Intensive Care Medicine
Intens. Care Med. 4, 5 - I1 (1978)
9 by Springer-Verlag 1978
Prehospital and Hospital Coronary Care Peter C. Baumann Medizinische Universit~itsklinik, Kantonspital Ziirich, Switzerland
Abstract. This article reviews the current state of services for coronary care. Since the majority of deaths from coronary heart disease occur early and outside the hospital, the importance of the prehospital phase is emphasized. The delay in this period, which is very dangerous for the patient, should be reduced and mobile coronary care units (MCCU's) are one possibility to reduce the rate of sudden coronary death. Different systems of MCCIYs are discussed: (1) those based on a hospital coronary care unit, usually accompanied by a nurse and/or a doctor and (2) those integrated into an already existing decentralized emergency system (e.g. fire department) run by paramedics. Although long-term survival of patients resuscitated from ventricular fibrillation is not so good, the results of many of these units are remarkable.
Key words: Coronary care, Sudden death, Prehospital delay, Mobile coronary care units, Paramedics.
Introduction
mainly within the first hour after symptoms of the acute attack have started [3, 26, 32, 34, 68]; usually called
sudden and unexpected death.
Sudden and Unexpected Coronary Death Sudden death - which can be defined as death within less than one hour after symptoms have started - is the first manifestation of coronary heart disease in 20 to 25% of the patients and therefore is a very important problem in acute coronary care [13, 66]. It frequently occurs with minimal or no warning and - in contrast to cardiogenic shock - these individuals have a good chance of surviving, if effective resuscitation ,is started early. The underlying arrhythmia causing sudden death is usually ventricular fibrillation, which not only occurs in acute myocardial infarction, but also in people with coronary heart disease without myocardial necrosis. Due to the fact that many patients in numerous places have been successfully resuscitated and subsequently discharged home we now know more about the character and prognosis of sudden death:
For almost 20 years the problems of acute coronary care have been recognized and numerous people have tried to solve them. During this period knowledge has increased concerning epidemiology, character and prognosis of acute coronary attacks. Several facts are important and widely accepted: The mortality of patients with acute coronary attacks (myocardial infarction or other acute events in persons with coronary heart disease) is very high: about 50% die within one month [4, 15 ].
1. The risk factors of sudden death are virtually identical with those for coronary heart disease in general [13, 24, 32, 44, 66]. Although many patients have symptoms before they collapse, there are no specific precursors of sudden death which would help to predict or prevent it [1, 13, 18, 21, 53]. According to Liberthson [36] only one third of the patients would have enough time to start any reaction to their symptoms.
The majority of the patients die because ofarrhythmias before they have reached a hospital or seen a doctor -
2. Frequent and/or complex ventricular arrhythmias in patients with coronary heart disease - especially after
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6 a myocardial infarction - obviously increase the incidence of sudden death, but the correlation is not very good and ventricular extrasystoles are rather non-specific. In younger people without evidence of heart disease they seem to have little predictive value [9, 12, 22, 38, 59, 64]. Winkle [73] reports on 94 episodes of ventricular tachycardia in 23 patients which were mainly asymptomatic and usually selflimited. 3. So far it is still not certain whether prophylactic antiarrhythmic therapy is really effective in decreasing the incidence of sudden death. Many studies have been carried out. The double-blind randomized trial with Alprenolol by Wilhelmsson [72] and with Practolol (Multicenter Study [2]) seem to be convincing. All antiarrhythmic agents, however, have their side effects and contraindications and require a strict discipline by the patient and rigid control by his doctor [31, 42, 56, 70]. Lown, too, questions the feasibility of long-term antiarrhytmic therapy but recommends treatment for complex ventricular arrhythmias occuring on exertion or after ventricular fibrillation and myocardial infarction [43, 44]. Rapaport feels that long-term survivors of ventricular fibrillation should be treated prophylacticaUy [54]. 4. The majority of patients who die suddenly have disease of more than one coronary vessel and frequently impaired ventricular function [19, 37, 46, 63, 66, 71]. 5. The recurrence rate in patients resuscitated from ventricular fibrillation is high. In Seattle 26% of 234 longterm survivors developed recurrent ventricular fibrillation during a mean follow-up period of 14 months after discharge from the hospital [56, 71]. In Miami the mean survival after discharge was 12.7 months [36]. 6. People who have had a non-fatal myocardial infarction have a high risk of sudden death [49, 65, 67]. According to Lie [39] site (anterior wall) and size of the infarction as well as moycardial insufficiency and right bundle branch block are important factors for predicting sudden death.
