AHA CPR guidelines: What the 2015 BLS updates mean for EMS providers
In-depth insights into the expert recommendations for chest compressions, AED use and suspected opioid overdose
Publication of the 2015 American Heart Association (AHA) Guidelines Update for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care (ECC) represents the culmination of years of work by the most respected resuscitation researchers in the world. This publication marks the beginning of a new era in resuscitation guidelines as the AHA transitions away from a five-year periodic update to a web-based format that will allow continuous updates. This should help minimize the inconsistencies that sometimes occur when EMS medical directors update system protocols and treatment guidelines with new science between the five-year official updates made by the AHA.
This article provides some insight into a few of the most current recommendations at the basic life support (BLS) level. However, it is important to note the origin of the evidence review topics. With the 2010 publication, many lingering questions about CPR and BLS care remained. The 2015 evidence review teams prioritized those questions and selected the ones with significant new science available or those that addressed more controversial subject matters. Those prioritized questions form the basis of the 2015 update. In situations where no new evidence existed, there were no changes to the previous recommendation.
Although simplified slightly, the BLS algorithm for 2015 remains virtually identical to the 2010 version. This should help both experienced and novice rescuers learn and remember the priorities of BLS care for adult patients who suffer an out-of-hospital (OOH) cardiac arrest. However, the AHA acknowledges that actual resuscitation attempts often do not follow the linear and sequential approach presented in algorithmic form.
Choreographed EMS response
Professional resuscitation teams, especially those who are well trained and practice regularly can often accomplish many of the tasks simultaneously. Although not a new acknowledgement, it is an important reinforcement of the value of a choreographed EMS response, which is sometimes known as pit crew CPR.
The basic steps in preparation for CPR remain unchanged. Verify unresponsiveness and send someone for an AED or manual defibrillator if one is not already present on the scene. While assessing the patient for evidence of normal breathing, perform a carotid pulse check for no more than 10 seconds. Brief generalized seizures may be the first indicators of cardiac arrest in the adult patient [1,2].
After verifying pulselessness, the AHA continues to recommend immediate initiation of chest compressions following the C-A-B approach. Although there is no strong evidence that this approach improves survival compared to the traditional A-B-C model, evidence since 2010 demonstrates a reduction in time to first chest compression with the C-A-B approach [3-5]. If a defibrillator is not already on the scene or on the way, the lone rescuer should leave the patient before initiating chest compressions in order to retrieve the device.
30 compressions to 2 ventilations
The AHA continues to recommend that health care providers deliver chest compressions and assisted ventilation at a rate of 30 chest compressions for every two assisted ventilations, beginning with chest compressions.
Continuous compression approach is reasonable
However, for the first few minutes after arrival on the scene, some EMS systems deliver continuous chest compressions with no assisted ventilation [6-10]. The AHA considers this to be a reasonable approach to the management of a witnessed OOH cardiac arrest presenting in a shockable rhythm. Instead of delivering the traditional chest compression and ventilation combination, EMS agencies may deliver three intervals of 200 continuous chest compressions using passive ventilation and basic airway adjuncts. In between the chest compression intervals, the EMS providers will deliver a single defibrillation shock every two minutes, if indicated. The AHA does not recommend routine use of passive ventilation during conventional CPR.
Recommendations concerning the mechanics of CPR have changed very little. Two studies since 2010 have failed to identify an optimal hand position for performing chest compressions [11,12]. As a result, the recommended hand position remains unchanged; health care providers should compress on the lower half of the sternum in the adult patient.
Rate of compressions
The 2010 recommendations altered language from previous years to identify more accurately the minimum rate of chest compressions necessary. Those guidelines recommended a rate of at least 100 chest compressions per minute. Although no new evidence contradicts that recommendation, there is for the first time a recommendation on an upper limit of chest compression rate beyond which survival may be negatively affected. Two studies suggest survival may be improved if rescuers can keep the rate of chest compressions between 100 and 120 per minute [13,14]. In both studies, survival rates fell when rescuers compressed at a rate above 120 compressions per minute.
