The Use of Point-of-Care Ultrasound (POCUS) in the Diagnosis of Deep Vein Thrombosis

The incidence and risk factors of proximal lower extremity deep vein thrombosis without pharmacologic prophylaxis in critically ill surgical Taiwanese patients: A prospective study

Background

Venous thromboembolism (VTE) in critically ill patients has been well-studied in Western countries. Many studies have developed risk assessments and established pharmacological protocols to prevent deep venous thrombosis (DVT). However, the DVT rate and need for pharmacologic VTE prophylaxis in critically ill Taiwanese patients are limited. This study aimed to prospectively determine the DVT incidence, risk factors, and outcomes in critically ill Taiwanese patients who do not receive pharmacologic VTE prophylaxis.

Methods

We conducted a prospective study in a surgical intensive care unit (SICU) of a tertiary academic medical center in Taiwan. Adult patients admitted to SICU from March 2021 to June 2022 received proximal lower extremities DVT surveillance with venous duplex ultrasound. No patient received pharmacologic VTE prophylaxis. The outcomes were the incidence and risk factors of DVT.

Results

Among 501 enrolled SICU patients, 21 patients (4.2%) were diagnosed with proximal lower extremities DVT. In a multivariate regression analysis, hypoalbuminemia (odd ratio (OR) = 6.061, 95% confidence interval (CI): 1.067-34.421), femoral central venous catheter (OR = 4.515, 95% CI: 1.547-13.174), ICU stays more than 10 days (OR = 4.017, 95% CI: 1.270-12.707), and swollen leg (OR = 3.427, 95% CI: 1.075-10.930) were independent risk factors for DVT. In addition, patients with proximal lower extremities DVT have more extended ventilator days (p = 0.045) and ICU stays (p = 0.044).

Conclusion

Our findings indicate critically ill Taiwanese patients have a higher incidence of DVT than results from prior retrospective studies in the Asian population. Physicians who care for this population should consider the specific risk factors for DVT and prescribe pharmacologic prophylaxis in high-risk groups.

Ultrasound Performed by Emergency Physicians for Deep Vein Thrombosis: A Systematic Review

Introduction

Point-of-care ultrasound (POCUS) performed by emergency physicians (EP) has emerged as an effective alternative to radiology department ultrasounds for the diagnosis of lower extremity deep vein thrombosis (DVT). Systematic reviews suggested good sensitivity and specificity overall for EP-performed POCUS for DVT diagnosis, yet high levels of heterogeneity were reported.

Methods

In this systematic review and meta-analysis, we aimed to provide the most up-to-date estimates of the accuracy of EP-performed POCUS for diagnosis of DVT and to explore potential correlations with test performance. We performed systematic searches in MEDLINE and Embase for original, primary data articles from January 2012-June 2021 comparing the efficacy of POCUS performed by EPs to the local standard. Quality Assessment of Diagnostic Accuracy Studies-2 for individual articles are reported. We obtained summary measures of sensitivity, specificity, and their corresponding 95% confidence intervals (CI) using bivariate mixed-effects regression models. We performed meta-regression, subgroup, and sensitivity analyses as planned in the protocol CRD42021268799 submitted to PROSPERO.

Results

Fifteen publications fit the inclusion criteria, totaling 2,511 examinations. Pooled sensitivity and specificity were 90% (95% CI 82%-95%) and 95% (CI 91%-97%), respectively. Subgroup analyses by EP experience found significantly better accuracy for exams performed by EP specialists (93%, CI 88%-97%) vs trainees (77%, CI 60%-94%). Specificity for EP specialists (97%, CI 94%-99%) was higher than for trainees (87%, CI 76%-99%, P = 0.01). Three-point compression ultrasound (CUS) was more sensitive than two-point CUS but was only statistically significant when limited to EP specialists (92% vs 88%, P = 0.07, and 95% vs 88%, P = 0.02, respectively).

Conclusion

Point-of-care ultrasound performed by emergency physicians is sensitive and specific for the diagnosis of suspected DVT when performed by trained attending EPs. Three-point compression ultrasound examination may be more sensitive than two-point CUS.

