, VDUS reported its location and progression.

RESULTS

One hundred seventy-four consecutive patients were screened according to the established protocol. They had 312 VDUS studies, 68 (21.8%) of which were positive in 40 (23%) unique patients; 10 were bilateral and two catheter-related. There were no documented pulmonary emboli in this series. Seventeen patients (37.7%) had isolated calf DVT, four of which were bilateral (totaling 21 thrombi), and 9 (20%) had coexistent thrombi in calf and proximal veins. Of the 21 isolated calf DVTs, 15 had follow-up studies and two progressed to the popliteal or ileofemoral vein on follow-up (13.3%). Mechanical prophylaxis was uniformly utilized, but chemical prophylaxis varied based on surgeons' assessment of bleeding risk. DVT developed in 19.3% (28/145) of patients receiving prophylactic medication (unfractionated heparin or low-molecular weight heparin) and 41.4% (12/29) receiving no chemoprophylaxis (P < .001). The only patient characteristic that correlated with DVT risk was a body mass index <30 (9.1% vs 29.4%, P = .01).

CONCLUSIONS

Despite the uniform application of mechanical DVT prophylaxis and the use of chemoprophylaxis in a majority of patients, we found a 23% incidence of DVT in these hospitalized, nonambulatory, neurosurgical patients. No patients with isolated calf DVT had an embolic complication but 13.3% progressed proximally in short-term follow-up. While chemical prophylaxis significantly reduced DVT risk, no factor was sufficiently predictive to exclude patients from screening. These data substantiate the importance of full leg VDUS screening and maximizing DVT prophylaxis in this high risk population.

Accuracy of ultrasonography performed by critical care physicians for the diagnosis of DVT

BACKGROUND

DVT is common among critically ill patients. A rapid and accurate diagnosis is essential for patient care. We assessed the accuracy and timeliness of intensivist-performed compression ultrasonography studies (IP-CUS) for proximal lower extremity DVT (PLEDVT) by comparing results with the formal vascular study (FVS) performed by ultrasonography technicians and interpreted by radiologists.

METHODS

We conducted a multicenter, retrospective review of IP-CUS examinations performed in an ICU by pulmonary and critical care fellows and attending physicians. Patients suspected of having DVT underwent IP-CUS, using a standard two-dimensional compression ultrasonography protocol for the diagnosis of PLEDVT. The IP-CUS data were collected prospectively as part of a quality-improvement initiative. The IP-CUS interpretation was recorded and timed at the end of the examination on a standardized report form. An FVS was then ordered, and the FVS result was used as the criterion standard for calculating sensitivity and specificity. Time delays between the IP-CUS and FVS were recorded.

RESULTS

A total of 128 IP-CUS were compared with an FVS. Eighty-one percent of the IP-CUS were performed by fellows with <2 years of clinical ultrasonography experience. Prevalence of DVT was 20%. IP-CUS studies yielded a sensitivity of 86% and a specificity of 96% with a diagnostic accuracy of 95%. Median time delay between the ordering of FVS and the FVS result was 13.8 h.

CONCLUSIONS

Rapid and accurate diagnosis of proximal lower extremity DVT can be achieved by intensivists performing compression ultrasonography at the bedside.

A mechanobiological investigation of platelets

Understanding mechanotransduction pathways leading to thrombosis will require progressive steps, including determination of the mechanical behavior of the platelet membrane in response to applied loads. The platelet membrane deformation capacity, as quantified by membrane progression into a borosilicate glass micropipette of defined internal diameter, was probed in murine platelets using a controlled range of negative pressure (0-7 cm H(2)O). Based on our observations that the platelet portion outside the micropipette was mostly spherical and that the platelet volume did not change upon aspiration, a novel continuum mechanics-based model of the platelet micropipette aspiration experiment was created, and a new hyperelastic isotropic material model including membrane residual tension was proposed for the platelet membrane. Murine platelet membranes maintained an average linear deformation behavior: L (p)/R (p) = 146,100p (i) × R (p) + 19.923, where L (p) is the platelet length aspirated in the micropipette (m), R (p) is micropipette radius (m) and p (i) is the aspiration pressure (Pa). The theoretical model was used to generate material constants for the murine platelet membrane that allowed for an accurate simulation of the micropipette aspiration experiments. From published results, another set of material constants was established for the human platelet membrane. Limited cases of platelet lysis upon aspiration were analyzed using the theoretical model to determine preliminary membrane tension strength values.

