Prehospital ultrasound by paramedics: results of field trial

Image-based resuscitation of the hypotensive patient with cardiac ultrasound: An evidence-based review

This article is a detailed review of the literature regarding the use of cardiac ultrasound for the resuscitation of hypotensive patients. In addition, figures regarding windows and description of how to perform the test are included.

Pre-hospital assessment with ultrasound in emergencies: implementation in the field

BACKGROUND

Point-of-care ultrasound (US) is a proven diagnostic imaging tool in the emergency department (ED). Modern US devices are now more compact, affordable and portable, which has led to increased usage in austere environments. However, studies supporting the use of US in the prehospital setting are limited. The primary outcome of this pilot study was to determine if paramedics could perform cardiac ultrasound in the field and obtain images that were adequate for interpretation. A secondary outcome was whether paramedics could correctly identify cardiac activity or the lack thereof in cardiac arrest patients.

METHODS

We performed a prospective educational study using a convenience sample of professional paramedics without ultrasound experience. Eligible paramedics participated in a 3-hour session on point-of-care US. The paramedics then used US during emergency calls and saved the scans for possible cardiac complaints including: chest pain, dyspnea, loss of consciousness, trauma, or cardiac arrest.

RESULTS

Four paramedics from two distinct fire stations enrolled a total of 19 unique patients, of whom 17 were deemed adequate for clinical decision making (89%, 95%CI 67%-99%). Paramedics accurately recorded 17 cases of cardiac activity (100%, 95%CI 84%-100%) and 2 cases of cardiac standstill (100%, 95%CI 22%-100%).

CONCLUSION

Our pilot study suggests that with minimal training, paramedics can use US to obtain cardiac images that are adequate for interpretation and diagnose cardiac standstill. Further large-scale clinical trials are needed to determine if prehospital US can be used to guide care for patients with cardiac complaints.

Point-of-care ultrasonography by pediatric emergency physicians. Policy statement

Point-of-care ultrasonography is increasingly being used to facilitate accurate and timely diagnoses and to guide procedures. It is important for pediatric emergency physicians caring for patients in the emergency department to receive adequate and continued point-of-care ultrasonography training for those indications used in their practice setting. Emergency departments should have credentialing and quality assurance programs. Pediatric emergency medicine fellowships should provide appropriate training to physician trainees. Hospitals should provide privileges to physicians who demonstrate competency in point-of-care ultrasonography. Ongoing research will provide the necessary measures to define the optimal training and competency assessment standards. Requirements for credentialing and hospital privileges will vary and will be specific to individual departments and hospitals. As more physicians are trained and more research is completed, there should be one national standard for credentialing and privileging in point-of-care ultrasonography for pediatric emergency physicians.

Prehospital Evaluation of Effusion, Pneumothorax, and Standstill (PEEPS): Point-of-care Ultrasound in Emergency Medical Services

Introduction

In the United States, there are limited studies regarding use of prehospital ultrasound (US) by emergency medical service (EMS) providers. Field diagnosis of life-threatening conditions using US could be of great utility. This study assesses the ability of EMS providers and students to accurately interpret heart and lung US images.

Methods

We tested certified emergency medical technicians (EMT-B) and paramedics (EMT-P) as well as EMT-B and EMT-P students enrolled in prehospital training programs within two California counties. Participants completed a pre-test of sonographic imaging of normal findings and three pathologic findings: pericardial effusion, pneumothorax, and cardiac standstill. A focused one-hour lecture on emergency US imaging followed. Post-tests were given to all EMS providers immediately following the lecture and to a subgroup one week later.

Results

We enrolled 57 prehospital providers (19 EMT-B students, 16 EMT-P students, 18 certified EMT-B, and 4 certified EMT-P). The mean pre-test score was 65.2%±12.7% with mean immediate post-test score of 91.1%±7.9% (95% CI [22%–30%], p<0.001). Scores significantly improved for all three pathologic findings. Nineteen subjects took the one-week post-test. Their mean score remained significantly higher: pre-test 65.8%±10.7%; immediate post-test 90.5%±7.0% (95% CI [19%–31%], p<0.001), one-week post-test 93.1%±8.3% (95% CI [21%–34%], p<0.001).

