Ultrasound as a tool in prehospital settings: a scoping review

Jose Luis Piñeros-Alvarez; Jose Daniel Yusty Prada; Esteban Portuguez

doi:10.15441/ceem.24.374

Clin Exp Emerg Med > Volume 12(4); 2025 > Article

Piñeros-Alvarez, Prada, and Portuguez: Ultrasound as a tool in prehospital settings: a scoping review

Review Article

Clin Exp Emerg Med 2025; 12(4): 320-330.

Published online: April 30, 2025

DOI: https://doi.org/10.15441/ceem.24.374

Ultrasound as a tool in prehospital settings: a scoping review

Jose Luis Piñeros-Alvarez^1,²

, Jose Daniel Yusty Prada^3,⁴

, Esteban Portuguez^2,⁵

¹School of Medicine, Research Group in Prehospital Care, Emergencies and Disasters (GINAPH), Universidad del Valle, Cali, Colombia

²Faculty of Health, Universidad Santiago de Cali, Cali, Colombia

³SAMU Metropolitano, Santiago, Chile

⁴Omega Capacitaciones, Santiago, Chile

⁵Grupo de Investigación en Salud Integral (GISI), Department of Health Sciences, Faculty of Health, Universidad Santiago de Cali, Cali, Colombia

Correspondence to: Jose Luis Piñeros Universidad del Valle School of Medicine, Health Research Group (GINAPH), Ciudad Universitaria Meléndez, Calle 13 No. 100‑00, Cali 760032, Colombia Email: jose.pineros@correounivalle.edu.co

Received: December 17, 2024 Revised: March 11, 2025 Accepted: March 11, 2025

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/).

Abstract

Point-of-care ultrasound (POCUS) is a valuable tool in the prehospital management of critically ill patients, particularly patients with trauma, dyspnea, or shock. This review aims to evaluate the diagnostic and therapeutic applications, limitations, and implementation challenges of POCUS in prehospital care. Key findings are that ultrasound, particularly the extended Focused Assessment with Sonography in Trauma (eFAST) protocol, offers high specificity in identifying severe hemorrhage in trauma cases, although its sensitivity varies depending on the clinical context and operator experience. In dyspnea, pulmonary ultrasound significantly enhances diagnostic accuracy, aiding early detection of heart failure and other respiratory conditions. For shock, focused echocardiography facilitates rapid diagnosis and timely therapeutic decisions, improving patient outcomes. However, the effectiveness of POCUS is highly dependent on the operator’s expertise, and challenges such as time, space, and resource limitations in prehospital settings may impact its use. Furthermore, local studies in Latin America assessing the impact of prehospital ultrasound on morbidity and mortality reduction are lacking. Based on our review, we recommend standardized training programs, increased availability of portable ultrasound devices, and prospective studies on cost-benefit analysis to optimize POCUS implementation in prehospital systems, particularly in resource-limited regions. Prehospital ultrasound has the potential to revolutionize patient care by improving diagnostic precision and reducing time to definitive treatment, but its successful implementation requires strategic integration of technology, education, and research.

Keywords: Trauma; Wounds and injuries; Emergency medical services; Ultrasound

Capsule Summary

What is already known

Prehospital ultrasound is an emerging tool that enables more objective evaluation of critically ill patients, particularly in cases of trauma, dyspnea, or shock.

What is new in the current study

Key findings demonstrate that ultrasound, particularly the extended Focused Assessment with Sonography in Trauma (eFAST) protocol, offers high specificity in identifying severe hemorrhages in trauma cases, although its sensitivity varies depending on the clinical context and operator experience. In dyspnea, pulmonary ultrasound significantly enhances diagnostic accuracy, facilitating the early detection of heart failure and other respiratory conditions. In cases of shock, focused echocardiography enables rapid diagnosis and timely therapeutic decisions, improving patient outcomes.

INTRODUCTION

Point-of-care ultrasound (POCUS) refers to performing ultrasound based on patient signs or symptoms at the patient’s bedside. It has become a crucial resource in patient care within emergency services and prehospital contexts [1]. Worldwide, many prehospital services have implemented the use of POCUS as a diagnostic and therapeutic support mechanism within their protocols, recognizing that timely care for critically ill patients can be beneficial [2,3].

Literature describing the use of prehospital ultrasound for specific diagnostic and therapeutic interventions is accumulating rapidly, though some studies have raised concerns about the extrapolation of in-hospital sensitivity, specificity, and accuracy of POCUS to prehospital use [4]. Ketelaars et al. [5] described the ABCDE (airway, breathing, circulation, disability, and exposure) approach to ultrasound in prehospital settings, highlighting its usefulness in the initial diagnosis and treatment of traumatized or critically ill patients. By analyzing each component of the protocol (airway, breathing, circulation, disability, and exposure), the authors detailed how ultrasound enables the identification of critical injuries, optimizes interventions, and improves the accuracy of early decision-making. Their review supports the use of portable ultrasound as a key tool for immediate diagnosis in emergency situations, through ultrasound techniques like extended Focused Assessment with Sonography in Trauma (eFAST) for evaluating internal bleeding and abdominal trauma, pulmonary ultrasound for detecting pneumothorax and other respiratory complications, and focused echocardiography to assess cardiac function and circulatory status is crucial in patients with shock, among others.

