Outcomes After In-Hospital Cardiac Arrest in Children With Cardiac DiseaseClinical Perspective
A Report From Get With the Guidelines–Resuscitation
Background—Small studies suggest that children experiencing a cardiac arrest after undergoing cardiac surgery have better outcomes than other groups of patients, but the survival outcomes and periarrest variables of cardiac and noncardiac pediatric patients have not been compared.
Methods and Results—All cardiac arrests in patients <18 years of age were identified from Get With the Guidelines–Resuscitation from 2000 to 2008. Cardiac arrests occurring in the neonatal intensive care unit were excluded. Of 3323 index cardiac arrests, 19% occurred in surgical-cardiac, 17% in medical-cardiac, and 64% in noncardiac (trauma, surgical-noncardiac, and medical-noncardiac) patients. Survival to hospital discharge was significantly higher in the surgical-cardiac group (37%) compared with the medical-cardiac group (28%; adjusted odds ratio, 1.8; 95% confidence interval, 1.3–2.5) and the noncardiac group (23%; adjusted odds ratio, 1.8; 95% confidence interval, 1.4–2.4). Those in the cardiac groups were younger and less likely to have preexisting noncardiac organ dysfunction, but were more likely to have ventricular arrhythmias as their first pulseless rhythm, to be monitored and hospitalized in the intensive care unit at the time of cardiac arrest, and to have extracorporeal cardiopulmonary resuscitation compared with those in the noncardiac group. There was no survival advantage for patients in the medical-cardiac group compared with those in the noncardiac group when adjusted for periarrest variables.
Conclusion—Children with surgical-cardiac disease have significantly better survival to hospital discharge after an in-hospital cardiac arrest compared with children with medical-cardiac disease and noncardiac disease.
Children with underlying cardiac disease are at a greater risk of experiencing a cardiac arrest compared with those without a cardiac diagnosis. Although the incidence of cardiac arrest in pediatric intensive care units (ICUs) is <2%,1–3 a report from a specialized pediatric cardiac ICU found a rate of arrest of 4%.4 Cardiac surgery confers an even greater risk, with cardiac arrest occurring in 6% of infants in the postoperative period.5
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Survival after an in-hospital cardiac arrest is poor, with only a quarter of pediatric patients surviving to hospital discharge.6 No large outcome studies specific to pediatric cardiac patients exist, although survival to hospital discharge in smaller series varies between 19% and 42%.4,5,7 This wide variability in outcomes is typical of single-institution studies because different centers have various levels of acuity and there are differences in definitions used and data collection methods.
The American Heart Association's Get With the Guidelines–Resuscitation (GWTG-R) (formerly the National Registry of Cardiopulmonary Resuscitation) is a large multicenter database of in-hospital cardiac arrests with standardized definitions and data reporting methodology.8 The purpose of this study was to use GWTG-R data to evaluate outcomes after in-hospital cardiac arrest in children with cardiac disease and to study factors associated with survival to hospital discharge. We hypothesize that children who have undergone cardiac surgery during the same admission as their cardiac arrest have better outcomes after in-hospital cardiac arrest compared with children with medical-cardiac disease and those with noncardiac disease.
Design and Setting
GWTG-R is sponsored by the American Heart Association and is the only national registry of in-hospital resuscitation events. The primary purpose of GWTG-R is quality improvement, and all data are deidentified in compliance with the Health Insurance Portability and Accountability Act. Participating hospitals are not required to obtain Institutional Review Board approval, although this study was approved by the Institutional Review Board of the University of Arkansas for Medical Sciences. GWTG-R uses a standardized form to report patient characteristics and conditions, details of the resuscitation event, processes of care, and outcomes.
All adult patients, pediatric patients, employees, and visitors who have a resuscitation event in a hospital facility are eligible for inclusion in the registry. There are 6 categories of data collected: (1) facility data, (2) patient demographic data, (3) pre-event data, (4) event data, (5) outcome data, and (6) quality improvement data. Explicit definitions have been generated for every data element. The registry is based on the Utstein-style template, which was developed to help standardize the collection and review of resuscitation data.9 The GWTG-R process for data collection and integrity has been described in detail previously.6,10,11
Inclusion and Exclusion Criteria
All children <18 years of age having an in-hospital cardiac arrest were eligible for inclusion in this study. Cardiac arrest was defined as the cessation of cardiac mechanical activity with the absence of palpable central pulse, apnea, and unresponsiveness. Subjects were excluded if resuscitation began outside a hospital, involved a newborn in the delivery room, occurred in the neonatal ICU, involved an obstetrics patient, or was limited to a shock by an implanted defibrillator or if the cardiac arrest was in an inpatient with a do not resuscitate order. For patients having multiple qualifying events during a single admission, only the first pulseless cardiac arrest (index event) was included in the analysis.
