The dispatcher assisted resuscitation trial: indirect benefits of emergency research.

OBJECTIVE: Conduct of emergency research under waiver of consent produces special challenges. Moreover, the act of performing research may have unintended effects, potentially beneficial or detrimental. The Dispatcher-Assisted Randomized Trial (DART) was designed to compare 2 types of dispatcher cardiopulmonary (CPR) instruction, but not intended to affect the proportion of arrest victims that received bystander CPR. We sought to determine whether odds of receiving bystander CPR were higher during DART than during the periods before and after. METHODS: We conducted an observational cohort study of 8626 adults who suffered non-traumatic out-of-hospital cardiac arrest prior to emergency medical services (EMS) arrival in greater King County, Washington, between January 1, 1999, and December 31, 2011. Bystander CPR status was assessed through review of dispatch recordings and EMS reports to classify any bystander CPR (any B-CPR), and further categorized as bystander CPR with or without dispatcher assistance (DA-CPR and B-CPR, no DA). We used multivariable logistic regression to evaluate odds of B-CPR before, during, and after DART. RESULTS: The proportions receiving any B-CPR were 52% before DART (1817/3468), 59% during DART (2093/3527), and 54% after DART (885/1631). Compared to the period before DART, odds of receiving any B-CPR were higher during DART (OR=1.35, 95% CI=1.23-1.49), but no different after (OR=1.10, 0.98-1.24). Compared to the before period, odds of DA-CPR were higher during DART (OR=1.79, 1.59-2.02) but no different after (OR=0.94, 0.80-1.10). CONCLUSIONS: Odds of bystander CPR were higher during the trial, an increase related to higher likelihood of DA-CPR. The finding suggests a possible indirect community-wide benefit due to the interventional trial.

Predicting non-cardiac aetiology: a strategy to allocate rescue breathing during bystander CPR.

AIMS: Optimal care for out-of hospital cardiac arrest (OHCA) patients may depend on the underlying aetiology of OHCA. Specifically chest compression only bystander CPR may provide greater benefit among those with cardiac aetiology and chest compressions plus rescue breathing may provide greater benefit among those with non-cardiac aetiology. The aim of this study was to generate a simple predictor model to identify OHCA patients with non-cardiac aetiology in order to accurately allocate rescue breathing. METHODS: We used two independent cohorts of OHCA patients from a randomized pre-hospital trial and a prospective hospital registry (total n=3086) to assess whether the characteristics of age, gender and arrest location (private versus public) could sufficiently discriminate non-cardiac aetiology. We used logistic regression models to generate a receiver operator curve and likelihood ratios. RESULTS: Overall, 965/3086 (31%) had a final diagnosis of a non-cardiac cause. Using 8 exclusive groups according to age, gender, and location, the frequency of non-cardiac aetiology varied from a low of 16% (55/351) among men >age 50 in a public location up to 58% (199/346) among women <60 in a private location. Although each characteristic was predictive in the logistic regression model, the area under the curve in the receiver operating curve was only 0.66. The associated positive likelihood ratios ranged from 1 to 3 and the negative likelihood ratios ranged from 1 to 0.4. CONCLUSION: The results highlight the challenge of accurately identifying non-cardiac aetiology by characteristics that could be consistently used to allocate bystander rescue breathing.

Outcome of cardiac arrests attended by emergency medical services staff at community outpatient dialysis centers.

Cardiac arrest is the leading cause of death among dialysis patients in the United States. We measured the outcome of cardiac arrests attended by Emergency Medical Services (EMS) staff at hemodialysis facilities in a 14-year population-based retrospective study to identify cardiac arrest cases at a dialysis unit. Associated factors were determined using unconditional logistic regression. Of the 102 cardiac arrests identified around the time of dialysis, 10 occurred before, 72 during, and 20 after hemodialysis. The initial measured abnormality was ventricular fibrillation or tachycardia in 72 cases. Of those who survived transportation to a hospital, survival to discharge was 24 with 15% survival at 1 year. Compared to arrests that occurred prior to dialysis, the odds of ventricular fibrillation were 5-fold greater in patients on dialysis but 14-fold greater in those arresting after dialysis. One-third of cases occurred after the introduction of automated external defibrillators, and in half of the cases these devices were attached prior to EMS arrival. Once these devices were attached, most were used for defibrillation. We conclude that ventricular arrhythmias are the predominant features among arrested in-center dialysis patients with most occurrences during dialysis. The role of these devices in dialysis units will need a larger study to evaluate their efficacy.

