Name: focused assessment with sonography for trauma (fast) exam: image acquisition
Uploaded: 2023-09-22T14:05:00.000+00:00
Duration: 7 min 18 s
Description: Watch this Scientific Journal Video about Focused Assessment with Sonography for Trauma FAST Exam: Image Acquisition at JoVE.com

The authors wish to acknowledge Dr. Annie Y. Chen and Ms. Linda Salas Mesa for their assistance with photography.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The patients provided written informed consent for participating in the study. Patient inclusion criteria: any patient with hemodynamic instability or abdominal pain/distension. Patient exclusion criteria: patient refusal.
1. Transducer selection
<ol>
	<li>Select a low-frequency linear transducer (1-5 MHz) (see Table of Materials) to visualize organs deeper than 6 cm in the body1,19.</li>
	<li>If available, select the curvilinear low-frequency probe as its wide footprint maximizes spatial resolution of intra-abdominal organs.</li>
	<li>If the curvilinear probe is not available, select any low-frequency probe such as a sector array probe (aka &#34;phased array probe&#34;, see Table of Materials). 
	NOTE: The sector array probe is sometimes colloquially called the &#34;phased array probe&#34;. However, this latter colloquial term is misleading because all modern ultrasound transducers (including even linear high-frequency transducers) use electronic phasing to steer the ultrasound beam20,21,22, so what distinguishes the sector array from other ultrasound probes is not that it is a &#34;phased array&#34; (all modern transducers are) but that this probe traces out a sector arc. But because many point-of-care ultrasound providers use the term &#34;phased array&#34; to refer to the sector array probe, this manuscript will mention both terms. However, to those interested in the mechanics of how ultrasound machines work, sector array probe is the technically accurate name and is already widely used by ultrasound experts outside of the point-of-care ultrasound world18,23,24,25,26.</li>
	<li>If the e-FAST exam is being performed and is being used to screen for pneumothorax, use a linear high-frequency probe (&#8805; 5 MHz, see Table of Materials) for that application and then resume using a low-frequency probe for the remainder of the FAST/e-FAST exam.</li>
</ol>
2. Machine settings and machine placement
<ol>
	<li>Mode
	<ol>
		<li>Select abdominal mode, which will place the indicator on the left screen and maximize spatial resolution while minimizing temporal resolution. 
		NOTE: In contrast to &#34;abdominal&#34; mode, &#34;cardiac&#34; mode will maximize temporal resolution at the expense of spatial resolution, settings that are optimal for visualizing the fast-moving structures within the heart but unhelpful for visualizing the slow-moving structures in the abdomen or screening for gross fluid in the pericardial sac.</li>
	</ol>
	</li>
	<li>Machine placement
	<ol>
		<li>Place the ultrasound machine on either the patient&#39;s left or right side but ensure that the sonographer has a direct line of sight to both the machine&#39;s screen and to the patient simultaneously so that the operator can manipulate both the ultrasound probe and the ultrasound machine settings concurrently.</li>
	</ol>
	</li>
	<li>Image acquisition preset
	<ol>
		<li>Set the ultrasound machine&#39;s image acquisition technique to prospective collection. If the operator prefers &#34;retrospective collection, &#34; they will need to reverse the order of any paired steps involving fanning the ultrasound probe and click Acquire before image acquisition.</li>
	</ol>
	</li>
</ol>
3. Patient positioning
<ol>
	<li>Position the patient supine with the chest and abdomen exposed1.</li>
	<li>For Right Upper Quadrant (RUQ) and Left Upper Quadrant (LUQ) views, abduct the patient&#39;s arms at least 5 inches away from their body to allow access for the ultrasound probe to reach the patient&#39;s flanks.</li>
</ol>
4. Scanning technique
<ol>
	<li>Apply gel to the ultrasound probe prior to attempting each view.</li>
	<li>Point indicator mark cranially for coronal or sagittal views and toward the patient&#39;s right side for transverse views.</li>
</ol>
5. FAST exam cardiac views
<ol>
	<li>Subxiphoid (aka subcostal) 4-chamber view
	<ol>
		<li>Place the probe on the anterior abdominal wall just caudal to the xiphoid process in the midline or slightly to the patient&#39;s right1.</li>
		<li>Orient the ultrasound beam transversely with the indicator to the patient&#39;s right and the probe nearly flat against the patient&#39;s abdomen and directed towards the patient&#39;s left shoulder1 (Figure 1).</li>
		<li>Adjust probe positioning and screen depth to obtain a view of the four cardiac chambers visualized in the center of the ultrasound image (Figure 2; Video 1).</li>
		<li>Adjust the gain until the intracardiac blood appears uniformly black (anechoic) with just a few specks of grey27.</li>
		<li>Click on Acquire.</li>
		<li>Inspect the circumference of the heart for a similar dark hypoechoic stripe around the myocardium (Figure 2; Video 2).</li>
	</ol>
	</li>
	<li>Parasternal long-axis view (optional) 
	NOTE: In some patients, the subxiphoid window may provide ambiguous findings or inadequate visualization of the pericardium due to abdominal obesity or distended/gas-filled stomach1. In these circumstances, the parasternal window may provide an alternative window to screen for pericardial effusion.
	<ol>
		<li>Place the probe along the left sternal border just caudal to the clavicle with the indicator mark pointing toward the patient&#39;s left hip (Figure 3). 
		NOTE: The transducer indicator mark is pointed toward the patient&#39;s left hip and not toward the right shoulder, as would be done when performing transthoracic cardiac ultrasound because the entire FAST exam is traditionally performed in &#34;abdominal&#34; rather than &#34;cardiac&#34; mode.</li>
		<li>While keeping the probe indicator pointed toward the patient&#39;s left hip, slide (translate) the probe caudally examining each rib interspace until the heart disappears and making a note of which interspaces provided a useful view of the heart.</li>
		<li>Slide (translate) the probe back cranially to the interspace or spaces that provide the best visualization of the heart.</li>
		<li>Adjust probe positioning to obtain a view with the following structures visible: descending thoracic aorta, left atrium, left ventricle, left ventricular outlow tract, right ventricle, and pericardium (Figure 4; Video 3).</li>
		<li>Adjust screen depth so that at least 3-6 cm of depth is visible deep to the descending thoracic aorta (Figure 4; Video 3; Video 4).</li>
		<li>Adjust gain as mentioned in step 5.1.4.</li>
		<li>Click on Acquire.</li>
		<li>Inspect the circumference of the heart for a dark hypoechoic stripe that dissects into the plane between the heart and the descending thoracic aorta (Figure 4).</li>
	</ol>
	</li>
</ol>
6. FAST exam abdominal windows
<ol>
	<li>Right upper quadrant (RUQ) window
	<ol>
		<li>Place the ultrasound probe in the coronal plane on the patient&#39;s right side along the mid-to-posterior axillary line in the 7th to 9th intracoastal space with the probe indicator towards the patient&#39;s head (Figure 5)1,28.</li>