All patients included in the registry are categorized into 1 of 8 illness categories by the reporting hospital: medical-cardiac, medical-noncardiac, surgical-cardiac, surgical-noncardiac, newborn, obstetric, trauma, and other (visitor/employee). Newborn, obstetric, and other were excluded. All medical-noncardiac, surgical-noncardiac, and trauma patients were included in the noncardiac group for this study. Surgical-cardiac patients are defined as patients who are postoperative from cardiac surgery occurring during the same hospital admission as the cardiac arrest. Medical-cardiac patients are defined as patients whose primary diagnosis is a medical illness that is cardiovascular in origin. This group includes patients who are admitted for congenital heart disease but are not postoperative at the time of their cardiac arrest. Medical-noncardiac patients are defined as patients with a primary diagnosis of medical illness at the time of the event that is not cardiovascular. Surgical-noncardiac patients are defined as patients who are preoperative or postoperative with a surgical illness as the primary diagnosis that is not cardiac surgery at the time of the event. The last 2 groups include patients with underlying cardiac disease who are admitted for noncardiac medical or surgical illnesses.
Primary outcome was survival to hospital discharge. Secondary outcome measures included return of circulation with no need for chest compressions for >20 minutes, 24-hour survival, and neurological outcome. Patients whose resuscitation ended after being placed on cardiopulmonary bypass or extracorporeal cardiopulmonary resuscitation (ECPR) were considered to have return of circulation according to GWTG-R definition. Neurological outcome was assessed at discharge with the Pediatric Cerebral Performance Category scale,11 which divides outcome into the following 6 categories: (1) normal age-appropriate neurodevelopmental function, (2) mild disability, (3) moderate disability, (4) severe disability, (5) coma or vegetative state, and (6) brain death. Good neurological outcome was defined as a score of 1, 2, or 3 or no change from admission Pediatric Cerebral Performance Category.
Select hospital characteristics, patient demographic data, prearrest data, and resuscitation characteristics were compared between surgical-cardiac, medical-cardiac, and noncardiac disease groups. The χ2 test or Fisher exact test was used to analyze associations between disease groups and categorical variables, depending on the sparseness of the data. For continuous variables, the Kruskal-Wallis test was used. Wilcoxon rank-sum tests were used to make comparisons between pairs of disease categories. A Bonferroni correction was made to the P values to adjust for the 3 group comparisons made for each characteristic. All P values are 2 sided; the significance level was set at 0.05.
Multivariable logistic regression models were used to examine the association of independent variables on survival to hospital discharge. Factors were separated into prearrest and arrest factors, and separate models were fit to each type within each disease group. A complete list of variables can be found in Tables 1 and 2. Backward variable selection was used to eliminate prearrest or postarrest factors not significant at P=0.5 with era and hospital characteristics forced into the model. Variables missing >20% of the values were excluded. A linear time effect was included in each model to adjust for changes in survival over time. Duration of cardiopulmonary resuscitation (CPR) event was parameterized with a log transformation. A log base 2 was used so that the interpretation of the odds ratios for CPR duration is such that for each doubling of CPR duration, the odds of death in the hospital decrease by the estimate of the odds ratio. Model performance was assessed by the area under the receiver-operator characteristic curve (discrimination) and the Hosmer-Lemeshow goodness-of-fit statistic (calibration). Statistical analyses were performed with Stata 11.0 MP-Parallel Edition (StataCorp LP, College Station, TX). Odds of survival to hospital discharge were adjusted for all variables retained in multivariable analysis. To validate multivariate results, missing values were imputed and models were rerun with the Harrell method with the rms package in r software (http://.biostat.mc.vanderbilt.edu/rms).
From January 2000 to August 2008, 3323 index pulseless pediatric in-hospital cardiac arrests were documented among the illness categories of interest at 265 institutions. Of these, 640 (19%) were classified as surgical-cardiac, 574 (17%) as medical-cardiac, and 2109 (64%) as noncardiac.
