 The use of the word "trench" in the name of this condition is a reference to trench warfare, mainly associated with World War I.Affected feet may become numb, by erythema (turning red) or cyanosis (turning blue), as a result of poor blood supply, and may begin emanating a decaying odor if the early stages of necrosis (tissue death) set in.As the condition worsens, feet may also begin to swell.