Conclusion

Using a small sample of EMS providers and students, this study shows the potential feasibility for educating prehospital providers to accurately identify images of pericardial effusion, pneumothorax, and cardiac standstill after a focused lecture.

Point-of-care ultrasound education for non-physician clinicians in a resource-limited emergency department

OBJECTIVE

To describe the outcomes and curriculum components of an educational programme to train non-physician clinicians working in a rural, Ugandan emergency department in the use of POC ultrasound.

METHODS

The use of point-of-care ultrasound was taught to emergency care providers through lectures, bedsides teaching and hands-on practical sessions. Lectures were tailored to care providers' knowledge base and available therapeutic means. Every ultrasound examination performed by these providers was recorded over 4.5 years. Findings of these examinations were categorised as positive, negative, indeterminate or procedural. Other radiologic studies ordered over this same time period were also recorded.

RESULTS

A total of 22,639 patients were evaluated in the emergency department by emergency care providers, and 2185 point-of-care ultrasound examinations were performed on 1886 patients. Most commonly used were the focused assessment with sonography in trauma examination (53.3%) and echocardiography (16.4%). Point-of-care ultrasound studies were performed more frequently than radiology department-performed studies. Positive findings were documented in 46% of all examinations.

CONCLUSIONS

We describe a novel curriculum for point-of-care ultrasound education of non-physician emergency practitioners in a resource-limited setting. These non-physician clinicians integrated ultrasound into clinical practice and utilised this imaging modality more frequently than traditional radiology department imaging with a large proportion of positive findings.

Disaster response team FAST skills training with a portable ultrasound simulator compared to traditional training: pilot study

Introduction

Pre-hospital focused assessment with sonography in trauma (FAST) has been effectively used to improve patient care in multiple mass casualty events throughout the world. Although requisite FAST knowledge may now be learned remotely by disaster response team members, traditional live instructor and model hands-on FAST skills training remains logistically challenging. The objective of this pilot study was to compare the effectiveness of a novel portable ultrasound (US) simulator with traditional FAST skills training for a deployed mixed provider disaster response team.

Methods

We randomized participants into one of three training groups stratified by provider role: Group A. Traditional Skills Training, Group B. US Simulator Skills Training, and Group C. Traditional Skills Training Plus US Simulator Skills Training. After skills training, we measured participants’ FAST image acquisition and interpretation skills using a standardized direct observation tool (SDOT) with healthy models and review of FAST patient images. Pre- and post-course US and FAST knowledge were also assessed using a previously validated multiple-choice evaluation. We used the ANOVA procedure to determine the statistical significance of differences between the means of each group’s skills scores. Paired sample t-tests were used to determine the statistical significance of pre- and post-course mean knowledge scores within groups.

Results

We enrolled 36 participants, 12 randomized to each training group. Randomization resulted in similar distribution of participants between training groups with respect to provider role, age, sex, and prior US training. For the FAST SDOT image acquisition and interpretation mean skills scores, there was no statistically significant difference between training groups. For US and FAST mean knowledge scores, there was a statistically significant improvement between pre- and post-course scores within each group, but again there was not a statistically significant difference between training groups.

Conclusion

This pilot study of a deployed mixed-provider disaster response team suggests that a novel portable US simulator may provide equivalent skills training in comparison to traditional live instructor and model training. Further studies with a larger sample size and other measures of short- and long-term clinical performance are warranted.

International evidence-based recommendations for focused cardiac ultrasound

BACKGROUND

Focused cardiac ultrasound (FoCUS) is a simplified, clinician-performed application of echocardiography that is rapidly expanding in use, especially in emergency and critical care medicine. Performed by appropriately trained clinicians, typically not cardiologists, FoCUS ascertains the essential information needed in critical scenarios for time-sensitive clinical decision making. A need exists for quality evidence-based review and clinical recommendations on its use.

