Early coronary angiography and induced hypothermia are associated with survival and functional recovery after out-of-hospital cardiac arrest

BACKGROUND

The rate and effect of coronary interventions and induced hypothermia after out-of-hospital cardiac arrest (OHCA) are unknown. We measured the association of early (≤24h after arrival) coronary angiography, reperfusion, and induced hypothermia with favorable outcome after OHCA.

METHODS

We performed a secondary analysis of a multicenter clinical trial (NCT00394706) conducted between 2007 and 2009 in 10 North American regions. Subjects were adults (≥18 years) hospitalized after OHCA with pulses sustained ≥60min. We measured the association of early coronary catheterization, percutaneous coronary intervention, fibrinolysis, and induced hypothermia with survival to hospital discharge with favorable functional status (modified Rankin Score≤3).

RESULTS

From 16,875 OHCA subjects, 3981 (23.6%) arrived at 151 hospitals with sustained pulses. 1317 (33.1%) survived to hospital discharge, with 1006 (25.3%) favorable outcomes. Rates of early coronary catheterization (19.2%), coronary reperfusion (17.7%) or induced hypothermia (39.3%) varied among hospitals, and were higher in hospitals treating more subjects per year. Odds of survival and favorable outcome increased with hospital volume (per 5 subjects/year OR 1.06; 95%CI: 1.04-1.08 and OR 1.06; 95%CI: 1.04, 1.08, respectively). Survival and favorable outcome were independently associated with early coronary angiography (OR 1.69; 95%CI 1.06-2.70 and OR 1.87; 95%CI 1.15-3.04), coronary reperfusion (OR 1.94; 95%CI 1.34-2.82 and OR 2.14; 95%CI 1.46-3.14), and induced hypothermia (OR 1.36; 95%CI 1.01-1.83 and OR 1.42; 95%CI 1.04-1.94).

INTERPRETATION

Early coronary intervention and induced hypothermia are associated with favorable outcome and are more frequent in hospitals that treat higher numbers of OHCA subjects per year.

The epidemiology and outcome of prehospital respiratory distress

OBJECTIVES

Patients with respiratory distress often seek emergency medical care and are transported by emergency medical services (EMS). EMS encounters with patients in respiratory distress have not been well described. The study objective was to characterize the epidemiology of prehospital respiratory distress and subsequent patient outcomes.

METHODS

This was a population-based cohort study of noninjured adults transported by EMS to any of 16 hospitals between 2002 and 2006. EMS records were linked to hospital administrative data for encounters categorized by EMS personnel as primarily "respiratory distress" in nature. The authors described prehospital patient and encounter characteristics, interventions, hospital discharge diagnoses (using ICD-9-CM codes), and patient outcomes. The association between prehospital variables, defined a priori, and hospital admission were described using multivariable logistic regression.

RESULTS

There were 166,908 EMS encounters, of which 19,858 were for respiratory distress (11.9%, 95% confidence interval [CI] = 11.7% to 12.1%). Half of the patients were admitted to the hospital (n = 9,964), one-third of those required intensive care (n = 3,094), and 10% of hospitalized patients died prior to discharge (n = 948). Fifteen percent of hospitalized patients received invasive mechanical ventilation (n = 1,501), over half of whom were intubated during prehospital care (n = 896). The most common primary discharge diagnoses among prehospital respiratory distress patients admitted to the hospital were congestive heart failure (CHF; 16%), pneumonia (15%), chronic obstructive pulmonary disease (COPD; 13%), and acute respiratory failure (13%). Few EMS patients with respiratory distress were coded with a primary diagnosis of acute myocardial infarction (3.5%, n = 350) or underwent percutaneous coronary intervention (0.7%, n = 71). In a multivariable regression model, prehospital factors that were independently associated with hospital admission included initial respiratory rate (odds ratio [OR] = 1.29 for an increase in respiratory rate of five breaths/min, 95% CI = 1.24 to 1.35) and an encounter that originated at a nursing home (OR = 2.80, 95% CI = 2.28 to 3.43).

CONCLUSIONS

In a population-based cohort, EMS personnel commonly encounter prehospital respiratory distress among medical patients, many of whom require hospital admission to the intensive care unit. These data may help to inform targeted therapy or more efficient triage and transport decisions.

