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Applications for US in the ED setting continue to undergo rapid
growth, both in the U.S. and internationally. Clinicians who practice
in the ED, the critical-care setting, and other acute care settings
clearly recognize emergency bedside US’s ability to improve
and expedite patient care. Emergent indications for ED US center
on detecting and screening for trauma or pneumothorax, cardiac arrest
states, abdominal aortic aneurysm (AAA), and ectopic pregnancy,
and assistance with vascular access. Urgent indications for ED US
include screening for biliary or renal disease and deep venous thrombosis
(DVT). US also may assist with the detection and drainage of soft
tissue abscesses. Numerous other applications for ED US—including
general surgical, testicular, ocular, and procedural guidance—are
available, but are beyond the scope of this chapter.
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The focused assessment with sonography for trauma (FAST) examination
is a bedside screening tool to aid clinicians in identifying free
intrathoracic or intraperitoneal fluid. The underlying premise behind
the use of the FAST examination is that clinically significant injuries
will be associated with the presence of free fluid accumulating
in dependent areas. The FAST examination was developed as a limited
US examination, focusing primarily on the detection of free fluid,
and was not designed to universally identify all sonographically
detectable pathology. Although a number of groups have subsequently
recommended additions or modifications to the standard FAST examination,
such as evaluating for pneumothoraces, quantifying the degree of
free intraperitoneal fluid present, or following the accumulation
of the free fluid, the essence of the examination remains identifying
findings that can be interpreted by clinicians in a clinical context.
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Ultrasonography offers several advantages over diagnostic peritoneal
lavage and CT. Numerous studies have demonstrated that the FAST
examination is an accurate screening tool for abdominal trauma.1–9 Advantages
of the FAST examination are that it is accurate, rapid, noninvasive,
repeatable, portable, and involves no nephrotoxic contrast material
or radiation exposure to the patient. There is limited risk for
patients who are pregnant, coagulopathic, or have had previous abdominal
surgery. The average time to perform a complete FAST examination
of the thoracic and abdominal cavities is 2.110 to
4.0 minutes.4 In addition, investigators have demonstrated
that a massive hemoperitoneum may be quickly detected with a single
view of Morison’s pouch in 82% to 90% of hypotensive
patients with an abdominal source of bleeding.8,11 One
major advantage of the FAST examination is the ability to also evaluate
for free pericardial and pleural fluid. Disadvantages of US include
the inability to determine the exact etiology of the free intraperitoneal
fluid and the operator-dependent nature of the examination. Other
potential disadvantages of the FAST examination are the difficulty
in interpreting the images in patients who are obese or have subcutaneous
air or excessive bowel gas, and the inability to distinguish intraperitoneal
hemorrhage from ascites.12 The FAST examination
also cannot evaluate the retroperitoneum as well as CT.
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At Level 1 trauma centers, the ...