FAST Exam

1. FAST Exam Erin Carnes September 27, 2007

2. FAST Exam • Introduction • Ultrasound Physics • Technique • Indications for FAST exam • Performing a FAST exam • Limitations • Questions

3. What is the FAST exam? • Focused Assessment by Sonography in Trauma • Focused exam using ultrasound to diagnose hemorrhage in a trauma setting • Ideally takes < 3 min • 4 primary views • RUQ • LUQ • Subxiphoid • Suprapubic

4. Basic Ultrasound Physics • Ultrasound is a spectrum of sound frequencies above the human hearing range. • Molecules must be present for sound to exist. • Every object has an echogenicity. When sound waves hit the object some are transmitted through and some bounce back. • Every substance will respond differently to the sound waves striking it’s surface. This occurs at every sound-to-sound interface and the reflection of sound waves can be used to create and image.

5. Technique • Goal: to identify blood in body cavities where it is not supposed to be • Unclotted blood appears black on US • Clotted blood appears gray • Abdominal probe with small footprint (between 1- 3 cm) with range of frequency between 2.0 Hz and 5.0 Hz • Scan 4 areas • RUQ • Subxiphoid • LUQ • Suprapubic

6. Indications • Blunt thoracoabdominal trauma • Penetrating thoracoabdominal trauma • Suspected pericardial tamponade • Trauma patient with hypotension on unknown etiology • Thoracoabdominal trauma in a pregnant patient

7. Right Upper Quadrant • Sagittal view obtained by placing probe either in the midclavicular line on the lower rib cage or below the right costal margin • May have to move probe laterally to avoid gas in hepatic flexure • Air-filled lung creates reflection artifact in which lung appears to be composed of liver parenchyma • Scan for black fluid in potential spaces

8. Normal RUQ

9. Abnormal RUQ

13. Subxiphoid • Probe placed under xiphoid almost parallel with skin surface directed towards patient’s left shoulder • Parasternal view may be used when supxiphoid unable to be obtained • Consider pnuemothorax when unable to obtain images of heart and no apparent reason

14. Normal Subxiphoid

15. Abnormal Subxiphoid

17. Left Upper Quadrant • Most technically difficult to obtain • Probe placed parallel with ribs in posterior axillary line • Scan potential spaces between diaphragm and spleen and spleen and kidney for free fluid

18. Normal LUQ

19. Abnormal LUQ

23. Suprapubic • Entire pelvis should be scanned from top to bottom with transducer in transverse place and them side to side with transducer in sagittal plane • Pouch of Douglas is the most dependent site in peritoneal cavity • First sign of blood is often two small black triangles on either side of rectum • “Bow tie sign”

24. Normal Suprapubic

25. Abnormal Suprapubic

29. Limitations • Retroperitoneal bleeding • Inadequate volume of fluid • Not enough time elapsed since trauma to demonstrate bleeding • Solid organ trauma with encapsulated bleeding • Image quality dependent on quality of US machine and probe, body habitus of patient, physical injuries • Scan and interpretation are operator dependent

30. Questions?