Common variation in fatty acid metabolic genes and risk of incident sudden cardiac arrest

BACKGROUND

There is limited information on genetic factors associated with sudden cardiac arrest (SCA).

OBJECTIVE

To assess the association of common variation in genes in fatty acid pathways with SCA risk.

METHODS

We selected 85 candidate genes and 1155 single nucleotide polymorphisms (SNPs) tagging common variation in each gene. We investigated the SNP associations with SCA in a population-based case-control study. Cases (n = 2160) were from a repository of SCA in the greater Seattle area. Controls (n = 2615), frequency-matched on age and sex, were from the same area. We used linear logistic regression to examine SNP associations with SCA. We performed permutation-based p-min tests to account for multiple comparisons within each gene. The SNP associations with a corrected P value of <.05 were then examined in a meta-analysis of these SNP associations in 9 replication studies totaling 2129 SCA cases and 23,833 noncases.

RESULTS

Eight SNPs in or near 8 genes were associated with SCA risk in the discovery study, one of which was nominally significant in the replication phase (rs7737692, minor allele frequency 36%, near the LPCAT1 gene). For each copy of the minor allele, rs7737692 was associated with 13% lower SCA risk (95% confidence interval -21% to -5%) in the discovery phase and 9% lower SCA risk (95% confidence interval -16% to -1%) in the replication phase.

CONCLUSIONS

While none of the associations reached significance with Bonferroni correction, a common genetic variant near LPCAT1, a gene involved in the remodeling of phospholipids, was nominally associated with incident SCA risk. Further study is needed to validate this observation.

Accuracy of prehospital transport time estimation

OBJECTIVES

Estimates of prehospital transport times are an important part of emergency care system research and planning; however, the accuracy of these estimates is unknown. The authors examined the accuracy of three estimation methods against observed transport times in a large cohort of prehospital patient transports.

METHODS

This was a validation study using prehospital records in King County, Washington, and southwestern Pennsylvania from 2002 to 2006 and 2005 to 2011, respectively. Transport time estimates were generated using three methods: linear arc distance, Google Maps, and ArcGIS Network Analyst. Estimation error, defined as the absolute difference between observed and estimated transport time, was assessed, as well as the proportion of estimated times that were within specified error thresholds. Based on the primary results, a regression estimate was used that incorporated population density, time of day, and season to assess improved accuracy. Finally, hospital catchment areas were compared using each method with a fixed drive time.

RESULTS

The authors analyzed 29,935 prehospital transports to 44 hospitals. The mean (± standard deviation [±SD]) absolute error was 4.8 (±7.3) minutes using linear arc, 3.5 (±5.4) minutes using Google Maps, and 4.4 (±5.7) minutes using ArcGIS. All pairwise comparisons were statistically significant (p < 0.01). Estimation accuracy was lower for each method among transports more than 20 minutes (mean [±SD] absolute error was 12.7 [±11.7] minutes for linear arc, 9.8 [±10.5] minutes for Google Maps, and 11.6 [±10.9] minutes for ArcGIS). Estimates were within 5 minutes of observed transport time for 79% of linear arc estimates, 86.6% of Google Maps estimates, and 81.3% of ArcGIS estimates. The regression-based approach did not substantially improve estimation. There were large differences in hospital catchment areas estimated by each method.

CONCLUSIONS

Route-based transport time estimates demonstrate moderate accuracy. These methods can be valuable for informing a host of decisions related to the system organization and patient access to emergency medical care; however, they should be employed with sensitivity to their limitations.

Prehospital systolic blood pressure thresholds: a community-based outcomes study

OBJECTIVES

Emergency medical services (EMS) personnel commonly use systolic blood pressure (sBP) to triage and treat acutely ill patients. The definition of prehospital hypotension and its associated outcomes are poorly defined. The authors sought to determine the discrimination of prehospital sBP thresholds for 30-day mortality and to compare patient classification by best-performing thresholds to traditional cutoffs.

METHODS

In a community-based cohort of adult, nontrauma, noncardiac arrest patients transported by EMS between 2002 and 2006, entries to state hospital discharge data and death certificates were linked. Prehospital sBP thresholds between 40 and 140 mm Hg in derivation (n = 132,624) and validation (n = 22,020) cohorts and their discrimination for 30-day mortality, were examined. Cutoffs were evaluated using the 0/1 distance, Youden index, and adjusted Z-statistics from multivariable logistic regression models.

