a b s t r a c t

Background: Dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is an important prognostic factor in Pediatric out-of-hospital cardiac arrest (OHCA). The recognition of cardiac arrest by dispatcher is a key factor for successful DA-CPR. In this study, we evaluated the association between pediatric age and dispatcher recogni- tion.

Methods: A retrospective observational study was designed using a nationwide OHCA registry. Patients under 19 years of age were enrolled. Patients were categorized into four groups according to age (<1 year, 1-6 years, 7-13 years, and 14-18 years). The primary outcome was cardiac arrest recognition by dispatcher. A multivariable lo- gistic regression analysis was performed.

Results: A total of 2754 pediatric OHCA patients were enrolled. A negative trend was observed between age and dispatcher performance (p < 0.01). The rate of cardiac arrest recognition was highest in patients under one year of age (61.5%) and lowest in patients ages 14-18 years old (47.1%). Patients in the 7-13 years and 14-18 years age groups were both associated with a decreased rate of recognition (adjusted odds ratio with 95% confidence interval: 0.55 (0.41-0.74) and 0.44 (0.34-0.57), respectively). In the interaction analysis, the association between age and outcomes was more prominent in patients with non-Medical causes.

Conclusion: Patients ages 7-18 years old were negatively associated with cardiac arrest recognition and DA-CPR instruction provision within optimal timeframes compared to those younger than one year old. Development of a tailored protocol could be considered according to age and cause of arrest for better dispatcher performance in pediatric OHCA patients.

(C) 2022

1. Introduction

Early recognition of cardiac arrest by emergency medical dispatchers is an important step in the initial activation of the emergency medical service (EMS) system. Non-recognition of cardiac arrest by dispatchers during emergency calls negatively affects survival outcomes in out-of- hospital cardiac arrest (OHCA) [1] however, it is often difficult for dis- patchers to recognize cardiac arrest immediately because of several

* Corresponding author at: Department of Emergency Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, 20 Boramae-ro 5-gil, Sindaebang-dong, Dongjak-gu, Seoul, Republic of Korea.

E-mail addresses: [email protected] (T.H. Kim), [email protected] (J.H. Jung).

barriers: the victim’s agonal respiration or gasping, caller’s factors, and dispatcher’s factors [2-4].

Dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is im- portant for the prognosis of OHCA by minimizing No-flow time until the arrival of trained EMS providers to the scene [5-8]. Several previous studies have reported the positive effects of successful DA-CPR on OHCA outcomes in the pediatric population [5,9-11]. Recognition of cardiac ar- rest by the dispatcher is an essential prerequisite for successful DA-CPR and bystander CPR; however, less is known about the factors related to cardiac arrest recognition by dispatchers, which could lead to successful DA-CPR and better clinical outcomes in pediatric OHCA.

In this retrospective analysis, we evaluated the recognition rate ac- cording to age of pediatric OHCA and analyzed the association between

https://doi.org/10.1016/j.ajem.2022.05.038

0735-6757/(C) 2022

age group and successful cardiac recognition by the emergency medical dispatcher using the nationwide OHCA registry.

1. Methods
   1. Study design and setting

A retrospective observational study was designed using a nation- wide OHCA registry dataset from 2015 to 2019 in Korea. Korea has a public uniformed fire-based EMS system that provides a single-tiered service level. Emergency calls in Korea are received when a caller dials “119.” Each of the 17 provinces over the entire nation has an emergency response headquarters for fire and disaster that usually operate one or two emergency dispatch centers per province. The dispatch centers pri- marily respond to all emergency calls received within the province by call-takers. If the primary call-taker recognizes that the call is regarding emergency medical conditions such as cardiac arrest, the call is transferred to emergency medical dispatchers to gather more informa- tion regarding the case and provide pre-arrival instructions, such as in- structions for DA-CPR. The first process by medical dispatchers is to answer two key questions to determine whether the patient is in car- diac arrest regardless of the patient’s age. The first question is, “Is the pa- tient conscious?”, and the second question is, “Is the patient breathing normally?” If the answers to both questions are “no” and dispatcher thinks that there is a high probability of cardiac arrest, DA-CPR instruc- tions are provided according to the pre-written protocol. There are 3 dif- ferent DA-CPR instruction protocols according to the age of the patient (age younger than one year (12 months), 1-9 years old and age older than 9 years old (including adult patient)). There aren’t separate cardiac arrest recognition protocol according to the patient’s age.

