Given the exploratory nature of the study objective, a scoping review was determined to be an appropriate method for mapping the existing literature. We aimed to categorize the contexts in which POCUS on the heart and great vessels of pediatric patients is currently being applied and to identify emerging themes across these contexts. To guide the research, an adapted Population, Intervention, Comparison, and Outcomes framework was outlined in the protocol (Appendix, https://doi.org/10.22470/pemj.2025.01207). Reporting followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, and standard scoping review methodology was used (9,10). This study was exempted from the institutional board approval as it did not use human participants.

This review included studies available up to August 2024 in which emergency physicians (EPs) used POCUS to assess conditions or diseases of the heart or great vessels of pediatric patients within EDs. Thus, articles were excluded primarily if they were not related to POCUS, did not study pediatric patients, heart or great vessels, or were performed in settings other than EDs. We additionally excluded studies that were case reports, reviews, abstract-only articles, duplicates, unfindable, not conducted in EDs with involvement of EPs, not about the use or interpretation of POCUS, or studies that used POCUS but did not evaluate its use in a specific condition or disease (Figure). Only peer-reviewed journal articles were included, with gray literature, such as conference proceedings or abstracts, and non-English articles excluded.

The following databases were searched up until August 2024: SpringerLink (n = 693), PubMed (n = 194), ScienceDirect (n = 185), Embase (n = 164), and Wiley (n = 98). A broad search strategy was employed to capture a wide range of ultrasonography-related studies in pediatric patients. Key terms across 4 categories were combined using Boolean operators as follows: “(Ultrasound) AND (emergency) AND (pediatric) AND (cardiac).” Multiple variations within each category were incorporated (e.g., “cardiac OR heart OR myocardial”), and the asterisk wildcard symbol was utilized to capture multiple word forms (e.g., “cardi* to retrieve both cardiac and cardiology”). A detailed example of the full search strategy for a specific database can be found in Appendix.

For level-1 screening, titles and abstracts were independently screened by 2 reviewers (MZ and SCD) using Rayyan (Rayyan Systems), an artificial intelligence-powered systematic review management platform, with all conflicts resolved by both reviewers. Subsequently, a level-2 screening was performed on the studies that passed the initial screening, based on the following 4 specific criteria, which reviewers answered with “yes” or “no.” The first question determined whether the study was conducted in EDs with EPs involved. The second asked whether POCUS was used on the heart or great vessels by EPs. The third required that at least 75% of the patients were younger than 18 years, and the fourth inquired if POCUS was applied to assess specific conditions or diseases in pediatric patients, excluding studies focused solely on image quality, interrater reliability, or POCUS training programs. For studies that met all 4 criteria, a standardized spreadsheet (Microsoft Excel) was used to extract general study characteristics, Template for Intervention Description and Replication checklist items, imaging frequencies and techniques, and additional information on the clinical applications, such as the conditions assessed (11).

A total of 1,334 records were initially reviewed by their titles and abstracts, leaving 69 full-text articles. Of these, 14 articles passed the 4 level-2 screening questions and were deemed eligible for inclusion. The Preferred Reporting Items for Systematic reviews and Meta-Analyses diagram illustrates this selection process (Figure). Table 1 summarizes the general features of the studies, including their target condition or disease, intervention applied, and outcomes (12-25). Table 2 shows the categorization of the studies, imaging techniques, and overall outcomes (12-25). Of note, some studies addressed multiple cardiac conditions or diseases, and were therefore included in more than 1 category.

Six studies were conducted on fewer than 50 patients, 3 studies on 50-100 patients, and 5 studies were conducted on more than 100 patients. Four of these studies were retrospective chart reviews and did not directly assess whether the targeted applications of POCUS could expedite treatment, improve outcomes, diagnose conditions or diseases, or identify specific parameters in future encounters (Table 1). All studies were carried out in pediatric EDs. The age ranges varied among the studies, with 9 studies reporting a mean or median age below 9 years and 6 studies reporting that above 9 years.

A total of 7 studies indicated the ultrasound frequency used, which consistently ranged from 1-5 MHz, covering both the lower and upper limits (12,14,15,17,19,20,24). Of the 6 studies that assessed pericardial effusion and (left) ventricular systolic dysfunction, 4 reported the frequency used and 3 of these employed a frequency of 2-4 MHz (14,20,24). The majority of the included studies contained at least 1 of the traditional echocardiographic views. The parasternal long-axis view was used in 6 studies (12,14,17,18,20,24). The parasternal short-axis view was also used in 6 studies (14,16-18,20,24). The apical 4-chamber view was used in 4 studies (14, 18,20,24). The apical 5-chamber view was used in 1 study (18). The most frequently used view was the subxiphoid view, which was employed in 9 studies (14,18-25).

