Here is a bibliography of prehospital ultrasound references initially assembled in 2013 in preparation of a book chapter. It is neither exhaustive nor kept current, although noteworthy references are added intermittently.
Does prehospital ultrasound improve treatment of the trauma patient? A systematic review Eur J Emerg Med. 2010 Oct;17(5):249-53 No evidence in the literature at the time that prehospital US of the abdomen or thorax improves treatment of trauma patients.
Paramedic application of ultrasound in the management of patients in the prehospital setting: a review of the literature Emerg Med J. 2010 Sep;27(9):702-7 Literature review concluding that some paramedic groups are able to obtain ultrasound images of sufficient quality to positively identify catastrophic pathologies found in critically ill patients.
Use of ultrasound by emergency medical services: a review Int J Emerg Med. 2008 December; 1(4): 253–259 Based on current literature, it is difficult to draw conclusions regarding the optimal training criteria for prehospital providers.
Ultrasound applications in mass casualties and extreme environments Crit Care Med. 2007 May;35(5 Suppl):S275-9 Hospital triage assisted by ultrasound after Earthquakes in Armenia in 1988 and Turkey in 1999. Terrestrial FAST examinations rely on gravitational pooling of fluid by imaging the most dependent portions of the peritoneum for free fluid. FAST shown to be feasible in microgravity environments during parabolic flight, with perihepatic fluid being most reliably detected in animal models. Non-physicians successfully conducted FAST in orbit on the international space station under remote guidance from an earth-based radiologist.Pneumothorax examination appeared in one animal-based study to be more sensitive in the microgravity environment, perhaps because of a more uniform distribution of air in the absence of gravity. Same concept with pleural fluid: no posterior to anterior progression with increasing fluid volume – distribution is more uniform.
Portable ultrasound for remote environments, Part I: Feasibility of field deployment J Emerg Med. 2011 Feb;40(2):190-7 Deployment of lightweight portable ultrasound in the field (by emergency medical services, military operations, disaster relief, medical missions, and expeditions to austere environments) is examined
Portable ultrasound for remote environments, part II: current indications J Emerg Med. 2011 Mar;40(3):313-21 Remote areas, rural clinics in developing countries, expeditions, military, jungle, high altitude and space are some of the austere environments in which ultrasound can be used. Remote viewing has been employed in several services.”Such real-time guidance may decrease the initial training time and learning curve for onsite providers, as ultrasound image acquisition can be assisted (and images may be interpreted) by experts remotely. This “train-as-you-go” model is also employed aboard the International Space Station” Machines need to be inexpensive, lightweight, rugged, have good battery life, be able to withstand extremes of temperature, have rapid boot-up times, and allow transmission of image data. Long list of field-based applications provided.
Prehospital Emergency Ultrasound: A Review of Current Clinical Applications, Challenges, and Future Implications Emerg Med Int. 2013; 2013: 531674 Short review with free full text available
Prehospital ultrasound of the abdomen and thorax changes trauma patient management: A systematic review. Injury. 2015 Jul 26. pii: S0020-1383(15)00419-2. [Epub ahead of print] 992 studies identified, but only three were of sufficiently quality (low risk of bias), and each provided examples of prehospital ultrasound positively changing patient management. Authors conclude: there is moderate evidence that supports prehospital physician use of ultrasound for trauma patients; for some patients, management was changed based on the results of the PHUS; the benefit of ultrasound use in non-physician services is unclear.
