The authors have no acknowledgments.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the Duke University Health System institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The protocol was performed using inputs from the following publications3,10. Images were performed on the authors themselves for normal images and as part of routine educational ultrasound scans done for teaching purposes for positive images, with preceding verbal consent as per institutional standards. The patients were selected based on the following criteria: inclusion criteria: any patient with lower extremity pain, swelling, or other clinical reason to suspect DVT; exclusion criteria: patients with a lower extremity amputation who may be missing the popliteal or distal femoral views.
1. Transducer selection
<ol>
	<li>Select the high-frequency linear transducer (5-13 MHz) for the DVT scan to ensure a high-resolution image of the veins. 
	&#8203;NOTE: In obese patients or, occasionally, for the popliteal vein, DVT scanning with a low-frequency curvilinear (2-5 MHz) transducer is necessary to have adequate penetration and depth. However, patients challenging enough to require a low-frequency transducer generally fall outside the scope of point-of-care ultrasound training and usually warrant a comprehensive radiology ultrasound.</li>
</ol>
2. Machine settings
<ol>
	<li>Setting the depth, gain, and focus
	<ol>
		<li>Set the depth so that the target vessels appear in the middle 1/3 of the ultrasound screen by pressing the up or down depth button (between 3-6 cm).</li>
		<li>Set the gain so that the vessels contain a few spots of grey but are otherwise black by pressing the right or left gain buttons (MIS between 0.6-0.8, TIS 0.1).</li>
		<li>If the machine has the capability, aim the focus beam at or slightly below the level of the target vessels by clicking the box on the screen and moving it while holding down the button, and then release.</li>
	</ol>
	</li>
	<li>Set the machine mode. Click on B-Mode, which is a 2-dimensional (2D) greyscale ultrasound exam. Use B-mode to obtain both the non-compressed and compressed images. 
	NOTE: If the B-mode images are ambiguous, providers trained in color and spectral Doppler can consider adding these techniques, but they are not classically included in lower extremity POCUS DVT protocols.</li>
	<li>For optimal scanning ergonomics, place the machine with the ultrasound screen in direct line of sight with the ultrasound probe.</li>
</ol>
3. Patient position
<ol>
	<li>Before scanning, expose the patient&#39;s entire leg from the groin to the knee.</li>
	<li>Place the patient in the supine position as this is the ideal view for DVT examination of the common femoral and femoral veins. Place the patient in the frog-leg position (external rotation at the hip with knees slightly bent) to enable better visualization and scanning of the distal veins. 
	&#8203;NOTE: The popliteal veins can also be assessed with either a frog-leg position or with slight flexion of the knee. Although lateral decubitus and prone positioning might improve visualization (particularly for patients with a higher body mass index), they may not be feasible in all situations (e.g., in critically ill patients or intra-operatively).</li>
</ol>
4. B-mode scanning
<ol>
	<li>Groin and thigh: Apply gel to the patient&#39;s skin in a linear path that traces out the expected path of the ultrasound transducer to increase the efficiency of motion for performing the examination of this part.</li>
	<li>Knee: Apply gel to the transducer itself, as a generous application of gel will facilitate the scanning efficiency.</li>
	<li>Transducer orientation: Place the transducer in a transverse position with the orientation marker directed toward the patient&#39;s right side to ensure that images captured during scanning correspond to the anatomical direction of the structures.</li>
	<li>Place the probe perpendicular to the path of the vein to visualize the vein in a short-axis view. Center the venous structure on the screen. Add long-axis imaging in ambiguous cases by rotating the probe 90&#176; so that the marker points toward the patient&#39;s head.</li>
</ol>
5. Scanning and compression technique
<ol>
	<li>Compression sequence: Begin scanning immediately caudal to the inguinal crease, progress distally sequentially with downward compression, and then release at each point as shown in Figure 13,10.
	<ol>
		<li>Compress such that the entire vein collapses, with the anterior wall touching the posterior wall, while the artery remains pulsatile. Do not apply resting surface pressure between each compression as it can obscure the visualization of the veins. The vein should collapse fully when enough pressure is applied with the transducer to indent an adjacent artery.</li>
	</ol>
	</li>
	<li>Click Save Clip and compress and then release at the common femoral vein (CFV) and femoral artery (FA) just below the inguinal ligament.</li>
	<li>Slide the probe distally about 1 cm and record the same compression and release technique at the CFV and FA at the intake of the great saphenous vein (GSV).</li>
	<li>Click Save Clip, then compress, and release the probe at the CFV at the bifurcation of the FA into the superficial femoral artery (SFA) and deep femoral artery (DFA). Between the SFA and DFA, there will typically be a lateral perforator vein draining from lateral-to-medial into the CFV. Ensure that both the lateral perforator vein and GSV are compressible. 
	NOTE: Though these are superficial veins, clots in these locations have the potential to embolize, resulting in the same life-threatening complications as caused by DVTs.</li>
	<li>Click Save Clip, then compress, and release the probe at the CFV at the bifurcation of the CFV into the femoral vein (FV) and deep femoral vein (DFV).</li>
	<li>Click Save Clip, then compress, and release the probe at the CFV at the popliteal vein behind the knee.</li>
	<li>Once points 1-5 (as in Figure 1) are all fully compressible, scan the FV along the thigh from proximal to distal until the vein disappears in the adductor canal. During this scanning process, attempt to compress the vein approximately every 1-2 cm.</li>
</ol>

