INTRODUCTION — Basic life support (BLS) consists of prompt recognition of cardiac arrest, activation of emergency response systems, immediate delivery of high-quality cardiopulmonary resuscitation (CPR) and, when available, defibrillation using an automated external defibrillator (AED). Successfully completing each of these critical actions strongly predicts survival and recovery.
This topic review will discuss the critical facets of BLS in adults for clinicians as presented in the Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care (CPR-ECC Guidelines) published jointly by the International Liaison Committee on Resuscitation (ILCOR), American Heart Association (AHA), and European Resuscitation Council (ERC) [1-8]. Advanced cardiac life support (ACLS) and other related topics, such as airway management and BLS for infants and children, are presented separately. (See “Advanced cardiac life support (ACLS) in adults” and “Basic airway management in adults” and “Pediatric basic life support (BLS) for health care providers”.)
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EPIDEMIOLOGY AND SURVIVAL — Approximately 450,000 individuals suffer out-of-hospital sudden cardiac arrest (SCA) in the United States annually [9]. Roughly half of these patients have resuscitation attempted by emergency medical services (EMS).
Despite the development of cardiopulmonary resuscitation (CPR), defibrillation, and other advanced resuscitative techniques over the past 50 years, survival rates for SCA remain low. Effective delivery of BLS interventions is strongly and consistently linked to improved survival and favorable recovery after SCA. Unfortunately, multiple studies assessing both in-hospital and prehospital performance of CPR have shown that even trained health care providers consistently fail to meet BLS guidelines, emphasizing the importance to public health of dissemination and implementation of these lifesaving skills [10,11]. The epidemiology and etiology of SCA are discussed in greater detail separately. (See “Overview of sudden cardiac arrest and sudden cardiac death” and “Pathophysiology and etiology of sudden cardiac arrest”.)
RESUSCITATION GUIDELINES — The Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care (CPR-ECC Guidelines) are based upon an extensive review of the clinical and laboratory evidence performed by the International Liaison Committee on Resuscitation (ILCOR) and are published jointly by ILCOR, the American Heart Association (AHA), and the European Resuscitation Council (ERC). The CPR-ECC Guidelines and algorithms are designed to be simple, practical, and effective (algorithm 1). Updates to the guidelines are published periodically, including treatment recommendations [1,5-8,12-14]; the current version of the AHA BLS algorithm can be accessed here.
Key concepts for BLS — Important concepts and practices in the CPR-ECC Guidelines for BLS include:
●Recognize sudden cardiac arrest (SCA) as soon as possible by noting unresponsiveness or absent, gasping, or abnormal breathing. Mistakenly interpreting agonal respirations or brief convulsive activity as a reassuring sign may delay lifesaving treatments (CPR and early defibrillation) and worsen outcomes.
●A lone responder should activate emergency services first, then proceed to provide resuscitation.
●Lay rescuers should not attempt to check for a pulse. Instead, they should initiate CPR for any unconscious or unresponsive victim with abnormal or absent breathing. Performing CPR on an unresponsive person not in cardiac arrest has few adverse consequences [15]; not performing CPR on a patient who is in cardiac arrest results in a poor outcome.
●Health care providers may perform a carotid pulse check for no longer than 10 seconds prior to initiating CPR in an unresponsive patient. Again, it is far better to err on the side of initiating CPR if there is any question of pulselessness.
●Perform excellent chest compressions: “push hard, push fast” with continuous attention to the quality of chest compressions. In adults, compression-only CPR is a reasonable approach [16,17]. Lone responders or those untrained or uncomfortable providing ventilation should provide compression-only CPR [18].
●Minimize interruptions in chest compressions [14].
●Use an automated external defibrillator (AED) as soon as one is available.
Patient survival depends primarily upon prompt recognition of cardiac arrest, activation of emergency services, rapid initiation of excellent CPR, and early defibrillation [19,20].
Phases of resuscitation — Many researchers in resuscitation consider there to be three distinct phases of cardiac arrest: the electrical phase, the hemodynamic phase, and the metabolic phase [19]. The emphasis of treatment varies according to the phase.
Electrical phase — The electrical phase is defined as the first four to five minutes of cardiac arrest in patients in ventricular fibrillation (VF). Immediate defibrillation is needed to optimize survival of these patients. Performing excellent chest compressions while the defibrillator is readied provides blood flow and oxygen delivery to the heart and brain, thereby improving the chances of defibrillation and neurologic recovery, respectively [20].
