The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients

Association between post-cardiac arrest treatments and clinical outcomes according to scene time interval in out-of-hospital cardiac arrest: Retrospective cross-sectional study

BACKGROUND

Previous studies have reported that Post-Cardiac arrest (PCA) treatments including targeted temperature management (TTM), coronary reperfusion therapy (CRT), and extracorporeal membrane oxygenation (ECMO) are time-sensitive; however, there are no reports of the clinical outcomes of PCA treatment according to the scene time interval (STI). Our study aimed to investigated the clinical outcomes of PCA treatment according to the STI.

METHODS

We used a Korean nationwide OHCA cohort database from January 2017 to December 2020. The inclusion criteria were all adult OHCA patients with a presumed cardiac etiology, bystander-witnessed arrest, and prehospital return of spontaneous circulation (ROSC). The outcomes were survival to discharge and good neurological recovery. The main exposure of interest was PCA treatment. We compared the outcomes using multivariable logistic regression, and interaction terms were included in the final model to assess whether the STI modified the effect of PCA treatment on clinical outcomes of OHCA.

RESULTS

TTM and CRT were associated with high survival to discharge and good neurological recovery. In the interaction analysis, ECMO had an interaction effect with the STI on a good CPC among patients with OHCA [short STI (0 to 11 min) (1.16 (0.77-1.75)), middle STI (12 to 15 min) (0.66 (0.41-1.06)), and long STI (16 to 30 min) (0.59 (0.40-0.88)) (p for interaction <0.05)].

CONCLUSION

In adult bystander-witnessed patients with OHCA with prehospital ROSC, an STI of >16 min was a risk factor for poor neurological outcome in those patients who underwent ECMO.

At odds: How intraprofessional conflict and stratification has stalled the Ontario paramedic professionalization project

Historically, self-regulation has provided some professions with power and market control. Currently, however, governments have scrutinized this approach, and priorities have shifted toward other mandates. This study examines the case of paramedics in Ontario, Canada, where self-regulation is still the dominant regulatory model for the healthcare professions but not for paramedics. Instead, paramedics in Ontario are co-regulated by government and physician-directed groups, with paramedics subordinate to both. This paper, which draws on interviews with paramedic industry leaders analyzed through the lens of institutional work, examines perspectives on the relevance of self-regulation to the paramedic professionalization project. Participants had varying views on the importance of self-regulation in obtaining professional status, with some rejecting its role in professionalization and others embracing regulatory reform. Because paramedics disagree on what being a profession means, the collective professionalization project has stalled. This research has implications for understanding the impact of intraprofessional relationships and conflict on professionalization projects.

Disparities in Survival Outcomes of Out-of-Hospital Cardiac Arrest Patients between Urban and Rural Areas and the Identification of Modifiable Factors in an Area of South Korea

This retrospective study aimed to compare the survival outcomes of adult out-of-hospital cardiac arrest (OHCA) patients between urban (Busan, Ulsan, Changwon) and rural (Gyeongnam) areas in South Korea and identify modifiable factors in the chain of survival. The primary and secondary outcomes were survival to discharge and modifiable factors in the chain of survival were identified using logistic regression analysis. In total, 1954 patients were analyzed. The survival to discharge rates in the whole region and in urban and rural areas were 6.9%, 8.7% (Busan 8.7%, Ulsan 10.3%, Changwon 7.2%), and 3.4%, respectively. In the urban group, modifiable factors associated with survival to discharge were no advanced airway management (adjusted odds ratio (aOR) 2.065, 95% confidence interval (CI): 1.138–3.747), no mechanical chest compression (aOR 3.932, 95% CI: 2.015–7.674), and an emergency medical service (EMS) transport time of more than 8 min (aOR 3.521, 95% CI: 2.075–5.975). In the rural group, modifiable factors included an EMS scene time of more than 15 min (aOR 0.076, 95% CI: 0.006–0.883) and an EMS transport time of more than 8 min (aOR 4.741, 95% CI: 1.035–21.706). To improve survival outcomes, dedicated resources and attention to EMS practices and transport time in urban areas and EMS scene and transport times in rural areas are needed.

The State of Emergency Medical Services (EMS) Systems in Africa

Introduction

Little is known about the existence, distribution, and characteristics of Emergency Medical Services (EMS) systems in Africa, or the corresponding epidemiology of prehospital illness and injury.

Methods

A survey was conducted between 2013 and 2014 by distributing a detailed EMS system questionnaire to experts in paper and electronic versions. The questionnaire ascertained EMS systems’ jurisdiction, operations, finance, clinical care, resources, and regulatory environment. The discovery of respondents with requisite expertise occurred in multiple phases, including snowball sampling, a review of published scientific literature, and a rigorous search of the Internet.

Results

The survey response rate was 46%, and data represented 49 of 54 (91%) African countries. Twenty-five EMS systems were identified and distributed among 16 countries (30% of African countries). There was no evidence of EMS systems in 33 (61%) countries. A total of 98,574,731 (8.7%) of the African population were serviced by at least one EMS system in 2012. The leading causes of EMS transport were (in order of decreasing frequency): injury, obstetric, respiratory, cardiovascular, and gastrointestinal complaints. Nineteen percent of African countries had government-financed EMS systems and 26% had a toll-free public access telephone number. Basic emergency medical technicians (EMTs) and Basic Life Support (BLS)-equipped ambulances were the most common cadre of provider and ambulance level, respectively (84% each).

Conclusion

Emergency Medical Services systems exist in one-third of African countries. Injury and obstetric complaints are the leading African prehospital conditions. Only a minority (<9.0%) of Africans have coverage by an EMS system. Most systems were predominantly BLS, government operated, and fee-for-service.

Mould-MillmanNK, DixonJM, SefaN, YanceyA, HollongBG, HagahmedM, GindeAA, WallisLA. The state of Emergency Medical Services (EMS) systems in Africa. Prehosp Disaster Med. 2017;32(3):273–283.

Ethical Issues in Registry Research: In-Hospital Resuscitation as a Case Study

Research based on registry studies involves significant ethical issues. Using detailed information about one registry concerning in-hospital resuscitation, we present issues concerning informed consent, access to identifiable medical information, and benefit for participants. In addition, multiple methodological difficulties have indirect implications for the ethical conduct of registry research, including consensus about variable definitions, validity and reliability for clinical decisions, sample sizes, and sources of data. Both direct and indirect ethical issues are examined from the viewpoint of accepted regulations and codes regarding ethical conduct of research; specific examples of more or less ethical solutions to the problems are presented from published research.

The impact of prehospital resuscitation research on in-hospital care

Since their introduction over 40 years ago, paramedics have been trained to deliver select advanced life support interventions in the community with the goal of reducing morbidity and mortality from cardiovascular disease and trauma. The ensuing decades witnessed a great deal of interest in paramedic care, with an exponential growth in prehospital resuscitation research. As part of the CJEM series on emergency medical services (EMS), we review recent prehospital research in out-of-hospital cardiac arrest and discuss how, in a novel departure from the origins of EMS, prehospital research is beginning to influence in-hospital care. We discuss emerging areas of study related to cardiopulmonary resuscitation (CPR) quality, therapeutic hypothermia, termination of resuscitation, and the use of end-tidal carbon dioxide measurement, as well as the subtle ripple effects that prehospital research is having on the broader understanding of the management of these critically ill patients.

Prehospital vs. emergency department pronouncement of death: a cost analysis

Objective:

National survival rates for out-of-hospital cardiac arrests are less than 5%, and substantial resources are associated with transporting cardiac arrest victims to hospital for emergency department (ED) resuscitation. The low overall survival rate and the identification of predictors of unsuccessful resuscitation have opened debate on the “futility” of transporting such patients to the ED. This study compares the costs of prehospital pronouncement of death to the costs of transporting patients to a hospital ED for physician pronouncement.

Methods:

The study was a retrospective chart review on a matched cohort of out-of-hospital cardiac arrest patients. Patients were included if documentation was adequate and ambulance response time was less than 8 minutes. A cohort of 20 patients pronounced dead in the field were matched to 20 patients pronounced dead in an ED. Cases were matched on 6 evidence-based predictors of unsuccessful resuscitation. Direct medical costs and mean physician and prehospital provider times were compared.

