Ontario Prehospital Advanced Life Support Research Articles

Advanced Life Support for out-of-hospital Chest Pain: The Opals Study

ABSTRACT Context: As many as 14% of patients transported by ambulance with chest pain die prior to hospital discharge. To date, no high-quality controlled trials have revealed that prehospital advanced life support interventions affect survival for these patients. Objective: The Ontario Prehospital Advanced Life Support (OPALS) Study assessed the effect of adding an advance life support service to an existing basic life support emergency medical service program, on the rate of mortality and morbidity for patients with out-of-hospital chest pain. Design: Controlled clinical trial comparing survival for 9 months before and 9 after instituting an advanced life support program. Setting: Thirteen urban and suburban Ontario communities (populations ranging from 30,000 to 750,000; total, 2.5 million). Patients: All adult patients with a primary complaint of chest pain and transported by paramedics to the emergency department. Intervention: Paramedics were trained in standard advanced life support, which includes endotracheal intubation, intravenous furosemide and morphine, oral ASA, and sublingual NTG. Emergency medical services within each community had to meet predefined criteria in order to qualify for the advanced life support phase. Main Outcome Measure: Survival to hospital discharge. Results: Overall, 12,168 patients were enrolled in either the basic life support phase (N = 5,788) or the advanced life support phase (N = 6,380). The rate of mortality significantly decreased from 4.3% in the basic life support phase to 3.2% in the advanced life support phase (absolute change 1.1, 95% CI 0.4-1.8, P = 0.0013). We also demonstrated a decrease in mortality for the subgroup of patients with a discharge diagnosis of myocardial infarction (13.1 percent vs 8.2 percent, P = 0.002). Conclusions: The addition of a prehospital advanced life support program to an existing basic life support emergency medical service was associated with a significant decrease in the mortality rate among patients complaining of chest pain. Future research should clarify the most effective interventions and target specific populations. ClinicalTrials.gov Identifier: NCT00212953

Utility of prehospital electrocardiogram characteristics as prognostic markers in out-of-hospital pulseless electrical activity arrests

BackgroundIt is unclear if there are predictors of survival, including ECG characteristics, that can guide resuscitative efforts in pulseless electrical activity (PEA) cardiac arrests. We studied the predictive potential of...

The Pan-Asian Resuscitation Outcomes Study (PAROS) clinical research network: what, where, why and how.

Out-of-hospital cardiac arrest (OHCA) is a global health concern with an incidence rate of 50-60 per 100,000 person-years. To improve OHCA survival rates, several cardiac arrest registries have been set up in North America and Europe, such as the Resuscitation Outcomes Consortium, Cardiac Arrest Registry to Enhance Survival, Ontario Prehospital Advanced Life Support and European Registry of Cardiac Arrest. In Asia, however, there was previously no concerted effort in prehospital emergency care research owing to differences in prehospital emergency medical services systems, data collection methods and outcome reporting between countries. Recognising the need for a collaborative prehospital emergency care research group in Asia, researchers from seven countries in the Asia-Pacific region (including Japan, South Korea, Taiwan, Thailand, United Arab Emirates-Dubai, Singapore and Malaysia) established the Pan-Asian Resuscitation Outcomes Study (PAROS) clinical research network in 2010. This paper gives the overview, methodology and research accomplishments of the PAROS network.

Differential survival for men and women from out-of-hospital cardiac arrest varies by age: results from the OPALS study.

