Age-specific considerations in aetiology of paediatric out-of-hospital cardiac arrest

Dear Editor,

The recent advancements in paediatric out-of-hospital cardiac arrest (OHCA) management underscore the importance of understanding age-specific aetiologies and their influence on neurological outcomes. Based on our analysis of 296 paediatric patients up to 16 years of age treated by helicopter emergency medical services (HEMS) between 01–01–2011 and 31–12–2021, we noted that favourable neurologicaloutcomes, defined by a Cerebral Performance Category (CPC) score of 1 or 2 at 30 days post-arrest, were achieved in 18.9% of cases [1]. By examining age-specific trends (Fig. 1), we aim to gain a deeper understanding of the aetiology and to highlight critical aspects for improving favourable neurological outcome [1, 2].

Fig. 1

Age specific categorization of the aetiology of paediatric out of hospital cardiac arrest

Cardiac vs. non-cardiac aetiology across ages

In our cohort, 23 cases of paediatric OHCA were due to cardiac causes, with a median patient age of 10 years. Among these, 65% had a known cardiac comorbidity, and immediate bystander cardiopulmonary resuscitation (CPR) was often initiated, suggesting greater awareness among caregivers trained for critical events. Key cardiac factors included congenital heart defects (e.g., hypoplastic left heart syndrome), acquired cardiomyopathies and arrhythmias (e.g., Long QT syndrome) [3]. Non-cardiac causes, however, accounted for a significant portion (n = 233, 78%) of arrests and varied in origin across age groups, underscoring the need for age-targeted strategies. These non-cardiac aetiologies included respiratory insufficiency (mostly due to asphyxia as well as respiratory infections), trauma and metabolic derangements.

Infants (< 1 Year): high risk of hypoxia-related arrests

Infants demonstrate a unique vulnerability to hypoxia-related arrests, primarily due to physiological factors such as higher metabolic rates, lower functional residual capacity and immature cardiovascular response [4]. In this age group, 89.3% of cases were non-traumatic, with sudden infant death syndrome (SIDS) and bronchopulmonary aspiration accounting for 37.5% and 25% of cases, respectively. The diagnosis of SIDS is made when there is no explanation for cardiac arrest found after thorough investigation. Pathophysiological mechanisms remain mostly unclear, while several risk factors were identified such as prone sleeping, over-heating, smoke exposure and infection [5]. Infants with return of spontaneous circulation (ROSC) upon arrival of HEMS had significantly improved neurological outcomes (p < 0.05). This age group had a high incidence (53.6%) of asystole as the initial rhythm with no prevalence of favourable neurological outcome, emphasizing the importance of rapid intervention to restore oxygenation and minimize neurological damage (Table 1).

Table 1 Detailed baseline characteristics of patient group < 1 year old. Adjusted to 30-day favourable neurological outcome defined as cerebral performance categories (CPC) 1 and 2. Data presented in n (%)

Preschoolers (1–6 Years): drowning as the leading cause

In preschool-aged children, drowning was the predominant cause of cardiac arrest, responsible for 37.7% of cases. Many of these incidents occurred in swimming pools, where immediate bystander reactions, mainly through lifeguards, contributed to improved survival and neurological outcomes (p < 0.001, Table 2). This age group benefits substantially from preventive measures and caregiver education on basic life support skills [6]. Traumatic events, primarily from traffic accidents, accounted for 33.4% of cases. The lower frequency of nighttime missions in preschool-aged children may be attributed to their daytime activity patterns, increased supervision during waking hours, reduced engagement in risky behaviours, and the timing of common incidents such as drowning, which typically occur during daytime periods (Table 2).

Table 2 Detailed baseline characteristics of patient group 1–6 years old. Adjusted to 30-day favourable neurological outcome defined as cerebral performance categories (CPC) 1 and 2. Data presented in n (%)

School-aged and adolescent children (7–16 Years): high incidence of traumatic arrests

For children aged 7–16, traumatic causes—primarily traffic accidents and falls from heights (both 15.9%)—comprised 45.3% of cardiac arrest cases. Non-traumatic causes, such as acquired cardiomyopathies and arrhythmias, were also prevalent (54.7%). Unlike in younger age groups, trauma-related OHCAs were associated with lower rates of favourable neurological outcomes, reflecting the challenge of managing traumatic injuries before emergency medical service (EMS) arrival. Standardized guidelines for paediatric traumatic cardiac arrest (TCA) remain limited, underscoring a gap in age-specific treatment strategies for this group. Although age differences alone were not statistically significant in predicting favourable outcomes, traumatic aetiologies notably influenced survival rates [7] (Table 3).

Table 3 Detailed baseline characteristics of patient group 7–16 years old. Adjusted to 30-day favourable neurological outcome defined as cerebral performance categories (CPC) 1 and 2. Data presented in n (%)

Geographical impact on outcomes

Geographical location further influences outcomes, with urban and remote settings exhibiting pronounced differences. Urban settings typically allowed for faster EMS response, greater access to advanced medical resources, and higher bystander CPR rates. In contrast, remote areas faced prolonged response times and limited resources, leading to lower survival and neurological outcomes. HEMS teams in Switzerland were generally able to reach any remote location in a reasonable time, averaging 18 min for arrival, although pre-arrival interventions by ground bound EMS proved crucial in managing initial care [8, 9]. In our cohort many of the drowning accidents happened in swimming pools (46.9%, n= 30) with a higher survival rate compared to unsupervised drowning accidents in natural waters in rural areas, which often had long down-times due to recovery issues. Remote areas are more frequently associated with high-risk recreational activities, leading to an increased incidence of traumatic accidents, which generally have lower survival rates [7].

Conclusions

The age-specific aetiology and outcomes in paediatric OHCA emphasize the need for tailored approaches in resuscitation and post-resuscitation care. Infants are especially susceptible to hypoxia-related arrests, while preschool-aged children are most at risk for drowning-related incidents, where early intervention significantly improves neurological outcomes. In school-aged and adolescent children, the high rate of traumatic cardiac arrests necessitates further development of paediatric-focused guidelines for traumatic cardiac arrest management.

Enhancing public awareness, expanding CPR training with a focus on children, and optimizing EMS infrastructure are vital, particularly in rural areas. Recognizing age-specific risks and implementing timely interventions aligned with the causes of arrest can ultimately improve survival and neurological outcomes for paediatric patients experiencing OHCA.

In addition, preventive strategies such as promoting safe sleep practices for infants, ensuring vigilant water safety and supervision for toddlers and preschoolers, and enforcing protective measures in sports and traffic settings for older children are essential. Public health campaigns targeting caregivers and schools can play a pivotal role in reducing the incidence of preventable cardiac arrests among children.

Sincerely,

Deliah Bockemuehl.