2. FAST (Edited).ppt introductory lecture on FOCUS
- 1. FAST AND E-FAST Tilahun Jiru MD Asst prof of EM & CC
- 2. Clinical Case GR is a 62 y male who hit his right torso when he slipped on an icy sidewalk. He denies head trauma, and can walk without a limp. Two hours later the pain in his lower chest has increased he comes to the ED.
- 3. Clinical Case PE: BP 80/50, pulse109, RR 24 , SO2 88% There is a minor abrasion to right lateral chest, which is tender to palpation. Diffuse mild abdominal tenderness. Meds: warfarin for irregular heartbeat (AF)
- 4. Clinical Case 2 large IV’s placed, CXR done. Blood tests sent. Bedside ultrasound done. CXR revealed lower rib fractures, no HTX or PTX In trauma patients, we don’t consider neurogenic, obstructive, or distributive shocks without first ruling out presence of hemorrhage. Areas in our body where we can bleed and go into shock include: -intraperitoneal, retroperitoneal, thorax, pericardial space, pelvis, external bleeding, femoral triangle/long bones, skull (very rare & not common in adults; but in pediatrics, especially infants can develop Shock from skull bleeding) The retroperitoneal space can accumulate up to 3 liters of blood. Blood in Morison’s pouch
- 5. Clinical Case Blood ordered and OR notified. He is found to have a liver laceration and 1500 cc of blood in the peritoneal cavity.
- 6. Diagnostic Modalities in Blunt Abdominal Trauma Diagnostic Peritoneal Lavage (DPL) CAT Scan Ultrasound (FAST exam)
- 7. DPL When we suspect an intra-abdominal collection Initially, we try to tap with dry needle. If we take out 10 ml of fresh blood => Positive (intra-abdominal collection) If nothing comes out into the needle (and needle remains dry) => we flush with ~1000 ml of NS, take it back with the needle, and analyze the fluid => if we get >100,000 RBC => Positive (intra-abdominal collection) Usually done around the umbilicus Cannot identify specific viscus injuries (it just identifies whether there is collection or not, without knowing the origin) DPL is an old method and it is outdated – replaced by US
- 8. Diagnostic Peritoneal Lavage Advantages Very sensitive for identifying intra- peritoneal blood 100,000 RBC/mm3 approx or 10 ml fresh blood Can be done at the bedside Can be done in 10-15 minutes Disadvantages Overly sensitive, may result in too high a laparotomy rate Invasive Difficult in pregnancy, or with many prior surgeries (because it is a blind procedure, we can puncture intra-abdominal organ) Can not be repeated (we cannot puncture again and again) Does not help to examine for retroperitoneal collection
- 9. CT-SCAN The gold standard for examining for an intra-abdominal injury.
- 10. CT Scan Advantages Identifies specific injuries Good for hollow viscus and retroperitoneal injury Best for retroperitoneal collection High sensitivity and specificity (gold standard) Disadvantages Expensive equipment 30-60 minutes to complete study Only for stable patients Not for pregnant patients (unless a must, where we have to give priority for mother’s life) We may use contrast, which can cause AKI.
- 11. There are 2 types of organs in the abdomen – solid and hollow. The presentations from the injuries of these different types of organs is different. Solid organ injury => blood collection Hollow viscus injury => peritonitis; (there would not be an overt collection; even if there is collection, instead of RBC, WBC and GI content would be detected). Thus, for such injury, DPL is not helpful. CT advantageous for such occasion.