The prearrest and arrest characteristics of the 3 groups are presented in Tables 1 and 2, respectively. Patients in the cardiac groups were significantly younger than those in the noncardiac group, with surgical-cardiac patients being younger than medical-cardiac patients. Cardiac arrests among the surgical-cardiac patients were more likely to occur in an ICU setting. The cardiac groups had less preexisting organ dysfunction, including fewer central nervous system abnormalities, less hepatic insufficiency, less diabetes mellitus, less trauma, less malignancy, fewer metabolic abnormalities, and less sepsis. Renal insufficiency was not different among groups. As would be expected, both cardiac groups had higher rates of preexisting arrhythmias and congestive heart failure.
Patients in the surgical-cardiac group had more intensive monitoring and more interventions before arrest compared with those in the medical-cardiac and noncardiac groups. They were also more likely to have vascular access in place, an arterial catheter, ECG monitoring, mechanical ventilation, and pacemakers and to be receiving vasoactive infusions compared with the other groups.
Cardiac arrests among patients in the surgical and medical-cardiac groups were more likely to be the result of arrhythmias or hypotension, whereas those in the noncardiac group were more likely to be precipitated by respiratory difficulties. Patients in both the surgical-cardiac and medical-cardiac groups were significantly more likely to have ventricular arrhythmias as their first observed pulseless rhythm; CPR duration was significantly longer and extracorporeal support was used more often compared with the noncardiac group.
Outcomes are presented in Table 3. Survival to hospital discharge was 37% in the surgical-cardiac group compared with 28% in the medical-cardiac group (adjusted odds ratio, 1.8; 95% confidence interval, 1.3–2.5; P<0.001) and 23% in the noncardiac group (adjusted odds ratio, 1.8; 95% confidence interval, 1.4–2.4; P<0.001). Surgical-cardiac patients were more likely to have return of circulation and to be alive after 24 hours after CPR. There was no difference in return of circulation between the medical-cardiac and noncardiac groups (53%); however, the medical-cardiac group was more likely to be discharged alive (P=0.022). After adjustment for other variables associated with outcome, there was no survival advantage for medical-cardiac patients compared with noncardiac patients. There was no difference in neurological outcome among survivors among the 3 groups. Year of arrest did not affect outcome in any group.
A total of 626 patients (19%) had multiple cardiac arrests during their hospital admission. There was no difference between the 3 groups in likelihood of multiple events. Survival to hospital discharge after >1 cardiac arrest was 29% for the surgical-cardiac group, 20% for the medical-cardiac group, and 17% for the noncardiac group.
Two separate multivariate logistic regression models were developed for each disease group: 1 to evaluate prearrest variables and 1 to evaluate arrest variables. The multivariate models for the surgical-cardiac and medical-cardiac groups are shown in Table 4 (prearrest variables) and Table 5 (arrest variables).
For the surgical-cardiac group, preexisting renal insufficiency, congestive heart failure, <300 facility beds, arrest in a teaching hospital, and CPR duration were associated with decreased odds of survival. ECPR and age >28 days were associated with improved survival in multivariate analysis. For the medical-cardiac group, a cardiac arrest occurring in the emergency department rather than the ICU, metabolic or electrotype abnormalities as the cause of the arrest, use of atropine during CPR, and CPR duration were associated with decreased odds of survival. Airway compromise as the immediate cause of the cardiac arrest, preexisting arrhythmia, and ECPR significantly improved the odds of survival in the medical-cardiac group. Results for these models negligibly changed when validated with the Harrell method.
Our analysis of this large multicenter database found significantly improved hospital survival after resuscitation from an in-hospital cardiac arrest in children who have undergone cardiac surgery compared with children without cardiac disease. Among the cardiac patients, the survival to hospital discharge of surgical-cardiac patients was significantly higher compared with patients with medical-cardiac disease. Better outcomes in this patient population may be related to multiple prearrest and postarrest characteristics.
These data confirm the findings of previous single-institution studies that have reported survival among pediatric postoperative cardiac patients after cardiac arrest requiring CPR to be as high as 42%.4,5 This is in contrast to more dismal (22% to 27%) survival after cardiac arrest among more heterogeneous pediatric populations.6,10 These reports are limited by their retrospective study design and small sample size (<100 subjects).4,5,7 GWTG-R size and use of standardized definitions and reporting improve on many of the limitations of these studies.
