For a 7-year-old patient in sudden cardiac arrest, chest compressions during CPR should be performed at a rate of 100 to 120 compressions per minute. The compressions should be given with a depth of about one-third to one-half the chest's depth, approximately 2 inches (5 cm). The recommended CPR compression- to-ventilation ratio for a single rescuer is 30 compressions followed by 2 rescue breaths (30:2). If there are two rescuers, the ratio typically changes to 15:2. This rate and technique help maintain blood flow and oxygen delivery during resuscitation efforts until advanced care arrives or the child recovers.