Military Dermatology: Cold Injury

We continue to publish the chapters of the Textbook of Military Medicine textbook on military dermatology, which were presented to the editors by Tatyana Svyatenko, Professor of the Dnipro Medical University, Doctor of Medical Sciences, member of the EAHV. (Source: Military Dermatology . Translation: Galina Prit. Photo by Specna Arms on Unsplash.)

INTRODUCTION

History has demonstrated that cold strikes can lead to losses in combat troops that can exceed losses in combat. Proper training of our combat forces, combined with proper provisioning and planning, can minimize casualties from cold wounds. Good planning requires asking a number of questions.

• What weather conditions and the intensity of the battle will be?
• Are there enough supplies such as food and clothing?
• Have officers and soldiers been trained in the prevention of cold injuries?
• Do commanders have enough troops for frequent rotations to the front line?

Cold defeats are most often associated with front-line infantry - the most valuable army resource. These injuries often require months of rehabilitation or result in permanent disability. Since a large number of cold injuries usually only occur during war, precise treatment protocols have not been developed and further research is needed. Early recognition of signs and symptoms and prompt treatment are critical. The training of healthcare workers and education in the recognition and treatment of diseases caused or exacerbated by cold should be a priority. Line officers also need our help as medical advisers to implement adequate preventive measures and ensure that troops return to duty quickly.

A LITTLE HISTORY

Cold injuries have meant a lot for the loss of combat capability of armies of different times, starting from ancient history. Frostbite is mentioned in the works of Hippocrates, Aristotle, Galen. Other historical records have documented the emergence of significant cold injury problems among the Greek armies of the late 4th and early 3rd century BC.

During the American Revolution, James Thatcher described severe losses from a cold injury in 1777: an army of 10,000 lost 2,900 men in action. Even then there was a certain understanding of the pathogenesis of cold injury. Benjamin Rush, chief medical officer at military hospitals, wrote in a small pamphlet with instructions for maintaining the health of soldiers: “The commander must make every effort and ensure that the soldier never sleeps, or at least sits in his tent in wet blanket or damp straw. Maximum vigilance is needed to avoid this powerful source of disease among the soldiers.

Baron Larry, surgeon to the French army in the Napoleonic Wars, described frostbite and "freezing" as important causes of the defeat of the army in Poland in 1812. He also noted that "General medicine must always precede surgical intervention" and described the disastrous consequences due to sudden danger . bodies by the fire.

The Crimean War (1854–1856) had an impact of proper training and equipment on the number of casualties from the cold. During the first winter (1854-1855) English troops fought in trench wars with static defensive positions. The soldiers were inexperienced and unfamiliar with the potential dangers of cold weather. They were also hampered by the lack of proper food and clothing and the debilitating effects of diarrhea and dysentery.

With fewer than 50,000 soldiers, 1924 cases of cold injuries were reported, 457 deaths - 23.8% of the total number of cold injuries. During the winter of 1855-1856. there were only 474 cases of cold injuries and 6 deaths (1.3%). Meteorological conditions and precipitation were essentially the same in both winters. But during the second winter, the troops had much better living conditions, along with improved winter clothing and sufficient food. The average soldier was hardened and knew how to take better care of himself and prevent cold injury. In the Franco-Prussian War of 1870, 1,450 cases of severe frostbite occurred among 92,067 Prussian soldiers. During the Russo-Turkish War (1877-1878) 4,500 frostbite victims are reported, representing 1.5% of the 300,000 troops in Bulgaria and 5.1% of the 87,989 evacuated casualties.

British medical observers from the Japanese army made detailed reports for January 25-29, 1905 during the Russo-Japanese War. Of the 7742 casualties, 505 fighters were hospitalized with frostbite, the ratio of frostbite to combat injuries is approximately 1:15. Toes were affected in 67% of cases of cold injuries, fingers - in 28% of cases. Injuries were minor and amputation was rarely required. During the next battle, British observers noted that Japanese troops were given extra socks and rations. During marches, stops were made to remove boots and replace them with Chinese felt or straw boots. The number of victims of frostbite was drastically reduced to only 70 soldiers hospitalized for cold injury.

The most detailed history of cold injuries among combat soldiers comes from the First World War. The British experience is most common, and the losses in the US were less due to the experience gained in their participation in the war. In addition, most trench warfare for US forces took place during periods of the year when the effects of cold and moisture were not significant. The lessons of World War I were forgotten and the United States suffered many casualties in World War II before the problem was taken seriously again. Cold injuries range from frostbite at high altitudes to trench (or trench) foot and so-called plunge foot lesions suffered by ground forces during the Mediterranean and European marches to the Aleutian Islands. Lessons learned in one case, unfortunately, have not been fully utilized in others.

HEAT CONSUMPTION MECHANISM

Cold injury is tissue damage resulting from heat loss from exposure to cold. This loss can occur through several mechanisms: conduction, convection, radiation, evaporation, and respiration.