In studies on cardiac POCUS to diagnose pericardial effusion, Miller et al. (24) reported a 100% sensitivity and 99.5% specificity. Similarly, Riera et al. (14) showed a 100% sensitivity and 99% specificity. Both studies also assessed left ventricular (LV) systolic dysfunction, where Miller et al. (24) reported a 100% sensitivity and 99.5% specificity, and Riera et al. (14) a 100% sensitivity and 99% specificity. Riera et al. (14) additionally investigated abnormal chamber size, reporting a 100% sensitivity and 95% specificity. In a sub-analysis of pediatric patients with prior cardiac disease, Hoffman et al. (20) found a 100% sensitivity and 97.5% specificity for pericardial effusion. For LV systolic dysfunction in the subgroup, the sensitivity and specificity were 100% and 98.9%, respectively. Lastly, Longjohn et al. (17) demonstrated that EPs had a 95% sensitivity and 83% specificity for detecting significant LV dysfunction, pericardial effusion, or inferior vena cava (IVC) collapsibility when compared with formal echocardiography performed by pediatric cardiologists.

Several studies also reported on the sensitivity and specificity of POCUS for determining dehydration status. Chen et al. (25) found a 97% sensitivity and 58% specificity for identifying pediatric patients with physician-determined clinical signs of dehydration using an IVC/Ao cutoff of 1, where IVC/Ao was defined as a ratio of the maximum anteroposterior diameters of the IVC and descending aorta. In a follow-up study, where a 5% increase in post-treatment weight was classified as severe dehydration, the sensitivity and specificity were 86% and 56%, respectively, with a 0.8 IVC/Ao cutoff (23). Jauregui et al. (21) used the same dehydration definition and cutoff value (0.8), reporting a 67% sensitivity and 71% specificity. They also used the IVC collapsibility index (fraction of collapse during inspiration) with an 80% cutoff, resulting in an 83% sensitivity and 42% specificity. In a later study, Özkan et al. (15) employed age-specific ratios, finding that a 0.96 IVC/Ao cutoff for children younger than 5 years yielded a 79.3% sensitivity and 68.2% specificity, while a ratio of 1.10 for children older than 5 years resulted in a 65.3% sensitivity and 62.5% specificity. Kwon et al. (19) used an IVC cross-sectional area to assess dehydration requiring fluid replacement, defined as a score of 1 or higher on a clinical dehydration scale. This approach yielded a 72% sensitivity and 89% specificity.

Severe dehydration, often defined as a weight loss of more than 5%, is a serious concern, with approximately 1,800,000 children dying annually from acute diarrhea, primarily due to dehydration-induced shock (26). Unfortunately, pre-admission weight is rarely available, making it quite difficult to determine whether a patient is severely dehydrated using this weight loss-based definition. The application of POCUS to the great vessels, specifically the IVC and aorta, has shown promise in the assessment of dehydration. Chen et al. (25) demonstrated that an IVC/Ao cutoff of 1 had a 97% sensitivity and 58% specificity for identifying pediatric patients with physician-determined clinical signs of dehydration. However, the study was limited by the absence of objective parameters to definitively classify dehydration.

In a follow-up study, Chen et al. (23) classified severe dehydration as a post-treatment weight increase of 5% and found an IVC/Ao cutoff of 0.8 had an 86% sensitivity and 56% specificity in identifying severe dehydration in pediatric patients. Similarly, Özkan et al. (15) demonstrated that the IVC/Ao increased as the degree of dehydration decreased post-fluid therapy, suggesting that the ratio may have utility in monitoring treatment progress. Interestingly, both studies observed that the aortic diameter did not change following fluid therapy.

Moreover, Özkan et al. (15) and others identified a correlation between the IVC/Ao and age, emphasizing the need to consider age-matched controls when using this parameter (27). In their study, they cited an IVC/Ao cutoff of 0.96 for children younger than 5 years (sensitivity, 79.3%; specificity, 68.2%) and 1.09 for children aged 5 years or older (sensitivity, 65.3%; specificity, 62.5%) (15). The age-dependent nature of the IVC/Ao demonstrates that without accounting for patient-specific parameters, over-reliance on the ratio may lead to misclassifying which patients are truly dehydrated. Since every study evaluating the IVC for volume assessment included congenital heart disease (CHD) in its exclusion criteria, there appears to be an agreement that patient-specific factors, particularly CHD, may restrict the applicability of these findings to individuals with typical anatomy as opposed to those with cardiac abnormalities.

More advanced techniques for measuring the IVC may further improve diagnostic accuracy. For example, Kwon et al. (19) demonstrated that using an IVC cross-sectional area to assess dehydration requiring fluid replacement (defined as a score on the clinical dehydration scale > 0) achieved a 72% sensitivity and 89% specificity. This method accounts for the elliptical shape of the IVC by measuring 2 perpendicular diameters, though the additional imaging time may be challenging in fast-paced EDs.

In contrast, the “kiss sign,” defined as 100% IVC collapsibility during inspiration, can be obtained quickly and has been shown to correlate with elevated uric acid, decreased bicarbonate, and decreased sodium concentrations (19,22). Rapid assessments like the kiss sign could demonstrate the core strength of POCUS in evaluating volume status, particularly by swiftly distinguishing between shock etiologies such as hypovolemic versus cardiogenic shocks. This is particularly valuable in scenarios where cardiogenic shock caused by myocarditis might resemble dehydration, where an erroneous assumption could worsen the patient’s condition if intravenous fluids are administered to correct presumed hypovolemia.

