Feasibility of Paramedic Performed Prehospital Lung Ultrasound in Medical Patients with Respiratory Distress

Contribution of point-of-care ultrasound in the prehospital management of patients with non-trauma acute dyspnea: a systematic review and meta-analysis

Acute dyspnea is a common symptom whose management is challenging in prehospital settings. Point-of-care ultrasound (POCUS) is increasingly accessible because of device miniaturization. To assess the contribution of POCUS in the prehospital management of patients with acute nontraumatic dyspnea, we performed a systematic review on nontrauma patients of any age managed in the prehospital setting for acute dyspnea and receiving a POCUS examination. We searched seven databases and gray literature for English-language studies published from January 1995 to November 2023. Two independent reviewers completed the study selection, data extraction, and risk of bias assessment. The primary outcome was the assessment of the contribution of POCUS to feasibility, diagnostic, therapeutic, prognosis, patient referral, and transport vector modification. Twenty-three studies were included. The risk of bias assessment identified 3 intermediate-risk, 18 serious-risk, and 2 critical-risk studies. Three studies reported moderate to excellent feasibility for lung POCUS, and three studies reported poor to mediocre feasibility for cardiac POCUS. The median duration of the POCUS examination was less than 5 minutes (six studies). POCUS improved diagnostic identification (seven studies). The diagnostic accuracy of POCUS was excellent for pneumothorax (sensitivity = 100%, specificity = 100%, two studies), very good for acute heart failure (sensitivity = 71-100%, specificity = 72-95%, eight studies), good for pneumonia (sensitivity = 88%, specificity = 59%, one study), and moderate for pleural effusion (sensitivity = 26-53%, specificity = 83-92%, two studies). Treatment was modified in 11 to 54% of the patients (seven studies). POCUS had no significant effect on patient prognosis (two studies). POCUS contributed to patient referrals and transport vectors in 51% (four studies) and 25% (three studies) of patients, respectively. The evidence supports the use of POCUS for managing acute nontraumatic dyspnea in the prehospital setting in terms of feasibility, overall diagnostic contribution, and, particularly, lung ultrasound for acute heart failure diagnosis. Moreover, POCUS seems to have a therapeutic contribution. There is not enough evidence supporting the use of POCUS for pneumonia, pleural effusion, pneumothorax, chronic obstructive pulmonary disease, or asthma exacerbation diagnosis, nor does it support prognostic, patient referral, and transport vector contribution. A high level of evidence is lacking and needed.

Prehospital Use of Ultrasound by Paramedics: A Literature Review

Ultrasound technology is widely used in hospital settings throughout the United States to aid in the diagnosis and treatment of various diseases. While the benefits of utilizing ultrasound in hospital settings are well understood, there are prehospital scenarios where the utility of ultrasound could be examined. Prehospital care often addresses acute and time-sensitive medical conditions, in which additional diagnostic information and early pathology detection can be crucial. Given the nature of these conditions, the use of ultrasound by paramedics in the prehospital setting is considered. This narrative review assesses the benefits and challenges of implementing widespread prehospital ultrasound use.

Development and evaluation of a point-of-care ultrasound curriculum for paramedics in Germany - a prospective observational study and comparison

BACKGROUND

Point-of-care ultrasound (POCUS) is steadily growing in use in prehospital emergency medicine. While currently used primarily by emergency physicians, POCUS could also be employed by paramedics to support diagnosis and decision-making. Yet to date, no paramedicine-targeted POCUS curricula exist in Germany. Furthermore, given time and resource constraints in paramedic training, it is unclear whether paramedics could feasibly learn POCUS for prehospital deployment. Hence, this study outlines the development and implementation of a comprehensive POCUS curriculum for paramedics. Through this curriculum, we investigate whether paramedics can attain proficiency in POCUS comparable to other user groups.

METHODS

In this prospective observational study, we first developed a blended learning-based POCUS curriculum specifically for paramedics, focusing on basic principles, the RUSH-Protocol and ultrasound guided procedures. Participants underwent digital tests to measure their theoretical competence before (T1) and after the digital preparation phase (T2), as well as at the end of the on-site phase (T3). At time point T3, we additionally measured practical competence using healthy subjects and simulators. We compared the theoretical competence and the practical competence on a simulator with those of physicians and medical students who had also completed ultrasound training. Furthermore, we carried out self-assessment evaluations, as well as evaluations of motivation and curriculum satisfaction.

RESULTS

The paramedic study group comprised n = 72 participants. In the theoretical test, the group showed significant improvement between T1 and T2 (p < 0.001) and between T2 and T3 (p < 0.001). In the practical test on healthy subjects at T3, the group achieved high results (87.0% ± 5.6). In the practical test on a simulator at T3, paramedics (83.8% ± 6.6) achieved a lower result than physicians (p < 0.001), but a comparable result to medical students (p = 0.18). The results of the study group's theoretical tests (82.9% ± 9.2) at time point T3 were comparable to that of physicians (p = 0.18) and better than that of medical students (p < 0.01). The motivation and attitude of paramedics towards the prehospital use of POCUS as well as their self-assessment significantly improved from T1 to T3 (p < 0.001). The overall assessment of the curriculum was positive (92.1 ± 8.5).