		<li>Adjust the probe positioning to obtain a view containing the following structures: (1) liver; (2) right kidney; (3) hepato-renal interface (a potential space also called Morison&#39;s pouch) (Figure 6; Video 5)1.</li>
		<li>Adjust screen depth so that the hepato-renal interface occupies the middle third of the screen (Figure 6; Video 5).</li>
		<li>Adjust the gain until the liver and kidney appear slightly hyperechoic (tissue echogenicity) but not so dark as completely black and not so bright that they are indistinguishable from their hyperechoic capsules (Figure 6; Video 5). Click on Acquire.</li>
		<li>Fan through the hepato-renal interface anteriorly to posteriorly and back during the video acquisition (Video 6).</li>
		<li>Inspect the hepato-renal recess for a hypoechoic or anechoic stripe between the caudal-most tip of the liver and the inferior pole of the kidney, as this is the most sensitive site for detection of free peritoneal fluid in both the RUQ and usually the entire FAST exam in a supine patient29 (Figure 6; Video 7).</li>
		<li>If the initial view is negative, continue the search for fluid by sliding (translating) the probe caudally into the paracolic gutter and/or cranially to view the hepato-diaphragmatic space between the liver and the diaphragm28,29 (Video 8).
		<ol>
			<li>From the cranial-most RUQ view, visualize the right pleural space cranial to the diaphragm allowing the operator to easily perform this component of the e-FAST exam as a logical extension of the conventional FAST exam1,28,29 (Video 9).</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Left upper quadrant (LUQ) window
	<ol>
		<li>Place the ultrasound probe in the coronal plane on the patient&#39;s left flank along the mid-to-posterior axillary line in the 5th to 7th intracoastal space with the probe indicator towards the patient&#39;s head1,28(Figure 7).</li>
		<li>Adjust the probe positioning to obtain a view containing the following structures: (1) spleen; (2) diaphragm; and (3) if possible, the spleno-renal interface (Figure 8; Video 10).</li>
		<li>Adjust screen depth so that the spleno-diaphragmatic interface occupies the middle third of the screen (Figure 8; Video 10).</li>
		<li>Adjust gain as indicated in step 6.1.4, but replace liver with spleen in the instructions (Figure 8; Video 10). Click on Acquire.</li>
		<li>Fan through the interface between the spleen and diaphragm anteriorly to posteriorly and back during the video acquisition (Video 11).</li>
		<li>Inspect the interface for a hypoechoic or anechoic stripe between the spleen and diaphragm and between the spleen and left kidney (Figure 8; Video 12).</li>
		<li>If the spleno-renal interface was inadequately visualized in steps 6.2.5-6.2.7, slide (translate) the probe caudally until the spleno-renal interface is visualized and repeat steps 6.2.5-6.2.7 but this time focusing on the spleno-renal rather than the spleno-diaphragmatic interface (Video 13).</li>
		<li>To examine the left pleural space (i.e., if performing an e-FAST exam), slide (translate) the probe cranially until the view is centered on the diaphragm1,28 (Video 14).</li>
	</ol>
	</li>
	<li>Suprapubic (pelvic) window 
	NOTE: Since a fluid-filled bladder provides an excellent medium for the transmission of ultrasound waves, imaging the pelvis before insertion of a foley catheter or clamping the foley catheter to allow filling of the bladder can improve image acquisition1,28.
	<ol>
		<li>Transverse suprapubic (pelvic) view
		<ol>
			<li>Position the ultrasound probe in the transverse plane with the indicator mark pointing to the patient&#39;s right side, place the probe just cranial to the pubic symphysis, and angle the ultrasound beam 10-20 degrees caudally into the pelvis1,28 (Figure 9).</li>
			<li>Adjust the probe positioning to obtain a view containing the following sex-specific structures.</li>
			<li>If the patient is female:
			<ol>
				<li>Adjust the probe to visualize the following structures: (1) the bladder in its maximal dimension; (2) the uterus (if present); and (3) the space just posterior to the uterus (rectouterine pouch of Douglas)2&#160;(Figure 10).</li>
				<li>Adjust screen depth so that the uterus occupies the middle third of the screen (Figure 10; Video 15).</li>
				<li>Adjust screen gain so that the urine in the bladder appears relatively anechoic (black) and the space deep into the bladder is distinct from the posterior bladder wall (Figure 10; Video 15).</li>
			</ol>
			</li>
			<li>If the patient is male:
			<ol>
				<li>Adjust the probe to visualize the following structures: (1) the bladder in its maximal dimension and (2) the space just posterior to the bladder (recto-vesical pouch)2 (Figure 11; Video 16).</li>
				<li>Adjust screen depth so that the bladder occupies the middle third of the screen (Figure 11; Video 16).</li>
				<li>Adjust the screen gain so that the urine in the bladder appears relatively anechoic (black) and the space deep into the bladder is distinct from the posterior bladder wall (Figure 11; Video 16).</li>
			</ol>
			</li>
			<li>Click on Acquire. Fan across the pelvis posteriorly to anteriorly during the video acquisition (Video 17).</li>
			<li>Inspect the view for an anechoic stripe in the peri-uterine/rectouterine space if the patient is female (Figure 10B; Video 18) and in the recto-vesical space if the patient is male (Figure 11B; Video 19).</li>
		</ol>
		</li>
		<li>Sagittal suprapubic (pelvic) view
		<ol>
			<li>Starting with the transverse view above (6.3.1.1), rotate the ultrasound probe 90 degrees clockwise until the ultrasound beam is in the sagittal plane with the indicator mark pointing to the patient&#39;s head and keep the ultrasound beam angled 10-20 degrees caudally into the pelvis1,28&#160;(Figure 12).</li>
			<li>Adjust the probe positioning to obtain a view containing the following sex-specific structures.</li>
			<li>If the patient is female:
			<ol>
				<li>Adjust the probe to visualize the following structures: (1) the bladder in its maximal dimension; (2) the uterus (if present); and (3) the space just posterior to the uterus (rectouterine pouch of Douglas)2&#160;(Figure 13; Video 20).</li>
				<li>Adjust screen depth so that the uterus occupies the middle third of the screen (Figure 13; Video 20).</li>
				<li>Adjust screen gain so that the urine in the bladder appears relatively anechoic (black) and the space deep to the bladder is distinct from the posterior bladder wall (Figure 13; Video 20).</li>
			</ol>
			</li>
			<li>If the patient is male:
			<ol>
				<li>Adjust the probe to visualize the following structures: (1) the bladder in its maximal dimension and (2) the space just posterior to the bladder (recto-vesical pouch)2&#160;(Figure 14; Video 21).</li>
				<li>Adjust screen depth so that the bladder occupies the middle third of the screen (Figure 14; Video 21).</li>
				<li>Adjust the screen gain so that the urine in the bladder appears relatively anechoic (black) and the space deep into the bladder is distinct from the posterior bladder wall (Figure 14; Video 21).</li>
			</ol>
			</li>
			<li>Click on Acquire. Fan across the pelvis left-to-right and back during the video acquisition (Video 22).</li>
			<li>Inspect the view for an anechoic stripe in the peri-uterine/rectouterine space if the patient is female (Video 23) and in the recto-vesical space if the patient is male (Video 24).</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

