Table 3.

Major pathophysiologic factors in different phases in freezing cold injuries.

Staging	Description	Pathophysiology factors
Stage 1	Pre-freezing Phase	Tissue cooling with accompanying vasoconstriction and ischaemia; no ice crystal formation
Stage 2	Freeze-thaw phase	Ice crystal formation start extracellularly (slow in-freeze) or direct intracellularly (rapid in-freeze)
Stage 3	Vascular stasis phase	Reperfusion injury, coagulation within the vessels, thrombosis, plasma leakage and shunting
Stage 4	Ischaemic phase	Progressive tissue ischaemia and infarction, inflammation