RESULTS

In the derivation cohort, 1,594 (1.2%) died within 24 hours, 7,404 (6%) were critically ill during hospitalization, and 6,888 (5%) died within 30 days. The area under the receiver operating characteristic (ROC) curve for sBP was 0.60 (95% confidence interval [CI] = 0.59, 0.61) for 30-day mortality and 0.64 (95% CI = 0.62 0.66) for 24-hour mortality. The 0/1 distance, Youden index, and adjusted Z-statistics found best-performing sBP thresholds between 110 and 120 mm Hg. When compared to an sBP ≤ 90 mm Hg, a cutoff of 110 mm Hg would identify 17% (n = 137) more deaths at 30 days, while overtriaging four times as many survivors.

CONCLUSIONS

Prehospital sBP is a modest discriminator of clinical outcomes, yet no threshold avoids substantial misclassification of 30-day mortality among noninjured patients.

Improving risk classification of critical illness with biomarkers: a simulation study

PURPOSE

Optimal triage of patients at risk for critical illness requires accurate risk prediction, yet few data on the performance criteria required of a potential biomarker to be clinically useful exists.

MATERIALS AND METHODS

We studied an adult cohort of nonarrest, nontrauma emergency medical services encounters transported to a hospital from 2002 to 2006. We simulated hypothetical biomarkers increasingly associated with critical illness during hospitalization and determined the biomarker strength and sample size necessary to improve risk classification beyond a best clinical model.

RESULTS

Of 57,647 encounters, 3121 (5.4%) were hospitalized with critical illness and 54,526 (94.6%) without critical illness. The addition of a moderate-strength biomarker (odds ratio, 3.0, for critical illness) to a clinical model improved discrimination (c statistic, 0.85 vs 0.8; P<.01) and reclassification (net reclassification improvement, 0.15; 95% confidence interval, 0.13-0.18) and increased the proportion of cases in the highest-risk category by +8.6% (95% confidence interval, 7.5%-10.8%). Introducing correlation between the biomarker and physiological variables in the clinical risk score did not modify the results. Statistically significant changes in net reclassification required a sample size of at least 1000 subjects.

CONCLUSIONS

Clinical models for triage of critical illness could be significantly improved by incorporating biomarkers, yet substantial sample sizes and biomarker strength may be required.

Severe sepsis in pre-hospital emergency care: analysis of incidence, care, and outcome

RATIONALE

Severe sepsis is common and highly morbid, yet the epidemiology of severe sepsis at the frontier of the health care system-pre-hospital emergency care-is unknown.

OBJECTIVES

We examined the epidemiology of pre-hospital severe sepsis among emergency medical services (EMS) encounters, relative to acute myocardial infarction and stroke.

METHODS

Retrospective study using a community-based cohort of all nonarrest, nontrauma King County EMS encounters from 2000 to 2009 who were transported to a hospital.

MEASUREMENTS AND MAIN RESULTS

Overall incidence rate of hospitalization with severe sepsis among EMS encounters, as well as pre-hospital characteristics, admission diagnosis, and outcomes. Among 407,176 EMS encounters, we identified 13,249 hospitalizations for severe sepsis, of whom 2,596 died in the hospital (19.6%). The crude incidence rate of severe sepsis was 3.3 per 100 EMS encounters, greater than for acute myocardial infarction or stroke (2.3 per 100 and 2.2 per 100 EMS encounters, respectively). More than 40% of all severe sepsis hospitalizations arrived at the emergency department after EMS transport, and 80% of cases were diagnosed on admission. Pre-hospital care intervals, on average, exceeded 45 minutes for those hospitalized with severe sepsis. One-half or fewer of patients with severe sepsis were transported by paramedics (n = 7,114; 54%) or received pre-hospital intravenous access (n = 4,842; 37%).

CONCLUSIONS

EMS personnel care for a substantial and increasing number of patients with severe sepsis, and spend considerable time on scene and during transport. Given the emphasis on rapid diagnosis and intervention for sepsis, the pre-hospital interval may represent an important opportunity for recognition and care of sepsis.

Long-term prognosis following resuscitation from out of hospital cardiac arrest: role of percutaneous coronary intervention and therapeutic hypothermia

OBJECTIVES

The aim of the study was to assess the influence of percutaneous coronary intervention (PCI) and therapeutic hypothermia (TH) on long-term prognosis.