YB is an Editor on the American Society of Anesthesiologists' Editorial Board on Point-of-Care Ultrasound and Section Editor for POCUS for OpenAnesthesia.org.

Traumatic injuries remain a leading cause of morbidity and mortality in the United States and worldwide. The rapid evaluation of the trauma patient and identification of injuries, including major hemorrhage, is a key component of reducing trauma morbidity. The FAST exam rapidly and non-invasively screens for potential sources of life-threatening hemorrhage. Critical steps to the success of the procedure are obtaining all of the views through the four primary ultrasonographic windows and, if necessary, using the alternative parasternal window to fully visualize the spaces.
The key to the successful use of the FAST exam in trauma remains the identification and interpretation of free fluid in the pericardium, peritoneal, and - if possible - pleural spaces1. Both false positive and false negative exams are possible. False negative exams may occur for a variety of reasons but generally are due to an inability to obtain adequate visualization of the target anatomy or insufficient free fluid for detection39,40,41. The inability to obtain images is related to patient factors such as obesity, subcutaneous air, movement, and injuries which preclude appropriate windows39,41,42. False positive exams are typically related to the misinterpretation of anatomic information. In the pericardial space, the epicardial fat pad may appear hypo-echoic in relation to the myocardium and may be misinterpreted as a positive pericardial window34. Similar fluid-filled normal anatomic structures such as gallbladder and bowel and pathology such as hepatic or renal cysts or ascites may be misinterpreted as free peritoneal fluid39,42. Because of the potential to encounter all these false positives for pericardial fluid in the SC4C view, other authors and we recommend obtaining the PLAX view to determine whether peri-cardiac fluid seen in the SC4C view is truly located in the pericardial sac or not (see Representative Results section)34.
In addition to false negative and positive exams, true positive and negative exams which correctly identify the presence or absence of free fluid may misinterpret the clinical significance of these findings1,39,40,41,42. Though in the setting of trauma, free pericardial or peritoneal fluid is presumed to represent the blood, in the setting of hemodynamic instability, it may, in fact, represent other physiologic or pathologic conditions39,43. Ascites is the prototypical example of the medical condition leading to a true positive FAST exam with indeterminate significance in the trauma evaluation. Finally, a true negative FAST exam, which correctly identifies no significant peritoneal fluid, does not rule out injuries requiring exploratory laparotomy1,39. Hollow viscus injuries, which require surgical repair, as well as retroperitoneal organ injuries and hemorrhage are not adequately identified.
Given the many potential pitfalls, when used for the primary indication of blunt thoracoabdominal trauma, the FAST exam demonstrates good specificity and sensitivity. In a recent Cochrane review, overall sensitivity was estimated at 74%, and specificity was 96%44. However, in a pediatric population, both sensitivity and specificity were lower at 63% and 91%, respectively. Similarly, there was a marked decreased sensitivity of 28%-100% with preserved specificity (94%-100%) when studies looking at penetrating abdominal trauma were reviewed. Outside of the trauma setting, the abdominal portion of the exam can be used to screen for free peritoneal fluid for any patient where such fluid could contribute to a patient&#39;s symptoms of hemodynamic instability and/or abdominal pain/distension. Thus, the abdominal portion of the FAST exam is sometimes relevant to the care of non-trauma patients, as any patient can develop clinically significant amounts of intra-abdominal fluid for a variety of reasons (e.g., peri-procedural abdominal organ injury, bladder rupture, uterine rupture, ascites accumulation, etc.). However, the sensitivity and specificity of the FAST exam in these non-trauma settings have not been rigorously studied. Therefore the primary indication for the FAST exam remains the evaluation of hemodynamically unstable blunt thoraco-abdominal trauma patients for whom rapid clinical decision-making is necessary and who cannot safely undergo a CT scan. Outside of the trauma setting, other applications include any of the following: triaging the severity of obstetric hemorrhage10, screening for a cause of abdominal pain/distension, and as part of the preoperative assessment of patients with suspected but unconfirmed ascites scheduled for elective surgery11,12,13.
As the technology of portable ultrasonography improves and provider familiarity and comfort with ultrasonographic image acquisition increases, further applications in intensive care and even prehospital setting are inevitable.

