Resuscitation guidelines 2010: a scientific consensus

Sudden cardiac death is a major killer of adults, and coronary heart disease – which kills as many as 99 000 per annum in the UK [1] – is the underlying cause in the majority of those over 40 years of age. Although in some countries, survival for patients who collapse in ventricular fibrillation (VF) is as high as 35% [2], in the UK this is not the case, and the culture of the medical community has sometimes suggested that little can or should be done for these patients. This culture is changing due to advances in techniques and better understanding of the physiological changes that occur during cardiopulmonary resuscitation (CPR), but more can be done. This October, the Resuscitation Council (Resus(UK)) published the 2010 Resuscitation Guidelines [3]. The European Resuscitation Council [4] and American Heart Association [5] published their own new guidelines on the same day, and other countries will follow suit shortly, in a demonstration of co-operation and transparency that is possibly unparalleled elsewhere in the medical scientific community. The Resus(UK) 2010 guidelines are based on the International Consensus on CPR Science with Treatment Recommendations (CoSTR) [6, 7], developed by the International Liaison Committee on Resuscitation (ILCOR), currently co-chaired by Jerry Nolan of the UK and Vinay Nadkarni of the USA. ILCOR was founded in 1992, and its membership comprises the American Heart Association, the European Resuscitation Council, the Heart and Stroke Foundation of Canada, the Australian and New Zealand Committee on Resuscitation, the Inter-American Heart Foundation, the Resuscitation Council of Asia and the Resuscitation Council of Southern Africa. It is worth outlining the consensus process to understand the scale of this collaboration, and its innate strengths and weaknesses. These are the third set of 5-yearly guidelines. The current timeline for these guidelines began in 2007 with agreement of assessment topics. In addition to revisions of previous topics, new questions were posed. Experts agreed on the worksheet questions in March 2007 and, from the beginning of 2008, more than 300 worksheets were completed, collating and evaluating all available published scientific papers on the questions posed. The worksheets were grouped into differing areas or ‘task forces’, reflecting the practical appliance of resuscitation and teaching methodologies as well as the science. The worksheets were published on the ILCOR website [8], with comments invited from both experts and non-experts. In February 2010, the worksheets were reviewed and consensus positions were agreed. Where evidence was inconclusive, an expert consensus position was agreed for national guidelines. Intuitively, one would expect that the number of differences between iterations, large at first due to elimination of inconsistencies, would reduce and plateau, reflecting only new advances. This is important for ease of implementation and the avoidance of change-fatigue in trainers and healthcare staff, and is borne out by the new guidelines. In the 2005 guidelines, the focus was on cardiac compressions and simplification of approach, to allow more effective teaching in clinical practice. This has been further developed, with a new emphasis on non-technical skills and ways to enhance and refresh learning. One welcome change in the new guidelines is that there is now a chapter on pre-hospital cardiac arrest, recognising the different aetiologies of these events, the unique challenges they pose for both the public witness and the healthcare community, and the high impact this phase has on subsequent patient outcome. Key questions before the 2010 guidelines included whether compression-only CPR is the best choice for lay bystanders, discussed recently in this journal [9] and in the Lancet [10, 11], whether pre-hospital intubation should be phased out in favour of supraglottic airway devices, and whether there should be compressions before defibrillation in non-witnessed resuscitation attempts. Therapeutic hypothermia is now established for patients with VF and ventricular tachycardia (VT), but should it be extended to non-shockable rhythms? What is the real place of drugs in resuscitation and can we more quickly predict those who are likely to survive – important decisions not only for hard-pressed managers but also for distressed relatives? In basic life support, compression depth has been increased to between 5 and 6 cm, and the use of feedback technology promoted, to assist in the delivery of high-quality compressions. This technology is available as either separate units or integrated into defibrillators. Previous studies on both humans and animals suggested that to achieve return of spontaneous circulation, coronary perfusion pressures of over 15 mmHg during chest compressions are required and that the depth previously recommended of 4–5 cm for chest compressions was inadequate [12, 13]. However, several studies [14–16] have shown that the recommended compression depth is infrequently delivered in clinical practice, and release of compressions to allow chest wall recoil – which is associated with a greater coronary perfusion pressure in animals – could be incomplete as much as 50% of the time [17, 18]. In addition to focusing on the quality of compressions, minimisation of interventions that disrupt the compression sequence is more clearly defined. Defibrillation should take a maximum period of five seconds, with charging during chest compressions. For tracheal intubation, ten seconds’ hands-off time for the passage of the tube is the only point at which compressions are paused, and pulse checks are only undertaken where there are signs suggestive of return of spontaneous circulation. The emphasis on tracheal intubation continues to decrease in favour of supraglottic airway devices. This is due to concerns about complications of intubation, long pauses in compressions without basic airway management and unrecognised oesophageal intubation, especially in those who perform the skill infrequently. Many studies have shown that use of a supraglottic device in the cardiac arrest situation is quick and easy. One study [19] suggested that there is no difference in return of spontaneous circulation or later survival using a supraglottic device; however, the device used was the Combitube, almost never used in the UK, and not included in the current guidelines. Intubation for cardiac arrest patients in an emergency is challenging. Timmerman et al. [20] showed a 16.7% incidence of difficult airway in cardiac arrest patients whose tracheas were intubated by anaesthetic-trained emergency physicians, compared with 9.8% in those for whom intubation was for medical reasons. Delaying intubation until after return of spontaneous circulation is suggested as a possible approach, although that may not be possible without expertise in anaesthetic drugs, which is not specifically addressed in the guidelines. Professionals are advised to use