A Techy Triage Technique: the FAST Scan
The ultrasound machine is quickly becoming a popular device in animal hospitals.
Unlike in years past, ultrasound equipment is not necessarily cost- or space-prohibitive for veterinary professionals. In fact, you can now buy an ultrasound probe that plugs into your laptop or your smartphone (sound the nerd siren)!
Now, I’ve done the math. Not every hospital has a board-certified radiologist to interpret formal ultrasound exams. Veterinarians are nonetheless using these devices and looking for ways to use them with limited training and in an evidence-based manner.
Enter the FAST Scan
FAST (Focused Assessment with Sonography for Trauma) is essentially the non-radiologist use of ultrasound during assessment of emergency patients.
FAST was originally developed for one purpose: the detection of free abdominal, pleural, or pericardial fluid following trauma. But with proper training, FAST has proven useful in diagnosing an array of other emergency conditions.
In human medicine, FAST scans have been a standard of care screening technique in emergency rooms since the 1990’s. In fact, our emergency and surgery physician counterparts now receive formal training in this point-of-care technique. Since 2004, several animal studies have guided the development of veterinary versions of the FAST scan.
In veterinary medicine, FAST is becoming popular as a surprisingly easy to learn and effective procedure that permits rapid clinical decisions and facilitates accurate pet owner education.
How Do You Use the FAST Scan in Practice?
In animals, diagnosing the extent of injury following trauma or similar emergent situations can be challenging for veterinarians and financially draining for pet owners.
Does your practice have a basic ultrasound machine and rubbing alcohol? Then you can help these patients by learning the FAST scan.
Recently, the “T” in FAST has been used to represent “Triage” and “Tracking” as well as “Trauma”. This highlights FAST’s usefulness in nontraumatic cases such as acute abdomens, collapse, weakness, disorientation, shock-like emergencies, and respiratory distress patients.
One last note: the FAST scan is not meant to replace a thorough physical examination, radiographic studies, or ultrasonographic evaluation by a board-certified radiologist. Rather, FAST is used as an extension of your physical exam during assessment of emergent patients.
How Do You Perform a FAST Scan?
Two procedures are described in animals based on anatomic location scanned: abdominal FAST (AFAST) and thoracic FAST (TFAST). For both procedures, animals are placed in right lateral recumbency initially, unless unstable due to respiratory disease (then use sternal recumbency). Dorsal recumbency is never used. No shaving is necessary for FAST scans and either gel or alcohol can be used to part the fur.
AFAST (Abdominal FAST) Technique
Four specific sites are quickly assessed for obvious fluid pockets. S can in order and using longitudinal views:
(DH) Diaphragmatic-Hepatic— view of gall bladder, pleural, and pericardial spaces
(SR) Spleno-Renal — window into the retroperitoneal space
(CC) Cysto-Colic — helps orient via the easily identifiable urinary bladder
(HR) Hepato-Renal — AKA “homerun” site (most likely to contain fluid for sampling)
TFAST (Thoracic FAST) Technique
This exam is more technically demanding to learn. Five specific sites are scanned for evidence of a pleural effusion, pericardial effusion, pulmonary disease, or signs consistent with a pneumothorax. The CTS view below is used on both sides of the chest. The PCS view is considered two sites (view in both longitudinal and transverse by rotating probe). Scan all views on left side first, then sit patient sternal and examine right CTS site:
(CTS) Chest Tube Site — rule out pneumothorax and survey for lung disease
(PCS) Pericardial Site — survey pleural or pericardial effusions and cardiac disease
(PCS) Pericardial Site (transverse view)
(DH) Diaphragmatic-Hepatic — evaluate pleural or pericardial effusions
(CTS) Chest Tube Site (opposite side of chest)
Advanced uses of these techniques such as the Vet BLUE (Bedside Lung Ultras ound Exam) and an Abdominal Fluid Scoring System have also been described in recent literature.
Where Can I Find More Information?
A thorough guide on how to perform and interpret FAST scans can be found in prospective studies for TFAST (2008), AFAST (2009), and a clinical practice review (2011) published in the Journal of Veterinary Emergency and Critical Care. Easy-to-understand explanations with clear diagrams and decision trees are included.
Additionally, Clinician’s Brief has published an article on FAST.
The Veterinary Information Network (VIN) contains FAST scan proceedings from recent International Veterinary Emergency and Critical Care Society (IVECCS) conferences.
Wet lab courses are also being offered at the annual IVECCS conference.
Finally, FASTvet.com is a new website with more information including the forthcoming veterinary textbook, Focused Ultrasound Techniques for the Small Animal Practitioner by Dr. Gregory Lisciandro.
About the Author
Dr. Caleb Frankel is an ER veterinarian, author, speaker, and entrepreneur. He currently divides his time between two roles: emergency veterinarian at VSEC, a 70-doctor referral hospital in Greater Philadelphia, PA (USA) and the founder of Instinct Science, a new animal health company helping the world’s state-of-the-art veterinary practices streamline their care through medically-driven invoicing and thoughtful automation.
He served as Director of New Product Development at Brief Media for 4 years where he lead the development and launch of products such as Plumb's Veterinary Drugs and New York Vet. Follow Dr. Frankel on Twitter @VMDtechnology.