CONCLUSION

With our tailored curriculum, German paramedics were able to develop skills in POCUS comparable to those of other POCUS learners. Integration of POCUS into paramedics' training curricula offers opportunities and should be further studied.

Diagnostic accuracy of prehospital lung ultrasound for acute decompensated heart failure: A systematic review and Meta-analysis

BACKGROUND

Lung ultrasound (LUS) reduces time to diagnosis and treatment of acute decompensated heart failure (ADHF) in emergency department (ED) patients with undifferentiated dyspnea. We conducted a systematic review to evaluate the diagnostic accuracy and clinical impact of LUS for ADHF in the prehospital setting.

METHODS

We performed a keyword search of multiple databases from inception through June 1, 2023. Included studies were those enrolling prehospital patients with undifferentiated dyspnea or suspected ADHF, and specifically diagnostic studies comparing prehospital LUS to a gold standard and intervention studies with a non-US comparator group. Title and abstract screening, full text review, risk of bias (ROB) assessments, and data extraction were performed by multiple authors. and adjudicated. The primary outcome was pooled sensitivity, specificity, and diagnostic likelihood ratios (LR) for prehospital LUS. A test-treatment threshold of 0.7 was applied based on prior ADHF literature in the ED. Intervention outcomes included mortality, mechanical ventilation, and time to HF specific treatment.

RESULTS

Eight diagnostic studies (n = 691) and two intervention studies (n = 70) met inclusion criteria. No diagnostic studies were low-ROB. Both intervention studies were critical-ROB, and not pooled. Pooled sensitivity and specificity of prehospital LUS for ADHF were 86.7% (95%CI:70.8%-94.6%) and 87.5% (78.2%-93.2%), respectively, with similar performance by physician vs. paramedic LUS and number of lung zones evaluated. Pooled LR+ and LR- were 7.27 (95% CI: 3.69-13.10) and 0.17 (95% CI: 0.06-0.34), respectively. Area under the summary receiver operating characteristic curve was 0.922. At the observed 42.4% ADHF prevalence (pre-test probability), positive pre-hospital LUS exceeded the 70% threshold to initiate treatment (post-test probability 84%, 80-88%).

CONCLUSIONS

LUS had similar diagnostic test characteristics for ADHF diagnosis in the prehospital setting as in the ED. A positive prehospital LUS may be sufficient to initiate early ADHF treatment based on published test-treatment thresholds. More studies are needed to determine the clinical impact of prehospital LUS.

Prehospital lung ultrasound in acute heart failure: Impact on diagnosis and treatment

OBJECTIVE

Patients with acute heart failure (AHF) are commonly misdiagnosed and undertreated in the prehospital setting. These delays in diagnosis and treatment have a direct negative impact on patient outcomes. The goal of this study was to determine the diagnostic accuracy of paramedics with and without the use of lung ultrasound (LUS) for the diagnosis of AHF in patients with dyspnea in the prehospital setting. Secondarily, we assessed LUS impact on rate of and time to initiation of HF therapies.

METHODS

This was a prospective interventional study on a consecutive sample of patients transported to the hospital by one emergency medical services agency. Adult patients (>18 years) with a chief complaint of dyspnea were included. LUS was performed by trained paramedics and was defined as positive for AHF if both anterior-superior lung zones had greater than or equal to three B-lines or bilateral B-lines were visualized on a four-view protocol. Paramedic diagnosis was compared to hospital discharge diagnosis which served as the criterion standard.

RESULTS

Of the 264 included patients, 94 (35%) had a final diagnosis of AHF. Forty total patients had a LUS performed; 17 of these patients had a final diagnosis of AHF. Sensitivity and specificity for AHF by paramedics were 23% (95% confidence interval [CI] 0.14-0.34) and 97% (95% CI 0.92-0.99) without LUS and 71% (95% CI 0.44-0.88) and 96% (95% CI 0.76-0.99) with the use of LUS. In the 94 patients with AHF, 14% (11/77) received HF therapy prehospital without the use of LUS and 53% (9/17) with the use of LUS. LUS improved frequency of treatment by 39%. Median time to treatment was 21 min with LUS and 169 min without.

CONCLUSIONS

LUS improved paramedic sensitivity and accuracy for diagnosing AHF in the prehospital setting. LUS use led to higher rates of prehospital HF therapy initiation and significantly decreased time to treatment.