• 1. Study population

Pediatric OHCA patients under 19 years of age registered in the na- tionwide database from January 2015 to December 2019 were initially enrolled. Patients who did not receive resuscitation due to obvious death and pre-written do-not-resuscitation (DNR) orders were ex- cluded from the analysis. Additionally, cases were excluded if the car- diac arrest was first witnessed by EMS providers at the scene or if bystander CPR was already performed before the dispatcher’s instruc- tion. Cases with missing time variables regarding dispatcher response were excluded as well.

• 1. Database and variables

The nationwide OHCA registry database used in this study is a com- bination of several data sources. The emergency dispatch registry con- tains time variables of each event (time of call, time of DA-CPR instruction) and other key information during dispatch, such as circum- stances of emergency, recognition of cardiac arrest, and provision of dispatcher-assisted CPR instruction. The dispatch registry was com- pleted by an emergency medical dispatcher that managed OHCA cases during and after dispatching. Emergency medical dispatchers are usu- ally certified nurses or emergency medical technicians who are trained to recognize and provide instructions for cardiac arrest calls. Medical di- rectors review audio recording of certain proportions (at least 10%) of OHCA cases received by the dispatch center on a monthly basis and pro- vide appropriate feedback and training. The EMS ambulance run sheet and EMS cardiac arrest registry contain Utstein factors, such as witness status, bystander CPR at EMS arrival, initial ECG rhythm, response time interval (call to EMS scene arrival), scene time interval (scene arrival to departure for hospital), and transport time interval (scene departure to hospital arrival). They were completed by dispatched EMS providers. Hospital medical records were extracted by trained medical reviewers according to the protocol of the Korea Centers for Disease Control and Prevention (KCDC). Survival outcomes, such as survival to discharge

and Good neurologic outcomes (cerebral performance category [CPC] 1 or 2) were recorded based on the hospital medical records. Autopsy reports were not included in the medical record review. A detailed de- scription of the nationwide registry has been reported previously [12,13].

• 1. Study exposure and interaction variable

The main exposure variable of the study was the ages of pediatric OHCA patients. The patient was calculated based on the date of birth in the medical records retrieved by a trained medical reviewer. Age was categorized into four groups according to the calculated ages of the patients (age younger than one year (12 months), 1-6 years old, 7-13 years old, and 14-18 years old). The cause of arrest was obtained from the hospital medical records. The medical reviewer chose the most probable cause of cardiac arrest among the defined causes of arrest in the Utstein template [14]. For the interaction analysis, we categorized the cause of arrest into two groups (medical vs. non-medical).

• 1. Study outcome

The primary outcome of the study was successful cardiac arrest rec- ognition by an emergency medical dispatcher during the emergency call taking process. Successful cardiac arrest recognition was defined when the dispatcher checked the case as cardiac arrest in the electronic dis- patcher registry during the call-taking process. The secondary outcome was successful DA-CPR instruction provided by the dispatcher to the caller within 120 s from the start of the call. DA-CPR delivery within 120 s is the recommended performance measure for high-performance emergency medical dispatch systems according to the American Heart Association (AHA) [15]. The tertiary outcome was the provision of by- stander CPR (whether dispatcher-assisted or not) at the scene that was recorded by the dispatched EMS team that arrived at the scene.

