2020 Korean Guidelines for Cardiopulmonary Resuscitation. Part 3. Adult basic life support



## Reinforced role of the emergency medical dispatcher
Implementing a dispatcher-assisted cardiopulmonary resuscitation (CPR) program can be effective in improving the survival outcomes of adult victims of cardiac arrest. It is recommended that emergency medical dispatchers (EMDs) apply standardized algorithms to quickly detect cardiac arrest when receiving an emergency call.

## Change of the 2015 bls guidelines
If the rescuer is alone and has a mobile phone, he/she should start CPR immediately after turning on the speaker of the mobile phone or activating the hands-free function and getting assis-tance from an EMD. If the victim is not lying on a bed, he/she should be placed on a hard floor, and chest compressions should be performed; if he/she is lying on a bed in a hospital, a backboard should be inserted between the mattress and his/her back and chest compressions should be performed. The victim should not be moved from a bed to the floor to improve the depth of chest compressions. For adult victims, chest compressions should be restarted immediately after defibrillation. The rescuer could consider stopping chest compressions every two minutes to check the heart rhythm. Chest compression can be temporarily stopped to check the rhythm when physiological indicators that suggest return of spontaneous circulation (ROSC) (waveforms in the artery or rapid increase in end-expiratory carbon dioxide) are noted.

## Duration of cardiopulmonary resuscitation on the scene
Emergency medical technicians (EMTs) should consider hospital transfer if ROSC does not occur after on-site BLS is performed for 6 minutes. EMTs should consider hospital transfer if ROSC does not occur after on-site advanced resuscitation is performed for 10 minutes; however, they may consider extending the duration based on the medical directions of a physician.

## Airway obstruction by a foreign body
Tapping on the back is recommended as a priority treatment for patients with airway obstruction caused by a foreign body and for patients who are unable to cough effectively. The abdominal push method is recommended when back tapping is not effective.

## Drowning patient
Bystander CPR should be performed for victims of cardiac arrest as a result of drowning. If the rescuer is trained and willing to perform, standard CPR including ventilation should be performed. The use of an automated external defibrillator (AED) can be considered for victims of cardiac arrest as a result of drowning. A well-trained aquatic rescue team with appropriate equipment may consider underwater CPR and CPR on a lifeboat. It is suggested that immersion time and not age, emergency medical system (EMS) response time, water type (fresh or salt water), water temperature, or witnessed status of the victim, could be used as a prognostic indicator when making search and rescue decisions for drowning victims.

## Cardiopulmonary resuscitation for persons suspected to have coronavirus disease
Regarding the current coronavirus disease 2019 (COVID-19) pandemic, chest compressions and CPR can trigger the formation of aerosols, increasing the risk of transmission of infection. Health-care providers should wear appropriate personal protective equipment, including masks, gloves, and goggles. If defibrillation is necessary, it should be actively performed while paying attention to the transmission of infection. Chest compression should be performed with the victim's mouth and nose covered as much as possible because even though the risk of infection transmission is low, there is still potential for aerosol generation.

## Adult bls algorithms
In the 2020 guidelines, the adult BLS algorithms are classified according to location and rescuer: out-of-hospital algorithm for lay rescuers, out-of-hospital algorithm for healthcare providers, and in-hospital algorithm for healthcare providers.

## Adult out-of-hospital cardiac arrest (ohca) algorithm for lay rescuers
The first step of BLS is to check for responsiveness. The safety of the scene needs to be assessed first before approaching the collapsed person. If the collapsed person is unresponsive, a 119 emergency call and a request for an AED should be made immediately, and the rescuer should follow the instructions of the EMD. If normal breathing is observed, the rescuer should continue observing the patient and wait for the EMTs to arrive. If a patient has apnea or abnormal respiration (e.g., agonal respiration), the rescuer should start compression-only CPR. Standard CPR (chest compression: ventilation = 30:2) is recommended if the rescuer knows how to ventilate and is willing to provide ventilation. If the rescuer can use an AED, defibrillation should be performed according to the voice instructions of the AED. If defibrillation is not required or immediately after defibrillation, CPR should be performed for 2 minutes, and cardiac rhythm should be analyzed again with the AED. CPR should be performed until EMTs arrive, the victim moves, or breathing returns to normal.