BACKGROUND

Although hospital care consisting of TH and/or PCI in particular patients resuscitated following out-of-hospital cardiac arrest (OHCA) can improve survival to hospital discharge, there is little evidence regarding how these therapies may impact long-term prognosis.

METHODS

We performed a cohort investigation of all persons >18 years of age who suffered nontraumatic OHCA and were resuscitated and discharged alive from the hospital between January 1, 2001, and December 31, 2009, in a metropolitan emergency medical service (EMS) system. We reviewed EMS and hospital records, state death certificates, and the national death index to determine clinical characteristics and vital status. Survival analyses were conducted using Kaplan-Meier estimates and multivariable Cox regression. Analyses of TH were restricted to those patients who were comatose at hospital admission.

RESULTS

Of the 5,958 persons who received EMS-attempted resuscitation, 1,001 (16.8%) were discharged alive from the hospital. PCI was performed in 384 of 1,001 (38.4%), whereas TH was performed in 241 of 941 (25.6%) persons comatose at hospital admission. Five-year survival was 78.7% among those treated with PCI compared with 54.4% among those not receiving PCI and 77.5% among those treated with TH compared with 60.4% among those not receiving TH (both p < 0.001). After adjustment for confounders, PCI was associated with a lower risk of death (hazard ratio [HR]: 0.46 [95% confidence interval [CI]: 0.34 to 0.61]; p < 0.001). Likewise, TH was associated with a lower risk of death (HR: 0.70 [95% CI: 0.50 to 0.97]; p = 0.04).

CONCLUSIONS

The findings suggested that effects of acute hospital interventions for post-resuscitation treatment extend beyond hospital survival and can positively influence prognosis following the arrest hospitalization.

Major life events as potential triggers of sudden cardiac arrest

BACKGROUND

We investigated the risk of sudden cardiac arrest in association with the recent loss of, or separation from, a family member or friend.

METHODS

Our case-crossover study included 490 apparently healthy married residents of King County, Washington, who suffered sudden cardiac arrest between 1988 and 2005. We compared exposure to spouse-reported family/friend events occurring ≤ 1 month before sudden cardiac arrest with events occurring in the previous 5 months. We evaluated potential effect modification by habitual vigorous physical activity.

RESULTS

Recent family/friend events were associated with a higher risk of sudden cardiac arrest (odds ratio [OR] = 1.6; 95% confidence interval [CI] = 1.1-2.4). ORs for cases with and without habitual vigorous physical activity were 1.1 (0.6-2.2) and 2.0 (1.2-3.1), respectively (interaction P = 0.02).

CONCLUSIONS

These results suggest family/friend events may trigger sudden cardiac arrest and raise the hypothesis that habitual vigorous physical activity may lower susceptibility to these potential triggers.

Common variation in fatty acid genes and resuscitation from sudden cardiac arrest

BACKGROUND

Fatty acids provide energy and structural substrates for the heart and brain and may influence resuscitation from sudden cardiac arrest (SCA). We investigated whether genetic variation in fatty acid metabolism pathways was associated with SCA survival.

METHODS AND RESULTS

Subjects (mean age, 67 years; 80% male, white) were out-of-hospital SCA patients found in ventricular fibrillation in King County, WA. We compared subjects who survived to hospital admission (n=664) with those who did not (n=689), and subjects who survived to hospital discharge (n=334) with those who did not (n=1019). Associations between survival and genetic variants were assessed using logistic regression adjusting for age, sex, location, time to arrival of paramedics, whether the event was witnessed, and receipt of bystander cardiopulmonary resuscitation. Within-gene permutation tests were used to correct for multiple comparisons. Variants in 5 genes were significantly associated with SCA survival. After correction for multiple comparisons, single-nucleotide polymorphisms in ACSL1 and ACSL3 were significantly associated with survival to hospital admission. Single-nucleotide polymorphisms in ACSL3, AGPAT3, MLYCD, and SLC27A6 were significantly associated with survival to hospital discharge.

CONCLUSIONS

Our findings indicate that variants in genes important in fatty acid metabolism are associated with SCA survival in this population.

