Trench Foot and Immersion Foot Syndrome

Trench foot, or immersion foot syndrome, is a serious condition that results from your feet being wet for too long. The condition first became known during World War I, when soldiers got trench feet from fighting in cold, wet conditions in trenches without the extra socks or boots to help keep their feet dry. Feet suffered gravely in the waterlogged trenches, as tight boots, wet conditions, and cold caused swelling and pain. Prolonged exposure to damp and cold could lead to gangrene and even amputation of the feet in severe cases.

Symptoms of trench foot include a tingling and/or itching sensation, pain, swelling, cold and blotchy skin, numbness, and a prickly or heavy feeling in the foot. The foot may be red, dry, and painful after it becomes warm. Blisters may form, followed by skin and tissue dying and falling off.

It can take three to six months to fully recover from Trench Foot and prompt treatment is essential to prevent gangrene and possible foot amputation. What is this? The medical term for Trench Foot is Non-Freezing Cold Injury (NFCI) and it is also known as Immersion Foot or Crumpet Foot. If a trench subsided, or new trenches or dugouts were needed, large numbers of decomposing bodies would be found just below the surface. These corpses, as well as the food scraps that littered the trenches, attracted rats.

Other Names

  • Peripheral vasoneuropathy
  • Nonfreezing Cold Injury (NFCI)
  • Acute trench foot
  • Chronic trench foot
  • Immersion foot
  • Sea boot foot
  • Bridge foot

Pathophysiology

  • General
    • Trench foot is a type of nonfreezing cold injury; moisture is required to produce an NFCI
    • It is typically accompanied by moisture, sometimes infection, resulting in a peripheral vasoneuropathy
    • NFCI is affected the nerves, microvasculature, and soft tissue of the distal limbs, most often the feet
    • Overall, the pathophysiology is poorly understood and described
  • Acute trench foot
    • Thrombi form, causing vascular occlusion and tissue death, nerve fiber inflammation
  • Chronic trench foot
    • Partial recanalization of vessels may occur, but residual symptoms persist
    • Chronicity tends to follow repeated episodes of acute trench foot, resulting in ‘chronic trench foot’
    • This leads to increasing severity, necrosis and potentially cellulitis, sepsis
  • Natural history
    • Most cases described with cold, wet extremities for at least one to three days
    • but NFCI can develop after 14 to 22 hours of exposure to seawater at 0 to 8 °C
    • Typically occurs in wet, cold conditions in patients who are unable to remove their shoes or boots whilst they are relatively immobile.
    • Patients are also usually fatigued and calorie-depleted.

Causes

  • Nonfreezing cold injury (NFCI)
    • Exposure to cold temperatures just above freezing
    • Predominant manifestations are dysfunction of circulatory control and injury to the microcirculation
    • If sufficient duration and severity result in neurovascular changes, leading to peripheral vasoneuropathy
    • Combined with moisture and pressure, drives reactive hyperemia with subsequent edema and destruction of capillaries
    • This impairs tissue perfusion, leading to the destruction of nerves and tissue necrosis
    • Blood flow is reduced in the toes due to a reduction in arterial diameter
    • Reduced blood flow leads to ischemia and subsequently reperfusion injury, which can result in long-term tissue damage
  • Nerve conduction
    • Among UK servicemen, nerve conduction was normal, however intra-epidermal nerve fiber density was markedly reduced in 91% of patients
    • Animal models show a reduction in nerve conduction, distal degeneration of nerve fibers after cold exposure
    • Cold exposure primarily affects sensory fibers, with 95% of patients with NFCI experiencing neuropathic pain
  • Frostbite
    • Trench foot, a non freezing cold injury, should be distinguished from frostbite, a freezing cold injury
  • Tinea Pedis
  • Cellulitis
  • Occupations (with risk of cold, wet feet)
    • Military
    • Fish processers
    • Harbor workers
  • Sports/ Recretional
    • Diving[10]
    • Hiking
    • Mountaineering
    • Festival attendees
  • Military Training[11]
    • Winter training exercises
    • Younger, unseasoned soldiers
    • Afro-Caribbean troops
  • Socioeconomic/ Other
    • Homelessness
    • Alcoholism
    • Inability to dry socks, boots
    • Immobility
    • Wet clothing or footwear
    • Poor caloric intake
  • General
    • Hypothermia
  • Freezing
    • Frostbite
  • Non-Freezing
    • Chilblains (Pernio)
    • Cold Induced Urticaria
    • Trench Foot
  • Cold Injury Mimics
    • Pressure Necrosis including Acute Compartment Syndrome
    • Cellulitis

