British Journal of Anaesthesia 1992; 69: 182-193
REVIEW ARTICLE
ADVANCES IN CARDIOPULMONARY RESUSCITATION P. J. F. BASKETT
KEY WORDS Airway. Heart: cardiopulmonary resuscitation. Ventilation.
official publication [35]. A European editor has been appointed with additional European members of the Editorial Board. Glossary of terms used in resuscitation Because resuscitation calls for a wide spectrum of skills from a plethora of specialties and organizations, each claiming a legitimate interest in its service and practice, it is perhaps not surprising to find considerable variation in the interpretation of the terms used in reporting experience. Simple terms such as response time, survival, basic and advanced life support and CPR have not hitherto been defined precisely and agreed. They may convey different meanings to different workers. As a consequence, there is confusion in interpreting results which are published or presented and comparison of systems, practice or therapy becomes impossible. Recently (1990), representatives from the AHA, ERC, the Heart and Stroke Foundation of Canada and the Australian Resuscitation Council met to establish uniform terms and definitions applying particularly to out-of-hospital resuscitation practice. Eventually a consensus was reached and the results have been published recently as the "Utstein style" [19]. Uniform data reporting The same international group also considered the question of uniform reporting of clinical experience relating to cardiac arrest. It was agreed that reporting should be based on a template indicating the sequence of events and interventions made during TABLE I. The "Ulstein style" for reporting of times of events. Optimal event times to be recorded during the pre-hospital management of cardiac arrest
Collapse—recognition First CPR by bystander Receipt of call by professionals Ambulance mobile Ambulance stops Arrival with patient First CPR by professionals First defibrillation Return of spontaneous circulation Trachea] intubation Return of spontaneous ventilation I.v. access Medications given Departure from scene Arrival at hospital
P. J. F. BASKETT, B.A., M.B., B.CH., B.A.O., F.R.c.ANAES., Depart-
ment of Anaesthesia, Frenchay Hospital, Bristol BS16 1LE.
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Cardiopulmonary resuscitation (CPR) continues to enjoy the renaissance of interest which has been stimulated jointly by an appreciation of defects in knowledge and practice [15, 52, 48] and the potential contribution of modern technology. In the past decade, national councils have been created, notably in Australia, Scandinavia and the U.K., the prime aim of which has been to analyse current knowledge and channel this into organized practice by the use of guidelines for both basic and advanced life support. Formal Advanced Cardiac Life Support Courses are to be launched shortly by the Resuscitation Council, U.K. In many ways these Councils have emulated the example set by the American Heart Association (AHA) with the National Academy of Sciences National Research Council, who have determined standards and guidelines and courses on CPR and Emergency Cardiac Care updated at regular intervals since 1966 [4]. Recently the European Resuscitation Council (ERC) has been established with representatives from virtually all of the National and European Societies of Anaesthesia, Cardiology, Intensive Care, Accident and Emergency Medicine and Immediate Care, with the goals of enhancing the standard of practice and knowledge through Europe [35]. Whilst many of the guidelines advocated may be similar to the American Standards there remain some differences which reflect European concepts. Teaching programmes for lay people and professionals need to be designed around varying styles of practice and medico-legal constraints. In the U.S.A. pre-hospital care is based generally on a two-tier response from Emergency Medical Technicians and Paramedics. In the U.K. the system is largely dependent on a single-tier response with the aim of including at least one ambulance man with paramedic training in the team. In certain areas the ambulance service has physician support from family practitioners belonging to the British Association for Immediate Care (BASIC). In several European countries pre-hospital care is provided, at least in the second-tier response, entirely by physicians who are often anaesthetists. In promulgating guidelines, allowance must be made for these varying styles of practice. Data collection using multinational standard reporting forms may reveal a preferred system or aspect of a system which can be recommended internationally. The ERC has adopted the journal Resuscitation as its
ADVANCES IN CARDIOPULMONARY RESUSCITATION TABLE II. The "Utstein style" template for CPR reporting Population served Confirmed cardiac arrests considered for resuscitation Resuscitations attempted and not attempted Aetiology: cardiac or non-cardiac Arrest witnessed or not. By whom? Initial rhythm Bystander CPR. Yes or no? By whom? Return of spontaneous circulation Admission to hospital Discharged alive or time of death in hospital Alive at one year or time of death after discharge
CLINICAL ASPECTS
Substantial changes in resuscitation practice have occurred during the past 5 years, partly from an extended knowledge and application of pathology, anatomy, physiology and pharmacology, and partly from rapid advances in technology, particularly in monitoring, defibrillators, pacing devices and automatic resuscitators. The Airway Management of the airway remains a major problem during the resuscitation process. Many deaths are still associated with pulmonary aspiration of gastric contents [31]. This is particularly likely if resuscitation attempts are prolonged and the airway remains unprotected. Except in very skilled hands positive pressure ventilation using either mouth-to-mouth or mask ventilation from a self-inflating bag or automatic resuscitator is likely to cause gastric inflation which increases the risk of regurgitation through the lifeless cardiac sphincter. The guidelines proposed by the AHA before 1985 required step-on-step rapid lung inflations at the beginning of resuscitation to counteract supposed pulmonary collapse. Undoubtedly, this often resulted in high intrapharyngeal pressures and gastric distension. Largely as a result of Melker's work [36], the guidelines were changed in 1986 to recommend only two breaths with a pause between them to allow complete exhalation before palpation of the carotid pulse and external chest compressions. Tracheal intubation
There is no doubt that orotracheal intubation with a cuffed tube remains the optimal method for guaranteeing a clear and protected airway. A major drawback is that it is not an easy technique to master
and, even when mastered, practice is required if competence is to be maintained. This presents difficulties for nurses, paramedics and indeed, many physicians who do not have regular opportunities to intubate patients' tracheas. Even the very experienced may find difficulty with certain patients who have abnormal head and neck anatomy and reduced mobility. In the U.S.A. great emphasis is placed by the American College of Surgeons Committee on Trauma in the Advanced Trauma Life Support (ATLS) Manual on the potential danger of aggravating cervical spine injury by the performance of laryngoscopy and oral intubation [3]. They have advocated the nasal route in any case of suspicion of cervical spine injury. There is little doubt that " blind " nasal intubation is a more difficult technique to master than placing the tube by the oral route using a laryngoscope. In the injured patient the possibility of aggravating cervical spine trauma to the point of causing neurological damage must be balanced against the likely delays in oxygenation of the patient incurred while nasal intubation is accomplished. It is likely that fear of medico-legal consequences may be the basis of this teaching. There is new evidence from U.S. Level I Trauma Centres that there may not be much difference in risk between the oral and nasal route provided that the operator is trained and competent [1]. Certainly the oral route is used almost exclusively in British practice and it is likely that, if aggravation of cervical injury was occurring as a result of tracheal intubation, the matter would have been highlighted in the lay and medical press and in the publications of the medical defence societies. Fibreoptic laryngoscopy may reduce the need for manipulation of the head and neck but the technique requires considerable practice, particularly in the emergency situation. In skilled hands, this method may be used to intubate the trachea when traditional methods fail but the procedure takes longer [50, 53, 54] and so leaves the ventilatory tract at greater risk from aspirated material. Although Smith and colleagues [53,54] found that fibreoptic intubation caused a greater haemodynamic response than direct laryngoscopy, Schaefer and Marsch [50] found no significant difference between the two techniques. Alternatives to tracheal intubation Because of the difficulties associated with laryngoscopy and intubation, there have been many attempts to provide a secure airway using simpler methods. These include "blind" intubation using a digital palpation technique [56] and the use of a flexible fibreoptic light wand [58]. The digital technique is not easy to master and requires the operator to have long fingers and often entails extensive movement of the atlanto-occipital and intercervical joints. The light wand can be remarkably successful but requires extensive training. Even in expert hands, failures do occur. Most promising, although not yet perfected, are the newer airways which have stemmed from the concept of the oesophageal obturator airway. The pharyngo-tracheal lumen airway (PTLA) has received considerable interest in the United States [38]
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the management of a cardiac arrest. Minimal data to be recorded for useful analysis are indicated together with optimal data for interpretation and comparison of results (table I). For comparisons of systems and practice another reporting template is applied to the population served, the geography, the number of resuscitation attempts and their aetiology, bystander involvement, initial cardiac rhythm, hospital admission and outcome (table II). The European Resuscitation Council Working Group on Research has designed a reporting form for a Cardiopulmonary Cerebral Resuscitation Registry which is suitable for multicentre, multinational use.