In Latin American countries, it is uncommon to find prehospital services equipped with POCUS systems. Reasons for this vary, from the cost of acquiring equipment to staff training, which, in fact, is highly variable across Latin America. Similarly, the lack of local studies showing reductions in morbidity and mortality with POCUS application in various prehospital scenarios contributes to the scarcity of POCUS in prehospital settings.

Our objective was to conduct a structured search of the literature using keywords and perform a narrative review of the literature to describe the following: (1) the environments where prehospital ultrasound is used; (2) clinical conditions for using prehospital ultrasound; and (3) current training and education strategies for prehospital staff. Our aim with this review was to complement other more specific reviews on prehospital ultrasound using the following guiding research question, “What are the current environments of use, clinical applications, and key considerations or barriers to the implementation of ultrasound by emergency medical service personnel?”

METHODS

This review was conducted using the scoping review methodology, following the guidelines established by the JBI protocol [6] and the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) checklist [7], designed to enhance transparency and quality in systematic reviews and meta-analyses (Supplementary Material 1).

Eligibility criteria

Studies that met all of the following criteria were included: (1) patients who received ultrasound in a prehospital setting; (2) full-text articles published in indexed journals; (3) original research, including randomized controlled trials, nonrandomized controlled trials, and cohort clinical trials; and (4) articles published in the last 5 years (2019–2024). The following were excluded: (1) duplicate articles, those without a visible abstract in Rayyan (Rayyan; https://www.rayyan.ai/), or those not downloadable for full evaluation; (2) abstracts or full-text articles published as brief communications, letters to the editor, guidelines, websites, or case reports; (3) studies conducted in animals or simulators; and (4) articles in languages other than English or Spanish.

Search strategy

Relevant studies were identified through an electronic search in the PubMed, Scopus, and ScienceDirect databases. The keywords "ultrasonography," "prehospital," and "emergency medical services" were used (Table 1). The search was limited to articles published in English and Spanish during the last 5 years (2019–2024).

Data extraction (selection and coding)

The data extraction process was carried out by two investigators who collected the information; a third investigator verified whether the data met all criteria. Searches were then merged into the Rayyan web application [8], where duplicates were removed and studies were selected for title and abstract evaluation. An analysis of the selected articles was carried out to determine if they met the inclusion and exclusion criteria in a Microsoft Excel (Microsoft Corp) matrix by the investigator. This was done to identify studies that met the inclusion and exclusion criteria and remove duplicate records.

Risk of bias (quality) assessment

After data extraction, agreement and disagreement among the selected articles' content were reviewed by two of the investigators. Discussion and consultation with a third evaluator were held in cases of disagreement among the authors. This also helped avoid selection bias in the included articles/studies.

RESULTS

The literature review identified 8,615 studies from the three mentioned databases. Of these, 533 records were eliminated before the selection phase due to duplicates and the Rayyan automation tool. After limiting the search to articles published between 2019 and 2024, 8,082 records were evaluated by title and abstract, of which 8,020 were excluded (158 by automation tools and 7,862 by investigator selection) A total of 62 studies were read in full text, with 46 studies excluded for not meeting inclusion criteria or having one of the exclusion criteria, leaving 16 articles for comprehensive analysis (Fig. 1).

The included articles address scenarios and strategies for ultrasound use in prehospital care, grouped as shown in Table 2. Results are presented by these groupings. Additionally, bibliographic features are presented and organized in Table 3 [2,3,9–22].

Trauma and eFAST

Five articles evaluated the performance, sensitivity, and specificity of eFAST as a diagnostic strategy for trauma patients in prehospital settings, with a total of 1,740 patients evaluated [2,3,9–11]. These studies retrospectively assessed records taken by prehospital personnel (doctors and paramedics) of trauma victims and compared them to images taken at the receiving emergency center (ultrasound, computed tomography [CT] scan, or surgical findings).

Gamberini et al. [9] reported performing prehospital eFAST in 44 of 199 patients, resulting in identification of 27 positive cases compared to 128 positive cases found in the hospital. They described a general sensitivity of 62.9% and specificity of 100% for positive findings. Additionally, they reported that patients with positive prehospital eFAST findings had a significantly shorter time to CT or surgery (46 minutes vs. 69 minutes, P<0.001). They also noted a significant relationship between eFAST and the Injury Severity Score (ISS) with this time reduction compared to clinical data like hypotension or the Glasgow Coma Scale.