<ol>
	<li>Beckman, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Venous+thromboembolism:+A+public+health+concern.">Venous thromboembolism: A public health concern.</a> American Journal of Preventive Medicine. 38, 495-501 (2010).</li><li>Kearon, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+history+of+venous+thromboembolism.">Natural history of venous thromboembolism.</a> Circulation. 107 (23), 22-30 (2003).</li><li>Schafer, J. M., Stickles, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sonoguide:+Ultrasound+guide+for+emergency+physicians.">Sonoguide: Ultrasound guide for emergency physicians.</a> American College of Emergency Physicians. , (2020).</li><li>Pomero, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accuracy+of+emergency+physician-performed+ultrasonography+in+the+diagnosis+of+deep-vein+thrombosis:+A+systematic+review+and+meta-analysis.">Accuracy of emergency physician-performed ultrasonography in the diagnosis of deep-vein thrombosis: A systematic review and meta-analysis.</a> Thrombosis and Haemostasis. 109 (1), 137-145 (2013).</li><li>Theodoro, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+B-mode+ultrasound+in+the+ED+saves+time+in+the+diagnosis+of+deep+vein+thrombosis+(DVT).">Real-time B-mode ultrasound in the ED saves time in the diagnosis of deep vein thrombosis (DVT).</a> American Journal of Emergency Medicine. 22 (3), 197-200 (2004).</li><li>Burnside, P. R., Brown, M. D., Kline, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+review+of+emergency+physician-performed+ultrasonography+for+lower-extremity+deep+vein+thrombosis.">Systematic review of emergency physician-performed ultrasonography for lower-extremity deep vein thrombosis.</a> Academic Emergency Medicine. 15 (6), 493-498 (2008).</li><li>Adhikari, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolated+deep+venous+thrombosis:+Implications+for+2-point+compression+ultrasonography+of+the+lower+extremity.">Isolated deep venous thrombosis: Implications for 2-point compression ultrasonography of the lower extremity.</a> Annals of Emergency Medicine. 66 (3), 262-266 (2015).</li><li>Cogo, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+of+thrombosis+in+patients+with+symptomatic+deep+vein+thrombosis.+Implications+for+simplifying+the+diagnostic+process+with+compression+ultrasound.">Distribution of thrombosis in patients with symptomatic deep vein thrombosis. Implications for simplifying the diagnostic process with compression ultrasound.</a> Archives of Internal Medicine. 153 (24), 2777-2780 (1993).</li><li>Badgett, D. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Duplex+venous+imaging:+Role+for+a+comprehensive+lower+extremity+examination.">Duplex venous imaging: Role for a comprehensive lower extremity examination.</a> Annals of Vascular Surgery. 14 (1), 73-76 (2000).</li><li>Kory, P. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accuracy+of+ultrasonography+performed+by+critical+care+physicians+for+the+diagnosis+of+DVT.">Accuracy of ultrasonography performed by critical care physicians for the diagnosis of DVT.</a> Chest. 139 (3), 538-542 (2011).</li><li>Bates, S. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+of+DVT:+Antithrombotic+therapy+and+prevention+of+thrombosis,+9th+ed:+American+College+of+Chest+Physicians+Evidence-Based+Clinical+Practice+Guidelines.">Diagnosis of DVT: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.</a> Chest. 141 (2), 3512 (2012).</li><li>Wolf, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=American+College+of+Emergency+Physicians+Clinical+Policies+Subcommittee+(Writing+Committee)+on+Thromboembolic+Disease.+Clinical+policy:+Critical+issues+in+the+evaluation+and+management+of+adult+patients+presenting+to+the+emergency+department+with+suspected+acute+venous+thromboembolic+disease.">American College of Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Thromboembolic Disease. Clinical policy: Critical issues in the evaluation and management of adult patients presenting to the emergency department with suspected acute venous thromboembolic disease.</a> Annals of Emergency Medicine. 71 (5), 59-109 (2018).</li><li>Elliott, C. G., Goldhaber, S. Z., Jensen, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delays+in+diagnosis+of+deep+vein+thrombosis+and+pulmonary+embolism.">Delays in diagnosis of deep vein thrombosis and pulmonary embolism.</a> Chest. 128 (5), 3372-3376 (2005).</li><li>Musil, D., Kovacik, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Delay+between+clinical+presentation+and+treatment+of+deep+venous+thrombosis+in+the+lower+limbs+and+regression+of+thrombosis.">Delay between clinical presentation and treatment of deep venous thrombosis in the lower limbs and regression of thrombosis.</a> Phlebology. 37 (2), 120-124 (2022).</li><li>Laursen, C. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focused+sonography+of+the+heart,+lungs,+and+deep+veins+identifies+missed+life-threatening+conditions+in+admitted+patients+with+acute+respiratory+symptoms.">Focused sonography of the heart, lungs, and deep veins identifies missed life-threatening conditions in admitted patients with acute respiratory symptoms.</a> Chest. 144 (6), 1868-1875 (2013).</li><li>Barosse-Antle, M. E., Patel, K. H., Kramer, J. A., Baston, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Point-of-care+ultrasound+for+bedside+diagnosis+of+lower+extremity+DVT.">Point-of-care ultrasound for bedside diagnosis of lower extremity DVT.</a> Chest. 160 (5), 1853-1863 (2021).</li><li>Frankel, H. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidelines+for+the+appropriate+use+of+bedside+general+and+cardiac+ultrasonography+in+the+evaluation+of+critically+ill+patients-Part+I:+General+ultrasonography.">Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients-Part I: General ultrasonography.</a> Critical Care Medicine. 43 (11), 2479-2502 (2015).</li><li>Bernardi, E., Camporese, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+of+deep-vein+thrombosis.">Diagnosis of deep-vein thrombosis.</a> Thrombosis Research. 163, 201-206 (2018).</li><li>Caronia, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resident+performed+two-point+compression+ultrasound+is+inadequate+for+diagnosis+of+deep+vein+thrombosis+in+the+critically+ill.">Resident performed two-point compression ultrasound is inadequate for diagnosis of deep vein thrombosis in the critically ill.</a> Journal of Thrombosis and Thrombolysis. 37 (3), 298-302 (2014).</li></ol>