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184 Inflation port and valve — both cuffs inflated simultaneously
Inflation line to proximal cuff Inflation line to distal cuff \ Stylet in long tube
Distal cuff
(fig. 1) and it has been introduced into limited clinical use in the U.K. The device, which is passed blindly through the mouth, consists of two tubes. The longer tube has a distal cuff. The shorter tube, which extends just beyond a larger proximal cuff, is designed to be located in the pharynx. Normally, the longer tube passes into the oesophagus and its cuff is inflated to restrain regurgitated gastric contents from entering the airway. The proximal pharyngeal cuff is inflated to obliterate the hypopharynx. Inflation through the short rube ventilates the lungs through the larynx. Alternatively, if the long tube enters the trachea the device simply acts as a tracheal tube. The short tube then acts as a guidepath for a separate gastric tube to remove stomach contents. Clearly it is essential to know precisely if the long tube has entered the oesophagus or the trachea so that ventilation is applied to the correct tube. Normally, this is done by the usual methods of observation and auscultation of the chest wall and epigastric area and by aspiration of both tubes. The PTLA is a somewhat bulky device which may create a false passage in patients with intra-oral or pharyngeal injuries. There have been no reports of its use in a large number of patients in cardiac arrest and it remains to be seen if it proves stable during external chest compressions when the long tube is placed in the oesophagus. The laryngeal mask airway (LMA) [10, 11] has attracted enormous attention in British and, more recently, in European, American and Australian anaesthetic practice. It consists of a plain tube with a distal cuff designed to obliterate the hypopharynx and oesophageal isthmus. Ventilation through the tube inflates the lungs through the larynx if the device is placed correctly and the inflation pressure does not increase to values which cause the inspired gases to bypass the inflated cuff. Experience with anaesthetized patients has been remarkably satisfactory provided that inflation pressures do not exceed 17-20 cm H2O [5, 11]. However, as yet there are no reports of its use during external chest compressions and it is possible that the device might be dislodged by a sudden increase in intrathoracic pressure. It is also clear that the device does not
guarantee that regurgitation and aspiration of gastric contents cannot occur [11]. The incidence of incompetence is not known. ' However, the risks of a potentially imperfectly protected airway using the LMA during CPR have to be balanced against the certain risk of airway exposure to regurgitation and aspiration associated with use of an oropharyngeal airway which is the usual practice in the immediate management of a cardiac arrest. There is no doubt that house officers, nurses and paramedics can be taught easily how to place the LMA and it could be argued that this would be an improvement on current practice. Further work is required in this field. It is also possible that the LMA could be improved in design to provide even greater security. The LMA has a further potential advantage in a patient whose trachea is difficult to intubate because of anatomical deformity or limitation of movement in the head and neck. A gum elastic bougie or similar introducer can be passed into the trachea through the LMA which may then be removed allowing a tracheal tube to be passed over the bougie and placed in the trachea. The Surgical Airway The surgical airway is rarely required if an experienced and skilled anaesthetist is available immediately. The usual indication is in patients with extensive maxillofacial or larygeal injuries or, occasionally, serious anatomical deformity. Two surgical approaches to tracheal intubation are feasible: cricothyroidotomy and percutaneous surgical dilational tracheotomy. Cricothyroidotomy
Surgical cricothyroidotomy is performed with the head extended as far as possible, bearing in mind the possibility of cervical spine injury. The cricothyroid membrane is identified immediately below the thyroid cartilage. A 2-3-cm transverse incision is made in the. skin. The cricothyroid membrane is identified and incised sufficiently to accommodate a 6.0-mm tube in adults. The tube is introduced with the help of tracheal dilators under direct vision.
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Proximal cuff Distal end of short tube FIG. 1. The pharyngo-tracheal lumen airway.
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Cricothyroidotomy kits. Purpose designed cricothyroidotomy kits have been produced (for example, the Penlon Cricothyrotome, the Portex Minitrach and the Nu Trach). Each device is provided with a scalpel to incise the overlying skin. The Penlon Cricothyrotome uses a sharp flexible trochar to pierce the membrane. The trochar is then overridden by a metal cannula which is directed into the trachea. Care must be taken to ensure that the cannula can be connected to other ventilatory equipment. Misplacement of the cannula constitutes a serious hazard. In the case of the Portex Minitrach, a bougie is introduced into the trachea through an incision in the cricothyroid membrane and a 4.0-mm tracheal tube "railroaded" over the bougie. The 4.0-mm tube is too narrow for adequate ventilation over any significant time but larger size tubes up to 6.5 mm can be introduced as successive dilators. It may be difficult to locate the incision in the membrane with the bougie, especially in the gasping patient. To overcome this problem, the skin and membrane can be transfixed together with needles placed at either end of the incision. An assistant must hold the larynx steady throughout the procedure. Bleeding may occasionally present a problem in the congested, asphyxiated patient. The Nu Trach consists of an expandable trochar system which pierces the cricothyroid membrane. Successively increasing diameter dilators are introduced through the membrane until a 6.0—6.5-mm tube can be placed in the trachea. Percutaneous dilatational cricothyroidotomy. A new
approach to cricothyroidotomy has been devised by Melker [37]. An 18-gauge cannula-over-needle is inserted into the trachea through the cricothyroid membrane and directed caudally (fig. 2). Confirmation of correct placement is made by aspiration of air. The aspirating syringe and needle are removed and a flexible guidewire is passed through the cannula into the trachea. The cannula is removed
leaving the guidewire in situ. A transverse incision is made in the skin across the guidewire entry point and extended to pierce the cricothyroid membrane beneath. A dilator with a lumen is passed over the guidewire into the trachea and a 6.0-mm tube passed over the dilator to establish a reliable emergency airway permitting intermittent positive pressure or spontaneous ventilation. Percutaneous surgical dilational tracheotomy
This is another newly introduced technique which may take up to 10 min to perform [20, 44, 57]. It is therefore not generally applicable to patients in whom a cardiorespiratory arrest has occurred. It is designed primarily for the situation where tracheal intubation needs converting to tracheotomy in the Intensive Therapy or Critical Care Unit. An incision is made in the skin 1 cm below the cricothyroid membrane. The tracheal lumen is identified by aspiration of air into a syringe with a 14-gauge cannula-over-needle attached. Correct placement of the cannula may be verified using a fibreoptic laryngoscope placed in an existing tracheal tube. It is recommended that the cannula should be introduced between the first and second tracheal rings or between the cricoid and first tracheal rings. A flexible guideline is introduced into the tracheal lumen and directed caudally. Starting with an 8-French gauge cannula, successive dilators are passed into the lumen of the trachea until it is possible to introduce an 8.0-mm cuffed tracheostomy rube over the final dilator. This approach offers the possibility of a larger diameter and more permanent airway than the cricothyroidotomy approach. No serious sequelae have been reported in early series [20, 57]. Verification of Tracheal Intubation
Correct tracheal tube placement may be confirmed by several methods including digital palpation of the tube within the larynx, observation and auscultation of the chest and epigastrum, passage of a fibreoptic
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FIG. 2. Percutaneous dilatations! cricothyroidotomy.
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bronchoscope or flexible light wand or use of a carbon dioxide detector or capnograph. Of these the capnograph is particularly reliable except in cases of cardiac arrest with little carbon dioxide delivery to the lungs' and in patients pretreated with magnesium trisilicate or sodium bicarbonate to neutralize gastric acid. It does, however, provide a useful indicator of the efficacy of CPR and outcome prediction. Endtidal carbon dioxide values greater than 2 kPa carry a good prognosis and values less than 1.3 kPa carry a poor prognosis [49]. The Wee oesophageal detector is a promising, simple, inexpensive device which is undergoing further field trials [60] (fig. 3). Air is injected into the tube from a 50-ml syringe via a catheter mount. Easy aspiration confirms tracheal placement. Resistance to aspiration indicates that the tube is in the oesophagus.
robust and effective device, which is relatively inexpensive, is the Laerdal pocket mask (fig. 4). It is particularly suitable for members of the public to carry in their briefcase, handbag or car glove pocket. For hospital use, where oxygen is readily available, the addition of an oxygen inlet nipple is most suitable and enables an increased FI O J to be provided. Tube flange airways such as the Brooke airway may also be used to isolate the rescuer from the victim. They incorporate a unidirectional valve to direct the patient's exhaled air away from the rescuer and have the advantage of incorporating a short oropharyngeal airway which reduces the risk of obstruction by the tongue. Some difficulty may be encountered in achieving an airtight seal with the flange in certain patients. Self-inflating bag valve mask devices
ARTIFICIAL VENTILATION
Increasing fear of disease transmission arising from the increasing incidence of HIV infection has led to the development of protective devices designed to eliminate direct contact between the patient and the rescuer during expired air mouth-to-mouth ventilation. The simplest and least expensive devices consist of a plastic sheet to be placed over the mouth with a central unidirectional valve designed to divert the victim's exhaled gases away from the rescuer. Some devices incorporate a bite block. Two commonly available devices are the Ambu Life Key and the Laerdal Resusciade. Both are simple to use and personal experience has shown that adequate oxygen saturations can be maintained [Baskett, unpublished work]. Skin-to-skin contact is avoided but on some occasions the plastic sheet may tear away from the valve seat so that the patient's exhaled air is directed towards the rescuer. A slightly more bulky but
It is now accepted that considerable practice and skill is required to use this equipment effectively. Both ACLS and ATLS manuals [4, 8] now recommend that the self-inflating bag valve mask should be used by two rescuers—one to apply the mask and maintain correct airway alignment with two hands and the other to squeeze the bag. High inspired oxygen concentrations (FiOt > 0.6) generally cannot be achieved without an oxygen reservoir attached to the self-inflating bag. Automatic resuscitators
A variety of portable, gas-powered automatic resuscitators are now available. Some provide basic functions only, while others are more sophisticated and may be used to transport critically ill patients requiring sophisticated ventilatory patterns. Some of the available models have been assessed [12,26,39,42,43,45] and British Standards (BS 6850) have been established [13]. These devices should be time or volume cycled with minimal
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FIG. 3. The Wee oesophageal detector.
