Mark: “I sat down and Tjar and Dave helped me to take off my shoes at the finish line. When I stood up to take off my rain pants I started crying and shaking because of the pain that I felt in my feet. I collapsed in the arms of the medical team. I had terrible macerated, trench foot.”

Immersion foot syndromes

A trench foot is an immersion foot syndrome. These syndromes refer to foot injuries due to non-freezing cold and wet exposure or to foot injuries due to prolonged immersion in warm water.

Non freezing cold injury (NFCI)

Depending on the situation that caused the injury different names are used for related conditions : “trench foot “, “immersion foot”, \”seaboot foot”, or “shelter foot”. NFCI can occur in the feet as well as in the hands. Extremities are art risk when they are cold ( 0° to 15°C) and wet for prolonged periods of time. Cold alone is not sufficient to cause NFCI. The duration of an exposure to cold and wet conditions to cause NFCI is not known. Individuals at risk are soldiers, homeless people or hikers.

Pathophysiology

The pathophysiology of NFCI is poorly understood. It includes impaired control of the circulation, direct damage to the microcirculation and probably damage to the nerves. Tissue loss is not a feature of NFCI but likely due to pressure injury such as walking long distances on NFCI affected feet.

NFCI progress through a series of stages:

The first stage during cold exposure is characterized by loss of sensation usually taking the form of complete anesthesia. The patient sometimes describes the feet as feeling like a block of wood. He/she becomes clumsy and may have difficulty walking. Extremities may be bright red at first but then become pale or completely white.

The second stage begins as the patient is removed from the cold environment and lasts a few hours. The extremities become a mottled pale blue, pulses become bounding, but capillary refill is delayed. Swelling can occur. The extremity continues to be cold and numb and the patient may still have problems walking.

The third stage is characterized by the abruptly beginning of hyperemia. It may last for days to weeks. The affected extermity becomes bright red and edematous and anesthesia is replaced by intense pain.

The fourth stage follows the period of hyperemia and may persist for years or even be permanent. The affected extremities are cool and very sensitive to cold .The majority of patients may have chronic pain usually in response to cold.

Diagnosis

The diagnosis of NFCI depends on a history of prolonged exposure to cold ( generally 0° to 15° C), wet conditions and clinical findings consistent with the four stages of injury. The primary alternative diagnosis is frostbite.

Management

In the prehospital setting: get the patient to a warm environment, if possible don’t allow him to walk. Remove wet clothing once the patient is sheltered. If systemic hypothermia and/or frostbite is present take care of these situations first.

In the emergency department: allow the extremities with NFCI to rewarm gradually with bed rest, elevation of the legs and air drying at room temperature. Replace fluid losses, give analgesia. Tetanus prophylaxis is recommended. There is no role for prophylactic antibiotics.

Inpatient management: continue any necessary emergency treatment (rewarming, rehydration). Optimize pain treatment using NSAID’s, opioids, amitriptyline (50 to 100 mg orally at bedtime) or neuropathic pain medication such as gabapentin.

Short-term complications of NFCI include gangrene, infection, gait disturbance, and hyperalgesia. Long-term complications are due to peripheral neurovascular injury : the areas affected feel cold, experience prolonged episodes of vasoconstriction especially after re-exposure to cold. Re-exposure commonly causes pain. Pain may also be provoked by walking. Ulceration and nail loss can occur intermittently without provoking injury.

Prevention

Measures that may be used to reduce the risk of developing NFCI include: avoid cold/wet conditions, wear clothing that provides thermal protection but is not constricting, change socks regularly, stay active and avoid malnutrition, dehydration and fatigue.

\”Mark luckily had a mild form of trenchfoot. After a few hours of rest, rewarming of his feet, eating and drinking and taking some painkillers he was able to perform some steps very carefully. The following days he recuperated completely.\”

Mark is a ultrarunner who ran his first non stop 160 km during the Bello Gallico event in December 2017.

Reference: UpToDate: NFCI