both primary clinical and secondary adjunct confirmation techniques to confirm the correct placement of tracheal tubes. However, with the low output produced by chest compressions, digital display of end-tidal co2 alone is not very reliable, and the presence of co2 is more positive than its absence. Silvestri et al. [21] supported the use of waveform capnography in transported patients after intubation. The current guidelines for all age groups recommend that it should be used as part of a series of tests enabling confirmation of tracheal tube placement, pointing out that it can also indicate good quality chest compressions and act as an early indicator of return of spontaneous circulation. The use and timing of drugs have been simplified, a welcome development. Adrenaline is given after the third shock at the same time as amiodarone, easier to remember than in separate cycles. Atropine, long given for asystole and slow pulseless electrical activity, is discontinued. No evidence has been found for its use in this context, or indeed for high vagal tone in a cardiac arrest. It remains for peri-arrest management. The tracheal route of drug administration is not recommended except in neonates (a second line route), following the widespread introduction of intraosseous devices. Fibrinolysis is recommended for patients presenting with a likely diagnosis of pulmonary embolus, as well as its consideration for other likely thrombotic aetiologies on a case-by-case basis. This is based on expert consensus, although the TROICA study was curtailed due to lack of a benefit trend in all-comer cardiac arrest patients [22]. There is a more detailed focus on post-resuscitation care, which is vital and might benefit from being a chapter in its own right in future guidelines. The use of standardised protocols is advocated [23–25]. Outcomes for out-of-hospital cardiac arrest survivors are extremely variable between institutions, reflecting variable philosophical approaches to this patient group and different standards of care. Individual elements of care include early re-perfusion therapy, wider use of therapeutic hypothermia, titrated oxygen therapy and moderate glucose control. Therapeutic hypothermia was incorporated into the 2005 guidelines for comatose adult survivors of out-of-hospital cardiac arrest presenting in either VF or VT [26]. Since then, some studies have shown benefit for out-of-hospital cardiac arrest survivors with all rhythms [27, 28]. Oxygen therapy is increasingly recognised as being potentially harmful, and after return of spontaneous circulation, early titration of inspired oxygen against arterial gases or oxygen saturation is recommended. Tight glucose control was thought to be beneficial, but, in fact, may lead to masked hypoglycaemic episodes and therefore the guidance on this has been relaxed. The recommendation for use of angioplasty and primary reperfusion in comatose post-cardiac arrest patients without proven ST-elevation myocardial infarction will be controversial to some, and not all hospitals will be able to deliver it. The new guidelines suggest the possible development of ‘cardiac arrest centres’, and the need for 24-h catheter laboratories could drive this [29–31]. In neonatal care, air is recommended more firmly for resuscitation of term babies. A series of studies by Vento et al. [32–35] has shown increased biochemical markers of stress for the first month of life in babies resuscitated with high concentration oxygen, as well as markers of heart and kidney damage in the first week of life. There is a shorter time to first breath and a reduction in mortality with air [36]. For all babies, the emphasis is on titrating oxygen to effect. Capnography is recommended as is the use of therapeutic hypothermia for babies with encephalopathy. New evidence here has supported previous tentative guidelines. For paediatric patients, the changes in the current guidelines are largely ones of emphasis, such as a diminution in the importance of a pulse check by healthcare providers in confirming cardiac arrest. Lay bystanders are encouraged to perform compression-only CPR (rather than none), whereas for trained rescuers, the compression:ventilation ratio of 3:1 remains. As for adults, there is increased emphasis on deeper chest compressions, to at least one-third of the chest depth: 4 cm in infants and 5 cm in children. Use of automated external defibrillator in infants is now suggested, albeit supported by case reports only; given the infrequency, the emphasis remains on the quality of CPR. Use of drugs is brought in line with the adult algorithm. There are clear advantages of an international consensus approach to the practical application of scientific principles across communities. The development of a published evidence base allows better co-ordination of research to focus strategically on areas where there is a paucity of data or ongoing controversy. New evidence supporting existing guidance can be added to worksheets as they are revised. The transparency and clarity of the process ensure that the broader medical community has the opportunity to understand the science behind their national guidelines. There are also some disadvantages. First, step-changes between iterations of guidelines inevitably mean that more than one change to ‘standard CPR’ occurs. After the 2005 guidelines, broader engagement with the scientific basis of resuscitation meant that enthusiasm was generated for participation in research by groups who had not previously been active. This is a great tribute to ILCOR, but some trials were undertaken where multiple variables acted as confounders; consequently, clear answers to important questions could not always be gained despite the enthusiasm of the investigators. Secondly, a major limitation is the timeframe for the process. The worksheets were compiled over the period 2008 to mid-2009 and therefore important papers published recently will not have been included in the CoSTR process. The meta-analysis recently published in the Lancet [10] sheds new light on the important question of whether to instruct lay bystanders actively to do only compressions pending the arrival of trained rescuers in the out-of-hospital setting. Two of the studies included that support this approach were published after consensus on science statements was finalised. Historically, where important scientific information has become available outside the cycle of guidelines, ILCOR has issued stand-alone statements. The 2010 guidelines represent the implementation of the best currently available science. There are shifts in emphasis due to increased scientific understanding, but many of the suggestions relate to broader organisational changes and will require longer implementation by resuscitation teams and acute hospitals. It is to be hoped that the UK will actively embrace these and restore its international reputation for resuscitation. No external funding and no competing interests declared.

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