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driving gas consumption. Pressure cycled devices are unable to maintain adequate tidal volumes in patients with high airway resistance or during external chest compressions. Automatic resuscitators come into their own after the trachea has been intubated and provide more consistent ventilation during CPR than manual methods. Several mechanical automatic chest "thumpers" incorporate an automatic resuscitator programmed to provide both chest compression and pulmonary ventilation. Extracorporeal oxygenation
Although fraught with practical difficulties, extracorporeal oxygenation methods are being attempted in patients with severe cardiogenic shock, exsanguination and acute respiratory failure. Oxygenation may be achieved using an extracorporeal membrane, generally through a venous arterial shunt (ECMO) or by means of inferior vena caval balloon oxygenation. CIRCULATORY SUPPORT
Simple external chest compressions using a sequence advocated by the AHA and Resuscitation Council Guidelines continue to produce survivors from unwitnessed cardiac arrest, provided that intervention is early [23]. Early hopes arising from laboratory studies in animals suggesting that the thoracic pump effect might improve outcome after CPR have not been realized. A study of 994 patients allocated at random to conventional CPR or simultaneous compression ventilation CPR (SCV CPR) found that the conventional method produced a superior outcome [30, 51]. Debate over the "airway breathing-compression" vs "compression airwaybreathing (CAB)" sequence has now apparently resolved. The CAB sequence should be reserved for those patients suffering a witnessed arrest thought to
be caused by a primary cardiac origin. Open chest cardiac compression produces a superior output compared with external chest compressions in some patients but this is not always rewarded by an improvement in survival except during cardiothoracic surgery or in patients suffering from hypovolaemia after trauma. Cardiopulmonary bypass techniques have been adapted so that cannulation (via the femoral vessels) and circulatory support can be established within 10 min in the Emergency Department. One study [47] of patients in cardiac arrest who were unresponsive to conventional CPR produced six survivors from 36 patients who received support with cardiopulmonary bypass. Another similar study [27] suggests that patients with "out of hospital" cardiac arrest or prolonged CPR times should be excluded. This invasive method needs to be applied early if reasonable results are to be achieved [8]. Defibrillation
It is now apparent that early defibrillation is the key to survival in the majority of patients suffering from cardiac arrest caused by ventricular fibrillation. The advent of automated external defibrillators (AED) which minimize ECG signal artefact and eliminate the need for operator interpretation of the rhythm has allowed defibrillation to be applied by many non-physician groups. Any nurse or basic ambulanceman may, after a short period of training, use the semi-automatic variety which only requires application of the large adhesive electrodes and adherence to simple instructions for pressing the appropriate button to obtain rhythm analysis and shock discharge as required. The completely automatic type does not require any action by the operator other than the application of the electrodes. It may be used by other rescue personnel, air cabin crew attendants, railway station
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FIG. 4. The Laerdal pocket mask.
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conventional doses (1 mg) in human adults with cardiac arrest [34]. The large dose of adrenaline was associated with an increased initial success rate (16/28) compared with the conventional dose (6/40) but unfortunately hospital discharge rates were not significantly different. Sodium bicarbonate Sodium bicarbonate therapy during CPR may cause serious serum hyperosmolality and hyperalkalinity. Paradoxically, it may cause cellular acidosis by producing carbon dioxide which rapidly enters the cells. In contrast, sodium carbonate consumes carbon dioxide produced by bicarbonate and this has led to the suggestion that Carbicarb (a mixture of carbonate and bicarbonate) might be more appropriate for controlling acid-base balance during cardiac arrest. However, a comparative study in pigs between Carbicarb and bicarbonate did not demonstrate an improved outcome [24]. Further studies in humans would be useful to confirm or refute these results. At the present time it is recommended that sodium bicarbonate be withheld in cases of sudden cardiac arrest until 20 min has elapsed. After that interval bicarbonate should be administered, ideally in response to blood acid-base status or, if this is not available, in 50-mmol aliquots. Patients with preexisting acidosis may require earlier bicarbonate therapy, but this should be administered in response to known acid-base blood concentrations. Only 50 % correction of the base deficit should be aimed for. It should be emphasized that a near normal pH is the most important factor in acid-base balance during resuscitation and that the negative effect of metabolic acidosis may be countered by efficient carbon dioxide washout through ventilation of the lungs. The metabolic acidosis is frequently selfcorrecting after an adequate circulation has been restored.
DRUG THERAPY IN CPR
Adrenaline Adrenaline remains the most useful drug in CPR. Through its alpha adrenergic action it maintains arterial pressure to the benefit of both cerebral and coronary circulations. The beta adrenergic action may, on occasion, be helpful in restoring spontaneous rhythm in an asystolic heart but may also increase myocardial oxygen consumption in ventricular fibrillation. Accordingly, more selective alpha agonists have been assessed in comparison with adrenaline. Both noradrenaline and dopamine have been shown (in pigs) to be effective in maintaining myocardial blood flow but with no significant improvement in outcome [51]. Current guidelines [4, 18,40] recommend that adrenaline should be administered in increments of 1 mg (15 ug kg"1) in adults in ventricular fibrillation and asystole. However, in recent animal studies, Lindner [33] showed that three times this dose (45 ug kg"1) was more effective in terms of coronary perfusion pressure, myocardial blood flow and resuscitation success. An increase in the dose to 90 ug kg"1 was not rewarded by a further improvement in outcome. Lindner also compared large doses (5 mg) and
Calcium Calcium is no longer recommended in cardiac arrest except when specifically indicated in hypocalcaemia, hyperkalaemia or calcium antagonist toxicity. Nevertheless, calcium may be tried in patients with electromechanical dissociation when other drugs and treatment have proved ineffective, particularly in an otherwise healthy heart, free of ischaemic disease. Calcium antagonists improve coronary blood flow but have not been proven to be of value in cardiac arrest states. These agents have also been assessed in terms of cerebral protection, but results have been disappointing. Bretylium Bretylium tosylate is recommended for ventricular fibrillation which is refractory to a combination of lignocaine and defibrillation therapy [18]. A dose of 400 mg is recommended but it must be remembered that the effect does not develop immediately: CPR and defibrillation attempts may need to be continued for up to 30 min after i.v. administration of this agent.
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authorities, sports event rescuer marshals and, most importantly perhaps, relatives of "at risk" patients. The sequence of shocks delivered by AED in ventricular fibrillation follows recommended guidelines of the AHA and Resuscitation Council U.K. [4, 18] for adults, namely 200, 200 and 360 J. The shocks are delivered consecutively without a break for CPR unless a non-shockable rhythm is detected. After these shocks have been delivered further shocks of 360 J are given, interspersed with CPR and drug therapy. In ventricular tachycardia with unconsciousness a similar pattern of electroconversion therapy is followed by i.v. lignocaine to stabilize the ectopic focus. A potential shortcoming of automated external defibrillators is their failure to detect and respond to very fine ventricular fibrillation. Ventricular fibrillation has been defined arbitrarily as a deflection on the surface electrocardiogram of an amplitude more than 1 mm (calibration 10 mm mV"1). Deflection of less than 1 mm is classified as asystole [19]. AED cannot normally produce reduced energy shocks which may be required in children or certain medical conditions. However, some models do permit variation of the energy output by use of an override module or key which can be operated by appropriate personnel. Adgey, McKeown and Anderson have [2] reported limited experience using transoesophageal defibrillation using shocks of 50-100 J. They point out that the ECG can be monitored through oesophageal electrodes and rapid defibrillation can be achieved through the same route if defibrillation electrodes are left in situ. Implantable defibrillators/pacemakers are now available for patients at risk and it is likely that the use of these devices will increase the workload of cardiothoracic anaesthetic services.
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ADVANCES IN CARDIOPULMONARY RESUSCITATION TABLE III. Recommended procedure for drug and defibrillation therapy during cardiac arrest {Resuscitation Council U.K.). VF = Ventricular fibrillation
ECG characteristic Electromechanical dissociation Adrenaline 1 mg i.v. Treat cause if present e.g. hypovolaemia, pneumothorax, cardiac tamponade, pulmonary embolism Consider calcium
Ventricular fibrillation Defibrillate 200 J Defibrillate 200 J Defibrillate 360 J Adrenaline 1 mg i.v. Defibrillate 360 J Lignocaine 100 mg i.v. (for brisk VF) Adrenaline 1 mg i.v. Repeated defibrillations 360 J Consider bretylium 400 mg i.v.
Asystole Exclude VF Adrenaline 1 mg i.v. Atropine 2 mg i.v. Pacing (if P waves or other electrical activity present)
Recommended guidelines for drug therapy
A procedure based on the current recommended guidelines for drug therapy and defibrillation is shown in table III. Route of administration of drugs in cardiac arrest
Ideally all drugs given during cardiac arrest should be administered by a central i.v. line so that delivery into the coronary circulation is assured. However, practical difficulties with central venous cannulation, particularly in the obese and in children, may preclude this route. Peripheral i.v. administration during CPR is slow and unreliable and if this route is used the drug should be followed by a "flushing" infusion of 5 % glucose to hasten it on its way to the heart. For these reasons alternative routes have been sought. The tracheal route has been advocated for lignocaine and atropine at twice the normal i.v. doses. Unfortunately this route has not proved reliable for the administration of adrenaline [41, 46]. This may be a result of local pulmonary capillary vasoconstriction. It is emphasized that for best results the drugs should be nebulized into the lower end of the trachea using an insufflation catheter in a volume of at least 10 ml. Distribution to the pulmonary vasculature is enhanced by subsequent effective positive pressure ventilation. By contrast, the intra-osseous route has been found to be effective [28] and is gaining popularity for paediatric patients [8]. The intracardiac route is generally regarded as a last resort. There is a danger of intra-myocardial injection, intrapericardial haemorrhage and pneumothorax. Nevertheless there are many reports of the effectiveness of this route. The parasternal route is reported to be associated with fewer complications than the subxiphoid approach, particularly with practised operators [29]. ETHICAL ASPECTS OF RESUSCITATION
It should never be forgotten that death is inevitable and that the intrusive indignity of resuscitation
efforts should be reserved for those who have apparently died prematurely and have a prospect of a meaningful, contented and pain free life if resuscitation is successful. Sadly, this principle is not always achieved in modern practice for several reasons [55]. These include: The immediacy of the problem. Emergency re-
suscitation teams have no time to go into the patient's history and prognosis. Members of the ambulance service outside hospital (except in extreme circumstances such as decapitation, incineration or rigor mortis) or the nursing profession inside hospital are not qualified to certify death and therefore institute resuscitation unless specifically requested not to do so on a specific patient basis. After the resuscitation process has begun it tends to be continued until failure occurs. In some instances failure is only partial and there is a return of spontaneous circulation and ventilation but a residue of permanent cerebral damage. Failure to predict outcome. Outcome prediction is
still poor for many groups of patients and for individual patients within each group. Greater accuracy in selecting patients for resuscitation may be offered by some type of scoring system akin to the APACHE method [59]. Clearly new techniques such as extracorporeal support, which offer new chances of survival, dictate that such scoring systems are reviewed regularly in the light of current advances in practice. Doctor failure. A number of clinicians fail in their duty to identify their patients in hospital who are unsuitable for resuscitation. There are several reasons for this failure. There may be an unwillingness to accept such a weighty responsibility, a lack of foresight in anticipating that the event may occur or, regrettably, a matter of doctor pride in refusing to admit that despite all of his or her efforts in providing treatment, the patient has reached endstage disease. Fear of medico-legal consequences may lead to the doctor taking the apparently easy
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Notes Continue CPR for up to 2 min after each drug Do not interrupt CPR for more than 10 s except for defibrillation Give drugs in double doses via the tracheal rube if an i.v. cannula cannot be inserted (not for calcium)
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way out and taking no action. Discussion of such matters with the patient's relatives before the event may place an unreasonable burden on their shoulders and discussion with the patient may be distressing and inappropriate. The doctor is torn between undermining his relationship with the patient and apparently endangering his medico-legal position. Practitioners vary tremendously in their attitudes towards these ethical questions.
