What Is Trench Foot?

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Trench foot is an injury that occurs when feet are exposed to cold and wet conditions, but it is not due to freezing (as in frostbite). It is one of three types of immersion foot, with the other two types being warm water immersion foot and tropical immersion foot.

As the feet continue to be cold and damp, the body constricts the blood flow to prevent heat loss; this results in a lack of oxygen supply to the feet and subsequently results in damage to tissue. As the skin begins to break down, open sores and blisters often result in bacterial or fungal infections.

Trench foot and other immersion foot disorders differ according to the temperature of exposure to non-freezing, damp conditions (as well as unsanitary conditions at times).

Trench foot can develop due to wet feet for a prolonged time

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Trench Foot Symptoms

Symptoms of trench foot may include:

  • Reddened, cold blotchy skin
  • Itching
  • Prickly/heavy feeling of the foot
  • Numbness and tingling pain
  • Cramps in the legs
  • Swelling
  • Liquid filled blisters
  • Ulcers
  • Bleeding under the skin
  • Sloughing of tissue (in severe conditions)
  • Gangrene (a condition from tissue death in which the skin may turn dark blue, purple or gray that can happen in severe cases of trench foot)

Symptoms of trench foot can involve the toes, heel, or the entire foot. In very severe conditions it can cause swelling of the leg all the way up to the knee.

The symptoms usually appear after exposure to conditions for a day or two, but they can begin in as little as an hour after exposure. Some people can be exposed to a cold, damp environment for up to a week before symptoms appear.

The severity of the symptoms of trench foot depends on the temperature, how wet the feet get, and the length of exposure to coldness and wetness.

Stages of Trench Foot

Trench foot is often categorized into one of four stages, including:

Stage 1—Injury Phase

This stage involves restriction of the blood flow due to cold tissue, symptoms may include numbness and reddened skin, but pain has not yet begun.

Stage 2—Pre-hyperaemic Phase

This stage lasts from six to 24 hours. Symptoms include pale, white-colored, cold feet with paraesthesia (pins and needles sensation). The ankles and toes are stiff, making it difficult to walk.

Upon examination, a healthcare provider may not be able to palpate (feel) the normal pulses of the feet (indicating that normal blood flow has been impeded).

Stage 3—Hyperaemic Phase

This phase lasts up to two months. Symptoms include painful feet that are hot the touch. There is swelling that worsens with heat, movement, and standing.

In severe cases, small blisters may be seen. Bruising, along with petechiae (rash-like spots on the skin) may be present. When trench foot is mild, the condition usually resolves with treatment at this stage. If it is severe, trench foot symptoms progress.

Stage 4— Post-Hyperaemic Phase

This phase may last for the duration of the person’s life. This is a long-term vasospastic (narrowing of the blood vessels) phase involving increased pain on warming, hyperhidrosis (extreme and excessive sweating) of the feet, and paresthesia (pins and needles sensation).

The affected foot/feet may develop a sensation of being cold, permanently. Secondary Raynaud’s syndrome (a condition involving an exaggerated sensitivity to cold in which the toes turn blue and/or white upon exposure to cold, and then bright red on rewarming) develops as a result of long-term constriction of small blood vessels.

Study
A 2013 study, reports that trench foot usually starts with tingling and itching which progresses to numbness. Restricted blood flow can cause reddened skin and a bluish discoloration (called cyanosis). In the later stages, as the foot is rewarmed, hyperesthesia (excessive physical sensation) may occur.

Odor, decay and necrosis (death of tissue) may occur with prolonged exposure. The feet can swell in some instances significantly; in fact, there are some descriptions of the feet doubling in size due to edema (swelling).

Complications

Complications that may occur as a result of trench foot include:

  • Soft tissue infections (such as cellulitis or gangrene)
  • Subacute (moderately severe) or long-term neuropathic pain (nerve pain)
  • Permanent sensory changes could result if trench foot is not treated promptly
  • Cellulitis (an infection in the deeper layers of the skin)
  • Thrombophlebitis (inflammation of the wall of a blood vessel)
  • Muscle atrophy (the loss of decrease of muscle mass)
  • Osteoporosis (softening of the bone)
  • Injury to muscles, skin tissue, blood vessels, or peripheral nerves
  • Amputation may be required in severe cases of trench foot

Causes

The primary cause of trench foot is long periods of wet, cold feet. But, unlike frostbite, this occurs without freezing temperatures. The condition usually results from exposure to temperatures of between 32 F to 59 F. But a temperature as warm as 60 F could cause trench foot when exposure occurs over a period of at least 10 to 14 hours.

When the feet get cold, they lose heat 24 times faster than dry feet.