Robert Jones is an educational material writer for&#160;www.emsono.com. All the other authors have nothing to disclose.

Venous thromboembolism is a common disease, affecting approximately 300,000-600,000 people in the United States annually, with serious complications including pulmonary embolism. Mortality rates in these patients range from 10%-30%2,3,4. Studies have consistently found significant delays in the diagnosis of DVT, with one prospective study of 1,152 patients across 70 medical centers identifying a delay of greater than 1 week in 2...

Deep venous thrombosis (DVT) is the formation of a thrombus in the deep peripheral veins of the extremities. It is a common and important finding, affecting about 300,000-600,000 people in the United States annually1. The propagation of DVT into a pulmonary embolism can occur in 10%-50% of patients and can be deadly, with a mortality rate of 10%-30%, which is higher than the in-hospital mortality for myocardial infarction1,2,3. The risk factors for thrombus formation include hypercoagulable states from genetic factors (family history of DVT, factor V Leiden, protein C or S deficiency), acquired factors (older age, malignancy, obesity, antiphospholipid antibodies, and others), and situational factors (pregnancy, oral contraceptives, recent surgery, travel, trauma, or prolonged immobilization, including from hospitalizations)1.
Early diagnosis of DVT in critically ill patients can expedite patient care and potentially prevent life-threatening complications such as pulmonary embolism, pulmonary infarct, and cardiac involvement1,2,3. A systematic review by Pomero et al. showed a pooled prevalence of 23.1% for DVT in critically ill patients4. Screening for lower extremity DVT has traditionally been performed by radiology ultrasound technicians conducting comprehensive whole-leg duplex exams including both grayscale compression ultrasound and color/spectral Doppler. However, several smaller or community clinical sites lack the direct availability of a sonographer during certain times of the day, such as on nights or weekends, thus creating a delay in patient care5. More recently, acute care providers have devised methods of screening for proximal lower extremity DVTs using point-of-care ultrasound (POCUS)-focused imaging protocols, which demonstrate similarly high sensitivity and specificity in critically ill patients3,4,6. Proximal lower extremity DVTs are defined as DVTs occurring anywhere in the groin, thigh, or knee within the femoral or popliteal venous system. Falling outside of this category are DVTs in the following locations: calf veins (where DVTs are of uncertain clinical significance) and pelvic veins (i.e., the common, external, and internal iliac veins), which are only detectable indirectly using the color and spectral Doppler portion of consultative lower extremity venous ultrasound exams2,3.
Understanding the typical anatomic distribution of DVTs makes performing these bedside exams rapid and easy. First, 70%-99% of proximal lower extremity DVTs involve the femoral or popliteal regions7,8,9. Second, grayscale compression ultrasound is a simple and accurate method for evaluating DVTs; when enough pressure is applied to indent an adjacent artery, normal veins should collapse fully, whereas veins harboring a DVT will not. Combining these principles, the two-zone or three-zone lower extremity DVT POCUS examinations center on compression ultrasound of veins in the inguinal, thigh, and popliteal areas. These techniques have been clinically validated in prior intensive care and emergency medicine studies, demonstrating high sensitivity (96.1%, with a 95% confidence interval (CI) of 90.6%-98.5%) and specificity (96.8%, with a 95% CI of 94.6%-98.1%), with high overall diagnostic accuracy (95%)3,4,6. However, in the experience of the authors, the DVT POCUS exam remains grossly underutilized in the care of critically ill patients, possibly because clinicians are not familiar with the image acquisition sequence. This narrative review with associated visual aids describes an image acquisition protocol for performing a POCUS exam to screen for proximal lower extremity DVTs to assist providers in proper expedited image acquisition during clinical care.