Lucas et al. [10] assessed whether prehospital eFAST influences prehospital strategy and time to surgical treatment based on a randomized controlled trial involving 242 victims. The prehospital team performed a clinical exam or clinical exam supported by eFAST according to a schedule. The results showed that the eFAST-supported clinical exam had better sensitivity and specificity than clinical examination alone (sensitivity of 94.7% and specificity of 97%, compared to 80%). Furthermore, the mean time to hospital admission was significantly reduced by 13 minutes, and time to surgical treatment by 15 minutes with eFAST.

Oliver et al. [2] performed prehospital eFAST on 361 patients, with findings later compared to a CT scan. They reported a sensitivity of 28% and specificity of 98%. Similar data were reported by Stralec et al. [11], who evaluated eFAST performance in detecting severe hemorrhage in 527 patients with an ISS of 11. Fourteen percent of patients had severe hemorrhage, with a positive eFAST result in 38% (sensitivity, 38%; specificity, 87%).

Partyka et al. [3], in a multicenter study involving 411 patients, reported the accuracy of prehospital eFAST for detecting peritoneal fluid (sensitivity, 25%; specificity, 96%), pneumothorax (sensitivity, 38%; specificity, 96%), hemothorax (sensitivity, 17%; specificity, 97%), and pericardial effusion (sensitivity, 17%; specificity, 100%). Most patients were male (73%), were closed trauma cases (98%), and two-thirds were injured in traffic accidents.

Dyspnea

Four publications focused primarily on the diagnosis of respiratory (cardiac or pulmonary) alterations related to the presence of dyspnea as a presenting symptom using lung ultrasound (LUS) [12–15]. Experienced paramedics in LUS evaluated a total of 44 patients with symptoms of dyspnea, and their results were compared with images taken at the receiving hospital [12]. A match of 90.91% was found, with no statistical differences between prehospital care and the emergency department. The same study reports a mean time of 63.66 seconds to obtain the LUS.

A prospective interventional study on patients transported to a hospital by a prehospital system included patients diagnosed with dyspnea as their primary symptom. Sensitivity and specificity for acute heart failure by paramedics were 23.3% and 97.2%, respectively, when LUS was not used, and 71% and 96%, respectively, when LUS was used. The most common alternative final diagnoses were chronic obstructive pulmonary disease (32%), pneumonia (13%), and asthma (8%). Overall, sensitivity increased by 48% without affecting specificity [13].

Gundersen et al. [14] similarly evaluated a group of 214 patients presenting with dyspnea as a symptom during prehospital care. Forty prehospital physicians initially assessed the patients and formed a diagnostic suspicion, then performed LUS and revised their diagnosis. Final records were evaluated by experts who determined the quality and accuracy of the images and diagnosis. Acute heart failure was suspected in 64 of 214 patients (30%) before ultrasound and in 64 of 214 (30%) after ultrasound. Ultrasound led to reclassification in 53 of 214 patients (25%).

Pietersen et al. [15], in their study related to ultrasound in patients with respiratory symptoms, collected 406 ultrasound images taken by paramedics during prehospital care between November 2018 and April 2020 in Denmark. Prior to this, prehospital personnel were trained in thoracic ultrasonography to conduct a retrospective quality control assessment with an evaluator who scored the quality and appropriateness of each image. The result of the review was 87.0% normal, 89.9% for interstitial syndrome, 97.3% for possible pneumothorax, and 96.3% for pleural effusion, with adequate image quality to determine whether pulmonary pathology was present or not.

Cardiopulmonary resuscitation

The use of ultrasound during cardiopulmonary resuscitation (CPR) maneuvers has recently expanded with the advent of portable devices. For out-of-hospital CPR, the literature is still in a growth phase. We identified one study correlating expired CO₂ with ventricular contraction measured by ultrasound [16]. This study evaluated 18 patients, and during resuscitation maneuvers, continuous end-tidal CO₂ (ETCO₂) was measured along with subxiphoid ultrasound at least two or three times throughout the process. The ultrasound allowed for the evaluation of compression indices of the right and left ventricles and the correlation of these indices with ETCO₂. Thoracic compressions induced significant compressions in all the observed cardiac chambers, such as the left ventricle (20.6%±13.8%) and the right ventricle (34.5%±21.6%). A positive correlation between ETCO₂ and compression of the evaluated cardiac chambers was identified.

Prehospital ultrasound with remote assistance

Remote-assisted ultrasound uses telecommunications technologies to transmit images from a remote location to an expert who interprets them in real-time and guides prehospital diagnosis. Remote expert assistance for ultrasound evaluations performed in the prehospital setting promises to improve diagnostic success rates. We identified three publications that reported on prehospital ultrasound with remote assistance in our literature search [17–19].

Hermann et al. [17] obtained prehospital ultrasound images from patients who met any of these criteria: trauma, acute dyspnea, or circulatory failure. Of 24 patients, 58% presented with circulatory failure, with trauma in one case only. Remote supervision was successfully carried out in 17 of 24 cases: three cases did not receive timely supervision, and one case was not supervised due to connectivity issues. Audio issues were experienced in another three cases; these were resolved through a phone call to the expert and were satisfactorily resolved.