• 1. Statistical analysis

Patient demographics and outcomes were compared according to age group. Continuous variables were presented either as the mean and standard deviation (compared with ANOVA) or the median and in- terquartile range (compared with the Kruskal-Wallis test) according to the distribution. Categorical variables were presented as proportions and compared using the chi-square test. A multivariable logistic regres- sion analysis was performed to test the association between the age group and successful cardiac arrest recognition by the dispatcher and other outcomes. Potential confounders, such as cause of arrest (medical vs. non-medical), sex, presence of underlying comorbidities, year, place of arrest, witness, and initial ECG rhythm were adjusted. The adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated. An interaction analysis was performed to compare the different effects of age on the outcomes according to the presumed cause of cardiac ar- rest (medical/non-medical).

• 1. Ethics statement

The study was approved by the Seoul National University Hospital Institutional Review Board and informed consent (IRB No.1103-153- 357).

1. Results

A total of 3244 pediatric OHCA cases were registered in the nation- wide database between 2015 and 2019. In cases of EMS CPR not attempted or withdrawn at the scene (n = 173), EMS witnessed cardiac arrest at the scene or during transport (n = 273). Bystander CPR per- formed prior to dispatcher connection (n = 41) and missing time

Fig. 1. Patient enroll process.

OHCA, out-of-hospital cardiac arrest; EMS, emergency medical service; CPR, cardiopulmonary resuscitation.

variables (n = 3) were excluded. After serial exclusion, 2754 cases were enrolled for the final analysis (Fig. 1).

The number of OHCA cases and crude rate of study outcomes accord- ing to age are plotted in Fig. 2. The rate of cardiac arrest recognition, DA- CPR instruction within 120 s, and bystander CPR at the scene all de- creased as age increased (p for trend <0.01 for all three outcomes). Basic demographic, EMS dispatch variables, and outcomes are shown according to the age group in Table 1. The distribution of the presumed cause of cardiac arrest differed significantly across age groups. The pro- portion of medical causes was highest in those younger than one year old (53.3%) and lowest in patients ages 14-18 years old (29.9%). The rate of cardiac arrest recognition during an emergency call was also

highest in those under one year old (61.5%) and lowest in patients ages 14-18 years old (47.1%).

Results of the multivariable logistic regression analysis (Table 2) showed that patients ages 7-13 years old and 14-18 years old were both associated with a decreased chance of cardiac arrest recognition by the dispatcher (AOR with 95% CI: 0.55 (0.41-0.74) and 0.44 (0.34-0.57], respectively). Only patients between 14 and 18 years old were significantly associated with a decreased rate of bystander CPR at EMS arrival (AOR with 95% CI: 0.47 (0.37-0.60)). In the interaction analysis, the magnitude of the association between the age group and outcomes differed according to the presumed cause of cardiac arrest (Table 3). All age groups equal to or older than one year old were

Fig. 2. Number of patients and rate of outcome according to patient age. The rate of cardiac arrest recognition, DA-CPR instruction within 120 s, and bystander CPR at the scene all decreased as age increased. OHCA, out-of-hospital cardiac arrest; CPR, cardiopulmonary resuscitation; DA-CPR, dispatcher-assisted cardiopulmonary resuscitation.

Table 1

Demographic characteristic of pediatric OHCA patients according to age-group.