Results:

The total cost of pronouncement of death in the ED was $45.35 higher than the cost of field pronouncement (p &lt; 0.001). Paramedics spent more time delivering care when death was pronounced in the field (83.3 vs. 55.9 min; p &lt; 0.001). Base hospital physicians spent more time when patients were transported to hospital for ED pronouncement (16.3 vs. 4.3 min; p &lt; 0.001). Total provider time for field pronouncement was 15.5 min longer (p = 0.004), but field pronouncement consumed 12.0 min less physician time.

Conclusions:

Paramedic pronouncement of death in the field is less costly than transporting patients to hospital for physician pronouncement. Pronouncement in the field requires more paramedic time but less physician time.

Factors affecting survival after prehospital asystolic cardiac arrest in a Basic Life Support-Defibrillation system

OBJECTIVES

Previous studies have shown a low but meaningful survival rate in cases of prehospital cardiac arrest with an initial rhythm of asystole. There may be, however, an identifiable subgroup in which resuscitation efforts are futile. This study identified potential field criteria for predicting 100% nonsurvival when the presenting rhythm is asystole in a Basic Life Support-Defibrillation (BLS-D) system.

METHODS

This prospective cohort study, a component of Phases I and II of the Ontario Prehospital Advanced Life Support (OPALS) Study, was conducted in 21 Ontario communities with BLS-D level of care, and included all adult arrests of presumed cardiac etiology according to the Utstein Style Guidelines. Analyses included descriptive and appropriate univariate tests, as well as multivariate stepwise logistic regression to determine predictors of survival.

RESULTS

From 1991 to 1997, 9899 consecutive cardiac arrest cases with the following characteristics: male (67.2%), bystander-witnessed (44.7%), bystander CPR (14.2%), call response interval (CRI) </= 8 minutes (82%) and overall survival (4.3%) were enrolled. Of 9529 cases with available rhythm strip recordings, initial arrest rhythms were asystole in 40.8%, pulseless electrical activity in 21.2% and ventricular fibrillation or ventricular tachycardia in 38%. Of 3888 asystolic patients, 9 (0.2%) survived to discharge; 3 of these cases were unwitnessed arrests with no bystander CPR. There were no survivors if the CRI exceeded 8 minutes. Logistic regression analysis demonstrated that independent predictors of survival to admission were "CRI in minutes" (odds ratio [OR] = 0.87; 95% confidence interval [CI], 0.77-0.98) and "bystander-witnessed" (OR = 2.6; 95% CI, 1.5-4.4).

CONCLUSIONS

In a BLS-D system, there is a very low but measurable survival rate for prehospital asystolic cardiac arrest. CRIs of over 8 minutes were associated with 100% nonsurvival, whereas unwitnessed arrests with no bystander CPR were not. These data add to the growing literature that will help guide ethical decision-making for protocol development in emergency medical services systems.

Risk adjustment measures and outcome measures for prehospital trauma research: recommendations from the emergency medical services outcomes project (EMSOP)

OBJECTIVES

The objectives were to conduct a comprehensive, systematic review of the literature for risk adjustment measures (RAMs) and outcome measures (OMs) for prehospital trauma research and to use a structured expert panel process to recommend measures for use in future emergency medical services (EMS) trauma outcomes research.

METHODS

A systematic literature search and review was performed identifying the published studies evaluating RAMs and OMs for prehospital injury research. An explicit structured review of all articles pertaining to each measure was conducted using the previously established methodology developed by the Canadian Physiotherapy Association ("Physical Rehabilitation Outcome Measures").

RESULTS

Among the 4,885 articles reviewed, 96 RAMs and/or OMs were identified from the existing literature (January 1958 to February 2010). Only one measure, the Glasgow Coma Scale (GCS), currently meets Level 1 quality of evidence status and a Category 1 (strong) recommendation for use in EMS trauma research. Twelve RAMs or OMs received Category 2 status (promising, but not sufficient current evidence to strongly recommend), including the motor component of GCS, simplified motor score (SMS), the simplified verbal score (SVS), the revised trauma score (RTS), the prehospital index (PHI), EMS provider judgment, the revised trauma index (RTI), the rapid acute physiology score (RAPS), the rapid emergency medicine score (REMS), the field trauma triage (FTT), the pediatric triage rule, and the out-of-hospital decision rule for pediatrics.

CONCLUSIONS

Using a previously published process, a structured literature review, and consensus expert panel opinion, only the GCS can currently be firmly recommended as a specific RAM or OM for prehospital trauma research (along with core measures that have already been established and published). This effort highlights the paucity of reliable, validated RAMs and OMs currently available for outcomes research in the prehospital setting and hopefully will encourage additional, methodologically sound evaluations of the promising, Category 2 RAMs and OMs, as well as the development of new measures.

Out-of-hospital cardiac arrest surveillance in Canada: a survey of national resources

OBJECTIVE

The general objective of this study was to explore the challenges of establishing an out of hospital cardiac arrest (OOHCA) surveillance program in Canada. More specifically, we attempted to determine the organizational structure of the delivery of emergency medical services (EMS) in Canada, describe the cardiac arrest data collection infrastructure in each province and determine which OOHCA variables are being collected.

METHODS

We conducted a national survey of 82 independent EMS health authorities in Canada. Methodology experts developed the survey and distribution using a modified Dillman technique. We distributed 67 surveys electronically (84%) and the rest by regular mail. We weighted each survey response by the population of the catchment area represented by the responding health authority (2004 census). Descriptive statistics are reported.

RESULTS

We received 60 completed surveys, representing a 73% response rate. The responding health authorities' catchment areas represented 80% of the Canadian population (territories excluded). Our survey results highlight a lack of common OOHCA data definitions used among health authorities, sporadic use of data quality assurance procedures, rare linkages to in hospital survival outcomes and potential confidentiality issues. Other challenges raised by respondents included determining warehousing location and finding financial resources for a national OOHCA registry.

CONCLUSION

Results from this survey demonstrate that, although it is challenging, it is possible to collect OOHCA data and access in hospital survival outcomes. Collaborative efforts with the Resuscitation Outcomes Consortium and other potential provincial partners should be explored.

Advanced airway management does not improve outcome of out-of-hospital cardiac arrest

BACKGROUND

The goal of out-of-hospital endotracheal intubation (ETI) is to reduce mortality and morbidity for patients with airway and ventilatory compromise. Yet several studies, mostly involving trauma patients, have demonstrated similar or worse neurologic outcomes and survival-to-hospital discharge rates after out-of-hospital ETI. To date, there is no study comparing out-of-hospital ETI to bag-valve-mask (BVM) ventilation for the outcome of survival to hospital discharge among nontraumatic adult out-of-hospital cardiac arrest (OOHCA) patients.

OBJECTIVES

The objective was to compare survival to hospital discharge among adult OOHCA patients receiving ETI to those managed with BVM.

METHODS

In this retrospective cohort study, the records of all OOHCA patients presenting to a municipal teaching hospital from November 1, 1994, through June 30, 2008, were reviewed. The type of field airway provided, age, sex, race, rhythm on paramedic arrival, presence of bystander cardiopulmonary resuscitation (CPR), whether the arrest was witnessed, site of arrest, return of spontaneous circulation (ROSC), survival to hospital admission, comorbid illnesses, and survival to hospital discharge were noted. A univariate odds ratio (OR) was first computed to describe the association between the type of airway and survival to hospital discharge. A multivariable logistic regression analysis was performed, adjusting for rhythm, bystander CPR, and whether the arrest was witnessed.

RESULTS

A cohort of 1,294 arrests was evaluated. A total of 1,027 (79.4%) received ETI, while 131 (10.1%) had BVM, 131 (10.1%) had either a Combitube or an esophageal obturator airway, and five (0.4%) had incomplete prehospital records. Fifty-five of 1,294 (4.3%) survived to hospital discharge; there were no survivors in the Combitube/esophageal obturator airway cohort. Even after multivariable adjustment for age, sex, site of arrest, bystander CPR, witnessed arrest, and rhythm on paramedic arrival, the OR for survival to hospital discharge for BVM versus ETI was 4.5 (95% confidence interval [CI] = 2.3-8.9; p<0.0001).

CONCLUSIONS

In this cohort, when compared to BVM ventilation, advanced airway methods were associated with decreased survival to hospital discharge among adult nontraumatic OOHCA patients.

Improved out-of-hospital cardiac arrest survival after the sequential implementation of 2005 AHA guidelines for compressions, ventilations, and induced hypothermia: the Wake County experience

STUDY OBJECTIVE

We assess survival from out-of-hospital cardiac arrest after community-wide implementation of 2005 American Heart Association guidelines.