- 12. FAST Has 4 components (Dependent areas that should be scanned): - Pericardium (sub-xiphoid view) – to look for pericardial collection. Pericardial collection can cause obstructive shock. 50-150 ml of acute bleeding into the pericardium can cause obstructive shock. We visualize the pericardium under the xiphoid. - Right upper quadrant (hepato-renal view) – to look for collection in Morison’s pouch. - Left upper quadrant (spleno-renal view) – - Pelvis Focused Abdominal Sonography in Trauma
- 13. The most common intra-abdominal organ to be injured by blunt trauma is the spleen. By penetrating trauma => liver
- 14. FAST Advantages Can be performed in 5 minutes at the bedside (the equipment is very portable) Non-invasive (no radiation; no contrast) Repeat exams Sensitivity and specificity for free fluid almost equal to DPL and CT Disadvantages Operator dependent May not identify specific injury (we cannot tell which organ is injured) Poor for hollow viscus or retroperitoneal injury (air is an enemy of US wave) Poor for diaphragmatic, duodenal, and pancreatic injuries (CT good for these, but still not the best. For diaphragmatic injury the best diagnostic modality is laparoscopy. For pancreas => CT still best) Obesity, subcutaneous air (from a concomitant chest injury) may interfere with exam We cannot differentiate whether the collection is blood or another type of fluid (e.g., urine)
- 15. FAST Principles Detects free intraperitoneal fluid Blood/fluid pools in dependent areas Pelvis Most dependent Hepatorenal fossa Most dependent area in supramesocolic region
- 16. FAST- principles Intraperitoneal fluid may be Blood Preexisting ascites Urine Intestinal contents
- 17. FAST – limitations US relatively insensitive for detecting traumatic abdominal organ injury We cannot estimate the volume of fluid collected Fluid may pool at variable rates Minimum volume for US detection (250 ml) Multiple views at multiple sites Serial exams: repeat exam if there is a change in clinical picture If our initial scan is normal, it doesn’t rule out collection. Because, blood collection is an ongoing process; it doesn’t collect at one time. Operator dependent
- 18. Protocol: + Pericardial fluid OR Stable CT +IP fluid unstable OR There are CT indications for laparotomy. If patient has stable VS with positive FAST, we have to identify and grade the injury with CT. There are gradings of hepatic, renal, splenic… injuries.
- 19. FAST Perform during Resuscitation (in ATLS, we can do FAST at C (circulation) or at E (exposure)). Physical exam Stabilization
- 20. Equipment Curved array Various “footprints” Small footprint for thorax Large for abdomen Variable frequencies 5.0 MHz: thin, child 3.5 MHz: versatile 2.0 MHz: cardiac, large pts There are different types of probes: Abdominal/curved probe – used to visualize for deep collection. The resolution is poor. High-depth-low-resolution. Vascular/straight probe – low-depth, high- resolution
- 21. Time to Complete Scan Each view: 30-60 seconds Number of views dependent on clinical question and findings on initial views Total exam time usually < 3-5 minutes
- 22. Focused Abdominal Sonography for Trauma (FAST) Consists of 4 views Subxiphoid Right Upper Quadrant Left Upper Quadrant Pouch of Douglas
- 23. FAST Increased sensitivity with increased number of views Will identify pleural effusions Reliably detects as little as 50-100cc in the thorax (CXR – 200 to 250 ml). US is more sensitive in detecting both pneumo- & hemo-thorax than X-ray.
- 24. Clinical experience with FAST Intraperitoneal fluid Sensitivity 82-98%, specificity 88-100% Increased sensitivity with Increasing number of views Trendelenberg Serial examinations Can detect as little as 250cc of free fluid
- 25. RUQ Probe at right thoraco- abdominal junction Liver : used as a large acoustic window (bc liver is filled with parenchyma and blood, which are good in transmitting US wave) Probe marker/indicator should be pointing upward (cephalad) or to the right side. Rib interference? (avoid) Rotate 30° counterclockwise
- 26. Scan Plane Same image if probe positioned Anterior Mid axillary Posterior
- 27. RUQ Image on screen: Liver cephalad Kidney inferiorly (hyper- echoic medulla + hypo- echoic cortex + renal sinus + capsule) Morison’s Pouch*: space between Glisson’s capsule and Gerota’s fascia * * * *
- 28. Normal RUQ Image kidney Longitudinally Transversely Two toned structure Cortex/medulla Renal sinus
- 29. Appearance of blood Fresh blood Anechoic (black) Coagulating blood First hypoechoic Later hyperechoic
- 30. Normal Morison’s Pouch Free fluid in Morison’s Pouch
- 32. Always, before ruling out collection, we have to check the inferior border of the kidney, because that’s the most dependent area.
