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Biomedical subjects

Leonard A Cobb

Publications and source records attributed to Leonard A Cobb.

13 recordsLinked to original sources
PubMed2006

Transthoracic incremental monophasic versus biphasic defibrillation by emergency responders (TIMBER): a randomized comparison of monophasic with biphasic waveform ascending energy defibrillation for the resuscitation of out-of-hospital cardiac arrest due to ventricular fibrillation.

BACKGROUND: Although biphasic, as compared with monophasic, waveform defibrillation for cardiac arrest is increasing in use and popularity, whether it is truly a more lifesaving waveform is unproven. METHODS AND RESULTS: Consecutive adults with nontraumatic out-of-hospital ventricular fibrillation cardiac arrest were randomly allocated to defibrillation according to the waveform from automated external defibrillators administered by prehospital medical providers. The primary event of interest was admission alive to the hospital. Secondary events included return of rhythm and circulation, survival, and neurological outcome. Providers were blinded to automated defibrillator waveform. Of 168 randomized patients, 80 (48%) and 68 (40%) consistently received only monophasic or biphasic waveform shocks, respectively, throughout resuscitation. The prevalence of ventricular fibrillation, asystole, or organized rhythms at 5, 10, or 20 seconds after each shock did not differ significantly between treatment groups. The proportion of patients admitted alive to the hospital was relatively high: 73% in monophasic and 76% in biphasic treatment groups (P=0.58). Several favorable trends were consistently associated with receipt of biphasic waveform shock, none of which reached statistical significance. Notably, 27 of 80 monophasic shock recipients (34%), compared with 28 of 68 biphasic shock recipients (41%), survived (P=0.35). Neurological outcome was similar in both treatment groups (P=0.4). Earlier administration of shock did not significantly alter the performance of one waveform relative to the other, nor did shock waveform predict any clinical outcome after multivariate adjustment. CONCLUSIONS: No statistically significant differences in outcome could be ascribed to use of one waveform over another when out-of-hospital ventricular fibrillation was treated.

Adult↗
PubMed2006

Manual chest compression vs use of an automated chest compression device during resuscitation following out-of-hospital cardiac arrest: a randomized trial.

CONTEXT: High-quality cardiopulmonary resuscitation (CPR) may improve both cardiac and brain resuscitation following cardiac arrest. Compared with manual chest compression, an automated load-distributing band (LDB) chest compression device produces greater blood flow to vital organs and may improve resuscitation outcomes. OBJECTIVE: To compare resuscitation outcomes following out-of-hospital cardiac arrest when an automated LDB-CPR device was added to standard emergency medical services (EMS) care with manual CPR. DESIGN, SETTING, AND PATIENTS: Multicenter, randomized trial of patients experiencing out-of-hospital cardiac arrest in the United States and Canada. The a priori primary population was patients with cardiac arrest that was presumed to be of cardiac origin and that had occurred prior to the arrival of EMS personnel. Initial study enrollment varied by site, ranging from late July to mid November 2004; all sites halted study enrollment on March 31, 2005. INTERVENTION: Standard EMS care for cardiac arrest with an LDB-CPR device (n = 554) or manual CPR (n = 517). MAIN OUTCOME MEASURES: The primary end point was survival to 4 hours after the 911 call. Secondary end points were survival to hospital discharge and neurological status among survivors. RESULTS: Following the first planned interim monitoring conducted by an independent data and safety monitoring board, study enrollment was terminated. No difference existed in the primary end point of survival to 4 hours between the manual CPR group and the LDB-CPR group overall (N = 1071; 29.5% vs 28.5%; P = .74) or among the primary study population (n = 767; 24.7% vs 26.4%, respectively; P = .62). However, among the primary population, survival to hospital discharge was 9.9% in the manual CPR group and 5.8% in the LDB-CPR group (P = .06, adjusted for covariates and clustering). A cerebral performance category of 1 or 2 at hospital discharge was recorded in 7.5% of patients in the manual CPR group and in 3.1% of the LDB-CPR group (P = .006). CONCLUSIONS: Use of an automated LDB-CPR device as implemented in this study was associated with worse neurological outcomes and a trend toward worse survival than manual CPR. Device design or implementation strategies require further evaluation. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00120965.

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PubMed2005

Pilot study of rapid infusion of 2 L of 4 degrees C normal saline for induction of mild hypothermia in hospitalized, comatose survivors of out-of-hospital cardiac arrest.

