Biomedical subjects

Michael K Copass

Publications and source records attributed to Michael K Copass.

14 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↗

PubMed2005

Salmonella inhibit T cell proliferation by a direct, contact-dependent immunosuppressive effect.

Dendritic cells (DC) are of central importance in the initiation of T cell-mediated adaptive immunity because these professional phagocytes internalize, process, and present microbial antigens to T lymphocytes. T lymphocytes have a pivotal role in controlling and clearing infection with intracellular pathogens through cytokine production. T lymphocytes also can mediate direct lysis of infected cells or activate B and T cells. In this article, we report that DC, when cocultured with Salmonella, fail to efficiently stimulate T cells for proliferation. We show that the failure of T lymphocytes to respond to Salmonella-infected DC is not simply due to Salmonella-induced programmed DC death or interference with up-regulation of costimulatory molecules CD80 and CD86. We cocultured bacteria with purified T lymphocytes, and we demonstrate here that Salmonella have a direct, contact-dependent inhibitory effect on the T cells, even in the absence of DC. This direct, Salmonella-induced inhibitory effect reduces the ability of T cells to proliferate and produce cytokines in response to stimulation and appears to require live bacteria. Cumulatively, these results are evidence that Salmonella may interfere with the development of acquired immunity, providing insights into the complex nature of this host-pathogen interaction.

Animals↗

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.

Aged↗

PubMed2005

The use of neuromuscular blocking agents to facilitate prehospital intubation does not impair outcome after traumatic brain injury.

BACKGROUND: Several studies have demonstrated that the success rate of prehospital intubation is improved by the use of neuromuscular blocking agents (NMBAs). However, a recent study has reported that prehospital intubation with NMBAs worsens outcome after traumatic brain injury (TBI). We sought to determine the effect of the use of NMBAs to facilitate prehospital intubation on outcome after TBI. METHODS: All patients admitted to our Level I trauma center with a head Abbreviated Injury Scale score >/= 3 were identified by the trauma registry (January 1998-June 2003). Patient records were matched with prehospital databases. Patients were further stratified on the basis of prehospital Glasgow Coma Scale (GCS) score into mild (GCS score of 14/15), moderate (GCS score of 9-13), and severe (GCS score < 9) TBI. Outcome included mortality and good outcome (survival to discharge with a GCS score of 14/15). RESULTS: There were 3,052 patients who were identified as having been transported directly from the field. Complete prehospital data were available for 2,012 patients (66%). Of these, 920 were mild TBI (intubation rate, 17.4%), 293 moderate TBI (intubation rate, 57.7%), and 799 severe TBI (intubation rate, 95%). Overall, 72% of intubated patients received NMBAs. There were no significant differences in demographics or injury severity between the groups. Patients not receiving NMBAs were more likely to be hypotensive and have prehospital cardiopulmonary resuscitation (p = 0.001). The unadjusted mortality for the patients intubated with NMBAs was 25% versus 37% for those not receiving NMBAs (p < 0.001). When adjusted for confounding variables, patients intubated with NMBAs were more likely to survive (odds ratio, 0.63; 95% confidence interval, 0.41-0.97; p = 0.04) and have a good outcome (odds ratio, 1.7; 95% confidence interval, 1.2-2.6; p = 0.006) than those in the no-NMBA group. CONCLUSION: The use of NMBAs to facilitate prehospital intubation improves outcome for patients with TBI. The value of prehospital intubation for TBI remains to be determined; however, any trial evaluating nonintubation for TBI must be compared with NMBA-facilitated intubation to be valid.

Abbreviated Injury Scale↗

PubMed2005

Trauma patients receiving CPR: predictors of survival.

OBJECTIVE: To determine whether prehospital clinical assessments are associated with the survival of traumatic cardiopulmonary arrest (TCPA) patients and to test recently issued clinical guidelines for prehospital cessation of resuscitative efforts published by the National Association of Emergency Physicians and the American College of Surgeons Committee on Trauma. METHODS: A retrospective cohort study was done of all TCPA patients who had transported to a Level I trauma center by a municipal EMS provider between January 1, 1994 and April 1, 2001. Data regarding mechanism of injury, clinical assessments and care provided by EMS and the emergency department (ED), hospital care, survival, and neurologic outcome was collected. RESULTS: 184 patients met exclusion criteria, with 14 (7.6%) surviving to discharge. Pupillary response to light, presence of a prehospital pulse or respiratory effort, a sinus electrocardiogram, and a Glascow Coma Scale greater than three were all significantly associated with survival but were not exclusive. 28.6% of patients admitted to the trauma center from the ED survived. There were frequent discrepancies between prehospital and ED clinical assessments. Several survivors met criteria for non-treatment according to the proposed clinical guidelines. CONCLUSIONS: +/- Prehospital clinical assessments are not reliable for the triage of TCPA patients. Patients should be transported to the ED for further evaluation and care. The guidelines should not adopted until more thorough studies are conducted.

Adolescent↗

PubMed2004

Public access defibrillation in out-of-hospital cardiac arrest: a community-based study.