Evaluation of prehospital ultrasound
Portable ultrasound in pre-hospital emergencies: a feasibility study Acta Anaesthesiol Scand. 2006 Jul;50(6):754-8 Prospective study using sonography in pre-hospital patient management. Exam time limited to 3 mins on scene. Good visualization was obtained in 74% (n 1⁄4 26), moderate in 26% (n 1⁄4 9). Median examination time was 2.5 min (range 1–3 min). Nine patients (26%) showed positive sonography findings. Sensitivity was 90%, specificity 96%. Diagnostic usefulness was high in undetermined cardiac arrest and hypotension and massive hematoperitoneum. Norwegian author M Busch described the ‘PHASE’ exam (Pre-Hospital Application of Sonography in Emergencies) which combined lung, heart, and peritoneal scanning – similar in principle to and overlapping in technique with other combined protocols published later such as RUSH, UHP and ACES
Prehospital Ultrasound by Paramedics: Results of Field Trial Acad Emerg Med. 2010 Jun;17(6):624-30 High rate of accuracy in FAST and abdominal aorta scanning by paramedics after short training
Prehospital ultrasound imaging improves management of abdominal trauma Br J Surg. 2006 Feb;93(2):238-42 Using PFAST led to a change in either prehospital therapy or management in 30 per cent of patients, and a change to admitting hospital in 22 per cent. In only 7% PFAST was incomplete owing to unfavourable circumstances for conducting ultrasound. These included failure to obtain a clear image or technical failure, because of bright sunlight in one case, artifacts due to air emphysema in two patients with severe thoracic trauma, or gross obesity of four patients. On average, PFAST was performed 35(13) min earlier than ultrasound or CT in the receiving hospital. PFAST had a sensitivity, specificity and accuracy of 93 (95 per cent c.i. 76 to 99) per cent, 99 (95 per cent c.i. 97 to 100) per cent and 99 (95 per cent c.i. 96 to 100) per cent, respectively. There was no correlation between the location of free fluid detected by PFAST and the need for subsequent laparotomy. In 42 patients (21percent), prehospital care at the trauma scene was changed because of the findings of PFAST. Mostly fluid resuscitation was modified by reducing volume replacement in order to reduce blood loss by permissive hypotension, once significant head injury was excluded. In 61 patients (30 per cent), prehospital management was also changed. When intra-abdominal bleeding was found on PFAST, the overall management at the scene was influenced to avoid any therapy beyond advanced life support. Additional therapy was either omitted or performed more quickly in order to shorten the time to surgery. If PFAST was negative, deliberated rescue of patients who were trapped could go ahead. The report from the scene to the receiving trauma centre was supplemented by the findings of PFAST in 105 patients (52 per cent), and in 44 patients (22 per cent) the choice of receiving hospital was changed. As a result of additional information, all trauma teams modified their preparations by including an abdominal surgeon and preparing theatre for urgent laparotomy. Early follow-up of the 28 patients who had intra- abdominal bleeding showed that laparotomy was needed in 12 patients, including seven who had splenectomy. Fourteen patients had no surgical intervention and two died before surgical control of the haemorrhage. One of the two with a false negative PFAST required laparotomy; the other was managed conservatively Intra-abdominal bleeding is a dynamic situation and therefore one explanation for the false negative findings might be that the ultrasound examination was performed so soon after the trauma that haemorrhage due to splenic laceration was not yet apparent enough to give a positive result11. Therefore, it is suggested that PFAST should be repeated every 15 min during the prehospital period interval if the initial PFAST findings are negative but physical examination is suspicious. This may be only a minor advantage in an urban setting, but in rural hospitals with less experience in treating life-threatening injuries, PFAST gives the surgeons more information and more time to prepare.
Prehospital ultrasound in emergency medicine: incidence, feasibility, indications and diagnoses Eur J Emerg Med. 2010 Oct;17(5):254-9 German prehospital physicians ultrasounded 144 of 971 patients (14.8%). Difficult screen visualisation due to ambient lighting in a few cases. In 110 patients examined (76.4%) clinical results were available. In these cases, sensitivity was 85% and specificity was 100%. The positive predictive value was 100%, negative predictive value was 95.5% and accuracy was 96.4%. Exam time 1-2 minutes. Useful for triage in multi-casualty scenarios. Frequently, the best approach was not available because of, for example, stiff neck, splints or vacuum mattress. Phased array transducers preferred for their small footprint.
