Ultrasound in Emergency Medicine
A Pilot Study Examining the Viability of a Prehospital Assessment with UltraSound for Emergencies (PAUSE) Protocol

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Abstract

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.

Introduction

Over the past two decades, bedside ultrasound use has continued to expand to a variety of applications to help answer focused clinical questions, such as whether a trauma patient has cardiac tamponade, or whether a patient with shortness of breath has a pneumothorax. Bedside ultrasound is an ideal device for the prehospital setting because it can be rapidly applied, is increasingly portable, and can provide improved diagnostic accuracy over physical examination.

In the critically ill or seriously injured patient, an accurate physical examination is vital to the care of the patient. However, it is generally recognized that the physical examination is fairly insensitive when compared to advanced imaging modalities. Similarly, the use of auscultation to detect a pneumothorax/hemothorax in a penetrating chest trauma patient is only 58% sensitive (1). In contrast, the use of ultrasound in the hands of emergency physicians has been shown to be very sensitive in the detection of pericardial effusions and pneumothoraces, with reported sensitivities as high as 99% 2, 3, 4.

The Focused Assessment with Sonography for Trauma (FAST) has been shown to be an effective tool to rapidly identify hemoperitoneum in the Emergency Department (ED). Although it has also been studied in the prehospital setting, the early detection of intra-abdominal free fluid before hospital arrival may not immediately change the management of the patient 5, 6. On the other hand, the diagnosis of cardiac tamponade or tension pneumothorax may guide urgent actions during resuscitation in both medical and trauma emergency medical services (EMS) patients, or at least direct proper destination decisions by EMS providers 7, 8, 9. Prehospital ultrasound has already been shown to aid in diagnosis and triage of fractures, abdominal pain, or potential hemoperitoneum in remote prehospital settings, all of which can affect critical decisions regarding transport and immediate care 10, 11. Additionally, in the case of cardiac arrest, by confirming cardiac standstill with ultrasound, this may allow providers to more assuredly cease futile advanced cardiac life support (ACLS) efforts and redirect resources and personnel to other patients (12).

We created the Prehospital Assessment with UltraSound for Emergencies (PAUSE) protocol to serve as a tool for the paramedic to rapidly and accurately identify life-threatening conditions that would require immediate interventions, as well as to guide continued resuscitative efforts in a cardiac arrest situation. When designing the PAUSE protocol, we chose to include an assessment for pericardial effusion, pneumothorax, and the presence/absence of cardiac activity, because these pathologies can be difficult to accurately assess with physical examination alone and because they are readily detectable by bedside ultrasonography. The goal of this study is to determine if prehospital care providers can learn to acquire and recognize ultrasound images for several emergent life-threatening conditions, including pneumothorax, pericardial effusion, and cardiac standstill, using the novel PAUSE protocol after a brief training session.

Section snippets

Study Design

This prospective, educational intervention study was approved by the study institution’s Institutional Review Board.

Population and Setting

Subjects were professional firefighter paramedics with the City of Orange Fire Department who voluntarily agreed to participate in this study.

Experimental Protocol

Participants received study information sheets, and verbal informed consent was obtained. To simulate a reasonable amount of time for ultrasound instruction within a paramedic training curriculum, we limited our didactic time to a single 2-h

Results

We enrolled 20 male paramedics with no prior experience in ultrasound. Overall, they scored an average of 9.1 correct answers out of a possible 10 on the image recognition test (95% confidence interval 8.6–9.6). The lowest image recognition test score was a 6 out of 10 by one participant, whereas half of the paramedics attained the maximum of 10 (Figure 3). Of note, there was one particular question requiring the paramedics to identify cardiac standstill that was answered incorrectly by six

Discussion

There is a growing body of literature evaluating the use of bedside ultrasound in the prehospital setting. Previous studies have suggested that paramedics could be taught to perform FAST scans (5). However, the immediate usefulness of a prehospital FAST scan to the prehospital provider is limited, given that many etiologies of a positive FAST scan, particularly those causing free intra-abdominal fluid, are not readily managed in the prehospital setting. We developed the PAUSE protocol to

Conclusion

Using a brief lecture and hands-on experience, paramedics seem to be capable of acquiring and interpreting ultrasound images for several immediately life-threatening conditions. Whether the PAUSE protocol can be successfully initiated in the field still needs to be determined. Prehospital providers would need further education on procedures and more training on recognizing conditions addressed in the protocol that require immediate intervention, versus those that are stable. In the future,

Acknowledgments

We would like to thank Susan Goodrich, City of Orange Fire Department, for her assistance with this project. We would also like to thank Nichole Niknafs and Mary Jane Jeena Vennat for being ultrasound models during the hands-on sessions of this project.

References (16)

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