Prehospital Delay There is a considerable delay between the beginning of symptoms and the start of coronary care, and this delay adds up to several hours in places where no special measures for its reduction are undertaken [4, 26]. In Zurich (Switzerland) the total delay for patients with acute myocardial infarction brought to the hospital by ordinary ambulances was 5 hours 10 minutes in the year before the mobile coronary care unit (MCCU) was started [60]. Since any delay in this situation may be deleterious to the patient several recommendations have been made in order to decrease the mortality from acute coronary heart disease:
P.C. Baumann: Prehospital and Hospital Coronary Care 1. The hospital coronary care unit (CCU) can be brought closer to the public by; facilitating the access to the CCU's either by diminishing the administrative impedance to rapid admission or by organizing the emergency department of a hospital in such a way that coronary patients receive adequate supervision and treatment immediately after their arrival; sending coronary ambulances to a patient calling for help because of an acute coronary event. 2. The delay can be reduced sufficiently only if there is information and education of professional and lay people concerning the signs and symptoms of heart attacks and the importance to call for help immediately. the way a patient with cardiac arrest should be resuscitated correctly until the ambulance arrives. It is quite clear, that no recommendation can be made which is applicable to every region. I'm convinced that each area has to find the solution which fits its needs best and which can be incorporated in existing emergency services. Recommendations have been made among others by Yu [74, 75], an expert committee of the WHO [55] and by Lewis [35]. It certainly will be helpful if there is as much coordination as possible of the activities directed toward reduction of sudden coronary death. For instance the performance of a mobile coronary care unit will be improved if at the same time there is good information and education of the population. At the moment a great deal of energy is directed toward mobile coronary care units. They probably would not exist without the experiences which were made in hospital CCU's throughout the world.
Hospital Coronary Care Units In 1962 coronary care units (CCU's) were opened in three different places in the USA and Canada: by Brown in Toronto, by Day in Kansas City and by Meltzer in Philadelphia [17, 48]. The concept of coronary care units was based primarily on three facts: 1. Acute arrhythrnias were recognized as the most frequent cause of death in acute myocardial infarction. 2. At that time it was possible to defibrillate lifethreatening arrhythmias successfully and defibrillators became very important in coronary care. 3. External cardiac massage had been shown to be effective.
P.C. Baumann: Prehospital and Hospital Coronary Care It was obvious that defibrillation was more successful, when it could be performed rapidly after fibrillation had started. Therefore constant supervision and monitoring of patients susceptible to ventricular fibrillation (i.e. patients with acute myocardial infarction) was needed and the necessary equipement had to be available immediately. It then became clear that the incidence of ventricular fibrillation could be reduced if "minor" ventricular arrhythmias often - b u t not always! [38] - preceeding ventricular fibrillation were treated by antiarrhythmic drugs immediately ("R on T", repetitive or multiform ventricular extrasystoles). This means that not only doctors but also nurses treating these patients have to be able to diagnose arrhythmias and initiate therapy. Especially trained coronary care nurses who now are an integral part of CCU's.
is quiet enough. It will be a question of organization to achieve, that the coronary patients receive sufficient attention by skilled personnel even if the nurses of that particular unit have to care for patients with diseases other than myocardial infarction and arrhythmias. If these problems are solved, a combined medical intensive therapy unit does not have disadvantages for the patient [7].
Since CCU's were established, the hospital mortality from myocardial infarction was been lowered by about 5 to 15%. Of course there still is much variation of the mortality between different units e.g. depending on admission policies, mean age of the patients, population characteristics, delay before admission, size of the unit and - of course - the quality of coronary care [7, 10, 621.
In such situations economic arguments might necessarily play a secondary role and these hospitals therefore will have to make a special effort in order to reach a high standard of coronary care.
In many larger hospitals there are CCU's functioning as independent units, run by well-trained nurses under the direction of cardiologists. Without doubt this is a good form of organization as long as there are enough admissions, i.e. at least 200 per year. Bloom calculated an optimal number of 336 CCU beds in 39 CCU's for 5.6 million people in Massachusetts (60 beds per million population), assuming that no patient should have a travel time of more than 30 minutes and that he would have a 95% chance to find an available bed in the nearest CCU. Actually there are 94 CCU's with a total of 446 beds in Massachusetts [6]. Two main problems arise in units which are too small (less than 4 beds): 1. They are not economical if they are equipped for a good performance. According to Frommer [25 ] a unit of less than 4 beds is not feasible from the point of view of personnel utilization or economics. 2. It is difficult for them to maintain a good standard and professional skill of the personnel to cope with all complications of myocardial infarction. Stross [62] found the mortality to be significantly higher in units with less than 60 patients per year. Independent CCU's in middlesized and smaller hospitals will rarely be feasible and the CCU there will be at least combined with a general medical intensive therapy unit. This solution has its obvious advantages but the problem is to give these patients - who often need careful monitoring more than active therapy - an environment which
Finally there are hospitals which are too small to run a CCU. This usually means that they cannot manage patients with acute myocardial infarction. Some of these hospitals are forced to organize some form of coronary care anyhow e.g. for geographic reasons, where otherwise a long journey during a dangerous period of the acute disease would be necessary.