Systematic review of the use of ultrasound for venous assessment and venous thrombosis screening in spaceflight

The validity of venous ultrasound (V-US) for the diagnosis of deep vein thrombosis (DVT) during spaceflight is unknown and difficult to establish in diagnostic accuracy and diagnostic management studies in this context. We performed a systematic review of the use of V-US in the upper-body venous system in spaceflight to identify microgravity-related changes and the effect of venous interventions to reverse them, and to assess appropriateness of spaceflight V-US with terrestrial standards. An appropriateness tool was developed following expert panel discussions and review of terrestrial diagnostic studies, including criteria relevant to crew experience, in-flight equipment, assessment sites, ultrasound modalities, and DVT diagnosis. Microgravity-related findings reported as an increase in internal jugular vein (IJV) cross-sectional area and pressure were associated with reduced, stagnant, and retrograde flow. Changes were on average responsive to venous interventions using lower body negative pressure, Bracelets, Valsalva and Mueller manoeuvres, and contralateral IJV compression. In comparison with terrestrial standards, spaceflight V-US did not meet all appropriateness criteria. In DVT studies (n = 3), a single thrombosis was reported and only ultrasound modality criterion met the standards. In the other studies (n = 15), all the criteria were appropriate except crew experience criterion, which was appropriate in only four studies. Future practice and research should account for microgravity-related changes, evaluate individual effect of venous interventions, and adopt Earth-based V-US standards.

Remote Expert DVT Triaging of Novice-User Compression Sonography with AI-Guidance

BACKGROUND

Compression ultrasonography of the leg is established for triaging proximal lower extremity deep vein thrombosis (DVT). AutoDVT, a machine-learning software, provides a tool for nonspecialists in acquiring compression sequences to be reviewed by an expert for patient triage. The purpose of this study was to test image acquisition and remote triaging in a clinical setting.

METHODS

Patients with a suspected DVT were recruited at 2 centers in Germany and Greece. Enrolled patients underwent an artificial intelligence-guided two-point compression examination by a nonspecialist using a handheld ultrasound device prior to a standard scan. Images collected by the software were uploaded for blind review by 5 qualified physicians. All reviewers rated the quality of all sequences on the American College of Emergency Physicians (ACEP) image quality scale (score 1-5, ≥ 3 defined as adequate imaging quality) and for an ACEP score ≥3, chose "Compressible", "Incompressible", or "Other". Sensitivity and specificity were calculated for adequate quality scans with an assessment as "Compressible" or "Incompressible". We define this group as diagnostic quality. To simulate a triaging clinical algorithm, a post hoc analysis was performed merging the "incomplete", the "low quality", and the "Incompressible" into a high-risk group for proximal DVT.

RESULTS

Seventy-three patients (average age 64.2 years, 44% females) were eligible for inclusion and scanned by 3 nonultrasound-qualified healthcare professionals. Three patients were excluded from further analysis due to incomplete scans. Sixty two of 70 (88.57%) of the completed scans were judged to be of adequate image quality with an average ACEP score of 3.35. Forty seven of 62 adequate AutoDVT scans were assessed as diagnostic quality, of which 8 were interpreted as positive for proximal DVT by the reviewers resulting in a sensitivity of 100% and specificity of 95.12%. When simulating a triaging algorithm, 34/73 (46.58%) of patients would be triaged as high risk and 8 would be confirmed as positive for proximal DVT (6 in the diagnostic and 2 in the low-quality cohort). Of 39/73 patients triaged as low risk, all were negative for proximal DVT in standard duplex; thus, this triaging algorithm could potentially save 53.42% of standard duplex scans.

CONCLUSIONS

Machine learning software was able to aid nonexperts in acquiring valid ultrasound images of venous compressions and allowed remote triaging. This strategy allows faster diagnosis and treatment of high-risk patients and can spare the need for multiple unnecessary duplex scans, the vast majority being negative.

Venous Thromboembolism in Pregnancy: Challenges and Solutions

Venous thromboembolism (VTE) is a serious medical condition that can lead to severe morbidity and mortality, making it a significant public health concern. VTE is a multifactorial condition that results from the interaction of genetic, acquired, and environmental factors. Physiological changes during pregnancy increase the risk of VTE as they express Virchow's triad (increased coagulation factors, decreased fibrinolysis, trauma, and venous stasis). Moreover, pregnancy-related risk factors, such as advanced maternal age, obesity, multiple gestations, and cesarean delivery, further increase the risk of VTE. Managing VTE in pregnancy is challenging due to the complexity of balancing the risks and benefits of anticoagulant therapy for both the mother and the fetus. A multidisciplinary approach involving obstetricians, hematologists, and neonatologists, is necessary to ensure optimal outcomes for both the mother and baby. This review aims to discuss the current challenges associated with VTE in pregnancy and identify potential solutions for improving outcomes for pregnant women at risk for VTE.