Excellent chest compressions should be started immediately when SCA is suspected (delayed only for a lone rescuer to activate emergency services) and continued until the defibrillator is fully charged and ready to administer a rescue shock. Minimizing pre-shock pauses is associated with improved defibrillation success and patient outcomes [21,22]. When using an AED, the rescuer must listen and adhere to all prompts from the device. Successful defibrillation restores organized electrical activity in the heart, but there is a delay in restoration of effective ventricular contraction. Thus, CPR should be resumed immediately and continued for two minutes, followed by a pulse check, regardless of the outcome of defibrillation [23].
Hemodynamic phase — The hemodynamic or circulatory phase follows the electrical phase and consists of the period from 4 to 10 minutes after SCA, during which patients with VF-mediated SCA may remain in VF. Over time, initially coarse VF degenerates into fine VF and eventually asystole, a process that reflects myocardial energy depletion and predicts failed defibrillation. Chest compressions improve myocardial oxygen delivery and can reverse this progression and increase the chance of successful defibrillation. It remains unclear whether it is beneficial during the hemodynamic phase to delay defibrillation in order to perform two to three minutes of CPR. Randomized trials have reached inconsistent conclusions [24-26].
While it is essential to provide excellent CPR until the defibrillator is attached to the patient and charged and to resume excellent compressions immediately after the shock is delivered, we believe there is insufficient evidence of benefit to justify delaying defibrillation in order to perform chest compressions for any predetermined period. For emergency medical service (EMS) systems that advocate this approach, clinicians should consider both patient downtime and their own response time when deciding whether to postpone defibrillation to provide CPR. As an example, it would be reasonable to perform two minutes of excellent CPR prior to defibrillation for patients with an unwitnessed cardiac arrest and fine VF whose downtime is thought to exceed three to five minutes. However, it is equally reasonable to defibrillate fine VF as soon as the defibrillator is in place, without performing CPR for any prespecified period, as there is no conclusive evidence that this approach is harmful.
Metabolic phase — Treatment of the metabolic phase, defined as greater than 10 minutes of pulselessness, is primarily based upon post-resuscitative measures, including hypothermia therapy. If not quickly converted into a perfusing rhythm, patients in this phase generally do not survive. (See “Initial assessment and management of the adult post-cardiac arrest patient”.)
Recognition of cardiac arrest — Rapid recognition of cardiac arrest is the essential first step of successful resuscitation. According to the CPR-ECC Guidelines, the rescuer who witnesses a person collapse or comes across an apparently unresponsive person should check to be sure the area is safe (eg, from electrical wires) before approaching the victim and then confirm unresponsiveness by vigorously tapping or shaking the person’s shoulder and shouting “are you all right?”. If the person does not respond, the rescuer immediately calls for help, activates the emergency response system, and initiates excellent chest compressions. This sequence holds true in the in-hospital setting when a patient is discovered to be newly and unexpectedly unresponsive.
Mobile telephones are an important means for activating EMS. Many emergency dispatch centers have adopted protocols to provide instructions to untrained lay rescuers, termed dispatcher-assisted compression-only CPR, to increase bystander participation and patient survival [27].
The CPR-ECC Guidelines emphasize that even well-trained professionals have difficulty determining if pulses are present or breathing is adequate in unresponsive patients. Prolonged clinical evaluation can delay delivery of effective CPR and worsen outcomes. A knowledgeable clinician may check for a central pulse for no more than 10 seconds. The same criteria for establishing apnea are used by both lay rescuers and health care providers and should be performed in parallel with the pulse check. If the unresponsive patient is not breathing effectively, the patient should be considered apneic. When there is any uncertainty about the presence of a pulse or the adequacy of respirations in an unresponsive person, CPR should be started. The key principle is not to delay the initiation of CPR in patients who require it. The most recent version of the AHA BLS algorithm can be accessed here [1,13].
Chest compressions
Performance of excellent chest compressions — Chest compressions are the most important element of CPR [14,28-31]. Coronary and cerebral perfusion pressure and return of spontaneous circulation (ROSC) are maximized when excellent chest compressions are performed [32,33]. The mantra of the CPR-ECC Guidelines is “push hard and push fast on the center of the chest” (algorithm 1) [1,20]. Although this is easy to learn and remember, subsequent guidelines have added upper limits (no more than 120 compressions per minute) to what is considered “hard” and “fast” when performing chest compressions and emphasized the importance of allowing complete recoil of the chest wall between compressions. The most recent version of the BLS algorithm can be accessed here [1,13].
The following goals are essential for performing excellent chest compressions:
●Maintain the rate of chest compression at 100 to 120 compressions per minute [34,35].
●Compress the chest at least 5 cm (2 inches) but no more than 6 cm (2.5 inches) with each downstroke [35].
