Abstract
OBJECTIVE: We assessed out-of-hospital cardiac arrests (OHCAs) for various pediatric age groups.
METHODS: This prospective, population-based, observational study included all emergency medical service-treated OHCAs in Osaka, Japan, between 1999 and 2006 (excluding 2004). Patients were grouped as adults (>17 years), infants (<1 year), younger children (1–4 years), older children (5–12 years), and adolescents (13–17 years). The primary outcome measure was 1-month survival with favorable neurologic outcome.
RESULTS: Of 950 pediatric OHCAs, resuscitations were attempted for 875 patients (92%; 347 infants, 203 younger children, 135 older children, and 190 adolescents). The overall incidence of nontraumatic pediatric OHCAs was 7.3 cases per 100 000 person-years, compared with 64.7 cases per 100 000 person-years for adults and 65.5 cases per 100 000 person-years for infants. Most infant OHCAs occurred in homes (93%) and were not witnessed (90%). Adolescent OHCAs often occurred outside the home (45%), were witnessed by bystanders (37%), and had shockable rhythms (18%). One-month survival was more common after nontraumatic pediatric OHCAs than adult OHCAs (8% [56 of 740 patients] vs 5% [1677 of 33 091 patients]; adjusted odds ratio: 2.26 [95% confidence interval: 1.63–3.13]). One-month survival with favorable neurologic outcome was more common among children than adults (3% [21 of 740 patients] vs 2% [648 of 33 091 patients]; adjusted odds ratio: 2.46 [95% confidence interval: 1.45–4.18]). Rates of 1-month survival with favorable neurologic outcome were 1% for infants, 2% for younger children, 2% for older children, and 11% for adolescents.
CONCLUSION: Survival and favorable neurologic outcome at 1 month were more common after pediatric OHCAs than adult OHCAs.
WHAT'S KNOWN ON THIS SUBJECT:
Recent data indicate that pediatric out-of-hospital cardiac arrests (OHCAs) are not rare, and survival rates are greater than those for adults. However, it remains unclear whether children are more likely to survive with favorable neurologic outcomes after OHCAs.
WHAT THIS STUDY ADDS:
Pediatric patients with OHCAs had higher rates of survival with favorable neurologic outcomes than did adults. Outcomes and patient characteristics differed among age groups. This study's results suggest the importance of age-specific approaches to address this important public health problem.
Out-of-hospital cardiac arrest (OHCA) is a leading cause of death among adults in industrialized countries.1 Extensive emergency medical service (EMS) systems have focused on improving outcomes for this major public health problem. However, pediatric OHCAs have engendered relatively less public health interest, in part because they have been considered rare events with dismal outcomes.2
More-recent data indicated that pediatric OHCAs are not so rare and children are more likely to survive OHCAs than are adults.3,–,6 Importantly, those data did not include postresuscitation neurologic outcomes; therefore, it remains unclear whether children are more likely than adults to survive OHCAs with favorable neurologic outcomes.
The Utstein Osaka Project, which was launched in 1998, is a large, prospective, population-based, cohort study of OHCAs in Osaka, Japan, covering ∼8.8 million residents with 1.4 million children (<18 years of age).7,8 During the initial 7 years of this project, there were ∼1000 EMS-assessed pediatric OHCAs. This study aims to elucidate epidemiological features of these pediatric OHCAs. We hypothesized that (1) children would be more likely to experience neurologically favorable 1-month survival after nontraumatic OHCAs, compared with adults, and (2) the incidences, characteristics, and outcomes of OHCAs would differ among pediatric age groups.
METHODS
Study Design, Setting, and Population
This observational study enrolled all EMS-treated pediatric and adult patients who suffered OHCAs in Osaka Prefecture between January 1, 1999, and December 31, 2006. Patients from 2004 were excluded from analyses because of differences in data collected that year. Osaka has an area of 1892 km2 and both urban and rural communities. The population of Osaka in 2005 was 8 817 166, and 1 452 489 people (16%) were younger than 18 years.9
Cardiac arrest was defined as the cessation of cardiac mechanical activity, confirmed by the absence of signs of circulation.10 The arrest was presumed to be of cardiac origin unless it was caused by trauma, drowning (submersion), drug overdose, foreign-body asphyxia, exsanguination, or any other noncardiac causes, according to the Utstein-style international guidelines.10 These diagnoses were determined by the physician in charge in collaboration with the EMS rescuers. The research protocol was approved by the institutional review board of Osaka University, with the assent of the EMS authorities of the local governments in Osaka Prefecture.
