Preventive Medicine for Providers in High-Threat Environments

It can be said that the primary role of any tactical emergency medical support (TEMS) provider is to render aid so that others may remain in the fight. Mission success is the ultimate goal, and so much of that depends on the ability of the operators to participate effectively and, if injured, minimize the burden placed on the other team members. This chapter will focus on the area of preventive medicine for those who respond to emergencies in dangerous environments. Preventive tactical medicine (PTM) incorporates ideas from military medicine, international and humanitarian relief, epidemiology, infectious disease, and wilderness medicine. Incorporating these concepts into the regular maintenance and training of a team of operators will ensure that those members selected for a given mission will start at the best baseline health possible and thereby will have the highest probability for operational success.

Historical perspective

Preventive medicine has long had a role in the military. Periods of advancement in battlefield medicine and trauma surgery have routinely paralleled the involvement of the United States in foreign military actions. It is well described that the field of emergency medical service(s) (EMS) has incorporated lessons and concepts developed during wars to improve domestic medicine, both through medical care as well as means of transport of the sick and injured. In a similar fashion the U.S. military medical community has improved their protocols for preventive medicine during these periods of intense and rapid adaptation to the dangers of enemy forces in hostile environments.

Disease and nonbattle injury (DNBI) is a term used by the U.S. Army to describe what practitioners in the civilian world simply call “illness” and is the primary cause of missed workdays in the military. In this realm there are two major goals: health of the individual patient and success of the unit’s mission. A healthy team of operators primed for success is one who begins a mission at baseline health without impairment from medical illness or medicine, mental illness, deconditioning, preexisting injury, high-risk chronic disease, incomplete vaccination status, or lack of clarity regarding local health threats. A solid knowledge of how to prepare a medical threat assessment (MTA) includes understanding the concepts of PTM. And although the TEMS provider typically does not have rank or authority within the team, he does serve as the “medical conscious” to the commander, and medical readiness recommendations on behalf of each soldier should be provided when necessary.

Current practice

Operator Selection

For a special weapons and tactics (SWAT) or special operations team to remain vigilant, ready to rapidly deploy, and formidable, each member must be healthy and unrestricted by preexisting medical conditions. For the good of the mission, operators chosen for teams should be very healthy at baseline, and exclusion criteria should be clear and obeyed. The maintenance of individual health is the key to team health. The U.S. Army uses specific criteria for the selection of general soldiers, and there are numerous disqualifying medical conditions for enlistment. A subsection of the document discusses the particularly stringent health requirements to be considered for special operations. Many police organizations use similar screening processes to disqualify candidates applying for employment, maintenance of job readiness, and for selection to special operations teams.

At this time there is no national standard of disqualifying medical conditions for the selection of police special operators, although recommendations have been made. Thus it is the responsibility of each department to decide which individuals are medically suited to fulfill particular job requirements. Such guidelines are used to evaluate each candidate to determine suitability before training. Conditions are divided into two types based on the extent to which the condition affects an individual’s ability to perform essential functions of the job. The first precludes an individual from performing the essential functions of the job and disqualifies a candidate from the selection process. The second is a medical condition that based on its severity may or may not preclude an individual from performing the essential functions of the job.

The most effective preventive medicine program begins with constructing a team of officers who meet the rigid medical standards and are therefore at low risk of missing workdays or compromising a mission due to a preexisting condition. There are absolute contraindications, such as hearing loss, vision impairment, cardiac conditions, and amputated fingers. Just as those pilots chosen for military duty have specific medical ailments that will preclude them from flying duty, job-specific standards for law enforcement SWAT teams should focus on preventing potential crises. For example, should SWAT officers develop diabetes mellitus, their ability to perform extended missions without refrigeration and regular meals would be severely compromised, and they should be removed from operations secondary to the resulting personal and team risks. This could similarly apply to those afflicted with conditions such as asthma, alcohol dependence, seizure disorders, symptomatic cholelithiasis, and a plethora of other diseases. Selection of team members with nondisqualifying medical conditions, such as essential hypertension, should take place with the caveat that the operator has access to and is able to carry and take necessary medications regularly on sustained operations. Those with environmental allergies (e.g., anaphylaxis to bee stings) should be approved with caution, and consideration should require desensitization therapy as well as availability of antidotes. Even seasonal allergies must be considered particularly because sedating antihistamines should be avoided for all nonemergencies in the tactical environment.