<table><tbody><tr><td>Edge 1 ultrasound machine</td><td>SonoSite</td><td>n/a</td><td>Used to obtain normal images/clips</td></tr><tr><td>SPARQ ultrasound machine</td><td>Philips</td><td>n/a</td><td>Used to obtain abnormal images/clips</td></tr></tbody></table>

point-of-care ultrasound screening for proximal lower extremity deep venous thrombosis

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening sequelae. While whole leg compression ultrasound with color and spectral Doppler is commonly performed in radiology and vascular labs, point-of-care ultrasound (POCUS) is becoming more common in the acute care setting. Providers appropriately trained in focused POCUS can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. This paper describes a simplified yet validated approach to POCUS by describing a three-zone protocol for lower extremity DVT POCUS image acquisition. The protocol explains the steps in obtaining vascular images at six compression points in the lower extremity. Beginning at the level of the proximal thigh and moving distally to the popliteal space, the protocol guides the user through each of the compression points in a stepwise manner: from the common femoral vein to the femoral and deep femoral vein bifurcation, and, finally, to the popliteal vein. Further, a visual aid is provided that may assist providers during real-time image acquisition. The goal in presenting this protocol is to help make proximal lower extremity DVT exams more accessible and efficient for POCUS users at the patient&#39;s bedside.

We describe the interpretation of proximal lower extremity DVT POCUS in patients with an initial suspected DVT.
The attached Figure 2 demonstrates negative POCUS ultrasound images for DVT in the left and right lower extremities, with multi-point compression from the proximal to distal veins as demonstrated in Figure 1 (from thigh to knee). In a negative DVT study, the veins are completely collapsible, with the anterior wall touching t...

Watch this Scientific Journal Video about Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis at JoVE.com

Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis

Traditionally, lower extremity deep venous thrombosis (DVT) is diagnosed by radiology-performed venous duplex ultrasound. Providers appropriately trained in focused point-of-care ultrasound (POCUS) can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. We describe the scanning technique for focused POCUS DVT lower extremity examination.

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening ...

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Medicine

12.8K Views.  Duke University School of Medicine. Ons protocol beschrijft een vereenvoudigde maar gevalideerde benadering van diagnostische point-of-care echografie door een drie-zone protocol te beschrijven voor DVT-beeldacquisitie van de onderste extremiteit. Zorgverleners die op de juiste manier zijn opgeleid in gerichte point-of-care echografie kunnen een snel DVT-onderzoek aan het bed uitvoeren met een hoge gevoeligheid en specificiteit bij ernstig zieke patiënten. Diagnostische POCUS-onderzoeken kunnen de diagnose van DVT versnellen e...