Ultrasound on the Frontlines: Empowering Paramedics with Lung Ultrasound for Dyspnea Diagnosis in Adults-A Pilot Study

Lung transthoracic ultrasound (LUS) is an accessible and widely applicable method of rapidly imaging certain pathologies in the thorax. LUS proves to be an optimal tool in respiratory emergency medicine, applicable in various clinical settings. However, despite the rapid development of bedside ultrasonography, or point-of-care (POCUS) ultrasound, there remains a scarcity of knowledge about the use of LUS in pre-hospital settings. Therefore, our aim was to assess the usefulness of LUS as an additional tool in diagnosing dyspnea when performed by experienced paramedics in real-life, pre-hospital settings. Participants were recruited consecutively among patients who called for an emergency due to dyspnea in the Warsaw region of Poland. All the enrolled patients were admitted to the Emergency Department (ED). In the prehospital setting, a paramedic experienced in LUS conducted an ultrasonographic examination of the thorax, including Bedside Lung Ultrasound in Emergency (BLUE) and extended Focused Assessment with Sonography for Trauma (eFAST) protocols. The paramedic's diagnosis was compared to the ED diagnosis, and if available, to the final diagnosis established on the day of discharge from the hospital. We enrolled 44 patients in the study, comprising 22 (50%) men and (50%) women with a median age of 76 (IQR: 69.75-84.5) years. The LUS performed by paramedic was concordant with the discharge diagnosis in 90.91% of cases, where the final diagnosis was established on the day of discharge from the hospital. In cases where the patient was treated only in the ED, the pre-hospital LUS was concordant with the ED diagnosis in 88.64% of cases. The mean time of the LUS examination was 63.66 s (SD: 19.22). The inter-rater agreement between the pre-hospital diagnosis and ER diagnosis based on pre-hospital LUS and complete ER evaluation was estimated at k = 0.822 (SE: 0.07; 95%CI: 0.68, 0.96), indicating strong agreement, and between the pre-hospital diagnosis based on LUS and final discharge diagnosis, it was estimated at k = 0.934 (SE: 0.03; 95%CI: 0.88, 0.99), indicating almost perfect agreement. In conclusion, paramedic-acquired LUS seems to be a useful tool in the pre-hospital differential diagnosis of dyspnea in adults.

Paramedic-Performed Prehospital Tele-Ultrasound: A Powerful Technology or an Impractical Endeavor? A Scoping Review

Ultrasound with remote assistance (tele-ultrasound) may have potential to improve accessibility of ultrasound for prehospital patients. A review of recent literature on this topic has not been done before, and the feasibility of prehospital tele-ultrasound performed by non-physician personnel is unclear. In an effort to address this, the literature was qualitatively analyzed from January 1, 2010 - December 31, 2021 in the MEDLINE, EMBASE, and Cochrane online databases on prehospital, paramedic-acquired tele-ultrasound, and ten articles were found. There was considerable heterogeneity in the study design, technologies used, and the amount of ultrasound training for the paramedics, preventing cross-comparisons of different studies. Tele-ultrasound has potential to improve ultrasound accessibility by leveraging skills of a remote ultrasound expert, but there are still technological barriers to overcome before determinations on feasibility can be made.

Review article: Prehospital telehealth for emergency care: A scoping review

Telehealth has been successfully implemented in the prehospital setting to expedite emergency care, although applications are still in their infancy. With recent advances in technologies, it is not described how prehospital telehealth has evolved over the past decade. This scoping review aimed to answer the research question 'what telehealth platforms have been used to facilitate communication between prehospital healthcare providers and emergency clinicians in the past decade?'. The review was guided by Joanna Briggs Institute scoping review methodology and reported in accordance with the PRISMA checklist for scoping reviews. A systematic search of five databases and Google Scholar was undertaken using key terms 'prehospital', 'ambulance', 'emergency care' and 'telehealth', and results were limited to research articles published in English language between 2011 and 2021. Articles were included if they related to the research question and reported quantitative, qualitative, mixed-method or feasibility studies. A total of 28 articles were included in the review that reported feasibility (n = 13), intervention (n = 7) or observational studies (n = 8) involving 20 telehealth platforms. Platforms were commonly implemented to provide prehospital staff with medical support for general emergency care and involved a range of devices that were used to transmit video, audio and biomedical data. The benefits of prehospital telehealth to patients, clinicians and organisations were identified. Challenges to telehealth involved technical, clinical and organisational issues. Few facilitators of prehospital telehealth were identified. Telehealth platforms to facilitate prehospital to ED communication continue to develop but require technological advances and improved network connectivity to support implementation in the prehospital environment.

Prehospital Ultrasound: A Narrative Review

Background: Point-of-care ultrasound is rapidly becoming more prevalent in the prehospital environment. Though considered a relatively new intervention in this setting, there is growing literature that aims to explore the use of prehospital ultrasound by EMS personnel.Methods: To better understand and report the state of the science on prehospital ultrasound, we conducted a narrative review of the literature.Results: Following a keyword search of MEDLINE in Ovid from inception to August 2, 2022, 2,564 records were identified and screened. Based on review of abstracts and full texts, with addition of seven articles via bibliography review, 193 records were included. Many included studies detail usage in air medical and other critical care transport environments. Clinicians performing prehospital ultrasound are often physicians or other advanced practice personnel who have previous ultrasound experience, which facilitates implementation in the prehospital setting. Emerging literature details training programs for prehospital personnel who are novices to ultrasound, and implementation for some study types appears feasible without prior experience. Unique use scenarios that show promise include during critical care transport, for triage in austere settings, and for thoracic evaluation of patients at risk of life-threatening pathology.Conclusion: There is a growing mostly observational body of literature describing the use of ultrasound by prehospital personnel. Prehospital ultrasound has demonstrated feasibility for specific conditions, yet interventional studies evaluating benefit to patient outcomes are absent.