●Allow the chest to recoil completely after each downstroke (it should be easy to pull a piece of paper from between the rescuer’s hand and the patient’s chest just before the next downstroke).
●Minimize the frequency and duration of any interruptions.
To perform excellent chest compressions, the rescuer and patient must be in optimal position. Depending on the context, this may require movement of the patient or bed, adjustment of the bed’s height, or the use of a step stool so the rescuer performing chest compressions is appropriately positioned. The patient must lie on a firm surface. This may require a backboard if chest compressions are performed on a bed [36-38]. If a backboard cannot be used, the patient should be quickly moved to the floor. All efforts to deliver excellent CPR must take precedence over any advanced procedures, such as tracheal intubation or vascular access.
The rescuer places the heel of one hand in the center of the chest over the lower half of the sternum and the heel of their other hand atop the first (picture 1). The rescuer’s own chest should be directly above their hands with the elbows held in extension. This enables the rescuer to use their body weight to compress the patient’s chest rather than just the muscles of their arms, which may fatigue quickly.
It is imperative that each facet of chest compression delivery be continually reassessed and corrections made throughout the resuscitation. When multiple rescuers are present, this may be accomplished by a resuscitation team leader or through physiologic feedback such as continuous waveform capnography [39]. Multiple monitoring devices and even mobile apps have been developed that provide feedback on CPR quality [40,41]. Resuscitation teams may believe that compressions are being performed appropriately when in fact they are inadequate and cerebral perfusion is compromised, thereby reducing the chance for neurologically intact survival [42].
An inadequate rate of chest compressions reduces the likelihood of ROSC and neurologically intact survival following SCA [32,34,43,44]. Excessively rapid chest compressions can impair venous return and limit ventricular filling, resulting in worse outcomes [35,45]. The CPR-ECC Guidelines recommend a rate of 100 to 120 compressions per minute.
Clinical studies suggest that chest compressions of proper depth (approximately 5 cm) play an important role in successful resuscitation [35,42]. In addition, full chest recoil between downstrokes generates the greatest negative intrathoracic pressure, improving venous return and coronary perfusion [40,46]. According to the CPR-ECC Guidelines, rescuers are better at allowing full recoil when they receive immediate automated feedback on CPR performance and if they remove their hands slightly but completely from the chest wall at the end of each compression [41].
Inadequate chest compression rate and depth and incomplete recoil are more common when rescuers fatigue, which can begin as soon as one minute after beginning CPR [20]. The CPR-ECC Guidelines suggest that the rescuer performing chest compressions be changed every two minutes whenever more than one rescuer is present. Interruptions in chest compressions are reduced by changing the rescuer performing compressions at the two-minute interval when the compressions should cease for rhythm assessment and the patient is defibrillated if needed. However, if the rescuer is unable to perform adequate compressions, it is best to swap rescuers immediately so perfusing compressions are maintained.
Minimizing interruptions — Interruptions in chest compressions during CPR, no matter how brief, result in unacceptable declines in coronary and cerebral perfusion pressure and worse patient outcomes [14,18,21,30,43,47-51]. The most common reasons for prolonged interruptions in chest compressions are rhythm checks, changes in the clinician performing chest compressions, incorrect use of mechanical chest compression devices, and tracheal intubation [52].
If compressions are interrupted, up to one minute of continuous, excellent compressions may be required to restore sufficient perfusion pressures [53]. Two minutes of continuous CPR should be performed following any interruption [54,55]. The coordination of chest compressions and ventilation during CPR is discussed below. (See ‘Ventilations’ below.)
Rescuers must ensure that excellent chest compressions are provided with minimal interruption; rhythm analysis without compressions should only be performed at preplanned intervals (every two minutes). Such interruptions should not exceed 10 seconds, except for specific interventions, such as delivery of an AED shock. (See ‘Pulse checks and rhythm analysis’ below.)
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When using an AED, the rescuer must follow the prompts provided by the defibrillator. The AED will advise rescuers not to touch the patient while it assesses the patient’s cardiac rhythm. If the patient is in a non-shockable rhythm, the AED will instruct the rescuer to resume excellent CPR. The AED will reassess the rhythm every two minutes. If it identifies a shockable rhythm at any two-minute interval, it will charge the defibrillator and advise the rescuer to deliver a shock, followed by immediate CPR. Rescuers cannot change this sequence when using an AED (or a monitor/defibrillator in the AED mode, unless they actively change the monitor/defibrillator to manual mode).
