Final answer:
For a 4-year-old child requiring CPR, one should use one hand for chest compressions, focusing on high-quality compressions at a rate of 100 per minute to the beat of 'Staying Alive.'
Step-by-step explanation:
To perform external cardiac compressions on a 4-year-old child, you should use one hand for compression. Proper CPR technique involves applying pressure with the flat portion of one hand on the sternum in the area between the line at T4 and T9, which allows enough compression to maintain blood flow into the pulmonary and systemic circuits. It is crucial to be trained in CPR to avoid potential injuries such as broken ribs or damage to internal organs. The emphasis during CPR is on high-quality chest compressions rather than artificial respiration, with a recommendation to compress the chest at least 5 cm deep and at a rate of 100 compressions per minute, which matches the beat of the song 'Staying Alive' by the Bee Gees.