High incidence of deep venous thrombosis after Achilles tendon rupture: a prospective study

Deep venous thrombosis (DVT) is common after lower limb injury, but the effect of prophylactic treatment has not been documented in large randomised trials or meta-analyses. As a result, evidence-based recommendations have not been established. The purpose of this study was to evaluate the incidence of venous thromboembolism in patients with Achilles tendon rupture. A total of 100 consecutive patients with an acute Achilles tendon rupture were included in a prospective study and randomised to either surgical or non-surgical treatment. At 8 weeks after the initiation of treatment, 95/100 patients were screened for DVT using colour duplex sonography (CDS) with blinded interpretation by two experienced examiners and adjudication in cases of disagreement by a third person. A total of 95 patients (79 male and 16 female) with a median (range) age of 41 (24-63) years were screened for CDS at 8 weeks. Of the 95 patients, 32 had a CDS-verified thrombosis, 5 proximal and 27 distal, whereas 3 had non-fatal pulmonary embolism. Surgical treatment was performed in 49 patients, non-surgical in 46. There were no significant differences in DVT frequency between the two treatment groups. The incidence of asymptomatic and symptomatic deep venous thrombosis is high after Achilles tendon rupture and there is a need to define the possible benefit of thromboprophylaxis.

Deep vein thrombosis after reconstructive shoulder arthroplasty: a prospective observational study

This clinical study was performed to document the prevalence of deep vein thrombosis (DVT) after prosthetic shoulder replacement surgery. We prospectively followed 100 consecutive shoulder arthroplasty procedures (total shoulder replacement in 73 and hemiarthroplasty in 27) in 44 male and 56 female patients for 12 weeks (mean age, 67 years; range, 17-88 years). Risk factors for venous thromboembolic disease were assessed preoperatively and postoperatively. A 4-limb surveillance color flow Doppler ultrasound was performed at 2 days (100 patients) and 12 weeks (50 patients randomly selected) after surgery, and the presence and location of DVT were recorded. Postoperative symptomatic or fatal pulmonary emboli (PE) were also recorded. The overall prevalence of DVT was 13.0%, consisting of 13 DVTs in 12 patients. These included 6 ipsilateral and no contralateral upper extremity DVTs and 5 ipsilateral and 2 contralateral lower extremity DVTs. The prevalence of DVT was 10.0% (10/100) at day 2 after surgery and 6.0% (3/50) at week 12 after surgery. The incidence of symptomatic nonfatal PE was 2.0% (2/100), and that of fatal PE was 1.0% (1/100). Risk factors associated with venous thromboembolic disease did not reach statistical significance because of the small study population sample size. At our institution, the prevalence of DVT after reconstructive shoulder arthroplasty was 13.0%, a rate comparable to that after hip arthroplasty (10.3%) but lower than that after knee arthroplasty (27.2%). Shoulder arthroplasty surgeons should be aware of the potential risk of perioperative thromboembolic complications in both the acute and subacute postoperative periods.

The effect of extended post-discharge chemical thromboprophylaxis on venous thromboembolism rates after bariatric surgery: a prospective comparison trial

BACKGROUND

The effect of extended post-discharge thromboprophylaxis (ETP) on venous thromboembolism (VTE) rates following bariatric surgery (BS) is unknown.

METHODS

308 consecutive patients who underwent BS between 2003 and 2007 and who had > 1 month of follow-up were included. In-hospital-only VTE prophylaxis (group A), or extended 10-day ETP (group B) was used in 132 and 176 patients, respectively. All patients underwent bilateral lower extremity venous Doppler studies (BLEVDS) prior to discharge. Primary endpoint was the incidence of VTE within 30 days postoperatively. VTE was defined as a clinically evident deep vein thrombosis or pulmonary embolism documented by positive BLEVDS, or computed chest tomography. The primary safety endpoint was bleeding associated with > or = 2 g/dL decrease in hemoglobin compared with baseline, transfusion or reoperation.

RESULTS

The incidence of VTE was 1.9% (6/308); 66.6% (4/6) of cases occurred after cessation of thromboprophylaxis. There were no deaths in either group. With the exception of percentage open surgical approach (A: 3% versus B: 0%, p = 0.03), percentage conversions (A: 0 versus B: 3.8%, p = 0.01), and hospital stay (A: 3 versus B: 2.2 days, p < 0.0001), the two groups were comparable in relation to age, sex, body mass index, percentage revision surgery, operative time, and history of VTE. VTE rate was significantly higher in group A (A: 4.5% versus B: 0%, p = 0.006). Although morbidity was higher in group A (A: 12.1% versus B: 1.1%, p < 0.0001), no VTE event occurred in patients who had other complications. The incidence of significant bleeding was lower in group B (A: 5.3% versus B: 0.56%, p = 0.02).

CONCLUSIONS

ETP is safe and effective in reducing the incidence of VTE as compared with in-hospital thromboprophylaxis only.

Thromboembolism in pregnancy

Venous thromboembolism in pregnancy is a clinical emergency that has been associated with significant risk for maternal and fetal morbidity and mortality. The adaptation of the maternal hemostatic system to pregnancy predisposes women to an increased risk of thromboembolism. A timely diagnosis of deep venous thrombosis is crucial because up to 24% of patients with untreated deep venous thrombosis develop a pulmonary embolism. Recent clinical guidelines identify compression venous ultrasound as the best way to diagnose deep venous thrombosis in pregnancy and CT pulmonary angiography as the best way to diagnose pulmonary embolism in pregnancy. Therapy involves supportive care and anticoagulation with unfractionated or low molecular weight heparin, depending on the clinical scenario.