Cardiopulmonary Resuscitation – An Updated Review with Guidelines

Introduction

Cardiac arrest or sudden cardiac death remains the single most common cause of death worldwide. Roughly around 300,000 patients have cardiac arrest every year in US alone. In India, it is estimated that around 7 lakh deaths occur due to cardiac arrest annually with 85% of them occurring outside hospital settings.^1,2 Only one out of every ten such patients reach the hospital, while the others die at the scene or before reaching the hospital. With proper first aid, on-site resuscitation, and timely referral with continued care, the mortality rate due to sudden cardiac arrest can be reduced by up to 60%.

History

Peter Safar, an Austrian-American anesthesiologist of Czech origin is regarded as the father of cardiopulmonary resuscitation (CPR). He demonstrated through a series of experiments on paralyzed human volunteers that the exhaled air during mouth-to-mouth rescue breathing could provide sufficient oxygenation even in apneic patients.³ Together with his colleague, James Elam, he devised the initial steps in CPR into easy-to-remember A-B-C steps – A for airway, B for breathing, and C for chest compression. He wrote the book, “ABC of Resuscitation” in 1957, which formed the basis for training in CPR.⁴ This A-B-C system for CPR training was later adopted by the American Heart Association (AHA), which established the standards of CPR training in 1973.⁴ By the 1980s, automated external defibrillators (AEDs) had become a standard addition and a D for defibrillator was added to the ABC of resuscitation. The International Liaison Committee on Resuscitation (ILCOR), constituting majority of the world’s resuscitation councils, was founded in 1992. It collects, discusses, and debates scientific evidence to review and update these guidelines constantly. As of 2020, ILCOR had presence in 192 countries globally through its associate council members.⁵ In India, the Indian Resuscitation Council (IRC), an initiative of the Indian Society of Anesthesiologists (ISA), has taken up the cause of promoting accurate and scientific resuscitation training and guidelines both to the laypeople, as well as health care professionals.⁶

Resuscitation

Cardiopulmonary resuscitation or CPR includes rescue breathing and chest compressions. Rescue breathing provides oxygen to the person’s lungs while chest compressions keep oxygen-rich blood flowing until the cardiac function and breathing are restored. The whole process of resuscitation with a stepwise algorithmic approach is often termed as life support. Two distinct but continuous forms of life support are routinely described, namely, the basic life support (BLS) and advanced cardiac life support (ACLS). Basic life support involves resuscitation at the scene without any advanced aids, gadgets, or drugs by very minimally trained personnel while ACLS involves resuscitation by trained personnel often with advanced medical aid. Both are patented courses offered by the AHA but followed throughout the world with very minor, subtle modifications or endorsements by the respective resuscitation councils. In India, BLS and ACLS are called basic cardiopulmonary life support (BCLS) and comprehensive cardiovascular life support (CCLS), respectively – both developed and promoted by IRC.

What is cardiac arrest?

Sudden cessation of cardiac function is called cardiac arrest. It is usually caused by rapid or chaotic electrical impulses in the heart, resulting in its abrupt cessation. The most common cause of cardiac arrest is myocardial infarction. Quite often, laypeople confuse between cardiac arrest, which results from erratic electrical impulses, and heart attack, which is an ischemic problem. Therefore, the difference between the two should be clearly emphasized during training. Of note, the most common cause of cardiac arrest is ischemic in origin.

A person is said to be in cardiac arrest when there is –

• Sudden loss of responsiveness
• No breathing or abnormal breathing
• No response to tapping on shoulders
• No response when asked if he is OK

It is interesting to note that AHA, in its current updated guidelines, has removed the clause of mandatory pulse check by lay rescuers to ascertain cardiac arrest and suggests that they should start CPR in all presumed cardiac arrest cases when a person collapses suddenly, becoming unresponsive with either no breathing or abnormal breathing. Abnormal breathing includes gasping breaths or agonal breathing. Current evidence indicates that the risk of harm to a victim who receives chest compressions when not in cardiac arrest is extremely low.⁷ Lay rescuers are not able to determine with accuracy if a victim has a pulse. Withholding CPR of a pulseless victim has a much higher mortality risk than any unintended harm from unnecessary chest compressions. This is a significant development as, prior to 2020, it was always mandatory for laypersons to check for the carotid pulse (for not more than 10 seconds) to ascertain cardiac arrest before starting CPR.⁷

