Dr Ritesh Aggarwal, Dr Omender Singh, Dr Gurpreet Singh
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The 2010 AHA Guidelines for CPR and ECC are based on the most current and comprehensive review of resuscitation literature ever published. The 2010 evidence evaluation process included 356 resuscitation experts from 29 countries who reviewed, analyzed, debated, and discussed 411 scientific evidence reviews on various topics in resuscitation and emergency cardiovascular care (1). The recommendations in the 2010 Guidelines confirm the safety and effectiveness of many approaches, acknowledge ineffectiveness of others, and introduce new treatments based on intensive evidence evaluation and consensus of experts (2). We discuss the highlights of 2010 guidelines, the key changes from the previous guidelines, and the rationale behind those changes.
CHANGES IN BASIC LIFE SUPPORT (BLS) GUIDELINES
I) The Change From "A-B-C" to "C-A-B" The newest development in the 2010 AHA Guidelines for CPR and ECC is a change in the basic life support (BLS) sequence of steps from "A-B-C" (Airway, Breathing, Chest compressions) to "C-A-B" (Chest compressions, Airway, Breathing) for adults and pediatric patients (children and infants, excluding newborns). There are multiple valid reasons for giving more emphasis to chest compressions. The highest survival rates from cardiac arrest are reported among patients of all ages with witnessed arrest and a rhythm of VF or pulseless ventricular tachycardia (VT). In these patients the critical initial elements of CPR are chest compressions and early defibrillation. Also, by changing the sequence to C-A-B, chest compressions will be initiated sooner and ventilation only minimally delayed until completion of the first cycle of chest compressions (30 compressions should be accomplished in about 18 seconds) (1,2). Having said that, a change in something as established as the A-B-C sequence would require re-education of everyone who has ever learned CPR. II) Removal of "look - listen - feel" The BLS algorithm has been simplified, and "Look, Listen and Feel" has been removed from the algorithm. Performance of these steps is inconsistent and time consuming. For this reason the revised guidelines stress immediate activation of the emergency response system and starting chest compressions for any unresponsive adult victim with no breathing or no normal breathing (ie, only gasps). III) Chest compressions In the revised guidelines, there is an increased focus on high-quality CPR. Adequate chest compressions require that compressions be provided at the appropriate depth and rate, allowing complete recoil of the chest after each compression and an emphasis on minimizing any pauses during compressions. There is an emphasis on higher "chest compression rates". The recommendation has been changed from compression rate of "approximately 100/min" to compression rate of "at least 100/min". The number of chest compressions delivered per minute during CPR is an important determinant of return of spontaneous circulation (ROSC) and survival with good neurologic function. In most studies, delivery of more compressions during resuscitation was associated with better survival, when compared to fewer compressions (3). The recommendation for chest compression depth has also been changed to "at least 2 inches (5cm)". Compressions generate critical blood flow and oxygen delivery to the heart and brain. Rescuers often do not push the chest hard enough. Studies have shown that increasing the depth of compressions is associated with increased blood flow. IV) Cricoid pressure Cricoid pressure can prevent gastric inflation and reduce the risk of regurgitation and aspiration during bag-mask ventilation, but it may also impede ventilation. Seven randomized studies showed that cricoid pressure can delay or prevent the placement of an advanced airway (e.g., endotracheal tube) and some aspiration can still occur despite application of cricoid pressure. In addition, it is difficult to appropriately train rescuers in use of the maneuver. Hence, revised guidelines do not recommend routine use of cricoid pressure in cardiac arrest. V) New "circular" ACLS algorithm (Table 1)  Before 2005, ACLS courses focused mainly on added interventions, such as manual defibrillation, drug therapy, and advanced airway management, as well as alternative and management options for special situations. Although adjunctive drug therapy and advanced airway management are still part of ACLS 2010, but the emphasis is exclusively on high quality CPR - the only thing which has consistently shown to work and improve outcomes (3). There is no definitive clinical evidence that early intubation or drug therapy improves neurologically intact survival to hospital discharge. VI) Capnography 2005 guidelines only recommended CO2 detector device to confirm endotracheal tube placement. Continuous quantitative waveform capnography is now recommended for intubated patients throughout the peri-arrest period. Moreover, its applications now include recommendations for confirming tracheal tube placement and for monitoring CPR quality and detecting return of spontaneous circulation based on end-tidal carbon dioxide (EtCO2) values. Continuous waveform capnography is the most reliable method of confirming and monitoring