When the feet are cold and moist, destruction to small blood vessels (called capillaries) can lead to the breakdown of surrounding tissue. Constriction (vasoconstriction) and dilation (vasodilation) of the blood vessels is thought to be the cause of local tissue damage. Excessive sweating of the feet can also be a contributing factor to trench foot.

History of the Identification of Trench Foot

During World War I, trench warfare was a common combat tactic in Europe. Soldiers found themselves standing in wet, muddy trenches for long periods of time.

In 1914 it was observed that trench foot mostly affected the toes, but it sometimes involved the legs, which would swell up as far as the knee area. When it worsened, there were blisters filled with clear fluid that smelled foul, like gangrene.

The result was that over 20,000 British troops were reportedly treated for trench foot. It is estimated that nearly 75,000 British soldiers and 2,000 American soldiers died from health conditions that involved complications from trench foot (or from conditions that were complicated by the disorder).

But, trench foot was first discovered further back in history. In fact, it was described by a French army surgeon named Dr. Dominique Jean Larrey during Napoleon’s fight with Russia in the Patriotic War of 1812.

Trench foot is not very common among the civilian population, but it can be seen in homeless people, due to unsanitary conditions and the inability to keep feet warm and dry. The condition is also seen in fishermen because they are prone to having wet feet for long time spans, as well as hikers.

Diagnosis

A thorough physical exam, combined with an assessment of the environment and situation in which symptoms occurred, is the basis for formulating a diagnosis of trench foot.

In addition, other possible causes (such as an infection) must be ruled out. Therefore a white blood cell count (WBC) may be ordered. A bone scan or other imaging tests may be ordered to rule out any type of osteomyelitis (infection in the bone).

Treatment

Many treatment and prevention measures for trench foot are the same, these include:

  • Keeping feet clean and dry
  • Changing socks and shoes whenever they get wet
  • Elevating the feet whenever possible (this will help prevent new wounds and blisters)
  • Avoiding sleeping in socks, removing socks to air-dry feet when possible
  • Treating any affected part of the foot or leg by soaking in warm water for approximately five minutes (the temperature of the water should be between 102 and 110 F).
  • Applying heat packs to the affected area every five minutes as a means of slowly re-warming the foot
  • Taking non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen, as prescribed for pain and swelling
  • Examine the feet often for signs of infection or for worsening of the tissue breakdown
  • Seek medical attention as soon as possible

For neuropathic pain (nerve pain), your doctor may prescribe amitryptiline or other medications.

If gangrene occurs, amputation of the extremity may be required to prevent further progression of the disease, and to keep serious consequences (such as sepsis or death) from occurring.

Prevention

The best treatment for trench foot is prevention, preventative measures include:

  • Air dry the feet and keep socks and shoes dry (change them whenever necessary).
  • Keep the feet clean and dry.
  • Do not sleep with socks on. Allow air to thoroughly dry the feet. This avoids sweating.
  • Elevate your feet whenever possible to help promote circulation.
  • Wear shoes that fit well (ill-fitting shoes may contribute to trench foot).

History of Prevention of Trench Foot

During World War 1 soldiers were ordered to inspect their feet daily; they were also paired up and instructed to observe the feet of their partner (because it was discovered that a soldier was more likely to remove the socks and boots and dry the feet when a fellow soldier was there) to ensure that meticulous foot care was conducted.

After trench foot occurred in thousands of soldiers, the soldiers were all ordered to carry three pairs of socks with them at all times. They were ordered to change and rotate the dry socks at least two times each day. They were also instructed to massage the feet after they were dry with whale oil.

The trenches were kept as dry as possible using wooden boards to keep soldiers from walking in the water; these boards were called duckboards. Exposure to the outdoor elements was limited by the employment of troop rotation. These measures were found to decrease the incidence of trench foot.

Prognosis

Complete recovery is expected when trench foot is diagnosed early; but when sensation returns, there can be severe temporary pain to the affected area, even when a complete recovery is expected.

Although the symptoms of trench foot may be alleviated by slowly warming up the affected extremity, there’s a possibility of long-term (chronic) tissue damage and chronic pain, particularly in severe cases.

A person who has been diagnosed with trench foot could end up requiring long-term follow-up medical intervention for one of several potential complications of trench foot (such as long-term damage to the blood vessels).

The amount of exposure time, coupled with the severity of the influential factors (such as outdoor temperature) will factor into a person's prognosis.

A Word From Verywell

Although trench foot is not very prevalent in the civilian world, it's still possible to get it. Those who engage in outdoor activities such as camping, hiking, fishing, and other recreational sports (particularly when being outdoors in the rain for extended periods of time) should be aware of the risks of trench foot (as well as how to prevent it).

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