A dangerous effect of rapidly re-warming a hypothermic patient is?

Rapidly re-warming a hypothermic patient can lead to vasodilation and hypotension due to several physiological responses in the body. When a hypothermic patient is warmed too quickly, there is a sudden increase in blood flow to peripheral areas, causing blood vessels to dilate. This vasodilation can result in a drop in blood pressure, or hypotension, as blood is directed away from the core and central circulation, potentially leading to inadequate perfusion of vital organs.

The risk of hypotension is heightened because the body, after experiencing cold, may react dramatically to the sudden change in temperature, leading to further complications. It's crucial to re-warm hypothermic patients gradually to prevent such dangerous effects.

In contrast, the other potential effects from the other choices don't represent the primary danger associated with rapid re-warming. Hyperthermia, tachycardia, arrhythmias, and cardiac arrest are serious complications that can occur but are not the immediate consequence of re-warming as seen with vasodilation and hypotension. Sepsis and infection are also serious but are less likely to be directly caused by rapid re-warming in this context.