Siu et al. [18] evaluated the impact of remote supervision on prehospital personnel performance in performing eFAST in simulated cases. They compared eight supervised cases with eight independently assessed cases, with supervision times of 5 minutes 16 seconds and 8 minutes 27 seconds, respectively. The percentage of correctly identified injuries in the independent versus remote-supervised eFAST was 65% versus 92.5%, with a P-value of 0.01. They reported that prehospital personnel experienced significantly higher mental, temporal, and effort demands, greater frustration, and lower subjective performance during the independent trials.

Similarly, Engelsen et al. [19] evaluated the feasibility of remote-assisted ultrasound during airlift transfer by helicopter. In this case, the prehospital personnel consisted of four anesthesiologists and one military doctor who performed eFAST with remote supervision during nine helicopter flights, each with a unique healthy volunteer. A remote expert radiologist guided the doctors in their examinations. The obtained images were evaluated according to quality criteria described in the document, with an average rating of 4.9, corresponding to good diagnostic quality. The average duration of the teleguided eFAST was 5 minutes 54 seconds. Additionally, they described issues with signal transmission depending on proximity to urban areas and when flying above 2,000 ft (600 m).

Implementation of ultrasound and image recording in prehospital systems

The implementation of ultrasound in prehospital services requires the integration of an image archiving system that allows images to be audited for statistical and practical data, such as the accuracy of image acquisition by prehospital professionals. Aziz et al. [20] described the implementation of an image archiving system and a clinical governance framework in a UK helicopter emergency medical service. During the study period, 5,913 patients were treated, 18.6% of whom had registered POCUS exams. The image quality was similar between doctors and paramedics, with adequate concordance between reviewers and prehospital personnel.

Implementation of ultrasound in prehospital services presents economic, training, and maintenance challenges, among others. Alsulami et al. [21] explored various topics related to implementation, such as perceived barriers, transportation mode, ultrasound familiarity, and stakeholders' self-efficacy in implementing prehospital ultrasound in the Saudi Red Crescent. They found that the primary barrier was the cost of ultrasound equipment and maintenance; other barriers identified were lack of training, skills among staff, and environmental factors that interfered with image quality.

Impact on outcomes

One study evaluated patients who entered the emergency department who were treated by prehospital services and divided these patients into two groups: a group that received POCUS (n=169) and another group that received only standard care before arriving at the emergency department (n=671) [22]. Median length of stay in the emergency department for the prehospital POCUS group was 159 minutes, compared to 165 minutes in the standard care group (P=0.125). Patients evaluated with prehospital POCUS had a shorter stay than those who received only standard care, but without statistical significance.

DISCUSSION

Prehospital ultrasound is a valuable tool for managing critically ill patients, with notable applications in trauma, dyspnea, and shock. Our review found that ultrasound shows good specificity for identifying conditions such as pneumothorax or abdominal fluid, consistent with previous findings [22,23]. However, prehospital eFAST currently has insufficient sensitivity for predicting the presence of injuries compared to imaging performed within the hospital setting. This is likely because a positive eFAST result is highly indicative of a corresponding injury confirmed by CT scans. In critically ill patients, prehospital eFAST provides important information to tailor patient management and direct them to the most appropriate facility. However, negative prehospital eFAST results do not definitively rule out the presence of injuries, and additional studies should be performed once the patient is in the hospital to exclude potential injuries.

Akoglu et al. [23] reported a sensitivity of 40% to 75% for intrahospital eFAST compared to CT scans in identifying thoracic and abdominal injuries. This difference in sensitivity outcomes can be attributed to variation in the conditions experienced in prehospital settings, such as weather, lighting, and noise. Additionally, in the early minutes post-trauma, some conditions, such as hemoperitoneum, pneumothorax, or hemothorax, may still be in very early stages and too small to be detected by ultrasound during initial examination. By the time the patient reaches the hospital, these injuries may have progressed. A recent study recommended serial eFAST examinations as a follow-up method for suspected injuries in hospital settings [24].

Various authors have corroborated that ultrasound and its interpretation are operator-dependent [25,26]. Factors such as the operator's professional background, experience, and training can affect sensitivity and specificity results. While this has been documented in intrahospital research, more studies are needed to address this issue in prehospital environments. Additionally, it is well known that prehospital emergency systems are regulated heterogeneously across countries, with varying professional profiles, training levels, and skills.

Dyspnea can have multiple causes, including abnormalities in the respiratory, cardiac, muscular, or metabolic systems. A recent pilot study in the prehospital setting demonstrated that using ultrasound to evaluate B lines is effective in ruling out acute heart failure, although it lacks specificity to confirm it [14]. Conversely, another small-scale prehospital study indicated that detecting pleural effusion using ultrasound has high sensitivity and specificity for diagnosing acute heart failure [27]. Our review of the literature revealed significant improvement in diagnostic accuracy when ultrasound was used in patients with dyspnea, facilitating early identification of acute heart failure.