Use of point-of-care ultrasound by a critical care retrieval team Emerg Med Australas. 2007 Dec;19(6):547-52 Potential benefits of retrieval ultrasound described: Early diagnosis and commencement of appropriate treatment; decreased risk of iatrogenic injury in patients requiring invasive procedures; enhanced accuracy of communication with receiving hospitals on likely management and personnel requirements; decreased time to definitive care. Ultrasound shown to have no electromagnetic interference with aircraft systems. In prehospital missions on scene scans restricted to excluding pneumothorax prior to flight; FAST scans done in flight. Multiple uses in interhospital missions, including vascular access and echocardiography. Avoided unnecessary invasive pro- cedures in four patients in whom chest tube thoracos- tomy was considered but ultrasound revealed was not indicated.
Usefulness of hand-held ultrasound devices in out-of-hospital diagnosis performed by emergency physicians Am J Emerg Med. 2006 Mar;24(2):237-42 In 302 ultrasound exams done out of hospital by French SAMU physicians, diagnostic accuracy was improved (ie, positive USS) in 181 (67%) cases, decreased it (ie, negative USS) in 22 (8%) cases, and was not contributive (ie, USS was 0) in 67 (25%) cases. ‘Difficult screen visualization because of ambient luminosity sometimes happened’. Examinations performed to diagnose peritoneal and/or pleural effusion were the most frequent.
Five-year Retrospective Review of Physician and Non-physician Performed Ultrasound in a Canadian Critical Care Helicopter Emergency Medical Service Prehosp Emerg Care. 2016 Jul 19:1-8. PHUS was used in 455 missions, 318 by non-physician crew and 137 by physicians. In combined trauma and medical patients, in the non-physician group interventions were supported by PHUS in 26% of cases (95% CI 18-34). For transport physicians the percentage support was found to be significantly greater at 45% of cases (95% CI 34-56) p = < 0.006. Incomplete PHUS scans were common and reasons included patient obesity, lack of time, patient access, and clinical reasons
Accuracy of prehospital focused abdominal sonography for trauma after a 1-day hands-on training course Emerg Med J. 2010 May;27(5):345-9 On scene FAST by prehospital physicians was accurate after a one-day course.
The F.A.S.T.E.R. trial. Focused assessment by sonography in trauma during emergency retrieval: a feasibility study Injury. 2008 May;39(5):512-8 Retrieval physicians obtained four quadrant FASTs in helicopter flight in majority of patients. Problems reported by scanning physicians were increased difficulties obtaining views in larger patients (overweight and obese) in body quadrants next to helicopter bulkheads. This was the LUQ view in the BK 117 where patients are loaded in a longitudinal fashion on the right side of the helicopter. hilst patient size impacted on ease of access to ultrasound viewing windows, it did not impact on quality of image production. Scanning physicians needed to be able to scan using either the right or left hand depending on how patients were loaded. This skill requirement was not anticipated prior to the commencement of the trial and is likely to be specific to the retrieval environment. Ultrasound scanning of the patients required the scanning physician to get out of their seat harness restraints. In some patients to complete the scan required loosening or release of the patient restraints as well. This required good communica- tion with pilot and crewman to ensure that flight conditions allowed this to occur without compromis- ing patient or crew safety. There were no issues with ambient light affecting image viewing by scanning physicians. Obtaining adequate ultrasound images was not affected by rotary wing vibration or motion. In assessing ultrasound feasibility whilst en-route, we ensured there would be no impact on time to definitive care by prolonging scene time.