Mental health disorders warrant special discussion here. The Global War on Terrorism has shed new light on the seriousness and incidence of posttraumatic stress disorder (PTSD), which in previous decades has gone by several names: hysteria, soldier’s heart, irritable heart, shell shock, combat fatigue, stress response syndrome, Vietnam veterans syndrome, and ultimately PTSD. This disorder is, unfortunately, not uncommon after combat. It is critical for the military and for law enforcement agencies to conduct thorough and exhaustive psychological testing for recruits before selection because we have learned now that the fear and stress caused by combat has the ability to worsen preexisting mental illness and may not only compromise the team and mission but also cause permanent problems for the individual. The U.S. military has strict standards regarding mental illness as exclusionary criteria for enlistment, as noted in the 2011 Standards of Medical Fitness, which defines nearly any preexisting mental health disorder, from attention-deficit disorder (ADD) requiring medication to depression to nocturnal enuresis after age 13, as disqualifying features. Law enforcement agencies should consider similar standards.

Health Maintenance

Following the selection process the key concept in preventive medicine for responders in high-threat environments is general health maintenance. Physical standards should exist to remain on a team, and these should be tested on a regular basis. Each person on the team needs to remain physically fit in order to prevent injury and to ensure the team operates at its peak. Fitness includes not only strength-training and bodybuilding exercises but also regular physical conditioning with stretching and aerobic and anaerobic exercises. Although prevention of deconditioning is paramount, proper nutrition and maintaining a healthy weight with a low total body fat index are also vital. , In order for a unit to function at maximum capacity the team leader or medical officer should ensure all individuals are taking their home medications, receiving regular physical examinations/treatments, and receiving counseling on smoking cessation and drug and alcohol use. Drug and alcohol dependence, although uncomfortable topics for many, must be addressed within the team and should function as automatic disqualifiers from special operations. All efforts should be made to provide treatment and reinstatement, if possible.


Immunizations are another important aspect of health maintenance for disease prevention and team health. The Department of Defense requires certain immunizations for military personnel and most civilian employees. These include the following, and some are location specific: anthrax, hepatitis A/B, pneumococcus, meningococcus, measles, pertussis, smallpox, diphtheria, typhoid fever, yellow fever, mumps, polio, rabies, rubella, varicella, tetanus, adenovirus types 4 and 7, Haemophilus influenzae serotype B, influenza, and Japanese encephalitis. There are certain individuals who are unable to tolerate vaccines, such as those with egg allergies. The CDC provides a concise summary to help guide physicians in this matter and can be referenced on their website at . Immunization policies should be in place for all teams functioning in foreign countries.

Medical Threat Assessment

After team selection, immunizations, and health maintenance have been addressed, team leaders must prepare for individual missions. Part of that preparation is performed by the medical team or TEMS provider and is called an MTA. The MTA is an all-hazards approach evaluation tool that provides a standardized mechanism for identifying and risk stratifying potential threats to the health and safety of those involved in the mission. It is a flexible framework for information collection and can be used as a checklist to ensure that preventive medicine measures are completed during the planning phase. An MTA should be performed as far in advance of a mission as possible and should address environmental risks and available assets. Failure to perform a proper MTA could leave the team unprepared for climate extremes, weather, local flora and fauna, local infectious disease risks, and problems with food and water.

Environmental Exposure

Location of missions must be taken into account when considering threats, such as cold and heat extremes, environmental moisture, and sun exposure. Environmental injury can hinder a team’s effectiveness and pose severe health threats.