	Variables	Total		<1 year		1-6 years		7-13 years		14-18 years	p-value
		N (%)		N (%)		N (%)		N (%)		N (%)
N		2754		833		529		424		968
Year											0.45
	2015	570 (20.7%)		161 (19.3%)		107 (20.2%)		94 (22.2%)		208 (21.5%)
	2016	546 (19.8%)		159 (19.1%)		115 (21.7%)		88 (20.8%)		184 (19.0%)
	2017	545 (19.8%)		170 (20.4%)		109 (20.6%)		87 (20.5%)		179 (18.5%)
	2018	537 (19.5%)		182 (21.8%)		86 (16.3%)		74 (17.5%)		195 (20.1%)
	2019	556 (20.2%)		161 (19.3%)		112 (21.2%)		81 (19.1%)		202 (20.9%)
Age	mean (SD)	8.43 (7.28)		0.33 (0.24)		3.56 (1.78)		10.90 (2.12)		16.98 (1.35)	<0.01
Sex											0.03
	Male	1747 (63.4%)		508 (61.0%)		324 (61.2%)		266 (62.7%)		649 (67.0%)
Presumed cause of arrest											<0.01
Medical		1469 (53.3%)	694 (83.3%)		278 (52.6%)		208 (49.1%)		289 (29.9%)
Traumatic		776 (28.2%)	20 (2.4%)		123 (23.3%)		140 (33.0%)		493 (50.9%)
Overdose		26 (0.9%)	1 (0.1%)		7 (1.3%)		2 (0.5%)		16 (1.7%)
Drowning/submersion		140 (5.1%)	9 (1.1%)		56 (10.6%)		30 (7.1%)		45 (4.6%)
Asphyxia		319 (11.6%)	103 (12.4%)		60 (11.3%)		40 (9.4%)		116 (12.0%)
Others		24 (0.9%)	6 (0.7%)		5 (0.9%)		4 (0.9%)		9 (0.9%)
Past medical history											<0.01
None		2550 (92.6%)	775 (93.0%)		468 (88.5%)		398 (93.9%)		909 (93.9%)
Cardiovascular		119 (4.3%)	45 (5.4%)		28 (5.3%)		14 (3.3%)		32 (3.3%)
Respiratory		11 (0.4%)	1 (0.1%)		4 (0.8%)		3 (0.7%)		3 (0.3%)
Cerebrovascular		23 (0.8%)	6 (0.7%)		14 (2.6%)		2 (0.5%)		1 (0.1%)
Diabetes		12 (0.4%)	2 (0.2%)		3 (0.6%)		2 (0.5%)		5 (0.5%)
Malignancy		31 (1.1%)	2 (0.2%)		10 (1.9%)		4 (0.9%)		15 (1.5%)
Others (endocrine, etc.)		8 (0.3%)	2 (0.2%)		2 (0.4%)		1 (0.2%)		3 (0.3%)
Arrest place
Public		724 (26.3%)	37 (4.4%)		141 (26.7%)		153 (36.1%)		393 (40.6%)		<0.01
Private		1993 (72.4%)	790 (94.8%)		380 (71.8%)		257 (60.6%)		566 (58.5%)
Others		37 (1.3%)	6 (0.7%)		8 (1.5%)		14 (3.3%)		9 (0.9%)
Urbanization											0.51
Metropolitan		1104 (40.1%)	337 (40.5%)		208 (39.3%)		158 (37.3%)		401 (41.4%)
witnessed arrest		994 (36.1%)	223 (26.8%)		225 (42.5%)		193 (45.5%)		353 (36.5%)		<0.01
Bystander CPR											<0.01
None		1097 (39.8%)	242 (29.1%)		166 (31.4%)		163 (38.4%)		526 (54.3%)
Bystander CPR with dispatcher assistance		1232 (44.7%)	500 (60.0%)		280 (52.9%)		163 (38.4%)		289 (29.9%)
Bystander CPR without dispatcher assistance		425 (15.4%)	91 (10.9%)		83 (15.7%)		98 (23.1%)		153 (15.8%)
Dispatcher outcome
Cardiac arrest recognition		1694 (61.5%)	658 (79.0%)		350 (66.2%)		230 (54.2%)		456 (47.1%)		<0.01
DA-CPR instructed		1491 (54.1%)	616 (73.9%)		328 (62.0%)		193 (45.5%)		354 (36.6%)		<0.01
Call-to-DA-CPR instruction, sec, median (IQR)		107 (77,158)	101 (75,144)		108 (79,159)		116.00 (77,185)		114 (77,179)		<0.01
DA-CPR instructed within 120 s		832 (30.2%)	377 (45.3%)		184 (34.8%)		93 (21.9%)		178 (18.4%)		<0.01
DA-CPR instructed after 120 s		659 (23.9%)	239 (28.6%)		144 (27.2%)		100 (22.6%)		176 (18.2%)		<0.01
DA-CPR instructed within 180 s		1145 (41.6%)	506 (60.7%)		254 (48.0%)		132 (31.1%)		253 (26.1%)		<0.01
DA-CPR instructed after 180 s		346 (12.5%)	110 (13.2%)		74(14.0%)		61 (14.4%)		101 (10.5%)		<0.01
Initial ECG at scene
Shockable (Vf/VT)		229 (8.3%)	9 (1.1%)		26 (4.9%)		61 (14.4%)		133 (13.7%)		<0.01
EMS time interval, min
Response time interval, median (IQR)		6.00 (5.00, 9.00)	6.00 (5.00, 8.00)		7.00 (5.00, 9.00)		7.00 (5.00, 9.00)		7.00 (5.00, 9.00)		<0.01
Scene time interval, median (IQR)		9.00 (7.00, 13.00)	8.00 (6.00, 11.00)		9.00 (6.00, 12.00)		10.00 (7.00, 14.00)		10.00 (7.00, 15.00)		<0.01
Transport time interval, median (IQR)		6.50 (4.00, 10.00)	6.00 (4.00, 11.00)		7.00 (4.00, 11.00)		7.00 (4.00, 11.00)		6.00 (4.00, 10.00)		<0.01
Survival outcome
prehospital ROSC		265 (9.6%)	48 (5.8%)		37 (7.0%)		48 (11.3%)		132 (13.6%)		<0.01
Survival to discharge		282 (10.2%)	63 (7.6%)		50 (9.5%)		48 (11.3%)		121 (12.5%)		<0.01
Good Neurologic recovery (CPC 1-2)		158 (5.7%)	28 (3.4%)		17 (3.2%)		31 (7.3%)		82 (8.5%)		<0.01