NSAID use and dementia risk in the Cardiovascular Health Study: role of APOE and NSAID type.

BACKGROUND: Epidemiologic and laboratory studies suggest that nonsteroidal antiinflammatory drugs (NSAIDs) reduce risk of Alzheimer disease (AD). We therefore investigated the association between use of NSAIDs, aspirin, and the non-NSAID analgesic acetaminophen with incidence of dementia and AD. METHODS: Participants in the Cardiovascular Health Cognition Study included 3,229 individuals aged 65 or older, free of dementia at baseline, with information on medication use. We used Cox proportional hazards regression to estimate the association of medication use with incident all-cause dementia, AD, and vascular dementia (VaD). Additional analyses considered the NSAID-AD relationship as a function of age, presence of at least one epsilon 4 allele at APOE, race, and individual NSAIDs' reported ability to reduce production of the amyloid-beta peptide variant A beta(42). RESULTS: Use of NSAIDs was associated with a lower risk of dementia (adjusted hazard ratio or aHR 0.76, 95% CI or CI 0.60-0.96) and, in particular, AD (aHR 0.63, CI 0.45-0.88), but not VaD (aHR 0.92, CI 0.65-1.28). No similar trends were observed with acetaminophen (aHR 0.99, CI 0.79-1.24). Closer examination suggested AD risk reduction with NSAIDs only in participants having an APOE epsilon 4 allele (aHR 0.34, CI 0.18-0.65; aHR for others 0.88, CI 0.59-1.32). There was no advantage in AD risk reduction with NSAIDs reported to selectively reduce A beta(42). CONCLUSIONS: Results were consistent with previous cohort studies showing reduced risk of AD in NSAID users, but this association was found only in those with an APOE epsilon 4 allele, and there was no advantage for A beta(42)-lowering NSAIDs.

Respiratory muscle strength and the risk of incident cardiovascular events.

BACKGROUND: Maximal inspiratory pressure (MIP) is a measure of inspiratory muscle strength. The prognostic importance of MIP for cardiovascular events among elderly community dwelling individuals is unknown. Diminished forced vital capacity (FVC) is a risk factor for cardiovascular events which remains largely unexplained. METHODS: MIP was measured at the baseline examination of the Cardiovascular Health Study. Participants had to be free of prevalent congestive heart failure (CHF), myocardial infarction (MI), and stroke. RESULTS: Subjects in the lowest quintile of MIP had a 1.5-fold increased risk of MI (HR 1.48, 95% CI 1.07 to 2.06) and cardiovascular disease (CVD) death (HR 1.54, 95% CI 1.09 to 2.15) after adjustment for non-pulmonary function covariates. There was a potential inverse relationship with stroke (HR 1.36, 95% CI 0.97 to 1.90), but there was little evidence of an association between MIP and CHF (HR 1.22, 95% CI 0.93 to 1.60). The addition of FVC to models attenuated the HR associated with MIP only modestly; similarly, addition of MIP attenuated the HR associated with FVC only modestly. CONCLUSIONS: A reduced MIP is an independent risk factor for MI and CVD death, and a suggestion of an increased risk for stroke. This association with MIP appeared to be mediated through mechanisms other than inflammation.

Dispatcher-assisted cardiopulmonary resuscitation and survival in cardiac arrest.

