High-Quality CPR for Adults, Children, and Infants
The measurable elements
High-quality CPR is defined by numbers a candidate must recall precisely. Compress at 100–120 per minute, at a depth of at least 5 cm (2 inches) but no more than 6 cm in an adult, at least one third of the anteroposterior chest depth in a child (about 5 cm / 2 inches) and in an infant (about 4 cm / 1.5 inches). Allow full chest recoil, keep the hands in place, minimize interruptions to less than 10 seconds, and avoid excessive ventilation. Compression fraction - the proportion of arrest time spent compressing - should be at least 60%, with higher being better.
Position and ratio
Adults: heel of one hand on the lower half of the sternum, second hand on top. Children: one or two hands depending on size. Infants: two fingers just below the nipple line for a single rescuer, or the two-thumb encircling technique for two rescuers. Ratios are 30:2 for adults (single or two rescuers) and for a single rescuer in children and infants; two rescuers use 15:2 for children and infants. With an advanced airway in place, compressions become continuous.
Traps
Questions love to offer "check the pulse again" or "let the AED analyze" as a reason to stop compressions, or to swap the infant depth for the adult number. Another trap is switching compressors only at the end of the code - rotate roughly every 2 minutes (about every 5 cycles) or sooner if fatigued, with the switch taking under 5 seconds.
Rule of thumb
If the compressor says they are not tired, they are probably not compressing hard enough - measure quality by rate, depth, recoil, and hands-off time, not by how the rescuer feels.