Alan M. Craig

Out-of-hospital cardiac arrest survival improving over time: Results from the Resuscitation Outcomes Consortium (ROC).

BACKGROUND Out-of-hospital cardiac arrest (OHCA) remains a leading cause of death and a 2010 meta-analysis concluded that outcomes have not improved over several decades. However, guidelines have changed to emphasize CPR quality, minimization of interruptions, and standardized post-resuscitation care. We sought to evaluate whether OHCA outcomes have improved over time among agencies participating in the Resuscitation Outcomes Consortium (ROC) cardiac arrest registry (Epistry) and randomized clinical trials (RCTs). METHODS Observational cohort study of 47,148 EMS-treated OHCA cases in Epistry from 139 EMS agencies at 10 ROC sites that participated in at least one RCT between 1/1/2006 and 12/31/2010. We reviewed patient, scene, event characteristics, and outcomes of EMS-treated OHCA over time, including subgroups with initial rhythm of pulseless ventricular tachycardia or ventricular fibrillation (VT/VF). RESULTS Mean response interval, median age and male proportion remained similar over time. Unadjusted survival to discharge increased between 2006 and 2010 for treated OHCA (from 8.2% to 10.4%), as well as for subgroups of VT/VF (21.4% to 29.3%) and bystander witnessed VT/VF (23.5% to 30.3%). Compared with 2006, adjusted survival to discharge was significantly higher in 2010 for treated cases (OR = 1.72; 95% CI 1.53, 1.94), VT/VF cases (OR = 1.69; 95% CI 1.45, 1.98) and bystander witnessed VT/VF cases (OR = 1.65; 95% CI 1.36, 2.00). Tests for trend in each subgroup were significant (p < 0.001). CONCLUSIONS ROC-wide survival increased significantly between 2006 and 2010. Additional research efforts are warranted to identify specific factors associated with this improvement.

A Trial of an Impedance Threshold Device in Out-of-Hospital Cardiac Arrest

BACKGROUND The impedance threshold device (ITD) is designed to enhance venous return and cardiac output during cardiopulmonary resuscitation (CPR) by increasing the degree of negative intrathoracic pressure. Previous studies have suggested that the use of an ITD during CPR may improve survival rates after cardiac arrest. METHODS We compared the use of an active ITD with that of a sham ITD in patients with out-of-hospital cardiac arrest who underwent standard CPR at 10 sites in the United States and Canada. Patients, investigators, study coordinators, and all care providers were unaware of the treatment assignments. The primary outcome was survival to hospital discharge with satisfactory function (i.e., a score of ≤3 on the modified Rankin scale, which ranges from 0 to 6, with higher scores indicating greater disability). RESULTS Of 8718 patients included in the analysis, 4345 were randomly assigned to treatment with a sham ITD and 4373 to treatment with an active device. A total of 260 patients (6.0%) in the sham-ITD group and 254 patients (5.8%) in the active-ITD group met the primary outcome (risk difference adjusted for sequential monitoring, -0.1 percentage points; 95% confidence interval, -1.1 to 0.8; P=0.71). There were also no significant differences in the secondary outcomes, including rates of return of spontaneous circulation on arrival at the emergency department, survival to hospital admission, and survival to hospital discharge. CONCLUSIONS Use of the ITD did not significantly improve survival with satisfactory function among patients with out-of-hospital cardiac arrest receiving standard CPR. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.).

A descriptive analysis of emergency medical service systems participating in the Resuscitation Outcomes Consortium (ROC) network

Background. The optimal Emergency Medical Services (EMS) system characteristics have not been defined, resulting in substantial variability across systems. The Resuscitation Outcomes Consortium (ROC) is a United States-Canada research network that organized EMS agencies from 11 different systems to perform controlled trials in cardiac arrest andlife-threatening trauma resuscitation. Objectives. To describe EMS systems participating in ROC using a novel framework. Methods. Standardized surveys were created by ROC investigators anddistributed to each site for completion. These included separate questions for individual hospitals, EMS agencies, anddispatch centers. Results were collated andanalyzed by using descriptive statistics. Results. A total of 264 EMS agencies, 287 hospitals, and154 dispatch centers were included. Agencies were described with respect to the type (fire-based, non-fire governmental, private), transport status (transport/non-transport), andtraining level (BLS/ALS). Hospitals were described with regard to their trauma designation andthe presence of electrophysiology andcardiac catheterization laboratories. Dispatch center characteristics, including primary versus secondary public safety answering point (PSAP) status andthe use of prearrival instructions, were also described. Differences in EMS system characteristics between ROC sites were observed with multiple intriguing patterns. Rural areas andfire-based agencies had more EMS units andproviders per capita. This may reflect longer response andtransport distances in rural areas andthe additional duties of most fire-based providers. In addition, hospitals in the United States typically had catheterization laboratories, whereas Canadian hospitals generally did not. The vast majority of both primary andsecondary PSAPs use computer-aided dispatch. Conclusions. Similarities anddifferences among EMS systems participating in the ROC network were described. The framework used in this analysis may serve as a template for future EMS research.

