As mentioned earlier, combat operations in Iraq and Afghanistan have provided copious amounts of data to help develop improved transfusion strategies. From the analysis of these two wars, as well as large amounts of civilian data, massive transfusion protocols have been developed which provide for earlier transfusion of fresh frozen plasma and platelets, with improved mortality.9 The military continues with its civilian colleagues to determine the optimum transfusion strategy. Is it ratio driven? Is it guided by viscoelastic testing—thromboelastography (TEG) or rotational thromboelastometry (ROTEM)—in which whole blood clotting is examined?10 Military and civilian doctors alike are trying to create rational transfusion strategies which maximally benefit our patients while limiting the inherent risk associated with blood transfusion.
One area where the military differs from its civilian counterparts is the potential use of fresh whole blood. The military often operates in austere environments in which fractional blood components are not readily available, where supply lines are long, and where the limited supply of blood products, if existent at all, may not be adequate to correct the hemorrhagic shock and associated coagulopathy in the casualties present. In these dire circumstances, fresh whole blood (FWB) is an option.11
FWB provides red blood cells (RBCs), clotting factors, platelets, and fibrinogen—all the components which are required to reestablish hemostasis. The blood is warm, thus not contributing to hypothermia, and is more functional, as clotting is not hampered by the loss of factor or platelet activity through cold storage. Additionally, the RBCs in FWB do not have the lessened oxygen delivery capacity from acquired storage lesions.
However, FWB does have disadvantages. Even with rapid testing for malaria, HIV, hepatitis B, hepatitis C, and syphilis, bloodborne transmission is possible. There is a theoretical increased risk of bacterial contamination given the decreased sanitary conditions inherent to most field conditions. Furthermore, given the chaotic situation in which FWB would be required, the chance of clerical error is increased, compounded by the fact that FWB must be type specific. If more than one person requires FWB, this increased risk for clerical error and a transfusion of incompatible blood is increased even more. Another strictly military consideration is that the donor, also a military member, will have a decreased exercise tolerance for a period of time while the body adjusts to the acute, albeit voluntary, blood loss. It must be remembered that in all situations, the success of the fight trumps any individual. Weakening the remaining fighting force is not a decision to be made lightly.
Another facet of military-related injuries involves nonconventional weapons. Unfortunately, with the increased activity of terrorist organizations these attacks have been seen in the civilian sector as well. A strong suspicion and good working relationship with the public health sector can greatly assist in determining if a nonconventional attack has taken place and how best to treat those already affected and prevent others from becoming affected.
A nuclear explosion has all the same explosive causes of injury as a conventional explosive—thermal, blast, and ballistic—with the addition of radiation. Radiation exposure requires decontamination prior to being brought into the medical facility, in the same manner as the safety clearance is performed. Triage is first based on a patient's conventional injuries, and then modified based on radiation exposure.12
Radioactive particles are classified as alpha, beta, gamma, and neutron. Alpha particles can be shielded by a sheet of paper and are harmful if internalized. Beta particles require a thicker material for shielding such as a layer of clothing or a few millimeters of aluminum. These can cause skin burns and are also harmful if ingested. Gamma particles and neutrons destroy living cells and are only shielded by a few feet of concrete or inches of lead. Radiosenstivity is directly correlated with mitotic rate, as only replicating cells are vulnerable to radiation's effects. Less mitotically active cells are affected only when larger doses of radiation are absorbed. Thus, a patient's symptoms can be used to estimate the amount of exposure incurred. Furthermore, these symptoms and their time-to-onset can be used to predict mortality as the adverse effects of radiation following a fairly consistent pattern.
Radiation exposure is expressed in gray (Gy) or rad. One Gy is equivalent to 100 rad which is equal to 1 J of energy per kilogram.13 LD50 is defined as the dose which results in death of half of the people exposed. Exposure of 0.35 Gy can cause transient nausea or headache but is not classified as acute radiation syndrome (ARS). At least 2 Gy are required for ARS to develop.
