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Cardiac arrest, chain of survival and Utstein style

Gullo, A.

European Journal of Anaesthesiology: September 2002 - Volume 19 - Issue 9 - p 624-633
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Cardiac arrest is a dramatic condition leading to sudden death if someone cannot perform two interventions, basic life support and early defibrillation, that have been proved to improve long-term survival. The modern era of cardiopulmonary resuscitation began with a description of closed chest cardiac massage by Kouwenhoven in 1960. Research to make advances in cardiac arrest is a very difficult task. Experts set up a series of guidelines that represent a keystone for educational needs and evolving technology. There is a consensus that the highest potential survival rate from cardiac arrest can only be achieved when the following sequence of events occurs as rapidly as possible: (1) recognition of early warning signs, (2) activation of the emergency medical services, (3) basic cardiopulmonary resuscitation, (4) cardiac defibrillation, (5) management of the airway and ventilation of the lungs, and (6) intravenous (i.v.) administration of medications. These events are necessary for any success of emergency cardiovascular care. They are linked in a chain of survival. The links in the adult chain of survival are: early access; early CPR; early defibrillation; and early acute cardiac life support. The 'Utstein style', recently introduced, represents a standard of practice both inside and outside hospital with recommended guidelines for the uniform reporting of clinical data from the patient suffering cardiac arrest. According to the concept of the chain of survival, the Utstein style delineates time and establishes a set of core and supplemental times to be recorded that provide important characteristics of the response of victims of cardiac arrest.

Trieste University Medical School, Department of Clinical Sciences, Section of Anaesthesia, Intensive Care and Pain Clinic, Trieste, Italy

Correspondence to: Antonino Gullo, Department of Clinical Sciences - Section of Annesthesia, Intensive Care and Pain Clinic, Trieste University Hospital, School of Medicine, Trieste, Italy. E-mail: gullo@univ.trieste.it; Tel: +39 040 3994540; Fax: +39 040 912278

Accepted for publication August 2001 EJA 763

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Magnitude of the problem

Cardiac arrest is a dramatic clinical event that can occur suddenly and often without premonitory signs. This condition is characterized by sudden loss of consciousness due to the lack of adequate cerebral blood flow, which occurs when the heart ceases to pump. A cardiac arrest is a potentially reversible condition if resuscitation has begun swiftly, but it is fatal if no such intervention takes place. Obviously in this case, one refers to sudden death. The epidemiology of this dangerous situation has been well documented. Because of the several predisposing factors and the complexity of the mechanisms that may be involved, sudden death is considered as a unique condition and represents a real challenge to researchers and clinicians. Many clinical studies and reports since 1960, considered the year in which modem research into this problem began [1], have created substantial interest and laid the basics for guidelines [2-9]. Nevertheless, despite this activity, the results are not encouraging, partly because experimental and clinical research is hampered by inadequate funding [10]. Guidelines have been defined as systematically developed statements with the scope of helping the practising physician and the patient to develop appropriate decisions about specific clinical circumstances [11].

Some guidelines are declarations and categorically state what should or should not be done. Others suggest a range of actions that are appropriate or acceptable with the aim of obtaining a particular result. Because such guidelines make explicit what many clinicians tend to keep implicit, critical appraisal of guidelines requires an understanding of how the developers of guidelines identified, appraised and summarized the evidence, and how they chose the value reflected in their recommendations. To determine whether guidelines are applicable in our practice, we looked for clear and concise recommendations about specific populations, describing common options linked to clinically important outcomes. Guidelines must be considered in the light of local skills, culture and resources, and need to be adaptable to different patients and settings [12]. Guidelines are an attempt to refine a substantial and often variegated mass of knowledge into a simple and easily usable format [13] that allows easier and more organized data collection and a more precise comparison between different realities. Guidelines about life-support measures are particularly important since they must deal not only with the 'pure' therapeutic phase, but also with the training of medical and nursing personnel, and indeed lay persons. In fact, they establish the most appropriate training for all these categories of people to obtain an acceptable result using the minimum of resources and without prejudicing the smallest chance for the patient, even if a given action is carried out by persons other than physicians and nurses.