When using a monitor/defibrillator in manual mode, rescuers should continue performing excellent chest compressions while charging the defibrillator until they are ready to deliver a single shock as indicated, and excellent compressions should resume immediately after shock delivery or after the rescuer determines that no shock is indicated. Rescuers will need to keep track of time when manually operating the monitor/defibrillator so they perform a rhythm check at two-minute intervals. Rescuers should not take extra time to assess pulse or breathing prior to defibrillation. No more than three to five seconds should elapse between stopping chest compressions and shock delivery or identification of a non-shockable rhythm. Pulse checks, if necessary, should occur during planned interruptions in compressions. If a single lay rescuer is providing CPR, excellent chest compressions should be performed continuously without ventilations. (See ‘Compression-only CPR’ below.)
Multiple studies of trained rescuers support the importance of uninterrupted chest compressions:
●One prospective study reported improved survival among out-of-hospital cardiac arrest patients treated with minimally interrupted cardiac resuscitation [23]. This study was performed as urban and rural EMS and fire department personnel in Arizona were being trained in the approach advocated by the AHA’s 2005 BLS guidelines, which were the first to emphasize continuous chest compressions with minimal interruption. Survival among patients rescued by personnel trained according to the 2005 guidelines was 5.4 percent (36 out of 668) compared with 1.8 percent (4 out of 218) among those treated according to earlier BLS guidelines (odds ratio [OR] 3.0; 95% CI 1.1-8.9).
●A retrospective observational study compared survival rates and neurologic outcomes in two groups of rural patients who sustained out-of-hospital cardiac arrest [31]. The first group was treated between 2001 and 2003 according to the 2000 CPR-ECC Guidelines (standard compressions and ventilations), while the second group was treated between 2004 and 2007 according to the 2005 Guidelines (compression-only CPR without ventilations). Among 92 patients in the first group, 18 survived, 14 (15 percent) of whom were neurologically intact. Of the 89 patients in the second group, 42 survived, 35 (39 percent) of whom were neurologically intact. Similar subsequent studies have replicated these results [49,56].
For patients receiving high-quality CPR from trained emergency medical personnel, the use of continuous chest compressions (ie, ventilations are performed without interrupting CPR) does not improve outcomes compared with delivery of 30 chest compressions followed by two rescue breaths (30:2 CPR). In a cluster-randomized trial involving 114 emergency medical service (EMS) agencies, 1129 of 12,613 patients (9 percent) treated with continuous chest compressions survived to hospital discharge compared with 1072 of 11,035 patients (9.7 percent) treated with standard 30:2 CPR (difference -0.7 percent, 95% CI -1.5 to 0.1) [55]. Neurologic outcome among survivors also did not differ significantly between groups. As noted in the accompanying editorial, the mean chest compression fraction (percentage of each minute during resuscitation when compressions were being performed) was quite high in both groups; thus, essentially neither group experienced major interruptions in CPR [57]. The CPR-ECC Guidelines suggest a chest compression fraction of at least 60 percent.
Compression-only CPR — When multiple trained personnel are present, the simultaneous performance of continuous excellent chest compressions and proper ventilation using a 30:2 compression-to-ventilation ratio is recommended by the AHA for the management of SCA [1,13,58]. The importance of ventilation increases with the duration of the arrest. (See ‘Ventilations’ below and ‘Phases of resuscitation’ above.)
However, if a sole lay rescuer is present or rescuers are reluctant to perform mouth-to-mouth ventilation, the CPR-ECC Guidelines encourage delivery of CPR using excellent chest compressions alone. The results of several randomized trials support this approach [1,13,58-60]. The CPR-ECC Guidelines further state that rescuers should not interrupt excellent chest compressions to palpate for pulses or check for ROSC and should continue CPR until an AED is ready to defibrillate, EMS personnel assume care, or the patient wakes up. Note that compression-only CPR is not recommended for children or arrest of obvious respiratory etiology (eg, drowning). (See “Pediatric basic life support (BLS) for health care providers”.)
For many would-be rescuers, the requirement to perform mouth-to-mouth ventilation is a significant barrier to the performance of CPR [11]. This reluctance may stem from fear of contracting a communicable disease, although the risk of transmission for non-respiratory diseases is extremely low [61,62]. It may also be due to anxiety about performing CPR correctly. Compression-only CPR circumvents these problems, potentially increasing the willingness of bystanders to perform CPR.