Increasing hospital volume is not associated with improved survival in out of hospital cardiac arrest of cardiac etiology

BACKGROUND

Resuscitation centers may improve patient outcomes by achieving sufficient experience in post-resuscitation care. We analyzed the relationship between survival and hospital volume among patients suffering out-of-hospital cardiac arrest (OHCA).

METHODS

This prospective cohort investigation collected data from the Cardiac Arrest Registry to Enhance Survival database from 10/1/05 to 12/31/09. Primary outcome was survival to discharge. Hospital characteristics were obtained via 2005 American Hospital Association Survey. A hospital's use of hypothermia was obtained via direct survey. To adjust for hospital- and patient-level variation, multilevel, hierarchical logistic regression was performed. Hospital volume was modeled as a categorical (OHCA/year≤10, 11-39, ≥40) variable. A stratified analysis evaluating those with ventricular fibrillation or pulseless ventricular tachycardia (VF/VT) was also performed.

RESULTS

The cohort included 4125 patients transported by EMS to 155 hospitals in 16 states. Overall survival to hospital discharge was 35% among those admitted to the hospital. Individual hospital rates of survival varied widely (0-100%). Unadjusted survival did not differ between the 3 hospital groups (36% for ≤10 OHCA/year, 35% for 11-39, and 36% for ≥40; p=0.75). After multilevel adjustment, differences in survival across the groups were not statistically significant. Compared to patients at hospitals with ≤10 OHCA/year, adjusted OR for survival was 1.04 (CI(95) 0.83-1.28) among 11-39 annual volume and 0.97 (CI(95) 0.73-1.30) among the ≥40 volume hospitals. Among patients presenting with VF/VT, no difference in survival was identified between the hospital groups.

CONCLUSION

Survival varied substantially across hospitals. However, hospital OHCA volume was not associated with likelihood of survival. Additional efforts are required to determine what hospital characteristics might account for the variability observed in OHCA hospital outcomes.

Socioeconomic indicators and the risk of acute coronary heart disease events: comparison of population-based data from the United States and Finland

PURPOSE

We wished to determine whether a gradient of association of low socioeconomic status with incidence of coronary heart disease was present in two population-based cohorts, one from United States and the other from Finland.

METHODS

Using data from the Atherosclerosis Risk in Communities (ARIC) cohort and the Finnish FINRISK cohort, we estimated, with Cox proportional hazard regression models, incidence of sudden cardiac death (SCD), non-sudden cardiac death (NSCD), and non-fatal myocardial infarction (NFMI) for strata of income and education (follow-up: 1987-2001). In both cohorts, incidence rates of the three outcomes increased across all socioeconomic status exposure categories.

RESULTS

Low education was associated with increased hazard of NFMI in both cohorts and with increased risk of SCD among ARIC women. Low income was significantly associated with increased hazard of all three outcomes among ARIC women and with increased hazard of cardiac death among ARIC men. In FINRISK, low income was significantly associated with increased risk of SCD only. Risk of SCD in the low income categories was similar for both cohorts. Smoking, alcohol consumption, and race (ARIC only) did not appreciably alter effect estimates in either cohort.

CONCLUSIONS

Indices of low SES show similar associations with increased risk of cardiac events in Finland and in United States.

Understanding of sepsis among emergency medical services: a survey study

BACKGROUND

Emergency medical services (EMS) personnel commonly encounter sepsis, yet little is known about their understanding of sepsis.

STUDY OBJECTIVES

To determine the awareness, knowledge, current practice, and attitudes about sepsis among EMS personnel.

METHODS

We performed an anonymous, multi-agency, online survey of emergency medical technicians (EMTs), firefighter-emergency medical technicians (FF-EMTs), and paramedics in a metropolitan, 2-tier EMS system. We compared responses according to the level of EMS training and used multivariable logistic regression to determine the odds of correctly identifying the definition of sepsis, independent of demographic and professional factors.

RESULTS

Overall response rate of study participants was 57% (786/1390), and was greatest among EMTs (79%; 276/350). A total of 761 respondents (97%) had heard of the term "sepsis." EMTs and FF-EMTs were at significantly reduced odds of correctly defining sepsis compared to paramedics, independent of age, sex, and years of experience (EMTs: odds ratio 0.44, 95% confidence interval 0.3-0.8; FF-EMTs: odds ratio 0.32, 95% confidence interval 0.2-0.6. Overall, knowledge of the clinical signs and symptoms and recommended treatments for sepsis was typically>75%, though better among paramedics than EMTs or FF-EMTs (p<0.01). The majority of respondents believed sepsis is not recognized by EMS "some" or "a lot" of the time (76%, 596/786).

