http://www.acc.org/clinical/guidelines/nov96/1999/jac1716pIIa.htm 1999 UPDATED GUIDELINE (WEB VERSION) ACC/AHA Guidelines for the Management of Patients With Acute Myocardial Infarction II. Prehospital Issues Recommendations Class I 1. Availability of 911 access. 2. Availability of an emergency medical services (EMS) system staffed by persons trained to treat cardiac arrest with defibrillation if indicated and to triage patients with ischemic-type chest discomfort. Class IIa 1. Availability of a first-responder defibrillation program in a tiered response system. 2. Healthcare providers educate patients/families about signs and symptoms of acute MI, accessing EMS, and medications. Class IIb 1. Twelve-lead telemetry. 2. Prehospital thrombolysis in special circumstances (eg, transport time greater than 90 minutes). Each year approximately 800 000 persons in the United States experience acute MI, and about 213,000 of them die. At least one half of these persons die within 1 hour of onset of symptoms and before reaching a hospital emergency department.3,4 It has been recognized for more than 3 decades that the majority of these sudden cardiac deaths are the result of fatal arrhythmias that often can be stopped by emergency cardiopulmonary resuscitation (CPR), defibrillation, and prompt ACLS. More recent data regarding the time-dependent benefits of thrombolytic therapy provide added stimulus to develop more effective means of expediting delivery of medical care to persons with acute MI. It has been shown that early treatment results in reductions in mortality, infarct size, and improved LV function.5-7 Clearly, delay in treating patients with suspected acute MI is a critical factor in decreasing the overall survival rate. For these reasons the National Heart, Lung, and Blood Institute (NHLBI) has initiated the National Heart Attack Alert Program (NHAAP), a coordinated national program that extends the ACC/AHA recommendations promoting rapid identification and treatment of patients with acute MI.8,9 Recognition and Management It has been demonstrated that most patients do not seek medical care for 2 hours or more after symptom onset. A sizable proportion wait 12 hours or more. In general, reperfusion therapy beyond 12 hours may offer little benefit.8,9 The components of delay from symptom onset to treatment are (1) patient related (ie, failure to recognize the seriousness of the problem and delay in seeking emergency care); (2) prehospital evaluation, treatment, and transport times; and (3) time required for diagnosis and initiation of treatment in the hospital. In most cases, patient-related delay is the longest, but each component moves the patient further away from the golden first hour to a time when the effect of treatment is lessened. Effective early intervention cannot occur without appropriate patient and family action early after symptom onset. Intervention Strategies Interventions to minimize patient delay are primarily educational in nature and focus on what to do when ischemic-type chest discomfort occurs. Patients with known heart disease or those at high risk of acute MI should be educated by physicians, nurses, and staff about common symptoms of acute MI and appropriate actions to take after symptom onset. Patients should be given an action plan that covers (1) prompt use of aspirin and nitroglycerin if available, (2) how to access EMS, and (3) location of the nearest hospital that offers 24-hour emergency cardiac care. Ideally patients should be given a copy of their resting ECG as a baseline to aid physicians in the emergency department. Because chest discomfort is the most common symptom of infarction,10 patients need simple instructions to respond effectively. In addition to being made aware that chest discomfort may be more of a pressure sensation than actual pain, they should understand that the discomfort can be referred to the arm, throat, and lower jaw and can be accompanied by breathing difficulty, diaphoresis, or a feeling of impending doom.11,12 Reviewing the description of possible symptoms and the action plan in simple, understandable terms at each visit is extremely important, because studies have indicated that many patients minimize the importance of their symptoms or deny the possibility of acute MI.12,13 Discussions with patients should emphasize the importance of acting promptly. Family members should be included in these discussions and enlisted as advocates for action when symptoms of infarction are apparent.8,11 The role of medications to be taken at onset of symptoms must be tailored to each individual. Current advice is to take 1 nitroglycerin tablet sublingually at the onset of ischemic-type chest discomfort and another every 5 minutes for a total of 3 doses. If symptoms persist, the patient should call 911 emergency services or obtain other emergency transportation to the hospital-not the physician's office. The hospital should be staffed round-the-clock by physicians and nurses competent in (1) performing an initial evaluation, including an ECG, (2) providing cardiac monitoring and ACLS, and (3) providing reperfusion therapy. Patients who can be identified in the field as being at high risk with signs of shock, pulmonary congestion, heart rate greater than 100 beats per minute (bpm), and systolic blood pressure less than 100 mm Hg ideally should be triaged to facilities capable of cardiac catheterization and revascularization. Although it has not yet been demonstrated that initial triage of such patients to tertiary centers results in improved outcome compared with initial management in primary facilities, this approach has the desirable effect of obviating the need of emergency transfer of a critically ill patient from one hospital to another, interrupting intensive nursing care and possibly delaying diagnosis and treatment. Use of the EMS system almost always decreases delays in initiation of definitive care.8 Accordingly, the physician should discuss the use of 911 or other local emergency numbers with the patient and should also be aware of the nature and capability of the care that will be rendered. The physician should know whether or not the local EMS system can provide defibrillation and other lifesaving care and should also be familiar with the triage strategy for patients with suspected MI. Emergency Medical Services Systems Each community prehospital EMS system should develop a plan to triage and provide rapid initial medical care to patients with ischemic-type chest discomfort. In most cities in the United States trained emergency medical technicians (EMTs) work in several different healthcare settings: (1) the emergency medical section of the fire department, (2) hospital-based ambulance systems, and (3) department of health services. To minimize time to treatment, particularly for cardiopulmonary arrest, many systems