Evidence directly comparing bystander compression-only CPR with conventional CPR using a 30:2 ratio of compressions to ventilation is limited to one large observational study, which suggests improved survival when conventional CPR is performed [63]. Randomized trials of bystander CPR that have compared compression-only CPR versus conventional CPR with a 15:2 ratio have shown that compression-only CPR increases survival to hospital discharge, but evidence is lacking to show favorable neurologic outcomes with good quality of life following bystander compression-only CPR. Nevertheless, we support compression-only CPR when personnel to perform conventional CPR with a 30:2 ratio are not available. (See “Prognosis and outcomes following sudden cardiac arrest in adults”, section on ‘Chest compression-only CPR’.)
Monitoring of chest compression quality — Aside from early defibrillation of VF or polymorphic ventricular tachycardia (VT) cardiac arrest, high-quality chest compressions are the most important intervention affecting outcome. Even in the hands of experienced medical professionals, CPR quality is variable at best and frequently inadequate [35]. To ensure delivery of high-quality CPR, we recommend using monitoring and feedback devices when available.
During in-hospital cardiac arrest and out-of-hospital cardiac arrest managed by EMS, CPR quality can be monitored in several ways. In addition to close observation by other knowledgeable clinicians providing real-time correction to rescuers, three means to monitor chest compression quality include:
●Mechanical devices that provide real-time feedback of chest compression rate and depth and of adequate chest recoil
●End-tidal carbon dioxide (EtCO2) measurement, which reflects the quality of chest compressions (see “Carbon dioxide monitoring (capnography)”)
●Diastolic blood pressure measurement using invasive arterial pressure monitoring
A 2020 ILCOR systematic review found that most studies of monitoring during CPR did not find a significant association between real-time feedback and improved patient outcomes but reported no evidence of harm [15]. One randomized trial reported a 25.6 percent increase in survival to hospital discharge from in-hospital cardiac arrest with audio feedback on compression depth and recoil (54 versus 28.4 percent) [64]. An analysis of data from the AHA’s Get With The Guidelines-Resuscitation registry showed a higher likelihood of ROSC (OR 1.22, 95% CI 1.04-1.34) when CPR quality was monitored using EtCO2 or diastolic blood pressure (requiring invasive arterial pressure monitoring) [39].
A 2018 systematic review of studies of EtCO2 as a prognostic indicator following SCA found variable results, but in general, 10 mmHg or less was associated with poor outcomes while measurements above 20 mmHg were associated with higher rates of ROSC [65]. This suggests that targeting chest compressions to an EtCO2 ≥20 mmHg may be useful. The role of EtCO2 for prognosis during resuscitation of SCA is reviewed in greater detail separately. (See “Carbon dioxide monitoring (capnography)”, section on ‘Clinical applications for intubated patients’.)
Invasive arterial blood pressure monitoring may help to guide resuscitation efforts. The use of diastolic blood pressure monitoring during cardiac arrest was associated with higher ROSC, but there are inadequate human data to suggest a specific measurement threshold [39]. We do not recommend arterial blood pressure monitoring during early resuscitation unless an indwelling arterial device is already in place or response team personnel are sufficient to assign one member to insert an arterial catheter, which must be done during uninterrupted chest compressions.
Ventilations — Early after collapse, the lungs are likely to contain adequate levels of oxygen and the blood likely to be well oxygenated. At this stage, the importance of compressions supersedes ventilations [66-68]. Consequently, the initiation of excellent chest compressions is the first step to improving oxygen delivery to the tissues (algorithm 1). This is the rationale behind the compressions-airway-breathing (C-A-B) approach to SCA advocated in the CPR-ECC Guidelines [20]. The most recent version of the AHA BLS algorithm can be accessed here [13].
In some circumstances, continuing excellent compression-only CPR may be preferable to adding ventilations, especially when lay rescuers are performing the resuscitation. However, in patients whose cardiac arrest occurred in the context of antecedent hypoxia, it is likely that oxygen reserves have already been depleted, necessitating the performance of excellent standard CPR with ventilations. (See ‘Chest compressions’ above and ‘Compression-only CPR’ above.)
Ventilation becomes increasingly important as pulselessness persists. In the metabolic phase of resuscitation, clinicians must continue to ensure that ventilations do not interfere excessively with the cadence and continuity of chest compressions. The techniques used in basic airway management are discussed in greater detail separately. (See ‘Phases of resuscitation’ above and “Basic airway management in adults”.)
Proper ventilation for adults includes the following:
●Give two ventilations after every 30 compressions, discontinuing compressions during the ventilations for patients without an advanced airway [63].
●Give each ventilation over no more than one second.
●Provide only enough tidal volume to observe the chest rise (approximately 500 to 600 mL, or 6 to 7 mL/kg).
●Avoid excessive ventilation (rate or volume).
●Give one asynchronous ventilation every 8 to 10 seconds (six to eight per minute) to patients with an advanced airway (eg, supraglottic device, endotracheal tube) in place.
