Final answer:
Rapid injection of certain drugs, like a potassium solution, can be fatal due to disruption of vital functions, such as cardiac arrest. If an isotonic saline solution leads to red blood cell destruction, it suggests the solution was not truly isotonic, implying it may have been either hypotonic or hypertonic.
Step-by-step explanation:
Injecting certain drugs too rapidly into a vein can indeed be fatal. For example, injecting a potassium solution into a person's blood is lethal and is used in both capital punishment and euthanasia. High levels of potassium can disrupt the electrical signals that control the heart, leading to cardiac arrest. Similarly, if a doctor injects what is believed to be an isotonic saline solution, but the patient dies and an autopsy reveals that many red blood cells have been destroyed, it suggests that the solution was likely not isotonic. An isotonic solution has the same salt concentration as human blood, so it should not cause red blood cells to burst (hemolysis) or shrink. If the red blood cells were destroyed, the solution might have been hypotonic (lower salt concentration than blood), resulting in red blood cells swelling and bursting, or hypertonic (higher salt concentration), causing them to shrink and potentially die.