Conductivity

Heat loss due to conduction is the loss of heat through direct contact with a cold object. This variant is rare, but can be a serious source of injury. Contact with cold metal is a common injury. Liquids such as gasoline and other solvents cause rapid evaporative cooling due to the low freezing point, which can result in instant frostbite on contact at temperatures below freezing. Heat loss by conduction can occur 32 times faster in water than in air. The moisture source can be sweat, water, or other liquids.

Convection

Loss due to convection occurs when air currents dissipate through a thin layer of warm air around us. The body, hair, and clothing help maintain this warm air layer. Wind cooling is important because the greater the wind speed, the faster the protective layer of warm air is removed.

Radiation

Radiation of heat comes from exposed surfaces of the body. Most often, these are the most exposed areas of the body: hands, face, head and neck. At approximately 4°C, 50% of body heat can be lost from an uncovered head; at sub-zero temperatures, this loss can increase to 75%. Proper headgear helps increase body temperature by reducing heat loss; Removing headgear during strenuous exercise can increase heat loss by soldiers.

Evaporation

Evaporation, which occurs when water vapor is released from the skin, is an important form of heat loss. Clothing that allows water vapor to escape helps keep you warm, as damp skin requires increased heat loss to dry the skin. This heat loss preserves life in hot climates, but is detrimental in cold environments.

Breath

Breathing is an additional source of heat loss and the result of exhalation of humidified, warm air. Heavy physical activity leads to accelerated breathing and significant loss of heat and water. Covering the mouth with a mask (such as wool) can store some of the exhaled heat and preheat the incoming air.

FACTORS AFFECTING HEAT CONSUMPTION

Many factors can contribute to heat loss and risk of cold injury. This is the degree of cold, the intensity of the battle, protective clothing and others. Combat conditions are often linked to several of these factors and leave military and civilians at high risk of injury from the cold.

Weather and duration of exposure

Short exposures (i.e. just a few minutes) to intense cold, especially high winds, humidity, or contact with metal or volatile solvents, can lead to frostbite, while prolonged exposure to slightly higher temperatures promotes trench foot, dive foot, and pernio. The average duration of exposure leading to frostbite is 10 hours. During the Korean conflict, 80% of cases in 1950-1951 reported exposure durations of 12 hours or less, with a range of 2 to 72 hours, lasting 14 days (average 3 days).

Type of fighting

Actively defending units during an attack are at the greatest risk of cold injury. Static situations do not allow movement and lead to prolonged exposure. Active combat and defense increases fatigue and often prevents them from warming up, changing clothes, and eating properly.

clothes

Modern cold weather clothing is based on the principle of "layering" and uses a wind-resistant and water-resistant outer layer. Several layers of loose clothing take advantage of the insulating properties of the dead air. This rule also applies to footwear, which must be sized to allow thick socks to be worn without constricting blood circulation and at the same time waterproof. As physical activity increases, clothing layers must be easily removable to allow for heat loss equal to increased performance.

Wearing or not wearing a hat, as noted earlier, can make a significant difference. The new vapor-permeable outerwear allows moisture to be wicked away, helping to maintain the garment's insulating capacity. Finally, gloves provide better protection than gloves because the separate finger slits in the gloves increase the heat loss of the surface area.

Other factors

Some other factors can greatly increase your risk of cold injury:

• older people are more susceptible to cold injuries;
• prior injury from cold leads to re-injury;
• fatigue leads to lethargy, improper dressing, and neglect of hygiene (eg, keeping feet dry);
• lack of proper rotation of troops can increase the risk of cold injuries;
• combat injuries can be complicated by shock and reduced blood flow, which further increases the risk of cold injuries;
• excessive activity leads to excessive sweating and wetting of clothing, which leads to a loss of insulating ability. however, insufficient activity is equally harmful, causing stagnation and lack of heat production.

The pathogenesis of cold injury

For cold injury with subsequent damage and loss of tissue. there are several mechanisms

Cell damage can result from the formation of intracellular ice crystals when tissue freezes. It is believed that other mechanisms of damage are secondary to vascular damage, which leads to impaired microcirculation and tissue hypoxia. This leads to aggregation of erythrocytes and capillary stagnation. In overheated tissue after freezing, irreversible occlusion of small vessels by cell aggregates with the formation of a thrombus was found. In addition, as a result of tissue hypoxia and, possibly, direct exposure to cold, capillary permeability increases with loss of plasma into the extravascular space. This leads to further hemoconcentration, increased viscosity and stasis.

Cold leads to direct metabolic disturbances, negatively affecting sensitive cellular enzyme systems and disrupting cell function. Injuries resulting from exposure to cold can be classified into direct and indirect.

In the next publication, we will consider indirect cold injuries as quite relevant at the present time.