The Focused Assessment with Sonography for Trauma (FAST) exam is a diagnostic point-of-care ultrasound (POCUS) exam of the torso designed to rapidly assess potentially life-threatening hemorrhage in trauma patients1. The FAST exam was one of the earliest POCUS techniques to achieve widespread adoption: it was first developed in the 1980s in Europe and spread to the United States in the early 1990s. As POCUS became more commonly utilized in the evaluation of trauma patients, a consensus conference was held in 1997, which standardized the definition of the FAST exam and its role in the care of trauma patients. Over time, some authors have advocated for adding a focused ultrasound exam of the lung to the traditional FAST exam and have termed this multi-organ exam the extended FAST (e-FAST) exam2.
The primary role of both the classical FAST and its newer iteration, e-FAST, is in the initial evaluation of trauma patients3. Hemodynamic instability in traumatically injured patients is commonly caused by a limited number of conditions, including primary hemorrhage, cardiac tamponade, and tension pneumothorax3,4. As a part of the ACBDE steps of the Advanced Trauma Life Support(ATLS) primary survey, the Circulation step looks to identify and treat the life-threatening causes of hemodynamic instability in trauma patients3,5,6. This step includes ruling out cardiac tamponade and intracavitary bleeding in the pleural spaces and peritoneum, among other sources6,7. The FAST exam allows for visualization of free fluid in the pericardium and peritoneum, and with e-FAST views, bilateral pleural spaces3,6,7. In the clinical picture of hemodynamic instability after major trauma, this fluid is presumed to be blood until proven otherwise.
As a point-of-care ultrasound examination, the FAST/e-FAST exam offers several advantages. The exam can be performed using small portable ultrasound machines at the patient&#39;s bedside while other care is ongoing and without requiring the transport of the patient 3. The limited views using B-mode technique means that a complete examination can be obtained rapidly within a few minutes, and the noninvasive nature of the ultrasound exam means that the exam can be easily repeated if the patient&#39;s clinical picture changes3,8,9.
At the same time, the simple nature of the FAST exam has several limitations. Like any ultrasound examination, it is operator dependent to obtain appropriate views and accurate interpretation of the images in real-time9. Various patient factors, including obesity, and subcutaneous emphysema, may limit the ability to acquire adequate images. Additionally, the simplified views of the FAST/e-FAST exams do not look for specific organ injuries but rather screen for free fluid in the various body compartments. In the appropriately selected trauma patient, this free fluid is likely to represent blood from ongoing hemorrhage but may represent other fluid from traumatic or non-traumatic medical conditions.
Given the advantages and limitations of the FAST/e-FAST exams, their primary indication is in evaluating hemodynamically unstable patients who have suffered blunt trauma. For this patient population, the primary goal is to identify traumatic sources of hemodynamic instability, such as cardiac tamponade and intracavitary hemorrhage, which require immediate operative intervention. In this role, it has replaced diagnostic peritoneal lavage (DPL) as the primary modality for diagnosing intraperitoneal hemorrhage and physical examination and challenges the chest X-ray for diagnosing intrapleural hemorrhage and pneumothorax1. With their rapid and noninvasive nature, the FAST/e-FAST exams have been used in other trauma patients, including hemodynamically stable blunt trauma patients and penetrating trauma patients, both stable and unstable. However, the indications for and interpretation of these exams remain less clear.
Outside of the trauma setting, the FAST exam may have value in several different crisis management situations, including but not limited to any of the following: triaging the severity of obstetric hemorrhage10, searching for the location of perioperative bleeding, screening for peri-procedural bladder rupture, and as part of the preoperative assessment of patients with suspected but unconfirmed ascites scheduled for elective surgery11,12,13. In these non-trauma contexts, the providers available to perform the FAST exam are likely to come from specialties like obstetrics, anesthesiology, internal medicine, and critical care, for whom FAST exam training is highly variable in residency/fellowship curricula13,14,15,16. It is these non-trauma specialties that form the target audience of this review. Some of these non-trauma specialties tend to either have existing expertise in lung ultrasound (e.g., intensivists17) or have reasons to perform the abdominal views of the FAST exam in isolation (e.g., anesthesiologists and obstetricians)10. For these reasons and because the lung views of the e-FAST exam are already comprehensively covered in a separate manuscript18, this review will focus primarily on image acquisition for the abdominal views of the FAST exam. Despite this, it is worth emphasizing that, in the trauma setting, sonographic examination of the lung is, in many hospitals, considered a core part of the FAST protocol (i.e., e-FAST is the form of the FAST exam preferred by some trauma providers).