CCU's have their established place in the treatment of acute myocardial infarction, but their effectiveness has been questioned by some authors. Mather [47] showed in a randomized trial, that a selected group of patients with acute myocardial infarction can do as well if treated at home as if treated in a CCU. The question is whether all patients with acute myocardial infarction should initially be treated in a CCU. This question cannot be answered with certainty but for the majority of patients with infarction professional people concerned with the problem would probably give a positive answer [10, 30, 58]. There may be exceptions, e.g. patients with advanced myocardial insufficiency who have no chance of rehabilitation. CCU's have reduced the early hospital mortality from primary ventricular arrhythmias almost to zero. In addition they have contributed much to the understanding of the pathophysiology and the course of the disease as well as to the development of newer methods of treatment. Two major problems, however remained: 1. Mortality from cardiogenic shock could not be reduced by a major degree. 2. The total mortality from coronary heart disease could be influenced only minimally, because prehospital death rate remained high. The organization of mobile coronary care units was an attempt to reduce prehospital mortality.
Mobile Coronary Care Units More than 10 years ago Pantridge realized that it was an advantage to bring coronary care to the patient and to the
P.C. Baumann: Prehospital and Hospital Coronary Care place where the heart attack had occurred instead of bringing the patient to the hospital without monitoring and treatment in a very dangerous period of his illness [50, 51]. Since he started the first mobile coronary care unit (MCCU) in Belfast in January 1966 many others followed him and began to treat the patients, who were victims of acute coronary attacks outside the hospital. Several important observations have been made: 1. Patients can be resuscitated successfully from ventricular fibrillation out-of-hospital and a remarkable precentage survive to leave the hospital [8,14, 29, 36, 50, 51, 54, 561. 2. Arrhythmias play even a more important role in the MCCU than in the hospital CCU. In the earliest phase of acute myocardial infarction there is often an autonomic disturbance with bradycardia and arterial hypotension due to increased vagal tone combined with a lowered threshold for ventricular fibrillation [51, 69]. This condition responds well to Atropine, a therapy which has been questioned by Epstein [20]. There also may be increased sympathetic activity with tachycardia and ventricular arrhythmias that respond to beta-adrenergic blocking drugs. 3. If early arrhythmias can be treated and the haemo= dynamic situation is stabilized promptly the incidence of cardiogenic shock can be lowered according to Pantridge [51]. 4. With the MCCU it was possible to diminish the delay considerably from the beginning of symptoms until coronary care was started. The Belfast unit reaches more than 25% of the patients within one hour from the beginning of symptoms [51 ]. In Zurich the corresponding figure is 21% in a four-year-period. There are many different systems of mobile coronary care: the unit may be based on a hospital CCU and m that case often is accompanied by a CCU-nurse and/or physician. This type of system is used frequently in Europe. The development in the USA was somewhat different. There coronary ambulances are only rarely accompanied by doctors or nurses. The mobile units are usually integrated into already existing, frequently decentralized, emergency systems (fire department, ambulance service, police) and the CCU-nurses, who were often involved in the beginning, were subsequently replaced by paramedical personnel ("paramedics"), who are mainly firemen, ambulance drivers etc. These paramedics were instructed in cardiopulmonary resuscitation including external cardiac massage and endotracheal intubation as well as application of drugs [14, 27, 36, 54, 56]. This type of unit also exists in Europe, e.g. in Brighton, where two ambulances are equipped for resuscitation which is performed by specially trained ambulance drivers [8].
These teams frequently have a good communication system (radio, telephone, ECG telemetry) with the hospital where the patient is supposed to be admitted. As far as I can see there is more reluctance in Europe than in the USA to instruct lay people to perform resuscitative measures in patients with cardiac arrest. In Seattle [14], Miami [36], Brighton [8] the units have remarkably short responding times" and the patient is usually receiving proper therapy within 3 to 5 minutes after the call for help. In many instances this delay might be short enough to allow successful resuscitation even when ventricular fibrillation is the first manifestation, especially if bystanders are able to perform effective resuscitation until the ambulance arrives. Copley demonstrated that if early resuscitation was started by bystanders there were more long-term survivors and there was less myocardial and cerebral damage [16]. In several places up to 25% of those resuscitated survive long term. Liberthson [36] found the prognosis to be better if the heart rate after defibrillation was high. Units .which are accompanied by professional people specially trained in coronary care (nurses, doctors) have their advantages too: they probably can give more specific therapy to the patient. In our experience coronary care outside the hospital not 0nly involves resuscitation but also relief of pain, diagnosis and treatment of (minor) arrhythmias, which are very frequent, as well as clinical evaluation and stabilization of the haemodynamic situation. This possibly can be done better by professional people. The responding time may be somewhat higher and the median delay from the call until the ambulance reaches the patient is 10 minutes in Belfast [51] and Basle [41, 57] and 11 minutes in Zurich [5]. It is obvious that MCCU's cannot be organized in every community. In rural areas e.g. other means have to be looked for in order to reduce the high mortality rate from acute coronary attacks. Advice for an integrated approach to coronary care has been given by several authors [35, 52, 55, 74, 75].