During cold weather missions the primary preventive medicine concerns regard frostbite and hypothermia. It is important for team members to be outfitted with appropriate clothing, gear, water availability, and protection. Hypothermia occurs when the body loses heat faster than it is able to generate it. Core body temperature falls below normal, typically defined as a core temperature below 95 °F. It is critical to understand that freezing environmental temperatures need not be present for hypothermia. It tends to occur during cold, windy weather, rapidly changing weather environments, and in those who are wet, exhausted, and poorly dressed. Prevention includes proper clothing, staying dry, avoiding wind, getting rest, and monitoring your fellow team members. Operators are very likely going to be wearing heavy gear and armor that will lead to perspiration. Sweat will lead to evaporative and conductive heat loss and significantly increase the risk of developing hypothermia. Proper head coverage is essential. The TEMS provider must help team leaders to remember work-rest cycles on sustained operations and has a responsibility to ensure that operators have a place to rewarm periodically. These cycles are particularly important for those with extended exposure roles, most notably snipers, spotters, and countersnipers. Warm drinks should be made available if possible. Critically the prevention of a team philosophy of “toughing it out” will help assure that members in need of help will ask for it.

Frostbite occurs at temperatures below freezing in those who are wet, underprepared, and poorly dressed. Frostbite injuries occur on a spectrum from superficial injury to severe, full thickness skin injuries, which can lead to loss of limb or extremity. For the purposes of tactical medicine, recognizing the early stages, known as frostnip, allows the TEMS provider to perform actions to reverse the condition before development of true frostbite.

Frostnip is a superficial, nonfreezing cold injury associated with intense vasoconstriction on exposed skin, usually cheeks, ears, or nose. By definition, ice crystals do not form in the tissue nor does tissue loss occur in frostnip. The numbness and pallor resolve quickly after covering the skin with appropriate clothing, warming the skin with direct contact, breathing with cupped hands over the nose, or gaining shelter that protects from the elements. No long-term damage occurs. The appearance of frostnip signals conditions favorable for frostbite, and appropriate action should be undertaken immediately to prevent injury.

Frostbite occurs when tissue freezes, forming intracellular ice crystals and leading to variable degrees of tissue damage. Although outside the scope of this chapter, there are well-defined degrees of frostbite that correlate somewhat to the better-known descriptions of the severity of burns. Contributing factors to frostbite include the amount of tissue exposed, ambient temperatures, nutritional status, wind chill, nicotine use, previous cold injury, physical activity, and tight-fitting clothing or boots. Severe frostbite can require evacuation for hospital evaluation and result in loss of a team member.

Immersion injury, such as trench foot, can occur during extended operations as well. This disease process was defined during World War I and is caused by prolonged exposure to dampness and cold temperatures. Improper footwear and hygiene are the primary preventable risk factors. The ambient temperature need not be below freezing. 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. In severe cases, untreated trench foot can involve the toes, heel, or entire foot. , Preventative measures, such as waterproof boots, dry socks, massage, and early recognition, are key.

Heat injuries are a serious concern during prolonged operations in warm climates. In hot environments body temperature increases, which places stress on the body’s ability to regulate temperature and can lead to failure of compensatory mechanisms in the body. High humidity interferes with sweat evaporation, leaving radiation of heat as the primary method of cooling. The layers of gear and heavy equipment required in tactical operations reduce the ability to radiate heat to the environment and block wind-driven convection heat loss, adding to the cumulative heat stress and thus increasing the risk of heat injury. By overwhelming the body’s ability to maintain temperature equilibrium, heat illness can occur. The spectrum of disease includes heat cramps, heat exhaustion, and ultimately heat stroke. It is very important for tactical teams to prevent heat-related illness, starting with the MTA consideration of environmental temperature, humidity, and air movement. Prevention of temperature-related injury involves reducing exposure times, work-rest cycling, heating or cooling areas for operators, moisture-wicking base layer garments, and adequate hydration. It is critical that officers feel comfortable informing their commander if they develop early temperature injury to prevent progression to more severe forms. Lastly, overexposure to ultraviolet (UV) light from the sun can lead to sunburn and also contributes to heat injury. Use of high sun protection factor (SPF) sunscreen before deployment and reapplying often can prevent sunburn. Finding shade when available will also reduce UV burden and lessen the individual’s heat stress.