METHODS

This was an observational multiphase before-after cohort in an urban/suburban community (population 840,000) with existing advanced life support. Included were all adults treated for cardiac arrest by emergency responders. Excluded were patients younger than 16 years and trauma patients. Intervention phases in months were baseline 16; phase 1, new cardiopulmonary resuscitation 12; phase 2, impedance threshold device 6; and phase 3, full implementation including out-of-hospital-induced hypothermia 12. Primary outcome was survival to discharge. Other survival and neurologic outcomes were compared between study phases, and adjusted odds ratios with 95% confidence intervals (CIs) for survival by phase were determined by multivariate regression.

RESULTS

One thousand three hundred sixty-five cardiac arrest patients were eligible for inclusion: baseline n=425, phase 1 n=369, phase 2 n=161, phase 3 n=410. Across phases, patients had similar demographic, clinical, and emergency medical services characteristics. Overall and witnessed ventricular fibrillation and ventricular tachycardia survival improved throughout the study phases: respectively, baseline 4.2% and 13.8%, phase 1 7.3% and 23.9%, phase 2 8.1% and 34.6%, and phase 3 11.5% and 40.8%. The absolute increase for overall survival from baseline to full implementation was 7.3% (95% CI 3.7% to 10.9%); witnessed ventricular fibrillation/ventricular tachycardia survival was 27.0% (95% CI 13.6% to 40.4%), representing an additional 25 lives saved annually in this community.

CONCLUSION

In the context of a community-wide focus on resuscitation, the sequential implementation of 2005 American Heart Association guidelines for compressions, ventilations, and induced hypothermia significantly improved survival after cardiac arrest. Further study is required to clarify the relative contribution of each intervention to improved survival outcomes.

Regional Systems of Care for Out-of-Hospital Cardiac Arrest

Out-of-hospital cardiac arrest continues to be an important public health problem, with large and important regional variations in outcomes. Survival rates vary widely among patients treated with out-of-hospital cardiac arrest by emergency medical services and among patients transported to the hospital after return of spontaneous circulation. Most regions lack a well-coordinated approach to post–cardiac arrest care. Effective hospital-based interventions for out-of-hospital cardiac arrest exist but are used infrequently. Barriers to implementation of these interventions include lack of knowledge, experience, personnel, resources, and infrastructure. A well-defined relationship between an increased volume of patients or procedures and better outcomes among individual providers and hospitals has been observed for several other clinical disorders. Regional systems of care have improved provider experience and patient outcomes for those with ST-elevation myocardial infarction and life-threatening traumatic injury. This statement describes the rationale for regional systems of care for patients resuscitated from cardiac arrest and the preliminary recommended elements of such systems. Many more people could potentially survive out-of-hospital cardiac arrest if regional systems of cardiac resuscitation were established. A national process is necessary to develop and implement evidence-based guidelines for such systems that must include standards for the categorization, verification, and designation of components of such systems. The time to do so is now.

What Are the Characteristics andOutcomes of Nontransported Pediatric Patients?

BACKGROUND

The authors have demonstrated that 28% of children cared for by paramedics are not transported to hospital by ambulance.

OBJECTIVE

To determine the characteristics, reasons, and outcomes for this nontransported population.

METHODS

This was a prospective cohort study in a single city with a two-tiered emergency medical services system. Enrolled were all children aged < 16 years assessed by paramedics but not transported to hospital over a five-month period. Data were collected from ambulance call reports, phone interviews, and hospital charts. Descriptive statistics were used.

RESULTS

Over five months, there were 345 nontransported pediatric patients with a mean age of 6 years, and 58.3% were male. The dispatch priority was urgent in 68.1% of cases and prompt in 30.4% of cases. The primary problems were almost evenly split between trauma (50.7%) and medical (45.2%) causes. Paramedics listed the following reasons for nontransport: parent will take the child to a physician (27.8%), parent will monitor the child's condition (25.8%), and no reason documented (46.4%). Phone interview was conducted with 106 parents (30.7%): 76.4% believed there was a true emergency at the time of the 9-1-1 call, 75.5% stated that the paramedics did not recommend that the child be transported to hospital by ambulance, and 29.2% stated that the paramedics said ambulance transport was not necessary. Fifty-one children were seen in an emergency department (ED) within 48 hours of the 9-1-1 call. The majority (91.3%) were discharged home from the ED, while a small minority (8.7%) were admitted to hospital. No deaths were reported.

CONCLUSIONS

Most nontransported children did not require immediate or urgent medical care. Both parents and paramedics gave input into the nontransport decision, and the short-term outcome of this population appeared to be good. Paramedic documentation for the reasons for nontransport should be improved.

Socioeconomic status influences bystander CPR and survival rates for out-of-hospital cardiac arrest victims

OBJECTIVES

While lower socioeconomic status is associated with lower level of education and increased incidence of cardiovascular diseases, the impact of socioeconomic status on out-of-hospital cardiac arrest outcomes is unclear. We used residential property values as a proxy for socioeconomic status to determine if there was an association with: (1) bystander CPR rates and (2) survival to hospital discharge for out-of-hospital cardiac arrest.

METHODS

We performed a secondary data analysis of cardiac arrest cases prospectively collected as part of the Ontario Prehospital Advanced Life Support study, conducted in 20 cities with ALS and BLS-D paramedics. We measured patient and system characteristics for cardiac arrests of cardiac origin, not witnessed by EMS, occurring in a single residential dwelling. We obtained property values from the Municipal Property Assessment Corporation. Analyses included descriptive statistics with 95% CIs and stepwise logistic regression.

RESULTS

Three thousand six hundred cardiac arrest cases met our inclusion criteria between 1 January 1995 and 31 December 1999. Patient characteristics were: mean age 69.2, male 67.8%, witnessed 44.7%, bystander CPR 13.2%, VF/VT 33.8%, time to vehicle stop 5:36min:s, return of spontaneous circulation 12.7%, and survival 2.7%. Median property value was $184,000 (range $25,500-2,494,000). For each $100,000 increment in property value, the likelihood of receiving bystander CPR increased (OR=1.07; 95% CI 1.01-1.14; p=0.03) and survival decreased (OR=0.77; 95% CI 0.61-0.97; p=0.03).

CONCLUSIONS

This is the largest study showing an association between socioeconomic status and survival, and the first study showing an association with bystander CPR. Our findings suggest targeting CPR training among lower socioeconomic groups.

Regional variation in out-of-hospital cardiac arrest incidence and outcome

CONTEXT

The health and policy implications of regional variation in incidence and outcome of out-of-hospital cardiac arrest remain to be determined.

OBJECTIVE

To evaluate whether cardiac arrest incidence and outcome differ across geographic regions.

DESIGN, SETTING, AND PATIENTS

Prospective observational study (the Resuscitation Outcomes Consortium) of all out-of-hospital cardiac arrests in 10 North American sites (8 US and 2 Canadian) from May 1, 2006, to April 30, 2007, followed up to hospital discharge, and including data available as of June 28, 2008. Cases (aged 0-108 years) were assessed by organized emergency medical services (EMS) personnel, did not have traumatic injury, and received attempts at external defibrillation or chest compressions or resuscitation was not attempted. Census data were used to determine rates adjusted for age and sex.

MAIN OUTCOME MEASURES

Incidence rate, mortality rate, case-fatality rate, and survival to discharge for patients assessed or treated by EMS personnel or with an initial rhythm of ventricular fibrillation.

RESULTS

Among the 10 sites, the total catchment population was 21.4 million, and there were 20,520 cardiac arrests. A total of 11,898 (58.0%) had resuscitation attempted; 2729 (22.9% of treated) had initial rhythm of ventricular fibrillation or ventricular tachycardia or rhythms that were shockable by an automated external defibrillator; and 954 (4.6% of total) were discharged alive. The median incidence of EMS-treated cardiac arrest across sites was 52.1 (interquartile range [IQR], 48.0-70.1) per 100,000 population; survival ranged from 3.0% to 16.3%, with a median of 8.4% (IQR, 5.4%-10.4%). Median ventricular fibrillation incidence was 12.6 (IQR, 10.6-5.2) per 100,000 population; survival ranged from 7.7% to 39.9%, with a median of 22.0% (IQR, 15.0%-24.4%), with significant differences across sites for incidence and survival (P<.001).