Video: Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis

The Supraclavicular Fossa Ultrasound View for Central Venous Catheter Placement and Catheter Change Over Guidewire

The supraclavicular fossa ultrasound view can be useful for central venous catheter (CVC) placement. Venipuncture of the internal jugular veins (IJV) or subclavian veins is performed with a micro-convex ultrasound probe, using a neonatal abdominal preset with a probe frequency of 10 Mhz at a depth of 10-12 cm. Following insertion of the guidewire into the vein, the probe is shifted to the right supraclavicular fossa to obtain a view of the superior vena cava (SVC), right pulmonary artery and ascending aorta. Under real-time ultrasound view, the guidewire and its J-tip is visualized and pushed forward to the lower SVC. Insertion depth is read from guidewire marks using central venous catheter. CVC is then inserted following skin and venous dilation. The supraclavicular fossa view is most suitable for right IJV CVC insertion. If other insertion sites are chosen the right supraclavicular fossa should be within the sterile field. Scanning of the IJVs, brachiocephalic veins and SVC can reveal significant thrombosis before venipuncture. Misplaced CVCs can be corrected with a change over guidewire technique under real-time ultrasound guidance. In conjunction with a diagnostic lung ultrasound scan, this technique has a potential to replace chest radiograph for confirmation of CVC tip position and exclusion of pneumothorax. Moreover, this view is of advantage in patients with a non-p-wave cardiac rhythm were an intra-cardiac electrocardiography (ECG) is not feasible for CVC tip position confirmation. Limitations of the method are lack of availability of a micro-convex probe and the need for training.

The overall goal is to enable clinicians to insert a central venous catheter under real-time ultrasound guidance via the right supraclavicular fossa view of the lower part of the superior vena cava. This view is useful for different catheter insertion sites, thrombosis detection before insertion and ultrasound guided correction of misplaced catheters.

The supraclavicular fossa ultrasound view can be useful for central venous catheter (CVC) placement. Venipuncture of the internal jugular veins (IJV) or ...

A Multicenter MRI Protocol for the Evaluation and Quantification of Deep Vein Thrombosis

We evaluated a magnetic resonance venography (MRV) approach with gadofosveset to quantify total thrombus volume changes as the principal criterion for treatment efficacy&#160;in a multicenter randomized study comparing edoxaban monotherapy with a heparin/warfarin regimen for acute, symptomatic lower extremities deep vein thrombosis (DVT) treatment. We also used a direct thrombus imaging approach (DTHI, without the use of a contrast agent) to quantify fresh thrombus. We then sought to evaluate the reproducibility of the analysis methodology and applicability of using 3D magnetic resonance venography and direct thrombus imaging for the quantification of DVT in a multicenter trial setting. From 10 randomly selected subjects participating in the edoxaban Thrombus Reduction Imaging Study (eTRIS), total thrombus volume in the entire lower extremity deep venous system was quantified bilaterally. Subjects were imaged using 3D-T1W gradient echo sequences before (direct thrombus imaging, DTHI) and 5 min after injection of 0.03 mmol/kg of gadofosveset trisodium (magnetic resonance venography, MRV). The margins of the DVT on corresponding axial, curved multi-planar reformatted images were manually delineated by two observers to obtain volumetric measurements of the venous thrombi. MRV was used to compute total DVT volume, whereas DTHI was used to compute volume of fresh thrombus. Intra-class correlation (ICC) and Bland Altman analysis were performed to compare inter and intra-observer variability of the analysis. The ICC for inter and intra-observer variability was excellent (0.99 and 0.98, p &#60;0.001, respectively) with no bias on Bland-Altman analysis for MRV images. For DTHI images, the results were slightly lower (ICC = 0.88 and 0.95 respectively, p &#60;0.001), with bias for inter-observer results on Bland-Altman plots. This study showed feasibility of thrombus volume estimation in DVT using MRV with gadofosveset trisodium, with good intra- and inter-observer reproducibility in a multicenter setting.

The goal of this study is to use magnetic resonance venography with long-circulating gadolinium-based contrast agent and direct thrombus imaging for quantitative evaluation of DVT volume in a multicenter, clinical trial setting. Inter- and intra-observer variability assessments were conducted, and reproducibility of the protocol was determined.

We evaluated a magnetic resonance venography (MRV) approach with gadofosveset to quantify total thrombus volume changes as the principal criterion for ...

