range of frequencies, known as bandwidth. In choosing the best frequency, we need to go back to basics. Remember that higher frequencies are attenuated more and that means less penetration but better detail. Lower frequencies are attenuated less and that means deeper penetration but less detail. Another rule of thumb is that the smaller the patient or area of interest, the higher the frequency (MHz) versus the larger the patient or area of interest, the lower the frequency (MHz).
Setting Up an Ultrasound Program
See Chapter 45 for additional information.
Pearls and Pitfalls, The Final Say
In summary, these first four chapters have briefly covered some of the ultrasound basics. Other textbooks are available that go into more detail regarding ultrasound principles and artifacts, and many courses sponsored by ultrasound companies are available throughout the year to enhance learning. FASTVet.com is an online Global FAST education company. Another resource is the International Veterinary Point‐of‐Care Ultrasound Society's website www.IVPOCUS.org
It is important to be familiar with some of the basic principles, artifacts, and nuances associated with ultrasound as an imaging modality for your busy general practice, emergency room, or critical care unit to minimize misinterpretations. POCUS and FAST ultrasound are truly an “extension of the physical examination” and “the modern stethoscope” (Rozycki et al. 2001; Filly 1988).
So there you have it. Turn on your ultrasound machine, apply your coupling medium, and start scanning. Get POCUS and FAST and better pick your next test, more accurately treat, and better keep alive your patients for gold standard testing and treatment. POCUS and FAST save lives!
References
1 Bahner DP, Blickendorf JM, Bockbrader M, et al. 2016. Language of transducer manipulation. J Ultrasound Med 34:183–188.
2 Evans DH, McDicken WN, Skidmore R, Woodcock JP. 1989. Doppler Ultrasound: Physics, Instrumentation, and Clinical Applications. Chichester: Wiley.
3 Filly RA. Ultrasound: the stethoscope of the future, alas. Radiology 167:400.
4 Nyland TG, Mattoon JS, Herrgesell EJ, et al. 2002. Physical principles, instrumentation, and safety of diagnostic ultrasound. In: Small Animal Diagnostic Ultrasound, 2nd edition, edited by Nyland TG, Mattoon JS. Philadelphia: WB Saunders, pp 1–18.
5 Pozniak MA, Zagzebski JA, Scanlan KA. 1992. Spectral and color Doppler artifacts. Radiographics 12:35–44.
6 Rozycki GS, Pennington SD, Feliciano DV, et al. 2001. Surgeon‐performed ultrasound in the critical care setting: its use as an extension of the physical examination to detect pleural effusion. J Trauma 50:636–642.
Chapter Five POCUS: Top Ultrasound Mistakes During Global FAST
Gregory R. Lisciandro
Introduction
Having trained close to 1000 veterinarians from around the world in Global FAST, AFAST, TFAST, and Vet BLUE, we have come up with our top list for image acquisition and interpretation mistakes made during Global FAST that will help synthesize the previous three excellent chapters by Dr Fulton. Whichever machine you work with, you must understand its software, how it interprets artifacts, and what its strengths and weaknesses are to gain full confidence in its imaging potential. You also need to know how to optimize image acquisition by taking advantage of external patient features and the role your hands should play. This takes time, repetition, and critical thinking during image acquisition and a sonographer who dares to use the different buttons and controls on the machine.
We strive to perform the entire Global FAST using the abdominal preset with the same curvilinear (microconvex) probe for the abdomen and thorax, including heart and lung. However, in time the sonographer may come to prefer different presets (cardiac, small parts) and probes (phased‐array, linear), depending on the structure(s) of interest, the stability of the patient and the clinical questions being addressed. However, the curvilinear (microconvex) probe is absolutely acceptable for the entire Global FAST examination.
What POCUS Top Mistakes Can Do
Make the sonographer aware of the most common mistakes which occur during Global FAST image acquisition.
Make the sonographer aware of the most common air and fluid‐associated artifacts and where they commonly occur during Global FAST.
By raising awareness of these mistakes during Global FAST, the sonographer will carry over these principles to other ultrasound studies.
What POCUS Top Mistakes Cannot Do
Cannot replace proper ultrasound training and experience.
Indications
For all sonographers performing Global FAST for a basic understanding of how to optimize image acquisition and avoid mistaking artifacts for abnormalities.
Objectives
Provide a basic understanding of Global FAST ultrasound image acquisition to help accelerate the learning process.
Provide a practical approach for image optimization and artifact identification as they pertain to the standardized examination of Global FAST and its 15 acoustic windows, and to help make your ultrasound interpretation more accurate.
Image Acquisition Mistakes
Not Recognizing Air Trapping
Ultrasound does not transmit through air. Air reflects your ultrasound beam from its path from the probe head to your areas of interest. Optimizing image quality relies on eliminating the phenomenon of “air trapping,” especially the air trapped between the probe head and its contact with the patient’s skin (Figures 5.1 and 5.2). Air trapping is potentially more problematic when not clipping hair, and hair is rarely clipped for Global FAST, AFAST (abdomen), TFAST (pleural cavity, heart, and lung), and Vet BLUE (lung). So be sure to part the hair, part the hair, part the hair! Parting the hair gets the probe in direct opposition to skin and the best image is optimized with the probe head directly on skin, with no hair in between, and with ample acoustic coupling medium. So what do we recommend?
70% isopropyl alcohol helps strip out air and lipids from hair follicles and is used for that reason. We use 70% isopropyl alcohol unless electrical defibrillation is anticipated (it’s a burn/fire hazard in the presence of electrical current and 100% oxygen) followed by alcohol‐based hand sanitizer, a brilliant trick of the trade given to me several years ago by the Mississippi State radiologist Dr Jennifer Gambino.
