Final answer:
Ineffective CPR can be caused by incorrect hand placement leading to broken ribs or sternum, internal injuries, or improper technique. It's crucial for the hands to be positioned between T4 and T9 on the sternum, and CPR must be timely to prevent brain damage.
Step-by-step explanation:
When chest compressions during CPR are not effective, there are several possible reasons. If compressions are not performed correctly, such as if an individual is untrained or too aggressive in the application, it can lead to broken ribs or a broken sternum, and potentially cause severe internal injuries, including damage to the liver if the xiphoid process is driven into it. The hands must be positioned correctly on the sternum, specifically between T4 and T9, to ensure the blood within the heart can effectively be pumped into the systemic and pulmonary circuits.
In cases of drowning, CPR is best performed after the victim is removed from the water, as it is ineffective in aquatic environments. Moreover, immediate CPR is critical for brain survival, but prolonged lack of oxygen may lead to irreversible brain damage or death, emphasizing the need for timely and proper application of CPR.