METHODS

The World Interactive Network Focused on Critical UltraSound conducted an international, multispecialty, evidence-based, methodologically rigorous consensus process on FoCUS. Thirty-three experts from 16 countries were involved. A systematic multiple-database, double-track literature search (January 1980 to September 2013) was performed. The Grading of Recommendation, Assessment, Development and Evaluation method was used to determine the quality of available evidence and subsequent development of the recommendations. Evidence-based panel judgment and consensus was collected and analyzed by means of the RAND appropriateness method.

RESULTS

During four conferences (in New Delhi, Milan, Boston, and Barcelona), 108 statements were elaborated and discussed. Face-to-face debates were held in two rounds using the modified Delphi technique. Disagreement occurred for 10 statements. Weak or conditional recommendations were made for two statements and strong or very strong recommendations for 96. These recommendations delineate the nature, applications, technique, potential benefits, clinical integration, education, and certification principles for FoCUS, both for adults and pediatric patients.

CONCLUSIONS

This document presents the results of the first International Conference on FoCUS. For the first time, evidence-based clinical recommendations comprehensively address this branch of point-of-care ultrasound, providing a framework for FoCUS to standardize its application in different clinical settings around the world.

Out of hospital point of care ultrasound: current use models and future directions

INTRODUCTION

Ultrasound has evolved from a modality that was once exclusively reserved to certain specialities of its current state, in which its portability and durability lend to its broadly increasing applications.

OBJECTIVES

This review describes portable ultrasound in the hospital setting and its comparison to gold standard imaging modalities. Also, this review summarizes current literature describing portable ultrasound use in prehospital, austere and remote environments, highlighting successes and barriers to use in these environments.

DISCUSSION

Prehospital ultrasound has the ability to increase diagnostic ability and allow for therapeutic intervention in the field. In austere environments, ultrasound may be the only available imaging modality and thus can guide diagnosis, therapeutics and determine which patients may need emergent transfer to a healthcare facility. The most cutting edge applications of portable ultrasound employ telemedicine to obtain and transmit ultrasound images. This technology and ability to transmit images via satellite and cellular transmission can allow for even novice users to obtain interpretable images in austere environments. Portable ultrasound uses have steadily grown and will continue to do so with the introduction of more portable and durable technologies. As applications continue to grow, certain technologic considerations and future directions are explored.

The bubble study: ultrasound confirmation of central venous catheter placement

STUDY OBJECTIVE

The objective was to determine if ultrasound (US) can more rapidly confirm central venous catheter (CVC) position in comparison to chest radiography (CXR) in the emergency department.

METHODS

The study included a convenience sample of emergency department patients with supradiaphragmatic CVCs and a CXR for confirmation. Ultrasound was used for CVC confirmation by visualizing microbubble artifact in the right atrium after injection of saline through the distal port. To evaluate for pneumothorax (PTX), "sliding sign" of the pleura was noted on US of the anterior chest. Blinded chart review was performed to assess CXR timing, catheter position and CVC complications. Student's t test was used to compare US time to CXR performance time and radiologist reading time.

RESULTS

Fifty patients were enrolled; 4 were excluded because of inadequate views. Forty-six patients were included in the final analysis. Mean total US time was 5.0 minutes (95% confidence interval [CI], 4.2-5.9) compared to 28.2 minutes (95% CI, 16.8-39.4) for CXR performance with a mean difference of 23.1 minutes (95% CI, -34.5 to -11.8; P < .0002). When comparing only US CVC confirmation time to CXR time, US was an average of 24.0 minutes (95% CI, -35.4 to -12.7; P < .0001) faster. Comparing total US time to radiologist CXR reading time, US was an average of 294 minutes faster (95% CI, -384.5 to -203.5; P < .0000). There were a total of 3 misplaced lines and 2 patients with PTX, all of which were identified correctly on US.

CONCLUSION

Ultrasound can confirm CVC placement and rule out PTX significantly faster than CXR, expediting the use of CVCs in the critically ill.

Prospective evaluation of prehospital trauma ultrasound during aeromedical transport

BACKGROUND

Ultrasound is widely considered the initial diagnostic imaging modality for trauma. Preliminary studies have explored the use of trauma ultrasound in the prehospital setting, but the accuracy and potential utility is not well understood.

