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5 scanning for dvt


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Scanning for DVT

Published in: Health & Medicine, Technology
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5 scanning for dvt

  1. 1. DVT ultrasound SAH & RNSH 2011 Critical Care Ultrasound CourseThanks to Cindy Lucas… and yet again to Daniel Lichtenstein 1
  2. 2. DVT! Anatomy! Below knee DVT?! Compression US: ! Technique ! Sites! What the scan can tell you! Pitfalls
  3. 3. Anatomy of the deep veins
  4. 4. Anatomy of the deep veins Below the knee Above the knee!Anterior tibial ! Popliteal Vein in popliteal fossa!Posterior tibial ! From confluence of 3 calf!Peroneal veins!Gastrocnemial ! To adductor canal!Soleal ! (Superficial) Femoral ! Profunda Femoris joins 4cm below inguinal!Variable ligament!Paired ! Common Femoral!Tricky! ! Long/ great saphenous!Relevance of DVT?
  5. 5. Here’s the problem It would be nice to scan But it’s hard! the below knee veins ! Variable!Incr sensitivity ! Paired!Incr accuracy ! Tiny ! Tricky!Variable ! And most of them don’t ermbolize!Paired ! (But some do…)!Tricky!!Relevance of DVT?
  6. 6. Previous top tip: justlook for above knee Leave the calves to the sonographers! 6
  7. 7. But Lichtenstein came up with a solution! Except for the anterior tibials, the below knee veins travel all in a line, a couple cm below the interosseous membrane! together with their arteries: 2 veins for each artery = 6 vessels, all lined up! We can see them from the front of the leg!! Probe between the tibia & fibula
  8. 8. Now we have 2 options1. Just above knee: leave the calves to the sonographers!2. Below knee (anterior approach) 8
  9. 9. DVT scan:Technique 9
  10. 10. Probe & preset?! Ideally linear probe / vein preset! But curved probe / FAST preset works too! Don’t need Doppler
  11. 11. Compression US! Probe in transverse position! Just squash the vein!! If it squashes easily & completely, there is no DVT! If it doesn’t, there’s a DVT
  12. 12. Normal veins! Completely compressible! Press hard enough to just indent the artery
  13. 13. Features of DVT! Gold standard sign: vein not completely compressible! You might see thrombus! Vein might fail to augment on Doppler
  14. 14. Test 1 6
  15. 15. DVT?
  16. 16. DVT?
  17. 17. DVT?
  18. 18. DVT?
  19. 19. DVT?
  20. 20. DVT?
  21. 21. DVT?
  22. 22. Compression US! Pros Cons! Easy ! Misses external iliac DVT! Rapid ! Misses small non-! B mode only occlusive DVT! 98% sensitive
  23. 23. Which sites can I compress? 2 3
  24. 24. Which sites can I compress?! Internal Jugular V! Subclavian V! IVC! Saphenofemoral confluence (up fem)! Lower (superf) femoral near adductor hiatus! Long saphenous V! Short saphenous V! Popliteal vein & trifurcation! Beloe knee veins
  25. 25. Which sites should I compress?! Up to you! The more veins you scan, the more sensitive you are… eg UL veins add 4% in PE! The fewer you scan, the less irritating it is! 3-point scan is reasonable 1. Upper femoral (confluence) 2. Lower femoral (near adductor hiatus) 3. Popliteal (irritating if supine) …or …below knee (weird at first)
  26. 26. 1: Groin! Probe in transverse position! Start just below inguinal ligament! ‘Mickey Mouse’ sign ! Femoral A ! Saphenofemoral confluence ! Then compress
  27. 27. 2: insertion of LSV / GSV
  28. 28. 2: insertion of LSV / GSV
  29. 29. 3: fem V just above knee! Adductor hiatus! Medial to the bone! Hand behind, presses forward
  30. 30. 4: popliteal fossa! Lie patient on side, or lift leg! Popliteal vein ! Superficial to popliteal artery ! visualise bone beneath ! follow it to the trifurcation
  31. 31. 5: below the knee! Supine patient! Probe transverse! Between tibia & fibula
  32. 32. Handy Hints as you go down the leg1. Decrease greyscale (dynamic range)2. Decrease frequency3. Increase depth as you go4. Obese: change to curved probe5. Sit with legs over bed / stand up6. Valsalva (humming works)7. Doppler …
  33. 33. Pitfalls! Duplicate venous systems (duplex popliteal up to 35%)! Non occlusive thrombus! LSV, SSV! Ant tibial veins! However … ‘90% = 100%’
  34. 34. One more time: Handy Hints ! You don’t need Doppler ! You don’t need linear probe ! But you won’t be 100% ! Below-knee isn’t that hard ! Sitting up / standing ! Valsalva (humming works)
  35. 35. DVT US: Summary! Compression US! Groin! Just above knee! Below knee