The IRC guidelines, however, have always recommended initiation of CPR by lay rescuers when a person becomes suddenly unresponsive with abnormal breathing or without any breathing efforts. The practice guidelines developed by IRC for laypersons for cardiac arrest outside hospital is called compression-only life support (COLS).2

The ability to identify cardiac arrest and start resuscitation at the scene is the most important link in the chain of survival in all guidelines. In fact, even if one of the links becomes weak, the survival chances decrease by 10%. The links in the chain of survival for both out-of-hospital and in-hospital cardiac arrest as per AHA are depicted in Fig 1. The emphasis is clearly on immediate recognition and early transfer of the victim, with ongoing CPR.

The COLS practice guidelines for lay rescuers attending to out-of-hospital cardiac arrests recommend a simpler chain of links for survival comprising early recognition, early CPR, and early transfer.

In the conventional CPR, the sequence of resuscitation was airway, breathing, and circulation (ABC), but it was recently changed to circulation, airway, and breathing (CAB).⁸ Furthermore, the AHA was also of the opinion that compression-only CPR is as effective as the full CPR.⁹ Compression-only CPR is very simple, and a layperson can do it effectively. In fact, one need not even undergo a formal CPR training to understand how it is done.^9,10 COLS is a modified, standardized, Indian version of hands-only CPR advocated by AHA.

The first step in the COLS algorithm is to identify the cardiac arrest victim and ascertain scene safety. Whenever a person suddenly collapses and becomes unresponsive with irregular or no breathing and does not respond to any kind of stimulus, he is deemed to have developed cardiac arrest and the lay rescuer should start chest compressions immediately after informing the emergency response team or calling for help. This is described in a step-wise algorithm for a single rescuer and two rescuers. The COLS algorithm for CPR by laypersons for outside hospital cardiac arrest is shown in Fig. 3.

During CPR, both hands should be placed on the lower half of the sternum, typically two finger breadths above the xiphisternum (center of the chest), and compressed in a regular rhythm. While performing chest compressions, the palms of both hands of the rescuer should be interlocked and the compressions should be initiated with the heel of the palm of the dominant hand. The elbows should be kept locked and straight during compression. He/she should repeat the count 101,102,103, etc., loudly to maintain the speed and number of chest compressions. The rate of chest compressions should be 120/min and the compression depth should be at least 5 cm or never more than 2.5 inches. The rescuer should allow complete chest recoil between compressions without lifting his hands from the chest but should not lean on the victim’s chest. There should be minimum interruptions during chest compressions. If the rescuer is alone, he/she should continue the chest compression for 5 consecutive cycles of 30 compressions each. When more than one rescuer is involved, they should switch roles every 5 cycles until there is a sign of return of spontaneous circulation or until medical help arrives. When 2 rescuers are involved, the second person encourages the first one to push hard and push fast and also ensures that high-quality CPR is being rendered. The aim of COLS is to provide continuous, uninterrupted chest compressions to improve the chances of survival and the neurological outcomes.¹⁰

High-quality CPR consists of the following:

1) Pushing hard and pushing fast, ensuring chest compressions at an adequate rate (120/min) so that at least 100 of them will be highly effective compressions.

2) To ensure chest compressions of adequate depth (at least 6 cm deep).

3) Allowing full chest recoil between compressions and minimizing interruptions in chest compressions. CPR should be stopped if the patient shows signs of return of spontaneous circulation such as becoming conscious and obeying commands, starts breathing spontaneously, or starts moving all the limbs.