OBJECTIVE

We sought to determine the accuracy of trauma ultrasound performed by helicopter emergency medical service (HEMS) providers.

METHODS

Trauma ultrasound was performed in flight on adult patients during a 7-month period. Accuracy of the abdominal, cardiac, and lung components was determined by comparison to the presence of injury, primarily determined by computed tomography, and to required interventions.

RESULTS

HEMS providers performed ultrasound on 293 patients during a 7-month period, completing 211 full extended Focused Assessment with Sonography for Trauma (EFAST) studies. HEMS providers interpreted 11% of studies as indeterminate. Sensitivity and specificity for hemoperitoneum was 46% (95% confidence interval [CI] 27.1%-94.1%) and 94.1% (95% CI 89.2%-97%), and for laparotomy 64.7% (95% CI 38.6%-84.7%) and 94% (95% CI 89.2%-96.8%), respectively. Sensitivity and specificity for pneumothorax were 18.7% (95% CI 8.9%-33.9%) and 99.5% (95% CI 98.2%-99.9%), and for thoracostomy were 50% (95% CI 22.3%-58.7%) and 99.8% (98.6%-100%), respectively. The positive likelihood ratio for laparotomy was 10.7 (95% CI 5.5-21) and for thoracostomy 235 (95% CI 31-1758), and the negative likelihood ratios were 0.4 (95% CI 0.2-0.7) and 0.5 (95% CI 0.3-0.8), respectively. Of 240 cardiac studies, there was one false-positive and three false-negative interpretations (none requiring intervention).

CONCLUSIONS

HEMS providers performed EFAST with moderate accuracy. Specificity was high and positive interpretations raised the probability of injury requiring intervention. Negative interpretations were predictive, but sensitivity was not sufficient for ruling out injury.

Use of prehospital ultrasound in North America: a survey of emergency medical services medical directors

Background

Advances in ultrasound imaging technology have made it more accessible to prehospital providers. Little is known about how ultrasound is being used in the prehospital environment and we suspect that it is not widely used in North America at this time. We believe that EMS system characteristics such as provider training, system size, population served, and type of transport will be associated with use or non-use of ultrasound. Our study objective was to describe the current use of prehospital ultrasound in North America.

Methods

This study was a cross-sectional survey distributed to EMS directors on the National Association of EMS Physicians (NAEMSP) mailing list. Respondents had the option to complete a paper or electronic survey.

Results

Of the 755 deliverable surveys we received 255 responses from across Canada and the United states for an overall response rate of 30%. Of respondents, 4.1% of EMS systems (95% CI 1.9, 6.3) reported currently using ultrasound and an additional 21.7% (95% CI 17, 26.4) are considering implementing ultrasound. EMS services using ultrasound have a higher proportion of physicians (p < 0.001) as their highest trained prehospital providers when compared to the survey group as a whole. The most commonly cited current and projected applications are Focused Abdominal Sonography for Trauma (FAST) and assessment of pulseless electrical activity (PEA) arrest. The cost of equipment and training are the most significant barriers to implementation of ultrasound. Most medical directors want evidence that prehospital ultrasound improves patient outcomes prior to implementation.

Conclusions

Prehospital ultrasound is infrequently used in North America and there are a number of barriers to its implementation, including costs of equipment and training and limited evidence demonstrating improved outcomes. A research agenda for prehospital ultrasound should focus on patient-important outcomes such as morbidity and mortality. Two commonly used indications that could be a focus of standardized training programs are the FAST exam, and assessment of PEA arrest.