CONCLUSION

In this study involving 10 geographic regions in North America, there were significant and important regional differences in out-of-hospital cardiac arrest incidence and outcome.

Resuscitation Outcomes Consortium (ROC) PRIMED cardiac arrest trial methods part 2: rationale and methodology for "Analyze Later vs. Analyze Early" protocol

OBJECTIVE

The primary objective of the trial is to compare survival to hospital discharge with modified Rankin score (MRS) < or =3 between a strategy that prioritizes a specified period of CPR before rhythm analysis (Analyze Later) versus a strategy of minimal CPR followed by early rhythm analysis (Analyze Early) in patients with out-of-hospital cardiac arrest.

METHODS

Design-Cluster randomized trial with cluster units defined by geographic region, or monitor/defibrillator machine. Population-Adults treated by emergency medical service (EMS) providers for non-traumatic out-of-hospital cardiac arrest not witnessed by EMS. Setting-EMS systems participating in the Resuscitation Outcomes Consortium and agreeing to cluster randomization to the Analyze Later versus Analyze Early intervention in a crossover fashion. Sample size-Based on a two-sided significance level of 0.05, a maximum of 13,239 evaluable patients will allow statistical power of 0.996 to detect a hypothesized improvement in the probability of survival to discharge with MRS < or =3 rate from 5.41% after Analyze Early to 7.45% after Analyze Later (2.04% absolute increase in primary outcome).

CONCLUSION

If this trial demonstrates a significant improvement in survival with a strategy of Analyze Later, it is estimated that 4000 premature deaths from cardiac arrest would be averted annually in North America alone.

Comparison of the Cerebral Performance Category score and the Health Utilities Index for survivors of cardiac arrest

STUDY OBJECTIVE

The Cerebral Performance Category score is an easy to use but unvalidated measure of functional outcome after cardiac arrest. We evaluate the comparability of results from the Cerebral Performance Category scale versus those of the validated but more complex Health Utilities Index scale for health-related quality of life.

METHODS

This prospective substudy of the Ontario Prehospital Advanced Life Support (OPALS) Study included adult out-of-hospital cardiac arrest patients treated in 20 cities. This prospective cohort study included all survivors of out-of-hospital adult cardiac arrest enrolled in phase II (rapid basic life support with defibrillation) and phase III (advanced life support) of the OPALS Study, as well as the intervening run-in phase. Survivors were interviewed at 12 months for Cerebral Performance Category Score and the Health Utilities Index Mark 3 (Health Utilities Index).

RESULTS

Of 8,196 eligible out-of-hospital cardiac arrest patients between 1995 and 2002, 418 (5.1%) survived to discharge, and 305 (3.7%) completed the Health Utilities Index interview and had Cerebral Performance Category scored at 12 months. The 305 patients had the following data: mean age 63.9 years; male 78.0%; paramedic-witnessed arrest 25.6%; bystander cardiopulmonary resuscitation 32.1%; initial rhythm ventricular fibrillation/ventricular tachycardia 86.9%, Cerebral Performance Category 1 267, Cerebral Performance Category 2 26, Cerebral Performance Category 3 12. Overall, the median scores (interquartile range) were Cerebral Performance Category 1 (1 to 1) and Health Utilities Index 0.84 (0.61 to 0.97). The Cerebral Performance Category score ruled out good quality of life (Health Utilities Index >0.80), with a sensitivity of 100% (95% confidence interval [CI] 98% to 100%) and specificity 27.1% (95% CI 20% to 35%); thus, when the Cerebral Performance Category score was 2 or 3, it was unlikely that the Health Utilities Index score would be good. The Cerebral Performance Category score had sensitivity 55.6% (95% CI 42% to 67%) and specificity 96.8% (95% CI 94% to 98%) for predicting poor quality of life (Health Utilities Index >0.40); ie, when Cerebral Performance Category was 1, it was highly unlikely that the Health Utilities Index score would be poor. The weighted kappa was 0.39 and the interclass correlation was 0.51.

CONCLUSION

This represents the largest study yet conducted of the performance of the Cerebral Performance Category score in 1-year survivors of out-of-hospital cardiac arrest. Overall, the Cerebral Performance Category score classified patients well for their quality of life, ruling out a good Health Utilities Index score with high sensitivity and ruling in poor Health Utilities Index score with high specificity. The Cerebral Performance Category is an important tool in that it indicates broad functional outcome categories that are useful for a number of key clinical and research applications but should not be considered a substitute for the Health Utilities Index.

Evaluating the effectiveness of dispatch-assisted cardiopulmonary resuscitation instructions

OBJECTIVES

To determine the frequency of agonal breathing during cardiac arrest (CA), its impact on the ability of 9-1-1 dispatchers to identify CA, and the impact of dispatch-assisted cardiopulmonary resuscitation (CPR) instructions on bystander CPR rates.

METHODS

A before-after observational study enrolling out-of-hospital adult CA patients where resuscitation was attempted in a single city with basic life support with defibrillation/advanced life support tiered emergency medical services. Victim, caller, and system characteristics were measured during two successive nine-month periods before (control group) and after (intervention group) the introduction of dispatch-assisted CPR instructions.

RESULTS

There were 529 CAs between July 1, 2003, and December 31, 2004. Victim characteristics were similar in the control (n = 295) and intervention (n = 234) period; mean age was 68.3 years; 66.7% were male; 50.1% of CAs were witnessed; call-to-vehicle stop was 6 minutes, 37 seconds; ventricular fibrillation/ventricular tachycardia occurred in 29.9%; and the survival rate was 4.0%. Dispatchers identified 56.3% (95% confidence interval [CI] = 48.9% to 63.0%) of CA cases; agonal breathing was present in 37.0% (95% CI = 30.1% to 43.9%) of all CA cases and accounted for 50.0% (95% CI = 39.1% to 60.9%) of missed diagnoses. Callers provided ventilations in 17.2% and chest compressions in 8.3% of cases as a result of the intervention. Long time intervals were observed between call to diagnosis (2 minutes, 38 seconds) and during ventilation instructions (2 minutes, 5 seconds). Bystander CPR rates increased from 16.7% in the control phase to 26.4% in the intervention phase (absolute rate, 9.7%; 95% CI = 8.5% to 11.3%; p = 0.006).

CONCLUSIONS

This trial demonstrates an increase in bystander CPR rate after the introduction of dispatch-assisted CPR. Agonal breathing occurred frequently and had a negative impact on the recognition of CA. There were long time intervals between call initiation and diagnosis of CA and during mouth-to-mouth ventilation instructions.

Derivation and evaluation of a termination of resuscitation clinical prediction rule for advanced life support providers

OBJECTIVES

The primary aim was to derive a new termination of resuscitation (TOR) clinical prediction rule for advanced life support paramedics (ALS) and to measure both its pronouncement rate and diagnostic test characteristics. Secondary aims included measuring the test characteristics of a previously derived and published basic life support termination of resuscitation (BLS TOR) clinical prediction rule [Morrison LJ, Visentin LM, Kiss A, et al. Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med 2006;355(5):478-87] on the same cohort of patients for comparison purposes.

METHODS

Secondary data analysis of adult cardiac arrests treated by ALS in rural and urban EMS systems participating in the OPALS study (data extracted from Phase III). A previous study for a basic life support termination of resuscitation (BLS TOR) clinical prediction rule proposed Termination of Resuscitation if the patient had no return of spontaneous circulation (ROSC) before transport; no shock administered; EMS personnel did not witness the arrest [Morrison LJ, Visentin LM, Kiss A, et al. Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med 2006;355(5):478-87]. Multivariable logistic regression was used to examine the relationship between these variables, additional Utstein variables, and the primary outcome of survival to hospital discharge. Diagnostic test characteristics were measured for both the ALS TOR and BLS TOR models on this derivation cohort.