The MCCU in Zurich In Zurich a MCCU was started in March 1972 [5, 23, 29, 61 ]. One ambulance - especially equipped as a mobile intensive therapy unit - is based on the CCU's of two hospitals, the University Hospital (Kantonsspital) and one of the City Hospitals (Stadtspital Triemli). It changes its location each week and the members of the MCCU-team (nurse, doctor, and two ambulance drivers with special training) work in the CCU of the hospital when they are not called to a patient outside the hospital.
P.C. Baumann: Prehospital and Hospital Coronary Care The MCCU is used mainly for patients with acute coronary heart disease but also for people with other acute conditions such as pulmonary edema, severe intoxications, anaphylactic shock etc. During the first four years 2 239 cells were answered by the unit and 1 012 o f these patients had a acute myocardial infarction. 292 patients were resuscitated; in 92 circulatory function could be restored and 40 could leave the hospital later on. Table 1 shows the total delay until coronary care was started in a group of 140 consecutive patients with acute myocardial infarction admitted by ordinary ambulance before the MCCU was started, compared to the MCCUpatients with infarction in the first two years and to the patients with infarction who were admitted by ordinary ambulance in the same period. The delay was considerably shorter in the MCCU-patients which was not only due to a reduction o f the delay due to transportation but also to a shorter delay between patient and doctor.
Conclusions The most important contribution to reduce the rate of sudden unexpected death from coronary heart diseases would be primary prevention of coronary atherosclerosis. This, however, becomes effective only very slowly and will not completely eradicate sudden death. Therefore secondary prevention and aggressive therapy in cases of acute coronary attacks will be necessary - now and in the future. Hospital coronary care units have had their established place in the treatment of coronary heart disease for 15 years. It has become obvious, however, that treatment of acute coronary attacks should start outside the hospital if the mortality is to be further reduced. Since the majority of deaths occur within one hour after symptoms have started it is important to reduce the delay until patients receive adequate therapy. Any region has to solve these problems and to look for a solution that fits its particular situation. One has to remember, that the major delay usually is caused by the patient himself and that frequently he is not aware of the severity of his situation. Information and education is therefore necessary especially for people who already have Signs o f coronaryheart disease. Most probably a good emergency system by itself is a good source o f information for professional and lay people. Not only the patient but also the physician can cause a delay before hospitalization, which should be reduced, and finally the emergency system should function with a minimum of delay and administrative impedance. It is important that the physician is not forced to see every patient before admitting him to a hospital. There
Table 1. Delay from the beginning of symptoms until coronary care was started in patients with acute transmural myocardial infarction in Zurich Coronary care started within 1h
2h
3h
4h
median delay
before MCCU1971-72 3% 14% 27% 37% 5 h l 0 m i n with MCCU1972-74 21% 43% 55% 63% 2h33min withouthY/CCU1972-74 5% 15% 28% 41% 7 h 1 6 m i n
are patients - especially those with symptomatic coronary heart disease and well known to their doctor - who can clearly explain their symptoms by phone. In addition as many qualified people as possible should be familiar with cardiopulmonary resuscitation because resuscitation is better the earlier it is started. There are several possibilities to do something in order to reduce the rate of sudden and early death from coronary heart disease, and is has been shown that these efforts really can be successful. As far as long-term results are concerned we have to be realistic, since we are dealing with a progressive disease which frequently is in an advanced stage already. This fact does not, however, reduce the value and the importance of prehospital and hospital coronary care.