Small Animal Teleultrasound

Teleradiology is well established in many small animal practices, whereas teleultrasound is slowly gaining prominence. The demand for teleultrasound services in the veterinary profession has increased substantially because access to ultrasound to general practitioners increases faster than the number of imaging specialists and Point of Care Ultrasound (POCUS) becomes part of the standard of care. Two main methods of teleultrasound currently exist: asynchronous (eg, "store-and-forward") and synchronous (eg, real-time) interpretations. Few standardized protocols for teleultrasound in small animals are available. Similarly, there are no standardized training programs for sonographic examination acquisition and interpretation outside of the traditional diagnostic imaging residency under the purview of the American College of Veterinary Radiology. The success of a telesonographic evaluation largely depends on the relationship between the veterinarian requesting remote assistance and the expert providing support.

Use of Point-of-Care Ultrasound by Intensive Care Paramedics to Assess Respiratory Distress in the Out-of-Hospital Environment: A Pilot Study

BACKGROUND

Respiratory distress is a common presentation attended by paramedics. Chest auscultation has been shown to have low accuracy for diagnosing respiratory complaints, and this can lead to inaccurate patient assessment and potentially poor patient outcomes. Conversely, lung ultrasound is a relatively simple exam allowing for rapid differentiation of respiratory complaints with comparable accuracy to more advanced imaging modalities. Evidence suggests that lung ultrasound is easy to learn and apply and could be ideal for assessment of respiratory illness by paramedics.

OBJECTIVE

This study aimed to explore the utility of out-of-hospital lung ultrasound performed by intensive care paramedics (ICP) for patients with medical causes of respiratory distress, and explore whether the use of lung ultrasound affects the ICP's clinical impression or management.

METHODS

This was a prospective observational pilot study. After a training program, a sample of ICPs working in metropolitan and regional Victoria, Australia used ultrasound to assess adult patients with respiratory distress and/or dyspnea. ICPs used a handheld point-of-care ultrasound device to scan respiratory patients using a modified protocol, and completed a worksheet with their scan findings. The scans were then reviewed by a subject matter expert for quality and agreement.

RESULTS

Ninety-five patients were enrolled over the study period. The average image quality score was 2.68/5, and 56% of scans were of interpretable quality. Interrater agreement (between the ICPs and the subject matter expert) was reported using Cohen's kappa. Moderate overall agreement (0.44) was shown, with the highest reliability reported in A-profile and B-profile (0.49 and 0.57). In 42% of cases performance of the scan affected paramedic clinical impression and/or management.

CONCLUSION

ICPs can perform lung ultrasound with moderate accuracy for some respiratory conditions, and the scans may affect clinical impression and management. Future research should focus on enhanced education, expert feedback, and clinical outcomes.

Use of Point-of-Care Ultrasound by Non-Physicians to Assess Respiratory Distress in the Out-of-Hospital Environment: A Scoping Review

BACKGROUND

The use of ultrasound in the out-of-hospital environment is increasingly feasible. The potential uses for point-of-care ultrasound (POCUS) by paramedics are many, but have historically been limited to traumatic indications. This study utilized a scoping review methodology to map the evidence for the use of POCUS by paramedics to assess respiratory distress and to gain a broader understanding of the topic.

METHODS

Databases Ovid MEDLINE, EMBASE, CINAHL Plus, and PUBMED were searched from January 1, 1990 through April 14, 2021. Google Scholar was searched, and reference lists of relevant papers were examined to identify additional studies. Articles were included if they reported on out-of-hospital POCUS performed by non-physicians for non-traumatic respiratory distress.

RESULTS

A total of 591 unique articles were identified, of which seven articles met the inclusion criteria. The articles reported various different scan protocols and, with one exception, suffered from low enrolments and low participation. Most articles reported that non-physician-performed ultrasound was feasible. Articles reported moderate to high levels of agreement between paramedics and expert reviewers for scan interpretation in most studies.

CONCLUSION

Paramedics and emergency medical technicians (EMTs) have demonstrated the feasibility of lung ultrasound in the out-of-hospital environment. Further research should investigate the utility of standardized education and scanning protocols in paramedic-performed lung ultrasound for the differentiation of respiratory distress and the implications for patient outcomes.

The Utilization of Handheld Ultrasound Devices in a Prehospital Setting

INTRODUCTION

Prehospital ultrasounds can be considered a new form of diagnostic tool when taking into account their small structure and due to the fact that nowadays, they are used in the care of emergency patients. However, at present, there is no study regarding the advantage of ultrasound usage in prehospital settings in Thailand.

STUDY OBJECTIVE

This study aims to determine the sonographic characteristics recorded by handheld ultrasounds used in prehospital care and the diagnostic accuracy of ultrasounds for prehospital patients.

METHODS

A cross-sectional study was conducted on prehospital patients who underwent point-of-care ultrasound (POCUS) examination on Emergency Medical Service (EMS) operations at Srinagarind Hospital, Thailand from January 2021 through December 2021. The ultrasound images, the electronic emergency department medical records, and the EMS database were recorded and reviewed by a team of emergency physicians. The quality of prehospital ultrasound examinations was assessed by comparing the diagnoses at the scene with those taken at the hospital.