RESULTS

Four thousand six hundred and seventy-three cardiac arrest patients were included; 3098 (66%) were male, mean (S.D.) age 69 (15); 239 (5.1%; 95% CI 4.5-5.8) survived to hospital discharge; 3841 patients had no ROSC (82%) and of these only three survived (0.08%; 95% CI 0.02, 0.23). The final ALS TOR model associated with survival, included: ROSC (OR 260.9; 95% CI 96.3, 706.7), bystander witnessed (OR 2.0; 95% CI 1.3, 3.1), bystander CPR (OR 2.8; 95% CI 1.9, 4.1), EMS witnessed (OR 12.3; 95% CI 7.1, 21.3) and shock prior to transport (OR 6.4; 95% CI 4.1, 10.1). A new ALS TOR clinical prediction rule based on these variables was 100% sensitive (95% CI 99.9-100) for survival and had 100% negative predictive value (95% CI 99.9-100) for death. Under the ALS TOR clinical prediction rule, 30% of patients would be pronounced in the field. The BLS TOR clinical prediction rule, was 100% sensitive (95% CI 99.9, 100), had 100% negative predictive value (95% CI 99.9-100) and the field pronouncement rate was 48%.

CONCLUSION

Cardiac arrest patients may be considered for prehospital ALS TOR when there is no ROSC prior to transport, no shock delivered, no bystander CPR and the arrest was not witnessed by bystanders or EMS. A single EMS termination clinical prediction rule for all levels of providers would be optimal for EMS systems to implement. Prospective evaluation of the ALS TOR clinical prediction rule in the hands of ALS providers will be required before implementation.

Assessing automated external defibrillators in preventing deaths from sudden cardiac arrest: An economic evaluation

Objectives:The aim of this study was to evaluate the cost-effectiveness of on-site automated external defibrillators (AEDs) in the initial management of cardiac arrest in Ontario.

Methods:This was a cost-effectiveness analysis based on published literature and data from the Canadian Institute of Health Information. The participants were fictitious male and female cardiac arrest patients who were initially managed with on-site AEDs, compared with similar patients managed without on-site AEDs. This group included a subgroup of high-risk patients (i.e., heart failure and left ventricular ejection fraction <35 percent). The analysis was conducted in a variety of settings including hospitals and homes in Ontario, Canada. The main outcome evaluated was cost per quality-adjusted life-year (QALY) gained from a payer's perspective.

Results:Cost per QALY (all costs reported in Canadian dollars) was $12,768 when AEDs were deployed in hospitals, $511,766 when deployed in office buildings, $2,360,023 when deployed in apartment buildings, $87,569 when deployed in homes of high-risk patients, and $1,529,371 when deployed in homes of people older than 55 years of age.

Conclusions:Indiscriminate deployment of AEDs is not a cost-effective means of improving health outcomes of cardiac arrest. Their use should be restricted to emergency response programs, high-risk sites (such as hospitals), and high-risk patients.

Advanced life support for out-of-hospital respiratory distress

BACKGROUND

Respiratory distress is a common symptom of patients transported to hospitals by emergency medical services (EMS) personnel. The benefit of advanced life support for such patients has not been established.

METHODS

The Ontario Prehospital Advanced Life Support (OPALS) Study was a controlled clinical trial that was conducted in 15 cities before and after the implementation of a program to provide advanced life support for patients with out-of-hospital respiratory distress. Paramedics were trained in standard advanced life support, including endotracheal intubation and the administration of intravenous drugs.

RESULTS

The clinical characteristics of the 8138 patients in the two phases of the study were similar. During the first phase, no patients were treated by paramedics trained in advanced life support; during the second phase, 56.6% of patients received this treatment. Endotracheal intubation was performed in 1.4% of the patients, and intravenous drugs were administered to 15.0% during the second phase. This phase of the study was also marked by a substantial increase in the use of nebulized salbutamol and sublingual nitroglycerin for the relief of symptoms. The rate of death among all patients decreased significantly, from 14.3% to 12.4% (absolute difference, 1.9%; 95% confidence interval [CI], 0.4 to 3.4; P=0.01) from the basic-life-support phase to the advanced-life-support phase (adjusted odds ratio, 1.3; 95% CI, 1.1 to 1.5).

CONCLUSIONS

The addition of a specific regimen of out-of-hospital advanced-life-support interventions to an existing EMS system that provides basic life support was associated with a decrease in the rate of death of 1.9 percentage points among patients with respiratory distress.

Design and implementation of resuscitation research: special challenges and potential solutions

Evaluation of the effectiveness of resuscitation interventions is challenging. We describe these challenges, which include design, enrolment and analysis issues. Randomized trials establish if interventions work in predefined populations. "Efficacy" trials determine whether interventions work under ideal conditions. "Effectiveness" trials determine whether interventions work under usual practice conditions. These trials represent a trade-off between internal validity versus external validity. Randomized trials use random allocation of participants to interventions to produce study groups that are similar with respect to known and unknown risk factors, reduce bias in the allocation of participants, and assure that statistical tests have valid significance levels. In the emergency setting, there is a risk that treatment offered to control patients will be contaminated by providers' experiences of applying the intervention to patients receiving the experimental intervention. Frequently there is not time to obtain consent from a patient in an emergency setting. Exception from consent can be applied if certain conditions are met. Enrolment in a research study must be initiated quickly in an emergency setting or the patient will die or become disabled. In any trial, data can be used to explore different aspects of response to treatment: multiple treatments, subgroups, events; and interim analyses. We propose solutions to these challenges to help potential investigators through the myriad of difficulties in initiating trials in a complex environment. Design of simple trials that have adequate power enhances their external validity. Allocating groups of episodes to interventions by randomizing by clusters, rather than by individual patients reduces provider noncompliance. Waiver from consent for emergency research and use of novel technologies could facilitate enrolment despite time constraints. Rigorous statistical methods can be used to analyze multiple data without an excessive increase in the chance of a false-positive result.

Management and outcomes of pediatric patients transported by emergency medical services in a Canadian prehospital system

OBJECTIVES

There is uncertainty around the types of interventions that are provided by emergency medical services (EMS) to children during prehospital transport. We describe the patient characteristics, events, interventions provided and outcomes of a cohort of children transported by EMS.

METHODS

This prospective cohort study was conducted in a city of 750 000 people with a 2-tiered EMS system. All children <16 years of age who were attended by EMS during a 6-month period were enrolled. Data were extracted from ambulance call reports and hospital charts, and analyzed using descriptive statistics.

RESULTS

During the study period there were 1377 pediatric EMS calls. Mean age was 8.2 years (standard deviation 5.4), and the most Common diagnoses were trauma (44.9%), seizure (11.8%) and respiratory distress (8.8%). The ambulance return code was Urgent in 7%, Prompt in 57%, Deferrable in 8% and Not Transported in 28%. Fifty-six percent received either an Advanced Life Support or Basic Life Support prehospital intervention. Common procedures included cardiac monitoring (20.0%), oxygen administration (19.8%), blood glucose monitoring (16.3%), spine board (12.2%), limb immobilization (11.1%) and cervical collar (10.0%). Uncommon procedures included administering medications intravenously (IV) (1.4%), bag-valve-mask ventilation (0.3%) and endotracheal intubation (0.1%). Seventy-eight percent of attempted IV lines were successful. Only 9.0% of EMS-transported children were admitted to hospital, and 2.2% were admitted to the intensive care unit.

CONCLUSIONS

This first study of Canadian pediatric prehospital interventions shows a high rate of non-transport, and a low rate of Urgent transports and hospital admissions for children. Very few children receive prehospital airway management, ventilation or IV medications; consequently EMS personnel have little opportunity to maintain these pediatric skills in the field.

Comparing pre-hospital clinical diagnosis of pediatric out-of-hospital cardiac arrest with etiology by coroner's diagnosis

OBJECTIVES

Making an accurate clinical diagnosis in the field can be a great challenge with pediatric out-of-hospital cardiac arrest (OHCA). We aimed to compare the etiology of pediatric OHCA by pre-hospital clinical diagnosis with etiology by coroner's diagnosis and autopsy.

DESIGN

As part of the Ontario Pre-hospital Advanced Life Support (OPALS) study, we conducted a prospective cohort study including children below age 19 with OHCA during an 11-year period. Prehospital clinical diagnosis was determined by blinded review and deaths were then matched with provincial coroner's office records. The agreement between prehospital clinical diagnosis and autopsy diagnosis was derived by consensus review. Inter-observer agreement was evaluated using kappa values.