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11 68.Warren, J.V.: Recurrent "sudden death" (editorial). New Engl. J. Med. 293, 298 (1975) 69.Warren, J.V., Lewis, R.P.: Beneficial effects of Atropine in the prehospital phase of coronary care. Amer. J. Cardiol. 37, 68 (1976) 70.Weaver, W.D., Cobb, L.A., Hallstrom, A.P., Hedgecock, M.: Significance of ventricular dysrhythmias during ambulatory monitoring in patients resuscitated from the sudden death syndrome (abstract). Circulation 54, Suppl. II, 172 (1976) 71.Weaver, W.D., Lorch, G.S., Alvarez, H.A., Cobb, L.A.: Anglographic findings and prognostic indicators in patients resuscitated from sudden cardiac, death. Circulation 54, 895 (1976) 72.Wilhelmsson, C., Vedin, J.A., Wilhelmsen, L., Tibblin, G., Werk6, L.: Reduction of sudden deaths after myocardial infarction by treatment with Alprenolol. Preliminary results. Lancet 1974 II, 1157 73.Winkle, R.A., Derrington, D.C., Schroeder, J.S.: Characteristics of ventricular tachycardia in ambulatory patients. Amer. J. Cardiol. 39, 487 (1977) 74.Yu, P.N.: A stratified system of coronary care (editorial). Circulation 44, 979 (1971) 75.Yu, P.N.: Prehospital care of acute myocardial infarction. Circulation 45,189 (1972) Dr. P.C. Baumann Leitender Arzt der Intensivstation Medizinische Universit~itsklinik Kantonsspital CH - 8091 Ziirich Switzerland
Intens. Care Med. 4, 5 - I1 (1978)
9 by Springer-Verlag 1978
Prehospital and Hospital Coronary Care Peter C. Baumann Medizinische Universit~itsklinik, Kantonspital Ziirich, Switzerland
Abstract. This article reviews the current state of services for coronary care. Since the majority of deaths from coronary heart disease occur early and outside the hospital, the importance of the prehospital phase is emphasized. The delay in this period, which is very dangerous for the patient, should be reduced and mobile coronary care units (MCCU's) are one possibility to reduce the rate of sudden coronary death. Different systems of MCCIYs are discussed: (1) those based on a hospital coronary care unit, usually accompanied by a nurse and/or a doctor and (2) those integrated into an already existing decentralized emergency system (e.g. fire department) run by paramedics. Although long-term survival of patients resuscitated from ventricular fibrillation is not so good, the results of many of these units are remarkable.
Key words: Coronary care, Sudden death, Prehospital delay, Mobile coronary care units, Paramedics.
Introduction
mainly within the first hour after symptoms of the acute attack have started [3, 26, 32, 34, 68]; usually called
sudden and unexpected death.
Sudden and Unexpected Coronary Death Sudden death - which can be defined as death within less than one hour after symptoms have started - is the first manifestation of coronary heart disease in 20 to 25% of the patients and therefore is a very important problem in acute coronary care [13, 66]. It frequently occurs with minimal or no warning and - in contrast to cardiogenic shock - these individuals have a good chance of surviving, if effective resuscitation ,is started early. The underlying arrhythmia causing sudden death is usually ventricular fibrillation, which not only occurs in acute myocardial infarction, but also in people with coronary heart disease without myocardial necrosis. Due to the fact that many patients in numerous places have been successfully resuscitated and subsequently discharged home we now know more about the character and prognosis of sudden death:
For almost 20 years the problems of acute coronary care have been recognized and numerous people have tried to solve them. During this period knowledge has increased concerning epidemiology, character and prognosis of acute coronary attacks. Several facts are important and widely accepted: The mortality of patients with acute coronary attacks (myocardial infarction or other acute events in persons with coronary heart disease) is very high: about 50% die within one month [4, 15 ].
1. The risk factors of sudden death are virtually identical with those for coronary heart disease in general [13, 24, 32, 44, 66]. Although many patients have symptoms before they collapse, there are no specific precursors of sudden death which would help to predict or prevent it [1, 13, 18, 21, 53]. According to Liberthson [36] only one third of the patients would have enough time to start any reaction to their symptoms.
The majority of the patients die because ofarrhythmias before they have reached a hospital or seen a doctor -
2. Frequent and/or complex ventricular arrhythmias in patients with coronary heart disease - especially after
0340-0964/78/0004/0005/$1.40
6 a myocardial infarction - obviously increase the incidence of sudden death, but the correlation is not very good and ventricular extrasystoles are rather non-specific. In younger people without evidence of heart disease they seem to have little predictive value [9, 12, 22, 38, 59, 64]. Winkle [73] reports on 94 episodes of ventricular tachycardia in 23 patients which were mainly asymptomatic and usually selflimited. 3. So far it is still not certain whether prophylactic antiarrhythmic therapy is really effective in decreasing the incidence of sudden death. Many studies have been carried out. The double-blind randomized trial with Alprenolol by Wilhelmsson [72] and with Practolol (Multicenter Study [2]) seem to be convincing. All antiarrhythmic agents, however, have their side effects and contraindications and require a strict discipline by the patient and rigid control by his doctor [31, 42, 56, 70]. Lown, too, questions the feasibility of long-term antiarrhytmic therapy but recommends treatment for complex ventricular arrhythmias occuring on exertion or after ventricular fibrillation and myocardial infarction [43, 44]. Rapaport feels that long-term survivors of ventricular fibrillation should be treated prophylacticaUy [54]. 4. The majority of patients who die suddenly have disease of more than one coronary vessel and frequently impaired ventricular function [19, 37, 46, 63, 66, 71]. 5. The recurrence rate in patients resuscitated from ventricular fibrillation is high. In Seattle 26% of 234 longterm survivors developed recurrent ventricular fibrillation during a mean follow-up period of 14 months after discharge from the hospital [56, 71]. In Miami the mean survival after discharge was 12.7 months [36]. 6. People who have had a non-fatal myocardial infarction have a high risk of sudden death [49, 65, 67]. According to Lie [39] site (anterior wall) and size of the infarction as well as moycardial insufficiency and right bundle branch block are important factors for predicting sudden death.