RESULTS

One hundred sixty-nine prehospital patients who received POCUS examinations were examined over a one-year period. All (100.0%) of the scans were for medical cases. No ultrasound protocol was used in the prehospital care. Two hundred eight POCUS examinations were performed in this study. The most common POCUS indication was dyspnea (45.6%), followed by hypotension/shock (30.1%), and finally syncope (8.2%). The most common area where POCUS was performed was on the lung (37.0%), followed by the inferior vena cava (30.8%), and finally for cardiac cases (26.4%). This study found that 34.9% of sonographic findings could be considered abnormal. The diagnoses of prehospital patients were confirmed by using POCUS in 66 cases (39.1%) with the accuracy of prehospital diagnosis reaching a peak of 75.8%.

CONCLUSION

This study shows POCUS examinations can be effectively used in prehospital care. The prehospital diagnosis given by physicians administering treatment who used POCUS examinations correlated with the in-hospital diagnosis.

Flight Teams' Learning Needs Assessment on Ultrasound: A Mixed Methods Approach

OBJECTIVE

The goal of this study was to understand flight clinicians' learning needs and attitudes with regard to a prehospital ultrasound curriculum.

METHODS

In this convergent mixed methods study, 21 prehospital clinicians completed a questionnaire, and 20 attended a 1-hour focus group to explore attitudes regarding learning ultrasound. These participants were from a single emergency medical service agency.

RESULTS

Five themes emerged from the focus group transcripts and were supported by the quantitative data: 1) theme 1, hands-on training in ultrasound is a highly preferred modality; 2) theme 2, emergency medical service providers desire learning integrated into shifts and real-life practice; 3) theme 3, prehospital providers express concerns about training and maintenance of competency; 4) theme 4, participants recognize the need for quality control during the training phase and after; and 5) theme 5, participants were enthusiastic about how ultrasound could help guide clinical decision making and potentially improve patient outcomes.

CONCLUSION

Those who participated in an evidence-based assessment of prehospital ultrasound needs and barriers were experienced flight clinicians who would use prehospital ultrasound if made available. These adult learners indicated their preferred learning method would be using standardized patients, simulators, and hands-on in the field with physicians. They preferred follow-up courses and simulators to maintain competency.

A National Survey of Prehospital Care Services of United Kingdom for Use, Governance and Perception of Prehospital Point of Care Ultrasound

Introduction: Point of care ultrasound (POCUS) has become a common practice in prehospital care over the last 10 years. There is lack of literature on its use and governance structure in United Kingdom (UK) prehospital care services. We aimed to survey the use, governance of prehospital POCUS among UK prehospital services and perceptions of clinicians and services regarding its utility and barriers to its implementation. Methods: Four electronic questionnaire surveys were delivered to UK helicopter emergency medical service (HEMS) & clinicians, ambulance and community emergency medicine (CEM) services between 1^st of April and 31^st of July 2021 investigating current use, governance structure for POCUS and perception about its benefits and barriers. Invitations were sent via email to medical directors or research leads of services and using social media. Survey links remained live for two months each. Results: Overall, 90%, 62% and 60% of UK HEMS, ambulance and CEM services respectively, responded to surveys. Most of the services used prehospital POCUS, however only two HEMS organisations fulfilled the Royal College of Radiology governance criteria for POCUS. The most commonly performed POCUS modality was echo in cardiac arrest. Majority of clinicians judged POCUS to be beneficial and the common perceived benefit was promotion of enhanced and effective clinical care. Major barriers to its implementation included a lack of formal governance, limited literature supporting its use and difficulties in performing POCUS in prehospital environment. Conclusion: This survey demonstrates that prehospital POCUS is being provided by a majority of the prehospital care services and clinicians have found it beneficial in providing enhanced clinical care to their patients. However, the barriers to its implementation are relative lack of governance structure and supportive literature.

Helicopter emergency medical services use of thoracic point of care ultrasound for pneumothorax: a systematic review and meta-analysis

Background

Auscultating for breath sounds to assess for pneumothorax in the helicopter emergency medical services (HEMS) settings can be extremely challenging. Thoracic point of care ultrasound (POCUS) offers a seemingly more useful visual (rather than audible) alternative. This review critically and quantitatively evaluates the use of thoracic POCUS for pneumothorax in the HEMS setting.

Methods

A systematic literature review with meta-analysis was conducted. Only papers reporting on patients undergoing POCUS for pneumothorax in the helicopter or pre-hospital setting were included. Primary outcome was accuracy, focusing on sensitivity and specificity. Secondary outcome was practicality. PubMed, Embase and the Cochrane Library were searched. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) was used to assess validity of studies.