RESULTS

For the period 1992-2002, there were 414 cardiac arrests in children <19 years of age that matched coroner's records. Mean age was 5.9 years (S.D. 6.4 years) with 39.4% of cases under 1 year of age. Etiology by clinical diagnosis was medical 49.5%, trauma 36.0% and undetermined 14.5%. The overall kappa for clinical diagnosis compared to coroner's diagnosis was 0.62. The kappa for medical cases was 0.53, trauma was 0.93 and 'undetermined' was -0.01. Medical clinical diagnosis had a lower agreement with the coroner's diagnosis (62.4%) compared with trauma (96.0%), RR 0.65, 95% CI [0.58, 0.73]. The poorest kappas by diagnosis were for neurological (0.39), respiratory (0.42), 'other' medical (0.56), SIDS (0.58) and cardiac (0.63). The commonest coroner's diagnoses in the 'undetermined' clinical diagnosis category were: pneumonia (17.6%), seizure or post-seizure (11.8%), arrhythmia (9.8%) and aspiration (5.9%).

CONCLUSION

Even in an ideal situation, a clinician in the field might be unable to determine the etiology of pediatric cardiac arrest in 14.5% of cases. There is poorer agreement for 'medical' compared to 'trauma' cases. This is the largest study to date comparing clinical diagnosis of the causes of OHCA in children to the 'gold-standard' of coroner's diagnosis.

What are the etiology and epidemiology of out-of-hospital pediatric cardiopulmonary arrest in Ontario, Canada?

BACKGROUND

Pediatric cardiopulmonary arrest (CPA) outside of the hospital has a very high mortality rate.

OBJECTIVES

To evaluate the etiology and initial compromise of pediatric CPA cases in hopes of developing strategies to improve out-of-hospital resuscitation.

METHODS

The Ontario Prehospital Advanced Life Support (OPALS) study was a large multicenter initiative to evaluate the impact of emergency medical services (EMS) programs on 17 communities with 40,000 critically ill and injured patients who were older than 11 years. As part of this study, the authors conducted a retrospective observational cohort study that included all children younger than 18 years of age with out-of-hospital CPA, during an 11-year period from 1991-2002. CPA was defined as patient being pulseless, apneic, and requiring chest compressions. Data were collected from ambulance call reports and centralized dispatch data and were reviewed by two independent investigators.

RESULTS

There were 503 children with CPA in the sample. Mean age was 5.6 years (range, 0-17 yr); 58.4% of patients were male, and 37.8% were younger than 1 year of age. Cardiopulmonary resuscitation (CPR) first was started by a bystander in 32.4% of cases, whereas 66.0% were unwitnessed arrests. Initial rhythms were asystole 77.2% of the time, pulseless electrical activity 16.4% of the time, and ventricular fibrillation or ventricular tachycardia 4% of the time. Annual incidence was 9.1/100,000 children. CPA was witnessed in 34.0% of cases; 80.7% of these were bystander-witnessed, and 18.1% were EMS-witnessed. Primary pathogenic cause of arrest was medical in 61.2% of cases, trauma in 37.2% of cases, and indeterminate in 1.6% of cases. Initial underlying physiologic compromise of witnessed arrests was judged to be respiratory in 39.8% of cases, sudden collapse (presumed electrical) in 16.4% of cases, progressive shock in 1.2% of cases, and indeterminate in 42.6% of cases. Presumed etiology was trauma, 37.6%; sudden infant death syndrome (SIDS), 20.3%; and respiratory disease, 11.6%, most commonly. Survival to hospital discharge was 2.0%.

CONCLUSIONS

This is one of the largest population-based, prospective cohorts of pediatric CPA reported to date, and it reveals that most pediatric arrests are unwitnessed and receive no bystander CPR. Those that are witnessed most often are caused by respiratory arrests or trauma. Trauma, SIDS, and respiratory disease are the most common etiologies overall. These data are vital to planning large resuscitation trials looking at specific interventions (i.e., increasing bystander CPR) and highlight the need for better strategies for prevention and early recognition.

Comparison of Termination-of-Resuscitation Guidelines for Basic Life Support: Defibrillator Providers in Out-of-Hospital Cardiac Arrest

STUDY OBJECTIVE

Termination of resuscitation in the field for out-of-hospital cardiac arrest can reduce unnecessary transport to hospital and associated road hazards and increase availability of emergency medical services (EMS) and emergency department resources for other patients. We compare the performance of 3 termination-of-resuscitation guidelines for basic life support-defibrillator (BLS) providers when applied to cardiac arrest patients in the Ontario Prehospital Advanced Life Support study.

METHODS

This prospective cohort study involved all out-of-hospital cardiac arrest patients attended by BLS defibrillator providers in 21 Ontario urban or suburban communities. The data analyses were conducted secondarily on these prospectively collected data. Three termination-of-resuscitation guidelines (referred to as Marsden, Petrie, and Verbeek rules) were applied and contingency tables calculated to show the relationship between the rule and actual survival.

RESULTS

From 1988 to 2003, 13,684 cardiac arrest patients were attended by BLS defibrillator providers. Six hundred thirty-six (4.7%) patients survived to hospital discharge. For the 3 termination-of-resuscitation rules, sensitivity was 99.8% (95% confidence interval [CI] 99.5% to 100.0%) (Petrie rules), 99.5% (95% CI 99.0% to 100.0%) (Verbeek rules), and 99.8% (95% CI 99.5% to 100.0%) (Marsden rules). Specificity was 9.9% (95% CI 9.4% to 10.4%) (Petrie rules), 52.9% (95% CI 52.1% to 53.8%) (Verbeek rules), and 19.4 % (95% CI 18.8% to 20.1%) (Marsden rules). Negative predictive value was 99.9% (95% CI 99.8% to 100.0%) (Petrie rules), 100.0% (95% CI 99.9% to 100.0%) (Verbeek rules), and 100.0% (95% CI 99.9% to 100.0%) (Marsden rules). These rules would have resulted in field termination of resuscitation in 9.4% (Petrie rules), 50.5% (Verbeek rules), and 18.5 % (Marsden rules) of cases. Termination of resuscitation was recommended for 1 patient (Petrie rules), 3 patients (Verbeek rules), and 1 patient (Marsden rules), who survived.

CONCLUSION

We found all 3 termination-of-resuscitation rules to have high sensitivity and negative predictive value. However, the specificity and transport rates varied greatly. The results of this study will be useful for EMS providers considering adoption of termination of resuscitation in BLS defibrillator systems for out-of-hospital cardiac arrest.

Economic value of out-of-hospital emergency care: a structured literature review

STUDY OBJECTIVE

The evaluation of the impact of out-of-hospital emergency care is a relatively new research focus. As such, there is a compelling need to determine how finite health care resources should be used in this setting. The objective of this study is to conduct a structured review of published economic evaluations of out-of-hospital emergency care to assess its economic value.

METHODS

A structured literature search and structured review of articles pertaining to the economic value of out-of-hospital care was performed. The bibliographic database MEDLINE was searched for pertinent English-language articles published between 1966 and 2003. The search used the medical subject headings "emergency medical services" and "emergency medical technician" and was limited to the subheading "economics" and crossed with the medical subject heading "economics." The titles generated by this search were systematically reviewed and limited by topic. Abstracts from the identified titles were reviewed to select a final set of pertinent articles. These articles were further limited based on explicit inclusion and exclusion criteria. Authors used a previously published structured evaluation tool to review the final set of identified articles for quality and content.

RESULTS

The initial MEDLINE search identified 3,533 citations. From this set, 535 potentially relevant abstracts were reviewed. From the abstract review, 46 articles were identified, along with an additional 14 from searching the secondary references. Of these 60 articles, 32 met the review inclusion criteria and were subjected to a full structured review. These studies predominantly addressed the cost of cardiac arrest (n=13, 41%), major trauma (n=8, 25%), and emergency medical services treatment in general (n=8, 25%). Only 14 studies considered the costs and consequences of competing alternatives. Of these, 2 were cost-benefit and 12 were cost-effectiveness evaluations. Two of the 14 studies met all 10 criteria for high-quality economic evaluation, whereas 2 others met none.

CONCLUSION

There is a paucity of out-of-hospital care literature that addresses cost and economic value. The extant literature is limited in scope, poor in quality, and evaluates small subsets of out-of-hospital emergency care costs. Favorable cost-effectiveness has not been firmly established for most aspects of out-of-hospital emergency care.

Etiology of pediatric out-of-hospital cardiac arrest by coroner's diagnosis

OBJECTIVES

To determine etiology of pediatric OHCA in a population-based sample from autopsy and coroner's diagnosis.