Dehydration occurs when fluid losses exceed intake. Those under high stress and in warm environments lose most of this fluid through sweating but also through insensible means, such as respiration. Heavy gear and hard exertion can lead to fluid losses of 1 L/h. Replacing lost water is necessary in order to maintain an adequate hydration status and avoid heat injury. Any exposed operator is at risk, and command-driven oral hydration should be mandated by the commander and TEMS provider. This is primarily important because unfortunately thirst is not the ideal indicator of hydration status. Headache is a likely first indicator of dehydration and must be addressed as such. Preventive medicine dictates that all team members prehydrate and carry adequate supplies on their person, typically in the form of a backpack bladder. Rehydration with water or 0.5- to 0.25-strength diluted sports drinks will work for minor cases of dehydration, and the dilution will prevent the gastrointestinal (GI) upset sometimes seen with heavy carbohydrate drinks. Although weather conditions and individual variation in sweating may dictate different fluid requirements, a safe recommendation is 1 L/h of work, and the urine color concentration can be used as a rough guide for hydration status.

Infectious Diseases

In the tactical environment the most likely infectious diseases to be encountered are those transmitted by insect vectors. For missions within the United States the greatest risks for mosquito and tick-borne illnesses are West Nile virus and Lyme disease, respectively. However, other tick-borne illnesses, such as babesiosis and rickettsial Rocky Mountain spotted fever, are also important diseases to consider when operating in endemic areas. American trypanosomiasis, also known as Chagas disease, is a protozoal disease caused by transmission from the bite of the “kissing bug” found in the southern United States and Latin America.

Because of the variable incubation periods of vector-borne diseases, acute transmission of these diseases are unlikely to take an operator out of action during a mission. But that does not obviate the TEMS provider of the responsibility of making sure team members undergo proper evaluation for these infections if symptoms develop days or weeks later. All of these diseases can lead to significant impairment, including fevers, encephalitis, myocarditis, neurologic impairment, or sometimes death. The best treatment is prevention. Team members should prepare appropriately with protective clothing, application of high concentration N , N -diethyl-meta-toluamide (DEET) to all exposed skin, and using appropriate pest control with netting and sprays at home base.

Viral infections typically cause self-limited disease; however, more significant infections leading to influenza, measles, hepatitis, and weaponized smallpox could possibly occur. Fortunately vaccination has helped to decrease the risk of infection with hepatitis A, hepatitis B, influenza, measles, poliomyelitis, rabies, smallpox, and mumps when exposed. But, in an era where fringe thinkers are increasingly choosing to ignore science and forgo vaccinating their children, it is imperative that operators stay up to date with immunizations. Adenovirus is very contagious and leads to a spectrum of respiratory illnesses. However, vaccination in some populations and good hygiene in close corridors can prevent the spread of disease. Similarly many viral infections can lead to gastroenteritis, with diarrhea and vomiting, which can ultimately cause dehydration and impair the ability to fight. Good hygiene, including proper toileting away from camp and waste disposal, is a critically important piece of disease prevention.

Bacteria can lead to severe infections and often do not resolve without proper treatment with antibiotics. Since the terrorist attacks in the United States, anthrax has become a true terrorist threat. It is a spore-forming bacterium leading to cutaneous, GI, or inhalational infection. Vaccination in the appropriate population helps to prevent infection when exposed. In addition, caution with human and animal blood and bodily fluids and disinfection of the premises are important aspects in avoiding the spread of disease. , Bubonic plague, a zoonotic bacterial infection caused by Yersinia pestis , is transmitted from rodents via a flea vector and is endemic to parts of the southwest United States. The more deadly pulmonary form, called pneumonic plague, is transmitted person to person by droplet inhalation. Vaccination does not protect against pneumonic plague but can help prevent contraction of the bubonic form from fleas. Other preventative measures include pest control, avoidance of dead animals, and protective gear. , Tetanus, a neurotoxin-based illness caused by the spore-forming bacterium Clostridium tetani found in soil and animal GI tracts, is introduced through contaminated wounds and infection and leads to acute, lethal central nervous system disease. Cleaning wounds and maintaining current immunizations is an important aspect of prevention of tetanus.