Results

Twelve studies reporting on n = 1,936 images from medical and trauma patients were included in qualitative synthesis. Studies were nearly all observational designs. Most images were acquired by nurses or paramedics who were previously novices to ultrasound. The reference standard was predominantly CT. Specificity results were unanimously precise and very high, whereas sensitivity results were imprecise and extremely variable. Meta-analysis of eight studies involving n = 1,713 images yielded pooled sensitivity 61% (95% CI: 27–87%; I² = 94%) and pooled specificity 99% (95% CI: 98–100%; I² = 89%). Six studies involving n = 315 images reported practicality. The highest or second highest categorisation of image quality was reported in around half of those images.

Conclusion

Thoracic POCUS is highly specific but has extremely variable sensitivity for pneumothorax when performed in the HEMS setting. This is from purely a diagnostic (not clinical) perspective. Sensitivity increases when only clinically significant pneumothoraces are considered. Case reports reveal thoracic POCUS can appropriately alter treatment and triage decisions, but only for a small number of patients. It appears predominantly useful in mitigating against unnecessary interventions. More research reporting patient focused outcomes is required. In the meantime, thoracic POCUS appears to offer a more appropriate visual alternative to auscultation for breath sounds when assessing for pneumothorax in the HEMS setting.

Paramedic-performed Prehospital Point-of-care Ultrasound for Patients with Undifferentiated Dyspnea: A Pilot Study

INTRODUCTION

Thoracic ultrasound is frequently used in the emergency department (ED) to determine the etiology of dyspnea, yet its use is not widespread in the prehospital setting. We sought to investigate the feasibility and diagnostic performance of paramedic acquisition and assessment of thoracic ultrasound images in the prehospital environment, specifically for the detection of B-lines in congestive heart failure (CHF).

METHODS

This was a prospective observational study of a convenience sample of adult patients with a chief complaint of dyspnea. Paramedics participated in a didactic and hands-on session instructing them how to use a portable ultrasound device. Paramedics assessed patients for the presence of B-lines. Sensitivity and specificity for the presence of bilateral B-lines and any B-lines were calculated based on discharge diagnosis. Clips archived to the ultrasound units were reviewed and paramedic interpretations were compared to expert sonologist interpretations.

RESULTS

A total of 63 paramedics completed both didactic and hands-on training, and 22 performed ultrasounds in the field. There were 65 patients with B-line findings recorded and a discharge diagnosis for analysis. The presence of bilateral B-lines for diagnosis of CHF yielded a sensitivity of 80.0% (95% confidence interval [CI], 51.4-94.7%) and specificity of 72.0% (95% CI, 57.3-83.3), while presence of any B-lines was 93.3% sensitive (95% CI, 66.0-99.7%), and 50% specific (95% CI, 35.7-64.2%) for CHF. Paramedics archived 117 ultrasound clips of which 63% were determined to be adequate for interpretation. Comparison of paramedic and expert sonologist interpretation of images showed good inter-rater agreement for detection of any B-lines (k = 0.60; 95% CI, 0.36-0.84).

CONCLUSION

This observational pilot study suggests that prehospital lung ultrasound for B-lines may aid in identifying or excluding CHF as a cause of dyspnea. The presence of bilateral B-lines as determined by paramedics is reasonably sensitive and specific for the diagnosis of CHF and pulmonary edema, while the absence of B lines is likely to exclude significant decompensated heart failure. The study was limited by being a convenience sample and highlighted some of the difficulties related to prehospital research. Larger funded trials will be needed to provide more definitive data.

Quality of focused thoracic ultrasound performed by emergency medical technicians and paramedics in a prehospital setting: a feasibility study

BACKGROUND

In a prehospital setting, the severity of respiratory symptoms in patients calling for an ambulance differ. The initial evaluation, diagnosing, and thereby management can be challenging because respiratory symptoms can be caused by disease in many organs. Ultrasound examinations can contribute with important information and support the clinical decision-making. However, ultrasound is user-dependent and requires sufficient knowledge and training. The aim of this study was to explore the quality of thoracic ultrasound examinations performed on patients by emergency medical technicians and paramedics in a prehospital, clinical setting.

METHODS

From November 2018 - April 2020, Danish emergency medical technicians and paramedics (n = 100) performed thoracic ultrasound examinations on patients with respiratory symptoms using a portable ultrasound device. The ultrasound examinations were stored and retrospectively assessed by a reviewer blinded to the patients' symptoms and history, as well as the emergency medical technicians' and paramedics' findings. The image quality was scored from 1 to 5. The findings determined by the reviewer was then correlated with a questionnaire filled out by the emergency medical technicians and paramedics regarding ultrasonic findings and potential change in treatment or management of the patient. The agreement in percentage and as Cohen's kappa was explored.

RESULTS

A total of 590 ultrasound examinations were assessed, resulting in a median image quality score of 3 (IQ1 = 4, IQ3 = 3). The overall agreement in percentage between the emergency medical technicians and paramedics and 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). Cohen's kappa varied from 0.01 for possible pneumothorax to 0.69 for pleural effusion. Based on the questionnaires (n = 406), the ultrasound examination entailed a change in treatment or visitation in 48 cases (11.7%) which in this study population encompasses a number-needed-to-scan of 8.5.

