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teams may simply reflect a reporting bias associated with the staffing levels and structure of rapid-response teams at academic centers. In terv en tions a nd Ou t comes As noted above, the most common conditions that trigger the rapid-response system are acute respiratory failure, acute cardiac failure, acute changes in consciousness, hypotension, arrhythmias, pulmonary edema, and sepsis.24 An audit of conditions that trigger the rapid-response team within an institution permits the development of specific preventive and response strategies. Some interventions performed by the response team are simple (administration of oxygen, intravenous fluids, diuretics, and bronchodilators and performance of diagnostic tests). However, many patients require critical care interventions.6 Some evidence suggests that the system can also help address the planning of end-of-life care.25,41 Effect on Patient Outcomes The only multicenter, cluster-randomized, controlled trial of medical emergency teams is the MERIT study.25 After 2 months of observation and 4 months of preparation, the MERIT investigators randomly assigned 12 Australian hospitals to medical-emergency-team implementation and 11 to continued standard care for 6 months. On primary analysis, MERIT showed that implementation of the medical emergency team was not associated with a decrease in cardiac arrests, ICU admissions, or unexpected deaths. A post hoc analysis of the MERIT study showed a significant improvement in outcomes (fewer deaths and cardiac arrests) when the data were analyzed in an as-treated model rather than an intention-to-treat (as-assigned) model. These findings, however, are hypothesis-generating at best. In this analysis, there was also a significant and linear decrease in poor outcomes as medical-emergency-team responses increased,42 a finding similar to that of a single-center study.43 The implications of the MERIT study remain the subject of much debate, because of issues of statistical power, data analysis, study design and execution, and contamination (delivery of the intervention [medical emergency team] in control hospitals by using the code team to assess patients not in cardiac arrest or respiratory arrest). A few nonThe New England Journal of Medicine Downloaded from nejm.org at UNIVERSITY OF PITTSBURGH on May 30, 2012. For personal use only. No other uses without permission. Copyright © 2011 Massachusetts Medical Society. All rights reserved. current concepts n engl j med 365;2 nejm.org july 14, 2011 143 randomized, single-center, before-and-after trials have shown improved outcomes with rapidresponse teams,6-11 but their level of evidence is low. Two meta-analyses have failed to show a decrease in the rate of cardiac arrests in association with implementation of a rapid-response system.13,14 Thus, the effectiveness of such systems remains uncertain and a matter of controversy. Other Potential Effects The relatively controlled environment provided by a quality-improvement analysis of the activities of the rapid-response system permits bedside and conference-room education of nursing and medical staff.44 Australian and Canadian nurses report that involvement in rapid-response systems teaches them how to provide better care for acutely ill patients.45,46 In addition, such systems may contribute to better decision making about end-oflife care.25,41 Potential adverse effects of the implementation of a rapid-response system include additional cost, diversion of resources that could be used to care for critically ill patients, desensitization to emergencies, and a decreased sense of responsibility for patients on the part of the hospital-ward team. S tr ategies for Successful Implemen tation The introduction of a rapid-response system is associated with many logistic, political, anthropologic, social, and medical challenges. They must be carefully considered, and a coordinated strategy must be applied to avoid implementation failure.47 A rapid-response system is unlikely to succeed without support from hospital leaders, including senior medical and nursing personnel.47 Up to 1 year may be required to explain the concept of the rapid response system and to obtain support for its