Many groups have demonstrated the utility of cardiac POCUS performed by EPs in EDs for identifying pericardial effusion and systolic dysfunction. The largest study was conducted by Miller et al. (24), in which 456 scans performed by 33 different pediatric EPs who underwent a brief training course were compared to those of POCUS experts with fellowship training. The group found that the sensitivity and specificity for diagnosing pericardial effusion and LV systolic dysfunction ranged from 99.5% to 100%, demonstrating that EPs trained to perform basic POCUS, albeit without fellowship training, could diagnose the conditions with high accuracy. A quality improvement project by Riera et al. (14), which included 94 examinations performed by 34 different EPs showed a sensitivity and specificity exceeding 99% for the conditions. They found that the median number of monthly POCUS examinations increased from 1 pre-protocol to 5 post-protocol, with the median rate of adequate studies rising from 0% to 55%. These results suggest that trained EPs are more likely to use POCUS, potentially leading to improved care.

While many studies have demonstrated the utility of POCUS in pediatric patients, most excluded those with known cardiac diseases, such as CHDs and myopathies. In a sub-analysis of their study, Hoffmann et al. (20) focused on patients with known cardiac abnormalities. Of the 104 patients in this group, 72% had known structural defects, 22% had acquired conditions, and 12% had arrhythmias. The diagnostic accuracy in this subgroup was similar to that of the broader population, with the sensitivity and specificity for pericardial effusion being 100% (95% confidence interval, 87.5%-100%) and 97.5% (91.3%-99.7%), respectively. For LV systolic dysfunction, the sensitivity and specificity were 100% (71.5%-100%) and 98.9% (93.8%-99.8%), respectively.

Three of the identified articles focused on the use of POCUS for managing or assessing cardiac emergencies. Multisystem inflammatory syndrome in children, a relatively new pediatric condition associated with coronavirus disease 2019, has significant morbidity and mortality. Kennedy et al. (18) conducted a retrospective cross-sectional study describing POCUS findings in an ED for patients with the diagnosis, of whom 71% were hospitalized in the pediatric intensive care unit (ICU), and 42% required dopamine infusions for hemodynamic support. They reported that POCUS played a critical role in determining whether to initiate inotropic infusions early or administer fluid boluses (14,18,20). One of the most compelling studies supporting the utility of POCUS was conducted by Chen et al. (16) in a pediatric ED in Rwanda. Pediatric residents were trained to perform POCUS on children presenting with shock. The 48-hour mortality rate among the 25 patients studied was 36%, with 11 children diagnosed with previously undetected CHDs. In 60% of the cases, the residents reported that POCUS led to changes in their assessment and management, likely by enabling differentiation between hypovolemic and cardiogenic shocks. This suggests that POCUS could significantly improve management by identifying otherwise undetected conditions. As per a retrospective chart review comparing outcomes in patients with acute HF hospitalized in the cardiac ICU, patients who received cardiac POCUS seemed to obtain intravenous medications for HF earlier in the ED (P = 0.100) (13).

The structural abnormality category was defined as applications that assessed abnormalities in the structure of the heart, rather than specific dysfunction of its components. Two studies fell into this category: 1 evaluated interventricular septal thickness with the aim of using it to assess hypertrophic cardiomyopathy, and the other examined children presenting with abnormal chamber sizes (12,14).

Hasan et al. (12) aimed to determine if EPs could accurately assess the interventricular septum end-diastolic thickness, which is critical for diagnosing hypertrophic cardiomyopathy. They found that the mean error in measurements made by EPs compared to pediatric cardiologists was only −0.046 (95% confidence interval, −0.08 to −0.01; P = 0.008). In a study on abnormal chamber size, Riera et al. (14) demonstrated that EPs had a 100% sensitivity (54%-100%) and 95% specificity (89%-99%) for detecting abnormal chamber sizes.

This study has inherent limitations associated with the goal of identifying research specifically conducted by EPs. For instance, many relevant studies on the utility of POCUS for similar conditions, such as pericardial effusion in children, have been conducted in pediatric ICUs, which may offer additional insights applicable to EDs (28,29). We also collected details on imaging techniques, such as frequencies, used in each study to evaluate whether specific parameters were consistent across use cases (Table 2). However, less than half of the studies reported their scanning modes or frequencies. The exceptions were studies focused on pericardial effusion and reduced ventricular function, where most reported scanning frequencies of 2-4 MHz (14,20,24). As frequency directly affects imaging resolution (30), future research could benefit from reporting and standardizing these parameters across specific applications and comparing frequencies to optimize outcomes. An emerging application of cardiac POCUS for future research involves investigating whether cardiac arrest identified by POCUS has clinical utility in pediatric EDs. In our review, the studies found in this area were excluded given they only focused on interrater reliability of cardiac standstill measurements (31,32).