Dr. Laura Weber’s Case of the Week!

HPI: The patient is an 81 y.o. female with PMH of colon cancer s/p recent colectomy who presents with dyspnea on exertion, palpitations, and left lower extremity swelling. Patient was found to be hypoxic to 89% on RA and had left leg swelling with tenderness to palpation of posterior calf.

ED US: 

The Basics:  Clots in the deep venous system of the lower extremities pose significant risk of pulmonary embolism. Major branches of the deep venous system in the lower extremity include the common femoral vein (CFV), superficial femoral vein (SFV), and popliteal vein. The CFV is formed by the deep femoral vein (DFV) and SFV. The great saphenous vein (GSV) drains into it caudally. The popliteal vein is formed by the confluence of the anterior tibial, posterior tibia, and peroneal veins. Blood clots are most likely to occur at junctions of veins. Therefore, the limited compression DVT study must include the CFV at the GSV junction to the SFV and DFV bifurcation and popliteal vein to the popliteal trifurcation.

The Protocol:
·   A high frequency vascular probe (6-10 Hz) should be used. If the patient has a lot of overlaying tissue, a lower frequency curvilinear probe can be used. The patient should be positioned in the reverse Trendelenburg position with their hip in mild external rotation and knee slightly bent. This position will maximize the distension of the leg veins.
·  Evaluation is done by compressing the veins with the probe perpendicular to the patient and assessing for complete apposition of the anterior and posterior walls of the vessels. Inability to completely compress the vein suggests a clot. The clot itself may be visible in the vein as echogenicity within the lumen.
·   Other techniques that can give further information about the patency of the vessel:

  1. Color-flow Doppler can demonstrate a lack of flow in the vessel or a filling defect.
  2. Respiratory phasicity is a technique where pulsed wave Doppler is superimposed on top of the vein to observe the respiratory variation of blood flow in the vein. A lack of normal respiratory variation may be suggestive of clot impeding flow proximal to the level evaluated.
  3. Augmentation is a technique where the provider squeezes the calf briskly below the level of suspicion while visualizing the vessel with pulse Doppler imaging. A corresponding burst represents a patent vessel. If there is no burst, it is suggestive of a completely obstructive clot distal or at the level visualized. However, studies have shown that there is a lack in clinical benefit of this technique and that it may cause unnecessary discomfort in patients.

Hospital Course: After the positive DVT study in the ED, the patient was started on anticoagulation and admitted to the ICU. The patient remained stable and was weaned off from supplemental oxygen by hospital day two and subsequently discharged by hospital day six on Eliquis.

References: 
Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014.” WikiJournal of Medicine 1(2).DOI:10.15347/wjm/2014.010. ISSN 2002-4436.

Dean, Anthony J, and Bon S Ku. “Section Links.” Deep Venous Thrombosis, ACEP, www.acep.org/sonoguide/dvt.html.

Lockhart, Mark E, et al. “Augmentation in Lower Extremity Sonography for the Detection of Deep Venous Thrombosis : American Journal of Roentgenology : Vol. 184, No. 2 (AJR).” American Journal of Roentgenology, vol. 184, no. 2, Feb. 2005, pp. 419–422., www.ajronline.org/doi/full/10.2214/ajr.184.2.01840419.

Rios , Marina Del, et al. “ACEP.” Focus On: Emergency Ultrasound For Deep Vein Thrombosis // ACEP, Mar. 2009, www.acep.org/Clinical—Practice-Management/Focus-On–Emergency-Ultrasound-For-Deep-Vein-Thrombosis/#sm.0000d1ebcfwu3dj3ycw1vqtn6irgs.

Schott, Christopher. “DVT Ultrasound: Augmentation Technique.” Critical Care Medicine DVT Ultrasonography, Sonoguide’s Critical Care Ultrasound, 21 Aug. 2013, www.youtube.com/watch?v=pjkaFr24xGw.