Increased survival after EMS witnessed cardiac arrest. Observations from the Resuscitation Outcomes Consortium (ROC) Epistry-Cardiac arrest.

BACKGROUND Out of hospital cardiac arrest (OHCA) is common and lethal. It has been suggested that OHCA witnessed by EMS providers is a predictor of survival because advanced help is immediately available. We examined EMS witnessed OHCA from the Resuscitation Outcomes Consortium (ROC) to determine the effect of EMS witnessed vs. bystander witnessed and unwitnessed OHCA. METHODS Data were analyzed from a prospective, population-based cohort study in 10 U.S. and Canadian ROC sites. Individuals with non-traumatic OHCA treated 04/01/06-03/31/07 by EMS providers with defibrillation or chest compressions were included. Cases were grouped into EMS-witnessed, bystander witnessed, and unwitnessed and further stratified for bystander CPR. Multiple logistic regressions evaluated the odds ratio (OR) for survival to discharge relative to the EMS-witnessed group after adjusting for age, sex, public/private location of collapse, ROC site, and initial ECG rhythm. Of 9991 OHCA, 1022 (10.2%) of EMS-witnessed, 3369 (33.7%) bystander witnessed, and 5600 (56.1%) unwitnessed. RESULTS The most common initial rhythm in the EMS-witnessed group was PEA which was higher than in the bystander- and unwitnessed groups (p<0.001). The adjusted OR (95% CI) of survival compared to the EMS-witnessed group was 0.41, (0.36, 0.46) in bystander witnessed with bystander CPR, 0.37 (0.33, 0.43) in bystander witnessed without bystander CPR, 0.17 (0.14, 0.20) in unwitnessed with bystander CPR and 0.21 (0.18, 0.24) in unwitnessed cases without bystander CPR. CONCLUSIONS Immediate application of prehospital care for OHCA may improve survival. Efforts should be made to educate patients to access 9-1-1 for prodromal symptoms.

The relationship between temperature and ambulance response calls for heat-related illness in Toronto, Ontario, 2005.

Background Concern over the adverse effects of heat on human health has led to numerous studies assessing the relationship between heat and mortality. Few studies have quantified the impact of heat on morbidity, including ambulance response calls. This study describes the association between temperature and ambulance response calls for heat-related illness (HRI) in Toronto, Ontario, Canada during the summer of 2005. Methods Data sources included daily temperature, relative humidity and humidex information from Environment Canada, and Medical Priority Dispatch System data from Toronto Emergency Medical Services. Time series and regression analyses were used to examine the relationship between daily temperature and ambulance response calls for HRI during the summer (1 June to 31 August) of 2005. Results In 2005, there were 201 ambulance response calls for HRI. On average, for every one degree increase in maximum temperature (°C) there was a 29% increase in ambulance response calls for HRI (p<0.0001). For every one degree increase in mean temperature (°C) there was a 32% increase in ambulance response calls for HRI (p<0.0001). Conclusions Given these associations, we urge further exploration of ambulance response calls as a source of HRI morbidity data particularly given the increasing health concerns associated with climate change.

Temporal and spatial variation of heat-related illness using 911 medical dispatch data.