<table><tbody><tr><td>Affiniti&amp;nbsp; (including linear high-frequency, curvilinear, and sector array transducers)</td><td>Philips</td><td>n/a</td><td>Used to obtain a subset of the Figures and Videos</td></tr><tr><td>Edge 1 ultrasound machine (including linear high-frequency, curvilinear, and sector array transducers)</td><td>SonoSite</td><td>n/a</td><td>Used to obtain a subset of the Figures and Videos</td></tr><tr><td>M9 (including linear high-frequency, curvilinear, and sector array transducers)</td><td>Mindray</td><td>n/a</td><td>Used to obtain a subset of the Figures and Videos</td></tr><tr><td>Vivid iq&amp;nbsp; (including linear high-frequency, curvilinear, and sector array transducers)</td><td>GE</td><td>n/a</td><td>Used to obtain a subset of the Figures and Videos</td></tr></tbody></table>

focused assessment with sonography for trauma (fast) exam: image acquisition

Over the past twenty years, the Focused Assessment with Sonography for Trauma (FAST) exam has transformed the care of patients presenting with a combination of trauma (blunt or penetrating) and hypotension. In these hemodynamically unstable trauma patients, the FAST exam permits rapid and noninvasive screening for free pericardial or peritoneal fluid, the latter of which implicates intra-abdominal injury as a likely contributor to the hypotension and justifies emergent abdominal surgical exploration. Further, the abdominal portion of the FAST exam can also be used outside of the trauma setting to screen for free peritoneal fluid in patients who become hemodynamically unstable in any context, including after procedures that may inadvertently injure abdominal organs. These "non-trauma" situations of hemodynamic instability are often triaged by providers from specialties other than emergency medicine or trauma surgery who are not familiar with the FAST exam. Therefore, there is a need to promulgate knowledge about the FAST exam to all clinicians caring for critically ill patients. Toward this end, this article describes FAST exam image acquisition: patient positioning, transducer selection, image optimization, and exam limitations. Since the free fluid is likely to be found in specific anatomic locations that are unique for each canonical FAST exam view, this work centers on the unique image acquisition considerations for each window: subcostal, right upper quadrant, left upper quadrant, and pelvis.

Watch this Scientific Journal Video about Focused Assessment with Sonography for Trauma FAST Exam: Image Acquisition at JoVE.com

Focused Assessment with Sonography for Trauma FAST Exam: Image Acquisition

The Focused Assessment with Sonography for Trauma (FAST) exam is a diagnostic point-of-care ultrasound examination used to screen for the presence of free fluid in the pericardium and peritoneum. Indications, techniques, and pitfalls of the procedure are discussed in this article.

Focused Assessment with Sonography for Trauma (FAST) Exam: Image Acquisition

Over the past twenty years, the Focused Assessment with Sonography for Trauma (FAST) exam has transformed the care of patients presenting with a ...

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An Overview of the Gastrointestinal System: Anatomy, Physiology, and Assessment

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5.7K Views.  Duke University Hospital. Het FAST-examen is ontworpen om te screenen op verschillende soorten levensbedreigende pathologie die het meest relevant zijn voor de zorg voor traumapatiënten. Hemopericardium, pneumothorax, hemothorax en vrij peritoneaal vocht. Dit FAST-protocol legt de nadruk op een aantal sleutelbegrippen die, naar onze ervaring, ondergewaardeerd worden.Ten eerste, het nut van de parasternale lange as-weergave als een toevoeging. Twee, het patroon van vrije peritoneale vloeistof in het kwadrant li...

Video: Focused Assessment with Sonography for Trauma FAST Exam: Image Acquisition

A High-performance Compact Photoacoustic Tomography System for In Vivo Small-animal Brain Imaging

In vivo small-animal imaging has an important role to play in preclinical studies. Photoacoustic tomography (PAT) is an emerging hybrid imaging modality that shows great potential for both preclinical and clinical applications. Conventional optical parametric oscillator-based PAT (OPO-PAT) systems are bulky and expensive and cannot provide high-speed imaging. Recently, pulsed-laser diodes (PLDs) have been successfully demonstrated as an alternative excitation source for PAT. Pulsed-laser diode PAT (PLD-PAT) has been successfully demonstrated for high-speed imaging on photoacoustic phantoms and biological tissues. This work provides a visualized experimental protocol for in vivo brain imaging using PLD-PAT. The protocol includes the compact PLD-PAT system configuration and its description, animal preparation for brain imaging, and a typical experimental procedure for 2D cross-sectional rat brain imaging. The PLD-PAT system is compact and cost-effective and can provide high-speed, high-quality imaging. Brain images collected in vivo at various scan speeds are presented.