The European Guidelines on Cardiorespiratory Resuscitation were developed by the European Resuscitation Council (ERC) and published in 1992 and 1998. They are divided into sections on basic life support (BLS) [7] and advanced life support (ALS) [8]. Both focus on the aspects inherent to cardiac arrest: the importance of early defibrillation and the simplification of the training of BLS manoeuvres. The homogenization of the different methods of training and the pharmacological approach to cardiopulmonary resuscitation (CPR) were first tackled in Europe with great effort but have not yet, despite the formation of the European Union, produced satisfactory results. A clear example is that a unique telephone number to activate the emergency healthcare system in any country is still far from being adopted universally. Furthermore, since the differences between the US and European guidelines are considerable, it has been necessary to create committees of experts who have tried, for the first time, to promote 'world-wide' guidelines using the involvement of important associations that have worked to draft a series of recommendations [8,14-20]. The documents produced are being integrated, both with regard to the training programmes and the therapeutic protocols, in the various realities involved. However, guidelines per se do not and cannot represent absolute and immutable knowledge, but must be periodically updated in the light of the most recent information. It is sufficient to consider the changes witnessed over the last 10 years in the advanced treatment of cardiac arrest (alkalinizing drugs and calcium are practically no longer used). Now there is the recent hypothesis that lung ventilation might be unnecessary, at least in the first few minutes [21], with all the consequent advantages of simplifying training of lay men as the ABC manoeuvres become simply 'AC'. The right compromise will be difficult to achieve, but the initial direction seems correct and in those countries where verification of training and therapeutic protocols are underway, the results seem encouraging [22]. There are no national statistics on survival of out-of-hospital ventricular fibrillation in the USA. Communities report rates ranging from 4 to 33% [23-25]. The higher rates are in those communities that can provide rapid links [26]. With inpatient cardiac arrest, the survival rates are variously reported as 0-29% [27]. When CPR manoeuvres are performed within 4 min after the patient's collapse, the likelihood of survival to hospital discharge doubles [28]. Automated external defibrillators (AED) have been available in recent decades and have became more routinely used everywhere [29]. The devices are very sensitive and specific [30-32]. An AED automatically interprets the cardiac rhythm and if ventricular fibrillation is detected it advises the operator to administer a countershock.

Public access defibrillation (PAD) is a novel treatment for out-of-hospital sudden cardiac arrest that refers to the use of AED by the lay public or by non-medical personnel such as the police [33]. Questions yet to be answered on the appropriate use of AED in PAD settings concern: training and retraining issues, device maintenance, and collection of accurate data to evaluate benefits and to identify areas of needed improvement or expansion of AED availability [34].

Recently, Stiell and colleagues have shown evidence of a significant improvement in patient survival after cardiac arrest in a large BLS EMS system [35]. In addition to the treatment of the underlying disease, therapy for patients with ventricular dysrhythmias includes antidysrhythmic drugs and implantable cardioverter defibrillators (ICD) [36-39]. Use of antidysrhythmic drugs is limited by their potential harmful effect [40]. Since their introduction in the 1980s, numerous reports have shown that ICDs decrease sudden cardiac death in patients with sustained ventricular dysrhythmias [41]. The cost-effectiveness of ICD therapy appears favourable, given the marked survival benefit seen in randomized trials relative to antidysrhythmic drug treatment [42].

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Definition and epidemiology of sudden death

Sudden death is characterized by some key features. It is a natural event since violent external causes are excluded, and it occurs without warning in an individual without a known disease and without it being in any way predictable. It is considered unexpected if, on the other hand, it occurs in patients with disease, albeit severe, but improving clinically or in a phase of stability. The evolution is rapid, within an hour of the onset of acute symptoms that bear witness to the presence of a physiological process that has caused irreversible damage. In defining sudden death to satisfy clinical, legal and social criteria, four time elements should be considered:

  • Risk factors and premonitory symptoms;
  • Precipitation of the terminal event;
  • Cardiac arrest real and proper;
  • Biological death.

Systemic hypertension is also significantly related to the incidence of sudden death because of the increased risk of ventricular dysrhythmias that this condition carries. Smokers, too, are at risk. Intraventricular conduction defects, obesity, dyslipidaemia, diabetes mellitus, stress and social isolation are all conditions that predispose to sudden death.