DISEASE TRANSMISSION DURING RESUSCITATION
Interest in the possibility of transfer of infection between patient and rescuer has heightened sharply with the increasing incidence of HIV infection in the population. No longer is this deadly infection confined to at-risk groups of male homosexuals, i.v. drug abusers and unfortunate recipients of contaminated blood product transfusions. There is now a potential that any sexually active person of either gender may be harbouring or have the disease. Cross-infection during resuscitation may arise from the following possible sources: bronchial, oropharyngeal or nasal secretions transferred during mouth-to-mouth or mouth-to-nose ventilation; direct blood-to-blood contact, most commonly arising from needle stick injuries; and cross-infection from training mannikins Mouth-to-mouth contact Diseases which can be transmitted from mouthto-mouth contact include hepatitis A and B, herpes labialis, glandular fever, meningococcal meningitis, tuberculosis, shigellosis and staphylococcal and streptococcal infections [14]. The potential for infection, however, does not appear to have been realized in practice and only sporadic cases have been reported in the literature despite many thousands of episodes of mouth-to-mouth ventilation. Over a 22-year period not a single case of transmission of disease occurred in New York firemen through mouth-to-mouth ventilation [22]. The Center for Disease Control of the United States Department of Health has published information concerning potential infection sources for HIV and hepatitis B virus (HBV). The report gives advice on precautions which should be taken if
contamination with certain body fluids or secretions is to be avoided. Blood is the most important source of these viruses but precautions should also be taken with exposure to semen, vaginal secretions and cerebrospinal, synovial, pleural, peritoneal, pericardial and amniotic fluid. Sputum, tears, sweat, urine, faeces and vomit were not considered worthy of special precautions unless they contained overt blood [17]. The Center's guidelines seem to be borne out by epidemiological studies which suggest that the possibility of salivary transmission of HIV is very remote [16, 21, 32]. In fact, there is no recorded case of HIV transmission arising as a result of mouth-tomouth ventilation. Similarly, the risk of HBV transmission is miniscule and a study has shown that hepatitis B was not passed on from a mannikin used by an infected participant [25]. Despite such reassurances, many health care workers prefer to use a protective airway shield when performing mouth-to-mouth ventilation—for aesthetic reasons if nothing else. It has been estimated that a member of the public trained in basic CPR is likely to be called upon to use his or her skills three or four times in a lifetime and that the patient is most likely to be a family member or workmate. Members of the public should, therefore, not be deterred from unprotected mouth-to-mouth resuscitation. For health care workers, however, the possibility of performing resuscitation increases enormously and it is, therefore, reasonable that protective devices such as a face mask should be universally available throughout hospitals and in the ambulance service. Blood contamination
Surgical gloves generally protect health care workers from direct contact with patient's blood during invasive aspects of advanced resuscitation procedures. Needlestick and "sharp" injuries remain a problem for which there is no current solution. The risk can be minimized by careful attention to good practice (avoiding re-sheathing of needles, etc., and provision of disposal boxes). Training mannikins
Although mannikins have not been shown to be a source of virus infection, there is a possibility of bacterial transfer from the surface or "lungs". Therefore, the mannikin should be disinfected after use according to the manufacturer's instructions. TRAINING
Training in CPR is a formidable task. The number of potential trainees in the average hospital alone is enormous and requires the services of a Resuscitation Training Officer supported by departmental instructors and guided by a multidisciplinary hospital resuscitation committee who provide guidance for update of the curriculum in the light of local audit, clinical experience and new developments. A resuscitation training room with mannikins, training aids and videos should be available in every hospital [7]. Guidelines for who should be taught the various
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Nevertheless, "do not resuscitate" policies are acknowledged in several countries in the world as being helpful to patients, relatives and hospital staff generally. Clearly, do not resuscitate orders must be applied only to individual patients and must be reviewed regularly. While taking into account the wishes of a patient and the relatives, the doctor must himself, by virtue of his training and experience, offer guidance and take responsibility for the final decision. Indeed, the decision not to resuscitate should not be confused with withdrawal of other treatment destined to make the patient comfortable and enable him to take his chance if fate so decrees. On the contrary, terminally ill patients require more generous and effective pain relief, nursing care and moral support than any other group.
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TABLE IV. Guidelines for who should be taught cardiac life support. Lay = Lay person; Rescue = Rescue services; Ambu. = ambulance service; Nurse = student nurse; WS/HN = ward sister/head nurse; SN = senior nurse in acute unit; Med. = medical student; H/intern = houseman/intern; SHO = SHO/registrar/resident; Con. = consultant/staff; Doc. = family doctor; MD = military doctor. EAR = Expired air respiration; ECC = external chest compressions; TT = tracheal tube. + = Yes, — = no Liy
Rescue
Ambu.
RGN/ RN
Nurse
WS/HN
SN
Med.
H/intern
SHO
Con.
Doc.
MD
TABLE V. Guidelines for who should be taught trauma life support. (MAST = Medical anti-shock trousers; see table IV for explanation of other terms). + = Ycs> — — no Lay Assessment' Primary _ Secondary Control of spine Basic airway control EAR ECC Oral airway t TT Cncothyrotomy Mouth-to-maik Self-inflating bag Automanc resuscitator ECG interpretation DefibriUation Automatic Manual . Control of haemorrhage MAST Peripheral i.v Central i.v Cut down i.v Arterial cannula Needle thoracostomy Cbest drain Peritoneal lavage Perkmrdlocemais Open chest cardiac massage Entonox Opkrids Ketamine Local anaenhesia
Rescue
+ + — — + + + + + + + + — — _ _ + + _ _ — ? — — — _ + + _ — — — — — _ _ — — — — _ _
Ambu.
Nurse
+ + + + + + + +
+ — + + + + + -
_
_ + + + +
+ _
( +
+ ? — — + _ _
_ _ — — + ?
_ _
+ ? ? + + _ + _ + — — — — _ _
— — + — _ _
— — + — _ _
skills involved in resuscitation are shown in tables IV and V. CPR training for members of the public is best started at school during the early teens. Adult interest can be stimulated by the media and teaching programmes should be based on a cascade arrangement with expert training programme directors who in turn each train a number of instructors who then train local leaders who then train local potential providers. It is clear that retraining is required initially at 6 months [9] although refreshment can be enhanced by cards, booklets, videos and telephone guidance during CPR [6].
WS/HN
+
SN
+ + + + + + +
-
_
? _ + _ — — — — —
+
_ — — — — — _ _ — — + — _ _
+ ? + + + + +
+ ? -1
+ .
RGN/ RN
_ + + + +
Med
H/intern
SHO
Con
Doc
MD
+ + +
+ + -H + + + +
+ + + + + + + + + + + + +
+ + + + + + + + + + ? + +
+ + + + + + + + + + + + +
+ + +
+ + + + + + + _ + + + +
+
,+
+ + +
+ + +
? _ + ? ? +
+ + ' + + + _ + + + + + — ? + — — + — — + + _ _ + _ _ _ — — _ _ _ + + + + + + _ _ + _ _ +
?
+ + + ?+ + +
+ +
+ + + + + + + + + + + + + + + + +
+
+
+
+
+
+
?
+
+ + + + + + + 4. _ + _ + + + +
+ +
+ +
+ + + + + 4+ + + + + + + +
+
+ + _ ( . + + + + + + + ? + — + — + + + _ + _ + + + _ - } . + + + + _ + + +
REFERENCES 1. Abrams K, Nolan JP, Grande CM. Trauma anesthesiology & critical care. In: Kvetan V, Gallagher JT, eds. Critical Issues in Critical Care. Philadelphia: W. B. Saunders, 1991. 2. Adgey AAJ, McKeown PP, Anderson JMcC. Cardioversion and defibrillation: the esophageal approach. In: Vincent JL, ed. Update in Intensive Care And Emergency Medicine 14.
Berlin: Springer-Verlag, 1991; 34-43. 3. American College of Surgeons. Advanced Trauma Life Support Manual. Chicago: American College of Surgeons, 1989; 46-^7. 4. American Heart Association. Standards and guidelines for cardiopulmonary resuscitation and emergency cardiac care. Journal of the American Medical Association 1986; 255:
284-303.
