A CPR (chest compression) feedback device measures the quality of compressions while they are being given and tells the rescuer, in real time, what to adjust. High-quality compressions are one of the most important factors in survival from cardiac arrest, and even trained rescuers tend to drift from the targets without feedback.
What it monitors
- Compression depth. For adults, the American Heart Association recommends at least 2 inches (5 cm) but not more than about 2.4 inches (6 cm). Rescuers often push too shallow, especially as they tire.
- Compression rate. 100 to 120 compressions per minute. Too slow reduces blood flow; too fast reduces depth and refilling of the heart.
- Full chest recoil. Letting the chest rise completely between compressions allows the heart to refill. Leaning on the chest is a common error that devices detect.
- Hand position. Some devices check placement on the lower half of the breastbone.
- Pauses and compression fraction. The share of time spent actually compressing; guidelines aim for at least 60%, ideally higher. Long pauses for rhythm checks or switching rescuers are flagged.
- Ventilations, in some systems: the number and volume of breaths.
How the devices work
- Accelerometer pucks placed under the rescuer’s hands measure movement and calculate depth and rate.
- Defibrillator pads with sensors, built into many professional and some public-access defibrillators (AEDs), give voice prompts such as “push harder” or “good compressions.”
- Training manikins with sensors record every compression and give a score, used in CPR courses.
- Smartphone and smartwatch apps can give rate guidance with a metronome, though depth measurement is less reliable.
Feedback devices work on firm surfaces; on a soft mattress, accelerometers may overestimate depth. Some systems correct for this with a second sensor.
Where they are used
Ambulances, hospitals and CPR training centers use them most. The AHA supports the use of feedback devices in training and considers them reasonable during real resuscitation to improve performance.
What matters if you do not have one
- Call 911 and ask someone to bring an AED.
- Push hard and fast in the center of the chest, to the beat of a song around 100-120 BPM (the classic example is “Stayin’ Alive”).
- Let the chest come back up fully each time.
- Minimize interruptions, and switch rescuers every two minutes if possible.
- Use the AED as soon as it arrives and follow its prompts.
Hands-only CPR is recommended for untrained bystanders helping an adult who suddenly collapses. A short course from the American Heart Association or Red Cross builds confidence; the MedlinePlus CPR guide walks through the steps. For other first-aid myths, see can you swallow your tongue.