EMS Systems in Osaka
In Osaka Prefecture, there were 34 fire stations with emergency dispatch centers in 2006. The EMS system is operated by the local fire stations. The most highly trained prehospital emergency care providers are emergency life-saving technicians, who are authorized to insert intravenous lines and adjunct airways and to use semiautomated external defibrillators for patients with OHCA. Specially trained emergency life-saving technicians were permitted to provide tracheal intubation for adults after July 2004 and to administer epinephrine intravenously for adults after April 2006.11 However, they are not supposed to provide either tracheal intubation or intravenously administered epinephrine for children. The use of automated external defibrillators by citizens was legally approved in July 2004.11 Do-not-resuscitate orders or living wills are not generally accepted in Japan, and EMS providers are not permitted to terminate resuscitation in the field.12,13 Therefore, all patients with OHCAs who were treated by EMS personnel were transported to a hospital and were registered in this study. Details of the EMS system in Osaka were described previously.14
Data Collection and Quality Control
Data were collected prospectively by using a form that included all core data recommended in the Utstein-style reporting guidelines for cardiac arrests.10 The initial rhythm was recorded and diagnosed by EMS personnel with semiautomated defibrillators on the scene and was confirmed by the physician who was responsible for online medical direction. The times of EMS call receipt and vehicle arrival at the scene were recorded automatically at the dispatch center. The times of collapse and initiation of bystander cardiopulmonary resuscitation (CPR) were obtained through EMS interviews with bystanders before departure from the scene. The time of defibrillation was recorded by the semiautomated defibrillator. Defibrillators were synchronized with the clock at the dispatch center, as were other relevant EMS time devices (eg, clocks and watches).
The data form was filled out by the EMS personnel in cooperation with the physicians in charge of the patient, transferred to the Osaka EMS Information Center, and then checked by the investigators. If the data sheet was incomplete, then the relevant EMS personnel were contacted and questioned and the data sheet was completed. All survivors were monitored for up to 1 month after the event by the EMS personnel and investigators, with the cooperation of the Osaka Medical Association and relevant local medical institutions.
Study End Points
Neurologic outcomes were assessed with the Glasgow-Pittsburgh Cerebral Performance Category scale (1 = good performance, 2 = moderate disability, 3 = severe cerebral disability, 4 = coma/vegetative state, and 5 = death).15 The primary end point was a favorable neurologic outcome 1 month after OHCA, which was defined prospectively as a Cerebral Performance Category scale score of 1 or 2 or no change in the Cerebral Performance Category scale score from the prearrest baseline score.16 Secondary outcome measures included return of spontaneous circulation, admission to the hospital, and 1-month survival.10
Statistical Analyses
Patient characteristics and outcomes were evaluated according to cause and age group. The cause of OHCA was initially categorized as traumatic or nontraumatic, and the latter category was subcategorized as cardiac, noncardiac (intracranial, respiratory, or other), injury (submersion, foreign-body asphyxia, hanging, drug overdose, or unknown), or unknown.12 Patients were categorized into 1 of the following pediatric age groups: infants (<1 year of age; n = 347); younger children (1–4 years of age; n = 203); older children (5–12 years of age; n = 135); and adolescents (13–17 years of age; n = 190). Adults were defined as older than 17 years (n = 35 140).4,8,16,–,18 The denominators for annual incidences of OHCA were derived from 2005 Japanese census data.9
Continuous variables were evaluated with unpaired t tests and categorical variables with χ2 tests. Multivariate logistic regression analyses were used to assess the factors associated with better neurologic outcomes. Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated. We adjusted for potential confounders including age, gender, location of arrest, activities of daily living before arrest, bystander-witnessed status, bystander CPR status, first documented rhythm, and time interval from the call to the initiation of CPR by EMS personnel. All of the tests were 2-tailed, and P values of <.05 were considered statistically significant. All statistical analyses were performed by using SPSS 16.0J (SPSS, Chicago, IL).