For tactical operational teams, such as military special forces or groups deploying for disaster response internationally, additional region-specific illnesses must be considered which can cause significant morbidity and mortality. Malaria is a potentially lethal protozoal infection endemic to tropical and subtropical areas and is caused by species of the Plasmoidium genus. It is widespread across developing countries, particularly in Africa, and is transmitted by Anopheles mosquito bites. Symptoms vary but typically include fever, chills, myalgias, abdominal pain, and diarrhea. Prophylactic medications, such as mefloquine, Malarone, and doxycycline, can help prevent infection while in these areas and should be mandatory for all operators before travel and after return.

Dengue fever is a viral infection spread via mosquitos in tropical urban centers. Infectious symptoms include fevers, headaches, myalgias, hemorrhage, and sometimes shock or death. Prevention is similar to avoiding other mosquito-borne illnesses but typically involves the avoidance of outdoor activities while mosquitos are active and using protective clothing, nets, and DEET spray. ,

Yellow fever virus causes a viral hemorrhagic fever and is endemic to tropical jungle environments in Africa and South America. Prevention with immunizations and boosters are important and should be given before travel to any endemic area because the mortality rate for unvaccinated patients is as high as 50%. Another infection, typhoid, is caused by Salmonella typhi and is spread from human to human via fecal contamination and shared food. It causes a febrile illness characterized by abdominal pain and sometimes rash. It is encountered both domestically and abroad, typically when exposed to contaminated drinking water in developing countries. Vaccination is available. Otherwise, preventive measures include properly cooking and washing food, drinking appropriate water, and practicing good fecal hygiene.

Parasitic infections are typically contracted through contact with or ingestion of contaminated water. The most common infections include amebiasis, ascariasis, giardiasis, and schistosomiasis, all of which can lead to significant diarrhea, abdominal pain, and in some cases liver failure or death. Prevention with filtering water, boiling water, good hand washing and hygiene, avoidance of fresh water, and safe food preparation is vital. Domestic tactical operations are typically short in duration, close to urban centers, and well within reach of clean water and sanitation. In other operational environments, such as disaster deployment and military missions, these illnesses may be encountered and should be part of the MTA.

Tropical environments lend themselves to more exotic animals and exposure risks. Within the United States the vast majority of poisonous snakebites are caused by pit vipers, such as rattlesnakes, copperheads, and cottonmouth snakes. However, most deaths within the United States are caused by diamondback rattlesnakes. There is a correlation between envenomation dose and rapidity of onset of illness. Symptoms can range from mild swelling of the extremity with localized pain, to diarrhea, confusion, and severe cardiovascular collapse and shock. Prevention includes appropriate leather boots and situational awareness. In the case of envenomation the TEMS provider should arrange medical evacuation to the nearest hospital for supportive care and antivenin, as needed. Venomous spiders, which in the United States are primarily the infamous black widow spider and the brown recluse (“fiddleback”) spider, which are the only two endemic species capable of human envenomation, are rarely life or limb threatening. The black widow produces a painful bite and injects a neurotoxin. The brown recluse bite is typically painless, and the necrotoxin injected can cause variable degrees of tissue loss from small ulcers to loss of fingers or toes.

Preventive medicine is a key concept to be understood by all practitioners in the tactical medicine realm. Similar to military and flight medicine, TEMS providers are the medical conscious of the team and for the commander. As such, it is the responsibility of the team’s medical expert not only to respond to injured officers, suspects, and civilians but also to engage the team in the important concepts of preventive medicine. In doing so the provider helps to ensure that the operators are in peak fighting condition and are able to participate safely in the mission at hand. Ensuring that each member is screened appropriately before acceptance to the team and before each relevant mission maximizes the probability of mission success and safe return of each participant.

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Aug 25, 2019 | Posted by in EMERGENCY MEDICINE | Comments Off on Preventive Medicine for Providers in High-Threat Environments
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