CPR should not be performed if the scene of the incident is not safe, such as on a highway with speeding vehicles, at a scene of fire accident and similar places. In such cases, CPR should be administered after the victim has been moved to a safe place. CPR is also not provided if there are already tell-tale death-like signs such as rigor mortis, etc. It is most effective in witnessed cardiac arrest cases when the victim collapses suddenly in front of the rescuer, in which case, CPR is continued until help arrives and the victim is transferred to a hospital.²

Compression-only CPR or hands-only CPR is the preferred method for laypersons who witness an adult suddenly collapse. India is a vast country and therefore, indigenously designed guidelines tailored to the limited facilities available are highly desirable. Generally, people are hesitant to provide mouth-to-mouth breathing for resuscitation, especially if the victim is unknown. A vast majority of the Indian population hardly has any access to CPR training. Considering all these limitations and the advantages of compression-only CPR, the COLS algorithm has been recommended for lay personnel.²

The IRC guidelines also have a customized algorithm for health care providers rendering basic life support in out-of-hospital cardiac arrest scenarios.¹¹BCLS refers to an algorithm for CPR for outside hospital cardiac arrest victims to be used by allied health care professionals or trained paramedical staff when they reach the scene.¹¹ It is very similar to the BLS algorithm advocated by the AHA, and involves the use of AED or early defibrillation as and when applicable.

Thus, there is an addition of early defibrillation to the chain of survival links of BCLS. However, in our country, immediate and timely availability of AED at the scene is still largely questionable and hence, COLS alone would be appropriate for training the large majority of general public.

In addition, it also involves the use of rescue breaths in the ratio of 2 breaths for every 30 compressions given. Once the chest compression has been initiated, rescue breaths need to be delivered using mouth-to-mouth, mouth-to-mask, or a bag-mask-valve (BMV) device. After opening the airway using the head tilt-chin lift and jaw thrust maneuver (only jaw thrust in suspected cervical spine trauma), a breath should be delivered over 1 second. As this technique is exclusively meant for use by health care workers, mouth-to-mouth breathing should be discouraged and mouth-to-mask or rescue breathing with BMV device recommended with correct holding of the mask over the nose and mouth using the C-E clamp technique.

The BCLS algorithm is depicted in Fig. 6. In BCLS, the rescuer checks for the presence of pulse and breathing simultaneously. The pulse should be checked in either of the carotid vessels for not more than 10 seconds. During this time, he should also observe the chest for breathing movements. Absence of breathing or abnormal breathing, such as gasping or agonal breaths, and absence of pulse are suggestive of a cardiac arrest. Based on these assessments, three clinical situations might be encountered as follows:

1. Normal breathing with carotid pulse present:

The victim is placed in the recovery position and assessed every 2 min or less for any change in his condition. Based on the observations from repeated assessments, he should be managed as per the steps mentioned in the algorithm. After completing these steps, the rescuer should wait for the medical team to arrive and shift the victim to the most appropriate, nearest health care facility.

2. No breathing or abnormal breathing with carotid pulse present:

The victim has respiratory arrest and needs to be assisted by providing rescue breaths. Normal tidal volume breaths should be delivered over a period of 1 second, every 5 seconds at the rate of 12 breaths/ min with the help of a BMV device. A visible chest rise or heave is considered to be indicative of adequate ventilation. The victim should be reassessed for pulse every 2 min or earlier and do the needful as per the algorithm. The victim should then be shifted to the nearest appropriate facility at the earliest.

3. Abnormal or no breathing without a definite carotid pulse noted:

The victim has cardiac arrest and needs highquality CPR with cycles of compression and rescue breaths in the ratio of 30:2. The technique of chest compressions is similar to that described above for COLS.

If there is more than one responder, the rescuer performing chest compressions and the one providing rescue breaths need to switch roles and interchange after every five sets of CPR (five cycles of 30 chest compressions and 2 breaths) to provide effective chest compressions and also to prevent exhaustion. After completing the five sets of CPR, the victim should be reassessed by checking the pulse. During this step, the following situations might be encountered:

I. Pulse Present: Check for the presence of breath. If absent, provide a breath every 5 s and reassess every 2 min. In case of presence of breath, reassess every 2 min until the victim is shifted to the nearest medical facility.

II. Pulse Absent: Continue with five sets of CPR again and reassess the carotid pulse. Repeat the process depending on whether the pulse is present or absent. It is recommended to perform rhythm analysis if an AED or defibrillator is available, rather than pulse check after five sets of CPR until the spontaneous circulation is restored.

