Interpretation of Cardiac Standstill in Children Using Point-of-Care Ultrasound

Study objective: This study aimed to determine the level of agreement among pediatric emergency medicine (PEM) physicians in whether various point-of-care ultrasound (POCUS) video clips represent cardiac standstill in children and to highlight the factors that may be associated with the lack of agreement. Methods: A single, online, cross-sectional, convenience sample survey was administered to PEM attendings and fellows with variable ultrasound experience. PEM attendings with an experience of 25 cardiac POCUS scans or more were the primary subgroup based on ultrasound proficiency set by the American College of Emergency Physicians. The survey contained 11 unique, 6-second video clips of cardiac POCUS performed during pulseless arrest in pediatric patients and asked the respondent if the video clip represented a cardiac standstill. The level of interobserver agreement was determined using the Krippendorff's a (Ka) coefficient across the subgroups. Results: A total of 263 PEM attendings and fellows completed the survey (9.9% response rate). Of the 263 total responses, 110 responses were from the primary subgroup of experienced PEM attendings with at least 25 previously seen cardiac POCUS scans. Across all video clips, PEM attendings with 25 scans or more had an acceptable agreement (Ka=0.740; 95% CI 0.735 to 0.745). The agreement was the highest for video clips wherein the wall motion corresponded to the valve motion. However, the agreement fell to unacceptable levels (Ka=0.304; 95% CI 0.287 to 0.321) across video clips wherein the wall motion occurred without the valve motion. Conclusion: There is an overall acceptable interobserver agreement when interpreting cardiac standstill among PEM attendings with an experience of at least 25 previously reported cardiac POCUS scans. However, factors that may influence the lack of agreement include discordances between the wall and valve motion, suboptimal views, and the lack of a formal reference standard. More specific consensus reference standards of pediatric cardiac standstill may help to improve interobserver agreement moving forward and should include more specific details regarding the wall and valve motion.