Jean Hilliard’s case sits somewhere in this zone.

The evidence suggests she was profoundly hypothermic — possibly at core temperatures associated with what would, in the absence of treatment, have been certain death.

But “in the absence of treatment” is the crucial qualifier.

With treatment, she recovered.

The zone of uncertainty has expanded enormously since 1980.

The accumulation of extreme survival cases, combined with the development of ECMO and other aggressive rewarming techniques, has pushed the boundaries of what is considered potentially survivable far beyond what the medicine of Jean Hilliard’s era would have predicted.

What this means for hypothermia management is clear: be aggressive.