The effect of sex on survival in out-of-hospital cardiac arrest (OHCA) is controversial. Some studies report more favorable outcomes in women, while others suggest the opposite, citing disparities in care. Whether sex predicts differential age-specific survival is still uncertain. The objective was to study the sex-associated variation in survival to hospital discharge in OHCA patients as well as the relationship between age and sex for predicting survival. The Ontario Prehospital Advanced Life Support (OPALS) registry, collected in a large study of rapid defibrillation and advanced life support programs, is Utstein-compliant and has data on OHCA patients (1994 to 2002) from 20 communities in Ontario, Canada. All adult OHCAs not witnessed by emergency medical services (EMS) and treated during one of the three main OPALS phases were included. Clinically significant variables were chosen a priori (age, sex, witnessed arrest, initial cardiopulmonary resuscitation [CPR], shockable rhythm, EMS response interval, and OPALS study phase) and entered into a multivariable logistic regression model with survival to hospital discharge as the outcome, with sex and age as the primary risk factors. Fractional polynomials were used to explore the relationship between age and survival by sex. A total of 11,479 (out of 20,695) OPALS cases met inclusion criteria and 10,862 (94.6%) had complete data for regression analysis. As a group, women were older than men (median age = 74 years vs. 69 years, p < 0.01), had fewer witnessed arrests (43% vs. 49%; p < 0.01), had fewer initial ventricular fibrillation/ventricular tachycardia rhythms (24% vs. 42%; p < 0.01), had a lower rate of bystander CPR (12% vs. 17%; p < 0.01), and had lower survival (1.7% vs. 3.2%; p < 0.01). Survival to hospital admission and return of spontaneous circulation did not differ between women and men (p > 0.05). The relationship between age, sex, and survival to hospital discharge could not be analyzed in a single regression model, as age did not have a linear relationship with survival for men, but did for women. Thus, age was kept as a continuous variable for women but was transformed for men using fractional polynomials [ln(age) + age(3) ]. In sex-stratified regression models, the adjusted probability of survival for women decreased as age increased (adjusted odds ratio = 0.88, 95% confidence interval = 0.81 to 0.96, per 5-year increase in age) while for men, the probability of survival initially increased with age until age 65 years and then decreased with increasing age. Women had a higher probability of survival until age 47 years, after which men maintained a higher probability of survival. Overall OHCA survival for women was lower than for men in the OPALS study. Factors related to the sex differences in survival (rates of bystander CPR and shockable rhythms) may be modifiable. The probability of survival differed across age for men and women in a nonlinear fashion. This differential influence of age on survival for men and women should be considered in future studies evaluating survival by sex in OHCA population.

In reply: Is out-of-hospital intubation by paramedics valid enough to be continued?

To the Editor:As Dr. Morita and his colleagues describe in their Letterto the Editor, many recent studies have shown that out-of-hospital intubation is associated with decreased survival[1–3]. However, there are differences in the medicalbackground of the endotracheal intubation (ETI) performedin these studies and our study.The incidence of ETI attempted by paramedics in thereported studies was extremely high ([80%) in the USA[1–3], with ETI attempted in patients with a difficult air-way or with a Cormack grade of C2[2]. In the regioncovered by our study, ETI is not permitted as a routineprocedure for patients with out-of-hospital cardiac arrest(OHCA). In addition, ETI attempts are terminated whenthe Cormack grade of patient is C2.The etiology of cardiac arrest may have differedbetween the patients in our study and those of the otherstudies. In none of the three studies [1–3] did the patientsshow an etiology of cardiac arrest. Approximately 60–70%of cardiac arrest is related to coronary heart disease in theUSA [4]. In our study, we showed that implementation ofETI may worsen the outcomes in OHCA patients with acardiac etiology, but they may improve the outcomes inOHCA patients without a noncardiac etiology.Finally, ETI was repeatedly attempted by paramedics inthe USA [2]. In our region, only two attempts are made.The interruption of chest compression accompanying theETI was set at\30 s prior to November 2006 and at\10 sthereafter.The Ontario pre-hospital advanced life support(OPALS) respiratory distress study showed that the intro-duction of an EMS advanced-life-support program signif-icantly reduced the mortality of patients with shortness ofbreath [5]. Japanese paramedics are allowed to performETI immediately after they witness a cardiac arrest. Webelieve that effectiveness of ETI should be prospectivelyevaluated in OHCAs that occur following the arrival of theparamedic.In our study, we excluded 124 patients in whomadvanced airway management (AAM) was discontinued orfailed. Of these 124 patients, 52 were managed by non-certified paramedics and did not include cases of attemptedETI. In the remaining 72 patients, certified paramedicsattempted either ETI or another AAM procedure, or both.Therefore, the 124 patients varied widely in terms of AAMprocedure and were justifiably excluded from the analysis.The AAM procedure was more frequently attempted bycertified paramedics. However, we showed that manage-ment by paramedics qualified for ETI was not independentfactor associated with sustained return of spontaneouscirculation.More than 50 or 60 intubations may be necessary toachieve a 90% success rate when the ETI is attemptedwithout considering the Cormack. According to a pre-liminary analysis in our region, after paramedics have had15 consecutive cases with Cormack grade of 1, the successrate in the following ten cases exceeds 95%. The trainingprograms are considered to be appropriate for the patientswith a Cormack grade of 1.The harm caused by ETI should be minimized by edu-cation and continuous quality assurance. In our region, arecertification program for certified paramedics has been