A High-performance Compact Photoacoustic Tomography System for In Vivo Small-animal Brain Imaging

A compact pulsed-laser diode-based photoacoustic tomography (PLD-PAT) system for high-speed in vivo brain imaging in small animals is demonstrated.

In vivo small-animal imaging has an important role to play in preclinical studies. Photoacoustic tomography (PAT) is an emerging hybrid imaging modality ...

Bioengineering

Blood Flow Imaging with Ultrafast Doppler

The pulsed-Doppler effect is the main technique used in clinical echography to assess blood flow. Applied with conventional focused ultrasound Doppler modes, it has several limits. Firstly, a finely tuned signal filtering operation is needed to distinguish blood flows from surrounding moving tissues. Secondly, the operator must choose between localizing the blood flows or quantifying them. In the last two decades, ultrasound imaging has undergone a paradigm shift with the emergence of ultrafast ultrasound using unfocused waves. In addition to a hundredfold increase in framerate (up to 10000 Hz), this new technique also breaks the conventional quantification/localization trade-off, offering a complete blood flow mapping of the field of view and a simultaneous access to fine velocities measurements at the single-pixel level (down to 50 &#181;m). This data continuity in both spatial and temporal dimensions strongly improves the tissue/blood filtering process, which results in an increase sensitivity to small blood flow velocities (down to 1 mm/s). In this method paper, we aim to introduce the concept of ultrafast Doppler as well as its main parameters. Firstly, we summarize the physical principles of unfocused wave imaging. Then, we present the Doppler signal processing main steps. Particularly, we explain the practical implementation of the critical tissue/blood flow separation algorithms and on the extraction of velocities from these filtered data. This theoretical description is supplemented by in vitro experiences. A tissue phantom embedding a canal with flowing blood-mimicking fluid is imaged with a research programmable ultrasound system. A blood flow image is obtained and the flow characteristics are displayed for several pixels in the canal. Finally, a review of in vivo applications is proposed, showing examples in several organs such as carotids, kidney, thyroid, brain and heart.

This protocol shows how to apply ultrafast ultrasound Doppler imaging to quantify blood flows. After a 1 s long acquisition, the experimenter has access to a movie of the full field of view with axial velocity values for each pixel every &#8776;0.3 ms (depending on the ultrasound time of flight).

The pulsed-Doppler effect is the main technique used in clinical echography to assess blood flow. Applied with conventional focused ultrasound Doppler ...

Observational Study Protocol for Repeated Clinical Examination and Critical Care Ultrasonography Within the Simple Intensive Care Studies

Longitudinal evaluations of critically ill patients by combinations of clinical examination, biochemical analysis and critical care ultrasonography (CCUS) may detect adverse events of interventions such as fluid overload at an early stage. The Simple Intensive Care Studies (SICS) is a research line that focuses on the prognostic and diagnostic value of combinations of clinical variables.
The SICS-I specifically focused on the use of clinical variables obtained within 24 h of acute admission for prediction of cardiac output (CO) and mortality. Its sequel, SICS-II, focuses on repeated evaluations during ICU admission. The first clinical examination by trained researchers is performed within 3 h after admission consisting of physical examination and educated guessing. The second clinical examination is performed within 24 h after admission and includes physical examination and educated guessing, biochemical analysis and CCUS assessments of heart, lungs, inferior vena cava (IVC) and kidney. This evaluation is repeated at days 3 and 5 after admission. CCUS images are validated by an independent expert, and all data is registered in an online secured database. Follow-up at 90 days includes registration of complications and survival status according to patient&#39;s medical charts and the municipal person registry. The primary focus of SICS-II is the association between venous congestion and organ dysfunction.
The purpose of publishing this protocol is to provide details on the structure and methods of this on-going prospective observational cohort study allowing answering multiple research questions. The design of the data collection of combined clinical examination and CCUS assessments in critically ill patients are explicated. The SICS-II is open for other centers to participate and is open for other research questions that can be answered with our data.

Structured protocols are necessary to provide answers on research questions in critically ill patients. The Simple Intensive Care Studies (SICS) provides an infrastructure for repeated measurements in critically ill patients including clinical examination, biochemical analysis and ultrasonography. SICS projects have specific focus but the structure is flexible to other investigations.

Longitudinal evaluations of critically ill patients by combinations of clinical examination, biochemical analysis and critical care ultrasonography (CCUS) ...

Ultrasonographic Assessment During Cardiopulmonary Resuscitation

The US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol integrates several sonographic techniques into a structured assessment of the circulation, airway, and breathing status of a patient during cardiopulmonary resuscitation (CPR) in an advanced life support-compliant manner. US-C provides a subxiphoid view of the heart, to look for potentially reversible causes of disease, such as pericardial effusion, pulmonary embolism, hypovolemia, and acute coronary thrombosis. Sonographic cardiac activity during CPR not only helps differentiate pseudo-pulseless electrical activity (PEA) from true PEA but also represents a higher chance of the return of spontaneous circulation (ROSC) and survival. Evaluation of the inferior vena cava (IVC) shows the fluid status of the patient and indicates the best methods to use for fluid resuscitation. If aortic dissection is suspected, a subxiphoid view of the aorta is suggested for identifying an intimal flap. Once intubation is done, tracheal ultrasound (US-A) at the suprasternal notch helps differentiate endotracheal intubation (one air-mucosal interface with one comet-tail) from esophageal intubation (double tract sign). Immediately following US-A, bilateral lung US (US-B) should be done to confirm proper bilateral ventilation using the lung sliding sign. In addition, US-C can be serially followed to see the dynamic changes in the cardiac chambers and IVC, or any cardiac contraction suggestive of ROSC. US-B can also detect coexisting lung or pleural pathologies without interfering with the performance of CPR. The main concern when implementing this method is maintaining high-quality CPR without delays in chest compressions when performing US-CAB. Rigorous training and continued practice are key to minimize any interruptions during resuscitation.