Our study highlights the characteristics unique to the cardiac population that may influence their post–cardiac arrest survival. In contrast to noncardiac patients, patients with cardiac disease were younger, had fewer preexisting conditions, and had increased monitoring and interventions at the time of cardiac arrest. Factors precipitating cardiac arrest and the type of cardiac rhythm present at the onset of the arrest in these patients are different from those found in noncardiac patients. Furthermore, resuscitative measures like the deployment of extracorporeal support are also far more likely to occur among cardiac patients.
Among the prearrest variables, the patient's age in particular may have important clinical implications on survival. In the surgical-cardiac group, more than three quarters of cardiac arrests occurred in infants <1 year of age compared with one half among the medical-cardiac patients and one third among the noncardiac patients. Among surgical-cardiac patients, neonates (<28 days of age) had worse survival to hospital discharge compared with older infants. Infants undergo more complex cardiac surgeries and thus are at a greater risk of postoperative cardiac arrest and mortality.7 These results are similar to those found by Meaney et al,10 who analyzed pediatric ICU arrests reported to GWTG-R and found that newborns (<1 month of age) had a lower hospital survival compared with infants (1 month–1 year of age), but both groups had significantly better survival compared with older children (> 1 year of age). They speculated that infants have better hemodynamics and perfusion during CPR as a result of their more compliant chest walls. Newborns and infants differ from older children in many other characteristics, and GWTG-R does not collect hemodynamic data, so it is not possible to assess other causes that may explain the differences in survival among age groups from this database.
Differences in the types of preexisting medical conditions may also have contributed to differences in hospital survival. For example, a history of trauma and malignancy, seen in 19% and 8% of noncardiac patients, respectively, are known to negatively affect survival,3 but are rare in patients with cardiac disease and thus have negligible impact on their overall survival. Furthermore, as indicated by our study, children requiring cardiac surgery are less likely to have multiple organ dysfunction and had lower rates of preexisting central nervous system dysfunction, liver dysfunction, diabetes mellitus, and sepsis. In a review of all pediatric ICU arrests, de Mos et al1 found that the number of dysfunctional organs before arrest was associated with hospital mortality.
Not surprisingly, surgical-cardiac patients had a greater number of interventions in place before their arrest, including venous and arterial access, mechanical ventilation, and cardiac monitoring, which may improve survival. Previous reports indicate that patients who have a cardiac arrest in a monitored setting or an arrest that is witnessed have improved survival.12 It is possible that early detection of life-threatening arrhythmias or hypotension secondary to enhanced monitoring may have improved outcomes despite a longer duration of CPR in cardiac patients.
Differences between the groups in the type of first observed pulseless rhythm before onset of CPR may also have contributed to the variation in survival. Pulseless electric activity was the most common rhythm among the surgical-cardiac group, whereas asystole was more common among the medical-cardiac and noncardiac groups. Children with pulseless electric activity as the first observed pulseless rhythm have been found to have better survival compared with those with asystole.6 Some patients with pulseless electric activity may in fact have some pulsatile blood flow despite having no palpable pulses, which may result in better outcomes than seen with asystole and complete absence of flow.
Children in the surgical-cardiac and medical-cardiac groups were more likely to have pulseless ventricular rhythms than those in the noncardiac group. The association between ventricular arrhythmias and improved survival is well documented in adults,13 and similar findings have been published in children.6,14 This improved survival is most likely related in part to these rhythms being more amenable to electric conversion. These data suggest that even though shockable rhythms are much less common among pediatric patients, early analysis of rhythm is important in pediatric CPR to identify patients who may benefit from timely defibrillation that could affect survival.
Extracorporeal Cardiopulmonary Resuscitation
In this study, we found that the use of ECPR was associated with improved survival in both cardiac groups. Prolonged duration of CPR is associated with dismal outcomes, and resuscitation beyond 30 minutes has been considered futile in the recent past.15 However, with the availability of rapid deployment of extracorporeal support during CPR, survival with intact neurological function has been reported even with prolonged CPR durations.16,17 A recent report from GWTG-R found that children with cardiac disease were more likely to survive to hospital discharge compared with children without cardiac disease when ECPR was used.18 The improved survival in patients with cardiac disease may be explained in part by the fact that these patients are more likely to be cared for at specialized centers with more intensive monitoring and the ability to deploy ECPR effectively.