Clinical applicability of real-time, prehospital image transmission for FAST (Focused Assessment with Sonography for Trauma)

We evaluated a real-time, prehospital ultrasound image transmission system for use in focused assessment with sonography for trauma (FAST). The wireless, real-time ultrasound image transmission system comprised an ultrasound scanner with a convex abdominal transducer and a notebook computer connected to a 3 G wireless network for video data transmission. In our simulation experiment, ultrasonography was performed by emergency medical technicians (EMTs) on a human body phantom with simulated haemoperitoneum. Transmitted ultrasound video clips were randomly rearranged and presented to emergency physicians to make a diagnosis of haemoperitoneum. A total of 21 ultrasound video clips was used and 13 emergency physicians participated in the study. The sensitivity and specificity were 90.0% (95% Confidence Interval, CI, 83.5-94.6) and 85.3% (95% CI 78.4-90.7) respectively, and the accuracy of detecting abnormal ultrasound results was 87.7% (95% CI 83.8-91.6). Diagnosis of hemoperitonuem in trauma patients by an emergency physician based on the transmitted video images of FAST performed by an EMT is feasible, and has an accuracy of about 88%.

Effect of prehospital ultrasound on clinical outcomes of non-trauma patients--a systematic review

BACKGROUND

Advances in technology have made prehospital ultrasound (US) examination available. Whether US in the prehospital setting can lead to improvement in clinical outcomes is yet unclear.

OBJECTIVE

The aim of this systematic review was to assess whether prehospital US improves clinical outcomes for non-trauma patients.

METHOD

We conducted a systematic review on non-trauma patients who had an US examination performed in the prehospital setting. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the ISI Web of Science and the references of the included studies for additional relevant studies. We then performed a risk of bias analysis and descriptive data analysis.

RESULTS

We identified 1707 unique citations and included ten studies with a total of 1068 patients undergoing prehospital US examination. Included publications ranged from case series to non-randomized, descriptive studies, and all showed a high risk of bias. The large heterogeneity between the different studies made further statistical analysis impossible.

CONCLUSION

There are currently no randomized, controlled studies on the use of US for non-trauma patients in the prehospital setting. The included studies were of large heterogeneity and all showed a high risk of bias. We were thus unable to assess the effect of prehospital US on clinical outcomes. However, consistent reports suggested that US may improve patient management with respect to diagnosis, treatment, and hospital referral.

Prehospital emergency ultrasound: a review of current clinical applications, challenges, and future implications

Imaging modalities in the prehospital setting are helpful in the evaluation and management of time-sensitive emergency conditions. Ultrasound is the main modality that has been applied by emergency medical services (EMS) providers in the field. This paper examines the clinical applications of ultrasound in the prehospital setting. Specific focus is on applications that provide essential information to guide triage and management of critical patients. Challenges of this modality are also described in terms of cost impact on EMS agencies, provider training, and skill maintenance in addition to challenges related to the technical aspect of ultrasound.

Algorithm for the resuscitation of traumatic cardiac arrest patients in a physician-staffed helicopter emergency medical service

Survival rates following traumatic cardiac arrest (TCA) are known to be poor but resuscitation is not universally futile. There are a number of potentially reversible causes to TCA and a well-defined group of survivors. There are distinct differences in the pathophysiology between medical cardiac arrests and TCA. The authors present some of the key differences and evidence related to resuscitation in TCA, and suggest a separate algorithm for the management of out-of-hospital TCA attended by a highly trained physician and paramedic team.

Prehospital stroke diagnosis and treatment in ambulances and helicopters-a concept paper

Stroke is the second common cause of death and the primary cause of early invalidity worldwide. Different from other diseases is the time sensitivity related to stroke. In case of an ischemic event occluding a brain artery, 2000000 neurons die every minute. Stroke diagnosis and treatment should be initiated at the earliest time point possible, preferably at the site or during patient transport. Portable ultrasound has been used for prehospital diagnosis for applications other than stroke, and its acceptance as a valuable diagnostic tool "in the field" is growing. The intrahospital use of transcranial ultrasound for stroke diagnosis has been described extensively in the literature. Beyond its diagnostic use, first clinical trials as well as numerous preclinical work demonstrate that ultrasound can be used to accelerate clot lysis (sonothrombolysis) in presence as well as in absence of tissue plasminogen activator. Hence, the use of transcranial ultrasound for diagnosis and possibly treatment of stroke bares the potential to add to current stroke care paradigms significantly. The purpose of this concept article is to describe the opportunities presented by recent advances in transcranial ultrasound to diagnose and potentially treat large vessel embolic stroke in the prehospital environment.