Diagnosis

Example of stage 1 appearance of trench foot[12]
  • History
    • Diagnosis is clinical
    • History of exposure to wet cold for at least several hours in temperatures near freezing
      • Or an exposure for days with higher temperatures, as high as about 15 °C
    • History of losing feeling for at least 30 min and having pain or abnormal sensation on rewarming
    • Most commonly occurs in the feet, but can occur elsewhere in the body, including hands
  • Physical Exam: Physical Exam Foot
    • Red, edematous hands or feet
    • Demarcations are not sharp between diseased and non-diseased tissue (unlike frostbite)
  • Special Tests
  • The diagnosis of NFCI is made clinically
  • Imaging and laboratory testing are not helpful in most cases

Classification

  • Stages of Trench Foot[13]
    • Length varies widely
    • Some stages may be very short, easy to miss
    • Transition times vary
  • Stage 1 (cold exposure)
    • Characterized by complete loss of sensation
    • Patients report numbness, hands or feet feel like blocks of wood
    • May have trouble walking due to loss of sensation
    • Limbs may appear bright red, then become pale or white due to vasoconstriction
    • Stage is painless
  • Stage 2 (pre-hyperemic or post-exposure)
    • Starts when the victim is rescued from cold, placed in warm environment
    • Takes place during and following rewarming
    • Duration is extremely variable (hours to days)
    • Light skin: appears mottled and pale blue, indicating mild return of circulation
    • Dark skin: difficult to see color changes
    • Pulse is weak, but may become strong later, slow capillary refill
    • Limb is cold and insensate, with or without swelling
  • Stage 3 (hyperemic)
    • Starts suddenly then persists for days or weeks
    • Limb is bright red, swollen with strong pulses
    • Capillary refill remains delayed due to injury to the microcirculation
    • Hyperalgesia replaces numbness, although some distal areas may still be diminished or insensate
    • There is usually no tissue damage
    • Blisters may arise in injured areas that have suffered pressure injury or infection.
    • Blistering or discoloration may signify incipient necrosis.
  • Stage 4 (post-hyperemic)
    • Last for weeks to years or be permanent
    • Appearance is normal except in rare cases where tissue has been lost
    • Limbs are cool and are usually exquisitely cold-sensitive, vasoconstrict when exposed
    • Limbs may stay cold for hours, even after very brief cold exposure
    • Chronic pain in response to cold is common
    • Hyperhidrosis: often complain of excessive sweating
    • Victims may develop symptoms that resemble complex regional pain syndrome (CRPS)
    • Amputation is rare, but can occur with tissue necrosis

Treatment

Prevention

  • Primary treatment is prevention
    • Not well studied or published
  • General
    • Avoid wet-cold environments
    • Some recommendations are from warm water immersion injuries
    • Clothing should be warm, even when wet
    • Material: Synthetic materials are preferred over wool, avoid cotton as it gets very cold when wet
    • Remain active to encourage circulation
    • Elevate feet when possible
    • Education and training for cold to prevent, minimize stress and risk
    • Rotate personal in and out of cold environments
  • Dry feet
    • Air dry feet >8 hours a day is effective in preventing warm water immersion foot
    • Recommend to dry feet for a day after every 2 days of immersion[14]
  • Soldiers guide from WWI[15][3]
    • Paired with battle buddy, responsible to check each others feet
    • Increase rations, provide dry socks in waterproof bags
    • Change socks regularly, keep warm, avoid friction blisters
    • Inspect for blisters, signs of gangrene
    • Raise feet to prevent venous edema
    • Rotation schedules to avoid prolonged periods in wet, muddy trenches
    • Wraps around the calf and ankle above boots
    • Remain as active as possible to prevent vasoconstriction
    • Gum boots with foot powder instead of using oils (which probably increaser risk)