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Assessment Bwic tirw«y control EAR ECC Oral auway LaryngeaJ mask TT Cricothyrotomy Mouth - to-mask S
REVIEW ARTICLE
ADVANCES IN CARDIOPULMONARY RESUSCITATION P. J. F. BASKETT
KEY WORDS Airway. Heart: cardiopulmonary resuscitation. Ventilation.
official publication [35]. A European editor has been appointed with additional European members of the Editorial Board. Glossary of terms used in resuscitation Because resuscitation calls for a wide spectrum of skills from a plethora of specialties and organizations, each claiming a legitimate interest in its service and practice, it is perhaps not surprising to find considerable variation in the interpretation of the terms used in reporting experience. Simple terms such as response time, survival, basic and advanced life support and CPR have not hitherto been defined precisely and agreed. They may convey different meanings to different workers. As a consequence, there is confusion in interpreting results which are published or presented and comparison of systems, practice or therapy becomes impossible. Recently (1990), representatives from the AHA, ERC, the Heart and Stroke Foundation of Canada and the Australian Resuscitation Council met to establish uniform terms and definitions applying particularly to out-of-hospital resuscitation practice. Eventually a consensus was reached and the results have been published recently as the "Utstein style" [19]. Uniform data reporting The same international group also considered the question of uniform reporting of clinical experience relating to cardiac arrest. It was agreed that reporting should be based on a template indicating the sequence of events and interventions made during TABLE I. The "Ulstein style" for reporting of times of events. Optimal event times to be recorded during the pre-hospital management of cardiac arrest
Collapse—recognition First CPR by bystander Receipt of call by professionals Ambulance mobile Ambulance stops Arrival with patient First CPR by professionals First defibrillation Return of spontaneous circulation Trachea] intubation Return of spontaneous ventilation I.v. access Medications given Departure from scene Arrival at hospital
P. J. F. BASKETT, B.A., M.B., B.CH., B.A.O., F.R.c.ANAES., Depart-
ment of Anaesthesia, Frenchay Hospital, Bristol BS16 1LE.
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Cardiopulmonary resuscitation (CPR) continues to enjoy the renaissance of interest which has been stimulated jointly by an appreciation of defects in knowledge and practice [15, 52, 48] and the potential contribution of modern technology. In the past decade, national councils have been created, notably in Australia, Scandinavia and the U.K., the prime aim of which has been to analyse current knowledge and channel this into organized practice by the use of guidelines for both basic and advanced life support. Formal Advanced Cardiac Life Support Courses are to be launched shortly by the Resuscitation Council, U.K. In many ways these Councils have emulated the example set by the American Heart Association (AHA) with the National Academy of Sciences National Research Council, who have determined standards and guidelines and courses on CPR and Emergency Cardiac Care updated at regular intervals since 1966 [4]. Recently the European Resuscitation Council (ERC) has been established with representatives from virtually all of the National and European Societies of Anaesthesia, Cardiology, Intensive Care, Accident and Emergency Medicine and Immediate Care, with the goals of enhancing the standard of practice and knowledge through Europe [35]. Whilst many of the guidelines advocated may be similar to the American Standards there remain some differences which reflect European concepts. Teaching programmes for lay people and professionals need to be designed around varying styles of practice and medico-legal constraints. In the U.S.A. pre-hospital care is based generally on a two-tier response from Emergency Medical Technicians and Paramedics. In the U.K. the system is largely dependent on a single-tier response with the aim of including at least one ambulance man with paramedic training in the team. In certain areas the ambulance service has physician support from family practitioners belonging to the British Association for Immediate Care (BASIC). In several European countries pre-hospital care is provided, at least in the second-tier response, entirely by physicians who are often anaesthetists. In promulgating guidelines, allowance must be made for these varying styles of practice. Data collection using multinational standard reporting forms may reveal a preferred system or aspect of a system which can be recommended internationally. The ERC has adopted the journal Resuscitation as its
ADVANCES IN CARDIOPULMONARY RESUSCITATION TABLE II. The "Utstein style" template for CPR reporting Population served Confirmed cardiac arrests considered for resuscitation Resuscitations attempted and not attempted Aetiology: cardiac or non-cardiac Arrest witnessed or not. By whom? Initial rhythm Bystander CPR. Yes or no? By whom? Return of spontaneous circulation Admission to hospital Discharged alive or time of death in hospital Alive at one year or time of death after discharge
CLINICAL ASPECTS
Substantial changes in resuscitation practice have occurred during the past 5 years, partly from an extended knowledge and application of pathology, anatomy, physiology and pharmacology, and partly from rapid advances in technology, particularly in monitoring, defibrillators, pacing devices and automatic resuscitators. The Airway Management of the airway remains a major problem during the resuscitation process. Many deaths are still associated with pulmonary aspiration of gastric contents [31]. This is particularly likely if resuscitation attempts are prolonged and the airway remains unprotected. Except in very skilled hands positive pressure ventilation using either mouth-to-mouth or mask ventilation from a self-inflating bag or automatic resuscitator is likely to cause gastric inflation which increases the risk of regurgitation through the lifeless cardiac sphincter. The guidelines proposed by the AHA before 1985 required step-on-step rapid lung inflations at the beginning of resuscitation to counteract supposed pulmonary collapse. Undoubtedly, this often resulted in high intrapharyngeal pressures and gastric distension. Largely as a result of Melker's work [36], the guidelines were changed in 1986 to recommend only two breaths with a pause between them to allow complete exhalation before palpation of the carotid pulse and external chest compressions. Tracheal intubation
There is no doubt that orotracheal intubation with a cuffed tube remains the optimal method for guaranteeing a clear and protected airway. A major drawback is that it is not an easy technique to master
and, even when mastered, practice is required if competence is to be maintained. This presents difficulties for nurses, paramedics and indeed, many physicians who do not have regular opportunities to intubate patients' tracheas. Even the very experienced may find difficulty with certain patients who have abnormal head and neck anatomy and reduced mobility. In the U.S.A. great emphasis is placed by the American College of Surgeons Committee on Trauma in the Advanced Trauma Life Support (ATLS) Manual on the potential danger of aggravating cervical spine injury by the performance of laryngoscopy and oral intubation [3]. They have advocated the nasal route in any case of suspicion of cervical spine injury. There is little doubt that " blind " nasal intubation is a more difficult technique to master than placing the tube by the oral route using a laryngoscope. In the injured patient the possibility of aggravating cervical spine trauma to the point of causing neurological damage must be balanced against the likely delays in oxygenation of the patient incurred while nasal intubation is accomplished. It is likely that fear of medico-legal consequences may be the basis of this teaching. There is new evidence from U.S. Level I Trauma Centres that there may not be much difference in risk between the oral and nasal route provided that the operator is trained and competent [1]. Certainly the oral route is used almost exclusively in British practice and it is likely that, if aggravation of cervical injury was occurring as a result of tracheal intubation, the matter would have been highlighted in the lay and medical press and in the publications of the medical defence societies. Fibreoptic laryngoscopy may reduce the need for manipulation of the head and neck but the technique requires considerable practice, particularly in the emergency situation. In skilled hands, this method may be used to intubate the trachea when traditional methods fail but the procedure takes longer [50, 53, 54] and so leaves the ventilatory tract at greater risk from aspirated material. Although Smith and colleagues [53,54] found that fibreoptic intubation caused a greater haemodynamic response than direct laryngoscopy, Schaefer and Marsch [50] found no significant difference between the two techniques. Alternatives to tracheal intubation Because of the difficulties associated with laryngoscopy and intubation, there have been many attempts to provide a secure airway using simpler methods. These include "blind" intubation using a digital palpation technique [56] and the use of a flexible fibreoptic light wand [58]. The digital technique is not easy to master and requires the operator to have long fingers and often entails extensive movement of the atlanto-occipital and intercervical joints. The light wand can be remarkably successful but requires extensive training. Even in expert hands, failures do occur. Most promising, although not yet perfected, are the newer airways which have stemmed from the concept of the oesophageal obturator airway. The pharyngo-tracheal lumen airway (PTLA) has received considerable interest in the United States [38]
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the management of a cardiac arrest. Minimal data to be recorded for useful analysis are indicated together with optimal data for interpretation and comparison of results (table I). For comparisons of systems and practice another reporting template is applied to the population served, the geography, the number of resuscitation attempts and their aetiology, bystander involvement, initial cardiac rhythm, hospital admission and outcome (table II). The European Resuscitation Council Working Group on Research has designed a reporting form for a Cardiopulmonary Cerebral Resuscitation Registry which is suitable for multicentre, multinational use.
