Sequence of closed cardiac massage

Place the victim on a smooth, hard, level surface on their back. Kneel beside the victim at their side. Place the middle and index fingers of your hand, that’s on the side of the victim's legs, transversely, at the tip of the breastbone.
Place the heel of the palm of your other hand on the victim's breastbone (approximately in the middle third of the breastbone) and next to your index finger.
Place the other hand directly on top of the first hand, which is positioned on the breastbone. Interlace the fingers of both hands. Fingers should not touch the breastbone.
Without bending your elbows, keeping your arms straight (perpendicular to the breastbone) and your shoulders parallel to the breastbone, apply vertical compression pressure to the breastbone and achieve a compression of at least 5 cm. Repeat the chest compression 30 times without removing your hand from the breastbone (with a frequency of not less than 100 chest compressions per minute).
• do not take your hands from the breastbone when performing chest compressions;
• after each compression, stop applying pressure and allow the chest to return to its previous position;
• try to keep the intervals between compressions as short as possible;
• perform chest compression and rescue breath in a 30:2 ratio (30 chest compressions, 2 rescue breaths) (1 cycle);
• count each chest compression out loud;
• if a second person is assisting, switch roles every 5 cycles or every 2 minutes. Ensure the switch takes no longer than 5 seconds.
In children over 1 year old, chest compression is performed with one hand (can also be done with both hands). Chest compressions should be approximately 5 cm deep (assuming the compression rate of 100 per minute).
To perform chest compression for infants (0–1 year old), place 2 fingers in the center of the breastbone, just below the imaginary line connecting the nipples. Press down frequently and rhythmically, and ensure a 4 cm depth for each chest compression (maintaining a compression rate of around 100 per minute).

If assistance is provided by two people, closed cardiac massage is performed using the “2 thumbs” method. The first person places both thumbs in the center of the breastbone, with the other fingers supporting the chest from the sides and back. He presses the breastbone 15 times with both thumbs. The second person opens the airway and gives 2 rescue breaths. Cardiopulmonary resuscitation is continued in a 15:2 ratio (15 compressions and 2 rescue breaths).