BACKGROUND: Recent clinical studies have demonstrated that mild hypothermia (32 degrees C to 34 degrees C) induced by surface cooling improves neurological outcome after resuscitation from out-of-hospital cardiac arrest. Results from animal models suggest that the effectiveness of mild hypothermia could be improved if initiated as soon as possible after return of spontaneous circulation. Infusion of cold, intravenous fluid has been proposed as a safe, effective, and inexpensive technique to induce mild hypothermia after cardiac arrest. METHODS AND RESULTS: In 17 hospitalized survivors of out-of-hospital cardiac arrest, we determined the effect on temperature and hemodynamics of infusing 2 L of 4 degrees C cold, normal saline during 20 to 30 minutes into a peripheral vein with a high-pressure bag. Data on vital signs, electrolytes, arterial blood gases, and coagulation were collected before and after fluid infusion. Cardiac function was assessed by transthoracic echocardiography before fluid administration and 1 hour after infusion. Passive (fans, leaving patient uncovered) or active (cooling blankets, neuromuscular blockade) cooling measures were used to maintain mild hypothermia for 24 hours. Infusion of 2 L of 4 degrees C cold, normal saline resulted in a mean temperature drop of 1.4 degrees C 30 minutes after the initiation of infusion. Rapid infusion of fluid was not associated with clinically important changes in vital signs, electrolytes, arterial blood gases, or coagulation parameters. The initial mean ejection fraction was 34%, and fluid infusion did not affect ejection fraction or increase central venous pressure, pulmonary pressures, or left atrial filling pressures as assessed by echocardiography. Passive measures were ineffective in maintaining hypothermia compared with active measures. CONCLUSIONS: Infusion of 2 L of 4 degrees C cold, normal saline is safe and effective in rapidly lowering body temperature in survivors of out-of-hospital cardiac arrest.

Adult↗
PubMed2005

Automated external defibrillators: to what extent does the algorithm delay CPR?

STUDY OBJECTIVE: Maximizing cardiopulmonary resuscitation (CPR) during resuscitation may improve survival. Resuscitation protocols stack up to 3 shocks to achieve defibrillation, followed by an immediate postdefibrillation pulse check. The purpose of this study is to evaluate outcomes of rhythm reanalyses immediately after shock, stacked shocks, and initial postshock pulse checks in relation to achieving a pulse and initiating CPR. METHODS: We conducted an observational study of patients with ventricular fibrillation treated by first-tier emergency medical services (EMS). We collected data from EMS, dispatch, and hospital records. Additionally, we analyzed automatic external defibrillator recordings to determine the proportion of cardiac arrest victims who were defibrillated and achieved a pulse according to shock number (single versus stacked shock), proportion of victims with a pulse during the initial postdefibrillation pulse check, and interval from initial shock to CPR. RESULTS: The study included 481 cardiac arrest subjects. Automatic external defibrillators terminated ventricular fibrillation with the initial shock in 83.6% (n=402) of cases. A second shock terminated ventricular fibrillation in an additional 7.5% (n=36) of cases, and a third shock terminated ventricular fibrillation in 4.8% (n=23) of cases. The initial sequence of 3 shocks failed to terminate ventricular fibrillation in 4.1% (n=20) of cases. In total, automatic external defibrillators performed 560 rhythm reanalyses during the initial shock sequence and delivered 122 "stacked" shocks. Termination of ventricular fibrillation was not synonymous with return of a pulse. The initial shock produced a pulse that was eventually detected in 21.8% (105/481) of cases. Stacked shocks produced a pulse in 10.7% (13/122) of cases. For the 24.5 % (n=118) of cases in which a pulse returned, the pulse was detected during the initial postshock pulse check only 12 times, or 2.5% of all cases. The median interval from initial shock until CPR was 29 (23,41) seconds. CONCLUSION: Rhythm reanalyses, stacked shocks, and postshock pulse checks had low yield for achieving or detecting return of a pulse. CPR was not initiated until 29 seconds after the initial shock.

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PubMed2004

Out-of-hospital care of critical drug overdoses involving cardiac arrest.

OBJECTIVES: Death from acute drug poisoning, also termed drug overdose, is a substantial public health problem. Little is known regarding the role of emergency medical services (EMS) in critical drug poisonings. This study investigates the involvement and potential mortality benefit of EMS for critical drug poisonings, characterized by cardiovascular collapse requiring cardiopulmonary resuscitation (CPR). METHODS: The study population was composed of death events caused by acute drug poisoning, defined as poisoning deaths and deaths averted (persons successfully resuscitated from out-of-hospital cardiac arrest by EMS) in King County, Washington, during the year 2000. RESULTS: Eleven persons were successfully resuscitated and 234 persons died from cardiac arrest caused by acute drug poisoning, for a total of 245 cardiac events. The EMS responded to 79.6% (195/245), attempted resuscitation in 34.7% (85/245), and successfully resuscitated 4.5% (11/245) of all events. Among the 85 persons for whom EMS attempted resuscitation, opioids, cocaine, and alcohol were the predominant drugs involved, although over half involved multiple drug classes. Among the 11 persons successfully resuscitated, return of circulation was achieved in six following EMS cardiopulmonary resuscitation alone, in one following CPR and defibrillation, and in the remaining four after additional advanced life support. CONCLUSIONS: In this community, EMS was involved in the majority of acute drug poisonings characterized by cardiovascular collapse and may potentially lower total mortality by approximately 4.5%. The results show that, in some survivors, return of spontaneous circulation may be achieved with CPR alone, suggesting a different pathophysiology in drug poisoning compared with cardiac arrest due to heart disease.