183
BRITISH JOURNAL OF ANAESTHESIA
184 Inflation port and valve — both cuffs inflated simultaneously
Inflation line to proximal cuff Inflation line to distal cuff \ Stylet in long tube
Distal cuff
(fig. 1) and it has been introduced into limited clinical use in the U.K. The device, which is passed blindly through the mouth, consists of two tubes. The longer tube has a distal cuff. The shorter tube, which extends just beyond a larger proximal cuff, is designed to be located in the pharynx. Normally, the longer tube passes into the oesophagus and its cuff is inflated to restrain regurgitated gastric contents from entering the airway. The proximal pharyngeal cuff is inflated to obliterate the hypopharynx. Inflation through the short rube ventilates the lungs through the larynx. Alternatively, if the long tube enters the trachea the device simply acts as a tracheal tube. The short tube then acts as a guidepath for a separate gastric tube to remove stomach contents. Clearly it is essential to know precisely if the long tube has entered the oesophagus or the trachea so that ventilation is applied to the correct tube. Normally, this is done by the usual methods of observation and auscultation of the chest wall and epigastric area and by aspiration of both tubes. The PTLA is a somewhat bulky device which may create a false passage in patients with intra-oral or pharyngeal injuries. There have been no reports of its use in a large number of patients in cardiac arrest and it remains to be seen if it proves stable during external chest compressions when the long tube is placed in the oesophagus. The laryngeal mask airway (LMA) [10, 11] has attracted enormous attention in British and, more recently, in European, American and Australian anaesthetic practice. It consists of a plain tube with a distal cuff designed to obliterate the hypopharynx and oesophageal isthmus. Ventilation through the tube inflates the lungs through the larynx if the device is placed correctly and the inflation pressure does not increase to values which cause the inspired gases to bypass the inflated cuff. Experience with anaesthetized patients has been remarkably satisfactory provided that inflation pressures do not exceed 17-20 cm H2O [5, 11]. However, as yet there are no reports of its use during external chest compressions and it is possible that the device might be dislodged by a sudden increase in intrathoracic pressure. It is also clear that the device does not
guarantee that regurgitation and aspiration of gastric contents cannot occur [11]. The incidence of incompetence is not known. ' However, the risks of a potentially imperfectly protected airway using the LMA during CPR have to be balanced against the certain risk of airway exposure to regurgitation and aspiration associated with use of an oropharyngeal airway which is the usual practice in the immediate management of a cardiac arrest. There is no doubt that house officers, nurses and paramedics can be taught easily how to place the LMA and it could be argued that this would be an improvement on current practice. Further work is required in this field. It is also possible that the LMA could be improved in design to provide even greater security. The LMA has a further potential advantage in a patient whose trachea is difficult to intubate because of anatomical deformity or limitation of movement in the head and neck. A gum elastic bougie or similar introducer can be passed into the trachea through the LMA which may then be removed allowing a tracheal tube to be passed over the bougie and placed in the trachea. The Surgical Airway The surgical airway is rarely required if an experienced and skilled anaesthetist is available immediately. The usual indication is in patients with extensive maxillofacial or larygeal injuries or, occasionally, serious anatomical deformity. Two surgical approaches to tracheal intubation are feasible: cricothyroidotomy and percutaneous surgical dilational tracheotomy. Cricothyroidotomy
Surgical cricothyroidotomy is performed with the head extended as far as possible, bearing in mind the possibility of cervical spine injury. The cricothyroid membrane is identified immediately below the thyroid cartilage. A 2-3-cm transverse incision is made in the. skin. The cricothyroid membrane is identified and incised sufficiently to accommodate a 6.0-mm tube in adults. The tube is introduced with the help of tracheal dilators under direct vision.
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Proximal cuff Distal end of short tube FIG. 1. The pharyngo-tracheal lumen airway.
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Cricothyroidotomy kits. Purpose designed cricothyroidotomy kits have been produced (for example, the Penlon Cricothyrotome, the Portex Minitrach and the Nu Trach). Each device is provided with a scalpel to incise the overlying skin. The Penlon Cricothyrotome uses a sharp flexible trochar to pierce the membrane. The trochar is then overridden by a metal cannula which is directed into the trachea. Care must be taken to ensure that the cannula can be connected to other ventilatory equipment. Misplacement of the cannula constitutes a serious hazard. In the case of the Portex Minitrach, a bougie is introduced into the trachea through an incision in the cricothyroid membrane and a 4.0-mm tracheal tube "railroaded" over the bougie. The 4.0-mm tube is too narrow for adequate ventilation over any significant time but larger size tubes up to 6.5 mm can be introduced as successive dilators. It may be difficult to locate the incision in the membrane with the bougie, especially in the gasping patient. To overcome this problem, the skin and membrane can be transfixed together with needles placed at either end of the incision. An assistant must hold the larynx steady throughout the procedure. Bleeding may occasionally present a problem in the congested, asphyxiated patient. The Nu Trach consists of an expandable trochar system which pierces the cricothyroid membrane. Successively increasing diameter dilators are introduced through the membrane until a 6.0—6.5-mm tube can be placed in the trachea. Percutaneous dilatational cricothyroidotomy. A new
approach to cricothyroidotomy has been devised by Melker [37]. An 18-gauge cannula-over-needle is inserted into the trachea through the cricothyroid membrane and directed caudally (fig. 2). Confirmation of correct placement is made by aspiration of air. The aspirating syringe and needle are removed and a flexible guidewire is passed through the cannula into the trachea. The cannula is removed
leaving the guidewire in situ. A transverse incision is made in the skin across the guidewire entry point and extended to pierce the cricothyroid membrane beneath. A dilator with a lumen is passed over the guidewire into the trachea and a 6.0-mm tube passed over the dilator to establish a reliable emergency airway permitting intermittent positive pressure or spontaneous ventilation. Percutaneous surgical dilational tracheotomy
This is another newly introduced technique which may take up to 10 min to perform [20, 44, 57]. It is therefore not generally applicable to patients in whom a cardiorespiratory arrest has occurred. It is designed primarily for the situation where tracheal intubation needs converting to tracheotomy in the Intensive Therapy or Critical Care Unit. An incision is made in the skin 1 cm below the cricothyroid membrane. The tracheal lumen is identified by aspiration of air into a syringe with a 14-gauge cannula-over-needle attached. Correct placement of the cannula may be verified using a fibreoptic laryngoscope placed in an existing tracheal tube. It is recommended that the cannula should be introduced between the first and second tracheal rings or between the cricoid and first tracheal rings. A flexible guideline is introduced into the tracheal lumen and directed caudally. Starting with an 8-French gauge cannula, successive dilators are passed into the lumen of the trachea until it is possible to introduce an 8.0-mm cuffed tracheostomy rube over the final dilator. This approach offers the possibility of a larger diameter and more permanent airway than the cricothyroidotomy approach. No serious sequelae have been reported in early series [20, 57]. Verification of Tracheal Intubation
Correct tracheal tube placement may be confirmed by several methods including digital palpation of the tube within the larynx, observation and auscultation of the chest and epigastrum, passage of a fibreoptic
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FIG. 2. Percutaneous dilatations! cricothyroidotomy.
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bronchoscope or flexible light wand or use of a carbon dioxide detector or capnograph. Of these the capnograph is particularly reliable except in cases of cardiac arrest with little carbon dioxide delivery to the lungs' and in patients pretreated with magnesium trisilicate or sodium bicarbonate to neutralize gastric acid. It does, however, provide a useful indicator of the efficacy of CPR and outcome prediction. Endtidal carbon dioxide values greater than 2 kPa carry a good prognosis and values less than 1.3 kPa carry a poor prognosis [49]. The Wee oesophageal detector is a promising, simple, inexpensive device which is undergoing further field trials [60] (fig. 3). Air is injected into the tube from a 50-ml syringe via a catheter mount. Easy aspiration confirms tracheal placement. Resistance to aspiration indicates that the tube is in the oesophagus.
robust and effective device, which is relatively inexpensive, is the Laerdal pocket mask (fig. 4). It is particularly suitable for members of the public to carry in their briefcase, handbag or car glove pocket. For hospital use, where oxygen is readily available, the addition of an oxygen inlet nipple is most suitable and enables an increased FI O J to be provided. Tube flange airways such as the Brooke airway may also be used to isolate the rescuer from the victim. They incorporate a unidirectional valve to direct the patient's exhaled air away from the rescuer and have the advantage of incorporating a short oropharyngeal airway which reduces the risk of obstruction by the tongue. Some difficulty may be encountered in achieving an airtight seal with the flange in certain patients. Self-inflating bag valve mask devices
ARTIFICIAL VENTILATION
Increasing fear of disease transmission arising from the increasing incidence of HIV infection has led to the development of protective devices designed to eliminate direct contact between the patient and the rescuer during expired air mouth-to-mouth ventilation. The simplest and least expensive devices consist of a plastic sheet to be placed over the mouth with a central unidirectional valve designed to divert the victim's exhaled gases away from the rescuer. Some devices incorporate a bite block. Two commonly available devices are the Ambu Life Key and the Laerdal Resusciade. Both are simple to use and personal experience has shown that adequate oxygen saturations can be maintained [Baskett, unpublished work]. Skin-to-skin contact is avoided but on some occasions the plastic sheet may tear away from the valve seat so that the patient's exhaled air is directed towards the rescuer. A slightly more bulky but
It is now accepted that considerable practice and skill is required to use this equipment effectively. Both ACLS and ATLS manuals [4, 8] now recommend that the self-inflating bag valve mask should be used by two rescuers—one to apply the mask and maintain correct airway alignment with two hands and the other to squeeze the bag. High inspired oxygen concentrations (FiOt > 0.6) generally cannot be achieved without an oxygen reservoir attached to the self-inflating bag. Automatic resuscitators
A variety of portable, gas-powered automatic resuscitators are now available. Some provide basic functions only, while others are more sophisticated and may be used to transport critically ill patients requiring sophisticated ventilatory patterns. Some of the available models have been assessed [12,26,39,42,43,45] and British Standards (BS 6850) have been established [13]. These devices should be time or volume cycled with minimal
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FIG. 3. The Wee oesophageal detector.