Prehospital

  • Patient moved to warm environment quickly
  • Patient may need to be carried
  • Wrapped in vapor barrier with insulation, over wet clothing as needed
    • Can remove wet clothing in warm environment

Emergency Department/ Acute Management

  • Correct hypothermia, if present
    • Use core temperature to identify
  • Rewarming limbs
    • If frostbite is present, rewarm affected limbs in water at 37-39 °C
    • If frostbite is absent, limbs do not need to be rewarmed
    • Rewarm gradually with rest, elevation, gentle pat drying
    • Rapid rewarming can cause severe pain, increased oedema, and increased tissue ischemia
  • Hydrate to address fluid losses
    • Recommend warming to ~42 °C
  • Avoid
    • Rubbing affected limb due to damaged skin
  • Tetanus Booster should be administered
  • Antibiotics are not routinely needed
  • Pain control
  • Consider prophylaxis for Venous Thromboembolism

Hospital Management/ Acute Management

  • Limb care
    • Elevate above level of heart
    • Dressings, if necessary, should be loose to protect circulation
  • Stage 3/ hyperemic
    • Sensation returns, limb becomes hyperalgesic
    • Recommend cool limbs using a fan at room temperature to 15-18 °C
    • Analgesics are generally ineffective including opioids
  • Amitriptyline
    • Initiate at the onset of pain[16]
    • 50 to 100 mg orally at bedtime
    • Higher doses for breakthrough pain
  • Gabapentin
    • Can be added or substituted if Amitriptyline is insufficient
  • Mild fever in the first 12 to 36 hours is common and usually transient
  • If cellulitis is present, antibiotics to cover staphylococci, streptococci, and pseudomonas
  • Surgical consultation if there are signs of tissue necrosis (hemorrhagic blisters)
  • Not helpful
    • Vasodilators including Nifedipine

Long Term Care

  • Pain management
    • Neuropathic pain and CRPS are common
    • Often require pain management specialist
  • Occupation
    • Outdoor work only if minor symptoms without numbness
    • Some soldiers can return to full duty if the normal response to cold
  • Peripheral neuropathy
    • Should see a neurologist for further investigation
  • Prostaglandin Analogue
    • Iloprost (a synthetic prostaglandin I2 analog), temporarily reduced pain and increased mobility in a case report[17]
  • Nicotine tartrate
    • Demonstrated improved symptoms in 16 (44%) of 36 patients, with particular improvement in pain, paraesthesia, and exercise capacity.[18]
  • Ineffective drugs
    • Aminophylline
    • Papaverine
  • Future research
    • Thromboxane and prostaglandin inhibitors have shown increased tissue survival in frostbite[19]
  • Tinea Pedis
    • If present should be treated with systemic or topical antifungals

Operative

  • Indications
    • Unclear
    • Recommend surgical consult if evidence of significant necrosis
  • Technique
    • Lumbar Sympathectomy (obsolete, not recommended)

Complications 

Complications

  • Acute tissue necrosis
  • Infection
  • Difficulty ambulating
    • Patients may have a ‘slapping, flat-footed, springless gait’ which often resolves in about 1 week[20]
  • Cold feet
    • Limbs often feel cold with persistent vasoconstriction, especially after cold expsure
    • This can cause pain, even when walking
  • CRPS/ Chronic Pain/ Hyperalgesia
    • Occurs frequently
  • Nail pathology
    • Intermittent nail loss
  • Severe arthropathy of major joints
  • Hyperhydrosis
    • In response to cold, heat, or emotional stimuli
    • Can lead to recurrent Paronychia, Onychodystrophy
  • Raynauds Syndrome
  • Chronic fungal infections
  • Psychiatric/ behavioral
    • Including Depression, suicidal thoughts
    • Substance and alcohol abuse
  • Occupation
    • Inability to work outdoors
    • Soldiers may be unable to redeploy
      • In one study, NFCI was career ending for 25/42 soldiers and career altering for the remaining 17