Commentary: Making a Difference in Emergency Medical Services

Commentary: Making a Difference in Emergency Medical Services

Public Access Defibrillation

Sudden cardiac arrest (SCA) is recognized as a serious public health problem, accounting for 250 000 to 300 000 deaths per year; it is now the third-leading cause of death behind cancer and nonsudden cardiovascular deaths.1,2 Immediate, well-performed cardiopulmonary resuscitation (CPR) and early defibrillation are the only out-of-hospital interventions that improve outcomes.3 The chain of survival relies on lay responders and emergency medical services (EMS) to initiate the potentially life-saving procedures of CPR and defibrillation. Articles see pp 510 and 518 In 1994, the American Heart Association (AHA) convened the first conference on public access defibrillation (PAD) to introduce the strategy of placing easy-to-use defibrillators in public places to decrease the death rate from SCA.4 Specific recommendations encouraged the stakeholders (the AHA, the US Food and Drug Administration, the National Institutes of Health, industry, and communities) to facilitate PAD by developing user-friendly, less-expensive automated external defibrillators (AEDs); testing the concept within large clinical trials; and organizing communities to promote and support effective PAD programs. Widespread CPR and AED training of the public was emphasized. In the ensuing 15 years, many of these recommendations have been heeded, and PAD programs are now commonplace. The National Institutes of Health–sponsored PAD trial demonstrated that survival doubled when events occurred in communities equipped and trained with CPR and AEDs compared with CPR alone.5 Within the Resuscitations Outcomes Consortium (ROC), out-of-hospital cardiac arrest victims had a markedly increased chance of survival if the first shock was delivered by a bystander using an AED rather than by EMS.6 PAD programs in airports, airlines, and casinos have also validated the effectiveness of the concept. Out-of hospital cardiac arrest is treatable, and outcomes can be improved with currently available approaches. Multiple locations have been recognized as having a higher incidence of cardiac arrest …

Effect of Transport Interval on Out-of-Hospital Cardiac Arrest Survival in the OPALS Study: Implications for Triaging Patients to Specialized Cardiac Arrest Centers

To identify any association between out-of-hospital transport interval and survival to hospital discharge in victims of out-of-hospital cardiac arrest. Data from the Ontario Prehospital Advanced Life Support Study (January 1, 1991, to December 31, 2002), an Utstein-compliant registry of out-of-hospital cardiac arrest patients from 21 communities, were analyzed. Logistic regression identified factors that were independently associated with survival in consecutive adult, nontraumatic, out-of-hospital cardiac arrest patients and in the subgroup with return of spontaneous circulation. A total of 18,987 patients met criteria and 15,559 (81.9%) had complete data for analysis (study group). Return of spontaneous circulation was achieved in 2,299 patients (14.8%), and 689 (4.4%) survived to hospital discharge. Median transport interval was 4.0 minutes (25th quartile 3.0 minutes; 75th quartile 6.2 minutes) for survivors and 4.2 minutes (25th quartile 3.0, 75th quartile 6.2) for nonsurvivors. Logistic regression revealed multiple factors that were independently associated with survival: witnessed arrest (odds ratio 2.61; 95% confidence interval [CI] 2.05 to 3.34), bystander cardiopulmonary resuscitation (odds ratio 2.22; 95% CI 1.82 to 2.70), initial rhythm of ventricular fibrillation/tachycardia (odds ratio 2.22; 95% CI 1.97 to 2.50), and shorter emergency medical services (EMS) response interval (odds ratio 1.26; 95% CI 1.20 to 1.33). There was no association between transport interval and survival in either the study group (odds ratio 1.01; 95% CI 0.99 to 1.05) or the return of spontaneous circulation subgroup (odds ratio 1.04; 95% CI 0.99, 1.08). In a large out-of-hospital cardiac arrest study from demographically diverse EMS systems, longer transport interval was not associated with decreased survival. Given the growing evidence showing major influence from specialized postarrest care, these findings support conducting clinical trials that assess the effectiveness and safety of bypassing local hospitals to take patients to regional cardiac arrest centers.

Post–Cardiac Arrest Syndrome

The contributors to this statement were selected to ensure expertise in all the disciplines relevant to post–cardiac arrest care. In an attempt to make this document universally applicable and generalizable, the authorship comprised clinicians and scientists who represent many specialties in many regions of the world. Several major professional groups whose practice is relevant to post–cardiac arrest care were asked and agreed to provide representative contributors. Planning and invitations took place initially by e-mail, followed a series of telephone conferences and face-to-face meetings of the cochairs and writing group members. International writing teams were formed to generate the content of each section, which corresponded to the major subheadings of the final document. Two team leaders from different countries led each writing team. Individual contributors were assigned by the writing group cochairs to work on 1 or more writing teams, which generally reflected their areas of expertise. Relevant articles were identified with PubMed, EMBASE, and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Drafts of each section were written and agreed on by the writing team authors and then sent to the cochairs for editing and amalgamation into a single document. The first draft of the complete document was circulated among writing team leaders for initial comment and editing. A revised version of the document was circulated among all contributors, and consensus was achieved before submission of the final version for independent peer review and approval for publication. This scientific statement outlines current understanding and identifies knowledge gaps in the pathophysiology, treatment, and prognosis of patients who regain spontaneous circulation after cardiac arrest. The purpose is to provide a resource for optimization of post–cardiac arrest care and to pinpoint the need for research focused on gaps in knowledge that would potentially improve outcomes …

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

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. 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. 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). 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.