ADVANCES IN CARDIOPULMONARY RESUSCITATION
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driving gas consumption. Pressure cycled devices are unable to maintain adequate tidal volumes in patients with high airway resistance or during external chest compressions. Automatic resuscitators come into their own after the trachea has been intubated and provide more consistent ventilation during CPR than manual methods. Several mechanical automatic chest "thumpers" incorporate an automatic resuscitator programmed to provide both chest compression and pulmonary ventilation. Extracorporeal oxygenation
Although fraught with practical difficulties, extracorporeal oxygenation methods are being attempted in patients with severe cardiogenic shock, exsanguination and acute respiratory failure. Oxygenation may be achieved using an extracorporeal membrane, generally through a venous arterial shunt (ECMO) or by means of inferior vena caval balloon oxygenation. CIRCULATORY SUPPORT
Simple external chest compressions using a sequence advocated by the AHA and Resuscitation Council Guidelines continue to produce survivors from unwitnessed cardiac arrest, provided that intervention is early [23]. Early hopes arising from laboratory studies in animals suggesting that the thoracic pump effect might improve outcome after CPR have not been realized. A study of 994 patients allocated at random to conventional CPR or simultaneous compression ventilation CPR (SCV CPR) found that the conventional method produced a superior outcome [30, 51]. Debate over the "airway breathing-compression" vs "compression airwaybreathing (CAB)" sequence has now apparently resolved. The CAB sequence should be reserved for those patients suffering a witnessed arrest thought to
be caused by a primary cardiac origin. Open chest cardiac compression produces a superior output compared with external chest compressions in some patients but this is not always rewarded by an improvement in survival except during cardiothoracic surgery or in patients suffering from hypovolaemia after trauma. Cardiopulmonary bypass techniques have been adapted so that cannulation (via the femoral vessels) and circulatory support can be established within 10 min in the Emergency Department. One study [47] of patients in cardiac arrest who were unresponsive to conventional CPR produced six survivors from 36 patients who received support with cardiopulmonary bypass. Another similar study [27] suggests that patients with "out of hospital" cardiac arrest or prolonged CPR times should be excluded. This invasive method needs to be applied early if reasonable results are to be achieved [8]. Defibrillation
It is now apparent that early defibrillation is the key to survival in the majority of patients suffering from cardiac arrest caused by ventricular fibrillation. The advent of automated external defibrillators (AED) which minimize ECG signal artefact and eliminate the need for operator interpretation of the rhythm has allowed defibrillation to be applied by many non-physician groups. Any nurse or basic ambulanceman may, after a short period of training, use the semi-automatic variety which only requires application of the large adhesive electrodes and adherence to simple instructions for pressing the appropriate button to obtain rhythm analysis and shock discharge as required. The completely automatic type does not require any action by the operator other than the application of the electrodes. It may be used by other rescue personnel, air cabin crew attendants, railway station
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FIG. 4. The Laerdal pocket mask.
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conventional doses (1 mg) in human adults with cardiac arrest [34]. The large dose of adrenaline was associated with an increased initial success rate (16/28) compared with the conventional dose (6/40) but unfortunately hospital discharge rates were not significantly different. Sodium bicarbonate Sodium bicarbonate therapy during CPR may cause serious serum hyperosmolality and hyperalkalinity. Paradoxically, it may cause cellular acidosis by producing carbon dioxide which rapidly enters the cells. In contrast, sodium carbonate consumes carbon dioxide produced by bicarbonate and this has led to the suggestion that Carbicarb (a mixture of carbonate and bicarbonate) might be more appropriate for controlling acid-base balance during cardiac arrest. However, a comparative study in pigs between Carbicarb and bicarbonate did not demonstrate an improved outcome [24]. Further studies in humans would be useful to confirm or refute these results. At the present time it is recommended that sodium bicarbonate be withheld in cases of sudden cardiac arrest until 20 min has elapsed. After that interval bicarbonate should be administered, ideally in response to blood acid-base status or, if this is not available, in 50-mmol aliquots. Patients with preexisting acidosis may require earlier bicarbonate therapy, but this should be administered in response to known acid-base blood concentrations. Only 50 % correction of the base deficit should be aimed for. It should be emphasized that a near normal pH is the most important factor in acid-base balance during resuscitation and that the negative effect of metabolic acidosis may be countered by efficient carbon dioxide washout through ventilation of the lungs. The metabolic acidosis is frequently selfcorrecting after an adequate circulation has been restored.
DRUG THERAPY IN CPR
Adrenaline Adrenaline remains the most useful drug in CPR. Through its alpha adrenergic action it maintains arterial pressure to the benefit of both cerebral and coronary circulations. The beta adrenergic action may, on occasion, be helpful in restoring spontaneous rhythm in an asystolic heart but may also increase myocardial oxygen consumption in ventricular fibrillation. Accordingly, more selective alpha agonists have been assessed in comparison with adrenaline. Both noradrenaline and dopamine have been shown (in pigs) to be effective in maintaining myocardial blood flow but with no significant improvement in outcome [51]. Current guidelines [4, 18,40] recommend that adrenaline should be administered in increments of 1 mg (15 ug kg"1) in adults in ventricular fibrillation and asystole. However, in recent animal studies, Lindner [33] showed that three times this dose (45 ug kg"1) was more effective in terms of coronary perfusion pressure, myocardial blood flow and resuscitation success. An increase in the dose to 90 ug kg"1 was not rewarded by a further improvement in outcome. Lindner also compared large doses (5 mg) and
Calcium Calcium is no longer recommended in cardiac arrest except when specifically indicated in hypocalcaemia, hyperkalaemia or calcium antagonist toxicity. Nevertheless, calcium may be tried in patients with electromechanical dissociation when other drugs and treatment have proved ineffective, particularly in an otherwise healthy heart, free of ischaemic disease. Calcium antagonists improve coronary blood flow but have not been proven to be of value in cardiac arrest states. These agents have also been assessed in terms of cerebral protection, but results have been disappointing. Bretylium Bretylium tosylate is recommended for ventricular fibrillation which is refractory to a combination of lignocaine and defibrillation therapy [18]. A dose of 400 mg is recommended but it must be remembered that the effect does not develop immediately: CPR and defibrillation attempts may need to be continued for up to 30 min after i.v. administration of this agent.
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authorities, sports event rescuer marshals and, most importantly perhaps, relatives of "at risk" patients. The sequence of shocks delivered by AED in ventricular fibrillation follows recommended guidelines of the AHA and Resuscitation Council U.K. [4, 18] for adults, namely 200, 200 and 360 J. The shocks are delivered consecutively without a break for CPR unless a non-shockable rhythm is detected. After these shocks have been delivered further shocks of 360 J are given, interspersed with CPR and drug therapy. In ventricular tachycardia with unconsciousness a similar pattern of electroconversion therapy is followed by i.v. lignocaine to stabilize the ectopic focus. A potential shortcoming of automated external defibrillators is their failure to detect and respond to very fine ventricular fibrillation. Ventricular fibrillation has been defined arbitrarily as a deflection on the surface electrocardiogram of an amplitude more than 1 mm (calibration 10 mm mV"1). Deflection of less than 1 mm is classified as asystole [19]. AED cannot normally produce reduced energy shocks which may be required in children or certain medical conditions. However, some models do permit variation of the energy output by use of an override module or key which can be operated by appropriate personnel. Adgey, McKeown and Anderson have [2] reported limited experience using transoesophageal defibrillation using shocks of 50-100 J. They point out that the ECG can be monitored through oesophageal electrodes and rapid defibrillation can be achieved through the same route if defibrillation electrodes are left in situ. Implantable defibrillators/pacemakers are now available for patients at risk and it is likely that the use of these devices will increase the workload of cardiothoracic anaesthetic services.
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ADVANCES IN CARDIOPULMONARY RESUSCITATION TABLE III. Recommended procedure for drug and defibrillation therapy during cardiac arrest {Resuscitation Council U.K.). VF = Ventricular fibrillation
ECG characteristic Electromechanical dissociation Adrenaline 1 mg i.v. Treat cause if present e.g. hypovolaemia, pneumothorax, cardiac tamponade, pulmonary embolism Consider calcium
Ventricular fibrillation Defibrillate 200 J Defibrillate 200 J Defibrillate 360 J Adrenaline 1 mg i.v. Defibrillate 360 J Lignocaine 100 mg i.v. (for brisk VF) Adrenaline 1 mg i.v. Repeated defibrillations 360 J Consider bretylium 400 mg i.v.
Asystole Exclude VF Adrenaline 1 mg i.v. Atropine 2 mg i.v. Pacing (if P waves or other electrical activity present)
Recommended guidelines for drug therapy
A procedure based on the current recommended guidelines for drug therapy and defibrillation is shown in table III. Route of administration of drugs in cardiac arrest
Ideally all drugs given during cardiac arrest should be administered by a central i.v. line so that delivery into the coronary circulation is assured. However, practical difficulties with central venous cannulation, particularly in the obese and in children, may preclude this route. Peripheral i.v. administration during CPR is slow and unreliable and if this route is used the drug should be followed by a "flushing" infusion of 5 % glucose to hasten it on its way to the heart. For these reasons alternative routes have been sought. The tracheal route has been advocated for lignocaine and atropine at twice the normal i.v. doses. Unfortunately this route has not proved reliable for the administration of adrenaline [41, 46]. This may be a result of local pulmonary capillary vasoconstriction. It is emphasized that for best results the drugs should be nebulized into the lower end of the trachea using an insufflation catheter in a volume of at least 10 ml. Distribution to the pulmonary vasculature is enhanced by subsequent effective positive pressure ventilation. By contrast, the intra-osseous route has been found to be effective [28] and is gaining popularity for paediatric patients [8]. The intracardiac route is generally regarded as a last resort. There is a danger of intra-myocardial injection, intrapericardial haemorrhage and pneumothorax. Nevertheless there are many reports of the effectiveness of this route. The parasternal route is reported to be associated with fewer complications than the subxiphoid approach, particularly with practised operators [29]. ETHICAL ASPECTS OF RESUSCITATION
It should never be forgotten that death is inevitable and that the intrusive indignity of resuscitation
efforts should be reserved for those who have apparently died prematurely and have a prospect of a meaningful, contented and pain free life if resuscitation is successful. Sadly, this principle is not always achieved in modern practice for several reasons [55]. These include: The immediacy of the problem. Emergency re-
suscitation teams have no time to go into the patient's history and prognosis. Members of the ambulance service outside hospital (except in extreme circumstances such as decapitation, incineration or rigor mortis) or the nursing profession inside hospital are not qualified to certify death and therefore institute resuscitation unless specifically requested not to do so on a specific patient basis. After the resuscitation process has begun it tends to be continued until failure occurs. In some instances failure is only partial and there is a return of spontaneous circulation and ventilation but a residue of permanent cerebral damage. Failure to predict outcome. Outcome prediction is
still poor for many groups of patients and for individual patients within each group. Greater accuracy in selecting patients for resuscitation may be offered by some type of scoring system akin to the APACHE method [59]. Clearly new techniques such as extracorporeal support, which offer new chances of survival, dictate that such scoring systems are reviewed regularly in the light of current advances in practice. Doctor failure. A number of clinicians fail in their duty to identify their patients in hospital who are unsuitable for resuscitation. There are several reasons for this failure. There may be an unwillingness to accept such a weighty responsibility, a lack of foresight in anticipating that the event may occur or, regrettably, a matter of doctor pride in refusing to admit that despite all of his or her efforts in providing treatment, the patient has reached endstage disease. Fear of medico-legal consequences may lead to the doctor taking the apparently easy
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Notes Continue CPR for up to 2 min after each drug Do not interrupt CPR for more than 10 s except for defibrillation Give drugs in double doses via the tracheal rube if an i.v. cannula cannot be inserted (not for calcium)
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way out and taking no action. Discussion of such matters with the patient's relatives before the event may place an unreasonable burden on their shoulders and discussion with the patient may be distressing and inappropriate. The doctor is torn between undermining his relationship with the patient and apparently endangering his medico-legal position. Practitioners vary tremendously in their attitudes towards these ethical questions.