A low ventricular ejection fraction, left ventricular hypertrophy, myocardiopathy, ventricular aneurysm, heart failure and compromised coronary arteries are all further situations that predispose to sudden death even at a subclinical stage. Patients at risk of sudden death may have symptoms of chest pain, dyspnoea, fatigue and a whole series of non-specific disturbances, e.g. insomnia, such as to give them a fore-boding of an acute event and lead them to contact their doctor in the weeks or months preceding the cardiac arrest. Nevertheless, only a minority of victims of sudden death give importance to premonitory symptoms and are convinced of the need to see a doctor.

Precipitating situations related to intense physical effort or psychophysical stress may have taken place in the hours preceding sudden death. These are situations that cause an increase in sympathetic tone and a reduction in vagal tone. Episodes of tachycardia and ventricular extrasystoles are more frequent preceding ventricular fibrillation. Asystole, electromechanical dissociation and ventricular fibrillation are classic conditions that lead to sudden death; ventricular fibrillation without a pulse and pulseless electrical activity (PEA) are conditions whose swift recognition is vital for early and often life-saving interventions. In fact, cardiac arrest, which is characterized by sudden loss of consciousness caused by inadequate cerebral blood flow, is a condition still reversible if correct resuscitation measures are quickly put into practice.

The positive outcome of support measures is related to the mechanism responsible for the cardiac arrest, from the time elapsed between the event and the first-aid measures, individual pathophysiological features and the clinical condition of the patient. In cases of cardiac arrest occurring out of hospital, the first rhythm recorded by emergency aid personnel is important because it is related to the success of the resuscitation manoeuvres. Patients with ventricular fibrillation or a pulseless ventricular tachycardia have a better prognosis than the patient found with bradydysrhythmia, asystole or with electromechanical dissociation.

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Chain of survival

In 1991, Cummins and colleagues [43] analysed the various stages of aid from different US emergency services. They introduced the concept of a 'chain of survival' in respect of those patients who had suffered a cardiac arrest outside the hospital setting. This is a particular sequence of events that, if closely connected and put into action as quickly as possible, can lead to a significant increase in the number of patients who are discharged from hospital alive. The chain has four links that must be 'strengthened' by specialized theoretical and practical programmes co-ordinated by the Emergency Department. This is to avoid any risk of a decrease in the final performance and a consequent low percentage of patients surviving a cardiac arrest occurring in the community. This process can be divided into four different phases:

  • Early access;
  • Basic life support (early BLS);
  • Early defibrillation;
  • Advanced life support (early ALS).

These will be described briefly to clarify the validity of the concept of chain of survival.

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Early access

A cardiac arrest is the most classical and dramatic medical emergency: the condition must be recognized by any witnesses of the event, and the services designated to respond to the emergency must be contacted efficiently. In the case of sudden death, the time of intervention starts the moment the patient collapses and continues while the state of the emergency is recognized by bystanders, who then decide to call for help, perhaps needing to find a telephone and/or the right number to call. When the operator responds, the caller will be first questioned and then arrangements made to send an ambulance or other means of aid. The time of intervention relates to the moment when the ambulance personnel receive the call until they reach the scene of the event. Perhaps more time passes as the aider reaches the patient and makes an examination. Thus, precious minutes pass even before resuscitation measures are started. Information and educational programmes must be directed towards the general population, and in particular to those people who, for various reasons, may have previously witnessed a cardiac arrest. At the same time, the communication system used to activate the first-aid services must be made more efficient. A large step forward towards this increased efficiency was made recently with the introduction of a single telephone number for emergency healthcare services, and in some countries with more advanced healthcare structures there is a trend towards covering the whole national territory with this system. Obviously, swift access by emergency aid services means that BLS, defibrillation and ALS can all be started much earlier.