Prehospital and Emergency Department Ultrasound in Blunt Abdominal Trauma Eur J Trauma Emerg Surg 2009;35:341–6 Similar time (average around 2.5 minutes)to undertake p-FAST as FAST, with similar accuracy rates
Diagnostic accuracy of focused assessment with sonography for trauma (FAST) examinations performed by emergency medical technicians. Prehosp Emerg Care. 2012 Jul-Sep;16(3):400-6 EMTs in Korea showed a high diagnostic performance that was comparable to that of surgeons and physicians when detecting peritoneal cavity free fluid in a Korean emergency department setting
Paramedic-performed Focused Assessment with Sonography in Trauma (FAST) in the emergency department Ulus Travma Acil Cerrahi Derg. 2011 Mar;17(2):113-6 Turkish ED-based study showing paramedics could achieve similar sensitivity and specificity to physicians with FAST scans
Evaluation of a thoracic ultrasound training module for the detection of pneumothorax and pulmonary edema by prehospital physician care providers BMC Med Educ. 2009 Jan 12;9:3 A brief training module improved prehospital physicians’ image recognition of pneumothorax and pulmonary oedema
Prehospital chest emergency sonography trial in Germany: a prospective study Eur J Emerg Med. 2012 Jun;19(3):161-6 Sonography was incorporated into prehospital management of patients with acute dyspnoea screening for pleural and pericardial effusion, right heart distension, and pneumothorax. Ultrasonography provided a helpful tool in n=38/56 (68%), and additional therapeutic consequences were drawn in n=14 (25%)COPD, heart failure, acute coronary syndromes
Ultrasound detection of the sliding lung sign by prehospital critical care providers Am J Emerg Med. 2012 Mar;30(3):485-8 Critical care paramedics and nurses successfully identified presence or absence of sliding lung sign in cadaveric model after brief training and retained skills months later.
Acquisition and interpretation of focused diagnostic ultrasound images by ultrasound-naive advanced paramedics: trialling a PHUS education programme Emerg Med J, 2012 vol. 29 (4) pp. 322-326 This UK study showed that paramedics could successfully acquire and identify lung ultrasound images after a two day course. The course covered the identification and management of patients who present with serious thoracic injury, with a specific focus on the use of thoracic ultrasound during early prehospital assessment. Standard 2D images for pleural sliding and comet tails and M-Mode for the ‘seashore sign’ were acquired, and colour Doppler was also used to assist in the identification of pleural sliding
A Pilot Study Examining the Viability of a Prehospital Assessment with UltraSound for Emergencies (PAUSE) Protocol J Emerg Med. 2012 May 15. [Epub ahead of print] 2 hour training of EMT-Ps enabled them to identify pleural sliding, cardiac motion, and pericardial fluid (the PAUSE Protocol)
Cardiac Movement Identified on Prehospital Echocardiography Predicts Outcome in Cardiac Arrest Patients Prehosp Emerg Care. 2012 Jan 11. [Epub ahead of print] Cardiac standstill on echo was a better predictor than other commonly recognised factors associated with outcome: the presence of asystole, down time, bystander CPR, or end-tidal CO2 levels.
Focused echocardiographic evaluation in life support and peri-resuscitation of emergency patients: A prospective trial Resuscitation. 2010 Nov;81(11):1527-33 Evaluate the feasibility of FEEL by German emergency physicians in pre-hospital resuscitation for shock or arrest. Images of diagnostic quality were obtained in 96% and echocardiographic findings altered management in 78% of cases.
Prehospital ultrasound detects pericardial tamponade in a pregnant victim of stabbing assault Resuscitation. 2008 Jan;76(1):146-8 Prehospital detection of tamponade resulting in pericardiocentesis and ROSC; subsequent maternal recovery.
Difficulties encountered by physicians in interpreting focused echocardiography using a pocket ultrasound machine in prehospital emergencies Eur J Emerg Med. 2015 Feb;22(1):17-22 After 2 days training one, two, or three views were graded as adequate or optimal in 86, 65, and 35 patients, but interoperator agreement on findings when compared with an expert was weak, especially for IVC measurement
Prehospital Evaluation of Effusion, Pneumothorax, and Standstill (PEEPS): Point-of-care Ultrasound in Emergency Medical Services West J Emerg Med. 2015 Jul;16(4):503-9 After a focused lecture, prehospital providers and students could accurately identify images of pericardial effusion, pneumothorax, and cardiac standstill.
Training paramedics in focussed echo in life support Eur J Emerg Med. 2015 Dec;22(6):430-5 Paramedics obtained and interpreted echo views in simulated scenarios after a one day training course.