Future recommendations

Future research on ultrasound in prehospital settings should include prospective, multicenter, and large-scale studies, especially in countries where publications on this topic are still limited. It is also essential to promote research that evaluates not only the clinical application of ultrasound but also its costs and benefits in prehospital scenarios and its integration with existing healthcare systems. Research efforts should be aligned with the development of training programs tailored to local needs. Standardized protocols will enable more efficient use of ultrasound, ensuring that prehospital professionals can enhance decision-making processes that positively impact the outcomes of critically ill patients.

Conclusions

Prehospital ultrasound is a promising tool with the potential to transform prehospital care by improving diagnostic accuracy and reducing time to definitive treatment. However, its implementation faces significant challenges, particularly in countries with limited resources. The future of prehospital ultrasound depends on comprehensive strategies that combine technology, education, and research to ensure that it has a positive impact on the care of critically ill patients.

NOTES

Author contributions

Conceptualization: all authors; Data curation: EP; Formal analysis: JLPA, EP; Funding acquisition: EP, JLPA; Investigation: JLPA, EP; Methodology: all authors; Resources: JLPA, EP; Software: JDYP; Supervision, JLPA, EP; Validation, JLPA; Visualization: JLPA, EP; Writing–original draft: JLPA, EP; Writing–review & editing: all authors. All authors read and approved the final manuscript.

Conflicts of interest

The authors have no conflicts of interest to declare.

Funding

This study was supported by a grant from the Dirección General de Investigaciones of Universidad Santiago de Cali (No. DGI-01-2025).

Data availability

Data analyzed in this study are available from the corresponding author upon reasonable request.

Supplementary materials

Supplementary materials are available from https://doi.org/10.15441/ceem.24.374.

Supplementary Material 1.

PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) checklist.

ceem-24-374-Supplementary-Material-1.pdf

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12. Kowalczyk D, Turkowiak M, Piotrowski WJ, Rosiak O, Białas AJ. Ultrasound on the frontlines: empowering paramedics with lung ultrasound for dyspnea diagnosis in adults: a pilot study. Diagnostics (Basel) 2023; 13:3412.

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15. Pietersen PI, Mikkelsen S, Lassen AT, et al. Quality of focused thoracic ultrasound performed by emergency medical technicians and paramedics in a prehospital setting: a feasibility study. Scand J Trauma Resusc Emerg Med 2021; 29:40.

16. Skulec R, Vojtisek P, Cerny V. Correlation between end-tidal carbon dioxide and the degree of compression of heart cavities measured by transthoracic echocardiography during cardiopulmonary resuscitation for out-of-hospital cardiac arrest. Crit Care 2019; 23:334.

17. Hermann M, Hafner C, Scharner V, et al. Remote real-time supervision of prehospital point-of-care ultrasound: a feasibility study. Scand J Trauma Resusc Emerg Med 2022; 30:23.

18. Siu M, Dan J, Cohen J, et al. Impact of telemedicine on extended focused assessment with sonography for trauma performance and workload by critical care transport personnel. Air Med J 2023; 42:105-9.

19. Engelsen PC, Heyerdahl F, Maddali DD, et al. Ascending with ultrasound: telementored eFAST in flight: a feasibility study. Emerg Radiol 2024; 31:25-31.

20. Aziz S, Edmunds CT, Barratt J. Implementation of a point-of-care ultrasound archiving system and governance framework in a UK physician-paramedic staffed helicopter emergency medical service. Scand J Trauma Resusc Emerg Med 2024; 32:49.

21. Alsulami M, Almukhlifi Y, Alsulami A, Al Nufaiei ZF, Alruwaili A, Alanazy A. Implementing prehospital ultrasound at the Saudi red crescent authority: perceived barriers and training needs. J Multidiscip Healthc 2024; 17:2871-8.

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Fig. 1.

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flowchart.

Table 1.

Search terms

Database	Search term
PubMed	(((ultrasonography[MeSH Terms])) OR (ultrasound[Title/Abstract])) AND (POCUS[Title/Abstract])) OR (point-of-care ultrasound[Title/Abstract])) OR (eFAST[Title/Abstract])) AND (pre-hospital[Title/Abstract])) OR (prehospital[Title/Abstract]) AND (2018:2025[pdat])
Scopus	(TITLE-ABS-KEY (ultrasonography) OR TITLE-ABS-KEY (ultrasound) AND TITLE-ABS-KEY (pocus) OR TITLE-ABS-KEY (point AND of AND care AND ultrasound) AND TITLE-ABS-KEY (pre-hospital) OR TITLE-ABS-KEY (prehospital)) AND PUBYEAR > 2017 AND PUBYEAR < 2025
ScienceDirect	ultrasonography OR ultrasound AND POCUS OR point-of-care OR eFAST AND pre-hospital OR prehospital OR ambulances

Table 2.