CONCLUSIONS

EMS personnel demonstrated an overall sound awareness of sepsis. Knowledge of sepsis was less among FF-EMTs and EMTs compared to paramedics. These results suggest that paramedics could be integrated into strategies of early identification and treatment of sepsis, and EMTs may benefit from focused education and training.

Socioeconomic status and incidence of sudden cardiac arrest

BACKGROUND

Low socioeconomic status is associated with poor cardiovascular health. We evaluated the association between socioeconomic status and the incidence of sudden cardiac arrest, a condition that accounts for a substantial proportion of cardiovascular-related deaths, in seven large North American urban populations.

METHODS

Using a population-based registry, we collected data on out-of-hospital sudden cardiac arrests occurring at home or at a residential institution from Apr. 1, 2006, to Mar. 31, 2007. We limited the analysis to cardiac arrests in seven metropolitan areas in the United States (Dallas, Texas; Pittsburgh, Pennsylvania; Portland, Oregon; and Seattle-King County, Washington) and Canada (Ottawa and Toronto, Ontario; and Vancouver, British Columbia). Each incident was linked to a census tract; tracts were classified into quartiles of median household income.

RESULTS

A total of 9235 sudden cardiac arrests were included in the analysis. For all sites combined, the incidence of sudden cardiac arrestin the lowest socioeconomic quartile was nearly double that in the highest quartile (incidence rate ratio [IRR] 1.9, 95% confidence interval [CI] 1.8-2.0). This disparity was greater among people less than 65 years old (IRR 2.7, 95% CI 2.5-3.0) than among those 65 or older (IRR 1.3, 95% CI 1.2-1.4). After adjustment for study site and for population age structure of each census tract, the disparity across socioeconomic quartiles for all ages combined was greater in the United States (IRR 2.0, 95% CI 1.9-2.2) than in Canada (IRR 1.8, 95% CI 1.6-2.0) (p<0.001 for interaction).

INTERPRETATION

The incidence of sudden cardiac arrest at home or at a residential institution was higher in poorer neighbourhoods of the US and Canadian sites studied, although the association was attenuated in Canada. The disparity across socioeconomic quartiles was greatest among people younger than 65. The association between socioeconomic status and incidence of sudden cardiac arrest merits consideration in the development of strategies to improve survival from sudden cardiac arrest, and possibly to identify opportunities for prevention.

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.).

Early versus later rhythm analysis in patients with out-of-hospital cardiac arrest

BACKGROUND

In a departure from the previous strategy of immediate defibrillation, the 2005 resuscitation guidelines from the American Heart Association-International Liaison Committee on Resuscitation suggested that emergency medical service (EMS) personnel could provide 2 minutes of cardiopulmonary resuscitation (CPR) before the first analysis of cardiac rhythm. We compared the strategy of a brief period of CPR with early analysis of rhythm with the strategy of a longer period of CPR with delayed analysis of rhythm.

METHODS

We conducted a cluster-randomized trial involving adults with out-of-hospital cardiac arrest at 10 Resuscitation Outcomes Consortium sites in the United States and Canada. Patients in the early-analysis group were assigned to receive 30 to 60 seconds of EMS-administered CPR and those in the later-analysis group were assigned to receive 180 seconds of CPR, before the initial electrocardiographic analysis. The primary outcome was survival to hospital discharge with satisfactory functional status (a modified Rankin scale score of ≤3, on a scale of 0 to 6, with higher scores indicating greater disability).

RESULTS

We included 9933 patients, of whom 5290 were assigned to early analysis of cardiac rhythm and 4643 to later analysis. A total of 273 patients (5.9%) in the later-analysis group and 310 patients (5.9%) in the early-analysis group met the criteria for the primary outcome, with a cluster-adjusted difference of -0.2 percentage points (95% confidence interval, -1.1 to 0.7; P=0.59). Analyses of the data with adjustment for confounding factors, as well as subgroup analyses, also showed no survival benefit for either study group.