Adult↗
PubMed2003

Dispatcher assisted CPR: implementation and potential benefit. A 12-year study.

OBJECTIVES: Our objectives are to describe details of the dispatcher assisted cardiopulmonary resuscitation (CPR) instruction program we implemented during a 12 years study and to provide estimates of the potential number of out-of-hospital cardiac arrests that might benefit from such instruction based on data from the last 77 months. METHODS: Basic data were obtained for all episodes of out-of-hospital cardiac arrest in the city of Seattle, as well as all emergency medical services (EMS) dispatches for suspected cardiac arrest. In addition to EMS run reports, data sources included audio tapes of dispatches, and interviews of callers. These data were used in a potential benefit analysis. RESULTS: Over a period of 77 months, 54% (3320/6130) of cardiac arrests received advanced cardiac life support (ACLS) by Seattle Fire Department emergency medical technicians (EMTs) and paramedics. We estimated that 29.9% (994/3320) of cardiac arrests in Seattle treated by EMS could have theoretically benefited from dispatcher assisted CPR. No serious adverse consequences of a dispatcher assisted CPR program were observed. Failure to identify a cardiac arrest by dispatchers was largely attributed to deviation from a well-defined protocol. However, non-arrests identified, initially as arrests appeared to be unavoidable. CONCLUSIONS: In the city of Seattle, some 29.9% of all out-of-hospital cardiac arrest victims who received ACLS had the potential to benefit from dispatcher assisted CPR.

Cardiopulmonary Resuscitation↗
PubMed2003

Digoxin therapy and the risk of primary cardiac arrest in patients with congestive heart failure: effect of mild-moderate renal impairment.

BACKGROUND AND OBJECTIVE: The cardiac safety of digoxin therapy for congestive heart failure (CHF) is a source of concern, especially among those with renal impairment. METHODS: Using a case-control design, we examined the risk of primary cardiac arrest (PCA) associated with digoxin therapy within three levels of renal function. RESULTS: After adjustment for other clinical characteristics, digoxin therapy for CHF was not associated with an increased risk of PCA [odds ratio (OR)=0.97, 95% confidence interval (CI) 0.59-1.62] among patients with normal renal function (serum creatinine </=1.1 mg/dL). In contrast, digoxin therapy was associated with a modest increase in risk (OR=1.58, CI 0.89-2.80) among patients with mild renal impairment (serum creatinine=1.2-1.4 mg/dL); and a twofold increase in risk (OR=2.39, CI 1.37-4.18) among patients with moderate renal impairment (serum creatinine=1.5-3.5 mg/dL). CONCLUSIONS: These findings suggest that the risks of digoxin may offset the benefits among patients with moderately impaired renal function, but not among patients with normal renal function.

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PubMed2003

Emergency medical services and mortality from heart disease: a community study.

STUDY OBJECTIVES: Little is known regarding the potential effects of emergency medical services (EMS) on total heart disease mortality. Although EMS may provide health benefits in less acute cardiac conditions, its immediate, measurable, and direct effect on heart disease mortality is through resuscitation of persons suffering out-of-hospital cardiac arrest. The purpose of this study was to examine the involvement and potential mortality benefit of out-of-hospital EMS care of cardiac arrest on community heart disease mortality. METHODS: The investigation was an observational study of all persons with death events resulting from heart disease as defined by heart disease deaths and deaths averted (persons successfully resuscitated from out-of-hospital cardiac arrest by EMS) in a single county from January 1, 2000, through December 31, 2000. The county of study has a population of nearly 2 million people and is composed of urban, suburban, and rural components. State vital records and EMS reports were used to ascertain deaths resulting from heart disease and deaths averted. RESULTS: In the year 2000, 3,577 persons died as a result of heart disease, and 128 persons were successfully resuscitated and discharged from the hospital, for a total of 3,705 death events. EMS responded to 39% (1,428/3,705) of all heart disease death events and 57% (1,428/2,516) of out-of-hospital events, resulting in a 3.5% (128/3,705) reduction in overall heart disease mortality and a 5.1% (128/2,516) reduction in out-of-hospital mortality. CONCLUSION: EMS was involved in the majority of out-of-hospital heart disease death events, resulting in a measurable reduction in heart disease mortality.

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PubMed2002

Changing incidence of out-of-hospital ventricular fibrillation, 1980-2000.