incorporate professional first responders to provide CPR and defibrillation. Ideally there should be a sufficient number of trained personnel so that a first responder can be at the victim's side within 5 minutes. Public service personnel such as police, firefighters, public works employees, and other first-aid providers have frequently been trained successfully as first responders. A sense of urgency in managing patients with ischemic-type chest discomfort must be imparted to EMS personnel. Rapid identification and treatment of the acute MI patient is imperative. Early access to EMS is promoted by a 911 system currently available to 80% of the United States population.8,9 Enhanced 911 systems provide the caller's location, permitting rapid dispatch of prehospital personnel to locations even if the caller is not capable of verbalizing or the dispatcher cannot understand the location of the emergency. Unfortunately the capabilities of EMS systems vary considerably among communities, some providing little beyond first aid, whereas others have formal, advanced protocols for the management of patients with suspected MI or ischemic-type chest discomfort. The latter offers promise in favorably influencing outcomes in such patients. Because patients with acute MI are at relatively high risk of sudden death during the first hour after onset of symptoms, a prehospital EMS system that can provide defibrillation is mandatory.8,14 The survival of patients who develop ischemia-induced ventricular fibrillation (VF) depends on rapid deployment of defibrillation. The survival rate of prehospital treatment for all patients with cardiac arrest (those with and without acute MI) varies from 1% to 25%.15-19 If VF occurs under observation and immediate defibrillation is successful, almost all such patients survive and recover completely.20 Therefore, the AHA has recommended that every ambulance that transports cardiac arrest victims should be equipped with a defibrillator.21 However, this goal is yet to be realized. Automated external defibrillators (AEDs) have been shown to be effective and safe.18,19,21-23 They can be used by first responders with a minimum of training to quickly and accurately analyze rhythms and deliver defibrillation shocks to patients in VF. Systems that incorporate AEDs to shorten response times are highly desirable. Prehospital providers trained and capable of providing ACLS with drugs, intubation, and other therapy further improve the patient's chances for survival. Undirected prehospital assessments of patients with ischemic-type chest discomfort can lead to excessive evaluation times and can impede rapid delivery of appropriate therapy.24 Procedures need to be in place for each EMS system so that a targeted history, physical examination, prehospital ECG, and initial treatment take place in 20 minutes or less. Recently, highly skilled prehospital healthcare providers have been trained and equipped to evaluate patients with ischemic-type chest discomfort by using a checklist and performing 12-lead ECGs in the prehospital setting (Table 1). The checklist should be designed to determine the likelihood of MI and the presence or absence of comorbid conditions and underlying conditions in which thrombolytic therapy may be hazardous. The checklist should facilitate detection of patients with suspected MI who are at especially high risk, including those with tachycardia (>=100 bpm), hypotension (<=100mm Hg), or signs of shock or pulmonary edema. If available, prehospital ECGs should be obtained in all patients with ischemic-type chest discomfort and transmitted to the ED physician for interpretation and instructions. Such advances accelerate the initial diagnosis and administration of thrombolytic agents after the patient's arrival in the ED.5,25,26 Active involvement of local healthcare providers-particularly cardiologists and emergency physicians-is needed to formulate local EMS protocols for patients with suspected MI, provide training, and secure equipment. Virtually all states have regulations and standards for emergency personnel, training, and equipment. It is useful for those involved in the emergency care of patients with acute MI to be familiar with these regulations. Prehospital-Initiated Thrombolysis Randomized controlled trials of fibrinolytic therapy have demonstrated the benefit of initiating thrombolytic therapy as early as possible after onset of ischemic-type chest discomfort.27-29 It seems rational therefore to expect that if thrombolytic therapy could be started at the time of prehospital evaluation, a greater number of lives could be saved. The value of reducing delay until treatment depends not only on the amount of time saved but when it occurs. Available data suggest that time saved within the first 1 to 2 hours has greater biological importance than time saved during the later stages of acute MI.5,7,27,28,30 Several randomized trials of prehospital-initiated thrombolysis have advanced our understanding of the impact of early treatment.5,31-34 Acquisition of ECGs in the field and use of a chest-pain checklist (Table 1) leads to more rapid prehospital and hospital care.5,26 Although none of the individual trials showed a reduction in mortality with prehospital-initiated thrombolytic therapy, a meta-analysis of all available trials demonstrated a 17% relative improvement in outcome associated with prehospital therapy (95% confidence interval [CI], 2% to 29%).34 The greatest improvement in outcome is observed when treatment can be initiated in the field 60 to 90 minutes earlier than in the hospital.5,33-35 Although prehospital-initiated thrombolytic therapy results in earlier treatment, the time savings can be offset in most cases by an improved hospital triage with resultant "door-to-needle time'' reduced to 30 minutes or less.4 However, only a small percentage (5% to 10%) of patients with chest pain in the prehospital setting have acute MI and are eligible for thrombolytic therapy.5,25,36 Ensuring proper selection of patients for therapy can be difficult, and avoiding therapy when it is contraindicated has important medical, legal, and economic implications. For these reasons, a general national policy of prehospital thrombolytic therapy cannot currently be advocated. However, in special settings in which physicians are present in the ambulance or prehospital transport times are 90 minutes or longer, this therapeutic strategy should be considered. Observations from prehospital trials suggest that prehospital systems should focus on early diagnosis (a relatively minor augmentation in prehospital services) instead of delivery of therapy. � 1999 by the American College of Cardiology and American Heart Association, Inc. __________________________________________________ Do You Yahoo!? Try FREE Yahoo! Mail - the world's greatest free email! http://mail.yahoo.com/
