Annals of emergency medicine
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To add to our understanding of survival rates in out-of-hospital cardiac arrest studies, we examined the incidence of cardiac arrest in the published literature. We specifically estimated if incidence rates are uniform between communities and if any relationship exists between incidence and the reported survival rates. ⋯ The marked variations in incidence and inverse relationship between incidence and survival could be due to true variation in risk among the populations reported (ie, some populations may be older or sicker than others). Also, different research methodologies may create artifactual differences among studies as standards for designing studies, terminology, and reporting data have not been uniform. Therefore, these findings may reflect methodological differences and true epidemiological differences among communities. Future reports should include a method, such as an incidence/survival nomogram, to analyze survival rates while taking into account the community incidence rate of cardiac arrest. Further analysis of incidence and survival is necessary to improve intersystem comparisons, a prerequisite to sound decisions about cardiac arrest treatment, health policy, and allocation of resources.
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In contrast to the current consensus that governs the mechanics of prehospital advanced cardiac life support (ACLS), uniform criteria for determining when to initiate, withhold, or terminate ACLS in the field do not exist. Most emergency medical services (EMS) permit paramedics and other prehospital providers to withhold resuscitation when the victim obviously is dead, but the accuracy and appropriateness of this judgement in the field have not been subjected to empiric research. Do-not-resuscitate orders on patients in community settings often are problematic when paramedics and other prehospital providers are governed by standing orders that require them to initiate CPR when it is indicated medically. ⋯ Currently, few services permit paramedics to terminate ACLS in the field when such efforts fail to achieve return of spontaneous circulation. Studies have demonstrated convincingly that the rapid transport of such patients for further attempts at resuscitation in the hospital yields dismal rates of survival. The costs, risks, and benefits of this practice in community settings must be reviewed carefully to allocate EMS resources in an optimal manner.
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When the abdomen is compressed manually in counterpoint to the rhythm of chest compression, in the performance of interposed abdominal compression-CPR, artificial circulation is approximately doubled in animal experiments and in electronic models of the circulatory system. These studies suggest that external manual compression of the abdominal aorta acts like an intra-aortic balloon pump to increase aortic pressure, whereas external manual compression of the abdominal veins acts to prime the right heart and pulmonary vessels before the next chest compression. ⋯ Several clinical studies of this technique have shown promising results including improved hemodynamics, resuscitation success, and survival. The history of interposed abdominal compression-CPR research suggests a number of principles that may be useful in the development of other new methods for the management of cardiac arrest, including the virtues of vigorously pursuing a new idea suggested by serendipitous observations, developing and refining a working hypothesis as to pathophysiologic mechanisms, working in interdisciplinary groups, refining a novel technique in stages as experience is gained, and recognizing the need for staged phase 1, 2, and 3 clinical trials in the context of the approximately ten-year gestation period from laboratory inspiration to clinical practice.
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The Utstein style for uniform reporting of data from out-of-hospital cardiac arrest was developed to solve a major problem in resuscitation research. Outcome measures related to cardiac arrest are difficult to evaluate or compare because there have been no uniform definitions or uniform agreements on what data to report. Widespread acceptance of the Utstein style will lead to a better understanding of out-of-hospital cardiac arrest.
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There is no better place to test life-saving resuscitation interventions than in the prehospital setting. Patients rarely survive cardiac arrest if resuscitation techniques have failed before leaving the scene. ⋯ Most important, by reinforcing standardized care, rigidly scrutinized trials improve patient care, regardless of the effect of the study intervention. The success of productive EMS research centers requires routine communication between hospital and EMS administrators and their medical directors, designation of mutually acceptable data collectors who guarantee confidentiality, reciprocal exchange of study data provided as educational seminars to the hospitals, commitments to support the budget requests of an EMS program and appropriate system modifications, inclusion of EMS personnel in study design from the very beginning, prospective education of the medical community and media before protocol implementation, an authoritative grassroots medical director, and a paramedic supervisor system.