BACKGROUND The adverse effect of hot weather on health in urban communities is of increasing public health concern, particularly given trends in climate change. OBJECTIVES To demonstrate the potential public health applications of monitoring 911 medical dispatch data for heat-related illness (HRI), using historical data for the summer periods (June 1-August 31) during 2002-2005 in Toronto, Ontario, Canada. METHODS The temporal distribution of the medical dispatch calls was described in relation to a current early warning system and emergency department data from the National Ambulatory Care Reporting System (NACRS). Geospatial methods were used to map the percentage of heat-related calls in each Toronto neighborhood over the study period. RESULTS The temporal pattern of 911 calls for HRI was similar, and sometimes peaked earlier, than current heat health warning systems (HHWS). The pattern of calls was similar to NACRS HRI visits, with the exception of 2005 where 911 calls peaked earlier. Areas of the city with a relatively higher burden of HRI included low income inner-city neighborhoods, areas with high rates of street-involved individuals, and areas along the waterfront which include summer outdoor recreational activities. CONCLUSIONS Identifying the temporal trends and geospatial patterns of these important environmental health events has the potential to direct targeted public health interventions to mitigate associated morbidity and mortality.

The Impact of Distance on Triage to Trauma Center Care in an Urban Trauma System

Abstract Background. Urban trauma systems are characterized by high population density, availability of trauma centers, and acceptable road transport times (within 30 minutes). In such systems, patients meeting field trauma triage (FTT) criteria should be transported directly to a trauma center, bypassing closer non–trauma centers. Objective. We evaluated emergency medical services (EMS) triage practices to identify opportunities for improving care delivery. Objective. Specifically, we evaluated the effect of the additional distance to a trauma center, compared with a closer non–trauma center, on the noncompliance with trauma destination criteria by EMS personnel in an urban environment. Methods. This was a retrospective cohort study of adults having at least one physiologic derangement and meeting Toronto EMS field trauma triage criteria from 2005 to 2010. Road travel distances between the site of injury, the closest non–trauma center, and the closest trauma center were estimated using geographic information systems. For patients who were transported to non–trauma centers, we estimated “differential distance”: the additional travel distance required to transport directly to a trauma center. Logistic regression was used to analyze the effect of differential distance on triage decisions, adjusting for other patient characteristics. Results. Inclusion criteria identified 898 patients; 53% were transported directly to a trauma center. Falls, female gender, and age greater than 65 years were associated with transport to non–trauma centers. Differential distances greater than 1 mile were associated with a decreased likelihood of triage to a trauma center. Conclusion. Differential distance between the closest non–trauma center and the closest trauma center was associated with lower compliance with triage protocols, even in an urban setting where trauma centers can be accessed within approximately 30 minutes. Our findings suggest that there are opportunities for reducing the gap between ideal and actual application of field trauma triage guidelines through a process of education and feedback.

Serial Prehospital 12-Lead Electrocardiograms Increase Identification of ST-segment Elevation Myocardial Infarction

Abstract Background. Many prehospital protocols require acquisition of a single 12-lead electrocardiogram (ECG) when assessing a patient for ST-segment elevation myocardial infarction (STEMI). However, it is known that ECG evidence of STEMI can evolve over time. Objectives. To determine how often the first and, if necessary, second or third prehospital ECGs identified STEMI, and the time intervals associated with acquiring these ECGs and arrival at the emergency department (ED). Methods. We retrospectively analyzed 325 consecutive prehospital STEMIs identified between June 2008 and May 2009 in a large third-service emergency medical services (EMS) system. If the first ECG did not identify STEMI, protocol required a second ECG just before transport and, if necessary, a third ECG before entering the receiving ED. Paramedics who identified STEMI at any time bypassed participating local EDs, taking patients directly to the percutaneous coronary intervention (PCI) center. Paramedics used computerized ECG interpretation with STEMI diagnosis defined as an “acute MI” report by GE/Marquette 12-SL software in ZOLL E-series defibrillator/cardiac monitors (ZOLL Medical, Chelmsford, MA). We recorded the time of each ECG, and the ordinal number of the diagnostic ECG. We then determined the number of cases and frequency of STEMI diagnosis on the first, second, or third ECG. We also measured the interval between ECGs and the interval from the initial positive ECG to arrival at the ED. Results. STEMI was identified on the first prehospital ECG in 275 cases, on the second ECG in 30 cases, and on the third ECG in 20 cases (cumulative percentages of 84.6%, 93.8%, and 100%, respectively). For STEMIs identified on the second or third ECG, 90% were identified within 25 minutes after the first ECG. The median times from identification of STEMI to arrival at the ED were 17.5 minutes, 11.0 minutes, and 0.7 minutes for STEMIs identified on the first, second, and third ECGs, respectively. Conclusions. A single prehospital ECG would have identified only 84.6% of STEMI patients. This suggests caution using a single prehospital ECG to rule out STEMI. Three serial ECGs acquired over 25 minutes is feasible and may be valuable in maximizing prehospital diagnostic yield, particularly where emergent access to PCI exists. Key words: prehospital emergency care; myocardial infarction; ECG; STEMI