RESULTS
Overall Characteristics and Rates
During these 7 years, 950 pediatric OHCAs (subjects <18 years of age) were documented, and resuscitation was attempted by EMS personnel in 875 cases (92%). Figure 1 shows an overview of the EMS-treated pediatric OHCAs, with the outcomes, according to cause, witness status, and first documented rhythm. Of 740 OHCAs with nontraumatic causes (85%), 148 (20%) were witnessed by bystanders. Among the 740 nontraumatic OHCAs, the first documented rhythms were ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) in 27 cases (4%), pulseless electrical activity (PEA) in 91 cases (12%), and asystole in 591 cases (80%). Among the traumatic OHCAs, 69 (51%) were witnessed by bystanders; the first documented rhythms were VF/VT in 6 cases (4%), PEA in 41 cases (30%), and asystole in 81 cases (60%).
Utstein enrollment and outcomes of pediatric OHCAs. ROSC indicates return of spontaneous circulation; Hosp Adm, hospital admission; Good Neuro, good neurologic outcome.
Among patients with nontraumatic OHCAs, rates of 1-month survival with neurologically favorable outcomes after VF/VT, PEA, and asystole were 19%, 10%, and 1%, respectively. Among patients with traumatic OHCAs, only 1 (1%) survived with a neurologically favorable outcome. Among 875 eligible victims, we could not obtain data on gender for 2 (<1%), witnessed status for 6 (1%), bystander CPR for 17 (2%), cause for 5 (1%), first documented rhythm for 38 (4%), return of spontaneous circulation for 6 (1%), 1-month survival for 17 (2%), and neurologic outcome for 1 (<1%). For OHCAs with a nontraumatic cause, we could not obtain detailed information on cause for 5 victims.
Event Characteristics According to Age Group
The mean annual, population-based, incidence rates of EMS-treated OHCAs (traumatic and nontraumatic) according to age group are shown in Table 1. The overall annual incidence rate for pediatric OHCAs was 8.6 cases per 100 000 person-years (95% CI: 7.6–9.6 cases per 100 000 person-years), and the overall annual incidence rate for adult OHCAs was 68.7 cases per 100 000 person-years (95% CI: 64.0–73.4 cases per 100 000 person-years). The pediatric and adult annual incidence rates of nontraumatic OHCAs were 7.3 cases per 100 000 person-years (95% CI: 6.4–8.2 cases per 100 000 person-years) and 64.7 cases per 100 000 person-years (95% CI: 60.2–69.2 cases per 100 000 person-years), respectively. The incidences of nontraumatic OHCAs were 65.5 cases per 100 000 person-years (95% CI: 55.1–75.9 cases per 100 000 person-years) among infants, 7.7 cases per 100 000 person-years (95% CI: 6.1–9.3 cases per 100 000 person-years) among younger children, 2.5 cases per 100 000 person-years (95% CI: 2.1–3.0 cases per 100 000 person-years) among older children, and 3.9 cases per 100 000 person-years (95% CI: 3.4–4.4 cases per 100 000 person-years) among adolescents.
Incidence Rates of OHCAs According to Age Group
Table 2 shows the causes of EMS-treated OHCAs according to age group. Overall, pediatric victims had a significantly smaller proportion of OHCAs with presumed cardiac causes, compared with adults (30% vs 58%; OR: 0.53 [95% CI: 0.48–0.58]). The proportions of OHCAs with presumed cardiac causes were 34% for infants, 31% for younger children, 30% for older children, and 25% for adolescents. The proportions of OHCAs attributable to respiratory causes, submersion, or foreign-body asphyxia (ie, all primary respiratory arrest–precipitated cardiac arrests) were greater among children than among adults (30% vs 16%; OR: 1.86 [95% CI: 1.67–2.06]). The proportions of pediatric OHCAs precipitated by respiratory arrest were 36% for infants, 35% for younger children, 29% for older children, and 14% for adolescents.