Pre-hospital transcranial Doppler in severe traumatic brain injury: a pilot study Acta Anaesthesiol Scand. 2011 Apr;55(4):422-8 Pre-hospital transcranial Doppler by a French SAMU physician influenced treatment decisions, including the pre-hospital administration of noradrenaline (norepinephrine).
Feasibility of transcranial Doppler ultrasound examination out- of-hospital Resuscitation. 2010 Jan;81(1):126-7 Case report of a French SAMU physician performing TCD on a TBI patient during transport
Transcranial ultrasound from diagnosis to early stroke treatment. 1. Feasibility of prehospital cerebrovascular assessment Cerebrovasc Dis. 2008;26(6):659-63 Prehospital emergency assessment of intracranial arteries using portable duplex ultrasound devices is feasible with bilateral visualisation and Doppler flow measurements of the middle cerebral artery.
Transcranial ultrasound from diagnosis to early stroke treatment: part 2: prehospital neurosonography in patients with acute stroke: the Regensburg stroke mobile project Cerebrovasc Dis. 2012;33(3):262-71 Prehospital diagnosis of MCA occlusion in stroke patients is feasible using portable duplex ultrasonography with or without administration of a microbubble contrast agent.
The use of point-of-care ultrasound by a critical care retrieval team to diagnose acute abdominal aortic aneurysm in the ﬁeld Emerg Med Australas. 2007 Feb;19(1):71-5 Correct diagnosis of leaking abdominal aortic aneurysm made in patient misdiagnosed with acute myocardial infarction with the help of portable ultrasound by a medical retrieval team
Fetal evaluation for transport by ultrasound performed by air medical teams: A case series Air Med J. 2004 Jul-Aug;23(4):32-4 The Fetal Evaluation for Transport with Ultrasound (FETUS) is a screening examination that consists of an evaluation of the fetal heart rate, position, and movement and general condition of the placenta. The examination can be repeated in flight with no acoustic distortion from rotor noise. Cases described where breech position, normal full-term gestation, and fetal distress (bradycardic episodes and lack of amniotic fluid) were detected using bedside ultrasound. In each case, the ultrasound altered patient management.
The ultrasound identification of simulated long bone fractures by prehospital providers Wilderness Environ Med. 2010 Jun;21(2):137-40 Using a turkey leg bone model, EMTs correctly identified the presence or absence of a fracture in the no fracture, transverse fracture, and oblique fracture models 95% of the time. They always correctly identified the presence of a fractured model when assessing the comminuted and segmental fracture models. Across all fracture patterns, a final detection sensitivity of 97.5% (95% confidence interval [CI]: 94.1%-100.0%) and a specificity of 95.0% (95% CI: 85.4%-100.0%) were observed
Feasibility of ultrasound in the helicopter Intensive Care Med. 1998 Oct;24(10):1119 Successful image acquisition and interpretation of truncal ultrasound in a helicopter: “ultrasound examination was not hindered by vibrations or interferences, and the device was not an encumbrance.”
Ultrasonography in Air Ambulance Services Air Rescue 2012;2(1):16-21 Summary of the widespread application of ultrasound by flight physicians in Scandinavia
Ultrasound in HEMS: Its Role in Differentiating Shock States Air Med J. 2003 Mar-Apr;22(2):33-6
Aeromedical trauma sonography by flight crews with a miniature ultrasound unit Prehosp Emerg Care. 2001 Oct-Dec;5(4):399-402 Non physician flight team had three hour training in FAST. Exam could not be performed in 34 patients (48%) due to insufficient time (67%), inadequate patient access, or combativeness. Technical difficulties (difficult screen visualization due to ambient lighting, battery failure, and machine malfunction) prevented scanning in seven (19%) of the 37 in whom it was attempted. In those in whom scanning was successful, the pelvic view was most commonly obtained followed by the right upper quadrant (RUQ) and left upper quadrant (LUQ). They concluded: “Significant advances in training, technology, and/or patient access will be necessary for aeromedical FAST to be feasible.” That was 11 years ago. Their wish came true. ￼
Trauma Ultrasound Feasibility during ￼Helicopter Transport Air Med J. 2000 Oct-Dec;19(4):144-6 14 actual and simulated trauma patients underwent 21 FAST exams in flight by a mixed faculty. Mean exam time was 3 minutes. Median difficulty scale from 0-5 rated as 1 for patient positioning and 0 for other factors.