Although guidelines recommend 10 breaths per minute, we believe six to eight breaths are adequate in the low-flow state during cardiac resuscitation of adults. However, the key point is to avoid excessive ventilation.
Asynchronous implies ventilations need not be coordinated with chest compressions. Ventilations should be delivered in as short a period as possible, not exceeding one second per breath, while avoiding excessive ventilatory force. Only enough tidal volume to confirm initial chest rise should be given. This approach promotes both prompt resumption of compressions and improved cerebral and coronary perfusion.
In resuscitation-associated mechanical ventilation, more is not better; in fact, it is decidedly worse. Excessive ventilation, whether by high ventilatory rates or increased volumes, must be avoided. Positive-pressure ventilation raises intrathoracic pressure, which causes a decrease in venous return, pulmonary perfusion, cardiac output, and cerebral and coronary perfusion pressures [69]. Studies in animal models have found that overventilation reduces defibrillation success rates and decreases overall survival [30,54,70-72].
Despite the risk of compromised perfusion, professional rescuers routinely overventilate patients. One study of prehospital resuscitation reported that average ventilation rates during CPR were 30 per minute, while a study of in-hospital CPR revealed ventilation rates of more than 20 per minute [10,69]. It is imperative that the rate and volume of ventilations be continually reassessed and corrections made throughout the resuscitation. Resuscitation teams often believe that ventilations are being performed effectively when in fact they are not (usually due to poor bag-mask ventilation [BMV] technique), resulting in inadequate cerebral oxygen delivery and reducing the patient’s chance for a neurologically intact survival.
Defibrillation — The effectiveness of early defibrillation in patients with VF is well supported by the literature, and early defibrillation is a fundamental recommendation of the CPR-ECC Guidelines [19,73]. As soon as a defibrillator is available, providers should assess the cardiac rhythm and, when indicated, perform defibrillation as quickly as possible. With the exception of excellent CPR, there is no intervention (eg, intubation, vascular access, administration of medications) that has been found to reduce morbidity or mortality more than defibrillation in VF/VT cardiac arrest.
Defibrillator pads should be placed on dry, bare skin whenever possible. Pads should not be placed on breasts. Instead, breast tissue should be lifted away from the chest wall and the pad placed underneath. Pads may be placed over tattoos or scars, but placement over a pacemaker should be avoided.
For BLS, a single shock from an AED is followed immediately by the resumption of excellent chest compressions. For ACLS, a single shock is also recommended.
Biphasic defibrillators are preferred because of the lower energy levels needed for effective cardioversion. Biphasic defibrillators measure the impedance between the electrodes placed on the patient (figure 1) and adjust the energy delivered accordingly. Rates of first shock success are reported to be approximately 85 percent [74-76]. (See “Basic principles and technique of external electrical cardioversion and defibrillation”.)
We recommend that all defibrillations for patients in cardiac arrest be delivered at the highest available energy in adults (generally 200 J for a biphasic defibrillator and 360 J for monophasic). This approach reduces interruptions in CPR and increases the likelihood of successful defibrillation [77]. (See “Advanced cardiac life support (ACLS) in adults”, section on ‘Pulseless patient in sudden cardiac arrest’.)
Successful defibrillation requires sufficient myocardial oxygen and metabolic substrates, optimized by delivery of excellent CPR, and that the electrical current between the two defibrillator pads passes through a sufficient portion of the ventricles to successfully terminate VF/VT. Defibrillator pads are commonly placed in the anterior and lateral positions. VF/VT that is refractory to multiple defibrillation attempts may occur. In such patients, changing the location of the defibrillator pads to the anterior-posterior (AP) position or adding a second set of AP pads may improve the chances of successful defibrillation.
An unblinded, randomized controlled trial enrolled 405 patients with VF/VT out-of-hospital cardiac arrest refractory to three consecutive defibrillation attempts with anterior and lateral pad placement [78]. The trial randomized patients to continued usual care, change of pad placement to the AP position (termed “vector change”) or the addition of AP pads with double sequential defibrillation from both anterior-lateral and AP pad locations. The study was halted after fewer than 50 percent of subjects were enrolled because of low recruitment during the COVID-19 pandemic. Both vector change and double sequential defibrillation improved the primary outcome of survival to hospital discharge (21.7 versus 30.4 versus 13.3 percent, respectively). Rates of VF termination and ROSC were higher in both intervention arms compared with usual care.
