Trench Foot

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Trench foot is the more commonly recognized name of the immersion syndromes that is well known in military history. The most recent and more appropriate name for this is nonfreezing cold injury (NFCI) (frostbite is a freezing cold injury). The cause is due to a prolonged exposure to conditions where are feet are in a non-freezing, damp, cold and usually unsanitary environment for a period of time. The name trench foot arose as it was a common problem of soldiers fighting in the trenches during World War I, even though it was first described during the Napoleonic Wars in the early 1800’s. The French army surgeon Dominique Jean Larrey was the first to document it. At one point in the first world war it affected over 20 000 British soldiers on the front which seriously hampered the winter 1914 campaign. A large number of cases were reported in the British army during the 1982 Falklands war. The British army boot was not as waterproof as the Argentinian boot, apparently making the Argentinian boot a prized bounty of battle.

Trench Foot and nonfreezing cold injury

While trench foot is most publicly associated with warfare and the moisture in trenches, the condition can occur at any time the foot is damp and cold (not frozen) conditions for a prolonged period of time. While trench foot or nonfreezing cold injury continues to be a problem for the military, it can also occur it may also occur in civilian populations taking part in extreme outdoor activities such as mountaineering and in those who work in hostile environments such as the fishing industry or cold storage. It is becoming increasingly recognized in homeless populations. There have been cases reported of of it occurring in an elderly man who suffered a fall spent time on a cold floor and of it also occurring in attendees at a music festival that is regularly held on muddy grounds. A report from the BBC noted:

Podiatrist Amber Kibby is a trustee director of Festival Medical Services, a charity which provides medical services at Glastonbury. Its 13 festival podiatrists are familiar with the symptoms of trench foot.
“The team started its work in 1998, which was the worst year for trench foot. We were seeing approximately 90 cases a day. Over the years, we have seen less and less of the condition. On the whole people are better prepared and they bring socks and wellies, they understand that there will most likely be mud.”

Pathophysiology:
Many aspects of the pathophysiology are:

It is not clear what the exact mechanism of injury is: it is probably due to be damage to the neuro-endotheliomuscular elements of the walls of the smaller blood vessels. Obviously, intense and prolonged vasoconstriction is the major factor in its development. It is also complicated by direct effects of cold on the nerve function and damage due to reperfusion following the ischaemia.
It is also not clear if the damage is actually vascular or neural in origin or a combination of both.
So, its not entirely clear if the primary pathophysiologic cause of the tissue damage is: thermal; ischaemic; the post-ischaemic reperfusion; or is hypoxic in origin.

Clinical Features of Trench Foot:

Early Stages of Trench Foot

Staging of Trench Foot:
Four stages are generally clinically recognized, with significant merging and overlap between the stages. The staging was first recognized by Ungley in 1942¹:

Stage One:

prehyperaemic phase; occurs during the initial exposure to the cold environment; can start within an hour of exposure;
loss of sensation/numbness and other sensory disturbances (such as proprioception) that affects gait;
initially, may be a bright red colour, but almost all change to a pale colour due to intense vasoconstriction; skin has a blanched appearance;
pain and swelling absent at this stage;
rewarming at this stage could induce stage three

Stage Two:

hyperaemic phase starts; this follows immediate removal from the cold exposure
lasts from a few hours to a few days; follows reperfusion of ischaemic tissues
change colour from the blanched white to a mottled pale blue
remains cold and numb with sensory and motor disturbances; swelling may start

Stage Three:

this is the hyperaemia stage with increased blood flow for from several days and up to several months; onset of this stage is usually abrupt; becomes a reddish colour
capillary refill time test is delayed significantly; but pulses bounding.
numbness resolves and is usually replaced with pain and increased sensitivity to light touch; pain often worse at night.
oedema progresses; blister can often form.
anhidrosis

Stage Four:

in mild cases, they may not get to this stage; this is the final stage lasting from weeks to months (though can go on forever in some individuals).
increased sensitivity to cold in the extremity (may depend on severity of initial injury).
many have persistent pain triggered by cold exposure.
some have hyperhidrosis that can be very pronounced; some loose nails.

Long term, there can be neuromotor disabilities, chronic pain; increased sensitivity to cold.

Treatment of Trench Foot:
Those with trench foot are at high risk for hypothermia which can be life threatening; core temperature needs to be raised while keeping extremities cool. The rewarming needs to take place slowly as a rapid rewarming may intensify injury. They need to be checked for dehydration and also for any signs of frostbite. The best rewarming is considered to be by exposure to warm air alone, and they must not be immersed in warm water for this. The early period after re-warming can be very painful. There are no specific drug treatments, except what may be needed for pain management. Any local wounds will need appropriate wound management.

Prevention of Trench Foot:

still a threat to military operations in cold weather; most military’s have extensive preventative documentation and practices that they use.
prevent by keeping the feet warm and dry; keep moving; changing frequently into dry clothing; fatigue and malnourishment may play a role.
the stress associated with military operations is vasoconstrictive, so this further adds to the risk factors.
It was also noted that in World War I that a key preventive measure was regular foot inspections by officers.

Recently, there were concerns that the actor Brad Pitt may be at risk for trench foot after spending days filming in mud:

Standing in mud up to his knees has left Brad with nasty feet and producers have apparently hired a chiropodist to ensure their leading man doesn’t get trench foot.