The hematologic system is affected first with a decline in all cell lines. Radiation exposure affecting only the patient's bone marrow could be latent for 2 to 6 weeks, with the main symptom being fatigue. If there aren't other injuries prompting a medical evaluation, it is possible that medical attention would not be sought, even though it is direly needed. The GI system is affected next. At doses of 6 to 10 Gy, within 2 hours of exposure the patient will have acute-onset cramping abdominal pain, nausea, vomiting, and diarrhea as cells of the GI tract slough. Paradoxically, at doses greater than 10 Gy, nausea is suppressed. Early-onset diarrhea, especially without nausea, is a particularly poor prognostic sign. Neurologic symptoms, mainly ataxia, seizures, dizziness, and disorientation, suggest an exposure of greater than 10 Gy. Cardiovascular collapse occurs with doses of greater than 35 Gy.13
Without supportive care, the LD50 is only 3.5 Gy. Death typically occurs within 60 days as a result of the patient's impaired immunity.13 With supportive care, namely fluids, antimicrobials, cytokines, and transfusion, the LD50 increases to approximately 6 Gy. However, these LD50s are based on radiation injury alone. If a patient sustains additional trauma, the LD50 will decrease in accordance with the morbidity and mortality of the other injuries. Furthermore, while some conventional wounds are allowed to heal by secondary intention after repeated debridement, it is important for wounds in irradiated tissue to be closed primarily within 36 to 48 hours. Wounds in irradiated tissue left open for longer than this time frame serve as a source of infection.12
Treatment of radiation injury is primarily decontamination to prevent continuing exposure and symptomatic relief. Intravenous fluids are provided for hypotension and increased fluid losses from damaged skin and gastrointestinal cells. Antiemetics provide relief from nausea and vomiting, limiting further fluid losses. Lymphocyte counts can be very useful in determining if a lethal dose of radiation was experienced as well as for directing cytokine therapy. If lymphocyte counts are greater than 1.7 × 103/μL, a fatal dose is unlikely. Patients with lymphocyte counts less than 300 to 500/μL can be considered for cytokine supplementation to counteract the radiation's effect on bone marrow. Given these suppressive effects, surgical procedures need to be delayed for weeks if possible, or completed within the first 36 hours. Other supportive measures include potassium iodide to prevent thyroid uptake of radioactive isotopes, chelating agents to bind absorbed metals, and Prussian blue to prevent gastrointestinal absorption of radionuclides.12
The evaluation of patients exposed to radiation needs to involve an accurate assessment of those who have a potential for survival. As a general rule, in any military mass casualty situation, if a patient presents with GI symptoms after radiation exposure their chance of survival is low enough and the anticipated utilization of resources is high enough that they will be triaged to “expectant,” and provided with comfort care measures.
Biological warfare also requires close communication between the medical care providers and public health officials. An attack should be suspected in scenarios with an unusual number of illnesses, unusual presentations, or simultaneous outbreaks, especially of diseases not endemic to the area. Weaponized biological agents can be difficult to identify, treat and isolate if a high index of suspicion is not maintained.
Prevention, protection, decontamination, and infection control are key while treating those suspected to be involved in a biological attack. Primary protection through vaccination is one of the most effective ways of minimizing the impact of a biological agent. Vaccination is possible for anthrax, plague, and smallpox. Postexposure chemoprophylaxis is available for anthrax, plague, Q fever, and tularemia. Decontamination, either mechanical via physical removal of the agent or chemical via destruction of the agent, helps to limit spread of the agent from people or clothing. Dilute bleach solutions are also effective for decontamination—either a 0.5% solution for skin or a 5% solution for equipment. Furthermore, ultraviolet (UV) light or heat can be utilized to effectively kill biological agents on inanimate objects.
The type of infection control precautions that are utilized depend on how the biological agent is transmitted. Universal precautions, consisting of hand washing, gloves, gown, eye protection, and masks, are always recommended when it is likely that body fluids may be encountered. When there is concern about transmission via droplets the patient should also be wearing a mask to limit the transmission of these larger particles. Droplet precautions should be instituted for Bordetella pertussis, influenza virus, adenovirus, rhinovirus, Neisseria meningitidis, and group A Streptococcus. Airborne precautions for particles less than 5 μm in size require special surgical masks/respirators. Agents which require airborne precautions include measles, varicella zoster, Legionella, disseminated herpes zoster, and tuberculosis. When possible, patients should be kept in private rooms or cohorted with others experiencing similar symptoms.