The AHA now recommends that rescuers attempt to compress at a rate faster than 100 but less than 120 compressions per minute. As many rescuers tend to compress at rates above 120 compressions per minute, EMS agencies should consider the use of an audio or visual device to help achieve that rate goal.
Depth of compressions
Just as important as rate is compression depth. The 2010 guidelines alter previous language to stress the need for deeper chest compressions. In those guidelines, the AHA recommended that rescuers push to a depth of at least two inches. Since publication of the 2010 guidelines, the largest study to date to address this question demonstrated that rescuers who compressed between 1.61 inches and 2.2 inches survival rates optimized survival rates . Although not necessarily affecting survival, another study suggested that compression depths greater than 2.4 inches increase the rate of patient injury . Given this new information, the AHA now recommends rescuers compress to a depth of at least two inches, but avoid compressing too deeply beyond 2.4 inches.
Since the release of the guidelines, this particular recommendation for compression depth seems to be garnering the most negative attention on EMS social media. The primary objection centers on how the AHA expects the EMS provider to compress to such a precise depth. To help, the AHA recommends incorporation of audiovisual feedback devices into the resuscitation attempt, which can provide real-time optimization of CPR performance.
Chest wall recoil
Recommendations for chest wall recoil remain unchanged despite the lack of association with clinical outcomes. Animal and pediatric studies suggest an association between incomplete chest recoil and a decrease in coronary perfusion pressure [17-19]. Despite the absence of conclusive evidence of clinical harm associated with incomplete recoil, the AHA recommends that rescuers avoid leaning on the patient’s chest during the recoil phase of chest compression.
Chest compression fraction
One term that did not exist in the 2010 guideline recommendations is chest compression fraction. Chest compression fraction is defined as the proportion of time spent performing chest compressions for patients in cardiac arrest . Researchers have demonstrated an increased likelihood of survival with higher chest compression fractions [20,21].
Obviously, one factor that influences chest compression faction is interruptions in chest compressions. More frequent interruptions in the chest compressions reduces chest compression fraction. The AHA recommends that rescuers attempt to provide chest compressions for at least 60 percent of the duration of the resuscitation attempt.
Prime the pump?
Another controversial issue is whether EMS providers arriving on the scene to find a patient in cardiac arrest should perform a period of CPR before delivering a defibrillation shock — so called priming the pump. Twelve studies utilizing various methodologies have failed to show a survival benefit related to 90 to 180 seconds of chest compressions before attempting defibrillation [22-34].
As with the 2010 guidelines, the AHA continues to recommend defibrillation as quickly as possible when the patient develops a shockable rhythm in the presence of the EMS responders. For patients who present in cardiac arrest, it is reasonable to provide chest compressions while the defibrillation pads are placed on the patient’s chest. Once the manual defibrillator or AED is ready, however, one rescuer should provide a shock. After delivering the shock, rescuers should immediately resume chest compressions instead of performing a rhythm analysis or pulse check.
Suspected opioid overdose
In situations where the patient has a pulse but is not breathing normally or is only gasping, the AHA considers the intramuscular or intranasal administration of naloxone to be reasonable when the EMS provider suspects opioid intoxication. If the suspected opioid overdose patient is in cardiac arrest, EMS providers can also administer the medication after initiating CPR. The recent approval by the Food and Drug Administration of a naloxone auto-injector for use by either bystanders or health care providers should facilitate medication delivery .
CQI for resuscitation programs
Since 2010, the AHA has recommended that resuscitation programs implement a continuous quality improvement program to monitor the quality of the resuscitation attempt then use the data gathered to improvement team performance and improve patient outcome.
Compared to previous years, the 2015 AHA guidelines represent few changes to current EMS practice. Although there are still many unanswered questions concerning basic life support, the current document provides the most scientifically sound recommendations for improving survival from cardiac arrest.
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