- 36. All Fluid is not Blood Ascites Ruptured Ovarian Cyst Lavage fluid Urine from ruptured bladder
- 37. Pitfalls RUQ Not attempting multiple probe placements Not placing the probe cephalad enough to use the acoustic window of the liver Scanning too soon before enough blood has accumulated Not repeating the scan
- 38. LUQ Probe at left posterior axillary line Probe indicator should be place upward Near ribs 9 and 10 Angle probe obliquely (avoid ribs) More posteriorly than for RUQ
- 39. LUQ Scan Plane More difficult Acoustic window (spleen) is smaller than liver Mild inspiration will optimize image Bowel interference is common
- 40. LUQ Scan spleen kidney *Splenorenal fossa – a potential space * * * *
- 42. More of sub-diaphragmatic than spleno-renal
- 46. To Evaluate the Thorax (E- FAST) Move probe cephalad longitudinal Image Liver Diaphragm Pleural space
- 47. Hemothorax liver diaphragm fluid Spine should not extend beyond the diaphragm. bc above diaphragm, normally there is air/lungs. If fluid collection in thorax => US wave can pass => spine can be seen (Spine Sign)
- 48. Small Pleural Effusion Large Pleural Effusion
- 49. Lung Scanning for Pneumothorax “ “Bat” Sign Bat” Sign Comet tails Comet tails Air accumulates anteriorly in the pleura. Therefore we use the vascular/ straight probe. We place the probe longitudinally. Normal findings: •Pleural movement (lung sliding) – movement of the pleural line •Comet tails – short vertical lines arising from pleura. When patient breaths, these lines move. •M-mode tracing – Sea-shore appearance Pleural line
- 51. Pneumothorax No comet tails. Plus there would be no movement.
- 52. M-mode tracing 04/25/25 fast and ED radiography 52 There is a key/button for M-mode on the machine. After placing the probe, when we touch the mode, we’ll find the above tracing. In the normal tracing, the horizontal lines do not continue up to below, Whereas in pneumothorax M-mode tracing, the lines continue downward. Normal - Sea-shore Pneumothorax – Barcode or stratosphere sign
- 53. Pelvic View Probe should be placed in the suprapubic position Either can be transverse or longitudinal Helpful to image before placement of a Foley catheter
- 54. Pelvis (Long View) Full bladder is the acoustic window
- 57. Blood in the Pelvis
- 60. Penetrating Cardiac Trauma Pericardial effusion May develop suddenly or surreptitiously May exist before clinical signs develop Salvage rates better if detected before hypotension develops
- 61. Clinical Case QD is 37 year old male brought in by EMS for ingesting entire bottle of unidentified red and white pills. In the ambulance bay he pulls out a knife and stabs himself in the left nipple.
- 62. Clinical Case Initial BP 116/72, pulse 109 RR 24. IV’s placed. No JVD, Clear breath sounds, non tender abdomen As CXR is about to be done, pulse increases to 134. Bedside ultrasound is done while cartridge is developed.
- 63. Clinical Case
- 64. Clinical Case Patient is taken to the OR Penetrating cardiac wound is repaired
- 65. Subcostal View Most practical in trauma setting Away from airway and neck/chest procedures Also called Sub- Xyphoid view
- 66. Subcostal View
- 67. Subcostal View We expect fluid bn epicardium (visceral pericardium) and parietal pericardium. A single normal US finding doesn’t rule out injury. We’ve to do it serially. normal
- 74. Avoid Pitfalls Normal echo does not definitively rule out major pericardial injury Repeat echo with clinical picture Epicardial fat pad may easily be misinterpreted as “clot” Hemothorax may be confused with pericardial effusion
- 75. The most important preoperative objective in the management of the patient with trauma is to ascertain whether or not laparotomy is needed, and not the diagnosis of a specific organ injury”