Early defibrillation

The defibrillation should be done at the earliest, especially if sudden cardiac arrest is confirmed. The defibrillation shock should be administered by AED or manual defibrillator by a trained rescuer. If an AED is not available, defibrillation should be done as soon as the medical team arrives with the device. Until then, highquality CPR should be continued. The first shock should be administered at the earliest, irrespective of the stage of the CPR cycle. Thereafter, the defibrillation should be continued if required, based on the rhythm shown on the defibrillator monitor.

Automated external defibrillator (AED)

If an AED is available and can be retrieved, it should be used right away.

The steps for using an AED are as follows:

1. Switch on the AED

2. Follow the voice prompts

3. Attach the AED pads without interrupting the chest compressions

4. Wait for the rhythm analysis by the AED to determine the need for electric shock

5. Do not touch the victim during rhythm analysis

6. Administer electric shock if prompted by the AED

7. Resume CPR, starting with chest compression immediately after delivering the shock.

Defibrillator

The steps for using a manual defibrillator are as follows:

1) Switch on the defibrillator

2) Attach the electrocardiography (ECG) leads of the defibrillator or keep the paddles on the chest (one at the apex of the heart on the left side of the chest and the other below the clavicle, on the right side along the mid-clavicular line).

3) Continue CPR during lead attachments

4) Analyze the rhythm. Do not touch the victim during rhythm analysis

5) If the rhythm is shockable (ventricular fibrillation or pulseless ventricular tachycardia), then charge the defibrillator with 200 J. Continue the chest compressions during charging. Deliver the shock ensuring that no part of the rescuer’s body is touching the victim or his/her bed. After delivery of the shock, resume CPR, starting with chest compression.

6) If rhythm is non-shockable, (asystole and pulseless electrical activity [PEA]) continue CPR.

Depending on whether the defibrillator is biphasic or monophasic, the shock energy should be 200 J or 360 J, respectively. The maximum shock energy available on the defibrillator should be chosen if it is not known whether it is biphasic or monophasic.

Recovery position

In case of return of spontaneous circulation and normal breathing, the victim should be placed in the recovery position, left- or right-lateral, until help arrives, as it helps maintain airway patency and also allows drainage of any oral secretions. He/she should be reassessed every 2 min or earlier as required.

Transfer

The victim needs definitive advanced medical care and management of the underlying etiology of the cardiac arrest and should be shifted to the nearest appropriate facility as early as possible. The addition of a defibrillator in the algorithm is unique and customized to the Indian scenario where the availability of AED is still not common.

COLS/ACLS

The management of a patient with cardiopulmonary arrest inside the hospital requires a systematic approach for an optimal outcome. The CCLS is a simplified algorithm-based approach for cardiac arrest victims inside the hospital until return of spontaneous circulation (ROSC).¹² It is similar to the ACLS algorithm by the AHAwhich is depicted below.²

In CCLS for in-hospital cardiac arrest, the person observing the patient collapsing should activate Code Blue or inform the local rapid response team (RRT) as per the institutional protocol. All hospitals should assign a Code Blue speed dial number in their intercom system and display the same prominently everywhere. The Code Blue team or RRT must be formed based on the duty roster, and their contact details must be prominently displayed for immediate access. After activation of Code Blue, the pulse and breathing should be assessed simultaneously. The carotid pulse needs to be checked for 5-10 s. During this process, the chest movements should be assessed for presence of breathing. The absence of breathing or abnormal breathing such as gasping or agonal breaths and absence of carotid pulse are suggestive of a cardiac arrest. In case of doubt about the presence of pulse or breaths, the patient is assumed to have cardiac arrest and high-quality CPR needs to be initiated immediately. The method of chest compression and rescue breathing is similar to what has been described earlier. In case the patient’s airway is already secured with an endotracheal tube, then chest compressions should be given continuously at a rate of 120 compressions/min, independent of the breathing and 1 breath should be delivered every 6 s at a rate of 10 breaths/min) and no ratio between compressions and ventilation needs to be maintained. As with BCLS, if there are two rescuers, they should interchange their places every 2 min to ensure high-quality CPR. It cannot be overemphasized that at no point in time should chest compressions be delayed for need of advanced airway placement or endotracheal intubation.