BACKGROUND: Early cardiopulmonary resuscitation (CPR) improves survival in out-of-hospital cardiac arrest, and dispatcher-delivered instruction in CPR can increase the proportion of arrest victims who receive bystander CPR before emergency medical service (EMS) arrival. However, little is known about the survival effectiveness of dispatcher-delivered telephone CPR instruction. METHODS AND RESULTS: We evaluated a population-based cohort of EMS-attended adult cardiac arrests (n=7265) from 1983 through 2000 in King County, Washington, to assess the association between survival to hospital discharge and 3 distinct CPR groups: no bystander CPR before EMS arrival (no bystander CPR), bystander CPR before EMS arrival requiring dispatcher instruction (dispatcher-assisted bystander CPR), and bystander CPR before EMS arrival not requiring dispatcher instruction (bystander CPR without dispatcher assistance). In this cohort, 44.1% received no bystander CPR before EMS arrival, 25.7% received dispatcher-assisted bystander CPR, and 30.2% received bystander CPR without dispatcher assistance. Overall survival was 15.3%. Using no bystander CPR as the reference group, the multivariate adjusted odds ratio of survival was 1.45 (95% confidence interval [CI], 1.21, 1.73) for dispatcher-assisted bystander CPR and 1.69 (95% CI, 1.42, 2.01) for bystander CPR without dispatcher assistance. CONCLUSION: Dispatcher-assisted bystander CPR seems to increase survival in cardiac arrest.

Dispatcher assistance and automated external defibrillator performance among elders.

OBJECTIVES: Automated external defibrillators (AEDs) provide an opportunity to improve survival in out-of-hospital, ventricular fibrillation (VF) cardiac arrest by enabling laypersons not trained in rhythm recognition to deliver lifesaving therapy. The potential role of emergency dispatchers in the layperson use of AEDs is uncertain. This study was performed to examine whether dispatcher telephone assistance affected AED skill performance during a simulated VF cardiac arrest among a cohort of older adults. The hypothesis was that dispatcher assistance would increase the proportion who were able to correctly deliver a shock, but might require additional time. METHODS: One hundred fifty community-dwelling persons aged 58-84 years were recruited from eight senior centers in King County, Washington. All participants had received AED training approximately six months previously. For this study, the participants were randomized to AED operation with or without dispatcher assistance during a simulated VF cardiac arrest. The proportions who successfully delivered a shock and the time intervals from collapse to shock were compared between the two groups. RESULTS: The participants who received dispatcher assistance were more likely to correctly deliver a shock with the AED during the simulated VF cardiac arrest (91% vs 68%, p = 0.001). Among those who were able to deliver a shock, the participants who received dispatcher assistance required a longer time interval from collapse to shock [median (25th, 75th percentile) = 193 seconds (165, 225) for dispatcher assistance, and 148 seconds (138, 166) for no dispatcher assistance, p = 0.001]. CONCLUSIONS: Among older laypersons previously trained in AED operation, dispatcher assistance may increase the proportion who can successfully deliver a shock during a VF cardiac arrest.

Body mass index and the risk of recurrent coronary events following acute myocardial infarction.

Although excess adiposity appears to increase the risk of coronary heart disease in the general population, its importance in patients with established coronary disease is less defined. We evaluated a population-based inception cohort of survivors to hospital discharge following first acute myocardial infarction (AMI) (n = 2,541) to assess the association between body mass index (BMI) and the risk of recurrent coronary events and to explore the mechanisms for this relation. Using Cox proportional-hazards regression, we assessed the risk of recurrent coronary events associated with levels of adiposity as defined by BMI and then investigated potential mechanisms through which adiposity conferred risk by examining how adjustment for diabetes mellitus, systemic hypertension, and dyslipidemia affected the association. Forty-one percent of the cohort were overweight (BMI 25 to 29.9), and 27.8% were obese (BMI > or =30). After adjustment for other risk factors, the risk of recurrent coronary events (n = 418) increased as BMI increased, especially among those who were obese. Using a BMI of 16 to 24.9 as the reference group, for mildly overweight patients (BMI 25 to 27.4), the relative risk (RR) was 0.93 (95% confidence interval [CI] 0.70 to 1.24); it was 1.16 for more severe overweight patients (BMI 27.5 to 29.9; 95% CI 0.87 to 1.55). For patients with class I obesity (BMI 30 to 34.9), the RR was 1.49 (95% CI 1.12 to 1.98), and for class II to III obesity (BMI > or =35), the RR was 1.80 (95% CI 1.30 to 2.48). We estimated that clinical measurements of diabetes, hypertension, and dyslipidemia explained approximately 43% of this risk. Thus, excess adiposity as measured by BMI was associated with an increased risk of recurrent coronary events following AMI, particularly among those who were obese.