Main applications of point-of care ultrasound in palliative care

Combined with a physical examination, clinical ultrasound offers a valuable complement that can help guide clinical decision-making. In various medical and surgical specialties, it is increasingly used for diagnostic and therapeutic purposes. Due to recent technological advances, smaller and more affordable ultrasound machines are now being developed for use in home hospice care. The purpose of this paper is to describe how clinical ultrasound may be applied in Palliative Care, where it can be a valuable tool to assist the clinician in making better clinical decisions and to assist in accurately guiding palliative procedures. Furthermore, it can be used to identify unnecessary hospitalizations and prevent them from occurring. Training programs with specific objectives are necessary to implement clinical ultrasound in Palliative Care, as well as defining learning curves and promoting alliances with scientific societies that recognize the teaching, care and research trajectory for accreditation of competencies.

Comparison of Two-Point Compression Ultrasonography Performed by Emergency Medicine Doctors and Radiologists in Detection of Deep Vein Thrombosis

Venous thromboembolism (VTE) is a serious coagulation disorder that includes deep vein thrombosis (DVT) and pulmonary embolism and is an important cause of hospitalization and death. This study aimed to evaluate the compliance of the emergency doctor and radiologist in diagnosing DVT in the emergency department using the two-point compression ultrasonography (USG) method.

Patients and Methods This prospective cross-sectional study was performed between February and July 2022 in the Emergency Medicine Clinic of a tertiary university hospital with patients who were thought to have DVT and had lower extremity venous USG indication. Demographic information of patients, clinical markers used in the Wells score, and USG results of the emergency doctors and radiologists were recorded in the study form.

Results A total of 400 patients were included in the study. The mean age of the study patients was 59.8 ± 18.0 years, and 54.4% (n = 217) of the patients were male. There was a significant difference in the incidence of DVT between those with a Wells score of 2 or less and those above 2 (n = 67, 21.8% vs. n = 41, 47.1%; p < 0.001). Regarding interobserver agreement in the evaluation of DVT by emergency medicine doctor and radiologist, kappa values were 0.81 (95% confidence interval [CI]: 0.71–0.91) for the right femoral vein, 0.89 (95% CI: 0.81–0.97) for the left femoral vein. It was found to be 0.81 (95% CI: 0.76–0.86) for all lower extremity vein USGs.

Conclusions There is a very good level of agreement between the emergency department and the radiologist in diagnosing DVT with USG.

The Incremental Role of Multiorgan Point-of-Care Ultrasounds in the Emergency Setting

Point-of-care ultrasonography (POCUS) represents a goal-directed ultrasound examination performed by clinicians directly involved in patient healthcare. POCUS has been widely used in emergency departments, where US exams allow physicians to make quick diagnoses and to recognize early life-threatening conditions which require prompt interventions. Although initially meant for the real-time evaluation of cardiovascular and respiratory pathologies, its use has been extended to a wide range of clinical applications, such as screening for deep-vein thrombosis and trauma, abdominal ultrasonography of the right upper quadrant and appendix, and guidance for invasive procedures. Moreover, recently, bedside ultrasounds have been used to evaluate the fluid balance and to guide decongestive therapy in acutely decompensated heart failure. The aim of the present review was to discuss the most common applications of POCUS in the emergency setting.

Measuring the Compression Force Required for Vascular Shortening in Ultrasonic Vascular Models

Background Vascular compression is important for deep vein thrombosis screening. However, pressure analysis of ultrasound vessel models has not been performed. Therefore, we compared the human popliteal vein and several ultrasound vessel models at 50% compression. Methodology Four major ultrasound vascular models used in Japan and the popliteal vein of one subject constituted our measurement targets. Using a pressure-sensitive measuring device, the compressive force required to shorten the vessel diameter by 50% was determined. Results The compression force that shortened the popliteal vein by 50% was measured to be 191 ± 65 g. The blue phantom, ultrasound CV Pad II, ultrasound training block, and UGP-GEL required compression force of 701 ± 8 g, 265 ± 12 g, 697 ± 20 g, and 745 ± 15 g, respectively. The compression force for the ultrasound training block was 2.6 times higher than that for the ultrasound CV Pad II. The gel material around the vessels was the same; however, different vascular tubes required 2.6 times higher compression force. Conclusions This study showed that the objective numerical values of the compressive force were required to compress an ultrasound vascular model. Reproduction of the compressibility of veins required either removing the vascular structure or using thin tubing material.