Table 4–1 lists known potential biological agents, likely symptoms, and appropriate medical management.14
Table 4–1Biological agents, signs/symptoms, and treatments. |Favorite Table|Download (.pdf) Table 4–1 Biological agents, signs/symptoms, and treatments.
|Biological Toxin ||Signs/Symptoms ||Medical Management |
|Botulinum ||Cranial nerve palsies, paralysis, respiratory failure ||Antitoxin, supportive care |
|Ricin ||Fever, cough, dyspnea, arthralgias, pulmonary edema ||Supportive care |
|Bacteria ||Signs/Symptoms ||Medical Management |
|Anthrax (Bacillus anthracis) ||Fever, malaise, cough, dyspnea, cyanosis ||Ciprofloxacin |
|Plague (Yersinia pestis) ||High fever, chills, headache, cough, dyspnea, cyanosis ||Streptomycin |
|Brucellosis (Brucella sp.) ||Fever, headache, myalgias, sweats, chills ||Doxycycline |
|Cholera (Vibrio cholerae) ||Massive watery diarrhea ||Fluids; tetracycline, doxycycline, or ciprofloxacin |
|Tularemia (Francisella tularensis) ||Local ulcer, lymphadenopathy, fever, chills, headache, malaise ||Streptomycin |
|Q-fever (Coxiella burnetii) ||Fever, cough, pleuritic chest pain ||Tetracycline |
|Virus ||Signs/Symptoms ||Medical Management |
|Venezuelan equine encephalitis (VEE) ||Fever, encephalitis ||Supportive care |
|Smallpox ||Malaise, fever, rigors, vomiting, headache, pustular vesicles ||Investigational antiviral |
|Viral hemorrhagic fever (VHF) ||Facial flushing, petechiae, bleeding, fever, myalgias, vomiting, diarrhea ||Supportive care |
Toxic chemicals can be used intentionally as weapons, or released unintentionally from industrial accidents. Personal protective gear is required when there is a known threat or attack. Preventing exposure is key. Safe decontamination is paramount when exposure has already occurred. Specific antidotes should be provided as quickly as possible to limit morbidity and mortality. Table 4–2 lists many of the known chemical agents, mechanisms of action, symptoms, and treatments.15,16 Surgical procedures can be safely performed after decontamination, but precautions must still be maintained. Double gloves should be worn, instruments should be cleaned with 5% bleach, and removed objects or tissue should be placed in bleach for disposal. Debridement should be performed with a no-touch technique as much as possible.
Table 4–2Chemical agents: mechanism, signs/symptoms, and treatment. |Favorite Table|Download (.pdf) Table 4–2 Chemical agents: mechanism, signs/symptoms, and treatment.
| ||Mechanism of Action ||Signs/Symptoms ||Treatment |
|Nerve agents |
|Organophosphates (GA, GB, GD, GF, VX) ||Bind acetylcholinesterase ||Miosis, rhinorrhea, dyspnea, loss of consciousness, apnea, seizures, paralysis, copious secretions ||Atropine, pralidoxime chloride |
|Vesicants ||(blister agents) || || |
|Sulfur mustard (HD), nitrogen mustard (HN), Lewisite (L), phosgene oxime (CX) ||Alkylating agent, denatures DNA ||Skin blisters, airway irritation, conjunctivitis, mucus membrane burns ||Decontamination (M291 kit), dimercaprol |
|Inhalation injury ||(choking agents) || || |
|Phosgene (CG) (smells like freshly mown grass/hay) ||Oxidative stress, neutrophil influx ||Throat irritation, pulmonary edema ||N-acetylcysteine, ibuprofen, aminophylline, isoproterenol, colchicine, steroids |
|Chlorine (Cl) ||Inhalation burn ||Small airway and alveolar irritation, dyspnea ||Nebulized steroids, sodium bicarbonate, and beta agonists; mechanical ventilation |
|Diphosgene (DP) ||Airway irritation ||Dyspnea ||Supportive care, mechanical ventilation |
|Chloropicrin (PS) ||Airway irritation ||Dyspnea ||Supportive care, mechanical ventilation |
|Cyanogens ||(blood agents) || || |
|Hydrogen cyanide (AC) Cyanogen chloride (CK) ||Binds to cytochrome oxidase ||Seizures, cardiac arrest, respiratory arrest ||100% oxygen, activated charcoal, sodium nitrite, sodium thiosulfate |
|Hydrogen sulfide (smells like rotten eggs) ||Binds to cytochrome oxidase ||Loss of consciousness, seizures, myocardial ischemia, pulmonary edema, keratoconjunctivitis ||Sodium nitrite |
|Incapacitation agents |
|BZ and indoles: atropine, scopolamine, hyoscyamine ||CNS effects ||Mydriasis, dry mouth, dry skin, increased reflexes, hallucination, impaired memory ||Physostigmine |
|Data from Borden Institute: Emergency War Surgery, 4th edition. Washington, DC: Department of the Army; 2013. |