Deep Vein Thrombosis Induced by Stasis in Mice Monitored by High Frequency Ultrasonography

Venous thrombosis is a common condition affecting 1 - 2% of the population, with an annual incidence of 1 in 500. Venous thrombosis can lead to death through pulmonary embolism or results in the post-thrombotic syndrome, characterized by chronic leg pain, swelling, and ulceration, or in chronic pulmonary hypertension resulting in significant chronic respiratory compromise. This is the most common cardiovascular disease after myocardial infarction and ischemic stroke and is a clinical challenge for all medical disciplines, as it can complicate the course of other disorders such as cancer, systemic disease, surgery, and major trauma.
Experimental models are necessary to study these mechanisms. The stasis model induces consistent thrombus size and a quantifiable amount of thrombus. However, it is necessary to systematically ligate side branches of the inferior vena cava to avoid variability in thrombus sizes and any erroneous data interpretation. We have developed a non-invasive technique to measure thrombus size using ultrasonography. Using this technique, we can assess thrombus development and resolution over time in the same animal. This approach limits the number of mice required for quantification of venous thrombosis consistent with the principle of replacement, reduction, and refinement of animals in research. We have demonstrated that thrombus weight and histological analysis of thrombus size correlate with measurement obtained with ultrasonography. Therefore, the current study describes how to induce deep vein thrombosis in mice using the inferior vena cava stasis model and how to monitor it using high frequency ultrasound.

The present protocol describes the steps to obtain venous thrombosis using a stasis model. In addition, we are using a non-invasive method to measure thrombus formation and resolution over time.

Venous thrombosis is a common condition affecting 1 - 2% of the population, with an annual incidence of 1 in 500. Venous thrombosis can lead to death ...

Immunology and Infection

A Novel Non-invasive Method for the Detection of Elevated Intra-compartmental Pressures of the Leg

Acute Compartment Syndrome is a devastating consequence of musculoskeletal trauma. Currently the diagnosis is based on clinical signs and symptoms, and while adjuncts such as invasive intra-compartmental pressure measurements are often used to corroborate the physical exam findings, there remains no reliable objective test to aid in the decision to perform a decompressive fasciotomy. In a cadaver model of compartment syndrome, an ultrasound (US) based method has been shown to be a reliable measurement of increased intra-compartmental pressure. An absolute pressure of &#62;100 mbar or a difference of 50 mbar in the CFFP between the legs can be considered pathologic. Using an ultrasound transducer, coupled with a pressure sensor, the pressure needed to flatten the superficial fascia of the anterior compartment of lower legs (Compartment Fascia Flattening Pressure [CFFP]) can be measured. The CFFP of the injured leg is compared to the CFFP of the uninjured leg. This US measured index can then serve as an adjunct to the physical exam in evaluating injured lower extremities and assessing the need for decompressive fasciotomy. The advantages of this protocol include: being a non-invasive method and an easily reproducible technique.

An ultrasound probe coupled with a pressure sensor is used to assess the intra-compartmental pressure of the leg by directly measuring the compartment fascia flattening pressure (CFFP). This non-invasive protocol will provide reliable assessment of the pressure inside the anterior muscular compartment of the lower leg.

Acute Compartment Syndrome is a devastating consequence of musculoskeletal trauma. Currently the diagnosis is based on clinical signs and symptoms, and ...

Ultrasound Protocol for Perioperative Frailty Assessment

Identifying Frailty Using Point-of-Care Ultrasonography: Image Acquisition and Assessment

Frailty is a significant predictor of a range of adverse outcomes in surgical patients, including increased mechanical ventilation time, longer hospital stays, unplanned readmissions, stroke, delirium, and death. However, accessible tools for screening in clinical settings are limited. Computed tomography of the psoas muscle is the current standard imaging device for measuring frailty, but it is expensive, time-consuming, and exposes the patient to ionizing radiation. Recently, the use of point-of-care ultrasound (POCUS) has emerged as a potential tool to determine the presence of frailty and has been shown to accurately predict frailty and postoperative outcomes. In this article, we will describe the image acquisition of the quadriceps muscles and explain how they can be used to determine frailty and predict postoperative adverse events. We will present information on probe selection, patient positioning, and troubleshooting. Images from a demonstration will be used to present the POCUS technique and example results. The article will culminate in a discussion of the use of these images in medical decision-making and potential limitations.

Author Spotlight: Assessing Surgical Frailty with Point-of-Care Ultrasound of Quadriceps Muscles

Here, we present a protocol to assess frailty in the perioperative setting using point-of-care ultrasound to measure quadriceps thickness. This method offers a practical, non-invasive alternative to traditional assessment methods, potentially enhancing perioperative care by quickly identifying frail patients.

Frailty is a significant predictor of a range of adverse outcomes in surgical patients, including increased mechanical ventilation time, longer hospital ...