Is Point-of-Care Ultrasound Accurate and Useful in the Hands of Military Medical Technicians? A Review of the Literature Mil Med. 2012 Aug;177(8):983-7 Multiple studies demonstrate the feasibility of training military medics in US. Even under austere conditions, the majority of studies conclude that medic can perform US with a high degree of accuracy. Mainly pneumothorax, cardiac activity, and musculoskeletal injuries particularly fractures.
Use of ultrasonography to avoid an unnecessary procedure in the prehospital combat environment: a case report Prehosp Emerg Care. 2006 Oct-Dec;10(4):502-6 A blast victim with apparent thoracic trauma at a military aid station without radiographic facilities was subsequently safely evacuated without a chest tube because E-FAST excluded pneumothorax.
Pilot study to determine the feasibility of training Army National Guard medics to perform focused cardiac ultrasonography Prehosp Emerg Care. 2010 Jan-Mar;14(1):118-23 With very minimal training, the vast majority of the army medics in the study who were EMT-B trained were able to rapidly perform a focused basic echo on live models that was adequate to assess for the presence of cardiac activity.
Ultrasonography in the evaluation of hemoperitoneum in war casualties Mil Med. 1999 Aug;164(8):600-2 Test characteristics of FAST in war casualties in military setting similar to civilian.
The utility of handheld ultrasound in an austere medical setting in Guatemala after a natural disaster Am J Disaster Med. 2007 Sep-Oct;2(5):249-56 Hand held ultrasound unit was taken to the site of a natural disaster in Guatemala
Portable ultrasonography in mass casualty incidents: The CAVEAT examination World J Orthop. 2010 November 18; 1(1): 10–19 Proposed protocol examining chest, abdomen, vena cava, and extremities in acute triage during multi-casualty incidents
Application of Tele-Ultrasound in Emergency Medical Services Telemed J E Health. 2008 Oct;14(8):816-24 An emergency medical technician can provide an emergency physician with a patient’s ultrasound images and medical information during the patient’s pre-hospitalization and transportation period using a combination of the Mobile Hospital Emergency Medical System (MHEMS), the portable ultrasound scanner, and the onboard 3G communication capabilities – in Taiwan.
Field testing of a remote controlled robotic tele-echo system in an ambulance using broadband mobile communication technology J Med Syst. 2008 Jun;32(3):235-42 Japanese study in which abdominal ultrasound in an ambulance was remotely operated from hospital. The quality of the ultrasound images that were transmitted over the public mobile telephone networks and those transmitted over the Multimedia Wireless Access Network (a private networks) were compared. The transmission rate over the public networks and the private networks was approximately 256 Kbps, 3 Mbps respectively. Our results indicate that ultrasound images of far higher definition could be obtained through the private networks.
Real-Time Tele-echocardiography: Diagnosis and Management of a Pericardial Effusion Secondary to Pericarditis at an Antarctic Research Station Telemed J E Health. 2012 Sep;18(7):521-4 Intercontinental echo review and consultation for man in Antarctica with a pericardial effusion.
Tele-ultrasound and paramedics: real-time remote physician guidance of the Focused Assessment With Sonography for Trauma examination Am J Emerg Med. 2011 Jun;29(5):477-81 Paramedics with no prior ultrasound experience could obtain FAST images under remote guidance from experienced EPs in less than 5 minutes
Just-in-Time Cost-Effective Off-the-Shelf Remote Telementoring of Paramedical Personnel in Bedside Lung Sonography-A Technical Case Study Telemed J E Health. 2012 Dec;18(10):807-9