The limitations of our study are similar to those seen in all studies using large multicenter databases. Analysis of the data may be limited by data integrity and validation issues at the multiple sites submitting data to the registry. The rigorous abstractor training and certification process, uniform data collection, consistent definitions, scientific advisory board reabstraction process, and large sample size, unique to GWTG-R, are intended to minimize these sources of study bias. Participation in GWTG-R is voluntary; nearly 15% of the hospitals in the United States are represented in this database. It is possible that outcomes may be different at nonparticipating institutions, and this report does not reflect outcomes in those institutions. Much of these data were collected before the 2005 release of new American Heart Association CPR guidelines,19 which emphasized the quality of chest compressions; recent studies have suggested improved outcomes with the implementation of these guidelines.20,21
Another limitation is related to the heterogeneity of clinical diagnoses that constitute the 3 illness categories studied. The surgical-cardiac group includes patients undergoing simple repairs who do not require cardiopulmonary bypass and neonates undergoing palliation of complex congenital heart defects. Survival between these groups may be vastly different.22,23 Differences in diagnosis may confound our analysis of facility data because more complex surgical patients will likely be cared for in children's hospitals and teaching hospitals that also have ECPR capabilities. GWTG-R is limited in this regard in that it does not provide specific information about diagnosis, so differences between cardiac subgroups cannot be elicited from this database. Data on individual institution use of ECPR were not available. GWTG-R does not collect data on whether patients later go on to require heart transplantation after ECPR, which may influence outcomes for cardiac patients. In addition, it is possible that children who are distant from surgery but are still hospitalized could be classified into either the medical or surgical-cardiac illness categories, confounding the analysis. Neonates with cardiac disease who were managed in the neonatal ICU are not included in this study because their resuscitation data were initially excluded by GWTG-R. Excluding these infants may bias our results because the youngest patients had lower odds of survival. Furthermore, other variables beyond those collected as part of the registry such as patient physiological and laboratory data may affect outcomes.
Models selected by stepwise selection methods tend to be suboptimal because important predictors may not be included, and regression coefficients and their SEs and P values may be biased toward more extreme values. We used backward selection with an α of 0.50 to reduce the number of covariates in the model. With the choice of a high α (0.50), the bias should be minimal.
Children with surgical cardiac disease have significantly better survival after in-hospital cardiac arrest compared with those in other categories of illness. Multiple variables may contribute to differences in outcomes. Intensive monitoring of at-risk populations that allows early detection of pulseless rhythms and the institution of aggressive support modalities may contribute to improved outcome in pediatric cardiac patients.
Dr Schexnayder is a compensated associate senior science editor for the American Heart Association Emergency Cardiac Care program. The other authors report no conflicts.
The American Heart Association GWTG-R Investigators include Mary E. Mancini, Robert A. Berg, Emilie Allen, Elizabeth A. Hunt, Vinay M. Nadkarni, Joseph P. Ornato, R. Scott Braithwaite, Graham Nichol, Kathy Duncan, Tanya L. Truitt, Brian Eigel, Peter C. Laussen, Frank W. Moler, Marilyn Morris, and Chris Parshuram.
- Received December 29, 2010.
- Accepted September 16, 2011.
- © 2011 American Heart Association, Inc.
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Survival after cardiac arrest is poor; however, small case series have suggested that children with cardiac disease who experience a cardiac arrest have better outcomes. Our study of 3323 pediatric patients using Get With the Guidelines–Resuscitation found that survival to hospital discharge was 37% in children with surgical cardiac disease compared with 28% in children with medical cardiac disease and 23% in children without cardiac disease. Although multiple previous studies have examined survival after cardiac arrest in the pediatric patients, children undergoing cardiac surgery are a unique population, and their survival after arrest has not been well studied. Children after cardiac surgery have a much higher risk of cardiac arrest compared with other pediatric populations, so this improved survival is encouraging for the providers who care for them. Notable is the higher odds of survival with the use of extracorporeal cardiopulmonary resuscitation, and this report adds to previous studies that have found extracorporeal cardiopulmonary resuscitation to be an effective rescue therapy. This study will be useful for medical providers when evaluating a patient's prognosis and provides information for researchers wanting to study this unique group of patients.