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Early BLS

BLS must be started immediately after recognition of a cardiac arrest, simultaneously with alerting the emergency organization. The priority is to start external cardiac massage and artificial ventilation of the lungs to maintain even a minimum of perfusion and oxygenation of the brain and myocardium until it is possible to start more advanced resuscitation treatment. Time is fundamental. In fact, for support measures to have a chance of being successful, an attempt to recover life functions (ALS) must be put into action no later than 10 min after the patient's collapse. Indeed, the combination of a delayed attempt at BLS (>4 min after the event) and defibrillation >12 min later, is ineffective [44]. The survival rates among victims of a cardiac arrest who had benefited from early BLS (started by bystanders) have been analysed and compared with those of patients who had received BLS from healthcare personnel, on average 4 min later. The beneficial effect of early BLS - compared with delayed BLS - was demonstrated, particularly for cases of cardiac arrest involving ventricular fibrillation. If BLS is started early, it is more likely that the patient will be in ventricular fibrillation when the expert health personnel arrive (suggesting that early BLS prolongs the duration of the ventricular fibrillation) and therefore the patient can be defibrillated successfully. BLS carried out by bystanders results in better protection of the central nervous system. Although the differences are not statistically significant, the number of patients successfully resuscitated and admitted alive to hospital - with or without the help of bystanders - are 67 and 61%, respectively (confirming the narrow time 'window' in which the CPR manoeuvres can be carried out successfully). However, the number of victims suffering an out-of-hospital cardiac arrest who are eventually discharged from hospital is almost doubled if they had received CPR from bystanders (43%) that those who had not (22%). According to several researchers, if 20% of the adult population is trained to carry out BLS, the mortality rate from community cardiac arrest could be significantly reduced. For this reason, there is a growing need for uniform educational programmes to teach both the theoretical and practical aspects of first-aid techniques plus the manoeuvres necessary to support basic life function in the setting of wider groups of the population and the training and retraining of providers [28,45].

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Early defibrillation

The importance of early defibrillation is evident from the finding that 85% of cases of cardiac arrest occurring out of hospital - in which it was possible to have immediate and continued monitoring in the first minutes after the collapse - have a ventricular tachydysrhythmia. This drops to <60% if the arrival of healthcare personnel is delayed for 4-8 min in order to monitor the rhythm.

Ventricular tachycardia frequently evolves into ventricular fibrillation. The majority of the patients who eventually survive belong to those who remain in ventricular fibrillation until the arrival of healthcare personnel. Research, conducted at the end of the 1980s, showed how emergency medical technicians (with an adequate number of hours of training and sufficiently instructed in the use of a defibrillator) can treat patients quickly at the scene of the event (early defibrillation). These personnel can achieve higher rates of survival than for patients who are defibrillated after their arrival in hospital. In conclusion, early defibrillation is the only action that alone is more effective in patients with a cardiac arrest not caused by trauma. The implementation of the use of automatic equipment could save a greater number of patients in the future [46,47].

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Early ALS

In those situations in which CPR and defibrillation alone, even if carried out early, have not succeeded in resuscitating the patient or maintaining a spontaneous cardiac rhythm, only endotracheal intubation (to permit easier lung ventilation) and the administration of appropriate drugs will be able to restore spontaneous cardiac activity. Comparisons of various systems of emergency care show better survival rates when early defibrillation and early ALS are carried out. This is the case whether the personnel are working alone or together with others (whether or not they are trained in defibrillation) or if they are paramedical staff who are also qualified in tracheal intubation and the administration of drugs, or are doctors. Systems based only on early defibrillation by ambulance crews or only ALS by medical or paramedical staff, gave fewer positive results; indeed, the former carry out early basic CPR and defibrillation, while the latter carry out more complete, but delayed, ALS. In the case of cardiac arrest from ventricular fibrillation, early defibrillation alone by technical personnel gives similar survival rates to those obtained by the combined intervention of technical personnel and medical and paramedical staff. In the former case, many patients do not require tracheal intubation or treatment with drugs. In the latter, tracheal intubation and drugs have improved the chance of the return of a spontaneous circulation and maintaining it in the immediate post-resuscitation period.

