They wrapped her in electric heating pads and began the slow, tedious work of trying to raise her body temperature degree by degree.

This approach — passive external rewarming — is the most basic possible intervention, and it works very slowly.

It also carries risks that were well-understood even in 1980: rewarming a severely hypothermic patient too quickly can cause a dangerous influx of cold blood from the periphery into the core, causing the core temperature to paradoxically drop further (the phenomenon called “afterdrop”) and potentially triggering a fatal arrhythmia as the heart is hit with a surge of cold, acidic blood.

But slowly and carefully applied, rewarming from the outside is what they had.