BACKGROUND: The dissemination and use of automated external defibrillators (AEDs) beyond traditional emergency medical services (EMS) into the community has not been fully evaluated. We evaluated the frequency and outcome of non-EMS AED use in a community experience. METHODS AND RESULTS: The investigation was a cohort study of out-of-hospital cardiac arrest cases due to underlying heart disease treated by public access defibrillation (PAD) between January 1, 1999, and December 31, 2002, in Seattle and surrounding King County, Washington. Public access defibrillation was defined as out-of-hospital cardiac arrest treated with AED application by persons outside traditional emergency medical services. The EMS of Seattle and King County developed a voluntary Community Responder AED Program and registry of PAD AEDs. During the 4 years, 475 AEDs were placed in a variety of settings, and more than 4000 persons were trained in cardiopulmonary resuscitation and AED operation. A total of 50 cases of out-of-hospital cardiac arrest were treated by PAD before EMS arrival, which represented 1.33% (50/3754) of all EMS-treated cardiac arrests. The proportion treated by PAD AED increased each year, from 0.82% in 1999 to 1.12% in 2000, 1.41% in 2001, and 2.05% in 2002 (P=0.019, test for trend). Half of the 50 persons treated with PAD survived to hospital discharge, with similar survival for nonmedical settings (45% [14/31]) and out-of-hospital medical settings (58% [11/19]). CONCLUSIONS: PAD was involved in only a small but increasing proportion of out-of-hospital cardiac arrests.

Aged↗

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

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.

Aged↗

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.

Aged↗

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

An analysis of advanced prehospital airway management.

Considerable controversy persists regarding the optimal means and indications for airway management, the utility of paralytic agents to facilitate intubation, and the indications for advanced airway access techniques in the prehospital setting. To describe the use of intubation and advanced airway management in a system with extensive experience with both the use of paralytic agents and surgical airway techniques, a retrospective review was conducted of all prehospital airway procedures from January 1997 through November 1999. Data collected included demographics, airway management techniques, use of paralytic agents, and immediate outcome. The results showed there were 2700 patients intubated out of 50,118 patient encounters (5.4%). The indications for intubation included medical emergency in 82% of patients and traumatic injury in 18%. Fifty percent of patients were intubated with the use of succinylcholine. The overall oral intubation success rate was 98.4% and definitive airway access was achieved in all but 12 patients (0.6%), with 30 patients receiving surgical airway access (1%). The successful intubation rate for patients receiving paralytic agents was 97.8%. Previously published rates of prehospital surgical airway access range from 3.8 to 14.9% of patients. In this study, only 1.1% of patients required a surgical airway. We attribute this low rate to the use of paralytic agents. The availability of paralytic agents also allows expansion of the indications for prehospital airway control.

Adolescent↗

PubMed2002

Behavior change counseling in the emergency department to reduce injury risk: a randomized, controlled trial.

OBJECTIVE: To determine whether a brief session of behavior change counseling (BCC), offered to injured adolescents in the emergency department (ED) as a therapeutic intervention, could be used to change injury-related risk behaviors and the risk of reinjury. STUDY DESIGN: A randomized, controlled trial. PARTICIPANTS: Adolescents between 12 and 20 years old who were undergoing treatment for an injury in the ED and who were cognitively able to participate in the intervention. SETTING: An urban ED at a level 1 pediatric trauma center. INTERVENTION: Study participants completed a baseline risk behavior prevalence assessment. Participants were then randomly assigned to receive BCC or routine ED care. Those in the treatment group underwent a brief session of BCC with a study social worker focused on changing an identified injury-related risk behavior (seatbelt use, bicycle helmet use, driving after drinking, riding with an impaired driver, binge drinking, or carrying a weapon). Participants were recontacted 3 months and 6 months after enrollment to assess the prevalence of positive behavior change and the interim occurrence of medically treated injuries. RESULTS: We enrolled 631 participants (78% of those eligible) and obtained follow-up for 76% at 3 months and 75% at 6 months. The relative risk of a positive behavior change with respect to seatbelt use was 1.34 (95% confidence interval [CI]: 1.00, 1.79) at 3 months, favoring the intervention group. The relative risk for the same outcome was 1.47 (95% CI: 1.09, 1.96) at 6 months. A positive change in bicycle helmet use was 1.81 (95% CI: 1.02, 3.18) times more likely at 3 months and 2.00 (95% CI: 1.00, 4.00) times more likely at 6 months in the intervention group. There was no effect of the intervention on changes in other target behaviors. Over the 6-month follow-up period, the risk of reinjury requiring medical attention did not differ between treatment groups. CONCLUSIONS: Brief BCC can be delivered to adolescents undergoing treatment for injury in the ED and can be used to address injury-related risk behaviors. The intervention was associated with a greater likelihood of positive behavior change in seatbelt and bicycle helmet use. This effect lasted over 6 months of follow-up. BCC was not associated with changes in other risk behaviors and could not be shown to significantly reduce the risk of reinjury.

Accident Prevention↗