Prehospital Delay There is a considerable delay between the beginning of symptoms and the start of coronary care, and this delay adds up to several hours in places where no special measures for its reduction are undertaken [4, 26]. In Zurich (Switzerland) the total delay for patients with acute myocardial infarction brought to the hospital by ordinary ambulances was 5 hours 10 minutes in the year before the mobile coronary care unit (MCCU) was started [60]. Since any delay in this situation may be deleterious to the patient several recommendations have been made in order to decrease the mortality from acute coronary heart disease:
P.C. Baumann: Prehospital and Hospital Coronary Care 1. The hospital coronary care unit (CCU) can be brought closer to the public by; facilitating the access to the CCU's either by diminishing the administrative impedance to rapid admission or by organizing the emergency department of a hospital in such a way that coronary patients receive adequate supervision and treatment immediately after their arrival; sending coronary ambulances to a patient calling for help because of an acute coronary event. 2. The delay can be reduced sufficiently only if there is information and education of professional and lay people concerning the signs and symptoms of heart attacks and the importance to call for help immediately. the way a patient with cardiac arrest should be resuscitated correctly until the ambulance arrives. It is quite clear, that no recommendation can be made which is applicable to every region. I'm convinced that each area has to find the solution which fits its needs best and which can be incorporated in existing emergency services. Recommendations have been made among others by Yu [74, 75], an expert committee of the WHO [55] and by Lewis [35]. It certainly will be helpful if there is as much coordination as possible of the activities directed toward reduction of sudden coronary death. For instance the performance of a mobile coronary care unit will be improved if at the same time there is good information and education of the population. At the moment a great deal of energy is directed toward mobile coronary care units. They probably would not exist without the experiences which were made in hospital CCU's throughout the world.
Hospital Coronary Care Units In 1962 coronary care units (CCU's) were opened in three different places in the USA and Canada: by Brown in Toronto, by Day in Kansas City and by Meltzer in Philadelphia [17, 48]. The concept of coronary care units was based primarily on three facts: 1. Acute arrhythrnias were recognized as the most frequent cause of death in acute myocardial infarction. 2. At that time it was possible to defibrillate lifethreatening arrhythmias successfully and defibrillators became very important in coronary care. 3. External cardiac massage had been shown to be effective.
P.C. Baumann: Prehospital and Hospital Coronary Care It was obvious that defibrillation was more successful, when it could be performed rapidly after fibrillation had started. Therefore constant supervision and monitoring of patients susceptible to ventricular fibrillation (i.e. patients with acute myocardial infarction) was needed and the necessary equipement had to be available immediately. It then became clear that the incidence of ventricular fibrillation could be reduced if "minor" ventricular arrhythmias often - b u t not always! [38] - preceeding ventricular fibrillation were treated by antiarrhythmic drugs immediately ("R on T", repetitive or multiform ventricular extrasystoles). This means that not only doctors but also nurses treating these patients have to be able to diagnose arrhythmias and initiate therapy. Especially trained coronary care nurses who now are an integral part of CCU's.
is quiet enough. It will be a question of organization to achieve, that the coronary patients receive sufficient attention by skilled personnel even if the nurses of that particular unit have to care for patients with diseases other than myocardial infarction and arrhythmias. If these problems are solved, a combined medical intensive therapy unit does not have disadvantages for the patient [7].
Since CCU's were established, the hospital mortality from myocardial infarction was been lowered by about 5 to 15%. Of course there still is much variation of the mortality between different units e.g. depending on admission policies, mean age of the patients, population characteristics, delay before admission, size of the unit and - of course - the quality of coronary care [7, 10, 621.
In such situations economic arguments might necessarily play a secondary role and these hospitals therefore will have to make a special effort in order to reach a high standard of coronary care.
