What should we do in case of sudden cardiac arrest?

Author: Zhang Huanzhou Yixi Medical College

Reviewer: Xiao Xinli, Associate Professor, School of Medicine, Xi'an Jiaotong University

In our daily life, we occasionally see someone suddenly collapse on the subway or bus, holding his chest, with a cyanotic face, cyanotic lips, and convulsions. This situation is medically called sudden cardiac arrest. So what should we do if the ambulance fails to arrive in time? The most effective measure for sudden cardiac arrest is emergency cardiopulmonary resuscitation.

According to the 2020 AHA Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, the standard steps and methods of cardiopulmonary resuscitation can be summarized as the four-step "CABD" method:

Circulation—30 chest compressions.

Airway——Open the airway manually.

Breathing——Electrical assisted breathing or artificial respiration 2 times.

Defibrillation - Administering external electric shock to defibrillate.

Let us explain the steps of CABD in detail.

Step 1: C – Perform chest compressions

Effective chest compressions require the following attention.

1. The pressing point is the middle point of the line connecting the two nipples in the middle of the sternum.

2. The correct pressing gesture is to overlap your hands up and down, interlock your fingers, and use the base of your palms to touch the patient's sternum. Pay special attention not to apply force to the ribs on both sides to avoid fractures.

3. Kneel on both knees, straighten your waist, stretch your arms, and press vertically downwards.

4. Press hard to make the sternum sink 5 to 6 cm, and relax fully after each compression to allow the patient's chest to fully rebound. The compression frequency should be fast, reaching 100 to 120 times/minute.

5. During cardiopulmonary resuscitation, try not to interrupt cardiac compression; if you have to interrupt, it is best to control it within 5 seconds and no more than 10 seconds.

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Step 2: A - Open the airway

Note that the airway must be cleared before opening it. The general method is to tilt the patient's head to one side and use fingers to pick out vomit or secretions in the airway to ensure that the airway is open. Use the following methods to open the airway:

1. Head tilt and chin lift

When the patient has no head and neck injuries, the " head tilt and chin lift method " is used, that is, the rescuer places one hand on the patient's forehead, presses down the forehead with the outer edge of the palm, and uses the index finger and middle finger of the other hand to lift the patient's chin, so that the patient's head tilts back until the line connecting the tip of the chin and the earlobe is perpendicular to the ground, thus opening the airway.

Or use the "head tilt and neck lift method", follow the same steps as above, but instead of lifting the chin, lift the patient's neck.

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2. Two-handed jaw support method

If the patient has a neck injury, in order to avoid further damage to the cervical spine, the "two-hand jaw support method" should be used. The specific method is: the rescuer is at the side of the patient's head, with both elbows at the same level as the patient's back, and holds the patient's mandibular angles on both sides with both hands, and lifts the lower jaw upward and forward with force, and the thumbs of both hands push down the lower lip to open the patient's mouth.

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Step 3: B - Artificial Respiration

Mouth-to-mouth artificial respiration is the most commonly used in daily first aid. The specific method is: the patient lies on his back, the rescuer presses the forehead with one hand, pinches the patient's nostrils with the thumb and index finger, and lifts the chin with the other hand to keep the airway open. Inhale normally, cover the patient's mouth completely with the lips, and then blow. After the blowing is completed, immediately separate the mouth and release the hand pinching the patient's nose. Blow twice continuously, each time for 1 second, and rest for 1 second. Pay attention to the rise and fall of the chest to ensure effective blowing.

If mouth-to-mouth treatment is not possible, mouth-to-nose treatment can be used, that is, cover the patient's nose with your mouth and blow air; if the patient is an infant, you can open your mouth and cover the child's mouth and nose and blow air.

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Perform 5 sets of CPR with a compression/ventilation ratio of 30:2 and evaluate the effect. Do not stop the CPR cycle until the patient wakes up or the ambulance arrives. The pause time should not exceed 10 seconds. Use AED as soon as possible if possible.

Step 4: D - Administer external defibrillation

An automated external defibrillator (AED) is needed. AEDs are usually placed in public places such as shopping malls, parks, and stations, and the boxes are eye-catching in color.

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To use an AED, you only need to follow the six words "listen to it and do what it says", that is, follow the voice prompts and screen displays of the AED. If there is no AED on site, continuous cardiac compression is also effective.

When the heart stops beating, timely CPR is crucial! When the heart stops beating for 4 minutes, the brain cells will be irreversibly damaged; after 10 minutes of cardiac arrest, even if CPR is successful, it may cause irreversible damage to the brain and brain death may occur.

After cardiac arrest occurs, it is impossible for an ambulance to arrive at the scene immediately. In this case, cardiopulmonary resuscitation is a very important life-saving skill. Only by mastering the specific operations of cardiopulmonary resuscitation can we rescue the patient to the greatest extent.