Causes of OHCAs According to Age Group
Patient Characteristics
Characteristics of patients with OHCAs with nontraumatic causes, according to age group, are presented in Table 3. For all pediatric age ranges (0–17 years), 59% (436 of 740 cases) of nontraumatic OHCAs occurred in boys. Most infants suffered OHCAs at home (93%) and without witnesses (90%). Adolescent OHCAs often occurred out of the home (45%), often were witnessed by bystanders (37%), and had VF/VT as the first documented rhythm in 18% of cases. Bystander CPR was provided for 41% of pediatric OHCAs, compared with 28% of adult OHCAs (OR: 1.85 [95% CI: 1.59–2.14]).
Characteristics of Nontraumatic OHCAs According to Age Group
Survival Outcomes
Outcomes after nontraumatic OHCAs, according to age group and first documented rhythm, are shown in Table 4. Overall 1-month survival after nontraumatic OHCA was more common among children than among adults (8% [56 of 740 patients] vs 5% [1677 of 33 091 patients]; unadjusted OR: 1.48 [95% CI: 1.15–1.91]; adjusted OR: 2.26 [95% CI: 1.63–3.13]). One-month survival rates after nontraumatic OHCAs were 5% for infants, 9% for younger children, 7% for older children, and 14% for adolescents. Neurologically favorable 1-month survival also was more common among children, compared with adults (3% [21 of 740 patients] vs 2% [648 of 33 091 patients]; unadjusted OR: 1.46 [95% CI: 0.94–2.28]; adjusted OR: 2.46 [95% CI: 1.45–4.18]). Neurologically favorable 1-month survival rates after nontraumatic OHCAs were 1% for infants, 2% for younger children, 2% for older children, and 11% for adolescents. Among 56 patients who survived 1 month, 21 (38%) survived with favorable neurologic outcomes.
Outcomes After Nontraumatic OHCAs According to Age Group and First Documented Rhythm
The rates of 1-month survival with neurologically favorable outcomes after VF were 19% (5 of 27 patients) among all children and 11% (285 of 2529 patients) among adults (unadjusted OR: 1.79 [95% CI: 0.67–4.76]). The rate of neurologically favorable 1-month survival after PEA was higher among all children than among adults (10% [9 of 91 patients] vs 3% [211 of 6241 patients]; unadjusted OR: 3.14 [95% CI: 1.56–6.33]). The rates of neurologically favorable 1-month survival after PEA for infants, younger children, older children, and adolescents were 6%, 12%, 5%, and 27%, respectively.
Table 5 shows adjusted ORs and their 95% CIs for neurologically favorable outcomes after nontraumatic OHCAs. Adolescents were more likely to have favorable neurologic outcomes than were adults (11% vs 2%; adjusted OR: 5.44 [95% CI: 2.55–11.58]). In contrast, the rates of favorable neurologic outcomes among infants, younger children, and older children were not demonstrably different from the frequency among adults. Favorable neurologic outcomes were associated with VF/VT in comparison with asystole (adjusted OR: 14.51 [95% CI: 11.09–19.00]), PEA in comparison with asystole (adjusted OR: 4.43 [95% CI: 3.40–5.76]), and shorter time to CPR by EMS personnel (adjusted OR for 1-minute increase: 0.81 [95% CI: 0.78–0.84]).
Factors Contributing to Neurologically Favorable Outcomes After Nontraumatic OHCAs
DISCUSSION
This large-scale, population-based, cohort study establishes that pediatric victims of OHCAs had higher survival rates and higher rates of survival with favorable neurologic outcomes 1 month after resuscitation, compared with adults. In addition, epidemiological characteristics and outcomes for pediatric OHCAs differed according to age group. In particular, only adolescents had better outcomes than adults.