Trauma ultrasound in civilian tactical medicine

The term “tactical medicine” can be defined in more than one way, but in the nonmilitary setting the term tactical emergency medical services (TEMS) is often used to denote medical support operations for law enforcement. In supporting operations involving groups such as special weapons and tactics (SWAT) teams, TEMS entail executing triage, diagnosis, stabilization, and evacuation decision-making in challenging settings. Ultrasound, now well entrenched as a part of trauma evaluation in the hospital setting, has been investigated in the prehospital arena and may have utility in TEMS. This paper addresses potential use of US in the tactical environment, with emphasis on the lessons of recent years' literature. Possible uses of US are discussed, in terms of both specific clinical applications and also with respect to informing triage and related decision making.

A pilot study examining the viability of a Prehospital Assessment with UltraSound for Emergencies (PAUSE) protocol

BACKGROUND

Prehospital ultrasound has been shown to aid in the diagnosis of multiple conditions that do not generally change prehospital management. On the other hand, the diagnoses of cardiac tamponade, tension pneumothorax, or cardiac standstill may directly impact patient resuscitation in the field.

STUDY OBJECTIVE

To determine if prehospital care providers can learn to acquire and recognize ultrasound images for several life-threatening conditions using the Prehospital Assessment with UltraSound for Emergencies (PAUSE) protocol.

METHODS

This is a prospective, educational intervention pilot study at an urban fire department with integrated emergency medical services (EMS). We enrolled 20 emergency medical technicians--paramedic with no prior ultrasonography training. Subjects underwent a 2-h training session on basic ultrasonography of the lungs and heart to evaluate for pneumothorax, pericardial effusion, and cardiac activity. Subjects were tested on image interpretation as well as image acquisition skills. Two bedside ultrasound-trained emergency physicians scored images for adequacy. Image interpretation testing was performed using pre-obtained ultrasound clips containing normal and abnormal images.

RESULTS

All subjects appropriately identified the pleural line, and 19 of 20 paramedics achieved a Cardiac Ultrasound Structural Assessment Scale score of ≥4. For the image interpretation phase, the mean PAUSE protocol video test score was 9.1 out of a possible 10 (95% confidence interval 8.6-9.6).

CONCLUSION

Paramedics were able to perform the PAUSE protocol and recognize the presence of pneumothorax, pericardial effusion, and cardiac standstill. The PAUSE protocol may potentially be useful in rapidly detecting specific life-threatening pathology in the prehospital environment, and warrants further study in existing EMS systems.

Diagnostic accuracy of focused assessment with sonography for trauma (FAST) examinations performed by emergency medical technicians

OBJECTIVE

We aimed to assess the diagnostic accuracy of focused assessment with sonography for trauma (FAST) examinations when used by emergency medical technicians (EMTs) to detect the presence of free abdominal fluid.

METHODS

Six level 1 EMTs (similar to intermediate EMTs in the United States) who worked at a tertiary emergency department in Korea underwent an educational program consisting of two one-hour didactic lectures that included the principles of ultrasonography, the anatomy of the abdomen, and two hours of hands-on practice. After this educational session, the EMTs performed FAST examinations on a convenience sample of patients from July 1 to October 5, 2009. These patients also received an abdominal computed tomography (CT) scan regardless of their chief complaints. The CT findings served as the definitive standard and were interpreted routinely and independently by emergency radiologists who were blinded to the study protocol. In addition, the EMTs were blinded to the CT findings. A positive CT finding was defined as the presence of free fluid, as interpreted by the radiologist. The sensitivity, specificity, predictive values, and their 95% confidence intervals (CIs) were calculated. Informed consent was obtained from all participating patients.

