POCUS in Pediatric Cardiac Arrest: What's the Latest?

Much has been written, including by me in this column, about POCUS in adult cardiac arrest. What about pediatric cardiac arrest? As our pediatric colleagues like to remind us, children aren't just little adults, so what does the pediatric-specific literature have to say about the use of POCUS in these patients? The PULSE protocol was proposed as a structured method to evaluate pediatric patients in cardiac arrest.1 The authors proposed that ultrasound be used for a few high-yield uses. First, the linear transducer should be placed over the carotid or femoral artery to judge quality of compressions and maintained in this position during pulse checks to quickly identify a pulse. Second, a phased-array transducer should be used during pulse checks to evaluate for the presence of organized cardiac activity, as well as to identify reversible causes such as cardiac tamponade. Finally, ultrasound can also be used to identify correct intraosseous access (IO) and ET tube placement. This article was published in 2023, and data on its usefulness and feasibility are hopefully forthcoming. The PULSE protocol is promising, but how do we manage the unique challenges of obtaining these images? We know this can be tough enough in adults and can lead to delays in resuming CPR—what about in kids? A recent study from Pediatric Emergency Care looked at this question. The authors used 22 emergency department (ED) clinicians to evaluate cardiac and femoral artery views in 22 stable children, mimicking the conditions of cardiac arrest (limiting time frames for acquisition of images).2 They found that, overall, clinicians were successful in obtaining cardiac images (86% of apical 4 and 94% of subxiphoid) on first attempt, but interestingly, only 70% of femoral artery views. In their study, there was no meaningful difference in successful acquisition between “experts” and “non-experts.” Once these images are obtained, interpretation can also be a challenge. Data in adults have demonstrated variability in what is considered “cardiac standstill”, which is illlustrated in this video.3 A 2023 study from the Journal of Emergency Medicine looked for agreement in this diagnosis in pediatric patients.4 Two hundred and sixty-three pediatric emergency physicians reviewed a survey with 11 videos captured during pulseless arrests and classified which videos demonstrated cardiac standstill. In their study, there was broad disagreement, particularly among those clips that showed some degree of wall motion and not just isolated valve movement. This study highlights that, just like in adults, there is no clear reference standard for what constitutes cardiac standstill. Ultrasound likely has potential in pediatric cardiac arrest, such as assisting in pulse checks or identifying reversible causes. However, there remain several important unanswered questions, primarily whether an algorithm can have meaningful impact and the establishment of a reference standard for cardiac standstill.