DESIGN

As part of the Ontario Pre-hospital Advanced Life Support (OPALS) study, we conducted a prospective cohort study including children below age 19 years with OHCA in an 11-year period. Deaths were matched with provincial coroner's office records and autopsies and investigation notes were reviewed.

RESULTS

From 1992 to 2002, there were 474 cardiac arrests in children below 19 years of age giving an annual incidence of 59.7 per million children. Mean age was 5.8 (S.D. 6.3), 43.0% were <1 year of age, males were 59.1%. 25.1% were bystander witnessed and 20.3% received bystander CPR. 1.9% survived to discharge. Four hundred and thirty nine matched to coroner's office records. Annual incidence rates per million by age groups were: 175.0 (age 1-4 years), 33.0 (age 5-14 years) and 61.6 (age 15-18). Annual incidence rates per million according to coroner's cause of death were: natural (26.2), accidental (17.4), suicide (3.7) and homicide (1.9). Post-mortem rate was 84.3% and Mean Injury Severity Score was 31.4 (S.D. 16.5). The commonest causes of natural death were SIDS (30.3%), cardiovascular (19.2) and respiratory (18.3%). The commonest causes of accidental death were drowning (27.5%), residential accidents (18.8%), fire (13.0%) and motor vehicle collisions (12.3%).

CONCLUSION

The highest mortality rates were among children age <4 years. 52.6% of deaths were from 'unnatural' causes (accidental, suicide, homicide, undetermined). Our findings will be useful for planning prevention, treatment and future research of pediatric OHCA.

Methodological design for economic evaluation in Public Access Defibrillation (PAD) trial

OBJECTIVE

Our objective is to describe the rationale and methods for the economic analysis of the PAD trial. The objective of this analysis is to assess whether automated external defibrillators (AEDs) use by lay responders is good value for money.

METHODS

Design. This economic evaluation is being conducted concurrently with a randomized trial of (a) control--training to recognize arrest, access 911, and administer cardiopulmonary resuscitation (CPR) while awaiting arrival of emergency medical services providers versus (b) intervention--training to recognize arrest, access 911, administer CPR, and use an AED while awaiting emergency medical services providers. Lay responders in either group were trained to deliver the study intervention. Population. Participating sites identified distinct units with a population of at least 250 people aged > or = 50 years. Outcome. The primary economic outcome is the incremental cost-effectiveness ratio of intervention versus control.

RESULTS

Nine hundred ninety-three units including 1260 public and residential locations were randomized. There were 30 survivors in the intervention group and 15 in the control group (P = .03). Sampling will identify program and health care costs. A societal perspective will be adopted. Incremental cost effectiveness will be estimated by using bootstrapping and decision analytic modeling.

CONCLUSION

The study will demonstrate whether defibrillation by lay responders improves outcomes at reasonable cost. If so, then the thousands of lives will be improved annually. If not, then limited resources can be invested in other interventions. Our methods also provide a framework for economic evaluations of other interventions for acute cardiovascular events.

Use of implantable cardioverter defibrillators after out-of-hospital cardiac arrest: a prospective follow-up study

BACKGROUND

Survivors of out-of-hospital cardiac arrest are at high risk of recurrent arrests, many of which could be prevented with implantable cardioverter defibrillators (ICDs). We sought to determine the ICD insertion rate among survivors of out-of-hospital cardiac arrest and to determine factors associated with ICD implantation.

METHODS

The Ontario Prehospital Advanced Life Support (OPALS) study is a prospective, multiphase, before-after study assessing the effectiveness of prehospital interventions for people experiencing cardiac arrest, trauma or respiratory arrest in 19 Ontario communities. We linked OPALS data describing survivors of cardiac arrest with data from all defibrillator implantation centres in Ontario.

RESULTS

From January 1997 to April 2002, 454 patients in the OPALS study survived to hospital discharge after experiencing an out-of-hospital cardiac arrest. The mean age was 65 (standard deviation 14) years, 122 (26.9%) were women, 398 (87.7%) had a witnessed arrest, 372 (81.9%) had an initial rhythm of ventricular tachycardia or ventricular fibrillation (VT/VF), and 76 (16.7%) had asystole or another arrhythmia. The median cerebral performance category at discharge (range 1-5, 1 = normal) was 1. Only 58 (12.8%) of the 454 patients received an ICD. Patients with an initial rhythm of VT/VF were more likely than those with an initial rhythm of asystole or another rhythm to undergo device insertion (adjusted odds ratio [OR] 9.63, 95% confidence interval [CI] 1.31-71.50). Similarly, patients with a normal cerebral performance score were more likely than those with abnormal scores to undergo ICD insertion (adjusted OR 12.52, 95% CI 1.74-92.12).

INTERPRETATION

A minority of patients who survived cardiac arrest underwent ICD insertion. It is unclear whether this low usage rate reflects referral bias, selection bias by electrophysiologists, supply constraint or patient preference.

Advanced cardiac life support in out-of-hospital cardiac arrest

BACKGROUND

The Ontario Prehospital Advanced Life Support (OPALS) Study tested the incremental effect on the rate of survival after out-of-hospital cardiac arrest of adding a program of advanced life support to a program of rapid defibrillation.

METHODS

This multicenter, controlled clinical trial was conducted in 17 cities before and after advanced-life-support programs were instituted and enrolled 5638 patients who had had cardiac arrest outside the hospital. Of those patients, 1391 were enrolled during the rapid-defibrillation phase and 4247 during the subsequent advanced-life-support phase. Paramedics were trained in standard advanced life support, which includes endotracheal intubation and the administration of intravenous drugs.

RESULTS

From the rapid-defibrillation phase to the advanced-life-support phase, the rate of admission to a hospital increased significantly (10.9 percent vs. 14.6 percent, P<0.001), but the rate of survival to hospital discharge did not (5.0 percent vs. 5.1 percent, P=0.83). The multivariate odds ratio for survival after advanced life support was 1.1 (95 percent confidence interval, 0.8 to 1.5); after an arrest witnessed by a bystander, 4.4 (95 percent confidence interval, 3.1 to 6.4); after cardiopulmonary resuscitation administered by a bystander, 3.7 (95 percent confidence interval, 2.5 to 5.4); and after rapid defibrillation, 3.4 (95 percent confidence interval, 1.4 to 8.4). There was no improvement in the rate of survival with the use of advanced life support in any subgroup.

CONCLUSIONS

The addition of advanced-life-support interventions did not improve the rate of survival after out-of-hospital cardiac arrest in a previously optimized emergency-medical-services system of rapid defibrillation. In order to save lives, health care planners should make cardiopulmonary resuscitation by citizens and rapid-defibrillation responses a priority for the resources of emergency-medical-services systems.

Health-Related Quality of Life Is Better for Cardiac Arrest Survivors Who Received Citizen Cardiopulmonary Resuscitation

Background— This study evaluated the prehospital factors associated with better health-related quality of life for survivors of out-of-hospital cardiac arrest.

Methods and Results— This prospective, 20-community, cohort study involved consecutive, adult out-of-hospital cardiac arrest patients who survived to 1 year. Patients were contacted by telephone and evaluated for the Health Utilities Index Mark III (HUI3), which describes health as a utility score on a scale from 0 (dead) to 1.0 (perfect health). The 8091 cardiac arrest patients had overall survival rates of 5.2% to hospital discharge and 4.0% to 1 year. We successfully contacted and evaluated 268 of 316 (84.8%) of known 1-year survivors. The median HUI3 score was 0.80 (interquartile range, 0.50 to 0.97), which compares well with age-adjusted values for the general population (0.83). Logistic regression identified 2 factors independently associated with very good quality of life (HUI3 >0.90) and their odds ratios (95% CIs), as follows: age 80 years or older, 0.3 (0.1 to 0.84), and citizen-initiated cardiopulmonary resuscitation (CPR), 2.0 (1.2 to 3.4) (Hosmer-Lemeshow goodness-of-fit statistic, 0.74).

Conclusions— This study is the largest ever conducted for out-of-hospital cardiac arrest survivors, clearly shows that these patients have good quality of life, and is the first to demonstrate that citizen-initiated CPR is strongly and independently associated with better quality of life. These results emphasize the importance of optimizing community citizen CPR readiness. Given the low rate of citizen-initiated CPR in many communities, we believe that local and national initiatives should vigorously promote the practice of bystander CPR.