Among adolescents, 45% of OHCAs occurred outside the home, 46% were witnessed, and 18% had VF as the first documented rhythm. Favorable neurologic outcomes were most common in this age group, compared with younger age groups or adults. Interestingly, adolescents were more likely to survive with neurologically favorable outcomes, compared with other age groups, irrespective of the initial rhythm. The adjusted OR for survival with a neurologically favorable outcome for adolescents was 5.4 times that for adults, with controlling for other potentially confounding factors including initial rhythm. Perhaps adolescents are physiologically more fit for survival after OHCAs, as suggested by Herlitz et al.4
Consistent with many previous studies, outcomes after OHCAs were poor for infants.5,13,19 Only 8% of infant OHCAs were witnessed by bystanders, and presumably many of the unwitnessed arrests were attributable to sudden infant death syndrome (SIDS).20 Notably, previous investigations showed that one-third to one-half of cardiac arrests among infants are attributable to SIDS.21,22 Because children with SIDS typically have had no blood flow for a prolonged time before a parent realizes that the infant is experiencing cardiac arrest, it is not surprising that the outcomes are so poor. It was reported that outcomes after in-hospital cardiac arrests were better among infants and younger children, compared with older children and adults.23 Those authors speculated that infants might have superior CPR hemodynamics because of better transmission of chest compression forces through their more-compliant chest walls. In contrast to infants with OHCAs, 83% of infants with in-hospital cardiac arrests were being observed and monitored. Therefore, the infants with in-hospital cardiac arrests could receive CPR promptly, with superior hemodynamics and with resultant return of spontaneous circulation, whereas infants with OHCAs usually do not have the same opportunity. Not surprisingly, a proactive prevention campaign24,–,27 is more important than advanced life support programs for reducing mortality rates in this age group.22
As expected, we observed different incidence patterns of OHCAs among the different age groups. The incidence was much higher among infants than among younger children, older children, and adolescents. Interestingly, the incidence among infants was similar to the incidence among adults, consistent with previous reports.5 The population-based annual incidences of nontraumatic pediatric OHCAs in Osaka (7.3 cases per 100 000 person-years for 0- to 17-year-old patients and 65.5 cases per 100 000 person-years for infants) were quite similar to those in North America (8.0 cases per 100 000 person-years for 0- to 19-year-old patients and 72.7 cases per 100 000 person-years for infants).5 In contrast, the annual incidence of adult cardiac arrests in North America (126.5 cases per 100 000 person-years)5 was almost double that in Osaka (64.7 cases per 100 000 person-years). These differences in annual incidences among adults might be explained by differences in lifestyle and environmental factors.28
An important finding is that the rates of survival with favorable neurologic outcomes in the present study were quite low for all pediatric and adult age groups except adolescents. There are some possible explanations for these poor outcomes. Overall, 76% of these nontraumatic pediatric OHCAs were not witnessed and only 4% had shockable rhythms. In addition, the Japanese emergency physicians, nurses, and EMS personnel had limited pediatric training, equipment, and experience. Furthermore, regionalized care for critically ill children was, and is, lacking and most children with OHCAs were sent to adult tertiary emergency facilities29 or hospitals with relatively small pediatric services, without a PICU.30 With greater national emphasis on the recognition and treatment of OHCAs, increased attention to lay CPR training, the addition of telephone dispatcher assistance with CPR, superior EMS basic and advanced life support training for OHCAs,27 and improvements in postarrest care,31 outcomes of adult OHCAs have improved over the past several years.8,14 Perhaps improvements in outcomes also are occurring for pediatric OHCAs, although the small number of pediatric OHCAs precludes meaningful year-by-year analysis. Nevertheless, outcomes after pediatric OHCAs were better than adult outcomes.
An important limitation of this study is that we enrolled only children who were noted by EMS providers to have an absence of signs of circulation. Animal and clinical investigations of pediatric OHCAs indicated that CPR could be quite effective when provided promptly by a simulated bystander and return of spontaneous circulation might occur within a few minutes (ie, before the EMS personnel would arrive).2,32,33 Such pediatric OHCAs with potentially good outcomes would have been excluded from this study. Therefore, it is likely that the incidence of pediatric OHCAs in this population was actually higher and the outcomes were better than documented in this investigation.