Point-of-Care Ultrasound for Peripheral Veno-Arterial Extracorporeal Membrane Oxygenation Without Left Ventricular Venting

Over the past several decades, veno-arterial extracorporeal membrane oxygenation (V-A ECMO) has become a critical tool in the management of patients with severe cardiogenic shock and cardiopulmonary failure. Due to the inherent instability of these patients, their transport away from intensive care units is fraught with risk. As a result, bedside diagnostic tools are essential for their daily care. One such tool is point-of-care ultrasound (POCUS) of the heart, which can non-invasively assess several parameters: left ventricular (LV) performance (size, systolic function, stroke volume, aortic valve opening), right ventricular (RV) performance (size, systolic function), and the presence of intracardiac thrombus. Additionally, POCUS can assist in evaluating readiness for V-A ECMO weaning and eventual decannulation. Despite its potential, the use of POCUS in the context of V-A ECMO remains inconsistent due to variability in provider training. This study aims to address this gap by detailing POCUS image acquisition in V-A ECMO, particularly in the absence of LV venting. It covers key aspects such as patient positioning, transducer selection, probe placement, acquisition sequence, and image optimization.

This protocol outlines the use of point-of-care ultrasound (POCUS) to monitor patients on peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) without left ventricular venting. It evaluates left ventricular distension, intracardiac or aortic root thrombus, and identifies useful cardiac POCUS parameters for weaning from V-A ECMO.

Over the past several decades, veno-arterial extracorporeal membrane oxygenation (V-A ECMO) has become a critical tool in the management of patients with ...

Demystifying Venous Excess Ultrasound (VExUS): Image Acquisition and Interpretation

Providers in many medical specialties must accurately assess the hemodynamic circuit to deliver appropriate patient care. Venous congestion is increasingly implicated in a range of multiorgan complications. However, hemodynamic assessment remains challenging because of the complex physiology involved and inconsistent diagnostic accuracy of conventional bedside tools and physical exam maneuvers. While right heart catheterization is regarded as the gold standard for measuring systemic venous pressure, it is invasive and not easily repeatable, and thus, there remains a need for non-invasive alternatives. Even point-of-care ultrasound examinations of the internal jugular vein or inferior vena cava have significant limitations in terms of accuracy of intravascular volume assessment and correlation with central venous pressure. To improve bedside clinicians' accuracy at assessing venous congestion, a protocol was developed and validated that utilizes pulsed-wave (PW) Doppler signals of veins in the liver and kidney to grade the degree of venous congestion present in patients. Although this scoring system, called Venous Excess Ultrasound (VExUS), is being increasingly adopted within certain subspecialties of medicine, such as nephrology and critical care, it remains underutilized in medicine as a whole. This is likely due, at least in part, to knowledge gaps and lack of training in this emerging modality. To address this educational gap, this article will describe VExUS image acquisition and interpretation.

Point-of-care ultrasound (POCUS) is often used to assess the hemodynamic circuit and detect the presence of venous congestion. The Venous Excess Ultrasound (VExUS) scoring system was developed to aid clinicians in predicting the impact of venous congestion on organ dysfunction. This article aims to describe VExUS image acquisition and interpretation.

Providers in many medical specialties must accurately assess the hemodynamic circuit to deliver appropriate patient care. Venous congestion is ...

Using Point of Care Ultrasound to Augment Acquisition of Physical Exam Skills: Knee and Shoulder

Source: Joseph H. Donroe, Rachel Liu; Yale School of Medicine, USA
Point of Care Ultrasound or POCUS is easy to use, has enhanced mobility due to the smaller equipment needed, and may be carried out in a variety of settings. It is also far safer and cheaper than imaging techniques like computer tomography.
POCUS can be helpful when certain physical exam findings are difficult to appreciate by palpation, percussion, or auscultation and can facilitate learning elements of the cardiac, pulmonary, abdominal, musculoskeletal, and vascular exams.
With ultrasound, the anatomy of the knee and shoulder are easily visualized, thus allowing a better understanding of the anatomic basis for many exam maneuvers.&#160; Ultrasound allows for the detection of tendons, ligaments, and muscle injury, the presence of fluid, structural abnormalities, and bone fractures in the musculoskeletal region.
In the case of the knee, ultrasound is helpful in the detection of injuries of the quadriceps and patellar tendons; injuries of the medial and lateral collateral ligaments; meniscal tears; effusions; degenerative changes; bursitis of the suprapatellar, prepatellar, infrapatellar, and pes anserine bursae; and other similar diseases. On the other hand, in the shoulder, ultrasound can be useful in the diagnosis of rotator cuff disease, biceps brachii injury, and acromioclavicular joint disease, among other shoulder pathologies.
Ultrasound is also a dynamic imaging modality that can highlight the movement of joints and muscles in real-time. Therefore, it can lead to the improved acquisition of exam skills when performed in conjunction with the specific maneuvers. For example, shoulder impingement syndrome can be better understood by learners of the physical exam by seeing the anatomy and dynamic movements under ultrasound.
Examination of the musculoskeletal system is a particularly difficult skill to acquire, involving the integration of the technical skills to perform specific maneuvers with the relevant clinical anatomy and physiology of joints. Overall, the integration of ultrasound with other clinical skills results in improved confidence and accuracy in the performance of the physical exam. In this video, we will demonstrate how to use POCUS to facilitate learning the examination of the knee and shoulder.