In more technologically advanced countries, there are various different models of emergency health-care. In Europe, for example, the figure of a paramedic as portrayed in the USA does not exist. In Scandinavia and The Netherlands, a trained and qualified nurse in the ambulance normally operates the defibrillator so providing the first level intervention; if necessary, e.g. in a mobile coronary unit, the organization includes a doctor (second level of intervention). In France, Germany, Finland and, to a lesser extent, the UK and Italy, a specialist doctor in emergency care (usually an anaesthesiologist) travels in ambulances specifically equipped to provide ALS. In the USA, 'emergency systems' for the use of doctors and nurses have been abandoned because they were judged an inefficient use of professional resources. This action did not take into account the fact that paramedics perform the same task with equal efficacy. However, no system should delay the start of programmes directed towards the practice of early defibrillation by technical personnel in favour of the preferential use of paramedics or doctors in ambulances, given the long response times of the latter, which therefore produce less than satisfactory results. Defibrillation carried out by the so-called 'first responders', followed by ALS given by medical or paramedical staff, is probably the most effective method of treating ventricular fibrillation. On the other hand, where medical and paramedical staff are not readily available, the use of automatic defibrillators is the most rational choice. Therefore, a continuous programme of health education on the correct use of this equipment is necessary, excepting the legal aspects related to use of these life-support aids by unqualified personnel. Early ALS is indispensable in cases in which spontaneous circulation is not regained or not maintained after defibrillation despite monitoring of the patient and provision of ventilatory and pharmacological support in the post-resuscitation period.

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Utstein style

Surprizingly, it is extremely difficult to study cardiac arrest properly. This event usually presents unexpectedly and rarely in the presence of a doctor or expert able to give suitable first-aid. It is more common for a cardiac arrest to occur outside a protected environment. When cardiac arrest occurs in a hospital, it is usually associated with important concomitant diseases and therefore not directly comparable with the cardiac arrest that occurs outside hospital. Studies into cardiac arrest take into account epidemiological aspects such as those reported above, e.g. some risk factors are considered fixed such as age and race, or alterable such as diet and cholesterol status. Other risk factors are considered static, such as hypertension and diabetes mellitus if present for a long time. The most elusive forms are the so-called transitory risk factors, which can set off a cardiac arrest at any moment.

The collection of epidemiological data (including a glossary of terminology, e.g. definition of cardiac arrest, cardiovascular disorders, heart rate, indices of survival) is important for monitoring the various factors involved. It is essential for verifying the validity of drugs used and offering indications for the use of ALS measures and the efficacy of new therapeutic agents. Unfortunately, results obtained in one laboratory are often not repeated in another, and thus it is not easy to correlate results of different clinical trials conducted on human beings. Furthermore, to appreciate the difficulty when comparing an experimental model with a clinical one, it is sufficient to consider the efficacy of bicarbonate in the functional recovery of cardiac activity in some animal species; in man, therapeutic strategies have been revealed to be ineffective or even harmful. Thus, animal experiments cannot be considered ideal models for predicting human responses. The multiplicity of events that occur immediately before and during a cardiac arrest, and in the initial phases during the resuscitation manoeuvres and afterwards, seriously complicate the possibility of standardizing interventions, making it more difficult to interpret them correctly and to gather data that can be used for comparison. Already the difficulty of rendering the terminology uniform and standardizing interventions during a cardiac arrest in man has been described as a real Babel's tower. To clarify the situation, a number of researchers and clinicians met at Utstein Abbey in Norway (1990) to produce a standardized nomenclature and in particular to produce guidelines on the treatment of out-of-hospital cardiac arrest. During the various consensus meetings, it was possible to draw up recommendations, termed the Utstein style, that are intended to aid the collection of data relating to cardiac arrest in man and resuscitation measures. These guidelines - which focused on studies reporting information on community cardiac arrest - include a glossary of terms, a model for reporting data related to cardiac resuscitation studies so they can be compared, definitions of the times related to cardiac resuscitation itself, definitions of clinical elements and the evaluation of the outcomes collected for each patient together with suggestions for describing the emergency health systems involved. However, it is essential that there is a system that allows correct evaluation of outcomes in the long-term to permit comparisons between various clinical studies and the validity of emergency systems. Since the main aim of cardiac and cerebral resuscitation is to restore the patient's neurological function, the evaluation of long-term clinical outcome should be not only in terms of duration of life, but also in terms of the quality of life judged on the basis of overall function of the patient.

