Final answer:
The nitroglycerin patch should be removed immediately during a cardiac arrest to prevent any interference with life-saving treatment measures like defibrillation.
Step-by-step explanation:
A nitroglycerin patch discovered on the chest of a 75-year-old patient in cardiac arrest should be removed immediately. Nitroglycerin patches are used to deliver nitroglycerin through the skin to help relieve chest pain or to improve blood flow in persons with certain heart conditions. However, during cardiac arrest, immediate actions are crucial, and the presence of a patch can interfere with certain treatments like defibrillation, where it can cause burns if not removed. It is important to clear the chest area to allow for proper administration of cardiac life support measures.