CONCLUSION

Emergency medical technicians and paramedics perform focused thoracic ultrasound examinations with adequate image quality sufficient to determine if pathology is present or not. The emergency medical technicians' and paramedics' assessment correlates to some extent with an experienced reviewer and their findings are most reliable for the inclusion of a normal scan or inclusion of pleural effusion. Implementation could possibly impact the number of patients receiving correct prehospital treatment and optimal choice of receiving facility.

Lung ultrasound in the diagnosis of COVID-19 infection - A case series and review of the literature

COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and spreading worldwide has become a serious challenge for the entire health care system as regards infection prevention, rapid diagnosis, and treatment. Lung ultrasound (LUS) is a dynamically developing diagnostic method used in intensive care, cardiology and nephrology, it can also be helpful in diagnosing and monitoring pneumonia. Interstitial pneumonia appears to be the most common clinical manifestation of coronavirus infection. We present 4 case reports of COVID-19 involving the lungs, in which transthoracic lung ultrasound was successfully utilized as a constituent of bedside diagnostics and a review of the literature concerning potential use of LUS in COVID-19 diagnostics. The possibility to perform this examination repeatedly, its non-invasiveness and high sensitivity make it an important element of care provided for patients with viral pneumonia.

Prehospital point-of-care ultrasound: A transformative technology

Point-of-care ultrasound at the bedside has evolved into an essential component of emergency patient care. Current evidence supports its use across a wide spectrum of medical and traumatic diseases in a variety of settings. The prehospital use of ultrasound has evolved from a niche technology to impending widespread adoption across emergency medical services systems internationally. Recent technological advances and a growing evidence base support this trend. However, concerns regarding feasibility, education, and quality assurance must be addressed proactively. This topical review describes the history of prehospital ultrasound, initial training needs, ongoing skill maintenance, quality assurance and improvement requirements, available devices, and indications for prehospital ultrasound.

Inferior Vena Cava Diameter is an Early Marker of Central Hypovolemia during Simulated Blood Loss

INTRODUCTION

Inferior vena cava (IVC) diameter decreases under conditions of hypovolemia. Point-of-care ultrasound (POCUS) may be useful to emergently assess IVC diameter. This study tested the hypothesis that ultrasound measurements of IVC diameter decreases during severe simulated blood loss.

METHODS

Blood loss was simulated in 14 healthy men (22 ± 2 years) using lower body negative pressure (LBNP). Pressure within the LBNP chamber was reduced 10 mmHg of LBNP every four minutes until participants experienced pre-syncopal symptoms or until 80 mmHg of LBNP was completed. IVC diameter was imaged with POCUS using B-mode in the long and short axis views between minutes two and four of each stage.

RESULTS

Maximum IVC diameter in the long axis view was lower than baseline (1.5 ± 0.4 cm) starting at -20 mmHg of LBNP (1.0 ± 0.3 cm; p < 0.01) and throughout LBNP (p < 0.01). The minimum IVC diameter in the long axis view was lower than baseline (0.9 ± 0.3 cm) at -20 mmHg of LBNP (0.5 ± 0.3 cm; p < 0.01) and throughout LBNP (p < 0.01). Maximum IVC diameter in the short axis view was lower than baseline (0.9 ± 0.2 cm) at 40 mmHg of LBNP (0.6 ± 0.2; p = 0.01) and the final LBNP stage (0.6 ± 0.2 cm; p < 0.01). IVC minimum diameter in the short axis view was lower than baseline (0.5 ± 0.2 cm) at the final LBNP stage (0.3 ± 0.2 cm; p = 0.01).

CONCLUSION

These data demonstrate that IVC diameter decreases prior to changes in traditional vital signs during simulated blood loss. Further study is needed to determine the view and diameter threshold that most accurate for identifying hemorrhage requiring emergent intervention.

A Blended Prehospital Ultrasound Curriculum for Critical Care Paramedics

OBJECTIVE

Point-of-care ultrasound is a nascent and growing area of prehospital care. Most previously described ultrasound curricula for paramedics examine a single type of ultrasound scan. Here, we describe the implementation and evaluation of a prehospital ultrasound curriculum using a blended model of traditional didactics and hands-on experience with online prereading.

METHODS

We recruited a prospective convenience sample of critical care paramedics without prior ultrasound experience to take part in a 2-day ultrasound course. All participants completed prereading modules built from online resources followed by a didactic review of the material and hands-on practice. Ultrasound examinations included extended focused abdominal sonography in trauma, cardiac ultrasound, thoracic ultrasound, and vascular ultrasound. A written examination evaluated ultrasound theory and image interpretation, and a practical examination evaluated image acquisition.

RESULTS

Seventeen critical care paramedics completed the course with a mean grade on the written examination of 76%, with 76% of paramedics achieving the predetermined passing mark of 70% or greater. All paramedics passed the practical examination.

CONCLUSION

The implementation of a prehospital critical care ultrasound program is feasible in our provincial emergency medical services system. Further assessment is necessary to determine future knowledge and skill retention as well as clinical application and utility in real-world settings.

Ability of non-physicians to perform and interpret lung ultrasound: A systematic review

BACKGROUND

Lung ultrasound is a useful tool in the assessment of pulmonary congestion in heart failure that is typically performed and interpreted by physicians at the point-of-care.