Several approaches have been made towards predicting the outcome of patients suffering coma after CPR manoeuvres. Clinical neurological examination may be complemented by the Glasgow Coma Scale (GCS) [48], with the addition of the Pittsburgh Outcome Scale [49](Table 1). This is a simple method of classifying the cerebral condition of patients who have successfully undergone cardiac and cerebral resuscitation manoeuvres. It includes two separate and parallel scales, necessary to evaluate the recovery of cerebral function, compromised by the cardiac arrest, separately from the morbidity of underlying diseases.

Table 1

Table 1

The Utstein style allows for the registration of the clinical state of the patient according to the Glasgow-Pittsburgh classification, at least in the initial period after the cardiac arrest, at the time of discharge from hospital and after 1 yr survival. Electrophysiological procedures, neuroimaging techniques [50] and biochemical tests [51] have prognostic value, but these techniques consume time and resources. Sensory-evoked potential (SEP) devices [52,53] are non-invasive, reproducible bedside techniques that may predict accurately the outcome of comatose patients during mechanical ventilation of the lungs and after CPR. SEP appear more accurate than a physician's review of clinical data. The future of clinical studies concerning community cardiac arrest lies in large-scale, multicentre studies using the same terminology and a uniform system of data collection and distribution of results. At present, the Utstein style represents a paradigm of research in the field of community related to cardiac arrest [54].

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Open questions and looking into the future

It is essential to consider some key points in the acquisition of basic knowledge about cardiac arrest with the objective of promoting further research. The 'heart pump theory' [1] has been criticized from the early 1970s. With the use of echocardiographic techniques, it was demonstrated that the heart valves are incompetent during resuscitation manoeuvres [55,56]. Furthermore, inviting the patient to cough in the first few seconds after a cardiac arrest - obviously in selected patients managed in coronary care units already undergoing haemodynamic monitoring - was sufficient to maintain an adequate cardiac output [57].

In the alternative situation defined as the 'thoracic pump theory' [57], the hypothesis is that during cardiac massage the increase in intrathoracic pressure pushes blood out of the thoracic cavity. It was thought that a generalized increase in intrathoracic pressure rather than a selective compression of the heart is the mechanism of blood flow generation during precordial compression. The increased intrathoracic pressure is transmitted to the intrathoracic vasculature, with the extrusion of blood from the intrathoracic cavity and results in a forward blood flow. Obviously, because of this controversy, the debate over whether the rate of compression during cardiac massage should be kept high or low has not been completely settled. However, the current recommendations are to perform 100 compressions a minute and this rate has been shown to be effective in maintaining the circulation. However, it is worth repeating that even when thoracic compression is carried out optimally, the amount of blood in the cerebral circulation is only about 30% of normal values.

There is great interest in perfecting defibrillation systems and their quick use by employing expert and highly qualified personnel. Progress in this technology has radically changed the approach to the patient in cardiac arrest [58-60]. Indeed, we have passed from the first generation of defibrillators (which were cumbersome, expensive and required that the operator could interpret an electrocardiogram to decide whether to give the shock or not), to automatic external defibrillators (AED) [61]. These devices contain microprocessors that can identify and interpret the main cardiac dysrhythmias and particularly ventricular fibrillation. Thus, their use is becoming widespread now that great expertise in their use is no longer necessary. The increase in the number of potential users has been shown to produce a significant improvement in the standards of care [61]. The American Heart Association (AHA) considers early defibrillation as the standard of care at the community level in first-response situations stressing the concept that 'failure of emergency personnel to have a defibrillator available during cardiac arrest is difficult to defend' [5]. It is essential to improve the therapeutic measures needed to preserve the myocardium. In addition, it is necessary to evaluate correctly post-resuscitation myocardial dysfunction and to establish the appropriate interventions necessary to restore homeostasis.

The role of vasopressor drugs is another key issue, although progress in this sphere has not been exhilarating bearing in mind that after several decades epinephrine still remains the most important drug. Redding and Pearson [62] demonstrated that i.v. administration of epinephrine was more effective than the administration of a saline solution or isoproterenol. Yakaitis and colleagues [63] confirmed the α-agonist role of epinephrine after cardiac arrest. Phenylephrine (a pure α-agonist) is as effective as epinephrine. However, even with epinephrine the number of patients who survive is far from satisfactory [64].

