BEFAST (Bubble-Enhanced FAST) for the Evaluation of Solid Organ Injury (BEFAST)

BEFAST (Bubble-Enhanced FAST) for the Evaluation of Solid Organ Injury in Hemodynamically Stable Blunt Abdominal Trauma

The Focused Assessment with Sonography for Trauma (FAST) exam is widely used and accepted as part of advanced trauma life support (ATLS) protocol, but its low sensitivity for identifying solid organ injury in the absence of hemoperitoneum is a significant limitation. Contrast-enhanced ultrasound (CEUS) has the potential to significantly enhance the evaluation of the trauma patient with acute intra-abdominal injury through the use of intravascular microbubbles that allow direct visualization of lacerations to solid organs. European studies have demonstrated that ultrasound contrast markedly improves the sensitivity of ultrasound in detecting solid organ injury, when the exam is performed in the radiology suite. The researchers hypothesize that the bubble-enhanced FAST or BEFAST exam will be more sensitive than traditional FAST for identification of solid organ injury in hemodynamically stable blunt abdominal trauma patients when performed by emergency providers.

Blunt abdominal trauma, whether from motor vehicle crash, assault, fall, or recreational injury, is a leading cause of morbidity and mortality. According to the 2016 National Trauma Database, 12% of all patients with trauma admissions had abdominal trauma, the majority of which is blunt. The diagnosis of intra-abdominal injury due to blunt abdominal trauma can be challenging. The physical exam is unreliable in patients with altered mental status or with impairment due to drugs or alcohol. While computed tomography (CT) can rapidly and accurately diagnose injury, emergency physicians have raised concerns that the use of CT has become overly liberal. The risks of overutilization of CT in hemodynamically stable blunt abdominal trauma include increased health care costs, lengthy stays in the emergency department, risks of contrast-induced nephropathy and radiation-induced malignancy, and patient anxiety when "incidentalomas" are discovered that need extensive and often unnecessary workup. The Focused Assessment with Sonography for Trauma (FAST) exam is widely used and accepted as part of the advanced trauma life support (ATLS) protocol, but its low sensitivity for identifying solid organ injury in the absence of hemoperitoneum is a significant limitation. Contrast-enhanced ultrasound (CEUS) has the potential to significantly enhance the evaluation of the trauma patient with acute intra-abdominal injury through the use of intravascular microbubbles that allow direct visualization of lacerations to solid organs. In 2016, the Food and Drug Administration (FDA) approved Lumason (sulfur hexafluoride lipid-type A microsphere) for characterization of focal liver lesions with CEUS in both adult and pediatric patients, opening new areas of research in the United States. Lumason is a second generation contrast agent that is more stable than previous ultrasound contrast agents and does not require refrigeration. Although approved for intravascular and intravesical use, Lumason's use in a trauma exam is off-label in the United States. After participants provide informed consent, a baseline FAST exam will be performed and documented. This exam will be distinct from the initial ATLS resuscitation FAST in order to avoid any interference in the trauma evaluation. If not already placed, an intravenous line will be established according to standard practice for trauma patients. Following the FAST exam, a bubble-enhanced FAST (BEFAST) exam will be performed using Lumason as the contrast agent. As part of the standard of care, participants will have a CT exam performed within 24 hours, which will provide the gold standard for diagnosis of solid organ trauma.

The interpretation of the point-of-care emergency medicine (EM) physician (blind to the CT read) will be compared to the interpretations of board-certified radiologists (also blind to the CT read) for the presence or absence of solid organ injury.

Participants in the emergency department with hemodynamically stable blunt abdominal trauma will receive the standard of care Focused Assessment with Sonography for Trauma (FAST) exam followed by a Bubble-Enhanced FAST exam.

The Focused Assessment with Sonography for Trauma (FAST) exam is widely used and accepted as part of Advanced Trauma Life Support (ATLS) protocol. After consent, a baseline FAST exam will be performed and documented. This FAST will be distinct from the initial ATLS resuscitation FAST in order to avoid any interference in the trauma evaluation. The investigator will use a phased array or curvilinear transducer to record video of their baseline FAST exam.

Following the FAST exam and using the same machine, a BEFAST exam will be performed using a low mechanical index setting in contrast-specific imaging mode. A 2.4 mL IV dose of Lumason will be injected into the subject's IV, followed by saline flush. The contrast will be injected once for the right side of the body, and once for the left side of the body looking for disruptions in the normal enhancement pattern and evidence of active bleeding. Contrast may be redosed if images are inadequate or incomplete. To examine the right side of the body: the liver will be imaged first in arterial phase, followed by the right kidney, before returning to image the liver in venous phase. To examine the left side of the body: the pancreas will be imaged first, followed by the kidney and the spleen. The investigator will note evidence of solid organ injury, free fluid, or active extravasation on both sides of the body; lacerations will be graded by AAST criteria.

The performance of the study exams will be assessed as the percentage of correctly identified solid organ injuries (true positives) detected by FAST exam and BEFAST exam. The presence of injury will be determined by the gold standard of a CT exam, conducted within 24 hours as part of the standard of care.

The performance of the study exams will be assessed as the percentage of correctly identified lack of solid organ injuries (true negatives) detected by FAST and BEFAST exams. The presence of solid organ injury will be determined by the gold standard of a CT exam, conducted within 24 hours as part of the standard of care.

The number of successful, completed exams will be used to determine whether emergency physicians can incorporate BEFAST evaluation at the point-of-care. The exam is considered complete if the participant tolerates the study without experiencing severe adverse events to contrast and the participant allows the provider to complete the scan, and if the exam results in images of adequate quality to answer the focused clinical question.

Emergency physicians' interpretations of the ultrasound exams will be compared to interpretations of board-certified radiologists for the presence or absence of solid organ injury, free fluid, or active extravasation. Injured organs will be graded per American Association for the Surgery of Trauma (AAST) criteria.

Inclusion Criteria: Clinical suspicion of intra-abdominal injury Presentation within 24 hours of injury Planned CT of the abdomen/pelvis within 24 hours Ability of patient or legally authorized representative to provide informed consent Exclusion Criteria: Co-existing penetrating abdominal injury Known hypersensitivity reaction to contrast agent Pregnant patients Prisoners No appropriate IV Line able to be inserted Hemodynamic instability at time of enrollment (sustained systolic blood pressure < 90 mm Hg or sustained heart rate (HR) >120 despite initial resuscitation)

Individual participant data collected during the trial will be made available for sharing, after de-identification.

Data will be made available for sharing beginning 9 months after study publication and ending 36 months after article publication.

Individual participant data will be available for sharing with researchers who provide a methodologically sound proposal, in order to achieve the aims in the approved proposal. Proposals should be directed to laura.oh@emory.edu. To gain access, data requestors will need to sign a data use agreement.