Integration of Paramedic-led Echocardiography in Pulseless Electrical Activity (PEA) During Out-of-hospital Cardiac Arrest: An Education and Simulation Study.

Latta, Hannah
Tunnage, Bronwyn
Swain, Andrew
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Doctor of Health Science
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Auckland University of Technology

During out-of-hospital cardiac arrest, patients presenting in pulseless electrical activity (PEA) may receive inappropriate care if a manual pulse check determines pulselessness. This study created the Cardiac Arrest Focused Echocardiography (CAFE) exam incorporating a pre-imaging technique to reduce the time spent acquiring an ultrasound image. Paramedic participants were trained to use the CAFE exam and to record an 8 second image during the pulse check pause. The paramedic performing the CAFE exam is supernumerary to standard cardiac arrest proceedings and must not interrupt the delivery of cardiopulmonary resuscitation (CPR). Real-time ultrasound image interpretation during the CPR cycle determined the presence of a pericardial effusion, tamponade physiology, and heart function.

Research Aim. To determine if paramedics can acquire an ultrasound image during the 10 second pulse check pause in simulated PEA cardiac arrest. Secondary aims focus on ultrasound image acquisition quality, interpretation, and retention of learned knowledge.

Method. The study recruited 30 paramedics from Wellington, New Zealand. This study adhered to the reporting guidelines set by the International Network for Simulation-based Paediatric Innovation Research and Education (INSPIRE). Participants were divided into two equal groups and completed three trial phases between January to March 2022. Phase I involved an eLearning program covering ultrasound theory, ultrasound device orientation, echocardiogram views, PEA, cardiac arrest ultrasound, and cardiac arrest considerations for Māori. Phase II involved 4.5 hours of classroom theoretical and practical education, including competency-based assessments. The assessments included simulations testing hands-off time (HOT), pathological image interpretation, echocardiography (echo) skills and a knowledge test. The phase II assessments were replicated in phase III to assess knowledge and skill retention.

Findings. The mean HOT was 9.6 seconds (SD = 2.9, 95% CI [9.3, 10.0]), with 47.7% of scans achieved within the 10 second pulse check pause. Image adequacy was measured using the Cardiac Ultrasound Structural Assessment Scale (CUSAS). The results showed that 73.9% ( 95% CI [67.8, 79.4]) met the desired standard of ≥ 3. Of the 243 CAFE exam interpretations, paramedics were correct in 91.9% of cases (95% CI [88.5, 94.5]). The accuracy of interpreting left ventricular squeeze was relatively low, with overall accuracy at 73.6% (95% CI [67.6, 79.0]). In contrast, valvular opening was consistently high, with 100% (95% CI [95.8, 100]) of cases in phase II and 99.3% (95% CI [96.4, 99.9]) in phase III. Overall, the knowledge quiz showed 67.2% (95% CI [53.2, 79.3]) satisfying the ≥80% pass requirement. This result did not meet the study aim. A binary logistic regression explored the association between HOT, study phase and station compared with the comparison station. An odds ratio of 7.69 (95% CI [1.35, 9.09]) with the ‘person effect’ was associated with an increased HOT due to image acquisition difficulty for this station.

Conclusion. This study found that paramedics can acquire and interpret ultrasound images during pulse check pauses in simulated PEA cardiac arrest. Despite limited training, study participants averaged 9.6 seconds for ultrasound examinations, with 47.7% meeting the 9.99-second time limit. Paramedic participants demonstrated adequate image acquisition and strong interpretation abilities. The findings showed that most participants were able to retain acquired knowledge and skills with the education intervention offered, but others will require ongoing training and support. This study highlights the potential of ultrasound application in PEA cardiac arrest, emphasising the need for strategies to optimise HOT and address challenges such as equipment costs, educational standards, and clinical governance. Ultrasound use in out-of-hospital cardiac arrest should focus on improving patient assessment accuracy by providing clinical information for differential diagnoses, and guiding treatment and transport decisions.

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