Abstract and Introduction
Introduction: In the United States, there are limited studies regarding use of prehospital ultrasound (US) by emergency medical service (EMS) providers. Field diagnosis of life-threatening conditions using US could be of great utility. This study assesses the ability of EMS providers and students to accurately interpret heart and lung US images.
Methods: We tested certified emergency medical technicians (EMT-B) and paramedics (EMT-P) as well as EMT-B and EMT-P students enrolled in prehospital training programs within two California counties. Participants completed a pre-test of sonographic imaging of normal findings and three pathologic findings: pericardial effusion, pneumothorax, and cardiac standstill. A focused one-hour lecture on emergency US imaging followed. Post-tests were given to all EMS providers immediately following the lecture and to a subgroup one week later.
Results: We enrolled 57 prehospital providers (19 EMT-B students, 16 EMT-P students, 18 certified EMT-B, and 4 certified EMT-P). The mean pre-test score was 65.2%±12.7% with mean immediate post-test score of 91.1%±7.9% (95% CI [22%–30%], p<0.001). Scores significantly improved for all three pathologic findings. Nineteen subjects took the one-week post-test. Their mean score remained significantly higher: pre-test 65.8%±10.7%; immediate post-test 90.5%±7.0% (95% CI [19%–31%], p<0.001), one-week post-test 93.1%±8.3% (95% CI [21%–34%], p<0.001).
Conclusion: Using a small sample of EMS providers and students, this study shows the potential feasibility for educating prehospital providers to accurately identify images of pericardial effusion, pneumothorax, and cardiac standstill after a focused lecture.
The use of bedside point-of-care ultrasound (US) in the emergency department (ED) has been increasing over the past two decades, and is now routinely used by emergency physicians as part of the diagnostic workup of sick patients and screening of trauma victims. It has decreased the time to life-saving interventions for many conditions. For example, use of the extended-focused assessment with sonography for trauma (E-FAST) exam by emergency physicians accurately identifies fluid in the abdomen requiring urgent blood transfusion or exploratory laparotomy, pericardial effusion requiring immediate evacuation, or pneumothorax requiring immediate decompression.[1–5] It is now considered standard-of-care in advanced trauma life support.
Emergency medical service (EMS) providers have the opportunity to diagnose, initiate treatment, and stabilize life-threatening conditions within the first critical minutes of a patient's decompensation. US has been used by physicians, flight nurses, and EMTs, on both ground and air ambulance teams in several countries in Europe as well as by emergency physicians in military combat. Several international studies have shown prehospital bedside US can be conducted with accurate interpretation by physician and non-physician providers, allowing specific interventions to be performed or hospital preparations to be made.[9–12] These studies were of emergency or prehospital physicians, or trained sonographers.[8,11–12] To date, there is limited literature on the use of prehospital US in the United States.
Prior studies have demonstrated that flight medics and ground EMS providers can obtain and interpret images for abdominal aortic aneurysm assessment, FAST exam screening, and cardiothoracic US images.[13–16] A recent case report demonstrated that prehospital emergency US allowed paramedics to accurately identify a clinically significant pericardial effusion in a stabbing victim, allowing them to report this to the trauma surgeon prior to arrival. A recent 2013 study (the PAUSE pilot) examined professional paramedics' ability to acquire and interpret images using a protocol to diagnose pneumothorax, pericardial effusion, or cardiac standstill, finding that after a 2-hour didactic program the providers had an accurate recognition score of 9.1 out of 10. However, this single-center study was limited to 20 trained paramedics. A separate study found that aeromedical prehospital personnel at a Level I trauma center had significant improvement in scores on both a written exam and observed clinical examination after undergoing a structured, 2 month training curriculum. However, these providers were critical care paramedics and nurses who already had significant clinical knowledge, and the study focused primarily on the E-FAST modality. In addition, many of the studies, including the PAUSE pilot, also demonstrate adequate image acquisition ability of prehospital providers,[9,14,18] and that these images are not subject to inaccuracy even when obtained in moving transport vehicles.[12,16]
There remain significant gaps and limitations in existing studies regarding the ability of prehospital providers to acquire and interpret point-of-care US images. Here, we aimed to determine if EMS providers would be able to 1) accurately identify the presence or absence of pericardial effusion, pneumothorax, and cardiac standstill after a one-hour didactic course, and 2) retain the ability to interpret the images over time.
Western J Emerg Med. 2015;16(4):503-509. © 2015 Western Journal of Emergency Medicine