Various associations between epinephrine and defibrillating blocking (DF) drugs, metaraminol and phenylephrine have been studied, but the results have not been encouraging [65]. Recently, several researchers [66,67] have studied other vasopressors administered during CPR manoeuvres, including endothelin-1 and vasopressin. These seem to improve organ perfusion in animals undergoing prolonged cardiac arrest. However, vasopressin did not improve survival. Thus, the search for the ideal vasopressor is still underway. The mechanisms of ischaemic myocardial damage and the susceptibility of the cardiac myocyte to the vascular insult are equally complex. Ischaemic damage is the precursor of cellular apoptosis and therefore of irreversible myocardial damage. Targeting KATP channels in the sarcolemma and mitochondria provides a powerful way to regulate numerous metabolism-dependent cellular functions and to interfere with disease conditions associated with metabolic insult. The understanding of this process and the discovery of new pharmacological agents and mediators can improve the protection of ischaemic myocardium [68]. The use of alkaline solutions is still controversial. In fact, the administration of bicarbonate solution is no longer advised by various guidelines and is even contraindicated.

One key aspect relates to the improvement of the organization of emergency medical systems. The collection of available data must be made as uniform as possible in accordance with a methodology recognized at an international level, such as the Utstein style. Braun and other researchers showed how important considerations could be derived from the Utstein style [69,70]. Consider the response of emergency systems when they are alerted to a community cardiac arrest. The fixed reference points in time also give rise to a practically infinite series of other events and time intervals. These progress from the moment the call is received to the arrival of the health personnel at the location of the emergency. For example, consider the time that elapses when a bystander (who has witnessed the collapse of the patient) makes an alarm call, and its receipt at the operations centre of the emergency system. This interval is made up of the time taken for the bystander to decide to activate the emergency system, the time to find a telephone or a mobile telephone, the time to dial the number and the time to wait for response to the call, etc. (Fig. 1). This complex series of potentially interminable events would force researchers to make continuous references to the original Utstein definition, thus preventing their implementation. In the name of ease and speed of comprehension recommended by the Utstein style, the primary end-point using this approach is to report times of interventions after cardiac arrest and establish a set of core activities that provide the efficacy of the response to the victims of cardiac arrest. It is important to take into account ethical considerations and the decisions linked to the concept of DNR (the 'do not resuscitate' order).

Figure 1

Figure 1

There is general agreement that CPR manoeuvres must be routinely carried out in patients suffering an acute insult. In all other situations, the problem may prove very controversial, especially where the likely quality of life might be unacceptable to the patients after CPR manoeuvres [71,72]. It is therefore recommended that the decision of whether or not to initiate CPR manoeuvres (should these become necessary) be discussed, wherever possible, with the patient himself if his/her mental status is intact. In fact, a DNR decision is to be based on the likelihood of a quality of life unacceptable to the patient after CPR [73,74]. The joint British Medical Association and Royal College of Nursing Guidelines also recommend discussion with the patient when CPR is unlikely to succeed 'to secure understanding and acceptance' of the DNR decision [74]. They also provide for DNR decisions on the basis of the 'recorded and sustained wishes of a mentally competent patient' and more recently 'living wills' have received legal backing [75]. The main aim is to respect the patient's wishes, taking into account that decision. In accordance with previously mentioned factors, it is essential that an algorithm be used which allows data to be collected according to the Utstein style. This depends on (1) the aim of making available data clearer and easier to compare, (2) to exploit the concepts that underlie the dynamic process, defined as the 'chain of survival' and (3) the careful examination of the multiple aspects related to cardiac arrest. Correct information and health education is needed, particularly concerning first-aid manoeuvres and the correct training for the assistance of breathing. People must be made aware of the problem, even from school age, and master the training manoeuvres related to thoracic compression. Many volunteers, or all potential care givers in the population, must be able to activate emergency services quickly to make the aid intervention as soon as possible, and perform defibrillation when necessary. The objective is to keep the standard of intervention at a high level not only to maximize the possibility of survival, but also to recover the quality of life of a patient suffering a cardiac arrest.

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Keywords:

EDUCATION, professional; HEART ARREST, death, sudden, cardiac; RESUSCITATION, cardiopulmonary resuscitation, advanced cardiac life support, heart massage, respiration, artificial, resuscitation orders

© 2002 European Academy of Anaesthesiology