Maura Schlussel, MS4
The Article: Zahran, T., El Sayed M.J. Prehospital ultrasound in trauma: A review of current and potential future clinical applications. J Emerg Trauma Shock. 2018 Jan-Mar; 11(1); 4-9.
The Idea: Ultrasound has been shown to improve diagnostic accuracy of trauma patients in the hospital setting, but it is critical to understand the role of ultrasound for trauma management in the prehospital setting. The “golden hour” during which trauma patients are managed before arriving at a facility is the most important predictor of mortality in acute trauma. Ultrasound can be used in the emergency department to quickly and accurately diagnose life-threatening injuries, but with the advent of handheld ultrasound devices, the role of ultrasound in prehospital management of trauma patients is now being investigated. This study is a review article summarizing the current literature on the role of prehospital ultrasound in penetrating and blunt trauma.
The Study: This study is a review article summarizing all available evidence on prehospital ultrasound use in trauma. 3528 articles were identified using PubMed. The authors searched for articles published between 1990 to 2017. They also conducted a hand search to identify relevant articles that were missed by the automatic search.
Inclusion criteria: Articles were selected for inclusion if the use of prehospital ultrasound in trauma was discussed. No limit on the type of article was set.
Exclusion criteria: Articles were excluded if they examined ultrasound use in a hospital setting or if ultrasound was used for a nontrauma cause. Some small case studies were excluded to fit the reference limit for this article.
Results:
● In a prospective multicenter study, prehospital FAST (PFAST) improved diagnostic accuracy, changed prehospital management for 30% of patients, and changed hospital disposition in 22% of cases. PFAST was found to be a reliable tool for triage at a trauma scene.
● Multiple air rescue services have found FAST to be possible during air transport without increasing transit time.
● Handheld ultrasound devices were comparable to formal FAST exams in detecting intraperitoneal fluid but should be complemented with a CT scan.
● Prehospital FEER (focused echo evaluation during resuscitation) detected tamponade with a sensitivity and specificity of 93% and 99%, respectively.
● Prehospital ultrasound detection of pneumothorax was found to be more sensitive than a CXR and prevented unnecessary needle decompression in the field. When ultrasound was not used, 26% of patients who received prehospital needle decompression were later found to not have a pneumothorax on CXR and CT.
● Adequate FAST exams have been completed in harsh environments including the International Space Station, Mount Everest, refugee camps, and in military combat. There is no clear evidence on the benefit of prehospital ultrasound in mass casualty incidents.
● Use of ultrasound changed the prehospital management for 30% of blunt trauma patients, changed the hospital destination of 22% of patients, and allowed hospitals to be notified sooner to activate massive transfusion protocols and prepare operating rooms.
● Ultrasound has been successfully used in the field to confirm endotracheal and gastric tube placements, detect intracranial hematomas, and diagnose fractures.
● While there are no standardized training requirements for prehospital ultrasound, most curriculums involve a didactic course followed by hands-on assessments. Successful training programs ranged from hours to months-long.
● Transmission of ultrasound images taken by EMS providers and interpreted by physicians, also known as tele-guided ultrasound, has been useful in remote locations. Declining image quality over satellite transmission have limited its use.
Takeaway:
Prehospital FAST and FEER have been shown to increase diagnostic accuracy, guide management decisions, assist in triage, and influence transport modality and final hospital destination for patients with blunt or penetrating trauma. Handheld ultrasounds are feasible for use in ambulance and air transport, as well as in austere environments. EMS crews can be trained to accurately perform and interpret prehospital ultrasounds through didactic and proctored assessments, and telemedicine can allow clinicians to interpret ultrasound findings for EMS if image quality is satisfactory. In the future, prehospital ultrasound may he used therapeutically to provide acoustic hemostasis in trauma patients.
Limitations: No large study has shown whether prehospital ultrasound influences morbidity or mortality of trauma patients.