In many larger hospitals there are CCU's functioning as independent units, run by well-trained nurses under the direction of cardiologists. Without doubt this is a good form of organization as long as there are enough admissions, i.e. at least 200 per year. Bloom calculated an optimal number of 336 CCU beds in 39 CCU's for 5.6 million people in Massachusetts (60 beds per million population), assuming that no patient should have a travel time of more than 30 minutes and that he would have a 95% chance to find an available bed in the nearest CCU. Actually there are 94 CCU's with a total of 446 beds in Massachusetts [6]. Two main problems arise in units which are too small (less than 4 beds): 1. They are not economical if they are equipped for a good performance. According to Frommer [25 ] a unit of less than 4 beds is not feasible from the point of view of personnel utilization or economics. 2. It is difficult for them to maintain a good standard and professional skill of the personnel to cope with all complications of myocardial infarction. Stross [62] found the mortality to be significantly higher in units with less than 60 patients per year. Independent CCU's in middlesized and smaller hospitals will rarely be feasible and the CCU there will be at least combined with a general medical intensive therapy unit. This solution has its obvious advantages but the problem is to give these patients - who often need careful monitoring more than active therapy - an environment which
Finally there are hospitals which are too small to run a CCU. This usually means that they cannot manage patients with acute myocardial infarction. Some of these hospitals are forced to organize some form of coronary care anyhow e.g. for geographic reasons, where otherwise a long journey during a dangerous period of the acute disease would be necessary.
CCU's have their established place in the treatment of acute myocardial infarction, but their effectiveness has been questioned by some authors. Mather [47] showed in a randomized trial, that a selected group of patients with acute myocardial infarction can do as well if treated at home as if treated in a CCU. The question is whether all patients with acute myocardial infarction should initially be treated in a CCU. This question cannot be answered with certainty but for the majority of patients with infarction professional people concerned with the problem would probably give a positive answer [10, 30, 58]. There may be exceptions, e.g. patients with advanced myocardial insufficiency who have no chance of rehabilitation. CCU's have reduced the early hospital mortality from primary ventricular arrhythmias almost to zero. In addition they have contributed much to the understanding of the pathophysiology and the course of the disease as well as to the development of newer methods of treatment. Two major problems, however remained: 1. Mortality from cardiogenic shock could not be reduced by a major degree. 2. The total mortality from coronary heart disease could be influenced only minimally, because prehospital death rate remained high. The organization of mobile coronary care units was an attempt to reduce prehospital mortality.
Mobile Coronary Care Units More than 10 years ago Pantridge realized that it was an advantage to bring coronary care to the patient and to the
P.C. Baumann: Prehospital and Hospital Coronary Care place where the heart attack had occurred instead of bringing the patient to the hospital without monitoring and treatment in a very dangerous period of his illness [50, 51]. Since he started the first mobile coronary care unit (MCCU) in Belfast in January 1966 many others followed him and began to treat the patients, who were victims of acute coronary attacks outside the hospital. Several important observations have been made: 1. Patients can be resuscitated successfully from ventricular fibrillation out-of-hospital and a remarkable precentage survive to leave the hospital [8,14, 29, 36, 50, 51, 54, 561. 2. Arrhythmias play even a more important role in the MCCU than in the hospital CCU. In the earliest phase of acute myocardial infarction there is often an autonomic disturbance with bradycardia and arterial hypotension due to increased vagal tone combined with a lowered threshold for ventricular fibrillation [51, 69]. This condition responds well to Atropine, a therapy which has been questioned by Epstein [20]. There also may be increased sympathetic activity with tachycardia and ventricular arrhythmias that respond to beta-adrenergic blocking drugs. 3. If early arrhythmias can be treated and the haemo= dynamic situation is stabilized promptly the incidence of cardiogenic shock can be lowered according to Pantridge [51]. 4. With the MCCU it was possible to diminish the delay considerably from the beginning of symptoms until coronary care was started. The Belfast unit reaches more than 25% of the patients within one hour from the beginning of symptoms [51 ]. In Zurich the corresponding figure is 21% in a four-year-period. There are many different systems of mobile coronary care: the unit may be based on a hospital CCU and m that case often is accompanied by a CCU-nurse and/or physician. This type of system is used frequently in Europe. The development in the USA was somewhat different. There coronary ambulances are only rarely accompanied by doctors or nurses. The mobile units are usually integrated into already existing, frequently decentralized, emergency systems (fire department, ambulance service, police) and the CCU-nurses, who were often involved in the beginning, were subsequently replaced by paramedical personnel ("paramedics"), who are mainly firemen, ambulance drivers etc. These paramedics were instructed in cardiopulmonary resuscitation including external cardiac massage and endotracheal intubation as well as application of drugs [14, 27, 36, 54, 56]. This type of unit also exists in Europe, e.g. in Brighton, where two ambulances are equipped for resuscitation which is performed by specially trained ambulance drivers [8].