RESULTS

Among the 1,060 eligible patients with abdominal CT scans, 403 patients were asked to participate in the study, and 240 patients agreed. Of these 240 patients, 80 (33.3%) had results showing the presence of free fluid. Fourteen patients had a significant amount of peritoneal cavity fluid, 15 had a moderate amount of peritoneal cavity fluid, and 51 had a minimal amount of peritoneal cavity fluid. Compared with the CT findings, the diagnostic performance of the FAST examination had a sensitivity of 61.3% (95% CI, 50.3%-71.2%), specificity of 96.3% (95% CI, 92.1%-98.3%), positive predictive value of 89.1% (95% CI, 77.0%-95.4%), and negative predictive value of 83.2% (95% CI, 76.9%-88.2%). For a significant or moderate amount of peritoneal cavity fluid, the sensitivity was considerably higher (86.2%).

CONCLUSION

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. The validity of FAST examinations in prehospital care situations should be investigated further.

Real-time video streaming of sonographic clips using domestic internet networks and free videoconferencing software

OBJECTIVES

As the use of point-of-care sonography spreads, so too does the need for remote expert over-reading via telesonogrpahy. We sought to assess the feasibility of using familiar, widespread, and cost-effective existent technology to allow remote over-reading of sonograms in real time and to compare 4 different methods of transmission and communication for both the feasibility of transmission and image quality.

METHODS

Sonographic video clips were transmitted using 2 different connections (WiFi and 3G) and via 2 different videoconferencing modalities (iChat [Apple Inc, Cupertino, CA] and Skype [Skype Software Sàrl, Luxembourg]), for a total of 4 different permutations. The clips were received at a remote location and recorded and then scored by expert reviewers for image quality, resolution, and detail.

RESULTS

Wireless transmission of sonographic clips was feasible in all cases when WiFi was used and when Skype was used over a 3G connection. Images transmitted via a WiFi connection were statistically superior to those transmitted via 3G in all parameters of quality (average P = .031), and those sent by iChat were superior to those sent by Skype but not statistically so (average P = .057).

CONCLUSIONS

Wireless transmission of sonographic video clips using inexpensive hardware, free videoconferencing software, and domestic Internet networks is feasible with retention of image quality sufficient for interpretation. WiFi transmission results in greater image quality than transmission by a 3G network.

Combination of lung ultrasound (a comet-tail sign) and N-terminal pro-brain natriuretic peptide in differentiating acute heart failure from chronic obstructive pulmonary disease and asthma as cause of acute dyspnea in prehospital emergency setting

Introduction

We studied the diagnostic accuracy of bedside lung ultrasound (the presence of a comet-tail sign), N-terminal pro-brain natriuretic peptide (NT-proBNP) and clinical assessment (according to the modified Boston criteria) in differentiating heart failure (HF)-related acute dyspnea from pulmonary (chronic obstructive pulmonary disease (COPD)/asthma)-related acute dyspnea in the prehospital setting.

Methods

Our prospective study was performed at the Center for Emergency Medicine, Maribor, Slovenia, between July 2007 and April 2010. Two groups of patients were compared: a HF-related acute dyspnea group (n = 129) and a pulmonary (asthma/COPD)-related acute dyspnea group (n = 89). All patients underwent lung ultrasound examinations, along with basic laboratory testing, rapid NT-proBNP testing and chest X-rays.

Results

The ultrasound comet-tail sign has 100% sensitivity, 95% specificity, 100% negative predictive value (NPV) and 96% positive predictive value (PPV) for the diagnosis of HF. NT-proBNP (cutoff point 1,000 pg/mL) has 92% sensitivity, 89% specificity, 86% NPV and 90% PPV. The Boston modified criteria have 85% sensitivity, 86% specificity, 80% NPV and 90% PPV. In comparing the three methods, we found significant differences between ultrasound sign and (1) NT-proBNP (P < 0.05) and (2) Boston modified criteria (P < 0.05). The combination of ultrasound sign and NT-proBNP has 100% sensitivity, 100% specificity, 100% NPV and 100% PPV. With the use of ultrasound, we can exclude HF in patients with pulmonary-related dyspnea who have positive NT-proBNP (> 1,000 pg/mL) and a history of HF.

Conclusions

An ultrasound comet-tail sign alone or in combination with NT-proBNP has high diagnostic accuracy in differentiating acute HF-related from COPD/asthma-related causes of acute dyspnea in the prehospital emergency setting.

Trial registration

ClinicalTrials.gov NCT01235182.