Scenarios and strategies for ultrasound use in prehospital care

Ultrasound use in prehospital care	No. of studies
Trauma and eFAST	5
Clinical dyspnea	4
Remote assistance and supervision	3
Cardiopulmonary resuscitation	1
Implementation	2
Impact on outcomes	1

eFAST, extended Focused Assessment with Sonography in Trauma.

Table 3.

Bibliography features

Study	Country	Study type	No. of patients	Objective	Methods	Results
eFAST
Gamberini et al. [9] (2022)	Italy	Observational retrospective	199	To investigate whether a positive prehospital FAST exam in patients with abdominal trauma could play a role in reducing the time to CT or operating room.	Patients with abdominal trauma taken to a level I trauma center between 2014 and 2019.	Sensitivity, 62.9% (95% CI, 42.4%–80.6%)
					Clinical and laboratory prehospital variables and ED data were collected, as well as intrahospital times during diagnostic and therapeutic pathways.	Specificity, 100% (95% CI, 80.5%–100%).
						Positive prehospital FAST exams indicated a significantly shorter time from door to CT or door to OR (46 min vs. 69 min, P<0.001).
						Only the ISS and prehospital FAST were significantly associated with a reduction in door-to-CT or door-to-OR time in the multivariable model.
Lucas et al. [10] (2022)	Germany	Prospective and randomized clinical trial	242	To evaluate whether prehospital FAST influences the prehospital strategy and time to surgical treatment.	According to a schedule related to calendar weeks, either CEX only or a CEX with prehospital FAST was performed.	CEX with prehospital FAST showed high sensitivity (94.7%) and specificity (97.6%) in detecting free fluid compared to CEX alone (80.0% and 84.4%, respectively).
					The outcome variables were the diagnosis and prehospital strategy, the time until admission to the trauma room and the OR.	The mean time to admission was significantly reduced by 13 min, and time to surgical treatment was reduced by 15 min after CEX with prehospital FAST.
						A crossover rate of 30.8% from prehospital FAST (n=36) to CEX with prehospital FAST was observed during the CEX-only weeks.
Oliver et al. [2] (2020)	UK	Observational retrospective	361	To determine the diagnostic performance of prehospital portable chest ultrasound in trauma patients.	Retrospective review of trauma patients who received prehospital chest ultrasound and were subsequently transferred to Royal Sussex County Hospital between July 1, 2013, and September 24, 2018.	411 Patients were transferred to the hospital, with the largest group being those who had suffered a traffic collision.
					Prehospital ultrasound findings were compared with the CT performed upon arrival at the hospital.	Most of the prehospital ultrasounds (66%) were performed by doctors.
						361 Patients (88%) subsequently underwent a CT scan. Of these, 98 patients (27%) had pneumothorax.
						For the diagnosis of pneumothorax, prehospital ultrasound had a sensitivity of 28% (95% CI, 19%–37%) and a specificity of 98% (95% CI, 97%–99%).
Stralec et al. [11] (2024)	France	Multicenter retrospective study	527	To investigate whether there was an association between the detection of peritoneal or pleural fluid in prehospital ultrasound for trauma and severe posttraumatic hemorrhage.	Data from records of patients with thoracic or abdominal trauma treated from January 2017 to December 2021.	73 Patients (14%) had severe hemorrhage, of whom 28 (38%) had a positive FAST, compared to 61 (13%) without severe hemorrhage (P<0.01).
Stralec et al. [11] (2024)	France	Multicenter retrospective study	527		A multivariate analysis was performed to investigate the predictive performance of the FAST alone or in combination with the five previously validated red flag criteria.	For predicting severe hemorrhage, FAST had a sensitivity of 38% (95% CI, 27%–50%) and a specificity of 87% (95% CI, 83%–90%; AUC, 0.62; 95% CI, 0.57–0.68).
Partyka et al. [3] (2022)	Australia	Observational retrospective	411	To report the relative accuracy of eFAST exams performed prehospital by HEMS physicians in the Sydney Metropolitan Area.	Patients with trauma who underwent prehospital eFAST between January 2013 and December 2017.	Intraperitoneal fluid: sensitivity, 25% (95% CI, 16%–36%); specificity, 96% (95% CI, 93%–98%)
					Measured outcomes include the calculated accuracy of eFAST in detecting free intraperitoneal fluid, pneumothorax, hemothorax, and pericardial fluid compared to available reference outcomes.	Pneumothorax: sensitivity, 38%; specificity, 96%
						Hemothorax: sensitivity, 17%; specificity, 97%
						Pericardial effusion: sensitivity, 17%; specificity, 100%.
Nontraumatic dyspnea
Kowalczyk et al. [12] (2023)	Poland	Prospective observational	44	To evaluate the utility of LUS as an additional tool in the diagnosis of dyspnea when performed by experienced paramedics in real-life prehospital settings.	In the prehospital setting, an experienced paramedic performed a chest ultrasound examination, including the BLUE protocol and the eFAST.	The ultrasound performed by the paramedic was consistent with the discharge diagnosis in 90.91% of the final diagnoses established on the day of hospital discharge.