AIMS

To investigate the ability of nurses, students, and paramedics to accurately identify B-lines and pleural effusions for the detection of pulmonary congestion in heart failure and to examine the training necessary.

METHODS AND RESULTS

We conducted a systematic review and searched online databases for studies that investigated the ability of nurses, students, and paramedics to perform lung ultrasound and detect B-lines and pleural effusions. Of 979 studies identified, 14 met our inclusion criteria: five in nurses, eight in students, and one in paramedics. After 0-12 h of didactic training and 58-62 practice lung ultrasound examinations, nurses were able to identify B-lines and pleural effusions with a sensitivity of 79-98% and a specificity of 70-99%. In image adequacy studies, medical students with 2-9 h of training were able to acquire adequate images for B-lines and pleural effusions in 50-100%. Only one eligible study investigated paramedic-performed lung ultrasound which did not support the ability of paramedics to adequately acquire and interpret lung ultrasound images after 2 h of training.

CONCLUSIONS

Our findings suggest that nurses and students can accurately acquire and interpret lung ultrasound images after a brief training period in a majority of cases. The examination of heart failure patients with lung ultrasound by non-clinicians appears feasible and warrants further investigation.

Paramedic point of care ultrasound at Australian mass gatherings

Point of care ultrasound (POCUS) is not traditionally performed by paramedics, and where it is used, is generally limited to resuscitative-type ultrasound examinations. We describe a select series of patient care cases collected between August 2017 and February 2018 which are the first known examples of expanded POCUS performed by a paramedic in this context. These point of care scans were performed for both high and lower acuity patient presentations and are felt to have contributed to improved decision-making in the treatment and onward referral of patients in the Australian festival and event medicine.

Usefulness of point-of-care ultrasound in military medical emergencies performed by young military medicine residents

INTRODUCTION

To evaluate the usefulness of point-of-care ultrasound (POCUS) performed by young military medicine residents after short training in the diagnosis of medical emergencies.

METHODS

A prospective study was performed in the emergency department of a French army teaching hospital. Two young military medicine residents received ultrasound training focused on gall bladder, kidneys and lower limb veins. After clinical examination, they assigned a 'clinical diagnostic probability' (CP) on a visual analogue scale from 0 (definitely not diagnosis) to 10 (definitive diagnosis). The same student performed ultrasound examination and assigned an 'ultrasound diagnostic probability' (UP) in the same way. The absolute difference between CP and UP was calculated. This result corresponded to the Ultrasound Diagnostic Index (UDI), which was positive if UP was closer to the final diagnosis than CP (POCUS improved the diagnostic accuracy), and negative conversely (POCUS decreased the diagnostic accuracy).

RESULTS

Forty-eight patients were included and 48 ultrasound examinations were performed. The present pathologies were found in 14 patients (29%). The mean UDI value was +3 (0-5). UDI was positive in 35 exams (73%), zero in 12 exams (25%) and negative in only one exam (2%).

CONCLUSION

POCUS performed after clinical examination increases the diagnostic accuracy of young military medicine residents.

Feasibility of Out-of-Hospital Cardiac Arrest Ultrasound by EMS Physicians

INTRODUCTION

Point-of-care ultrasound (POCUS) has been suggested as a useful tool to predict survival and guide interventions in out-of-hospital cardiac arrest (OHCA). While POCUS has been deployed in prehospital settings, a minimal amount of data exists on prehospital use, particularly by personnel with limited ultrasound experience. We aimed to characterize the feasibility and barriers to prehospital POCUS during OHCA by emergency medicine services (EMS) physicians in training.

METHODS

We deployed the SonoSite iViz portable ultrasound device for use by EMS physicians for OHCA in an urban EMS system. All physicians received POCUS education as part of their graduate medical training and were provided an instructional video on use of the SonoSite iViz device. POCUS use was limited to identifying cardiac motion during pulse checks, without interrupting resuscitation, and the results could be used to supplement management at the physicians' discretion. Data were recorded prospectively by saving images on the device and through a custom electronic form within the patient care report. The primary measure was the frequency of use of POCUS during OHCA. Secondarily, we characterized agreement by expert (ultrasound fellowship trained) faculty (using a kappa statistic) and identified reported barriers to the use of prehospital POCUS.

RESULTS

From November 2016 to March 2017, 348 physician field responses were reviewed, including 127 cases of OHCA. There were 106 patients remaining in arrest on physician arrival, with 56 (52.8%) cases of POCUS use. Still or video images were recorded in 48 cases; video in 34 cases. From video images, agreement in identifying cardiac motion between the EMS physician and expert reviewer occurred in 91% of cases (K = 0.82). Reasons cited for not using POCUS included return of circulation soon before or after arrival, prioritizing clinical interventions, not having the ultrasound device, mechanical failure, and cessation of resuscitation per advanced directives.

CONCLUSION

Use of POCUS by EMS physicians to detect cardiac activity in OHCA is feasible and correlates with expert interpretation. Several avoidable barriers were identified and should be considered in the future implementation of prehospital POCUS. Larger studies are needed to determine what role POCUS may play in prehospital cardiac arrest management.