Source: Joseph H. Donroe, Rachel Liu; Yale School of Medicine, USA
Point of Care Ultrasound or POCUS is easy to use, has enhanced mobility due to the ...

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Using Point of Care Ultrasound to Augment Acquisition of Physical Exam Skills: Veins and Arteries

Source: Joseph H. Donroe, Rachel Liu; Yale School of Medicine, USA
Vascular diseases make up most cases of emergency hospitalization and carry a high mortality risk. Point-of-care ultrasound or POCUS enables accurate diagnosis of these diseases and shortens the time between detection of the cause and selection of appropriate treatment strategies, thus, reducing the patient mortality rate. POCUS offers a safe, low-cost, and less invasive bedside tool for examining arteries and veins, besides its many other applications.
For learners, the anatomical difference between arteries and veins can also be better understood with the help of POCUS. Arteries are thicker walled and pulsatile; veins are thinner walled, may have valves, and collapse when compressed.
Arteries may be difficult to palpate if they are deeper, have reduced blood flow, or a practitioner does not know the anatomic landmarks or is inexperienced. During an examination, while palpation enables an understanding of the intensity, symmetry, and rhythm of blood flow, POCUS can provide exact information on the underlying anatomy and location of the blood vessels. For example, the dorsalis pedis is a major artery that runs over the dorsal foot. It can become impalpable if the flow is obstructed. In such a condition, POCUS can help to detect the absence of blood flow.&#160;
Consider the internal jugular vein or IJV, which drains venous blood from the brain and superficial veins of the face and finally delivers the blood to the right atrium of the heart. Visualization of the internal jugular vein under ultrasound can improve inspection for jugular venous distension.
Among the arteries, the aorta is the main artery that carries oxygenated blood from the heart and branches off to deliver blood to the rest of the body. The portion of the aorta that passes through the abdomen, from the diaphragm to the umbilical area, is known as the abdominal aorta. The abdominal aorta is examined using POCUS to diagnose life-threatening conditions such as abdominal aortic aneurysm&#8212; a swelling in the aorta, or aortic dissection&#8212; a tear in the artery.&#160;
The conceptual knowledge of the vascular system combined with the technical skills of using palpation and ultrasound can help make life-saving diagnoses during physical examination.
In this video, we will demonstrate how to use POCUS to facilitate learning the examination of veins and arteries.

Source: Joseph H. Donroe, Rachel Liu; Yale School of Medicine, USA
Vascular diseases make up most cases of emergency hospitalization and carry a high ...

Peripheral Vascular Exam

Source: Joseph Donroe, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT
The prevalence of peripheral vascular disease (PVD) increases with age and is a significant cause of morbidity in older patients, and peripheral artery disease (PAD) is associated with cardiovascular and cerebrovascular complications. Diabetes, hyperlipidemia, hypertension, and tobacco use are important disease risk factors. When patients become symptomatic, they frequently complain of limb claudication, defined as a cramp-like muscle pain that worsens with activity and improves with rest. Patients with chronic venous insufficiency (CVI) often present with lower extremity swelling, pain, skin changes, and ulceration.
While the benefits of screening asymptomatic patients for PVD are unclear, physicians should know the proper exam technique when the diagnosis of PVD is being considered. This video reviews the vascular examination of the upper and lower extremities and abdomen. As always, the examiner should use a systematic method of examination, though in practice, the extent of the exam a physician performs depends on their suspicion of underlying PVD. In a patient who has or is suspected to have risk factors for vascular disease, the vascular exam should be thorough, beginning with inspection, followed by palpation, and then auscultation, and it should include special maneuvers, such as determining the ankle brachial index. Maneuvers that make use of a handheld Doppler are demonstrated in a companion video.
<img alt="Figure 1" src="/files/ftp_upload/10122/10122fig1.jpg" /> 
Figure 1. The major arm and leg arteries.

Peripheral Vascular Exam and Major Arm and Leg Arteries

Source: Joseph Donroe, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT
The prevalence of peripheral vascular disease (PVD) ...

Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis

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