SD, standard deviation; IQR, interquartile range; CPR, cardiopulmonary resuscitation; DA-CPR, dispatcher-assisted cardiopulmonary resuscitation; Vf, ventricular fibrillation; VT, ventric- ular tachycardia; CPC, cerebral performance category.

associated with decreased odds of cardiac arrest recognition when the cause of arrest was non-medical.

1. Discussion

In our retrospective analysis, pediatric age was associated with cardiac arrest recognition by emergency medical dispatchers. In particular, the 14-18 year old age group was associated with a decreased probability of all study outcomes (cardiac arrest recognition, DA-CPR instruction ini- tiated within 120 s, and bystander CPR at the scene). In the interaction analysis, the negative association between age and dispatcher perfor- mance was more prominent in pediatric OHCA patients with non- medical causes of arrest. Since DA-CPR is a major prognostic factor that

leads to bystander CPR, strategic approaches, such as protocol develop- ment and systematic case reviews to improve recognition, could be con- sidered for improvement of recognition outcome in this age group.

Recognition of cardiac arrest by dispatchers is influenced by multiple factors associated with callers, dispatchers, and patients [4,16,17]. Mo- tions during the initial phase of cardiac arrest, such as agonal breathing, gasping, and seizure-like movements, have been shown to act as bar- riers to accurate recognition by dispatchers [3,18]. Studies covering dis- patcher performance in adult OHCA showed that the median time interval from call to recognition was between 60 and 70 s and 176-211 s for call to DA-CPR [4,16]. In a retrospective analysis con- ducted in Singapore [4], the rate of dispatcher cardiac arrest recognition was 4% lower if there were one or more barriers to DA-CPR encountered

Table 2

Multivariable logistic regression analysis by age-group.