Here, we present a US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol for use during cardiopulmonary resuscitation (CPR). US-C evaluates the subxiphoid view of the heart and inferior vena cava. After intubation, tracheal US (US-A) and lung US (US-B) help confirm endotracheal intubation and proper ventilation.

The US-CAB (Ultrasound, Circulation/Airway/Breathing) protocol integrates several sonographic techniques into a structured assessment of the circulation, ...

Non-Invasive Integrated PAUSAT Whole-Brain Imaging of Ischemic Stroke

Integrated Photoacoustic, Ultrasound, and Angiographic Tomography (PAUSAT) for NonInvasive Whole-Brain Imaging of Ischemic Stroke

Presented here is an experimental ischemic stroke study using our newly developed noninvasive imaging system that integrates three acoustic-based imaging technologies: photoacoustic, ultrasound, and angiographic tomography (PAUSAT). Combining these three modalities helps acquire multi-spectral photoacoustic tomography (PAT) of the brain blood oxygenation, high-frequency ultrasound imaging of the brain tissue, and acoustic angiography of the cerebral blood perfusion. The multi-modal imaging platform allows the study of cerebral perfusion and oxygenation changes in the whole mouse brain after stroke. Two commonly used ischemic stroke models were evaluated: the permanent middle cerebral artery occlusion (pMCAO) model and the photothrombotic (PT) model. PAUSAT was used to image the same mouse brains before and after a stroke and quantitatively analyze both stroke models. This imaging system was able to clearly show the brain vascular changes after ischemic stroke, including significantly reduced blood perfusion and oxygenation in the stroke infarct region (ipsilateral) compared to the uninjured tissue (contralateral). The results were confirmed by both laser speckle contrast imaging and triphenyltetrazolium chloride (TTC) staining. Furthermore, stroke infarct volume in both stroke models was measured and validated by TTC staining as the ground truth. Through this study, we have demonstrated that PAUSAT can be a powerful tool in noninvasive and longitudinal preclinical studies of ischemic stroke.

Author Spotlight: Integrated Photoacoustic, Ultrasound, and Angiographic Tomography (PAUSAT) for NonInvasive Whole-Brain Imaging of Ischemic Stroke  

This work demonstrates the use of a multimodal ultrasound-based imaging platform for noninvasive imaging of ischemic stroke. This system allows for the quantification of blood oxygenation through photoacoustic imaging and impaired perfusion in the brain through acoustic angiography.

Presented here is an experimental ischemic stroke study using our newly developed noninvasive imaging system that integrates three acoustic-based imaging ...

Neuroscience

Image Acquisition using Portable Sonography for Emergency Airway Management

With its increasing popularity and accessibility, portable ultrasonography has been rapidly adapted not only to improve the perioperative care of patients, but also to address the potential benefits of employing ultrasound in airway management. The benefits of point of care ultrasound (POCUS) include its portability, the speed at which it can be utilized, and its lack of invasiveness or exposure of the patient to radiation of other imaging modalities.
Two primary indications for airway POCUS include confirmation of endotracheal intubation and identification of the cricothyroid membrane in the event a surgical airway is required. In this article, the technique of using ultrasound to confirm endotracheal intubation and the relevant anatomy is described, along with the associated ultrasonographic images. In addition, identification of the anatomy of the cricothyroid membrane and the ultrasonographic acquisition of appropriate images to perform this procedure are reviewed.
Future advances include utilizing airway POCUS to identify patient characteristics that might indicate difficult airway management. Traditional bedside clinical exams have, at best, fair predictive values. The addition of ultrasonographic airway assessment has the potential to improve this predictive accuracy. This article describes the use of POCUS for airway management, and initial evidence suggests that this has improved the diagnostic accuracy of predicting a difficult airway. Given that one of the limitations of airway POCUS is that it requires a skilled sonographer, and image analysis can be operator dependent, this paper will provide recommendations to standardize the technical aspects of airway ultrasonography and promote further research utilizing sonography in airway management. The goal of this protocol is to educate researchers and medical health professionals and to advance the research in the field of airway POCUS.

Point of care ultrasound (POCUS) is increasingly being utilized in airway management. Presented here are some clinical utilities of POCUS, including differentiating endotracheal and esophageal intubation, identification of the cricothyroid membrane in the event a surgical airway is required, and measuring anterior neck soft tissue to predict difficult airway management.

With its increasing popularity and accessibility, portable ultrasonography has been rapidly adapted not only to improve the perioperative care of ...

Image Acquisition Method for the Sonographic Assessment of the Inferior Vena Cava

Over the past several decades, clinicians have incorporated several applications of diagnostic point-of-care ultrasound (POCUS) into medical decision-making. Among the applications of POCUS, imaging the inferior vena cava (IVC) is practiced by a wide variety of specialties, such as nephrology, emergency medicine, internal medicine, critical care, anesthesiology, pulmonology, and cardiology. Although each specialty uses IVC data in slightly different ways, most medical specialties, at minimum, attempt to use IVC data to make predictions about intravascular volume status. While the relationship between IVC sonographic data and intravascular volume status is complex and highly context-dependent, all clinicians should collect the sonographic data in standardized ways to ensure repeatability. This paper describes standardized IVC image acquisition including patient positioning, transducer selection, probe placement, image optimization, and the pitfalls and limitations of IVC sonographic imaging.&#160;This paper also describes the commonly performed anterior IVC long-axis view and three other views of the IVC that can each provide helpful diagnostic information when the anterior long-axis view is difficult to obtain or interpret.