These teams frequently have a good communication system (radio, telephone, ECG telemetry) with the hospital where the patient is supposed to be admitted. As far as I can see there is more reluctance in Europe than in the USA to instruct lay people to perform resuscitative measures in patients with cardiac arrest. In Seattle [14], Miami [36], Brighton [8] the units have remarkably short responding times" and the patient is usually receiving proper therapy within 3 to 5 minutes after the call for help. In many instances this delay might be short enough to allow successful resuscitation even when ventricular fibrillation is the first manifestation, especially if bystanders are able to perform effective resuscitation until the ambulance arrives. Copley demonstrated that if early resuscitation was started by bystanders there were more long-term survivors and there was less myocardial and cerebral damage [16]. In several places up to 25% of those resuscitated survive long term. Liberthson [36] found the prognosis to be better if the heart rate after defibrillation was high. Units .which are accompanied by professional people specially trained in coronary care (nurses, doctors) have their advantages too: they probably can give more specific therapy to the patient. In our experience coronary care outside the hospital not 0nly involves resuscitation but also relief of pain, diagnosis and treatment of (minor) arrhythmias, which are very frequent, as well as clinical evaluation and stabilization of the haemodynamic situation. This possibly can be done better by professional people. The responding time may be somewhat higher and the median delay from the call until the ambulance reaches the patient is 10 minutes in Belfast [51] and Basle [41, 57] and 11 minutes in Zurich [5]. It is obvious that MCCU's cannot be organized in every community. In rural areas e.g. other means have to be looked for in order to reduce the high mortality rate from acute coronary attacks. Advice for an integrated approach to coronary care has been given by several authors [35, 52, 55, 74, 75].
The MCCU in Zurich In Zurich a MCCU was started in March 1972 [5, 23, 29, 61 ]. One ambulance - especially equipped as a mobile intensive therapy unit - is based on the CCU's of two hospitals, the University Hospital (Kantonsspital) and one of the City Hospitals (Stadtspital Triemli). It changes its location each week and the members of the MCCU-team (nurse, doctor, and two ambulance drivers with special training) work in the CCU of the hospital when they are not called to a patient outside the hospital.
P.C. Baumann: Prehospital and Hospital Coronary Care The MCCU is used mainly for patients with acute coronary heart disease but also for people with other acute conditions such as pulmonary edema, severe intoxications, anaphylactic shock etc. During the first four years 2 239 cells were answered by the unit and 1 012 o f these patients had a acute myocardial infarction. 292 patients were resuscitated; in 92 circulatory function could be restored and 40 could leave the hospital later on. Table 1 shows the total delay until coronary care was started in a group of 140 consecutive patients with acute myocardial infarction admitted by ordinary ambulance before the MCCU was started, compared to the MCCUpatients with infarction in the first two years and to the patients with infarction who were admitted by ordinary ambulance in the same period. The delay was considerably shorter in the MCCU-patients which was not only due to a reduction o f the delay due to transportation but also to a shorter delay between patient and doctor.
Conclusions The most important contribution to reduce the rate of sudden unexpected death from coronary heart diseases would be primary prevention of coronary atherosclerosis. This, however, becomes effective only very slowly and will not completely eradicate sudden death. Therefore secondary prevention and aggressive therapy in cases of acute coronary attacks will be necessary - now and in the future. Hospital coronary care units have had their established place in the treatment of coronary heart disease for 15 years. It has become obvious, however, that treatment of acute coronary attacks should start outside the hospital if the mortality is to be further reduced. Since the majority of deaths occur within one hour after symptoms have started it is important to reduce the delay until patients receive adequate therapy. Any region has to solve these problems and to look for a solution that fits its particular situation. One has to remember, that the major delay usually is caused by the patient himself and that frequently he is not aware of the severity of his situation. Information and education is therefore necessary especially for people who already have Signs o f coronaryheart disease. Most probably a good emergency system by itself is a good source o f information for professional and lay people. Not only the patient but also the physician can cause a delay before hospitalization, which should be reduced, and finally the emergency system should function with a minimum of delay and administrative impedance. It is important that the physician is not forced to see every patient before admitting him to a hospital. There
Table 1. Delay from the beginning of symptoms until coronary care was started in patients with acute transmural myocardial infarction in Zurich Coronary care started within 1h
2h
3h
4h
median delay
before MCCU1971-72 3% 14% 27% 37% 5 h l 0 m i n with MCCU1972-74 21% 43% 55% 63% 2h33min withouthY/CCU1972-74 5% 15% 28% 41% 7 h 1 6 m i n
are patients - especially those with symptomatic coronary heart disease and well known to their doctor - who can clearly explain their symptoms by phone. In addition as many qualified people as possible should be familiar with cardiopulmonary resuscitation because resuscitation is better the earlier it is started. There are several possibilities to do something in order to reduce the rate of sudden and early death from coronary heart disease, and is has been shown that these efforts really can be successful. As far as long-term results are concerned we have to be realistic, since we are dealing with a progressive disease which frequently is in an advanced stage already. This fact does not, however, reduce the value and the importance of prehospital and hospital coronary care.
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