correct placement of an endotracheal tube. Because blood must circulate through the lungs for CO2 to be exhaled and measured, capnography can also serve as a monitor of the effectiveness of chest compressions and to detect return of spontaneous circulation. Ineffective chest compressions are associated with a low PetCO2. Falling cardiac output or re-arrest in the patient with return of spontaneous circulation also causes a decrease in PetCO2. In contrast, return of spontaneous circulation may cause an abrupt increase in PetCO2. VII) Atropine is 'out'; Adenosine is 'in' Atropine is no longer recommended for routine use in the management of pulseless electrical activity (PEA) and asystole. Evidence suggests that the routine use of atropine during PEA or asystole is unlikely to have a therapeutic benefit (4). Adenosine is recommended in the initial diagnosis and treatment of stable, undifferentiated regular, monomorphic wide-complex tachycardia. This is on the basis of new available evidence of its safety and potential efficacy. VIII) Post-cardiac arrest care Post-Cardiac Arrest Care is a new section in the revised guidelines (5). To improve survival for victims of cardiac arrest who are admitted to a hospital after return of spontaneous circulation, a comprehensive, multidisciplinary system of post-cardiac arrest care should be implemented in a consistent manner. Treatments should include cardiopulmonary and neurologic support, as well as therapeutic hypothermia and percutaneous coronary interventions (PCIs), when indicated. An electroencephalogram (EEG) for the diagnosis of seizures should be performed with prompt interpretation as soon as possible and should be monitored frequently or continuously in comatose patients after return of spontaneous circulation (ROSC). The benefits of therapeutic hypothermia have been re-emphasized, based on two recent large studies. IX) Ethical issues Until recent guidelines, no prognostic indicators had been established for patients undergoing therapeutic hypothermia. According to 2005 guidelines, there were 3 factors associated with poor outcomes:
The revised guidelines discuss ethical and withdrawal of support decisions in more details (6). In adult post-cardiac arrest patients, it is recommended that clinical neurologic signs, electrophysiologic studies, biomarkers, and imaging be performed at 3 days after cardiac arrest. On the basis of the limited available evidence, potentially reliable prognosticators of poor outcome in patients treated with therapeutic hypothermia after cardiac arrest include bilateral absence of N20 peak on somato-sensory evoked potential > 24 hours after cardiac arrest and the absence of both corneal and pupillary reflexes = 3 days after cardiac arrest. Limited available evidence also suggests that a Glasgow Coma Scale Motor Score of 2 or less at day 3 after sustained return of spontaneous circulation and presence of status epilepticus are potentially unreliable prognosticators of poor outcome in post-cardiac arrest patients treated with therapeutic hypothermia. The reliability of serum biomarkers as prognostic indicators is also limited by the relatively few patients who have been studied. Currently, there is limited evidence to guide decisions regarding withdrawal of life support. The clinician should document all available prognostic testing 72 hours after cardiac arrest treated with therapeutic hypothermia and use best clinical judgment based on this testing to make a decision to withdraw life support when appropriate.
What's new in Electrical therapies? The 1-shock protocol for VF/pulseless VT has not been changed. Over the last decade biphasic waveforms have been shown to be more effective than monophasic waveforms in cardioversion and defibrillation. However, there are no clinical data comparing one specific biphasic waveform with another (7). Whether escalating or fixed subsequent doses of energy are superior has not been tested with different waveforms. However, if higher energy levels are available in the device at hand, they may be considered if initial shocks are unsuccessful in terminating the arrhythmia. Transcutaneous pacing has also been the focus of several recent trials. Pacing is not generally recommended for patients in asystolic cardiac arrest. Three randomized controlled trials indicate no improvement in rate of admission to hospital or survival to hospital discharge when paramedics or physicians attempted pacing in patients with cardiac arrest due to asystole in the prehospital or hospital setting. However, it is reasonable for healthcare providers to be prepared to initiate pacing in patients with bradyarrhythmias in the event the heart rate does not respond to atropine or other chronotropic drugs. What's new in CPR devices? Several devices have been the focus of recent clinical trials. Use of the impedance threshold device (ITD) improved ROSC and short-term survival when used in adults with out-of-hospital cardiac arrest, but there was no significant improvement in either survival to hospital discharge or neurologically-intact survival to discharge (8). To date, no adjunct has consistently been shown to be superior to standard conventional (manual) CPR.
Table 2: Key changes in revised AHA guidelines for CPR & ECC
References
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