Final answer:
Transfusing distilled water into a patient's bloodstream can cause the red blood cells to swell and burst due to osmotic imbalances, leading to circulatory shock and potential multi-organ failure.
Step-by-step explanation:
If a patient who has suffered a severe hemorrhage receives a large transfusion of distilled water directly into a major blood vessel, it will likely lead to catastrophic physiological consequences. Unlike isotonic solutions that match the osmotic pressure of blood, distilled water is hypotonic.
When it enters the bloodstream, it causes a sudden decrease in blood osmotic pressure, resulting in a rapid influx of water into red blood cells (erythrocytes). This can lead to the swelling and eventual bursting (hemolysis) of the erythrocytes. The result of such an event includes disrupted blood circulation, circulatory shock, and possible multi-organ failure.
This scenario exemplifies why proper blood or substitute transfusion is vital and why isotonic solutions are used to prevent drastic osmotic changes in patients' blood cells. The injection of distilled water, instead of an isotonic solution, would certainly not be isotonic, as evident by the destruction of red blood cells. Such an error would threaten the life of the patient due to the mechanisms similar to those seen in cases where incompatible blood types are transfused, leading to immune reactions and hemolysis.