Outcome	Unadjusted			Adjusted?
	Odds ratio	95% CI		Odds ratio	95% CI

Cardiac arrest recognition by dispatcher

<1 year	1.00 (Reference)		1.00 (Reference)
1-6 years	0.52	0.41-0.66	0.81	0.61-1.08
7-13 years	0.32	0.24-0.41	0.55	0.41-0.74
14-18 years	0.24	0.19-0.29	0.44	0.34-0.57

DA-CPR instructed within 120 s

<1 year 1.00 (Reference) 1.00 (Reference)

1-6 years 0.65 0.52-0.81 0.92 0.71-1.18

7-13 years 0.34 0.26-0.44 0.51 0.38-0.69

14-18 years 0.27 0.22-0.34 0.45 0.35-0.58

Bystander CPR at scene

<1 year	1.00 (Reference)		1.00 (Reference)
1-6 years	0.90	0.71-1.13	1.09	0.83-1.42
7-13 years	0.66	0.51-0.84	0.80	0.60-1.06
14-18 years	0.34	0.28-0.41	0.47	0.37-0.60

CPR; cardiopulmonary resuscitation, DA-CPR; dispatcher-assisted cardiopulmonary resus- citation.

• Adjusted for cause of arrest (medical vs. non-medical), sex, presence of underlying

comorbidities, year, place of arrest, witness, initial ECG rhythm.

during the emergency call (94.9% vs. 99.0%, p < 0.01). In our multivari- able logistic regression modeling, cardiac arrest occurred at public place (AOR with 95% CI: 0.30 (0.24-0.37),private place as reference) was an impactful factor that negatively associated with dispatcher’s recogni- tion. Although we do not have information regarding the relationship between the caller and the patient, it might be due to different caller- patient relationship characteristics according to type of cardiac arrest places. Based on previous research, several strategic approaches and protocol developments have been reported to improve cardiac arrest recognition in dispatch centers [19,20]. Further research should also be considered regarding the evaluation of barriers against cardiac arrest recognition and strategy development for better recognition and performance of DA-CPR in pediatric OHCA, such as video-assistance systems [21].

Patients younger than one year old with medical causes comprise the largest population of pediatric OHCA patients. In this population, the proportion of bystander CPR and dispatcher performance measures was higher than in other age groups. The reason for the high recognition rate by dispatchers might be due to the high incidence rate and education regarding sudden death in patients younger than one year old [22-24].

Compared to the improved survival rate in adult OHCA [25], the sur- vival rate in pediatric OHCA did not significantly change over time [26]. Pediatric OHCA occurs less commonly than adult OHCA. Less than 5% of total OHCA occurs in the pediatric population in Korea [9] and perhaps, the statistics would be similar in other countries [26]. Therefore, EMS cli- nicians and emergency medical dispatchers, might not frequently en- counter pediatric OHCA, and the process might be less efficient and prompt due to unfamiliarity with pediatric OHCA. Additionally, in our analysis, the proportion of non-medical causes, especially the proportion of traumatic arrest, increased in the older age group of pediatric OHCA pa- tients. The development of a separate field algorithm for the recognition and management of pediatric Traumatic cardiac arrest has been suggested emphasizing simultaneous Life-saving interventions (ex>Hemorrhage control) other than CPR [27]. However, to our knowledge, no separate dis- patcher recognition algorithm has been reported for specific age groups and causes of OHCA in pediatric or adult populations.

Failure of EMD recognition as well as delay in provision of DA-CPR instruction during emergency call are associated with decreased sur- vival and neurologic outcome in OHCA [1,28]. Based on our study re- sults, local medical directors could consider evaluating characteristics and dispatcher performance in pediatric population according to age and presumed cause of arrest and might consider developing additional

Table 3

Multivariable logistic regression with interaction between age-group and cause of arrest.