Clinical Events and Treatment in Prehospital Patients with ST-segment Elevation Myocardial Infarction

Abstract Background. Little is known about clinically important events and advanced care treatment that patients with ST-segment elevation myocardial infarction (STEMI) encounter in the prehospital setting. Objectives. We sought to determine the proportion of community patients with STEMI who experienced a clinically important event or received advanced care treatment prior to arrival at a designated percutaneous coronary intervention (PCI) laboratory or emergency department (ED). Methods. We reviewed 487 consecutive community patients with STEMI between May 2008 and June 2009. All patients were geographically within a single large “third-service” urban emergency medical services (EMS) system and were transported by paramedics with an advanced care scope of practice. We recorded predefined clinically important events and advanced care treatment that occurred in patients being transported directly to a PCI laboratory or ED (group 1) or interfacility transfer to a PCI laboratory (group 2). Results. One or more clinically important events occurred in 92 of 342 (26.9%) group 1 patients and nine of 145 (6.2%) group 2 patients. The most common were sinus bradycardia, hypotension, and cardiac arrest. Additionally, 33 of 342 (9.6%) group 1 and nine of 145 (6.2%) group 2 patients received one or more advanced care treatments. The most common were administration of morphine and administration of atropine. Eight group 1 patients and three group 2 patients received cardiopulmonary resuscitation (CPR) or defibrillation. Conclusions. Clinically important events and advanced care treatment are common in community STEMI patients undergoing prehospital transport or interfacility transfer to a PCI center. Several patients required CPR or defibrillation. Further research is needed to define the clinical experience of STEMI patients during the out-of-hospital phase and the scope of practice required of EMS providers to safely manage these patients. Key words: myocardial infarction; complications; emergency medical services; emergency treatment

Evidence-based optimization of urban firefighter first response to emergency medical services 9-1-1 incidents

Abstract Introduction. Many emergency medical services (EMS) systems dispatch nonparamedic firefighter first responders (FFRs) to selected EMS 9-1-1 calls, intending to deliver time-sensitive interventions such as defibrillation, cardiopulmonary resuscitation (CPR), and bag–mask ventilation prior to arrival of paramedics. Deciding when to send FFRs is complicated because critical cases are rare, paramedics often arrive before FFRs, and lights-and-siren responses by emergency vehicles are associated with the risk of en-route traffic collisions. Objective. To describe a methodology allowing EMS systems to optimize their own FFR programs using local data, and reflecting local medical oversight policy and local risk–benefit opinion. Methods. We constructed a generalized input–output model that retrospectively reviews EMS dispatch and electronic prehospital clinical records to identify a subset of Medical Priority Dispatch System (MPDS) call categories (“determinants”) that maximize the opportunities for FFR interventions while minimizing unwarranted responses. Input parameters include local FFR interventions, the local FFR “first-on-scene” rate, and the locally acceptable ratio of risk to benefit. The model uses a receiver-operating characteristic (ROC) curve to identify the optimal mix of response specificity and sensitivity achieved by sending FFRs to progressively more categories of EMS calls while remaining within a defined risk–benefit ratio. The model was applied to a 16-month retrospective sample of 220,358 incidents from a large urban EMS system to compare the models recommendations with the systems current practices. Results. The model predicts that FFR lights-and-siren responses in the sample could be reduced by 83%, from 93,058 to 16,091 incidents, by confining FFR responses to 27 of 509 MPDS dispatch determinants, representing 7.3% of incidents but 58.9% of all predicted FFR interventions. Of the 93,058 incidents, another 58,275 incidents could be downgraded to safer nonemergency FFR responses and 18,692 responses could be eliminated entirely, improving the specificity of FFR response from 57.8% to 93.0%. Conclusions. This model provides a robust generalized methodology allowing EMS systems to optimize FFR lights-and-siren responses to emergency medical calls. Further validation is warranted to assess the models generality.