CONCLUSIONS

Among patients who had an out-of-hospital cardiac arrest, we found no difference in the outcomes with a brief period, as compared with a longer period, of EMS-administered CPR before the first analysis of cardiac rhythm. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.).

Intravenous access during out-of-hospital emergency care of noninjured patients: a population-based outcome study

STUDY OBJECTIVE

Advanced, out-of-hospital procedures such as intravenous access are commonly performed by emergency medical services (EMS) personnel, yet little evidence supports their use among noninjured patients. We evaluate the association between out-of-hospital, intravenous access and mortality among noninjured, non-cardiac arrest patients.

METHODS

We analyzed a population-based cohort of adult (aged ≥18 years) noninjured, non-cardiac arrest patients transported by 4 advanced life support agencies to one of 16 hospitals from January 1, 2002, until December 31, 2006. We linked eligible EMS records to hospital administrative data and used multivariable logistic regression to determine the risk-adjusted association between out-of-hospital intravenous access and hospital mortality. We also tested whether this association differed by patient acuity by using a previously published, out-of-hospital triage score.

RESULTS

Among 56,332 eligible patients, half (N=28,078; 50%) received out-of-hospital intravenous access from EMS personnel. Overall hospital mortality for patients who did and did not receive intravenous access was 3%. However, in multivariable analyses, the placement of out-of-hospital, intravenous access was associated with an overall reduction in odds of hospital mortality (odds ratio=0.68; 95% confidence interval [CI] 0.56 to 0.81). The beneficial association of intravenous access appeared to depend on patient acuity (P=.13 for interaction). For example, the odds ratio of mortality associated with intravenous access was 1.38 (95% CI 0.28 to 7.0) among patients with lowest acuity (score=0). In contrast, the odds ratio of mortality associated with intravenous access was 0.38 (95% CI 0.17 to 0.9) among patients with highest acuity (score ≥6).

CONCLUSION

In this population-based cohort, out-of-hospital efforts to establish intravenous access were associated with a reduction in hospital mortality among noninjured, non-cardiac arrest patients with the highest acuity. Reasons why this occurred (cause and effect) could not be determined in this model.

Reliability of the Cerebral Performance Category to classify neurological status among survivors of ventricular fibrillation arrest: a cohort study

Background

The Cerebral Performance Category (CPC) score is widely used in research and quality assurance to assess neurologic outcome following cardiac arrest. However, little is known about the inter- and intra-reviewer reliability of the CPC.

Methods

We undertook an investigation to assess the inter-reviewer and source document reliability of the CPC among a cohort of survivors from out-of-hospital ventricular fibrillation cardiac arrest (n = 131) in a large metropolitan area between November 1, 2003 and December 31, 2005. Subjects with a CPC of 1 or 2 were classified as favorable outcome and those with CPC 3 or greater were classified as unfavorable outcome. One abstractor first used the discharge summary alone to determine the CPC. All 3 abstractors independently reviewed the entire hospital record. Reliability was assessed by determining the proportion of determinations that agreed between abstractors and the respective kappa statistics. We also evaluated the implications for determining survival with favorable neurological outcome when survival to hospital discharge was 20% and 30%.

Results

When the entire hospital record was used to determine CPC, favorable neurologic outcome (CPC 1 or 2) was recorded in 92% by abstractor 1, 89% by abstractor 2, and 74% by abstractor 3. Agreement was 96% (kappa = 0.78) between abstractors 1 and 2, 84% (kappa = 0.49) between abstractors 2 and 3, 82% (kappa = 0.38) between abstractors 1 and 3. The 3-way kappa was 0.50. Agreement was 90% (kappa = 0.71) between the discharge summary alone and the entire hospital record. If the results from review of the entire record are applied to a circumstance where survival to discharge is 20%, favorable neurologic status would occur in 18.4% for abstractor 1, 17.8% for abstractor 2, and 14.8% for abstractor 3. For survival to hospital discharge of 30%, favorable neurologic status would occur in 27.6% for abstractor 1, 26.7% for abstractor 2, and 22.2% for abstractor 3.

Conclusions

In this cohort study of survivors of out-of-hospital ventricular fibrillation cardiac arrest, the use of the CPC to classify favorable versus unfavorable neurological status at hospital discharge produced variable inter- and intra-reviewer agreement. The findings provide useful context to interpret outcome evaluations that report CPC.