Outside of clinical trials, access to multiple defibrillators for a single patient may be limited. In addition, the use of multiple defibrillators adds complexity that could detract from high-quality CPR. In the absence of any proven benefit of double sequential defibrillation compared with vector change, we recommend vector change for management of shock-refractory VF/VT.
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Controversy exists about the possible benefit of delaying defibrillation in order to perform excellent chest compressions for a predetermined period (eg, 60 to 120 seconds). This issue is discussed separately. (See ‘Hemodynamic phase’ above.)
Pulse checks and rhythm analysis — It is essential to minimize delays and interruptions in the delivery of excellent chest compressions. Therefore, cardiac rhythm analysis should only be performed during a planned interruption at the two-minute interval following a complete cycle of CPR. Even short delays in the initiation or brief interruptions in the performance of CPR can compromise cerebral and coronary perfusion pressure and decrease survival. Following any interruption, sustained chest compressions are needed to regain pre-interruption rates of blood flow. (See ‘Chest compressions’ above.)
Even among clinicians, wide variation exists in the ability to determine pulselessness accurately and efficiently [79]. Therefore, the AHA BLS guidelines recommend that untrained rescuers continue CPR without pausing for pulse checks. Health care providers must not spend more than 10 seconds checking for a pulse and should restart CPR immediately if no convincing pulse is felt. We advocate that clinicians use EtCO2 monitoring when available to determine the presence of ROSC, which reduces interruptions in CPR by obviating the need for pulse checks. (See ‘Recognition of cardiac arrest’ above and “Carbon dioxide monitoring (capnography)”, section on ‘Return of spontaneous circulation’.)
The CPR-ECC Guidelines recommend that CPR be resumed without a pulse check after any attempt at defibrillation and continued for two minutes, regardless of the resulting rhythm. Data suggest that the heart does not immediately generate effective cardiac output after defibrillation, and CPR may enhance post-defibrillation perfusion [24,76,80-82].
One observational study of 481 cases of cardiac arrest found that rhythm reanalysis, repeated shocks, and post-shock pulse checks resulted, on average, in a 29-second delay in restarting chest compressions [83]. Post-shock pulse checks were of benefit in only 1 of 50 patients.
RESUSCITATION OF SPECIAL POPULATIONS AND POST-RESUSCITATION CARE — Guidance about the resuscitation of children, pregnant patients, and other special populations and about management immediately following successful resuscitation can be found in the topics listed below:
●Resuscitation of children (see “Pediatric basic life support (BLS) for health care providers”)
●Resuscitation of pregnant patients (see “Sudden cardiac arrest and death in pregnancy”)
●Post-resuscitation management (see “Initial assessment and management of the adult post-cardiac arrest patient”)
RESUSCITATION OF PATIENTS WITH COVID-19 OR SIMILAR ILLNESS — Guidance for the performance of cardiopulmonary resuscitation (CPR) in patients with suspected or confirmed coronavirus disease 2019 (COVID-19)-related illness was first published by the American Heart Association (AHA) in 2020 and updated in 2021. Original and updated guidance emphasizes several key points, many of which apply also to other highly infectious and dangerous respiratory diseases:
●Vaccination with appropriate “booster” shots against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) offers significant protection to health care providers, including those involved in resuscitation of patients with suspected or confirmed COVID-19. (See “COVID-19: Vaccines”.)
●Personal protective equipment (PPE) is an important and effective safety measure against SARS-CoV-2 infection and should be worn according to local guidelines and availability. (See “COVID-19: General approach to infection prevention in the health care setting”.)
Systems and procedures should be in place to minimize any time delays in providing lifesaving interventions. Tasks and modifications for clinicians emphasized in the COVID 19-related guidelines include the following:
●Minimize the number of providers performing resuscitation.
●In the hospital setting, use a negative-pressure room whenever possible; keep the door to the resuscitation room closed if possible.
●A mechanical device may be used to perform chest compressions on adults and adolescents who meet minimum height and weight requirements.
●Use a high-efficiency particulate air (HEPA) filter for bag-mask ventilation (BMV) and mechanical ventilation.
COMPLICATIONS OF CPR — Injuries caused by cardiopulmonary resuscitation (CPR), especially rib and sternal fractures, are common but rarely of clinical significance. Studies demonstrating the importance of excellent chest compressions make clear that compressions of inadequate rate or depth cause significantly greater harm than any injuries sustained from high-quality chest compressions. Despite the possibility of complications, the risk of withholding possible lifesaving treatment from a patient in cardiac arrest is far exceeded by the potential benefit of CPR.