Comparison of the Cerebral Performance Category Score and the Health Utilities Index for Survivors of Cardiac Arrest

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. 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). 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. 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.

Reducing Barriers for Implementation of Bystander-Initiated Cardiopulmonary Resuscitation

Sudden cardiac arrest (SCA) is a leading cause of death in the United States and Canada. In the United States, each year ≈330 000 people die of coronary heart disease out of the hospital or in emergency departments. Of these, >150 000 SCAs occur out of the hospital.1,2 Despite the development of electrical defibrillation and the more recent implementation of lay rescuer defibrillation programs, the vast majority of these victims do not leave the hospital alive. In studies over the past 15 years, only 1.4% of patients with out-of-hospital arrest in Los Angeles, Calif, survived to hospital discharge3; in Chicago, Ill, the number was 2%,4 and in Detroit, Mich, it was <1%.5 Conversely, a few municipalities such as Seattle, Wash, report much higher survival rates from SCA—more than 15% in 1 study6—which suggests that survival rates need not remain so low. Recent work in Europe and elsewhere has confirmed that a higher survival-to-hospital discharge rate is indeed a realistic goal, with survival rates as high as 9% reported in Amsterdam7 and 21% in Maribor, Slovenia.8 The American Heart Association (AHA) uses 4 links in the “chain of survival” to illustrate the time-sensitive actions required for victims of SCA: (1) early recognition of the emergency and activation of emergency medical services (EMS), (2) early bystander cardiopulmonary resuscitation (CPR), (3) early delivery of shock(s) from a defibrillator if indicated, and (4) early advanced life support and postresuscitation care. Immediate bystander recognition of the emergency and EMS activation are critical. In many communities, however, these actions may be followed by significant delays, because the time interval from activation of EMS to arrival of these medical personnel may be 7 to 8 minutes or longer.4 Therefore, initial care in the first critical minutes after …

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

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. 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. 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%). 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?

Pediatric cardiopulmonary arrest (CPA) outside of the hospital has a very high mortality rate. To evaluate the etiology and initial compromise of pediatric CPA cases in hopes of developing strategies to improve out-of-hospital resuscitation. 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. 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%. 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.

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

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

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

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. 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. 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. 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.

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

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. 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. 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). 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.

Initial Emergency Department Trauma Scores from the OPALS Study: The Case for the Motor Score in Blunt Trauma

Abstract Objectives: To compare the predictive accuracy of the Revised Trauma Score (RTS), the Glasgow Coma Scale (GCS), and their components in blunt trauma patients. Methods:This multicenter prospective cohort study was conducted in 20 communities as part of the Ontario Prehospital Advanced Life Support (OPALS) Study. It included adult trauma patients with Injury Severity Scores &gt;12. The assessments made by trauma team leaders for the RTS, GCS, and their subscales were analyzed: 1) receiver operating characteristic (ROC) curve areas and Kendall's tau c correlation coefficient (Tc) for survival to hospital discharge, 2) Mann‐Whitney U test and Tc correlations for intensive care unit admission, and 3) Spearman correlations with the disability measure Glasgow Outcome Scale. Results: The authors analyzed data from 795 blunt trauma patients with these characteristics: median age of 40 years, 70% male, and 18% mortality. The scores that best predicted survival were the RTS (ROC = 0.83, Tc = 0.39), the GCS (ROC = 0.82, Tc = 0.38), the motor component of the GCS (ROC = 0.81, Tc = 0.37), and the verbal component of the GCS (ROC = 0.81, Tc = 0.36). Only scores for the RTS (p = 0.03), the GCS (p = 0.02), and the motor component of the GCS (p = 0.03) showed a significant association with admission to the intensive care unit. The associations with disability were weak in all scores. Conclusions: The initial emergency department motor score showed the highest predictive validity among all of the other components. These results suggest its validity for blunt trauma triage when compared with the GCS or RTS.

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. [Ann Emerg Med. 2003;42:242-250.]

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

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. 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. 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). 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.