Prospective study of the natural history of infectious mononucleosis caused by Epstein-Barr virus.

BACKGROUND: Knowledge regarding the clinical characteristics and natural history of acute infectious mononucleosis is based largely on older, often retrospective, studies without systematic follow-up. Differences in diagnosis, methodology, or treatment between historical and current practice might affect an understanding of this illness. METHODS: Using a prospective case series design, we enrolled 150 persons with an acute illness serologically confirmed as Epstein-Barr virus infection. The goal of the study was to assess symptoms, physical examination findings, laboratory tests, and functional status measures during the acute presentation and 1, 2, and 6 months later. RESULTS: Acutely, infectious mononucleosis was characterized by the symptoms of sore throat and fatigue and substantial functional impairment. Objective physical and laboratory examination findings included pharyngitis and cervical lymphadenopathy, a moderate absolute and atypical lymphocytosis, and mildly elevated transaminase levels. The traditional signs of fever and splenomegaly were relatively uncommon. By 1 month, most symptoms and signs and all laboratory tests had returned to normal. Fatigue, cervical lymphadenopathy, pharyngitis, and functional health status improved more slowly. CONCLUSIONS: In contemporary practice most of the classical illness features of infectious mononucleosis are observed. Symptoms, signs, and poor functioning might be protracted in some patients.

Acute infectious mononucleosis: characteristics of patients who report failure to recover.

PURPOSE: We sought to determine how often acute mononucleosis precipitates chronic illness, and to describe the demographic, clinical, and psychosocial features that characterize patients who report failure to recover. SUBJECTS AND METHODS: We enrolled 150 patients with infectious mononucleosis during the acute illness and asked them to assess their recovery at 2 and 6 months. At baseline, we performed physical and laboratory examinations; obtained measures of psychological and somatic functioning, social support, and life events; and administered a structured psychiatric interview. RESULTS: Self-assessed failure to recover was reported by 38% of patients (55 of 144) at 2 months and by 12% (17 of 142) at 6 months. Those who had not recovered reported a persistent illness characterized by fatigue and poor functional status. No objective measures of disease, including physical examination findings or serologic or laboratory markers, distinguished patients who failed to recover from those who reported recovery. Baseline predictors for failure to recover at 2 months were older age (odds ratio [OR] = 1.4, 95% confidence interval [CI]: 1.1 to 1.8, per 5-year increase), higher temperature (OR = 1.5, 95% CI: 1.1 to 2.2, per 0.5 degrees C increase), and greater role limitation due to physical functioning (OR = 1.5, 95% CI: 1.2 to 1.9, per 20-point decrease in Short Form-36 score). At 6 months, baseline predictors for failure to recover included female sex (OR = 3.3, 95% CI: 1.0 to 12), a greater number of life events more than 6 months before the disease began (OR = 1.7, 95% CI: 1.1 to 2.5, per each additional life event), and greater family support (OR = 1.9, 95% CI: 1.1 to 4.2, per 7-point increase in social support score). CONCLUSIONS: We were not able to identify objective measures that characterized self-reported failure to recover from acute infectious mononucleosis. The baseline factors associated with self-reported failure to recover at 2 months differed from those associated with failure to recover at 6 months. Future studies should assess the generalizability of these findings and determine whether interventions can hasten recovery.