Evidence is limited, and precise rates are not known, but potential injuries from CPR may include [84-91]:
●Rib and sternal fractures (most common)
●Pneumothorax and hemothorax
●Cardiac and pulmonary contusions
●Intra-abdominal trauma, especially solid organ injury
For patients who regain spontaneous circulation, clinicians should be aware of potential complications, particularly those that may pose a threat to the patient or affect acute management, such as pneumothorax.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See “Society guideline links: Basic and advanced cardiac life support in adults”.)
SUMMARY AND RECOMMENDATIONS
●Guidelines and algorithms – The most recent version of the American Heart Association (AHA) basic life support (BLS) algorithm appears in the following graphic (algorithm 1) or can be accessed here. Important practices described in the Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care (CPR-ECC Guidelines) are summarized below.
●Chest compressions – Chest compressions are the most important element of CPR (picture 1). Interruptions in chest compressions during CPR, no matter how brief, result in unacceptable declines in coronary and cerebral perfusion pressure. The CPR mantra is “push hard and push fast (but neither too hard nor too fast) on the center of the chest.” The critical performance standards for CPR include (see ‘Chest compressions’ above):
•Maintain the rate of chest compression at 100 to 120 compressions per minute.
•Compress the chest at least 5 cm (2 inches) but no more than 6 cm (2.5 inches) with each downstroke.
•Allow the chest to recoil completely between each downstroke.
•Minimize the frequency and duration of any interruptions.
●Compression-only CPR – The appropriate use of compression-only CPR is as follows (see ‘Compression-only CPR’ above):
•If a sole lay rescuer is present or multiple lay rescuers are reluctant to perform mouth-to-mouth ventilation, the CPR-ECC Guidelines encourage the performance of CPR using chest compressions alone. Lay rescuers should not interrupt chest compressions to palpate for pulses and should continue CPR until an automated external defibrillator (AED) is ready to defibrillate, emergency medical service (EMS) personnel assume care, or the patient wakes up. Note that compression-only CPR is not recommended for children or arrest of noncardiac origin (eg, near drowning).
•When multiple trained personnel are present, the simultaneous performance of continuous excellent chest compressions and proper ventilation with a 30:2 compression-to-ventilation ratio is recommended for the management of sudden cardiac arrest (SCA).
●Ventilations – As pulselessness persists in patients with SCA, the importance of performing ventilations increases. The CPR-ECC Guidelines suggest a compression-to-ventilation ratio of 30:2. Each ventilation should be delivered over no more than one second while compressions are withheld during this time. Ventilations must not be delivered with excessive force; only enough tidal volume to confirm chest rise (6 to 7 mL/kg) should be given. Avoid excessive ventilation from high rates or increased volumes, which can compromise cardiac output. Adhere strictly to the 30:2 ratio. The effective use of a bag-mask-ventilator is a learned procedure, is best done with two people, and requires practice to maintain proficiency. (See ‘Ventilations’ above.)
●Compression-to-ventilation ratio – In adults, the CPR-ECC Guidelines recommend that CPR be performed at a ratio of 30 excellent compressions to two ventilations until an advanced airway has been placed. There is mounting evidence that early tracheal intubation results in worse outcomes; however, following placement of an advanced airway, excellent compressions are performed continuously, and asynchronous ventilations are delivered approximately six to eight times per minute. (See ‘Ventilations’ above.)
●Defibrillation – Early defibrillation is critical to the survival of patients with ventricular fibrillation (VF). The CPR-ECC Guidelines recommend a single defibrillation in all shocking sequences. In adults, we suggest defibrillation using the highest available energy (generally 200 J with a biphasic defibrillator and 360 J with a monophasic defibrillator) (Grade 2C). Compressions should not be stopped until the defibrillator has been fully charged. In VF/ventricular tachycardia (VT) arrest refractory to multiple defibrillation attempts, we advise repositioning the defibrillation pads to change the defibrillation vector (from anterior-lateral to anterior-posterior [AP] or from AP to anterior-lateral). (See ‘Defibrillation’ above.)
●Phases of resuscitation – There are three phases of SCA. The electrical phase comprises the first four to five minutes and requires immediate defibrillation preceded by excellent chest compressions as the defibrillator is quickly obtained and readied. The hemodynamic phase spans approximately minutes 4 to 10 following SCA. Patients in the hemodynamic phase benefit from excellent chest compressions to generate adequate cerebral and coronary perfusion and immediate defibrillation. The metabolic phase occurs following approximately 10 minutes of pulselessness; few patients who reach this phase survive. (See ‘Phases of resuscitation’ above.)
●Instruction – All health care providers should receive standardized training in CPR and be familiar with the operation of AEDs.
Source: https://t-tees.com
Category: WHICH