Kowalczyk et al. [12] (2023)	Poland	Prospective observational	44		The paramedic's diagnosis was compared with the ED diagnosis and, if available, with the final diagnosis established on the day of hospital discharge.	In cases where the patient was treated only in the ED, the prehospital ultrasound was consistent with the ED diagnosis in 88.64% of cases.
Russell et al. [13] (2024)	USA	Nonrandomized prospective	353	To determine the diagnostic accuracy of paramedics with and without the use of LUS for the diagnosis of AHF in patients with dyspnea in the prehospital setting; and to evaluate the impact of LUS on the frequency and time to initiation of treatment for AHF.	Adult patients (>18 yr) with a chief complaint of dyspnea and ventilatory abnormalities were included.	40 Patients underwent LUS performed in the prehospital setting.
					26 Paramedics were trained in LUS, consisting of 30 min of theory, 30 min of practical exploration, and individual completion of a written knowledge assessment and a structured clinical objective exam.	Without LUS: sensitivity, 23.3% (95% CI, 28%–41%); specificity, 97.2% (95% CI, 93%–99%); positive likelihood ratio, 8.59 (95% CI, 3–24); negative likelihood ratio, 0.79 (95% CI, 0.69–0.89)
						With LUS: sensitivity, 71% (95% CI, 44%–88%); specificity, 96% (95% CI, 76%–99%); positive likelihood ratio, 16.2 (95% CI, 2.3–113.1); negative likelihood ratio, 0.31 (95% CI, 0.15–0.65)
Gundersen et al. [14] (2023)	Denmark	Prospective observational	214	The hypothesis was raised that complementing the CEX with POCUS would increase sensitivity for diagnosing AHF compared to the CEX alone.	Prehospital care doctors recorded a suspected diagnosis based solely on the CEX, performed POCUS of the heart and lungs, and finally recorded the suspected diagnoses based on their CEX complemented with POCUS.	Suspected AHF: before POCUS, 64 (30%); after POCUS, 64 (30%); reclassification, 53 (25%)
					The diagnoses before and after POCUS were compared with the diagnoses assigned by the adjudication committee.	The adjudication committee assigned a diagnosis of AHF in 87 (41%).
						Sensitivity for AHF: before POCUS, 58% (95% CI, 46%-69%); after POCUS, 65% (95% CI, 53%–75%)
Pietersen et al. [15] (2021)	Denmark	Retrospective quality control	100	To explore the quality of thoracic ultrasound exams performed on patients by EMTs and paramedics in a prehospital clinical setting.	Danish EMTs and paramedics (n=100) performed thoracic ultrasound exams on patients with respiratory symptoms using a portable ultrasound device.	A total of 590 ultrasound exams were evaluated, resulting in a median image quality score of 3 (IQR, 3–4).
Pietersen et al. [15] (2021)	Denmark	Retrospective quality control	100		The ultrasound exams were stored and retrospectively evaluated by a reviewer blind to the patients' symptoms and history. The image quality was scored from 1 to 5.	The overall percentage agreement between the EMTs and paramedics and the reviewer was high (87.7% for a normal scan, 89.9% for interstitial syndrome, 97.3% for possible pneumothorax, and 96.3% for pleural effusion).
CPR
Skulec et al. [16] (2019)	Czech Republic	Clinical trial	18	To evaluate whether the degree of compression of the RV and LV induced by chest compressions during CPR and measured by transthoracic echocardiography correlates with the EtCO₂ levels measured at the time of the echocardiographic investigation in a prehospital setting.	Continuous EtCO₂ monitoring and subxiphoid ultrasound were performed at least two or three times during the entire process of CPR.	Chest compressions induced significant compressions of all the observed heart chambers (e.g., LV, 20.6%±13.8%, RV, 34.5%±21.6%).
Skulec et al. [16] (2019)	Czech Republic	Clinical trial	18		The ultrasound allowed the assessment of the compression indices of the RV and LV and the correlation of these indices with the EtCO₂ levels.	A positive correlation was identified between EtCO₂ and the compressions of the evaluated heart chambers.
Remote assistance and supervision
Hermann et al. [17] (2022)	Austria	Clinical trial	24	The aim is to evaluate the feasibility of live data transmission and monitoring of prehospital POCUS in an urban setting, with the goal of improving patient safety.	Prehospital ultrasounds were performed in emergency cases, such as trauma, acute dyspnea, or cardiac shock.	In 17 patients (71%), the prehospital ultrasound with real-time remote supervision was successfully performed.
					The ultrasound examination was remotely transmitted to an expert in emergency ultrasound at the clinic for real-time supervision via a secure video and audio connection.	In three cases, the expert was not available in time, and in one case, remote data transmission was not possible due to connection issues.
					The study analyzed the technical feasibility, as well as the quality of communication and live transmission.