Point-of-care ultrasound evaluation of the inferior vena cava (IVC) is commonly utilized to identify, among other things, the volume status. Imaging should be performed systematically to ensure repeatability. This manuscript reviews the methods and pitfalls of sonographic IVC examination.

Over the past several decades, clinicians have incorporated several applications of diagnostic point-of-care ultrasound (POCUS) into medical ...

Troubleshooting FoCUS Image Acquisition: Patient Positioning, Transducer Manipulation, and Image Optimization

Focused cardiac ultrasound (FoCUS) is a limited, clinician-performed application of echocardiography to add real-time information to patient care. These bedside exams are problem oriented, rapidly and repeatedly performed, and largely qualitative in nature. Competency in FoCUS includes mastery of the stereotactic and psychomotor skills required for transducer manipulation and image acquisition. Competency also requires the ability to optimize the setup, troubleshoot image acquisition, and understand the sonographic limitations because of complex clinical environments and patient pathology. This article presents concepts for successful, high-quality two-dimensional (B-mode) image acquisition in FoCUS.
Concepts of high-quality image acquisition can be applied to all established sonographic windows of the FoCUS exam: the parasternal long-axis (PLAX), parasternal short-axis (PSAX), apical four chamber (A4C), subcostal fourchamber (SC4C), and the inferior vena cava (IVC). The apical five-chamber (A5C) and subcostal short-axis (SCSA) views are mentioned, but are not discussed in-depth. A pragmatic figure illustrating the movements of the phased array transducer is also provided to serve as a cognitive aid during FoCUS image acquisition.

Here, we present a protocol to allow providers to perform focused cardiac ultrasound (FoCUS) in the clinical environment. We describe methods of transducer manipulation, review common pitfalls of transducer movements, and suggest tips to optimize phased array transducer use.

Focused cardiac ultrasound (FoCUS) is a limited, clinician-performed application of echocardiography to add real-time information to patient care. These ...

A Modified Sonographic Algorithm for Image Acquisition in Life-Threatening Emergencies in the Critically Ill Newborn

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h equipment availability. In 2018, the sonographic algorithm for life-threatening emergencies (SAFE) protocol was published, which allows the assessment of neonates with sudden decompensation to identify abnormal contractility, tamponade, pneumothorax, and pleural effusion. In the study unit (with a consulting neonatal hemodynamics and POCUS service), the algorithm was adapted by including consolidated core steps to support at-risk newborns, aiding clinicians in managing cardiac arrest, and adding views to verify correct intubation. This paper presents a protocol that can be applied in the NICU and the delivery room (DR) in relation to three scenarios: cardiac arrest, hemodynamic deterioration, or respiratory decompensation. 
This protocol can be performed with a state-of-the-art ultrasound machine or an affordable handheld device; the image acquisition protocol is carefully detailed. This method was designed to be learned as a general competence to obtain the timely diagnosis of life-threatening scenarios; the method aims to save time but does not represent a substitute for comprehensive and standardized hemodynamic and radiological analyses by a multidisciplinary team, which might not universally be on call but needs to be involved in the process. From January 2019 to July 2022, in our center, 1,045 hemodynamic consultation/POCUS consults were performed with 25 patients requiring the modified SAFE protocol (2.3%), and a total of 19 procedures were performed. In five cases, trained fellows on call resolved life-threatening situations. Clinical examples are provided that show the importance of including this technique in the care of critical newborns.

Here, we present a protocol that can be applied in the neonatal intensive care unit and the delivery room in relation to three scenarios: cardiac arrest, hemodynamic deterioration, or respiratory decompensation. This protocol can be performed with a state-of-the-art ultrasound machine or an affordable handheld device; an image acquisition protocol is carefully detailed.

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h ...

Imaging the Abdominal Aorta with Point-of-Care Ultrasound

An Approach to Point-Of-Care Ultrasound Evaluation of the Abdominal Aorta

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography (CT) is the current gold standard to image the abdominal aorta, the process of obtaining a CT may be time-consuming, requires the use of intravenous contrast dye, and involves exposure to ionizing radiation. Point-of-care Ultrasound (POCUS) can be performed at the bedside and has excellent sensitivity and specificity for the diagnosis of abdominal aortic aneurysm and excellent specificity for the diagnosis of abdominal aortic dissection. Additionally, POCUS is non-invasive, cost-effective, lacks ionizing radiation, requires no intravenous contrast dye, and can be performed without taking the patient from a critical care area. Screening for abdominal aortic aneurysm (AAA) can be done in primary care settings as well. 
This article will review the approach to POCUS of the abdominal aorta to evaluate such critical pathology. In this paper, we will review the sonographic anatomy of the abdominal aorta as well as the choice of the ultrasound probe, description of POCUS image acquisition, and some pearls and pitfalls of using POCUS to aid in the diagnosis of potentially life-threatening abdominal aortic pathology.

Author Spotlight: Using Point-of-Care Ultrasound for Comprehensive Evaluation of the Abdominal Aorta

This protocol reviews the steps to image the abdominal aorta with point-of-care ultrasound. We discuss image acquisition, troubleshooting imaging pitfalls and artifacts, and the recognition of life-threatening abdominal aortic pathology.

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography ...

Focused Assessment with Sonography for Trauma (FAST) Exam: Image Acquisition

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