Outcome Adjusted?

n/N (%) Odds ratio 95% CI Medical cause of cardiac arrest (N = 1469)

Cardiac arrest recognition by dispatcher

<1 year	547/694 (78.8%)	1.00 (Reference)
1-6 years	211/278 (75.9%)	0.91	0.63-1.30
7-13 years	134/208 (64.4%)	0.69	0.47-1.00
14-18 years	174/289 (60.2%)	0.65	0.46-0.93

DA-CPR instructed within 120 s

<1 year	314/694 (45.2%)	1.00 (Reference)
1-6 years	117/278 (42.1%)	0.97	0.71-1.31
7-13 years	65/208 (31.3%)	0.70	0.49-0.99
14-18 years	84/289 (29.1%)	0.67	0.48-0.95
Bystander CPR at EM <1 year	S arrival 500/694 (72.1%)	1.00 (Reference)
1-6 years	205/278 (73.7%)	0.97	0.70-1.35
7-13 years	154/208 (74.0%)	0.94	0.65-1.37
14-18 years	206/289 (71.3%)	0.75	0.53-1.05

Non-medical cause of cardiac arrest (N = 1285) Cardiac arrest recognition by dispatcher

<1 year	111/139 (78.9%)	1.00 (Reference)
1-6 years	139/251 (55.4%)	0.46	0.27-0.79
7-13 years	96/216 (44.4%)	0.29	0.17-0.50
14-18 years	282/679 (41.5%)	0.22	0.14-0.36
DA-CPR instructed <1 year	within 120 s 63/139 (45.3%)	1.00 (Reference)
1-6 years	67/251 (26.7%)	0.60	0.37-0.96
7-13 years	28/216 (13.0%)	0.23	0.13-0.40
14-18 years	94/679 (13.8%)	0.23	0.15-0.35
Bystander CPR at EMS arrival
<1 year	91/139 (65.5%)	1.00 (Reference)
1-6 years	158/251 (63.0%)	0.93	0.59-1.48
7-13 years	107/216 (49.5%)	0.55	0.34-0.87
14-18 years	236/679 (34.8%)	0.29	0.19-0.44

CPR; cardiopulmonary resuscitation, DA-CPR; dispatcher-assisted cardiopulmonary resus- citation.

• Adjusted for cause of arrest (medical vs. non-medical), sex, presence of underlying

comorbidities, year, place of arrest, witness, initial ECG rhythm.

protocols for the pediatric population, considering that recognition of cardiac arrest by emergency medical dispatchers is an important and key precedence factor for successful DA-CPR and favorable outcomes of pediatric OHCA.

• 1. Limitations

Our study has a few limitations. First, although we used five years of nationwide OHCA database, due to the retrospective observational na- ture of the study, the results of our study should be carefully interpreted. In systems with different dispatching systems and EMS protocols, the results of the analysis might differ slightly from our study. Second, the exact age and presumed cause of cardiac arrest used in the analysis were extracted from the medical review. In our current dispatch proto- col, the dispatcher should ask the caller about the age of the patient and the circumstances of the situation. However, even if the cardiac arrest protocol was subdivided according to age and presumed cause of arrest, sometimes it might be difficult for the dispatcher to identify the exact age and the presumed cause during the initial phase of the call taking and dispatching. Finally, our nationwide registry only included OHCA reported to 119 emergency calls; pediatric OHCAs who were brought to the hospital directly by their caregivers without activating the EMS system were not included in the database.

1. Conclusion

In OHCA occurring in the pediatric population, patients ages 7-18 years old were negatively associated with cardiac arrest recognition

by emergency medical dispatchers and DA-CPR instruction within opti- mal timeframes compared to those younger than one year old. The neg- ative association was prominent in all age groups equal to or older than one year old when the presumed cause of arrest was non-medical. The tailored dispatching protocol might be considered according to patient age and cause of arrest for better dispatcher performance in pediatric OHCA patients.

CRediT authorship contribution statement

Tae Han Kim: Conceptualization, Formal analysis, Visualization, Writing - original draft. Jin Hee Jung: Writing - review & editing, Super- vision, Methodology, Data curation, Conceptualization. Kyoung Jun Song: Data curation, Methodology, Supervision, Writing - review & editing. Ki Jeong Hong: Writing - review & editing, Methodology, Data curation. Joo Jeong: Data curation, Resources, Validation. Stephen Gyung Won Lee: Validation, Resources, Data curation.

Declaration of Competing Interest

There are no conflicts of interest for all authors in this study.

Acknowledgement

None.

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