Optimal defibrillation response intervals for maximum out-of-hospital cardiac arrest survival rates

STUDY OBJECTIVE

Many centers optimize their emergency medical services (EMS) systems to achieve a target defibrillation response interval of "call received by dispatch" to "arrival at scene by responder with defibrillator" in 8 minutes or less for at least 90% of cardiac arrest cases. The objective of this study was to analyze survival as a function of time to test the evidence for this standard.

METHODS

This prospective cohort study included all adult, cardiac etiology, out-of-hospital cardiac arrest cases from phases I and II of the Ontario Prehospital Advanced Life Support (OPALS) study. Patients in the 21 Ontario study communities received a basic life support level of care with defibrillation by ambulance and firefighters but no advanced life support. Survival was plotted as a function of the defibrillation response interval. The equation of the curve, generated by means of logistic regression, was used to estimate survival at various defibrillation response interval cutoff points.

RESULTS

From January 1, 1991, to December 31, 1997, there were 392 (4.2%) survivors overall among the 9,273 patients treated. The defibrillation response interval mean was 6.2 minutes, and the 90th percentile was 9.3 minutes. There was a steep decrease in the first 5 minutes of the survival curve, beyond which the slope gradually leveled off. Controlling for known covariates, the decrement in the odds of survival with increasing response interval was 0.77 per minute (95% confidence interval 0.74 to 0.83). The survival function predicts, for successive 90th percentile cutoff points, both survival rates and additional lives saved per year in the OPALS communities compared with the 8-minute standard: 9 minutes (4.6%; -18 lives), 8 minutes (5.9%; 0 lives), 7 minutes (7.5%; 23 lives), 6 minutes (9.5%; 51 lives), and 5 minutes (12.0%; 86 lives).

CONCLUSION

The 8-minute target established in many communities is not supported by our data as the optimal EMS defibrillation response interval for cardiac arrest. EMS system leaders should consider the effect of decreasing the 90th percentile defibrillation response interval to less than 8 minutes.

Emergency system prospective performance evaluation for cardiac arrest in Lombardia, an Italian region

BACKGROUND

The aim of this research is to evaluate quality of out-of-hospital medical services in our country, using performance indicators and a new computerised database.

METHODS

(a)

EXPERIMENTAL DESIGN

Data were collected prospectively in three emergency dispatch centres for 90 days. Follow-up was evaluated at 1 day and 1 month after the event. This paper presents data on the cardiac arrest cohort only. (b)

SETTING

Three emergency dispatch centres in Lombardia. (c)

PATIENTS

One hundred and seventy-eight patients in non-traumatic cardiac arrest were enrolled. (d)

INTERVENTIONS

None. The study was observational only.

RESULTS

Mean interval between phone call and arrival on scene was 8.5+/-3.5 min. BLS manoeuvres were carried out from bystanders only in 15% of the cohort; this was associated with significant mortality reduction (85.7 versus 95.8%, chi(2) P<0.05). One hundred and thirty-three patients (75%) received assistance from BLS crews while only 45 patients (25%) were assisted by ALS medical personel, with a significant mortality reduction (ALS deaths 86.7%, BLS deaths 97%). Total 24 h survival was 9% and survival at 1 month declined to 6.17%.

CONCLUSIONS

Quality monitoring produces objective information on interventions and outcomes. Only with this information, is it possible to implement improvement programmes that are planned according to the data presented.

Prehospital ACLS--does it work?

Cardiac disease is the most common cause of death in the United States, and sudden cardiac arrest frequently claims the lives of men and women during their most productive years. It is believed that much better survival rates can be achieved for victims of cardiac arrest through optimizing the "chain of survival" as described by the American Heart Association. The relative and incremental benefit of full prehospital ACLS over basic life support and defibrillation is unproven, however. This is an important issue in this era of cost containment. Some of the ongoing studies including the OPALS study may clarify the cost effectiveness and relative efficacy of rapid defibrillation and full ACLS programs for victims of prehospital cardiac arrest [6].

Description of ambulance diversions in Edmonton region

Background:

Diversion of ambulances by hospital emergency departments has become a day-to-day occurrence in many jurisdictions within Canada. Yet, despite the increasing prevalence of this phenomenon, its impact on transported patients, on the EMS system, and on the health care system overall has not, to date, been well quantified. Despite the increasing sophistication and capabilities of North American EMS systems, it is difficult to argue with the principle that unstable or potentially unstable patients are best served by expeditious transport for definitive care to acute care facilities. T o this end, this study represents an effort to assess the systemic and patient care impacts of ambulance diversions.

Methods:

Patient-care and corresponding ambulance trip records for all patients transported by this EMS system for a five week period were abstracted to identify those patients in which an ambulance was diverted from its initial destination. Adverse events include hypotensive episodes, airway compromise, changes in level of consciousness, and the onset of violent behavior. Response and transport times also were abstracted, comparisons utilized student's t-test and 95% Confidence Intervals. Results: Ambulance diversions increased EMS response times and prehospital transport times. Adverse medical events occurred during 4.3% of diverted ambulance runs. Patients, when faced with the prospect of transport to other than their hospital of choice, not infrequently cancelled EMS transport and sought other means of transport. Subsequent interfacility transport was required for 4.3% of the diverted patients.

Conclusions:

Diversion of ambulances impacts the EMS system by increasing response and transport times; the region, by generating subsequent interfacility transports; and patients, as adverse medical events can occur during the diverted transport.

Use of the esophageal tracheal combitube by basic emergency medical technicians

The most appropriate airway device for use in EMS systems staffed by basic skilled EMTs with (EMT-Ds) or without (EMT-Bs) defibrillation capabilities is still a matter of debate. The purpose of this study was to assess the feasibility, safety and effectiveness of the Esophageal Tracheal Combitube (ETC) when used by EMT-Ds in cardiorespiratory arrest patients of all etiologies. The EMTs had automatic external defibrillator (AED) training but no prior advanced airway technique skills. The prehospital intervention was reviewed using the EMTs cardiac arrest report, the AED tape recording of the event and the assessment of the receiving emergency physician. The patients' hospital records and autopsy report were reviewed in search of complications. Eight hundred and thirty-one adult cardiac arrest patients were studied. Placement was successful in 725 (95.4%) of the 760 patients where it was attempted and ventilation was successful in 695 (91.4%). Immediate complications encountered, but not necessarily related to the use of the ETC, were; subcutaneous emphysema (18), tension pneumothorax (5), blood in the oropharynx (15), and swelling of the pharynx (three). An autopsy was done in 133 patients; no esophageal lesions or significant injury to the airway structures were observed. Our results suggest that EMT-Ds can use the ETC for control of the airway and ventilation in cardiorespiratory arrest patients safely and effectively.

Outcomes of out-of-hospital cardiac arrest patients in Perth, Western Australia, 1996-1999

STUDY OBJECTIVE

To describe the epidemiology and survival from out-of-hospital cardiac arrest.

DESIGN

Longitudinal follow-up study from the time of paramedic attendance to 12 months later.

SETTING

Perth, Western Australia (WA), a metropolitan capital city with an adult population of approximately one million people.

METHOD

The St John Ambulance Australia (WA Ambulance Service Incorporated) cardiac arrest database was linked to the WA hospital morbidity and mortality data using probabilistic matching.

INCIDENCE

Of 3730 cardiorespiratory arrests in 1996-1999, the age standardised rate of arrests of presumed cardiac origin, where resuscitation was attempted (n=1293) was 32.9 per 100000 person-years and 7.1 per 100000 person-years for bystander-witnessed VF/VT arrests.

SURVIVAL

Survival to 28 days was 6.8% following all bystander-witnessed cardiac arrests; 10.6% following bystander-witnessed VF/VT arrests and 33% for paramedic-witnessed cardiac arrests. Logistic regression analysis showed an inverse association between ambulance response time interval and survival following all bystander-witnessed cardiac arrests (and VF/VT arrests). ONE YEAR SURVIVAL: 89% of bystander-witnessed cardiac arrest survivors and 92% of paramedic-witnessed cardiac arrests were still alive at 1 year post-arrest.

CONCLUSION

The trends in occurrence and survival following out-of-hospital cardiac arrest in Perth, WA, are similar to those found elsewhere. There is an opportunity to strengthen the chain of survival by reducing the response time interval and increasing the use of bystander cardiopulmonary resuscitation (CPR). First-responder programs and public access defibrillation will need to be considered in the light of local demographics, location and the epidemiologic features of out-of-hospital cardiac arrest.