In case a cardiac monitor or defibrillator pads/paddles are attached to the victim, the rhythm should be checked on the monitor instead of through pulse check. However, pulse check may still be required in certain situations such as for confirming a regular rhythm without a pulse (PEA) and to identify VT with/without pulse. Defibrillation should be done at the earliest, especially in a patient with witnessed sudden cardiac arrest.

Venous access

Venous access should be secured without delay during ongoing chest compressions and ventilation. The peripheral venous access is the most preferred. The intra-osseous access which was one of the preferred routes earlier, when IV access was not available, is no longer recommended.⁷ Endotracheal route (if already intubated) of administration remains unchanged in the current guidelines. The intra-tracheal dose should be 2-2.5 times that of the intravenous dose and should be diluted to 10 mL.

Airway management

A definitive airway may be secured with an endotracheal tube if the required expertise is available. The use of supraglottic airway devices (SADs) is encouraged if the rescuer is appropriately trained and endotracheal intubation does not seem feasible.¹² The correct placement of SADs should be confirmed with end-tidal capnography (ETCO2). However, if the BMV is optimal, then securing definitive airway should be deferred and bag mask ventillation continued until expert help arrives so as to prevent unnecessary interruption of chest compression.

Antiarrhythmics

Once the vascular access is secured, adrenaline 1 mg should be administered as bolus for all types of rhythm. This needs to be repeated every 3-5 min. Early administration of adrenaline is recommended and should be performed as early as feasible.⁸ All drugs administered through the peripheral venous access must be flushed with 20 mL of normal saline. The limb should also be elevated for 10 s after the administration, to facilitate its passage into the central circulation. If arrhythmias persist even after the initial 3 cycles of CPR, then intravenous amiodarone 300 mg should be given as a slow bolus. A second intravenous dose of amiodarone 150 mg must be given if the arrhythmia persists. Lignocaine is an alternative if amiodarone is unavailable.

Assessment and management of the reversible causes

The history, medical records, and physical examination of the patient should be reviewed for any possible underlying etiologies of the cardiac arrest, and appropriate investigations ordered. However, it needs to be emphasized that during this process, the chest compressions and other aspects of resuscitation must not be interrupted.

The most common reversible causes of a cardiopulmonary arrest usually consist of 5 Hs and 5 Ts. which include hypovolemia, hypoxia, H+ ion (acidosis), hyper/ hypokalemia, tension pneumothorax, cardiac tamponade, drug toxicity, pulmonary embolism, and myocardial infarction. They need to be primarily addressed during clinical examination and blood investigations.

Transfer

After successful resuscitation, the patient should be shifted to a high dependency unit or critical care unit for definitive advanced medical and post resuscitation care.

Post-resuscitation care

Once there is ROSC, the patient requires special care in a dedicated unit. During this period, not only is the maintenance of perfusion and oxygenation of paramount importance but also the correction of the precipitating cause of cardiac arrest needs to be addressed again. Normocarbia should be maintained, and the fraction of inspired oxygen (FiO2) should be reduced to acceptable levels as early as possible. Specialist consultation is essential for assessing the need for coronary interventions. A mean arterial pressure of >65 mm should be ensured for optimal perfusion of the vital organs. In case the patient remains comatose after resuscitation, the temperature should be kept not >36ºC with targeted temperature management.^8,12

Conclusion

The management of patients with cardiopulmonary arrest both inside and outside hospital requires early identification and high-quality resuscitation, including defibrillation wherever feasible. Following the algorithms for resuscitation would improve the overall outcome. The current recommendations and guidelines recommend compression-only CPR for lay rescuers and timely referral or transfer. Simultaneous identification and correction if the cause of the cardiac arrest while continuing resuscitation, and appropriate post resuscitation care can reduce the mortality by up to 40%.

Conflicts of Interest

Authors declare that there is no conflict of interest.