CONTEXT: Recent reports from 2 European cities and an earlier observation from Seattle, Wash, suggest that the number of patients treated for out-of-hospital ventricular fibrillation (VF) has declined. OBJECTIVE: To analyze the incidence of cardiac arrest and to examine relationships among incidence, sex, race, age, and first identified cardiac rhythm in Seattle. DESIGN, SETTING, AND PATIENTS: Population-based study of all cardiac arrest cases with presumed cardiac etiology who received advanced life support from Seattle Fire Department emergency medical services during specified periods between 1979 and 2000. United States Census data for Seattle in 1980, 1990, and 2000 were used to determine incidence rates for treated cardiac arrest with adjustments for age and sex. MAIN OUTCOME MEASURES: Changes in incidence of cardiac arrest and initial recorded cardiac rhythm. RESULTS: The adjusted annual incidence of cardiac arrest with VF as the first identified rhythm decreased by about 56% from 1980 to 2000 (from 0.85 to 0.38 per 1000; relative risk [RR], 0.44; 95% confidence interval [CI], 0.37-0.53). Similar reductions occurred in blacks (54%; RR, 0.45; 95% CI, 0.26-0.79) and whites (53%; RR, 0.47; 95% CI, 0.38-0.58) and was most evident in men (57%; RR, 0.43; 95% CI, 0.35-0.53), in whom the baseline incidence was relatively high. When all treated arrests with presumed cardiac etiology were considered, that incidence decreased by 43% (RR, 0.58; 95% CI, 0.49-0.67) in men but negligibly in women, for whom a relatively low incidence of VF also declined but was offset by more cases with asystole or pulseless electrical activity. CONCLUSION: We observed a major decline in the incidence of out-of-hospital VF and in all cases of treated cardiac arrest presumably due to heart disease in Seattle. These changes likely reflect the national decline in coronary heart disease mortality.

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PubMed2002

Cell membrane trans-fatty acids and the risk of primary cardiac arrest.

BACKGROUND: The relation of trans-fatty acid intake to life-threatening arrhythmias and primary cardiac arrest is unknown. METHODS AND RESULTS: We investigated the association of trans-fatty acid intake, assessed through a biomarker, with the risk of primary cardiac arrest in a population-based case-control study. Cases, aged 25 to 74 years, were out-of-hospital cardiac arrest patients attended by paramedics in Seattle, Washington from 1988 to 1999 (n=179). Controls, matched to cases by age and sex, were randomly identified from the community (n=285). Participants were free of previous clinically diagnosed heart disease. Blood was obtained at the time of cardiac arrest (cases) or at the time of an interview (controls) to assess trans-fatty acid intake. Higher total trans-fatty acids in red blood cell membranes was associated with a modest increase in the risk of primary cardiac arrest after adjustment for medical and lifestyle risk factors (odds ratio for interquintile range, 1.5; 95% CI, 1.0 to 2.1). However, trans isomers of oleic acid were not associated with risk (odds ratio for interquintile range, 0.8; 95% CI, 0.5 to 1.2), whereas higher levels of trans isomers of linoleic acid were associated with 3-fold increase in risk (odds ratio for interquintile range, 3.1; 95% CI, 1.7 to 5.4). CONCLUSIONS: These findings suggest that dietary intake of total trans-fatty acids is associated with modest increase and trans isomers of linoleic acid with a larger increase in the risk of primary cardiac arrest. These associations need to be confirmed in future studies that distinguish between trans isomers of linoleic acid and trans isomers of oleic acid.

Adult↗
PubMed2002

Sudden death and myocardial infarction in first degree relatives as predictors of primary cardiac arrest.

The hypothesis that family history (FH) of myocardial infarction (MI) and FH of sudden death (SD) are both independent risk factors for primary cardiac arrest (PCA) was examined in a case-control study. PCA cases were attended by paramedics (1988-1994) and community-based age and sex matched controls were identified. Subjects (25-74 years) were free of prior clinically-recognized heart disease and major co-morbidity. Interviewers obtained a detailed history of MI and SD in first-degree relatives from spouses of 235 cases and 374 control subjects. A parental history of early-onset SD (age <65) was associated with an increased risk of PCA (odds ratio (OR)=2.69, 95% CI=1.35-5.36), after adjustment for parental history of MI and other risk factors. A parental history of late-onset SD was not associated with PCA risk (OR=0.94, 95% CI=0.55-1.62). Additionally, parental history of SD was related to early-onset PCA (OR=1.89, 95% CI=1.08-3.30) but not to late-onset PCA (OR=0.89, 95% CI=0.49-1.61). In contrast, parental MI (early/late) was related to PCA (early/late), after adjustment for other risk factors and parental history of SD. Similar results were observed in first-degree relatives. Findings suggest a potential role of familial factors related to both MI and SD in PCA. Stronger findings for a familial patterning of PCA were noted for early onset disease in cases and their relatives.

Adult↗