Final answer:
In child BLS, the correct depth for chest compressions is at least 5 cm, or about one third the depth of the chest, to effectively circulate blood, particularly to the brain, during CPR.
Step-by-step explanation:
In child BLS (basic life support), chest compressions should be to a depth of at least 5 cm, or about one third the depth of the chest itself. This emergency technique, known as cardiopulmonary resuscitation (CPR), is crucial when a child's heart stops beating. By correctly pressing on the sternum between the lines at T4 and T9, one can manually compress the heart enough to circulate blood into the pulmonary and systemic circuits. The blood flow maintained by CPR is especially critical for the brain to prevent irreversible damage or death of neurons. It's essential to ensure that individuals performing CPR are properly trained to avoid causing injury to the patient, such as broken ribs or liver damage due to incorrect hand placement.