This observational study has several other limitations. We were able to evaluate neurologic status only at 1 month after the OHCA, because longer follow-up data were not available. It is possible that neurologic status might have improved over time for some children. Furthermore, the Glasgow-Pittsburgh Cerebral Performance Category scale available in our data collection system was derived for adults and may be less useful for infants and children. In addition, the category of presumed cardiac cause of arrest is a diagnosis of exclusion (ie, there was simply no evidence of a noncardiac cause), according to the international Utstein-style guidelines for cardiac arrest data reporting. For children, the presumption that cardiac arrests with an undiagnosed cause should be attributed to a cardiac cause may be problematic. For example, infants with SIDS might be included in the cardiac group. Nevertheless, we used this classification system because it is the consensus, international, Utstein-style classification system in the literature.5,7,10,12,15,17 As with all observational studies, data integrity, validity, and ascertainment bias are potential limitations. The use of uniform data collection on the basis of Utstein-style guidelines for reporting of cardiac arrests, the large sample size, and the population-based design were intended to minimize these potential sources of biases.
CONCLUSIONS
In this study, children had better 1-month survival rates and better neurologic outcomes, compared with adults, after OHCAs. In addition, patient characteristics and outcomes of pediatric OHCAs differed among age groups. Age-specific approaches should be considered to reduce the rates of deaths attributable to OHCAs among children.
ACKNOWLEDGMENTS
This study was supported by a grant for emergency management scientific research from the Fire and Disaster Management Agency.
We are grateful to Takashi Kawamura, Yasuhisa Nishimoto, Toshimasa Hayashi, Akira Nishisaki, and Naohisa Kawamura for their advice and expertise. We greatly appreciate Hisashi Ikeuchi, Hidekazu Yukioka, Hisashi Sugimoto, Toshifumi Uejima, Kikushi Katsurada, Masafumi Kishimoto, Chizuka Shiokawa, Akihiko Hirakawa, Tokihiko Yamamoto, Hiroshi Rinka, Kentaro Kajino, Yasuo Ohishi, Ryusuke Kawaguchi, Kazuhisa Okuda, Hiroyuki Yokoyama, Tomohiko Sakai, Kayo Tanigawa, Chika Nishiyama, Sumito Hayashida, Yasuyuki Matsui, Kenichi Matsumura, and the other members of the Utstein Osaka Project for their contributions in organization, coordination, and oversight as a steering committee. We also are deeply indebted to the all of the EMS personnel and concerned physicians in Osaka Prefecture and the Osaka Medical Association for their indispensable cooperation and support.
Footnotes
- Accepted June 8, 2011.
- Address correspondence to Masahiko Nitta, MD, PhD, Department of Emergency Medicine, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki City, Osaka 569-8686, Japan. E-mail: nittam{at}poh.osaka-med.ac.jp
FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.
-
- OHCA —
- out-of-hospital cardiac arrest
- EMS —
- emergency medical service
- CPR —
- cardiopulmonary resuscitation
- VF —
- ventricular fibrillation
- PEA —
- pulseless electrical activity
- CI —
- confidence interval
- OR —
- odds ratio
- VT —
- ventricular tachycardia
- SIDS —
- sudden infant death syndrome
REFERENCES
- Copyright © 2011 by the American Academy of Pediatrics
In this issue
Jump to section
Related Articles
Cited By...
- Association of school hours with outcomes of out-of-hospital cardiac arrest in schoolchildren
- Can real-time feedback improve the simulated infant cardiopulmonary resuscitation performance of basic life support and lay rescuers?
- Dissemination of Chest Compression-Only Cardiopulmonary Resuscitation and Survival After Out-of-Hospital Cardiac Arrest
- Epidemiology and outcome of adult out-of-hospital cardiac arrest of non-cardiac origin in Osaka: a population-based study
- Outcomes of Out-of-Hospital Cardiac Arrest by Public Location in the Public-Access Defibrillation Era
- Factors associated with the clinical outcomes of paediatric out-of-hospital cardiac arrest in Japan
- Chest Compression-Only Cardiopulmonary Resuscitation for Out-of-Hospital Cardiac Arrest With Public-Access Defibrillation: A Nationwide Cohort Study
- Nationwide Improvements in Survival From Out-of-Hospital Cardiac Arrest in Japan
- Cardiac Arrest in Children and Young Adults: We Are Making Progress
- Relationship Between Arterial Partial Oxygen Pressure After Resuscitation From Cardiac Arrest and Mortality in Children
- Pediatric Out-of-Hospital Cardiac Arrest