## Adult ohca algorithm for healthcare providers
After making a 119 emergency call for the unresponsive patient, the victim's pulse and breathing should be checked simultaneously within 10 seconds. If there is no pulse or if breathing is not normal, chest compressions should be started with a compression-ventilation ratio of 30:2. When the AED arrives, cardiac rhythm should be analyzed every 2 minutes, and defibrillation should be performed if necessary. If direct medical control is possible, follow the directions, and consider transfer to a hospital after 6 minutes of on-scene CPR.

## Adult in-hospital cardiac arrest algorithm for healthcare providers
It is important to prevent the occurrence of cardiac arrest by recognizing early warning signs of cardiac arrest, such as abnormal vital signs. If cardiac arrest is suspected, the healthcare provider should check the victim's responsiveness. If the victim is unresponsive, the healthcare provider should activate the rescue team (rapid response team) in the hospital. Thereafter, the subsequent procedures to be performed are the same as those of the out-ofhospital algorithm for healthcare providers. CPR should be performed until the rapid response team arrives.

## Check responsiveness
The safety of the scene and the possibility of infection needs to be assessed first before approaching the collapsed person. Responsiveness can be evaluated by shouting, "Are you alright?" to the collapsed person, and by tapping his/her shoulder.

## Activation of ems
If the collapsed person is unresponsive, a 119 emergency call should be made immediately, and a request for an AED needs to be made. If one witnesses a person collapse, he/she needs to request that someone call 119 by loudly asking others nearby for help; the rescuer should call 119 if there is no one else around. It is challenging for a lay rescuer to precisely evaluate a victim's respiration status.Thus, a lay rescuer needs the help and guidance of an EMD to determine the respiration status of a patient and to perform compression-only CPR.Since seizures may be observed in some cases, the EMD should be able to reliably identify abnormal breathing and myoclonic muscle spasm and be able to realistically explain these possible scenarios to the rescuer. 4

## Call first regardless of age
It is difficult to classify and educate the public on different protocols and to know the cause of collapse at the scene. Further, since it is important to shorten the time to arrival at the hospital, rescuers are encouraged to call first and then initiate CPR regardless of the age of the patient.

## Call 119
When calling 119, the location of the incident, the situation, the victim's status, and the emergency treatment being provided need to be reported.If the rescuer is not trained on CPR or has forgotten the procedure for CPR, he/she should follow the instructions of the EMD. If the rescuer is alone and has a mobile phone, he/ she should start CPR immediately after turning on the speaker of the mobile phone or activating the hands-free function and getting assistance from an EMD. Putting the call on speaker is effective for conducting CPR according to the EMD's instructions.

## Dispatcher-assisted cpr
The EMD can assist a lay rescuer in recognizing cardiac arrest and performing CPR. An EMD should ask the caller if the collapsed person is responsive and if his/her respiration is abnormal.The EMD determines whether cardiac arrest has occurred if the collapsed person is unresponsive and has apnea or abnormal respiration. If an EMD recognizes cardiac arrest, the dispatcher will provide instructions on how to perform compression-only CPR via telephone.EMDs providing instructions for CPR to lay rescuers increases bystander CPR rate and improves the survival rate of victims of cardiac arrest.It is recommended that the training of EMDs should include how to detect abnormal breathing and how to teach chest compression; they should also be taught that agonal breathing means cardiac arrest and that a convulsive attack may be the first symptom of cardiac arrest.The person in charge of the EMS should shorten the time from the emergency call to the initiation of CPR, evaluate the appropriateness of dispatcher-assisted CPR, and assess the survival outcomes of patients to improve the survival of cardiac arrest. 9,10 To ensure the successful functioning of the dispatcher-assisted CPR process, a quality control process, including a review of the audio recordings of EMS calls, should be conducted as part of the prehospital EMS quality improvement process.

