As a lifeguard, Kaia has received training in CPR. She sees a small child fighting a rip current in the ocean. Kaia swims out to retrieve the girl, trying to hold her head above water as she pulls them both to shore. When Kaia manages to get the girl up to the beach, she assesses that the young girl is not breathing. Kaia begins to perform CPR while emergency services are contacted. What is this procedure meant to do for the little girl?
A. Restart her heart so that it is in regular rhythm again.
B. Keep the blood flowing to her brain and heart oxygenated.
C. Push the water inside her lungs up through her trachea.
D. Prevent her limbs from becoming hypothermic.

During cardiac arrest, both heart and lung function stop. This means the lungs are no longer cycling in oxygen and cycling out carbon dioxide, and the heart is no longer pumping blood to itself and peripheral vital tissues. Most importantly, the heart is no longer circulating blood to the brain.

Therefore, the purpose of cardiopulmonary resuscitation (CPR) is to externally supply oxygen that can perfuse into the bloodstream and manually pump this blood to the heart, through the heart, and out of the heart to the brain. In other words, the point of this procedure is to keep blood flowing to the patient's brain and heart oxygenated, option B.

Why Not Other Choices:

Manual CPR alone does not always restart the heart (known as return of spontaneous circulation, ROSC) and restore its rhythm. For this, the patient will need defibrillation or cardioversion. During CPR, this is performed using an automated external defibrillator (AED).

Water when introduced into the lungs can become trapped within the sac-like alveoli, and pressing on the chest alone will not evacuate this water. Further, the water in the lungs is not of utmost priority during cardiac arrest; maintaining blood supply and oxygenation to the heart and brain are the priority. When ROSC is achieved, the patient may expulse much of the water in the form of emesis (vomit).

Lastly, as addressed with the water in the lungs, the blood supply and, subsequently, the temperature of the limbs is not of utmost priority; providing blood supply to the heart and brain is.