CPR chest compressions: the technique that saves a life

When a heart stops, blood stops circulating and the brain begins to run short of oxygen within minutes. Chest compressions do not replace the heart, but they keep enough blood flowing to delay brain damage. That gained time, minute after minute, is what allows rescue teams or an automated external defibrillator (AED) to step in with better chances of success. A bystander who compresses the chest while waiting for help does not replace a medical team, but plays a role no one else can fill at that exact moment.

Before starting compressions, make sure the situation calls for them. A person in cardiac arrest does not respond when spoken to or touched, and is not breathing normally, or not breathing at all. Irregular, noisy gasps in the first seconds should not delay action, this misleading sign often accompanies the onset of arrest. The reflex to follow is simple. Call emergency services straight away, have someone fetch a defibrillator if one is available on site, then begin compressions without waiting for a medical confirmation that will not come in time.

The victim must be lying on their back, on a firm surface. The rescuer places the heel of one hand at the centre of the chest, on the lower half of the sternum, and lays the other hand on top, interlacing the fingers. Arms stay straight, shoulders directly above the hands, using body weight rather than arm strength alone.

Pushing must be firm and steady, with a full release between compressions to let the chest wall return to its shape. Compressions that are too gentle, out of fear of hurting the victim, lose much of their effectiveness. Broken ribs remain possible but they heal, unlike the brain damage caused by insufficient compressions. The rhythm should stay steady and sustained, without unnecessary pauses, from the start until rescue teams take over or the rescuer becomes exhausted.

Some habits limit the effect of chest compressions without the rescuer noticing. Stopping too often to check breathing or pulse lets blood pressure drop each time. Pushing too softly, misplacing the hands, or letting the chest sag towards the end of an effort also reduces the amount of blood pushed with each compression. Fatigue sets in fast, often before the rescuer even feels it, which is why it helps to switch with another person roughly every two minutes when possible, without interrupting the gesture beyond the time it takes to swap.

Chest compressions and the automated external defibrillator (AED) work together, they do not replace one another. As soon as the device arrives, switch it on and follow the voice prompts while continuing compressions, which only stop for the time needed to attach the pads and let the device analyse the heart rhythm. If a shock is advised, the device says so clearly and no one should touch the victim during analysis or while the shock is delivered. Compressions resume immediately afterwards, following the device's instructions, until professional rescuers take over.

The technique adjusts to the victim. For a child, one hand is often enough to compress the chest to the right depth, depending on their build. For an infant, two fingers placed at the centre of the chest replace the palm of the hand. For a pregnant woman, compressions are performed the same way, tilting the victim slightly onto her left side if several rescuers are present, to reduce pressure on the abdominal vessels. In every case, the principle stays the same, push hard and fast, without waiting for ideal conditions that will not come.