## Assessment of breathing (and pulse check)
The patient's respiration should be evaluated after responsiveness is determined and the 119 call is made. The lay rescuer should initiate chest compressions according to the directions of the EMD if there is abnormal or no breathing. A healthcare provider should check the absence or presence of a pulse and normal respiration within 10 seconds after activating the EMS and asking for an AED. Recognizing agonal breathing as a sign of cardiac arrest is important for rapid CPR and increases the success rate of resuscitation.In the case of normal breathing, the victim should be placed in a recovery position to prevent aspiration of a foreign body in the mouth. To determine the pulse of an adult victim of

## Chest compression
It is recommended that lay rescuers perform compression-only CPR for adult victims of cardiac arrest. For adults, the depth of compression should be approximately 5 cm, and the rate should be maintained at 100-120/min.The recommended position of one's hand when performing compression is at the lower half of the sternum. The recoil of the chest needs to be maximized after each compression.The suggested compression-ventilation ratio is 30:2.Considering the high quality of CPR and the fatigue of a rescuer, the role of a compressor needs to be rotated every 2 minutes.In the 2015 guidelines, it was recommended that lay rescuers should perform chest compression-only CPR, and rescuers who can perform ventilation should perform standard CPR including ventilation. Healthcare providers, including EMTs, should always perform CPR with both compression and ventilation.In the case of asphyxial arrest due to drowning or poisoning, or if the rescue happened a long time after cardiac arrest, ventilation should be performed with chest compression.
If an advanced airway is in place, it is suggested that one rescuer continue compression at a rate of 100-120/min without interruption, while the other rescuer provides respiration with a bag valve mask every 6 seconds (10 breaths/min).
For adult patients in a hospital, if an advanced airway is in place, it is suggested that the rescuer perform positive pressure ventilation without stopping chest compression. During CPR, the rescuer can stop chest compression every two minutes to check cardiac rhythm. 26 We recommend that the patient is ventilated with an inspiration duration of 1 second and with the tidal volume as the patient's rising chest is visually identified. Ventilation should be provided once every 6 seconds (10 breaths/min) and an advanced airway should be inserted if two or more healthcare providers are avail-able. Hyperventilation should be avoided during rescue breathing. The tidal volume should be maintained at 500 to 600 mL (6-7 mL/kg) during adult CPR.Mouth-to-mouth ventilation is recommended to provide rescue breathing to the victim. The most common cause of failure in ventilation is inappropriate opening of the airway. If the victim's chest does not rise during the first attempt, ventilation should be conducted again after properly performing the head tilt-chin lift maneuver. When respiration assistance is needed for a victim with spontaneous circulation (e.g., when a strong palpable pulse is detected), ventilation should be performed every 5 to 6 seconds or 10 to 12 per minute. BMV is a method used to provide positive pressure ventilation without an advanced airway. A rescuer provides about 500 to 600 mL of tidal volume using an adult bag mask. This should be performed for 1 second, and oxygen (concentration greater than 40%, minimum of 10-12 L/min) should be provided if possible.This procedure is most effective when two or more experienced rescuers use the bag mask.

## Airway and ventilation
After the advanced airway is in place, chest compressions should be performed at 100 to 120 per minute without interruption, and ventilation should be performed every 6 seconds (10 breaths/min). Healthcare providers can choose either a bag-mask or an advanced airway while CPR is performed for adult victims of cardiac arrest. A SGA or endotracheal tube can be inserted to serve as an advanced airway.

## Duration of on-scene cardiopulmonary resuscitation
Lay rescuers should provide BLS until the arrival of the EMTs. Healthcare providers in the hospital should provide BLS until the arrival of the rapid response team. EMTs should consider hospital transfer if ROSC does not occur after on-site CPR is performed for 6 minutes (three cycles of CPR). If advance resuscitation is possible on the scene, EMTs should consider hospital transfer after performing on-site advanced resuscitation for 10 minutes and may consider extending the time according to the direct medical directions of physicians.
In the case of normal breathing and circulation regardless of unresponsiveness, the victim should be placed in a recovery position to prevent aspiration of foreign body in the mouth.