Siu et al. [18] (2023)	USA	Descriptive observational	16	Determine the impact of teletutoring on eFAST performance and quantify the workload experience.	Eight modules of traumatic injuries in simulated patients were selected.	Eight independent eFASTs and eight teleguided eFASTs were completed.
					The prehospital staff was assigned the task of completing an independent eFAST and one guided by an emergency physician.	The average times to complete the independent and teleguided eFAST were 5 min 16 sec (95% CI, 3 min 32 sec–6 min 59 sec) and 8 min 27 sec (95% CI, 5 min 14 sec–11 min 39 sec), respectively (P=0.06).
					The completion time and percentage of correct findings were recorded.
					Participants completed the workload index after each iteration to assess workload.
Engelsen et al. [19] (2024)	Norway	Study to feasibility	5	Examine the feasibility of tele-ultrasound in a helicopter	A total of four anesthesiologists and one military doctor were recruited to perform eFAST with remote supervision during nine helicopter flights, each with a single healthy volunteer.	The remote expert rated the images at 4.9.
					A radiologist was recruited as the remote expert, who guided the doctors in their exams.	The average duration of the teleguided eFAST was 5 min 54 sec.
					The remote expert rated the diagnostic quality of the images on a Likert scale from 1 to 5.	Long-term evolution coverage was negatively affected by proximity to urban areas and ceased above 2,000 ft (600 m) in altitude.
Implementation
Aziz et al. [20] (2024)	UK	Clinical trial	5913	Implementation of a new image archiving system and a robust clinical governance framework in the UK-based helicopter emergency medical service staffed by physicians and paramedics.	A retrospective review of the database of all patients attended between the introduction of a new POCUS device and an image archiving system.	POCUS images were recorded for 1,097 patients, with a prevalence of 18.6%.
					All patients with recorded POCUS examinations were included, and a supervisor reviewed them within 24 hours.	Quality control was performed on 1,061 examinations (96.7%).
					The image quality was rated using a 5-point Likert scale, and the agreement between the reviewer and the physician was recorded.	The most common POCUS modality was echocardiography (60%), primarily during cardiac arrest.
					Feedback on the scanning technique was provided.	Paramedics performed 25.4% of POCUS examinations.
						Across all types of examinations, image quality did not differ significantly between physicians and paramedics.
Alsulami et al. [21] (2024)	Saudi Arabia	Qualitative study	24	To examine the inherent barriers to the implementation of prehospital ultrasound within the Saudi Red Crescent Authority.	Qualitative study to explore the perceived barriers, mode of transport, familiarity with ultrasound, and the level of self-efficacy of relevant stakeholders in the implementation of prehospital ultrasound.	The main barriers to implementing prehospital ultrasound were the cost of equipment, lack of training, and environmental factors affecting image quality.
Alsulami et al. [21] (2024)	Saudi Arabia	Qualitative study	24		Data were collected through surveys and interviews with 24 paramedics/EMTs, 4 station administrators, and 2 hospital doctors.	Administrators and doctors raised concerns about the portability and maintenance of the equipment.
Impact on outcomes
Ienghong et al. [22] (2023)	Thailand	Cross-sectional, observational study	840	To evaluate variations in the length of stay in the ED between the prehospital POCUS group and the standard care group.	A cross-sectional study on prehospital patients admitted to an ED from January to December 2021.	The median length of stay in the prehospital POCUS group was 159 min (IQR, 89– 289 min) compared to 165 min (IQR, 102– 330 min) in the standard care group (P=0.125).
					Two groups were analyzed: patients who underwent prehospital ultrasound (prehospital ultrasound group) and patients who received standard care without prehospital ultrasound (standard care group).	The need for additional diagnostic imaging that extended the ED stay beyond 4 hours was lower in the prehospital POCUS group (adjusted odds ratio, 0.92; 95% CI, 0.729–1.666) compared to the standard care group.
					Prehospital ultrasound and ED medical records were documented and submitted for analysis.

eFAST, extended Focused Assessment with Sonography in Trauma; FAST, Focused Assessment with Sonography in Trauma; CT, computed tomography; ED, emergency department; CI, confidence interval; OR, operating room; ISS, Injury Severity Score; CEX, clinical examination; AUC, area under the curve; HEMS, helicopter emergency medical service; LUS, lung ultrasound; BLUE, Bedside Lung Ultrasound in Emergency; AHF, acute heart failure; POCUS, point-of-care ultrasound; EMT, emergency medical technician; IQR, interquartile range; CPR, cardiopulmonary resuscitation; RV, right ventricle; LV, left ventricle; EtCO₂, end-tidal carbon dioxide.