DISEASE TRANSMISSION DURING RESUSCITATION
Interest in the possibility of transfer of infection between patient and rescuer has heightened sharply with the increasing incidence of HIV infection in the population. No longer is this deadly infection confined to at-risk groups of male homosexuals, i.v. drug abusers and unfortunate recipients of contaminated blood product transfusions. There is now a potential that any sexually active person of either gender may be harbouring or have the disease. Cross-infection during resuscitation may arise from the following possible sources: bronchial, oropharyngeal or nasal secretions transferred during mouth-to-mouth or mouth-to-nose ventilation; direct blood-to-blood contact, most commonly arising from needle stick injuries; and cross-infection from training mannikins Mouth-to-mouth contact Diseases which can be transmitted from mouthto-mouth contact include hepatitis A and B, herpes labialis, glandular fever, meningococcal meningitis, tuberculosis, shigellosis and staphylococcal and streptococcal infections [14]. The potential for infection, however, does not appear to have been realized in practice and only sporadic cases have been reported in the literature despite many thousands of episodes of mouth-to-mouth ventilation. Over a 22-year period not a single case of transmission of disease occurred in New York firemen through mouth-to-mouth ventilation [22]. The Center for Disease Control of the United States Department of Health has published information concerning potential infection sources for HIV and hepatitis B virus (HBV). The report gives advice on precautions which should be taken if
contamination with certain body fluids or secretions is to be avoided. Blood is the most important source of these viruses but precautions should also be taken with exposure to semen, vaginal secretions and cerebrospinal, synovial, pleural, peritoneal, pericardial and amniotic fluid. Sputum, tears, sweat, urine, faeces and vomit were not considered worthy of special precautions unless they contained overt blood [17]. The Center's guidelines seem to be borne out by epidemiological studies which suggest that the possibility of salivary transmission of HIV is very remote [16, 21, 32]. In fact, there is no recorded case of HIV transmission arising as a result of mouth-tomouth ventilation. Similarly, the risk of HBV transmission is miniscule and a study has shown that hepatitis B was not passed on from a mannikin used by an infected participant [25]. Despite such reassurances, many health care workers prefer to use a protective airway shield when performing mouth-to-mouth ventilation—for aesthetic reasons if nothing else. It has been estimated that a member of the public trained in basic CPR is likely to be called upon to use his or her skills three or four times in a lifetime and that the patient is most likely to be a family member or workmate. Members of the public should, therefore, not be deterred from unprotected mouth-to-mouth resuscitation. For health care workers, however, the possibility of performing resuscitation increases enormously and it is, therefore, reasonable that protective devices such as a face mask should be universally available throughout hospitals and in the ambulance service. Blood contamination
Surgical gloves generally protect health care workers from direct contact with patient's blood during invasive aspects of advanced resuscitation procedures. Needlestick and "sharp" injuries remain a problem for which there is no current solution. The risk can be minimized by careful attention to good practice (avoiding re-sheathing of needles, etc., and provision of disposal boxes). Training mannikins
Although mannikins have not been shown to be a source of virus infection, there is a possibility of bacterial transfer from the surface or "lungs". Therefore, the mannikin should be disinfected after use according to the manufacturer's instructions. TRAINING
Training in CPR is a formidable task. The number of potential trainees in the average hospital alone is enormous and requires the services of a Resuscitation Training Officer supported by departmental instructors and guided by a multidisciplinary hospital resuscitation committee who provide guidance for update of the curriculum in the light of local audit, clinical experience and new developments. A resuscitation training room with mannikins, training aids and videos should be available in every hospital [7]. Guidelines for who should be taught the various
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Nevertheless, "do not resuscitate" policies are acknowledged in several countries in the world as being helpful to patients, relatives and hospital staff generally. Clearly, do not resuscitate orders must be applied only to individual patients and must be reviewed regularly. While taking into account the wishes of a patient and the relatives, the doctor must himself, by virtue of his training and experience, offer guidance and take responsibility for the final decision. Indeed, the decision not to resuscitate should not be confused with withdrawal of other treatment destined to make the patient comfortable and enable him to take his chance if fate so decrees. On the contrary, terminally ill patients require more generous and effective pain relief, nursing care and moral support than any other group.
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TABLE IV. Guidelines for who should be taught cardiac life support. Lay = Lay person; Rescue = Rescue services; Ambu. = ambulance service; Nurse = student nurse; WS/HN = ward sister/head nurse; SN = senior nurse in acute unit; Med. = medical student; H/intern = houseman/intern; SHO = SHO/registrar/resident; Con. = consultant/staff; Doc. = family doctor; MD = military doctor. EAR = Expired air respiration; ECC = external chest compressions; TT = tracheal tube. + = Yes, — = no Liy
Rescue
Ambu.
RGN/ RN
Nurse
WS/HN
SN
Med.
H/intern
SHO
Con.
Doc.
MD
TABLE V. Guidelines for who should be taught trauma life support. (MAST = Medical anti-shock trousers; see table IV for explanation of other terms). + = Ycs> — — no Lay Assessment' Primary _ Secondary Control of spine Basic airway control EAR ECC Oral airway t TT Cncothyrotomy Mouth-to-maik Self-inflating bag Automanc resuscitator ECG interpretation DefibriUation Automatic Manual . Control of haemorrhage MAST Peripheral i.v Central i.v Cut down i.v Arterial cannula Needle thoracostomy Cbest drain Peritoneal lavage Perkmrdlocemais Open chest cardiac massage Entonox Opkrids Ketamine Local anaenhesia
Rescue
+ + — — + + + + + + + + — — _ _ + + _ _ — ? — — — _ + + _ — — — — — _ _ — — — — _ _
Ambu.
Nurse
+ + + + + + + +
+ — + + + + + -
_
_ + + + +
+ _
( +
+ ? — — + _ _
_ _ — — + ?
_ _
+ ? ? + + _ + _ + — — — — _ _
— — + — _ _
— — + — _ _
skills involved in resuscitation are shown in tables IV and V. CPR training for members of the public is best started at school during the early teens. Adult interest can be stimulated by the media and teaching programmes should be based on a cascade arrangement with expert training programme directors who in turn each train a number of instructors who then train local leaders who then train local potential providers. It is clear that retraining is required initially at 6 months [9] although refreshment can be enhanced by cards, booklets, videos and telephone guidance during CPR [6].
WS/HN
+
SN
+ + + + + + +
-
_
? _ + _ — — — — —
+
_ — — — — — _ _ — — + — _ _
+ ? + + + + +
+ ? -1
+ .
RGN/ RN
_ + + + +
Med
H/intern
SHO
Con
Doc
MD
+ + +
+ + -H + + + +
+ + + + + + + + + + + + +
+ + + + + + + + + + ? + +
+ + + + + + + + + + + + +
+ + +
+ + + + + + + _ + + + +
+
,+
+ + +
+ + +
? _ + ? ? +
+ + ' + + + _ + + + + + — ? + — — + — — + + _ _ + _ _ _ — — _ _ _ + + + + + + _ _ + _ _ +
?
+ + + ?+ + +
+ +
+ + + + + + + + + + + + + + + + +
+
+
+
+
+
+
?
+
+ + + + + + + 4. _ + _ + + + +
+ +
+ +
+ + + + + 4+ + + + + + + +
+
+ + _ ( . + + + + + + + ? + — + — + + + _ + _ + + + _ - } . + + + + _ + + +
REFERENCES 1. Abrams K, Nolan JP, Grande CM. Trauma anesthesiology & critical care. In: Kvetan V, Gallagher JT, eds. Critical Issues in Critical Care. Philadelphia: W. B. Saunders, 1991. 2. Adgey AAJ, McKeown PP, Anderson JMcC. Cardioversion and defibrillation: the esophageal approach. In: Vincent JL, ed. Update in Intensive Care And Emergency Medicine 14.
Berlin: Springer-Verlag, 1991; 34-43. 3. American College of Surgeons. Advanced Trauma Life Support Manual. Chicago: American College of Surgeons, 1989; 46-^7. 4. American Heart Association. Standards and guidelines for cardiopulmonary resuscitation and emergency cardiac care. Journal of the American Medical Association 1986; 255:
284-303.
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Assessment Bwic tirw«y control EAR ECC Oral auway LaryngeaJ mask TT Cricothyrotomy Mouth - to-mask S