## Defibrillation
Despite the importance of an AED, its usage rate is low.The AED is systematically registered and managed to increase its utilization. The emergency medical information website (http://www. Kyoung-Jun Song, et al. e-gen.or.kr) and app service provide guidance services and information on AEDs placed in nearby locations.The EMD informs the rescuer of the location of a nearby AED by checking the location of the AED deployed around the site of the cardiac arrest or using a mobile phone app or text message system.An AED should be used immediately it arrives. If an AED arrives while CPR is being performed, one rescuer should use the AED while the other continues CPR. After taking off the victim's shirt, two pads need to be firmly attached to his/her bare chest. Chest compressions need to be stopped while the AED analyzes the cardiac rhythm of the victim. If defibrillation is required, the AED says, "need defibrillation" and charges the defibrillator by itself. If a voice or screen instruction says, "push the shock button" after charging, the rescuer must ensure that no one touches the patient for safety purposes; the shock button can then be pushed. Chest compressions must be resumed immediately after defibrillation.
Chest compression should not be stopped except while cardiac rhythm is being analyzed or a shock is being delivered. After delivering a shock, chest compression should be restarted immediately. After every 2 minutes of CPR, the cardiac rhythm should be analyzed and the victim's status should be checked. Advanced life support should be started if available.

## Airway obstruction by a foreign body
Foreign bodies can cause mild or severe airway obstruction. If an individual with sudden respiratory distress shows signs of airway obstruction, first aid should be administered immediately. If symptoms such as cough, cyanosis, difficulty breathing or speaking, or gripping of the throat are observed, the person should be asked, "Are you choking?". If the victim nods because he/she is not able to speak, it is judged as serious airway obstruction and immediate treatment is required.
Back blows on the back are recommended as a priority treatment for persons with airway obstruction caused by a foreign body or who are unable to cough effectively. It is recommended that the abdominal thrust method be used when back blows are not effective.
If a foreign body is visible in the mouth of an unconscious person, the rescuer should consider removing the foreign body with a finger. If removing by hand is difficult, the rescuer may use instruments such as a laryngoscope and Magill forceps to remove the foreign body.

## Drowning
Bystander CPR should be done for victims of cardiac arrest as a result of drowning. If the rescuer is trained and willing to perform, standard CPR, including ventilation, is performed. The use of an AED can be considered for victims of cardiac arrest as a result of drowning. A well-trained aquatic rescue team with appropriate equipment may consider underwater CPR and CPR on a lifeboat. It is suggested that immersion time rather than age, EMS response time, water type (fresh or salt water), water temperature, and witnessed status of the victim, could be used as a prognostic indicator when making search and rescue decisions for drowning patients.

## Ethical issues related to cardiopulmonary resuscitation
The individual's right to decision and self-determination regarding CPR should be respected. However, since CPR must be performed without delay, this may result in unnecessary or unwanted results.Victims of cardiac arrest should be provided CPR immediately; however, there are a few exceptions: 1) when the rescuer is at risk of serious injury; 2) when there are obvious clinical signs of death such as post-mortem stiffness, amputation, or decay; and 3) when there is an indication meaning "Do Not Resuscitate." The rescuer who initiated BLS should continue CPR until one of the following scenarios occur: 1) EMTs arrive and take over; 2) ROSC occurs; 3) the rescuer becomes tired or the situation becomes dangerous for him/her; and 4) a contraindication for CPR is discovered during the procedure.

## Consideration of the coronavirus disease pandemic
Regarding the current COVID-19 pandemic, chest compressions and CPR can trigger the formation of aerosols, increasing the risk of transmission of infection. Chest compression should be performed with the victim's mouth and nose covered with a face mask or a cloth as there is potential for aerosol generation. If defibrillation is necessary, it should be actively performed while paying attention to the transmission of infection. Healthcare providers should wear appropriate personal protective equipment, including mask, gloves, gown, and goggles. For ventilation, healthcare providers should use a bag-mask and connect a high-efficiency particulate air filter if possible. When transferring a patient to a hospital, it is recommended that a negative pressure ambulance or a negative pressure transfer device be used if available. Figs. 4 and 5 show the modified CPR algorithm for patients suspected to have COVID-19.