Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter VII: Mass Causalties in Thermonuclear Warfare

Triage

United States Department of Defense

If nuclear weapons casualties are encountered, the basic principles of mass casualty management (triage, evacuation, and the use of standardized care interventions) will have to be followed. Our relative inexperience in with these types of patients will make matters worse. Life-threatening doses of acute total body radiation are so infrequently encountered that management policies must be derived in part from different but analogous clinical situations and from studies in experimental animals.

Conventional injuries should be treated first and initial triage should be based on these injuries, since no immediate life-threatening hazard exists for radiation casualties who can ultimately survive. The patient with multiple injuries should be resuscitated and stabilized. During this process, standard preoperative preparation for surgery will accomplish much radioactive decontamination. More definitive evaluation of the radiation injury can be initiated postoperatively.

Three groups of conventional injury patients will have to be considered:

1. Those with minimal injuries that do not incapacitate them completely and are not a significant threat to life. These casualties could continue as at least partially effective soldiers and would not qualify for immediate or early evacuation.

2. Those with severe multiple injuries who obviously are going to require extensive, time consuming care. These also would be delayed.

3. Finally, those with relatively simple injuries which require immediate surgical treatment. These would get first priority for evacuation.

Further classification of patients will not be required prior to evacuation. The presence or absence of radiation injury, in general, will be ignored in this preliminary sorting, since there are no reliable guidelines to aid in the early diagnosis of extent of radiation injury. Eventually, however, all casualties unable to continue as effective soldiers will have to be evacuated.

As noted, there is a requirement for appropriate holding facilities to which patients who cannot be treated immediately or who require only minimal treatment can be evacuated. These facilities should be set up with limited equipment and staffed with small numbers of medical personnel, and should be part of the expansion plans of all field hospitals regardless of size or location. Holding facilities should be as close to hospitals as possible so as to optimize the availability of appropriate additional care and to allow the transfer of patients as the overall situation and balance between medical resources and patient load change. A great variety of patients, including those not fit for field duty but not requiring full-care-type hospitalization, as well as the very severely injured, should be kept there. These should include patients in the following categories:

1. Minimal burns

2. Mild trauma cases

3. Mild chemical injury cases.

4. Severely injured patients who arc not expected to survive and for whom treatment is not immediately available, but for whom supportive measures may be enough to keep them alive until treatment does become available.

Radiation injury introduces many complications into the patient's course. Hematologic injuries cause anemia, infection, bleeding, and delayed wound healing. Performance decrements due largely to neuromediator release can also impact the patient. At higher doses of radiation, dehydration due to severe fluid and electrolyte losses through the intestinal wall will be encountered.

After conventional injuries have been managed, the physician is faced with the problem of triaging the patients according to the severity of their radiation injuries so that appropriate treatment can begin. This problem is difficult since the response of any given individual may vary greatly, and a nonhomogenous exposure of radiation (especially if bone marrow and gut are spared) may result in a markedly decreased effect. U.S. forces do not carry individual personal dosimeters that measure neutron and photon exposures. Finally, dose rate effects can be very profound, especialIy in a fallout environment. In this situation, tactical dosimeters (two per platoon) may be useful to a commander deciding whether to commit exposed troops to battle, but they are less useful to the health care provider. Other problems will also exist. Casualties will be numerous and resources certainly will be strained. Complicating this will be the occurrence of blast and thermal injuries (in addition to radiation injuries). Improved dosimetry is needed for triage since the goal of military medical personnel should be the appropriate allocation of precious resources to salvage the maximum number of casualties. Improved dosimetry is currentIy unavailable, but its desirability is currently undergoing evaluation by the U.S. Army Academy of Health Sciences.

Based on recent recommendations, the following guidelines apply to medical personnel operating in austere field conditions. The lymphocyte level can be used as a biological dosimeter to confirm the presence of pure radiation injury, but not in combined injuries. If the physician has the resources of a clinical laboratory additional information can be obtained to support the original working diagnosis suggested by the presence of prodromal symptoms. An initial blood sample for concentrations of circulating lymphocytes should be obtained as soon as possible from any patient classified as "radiation injury possible" or "radiation injury probable" After the initial assessment, or at least no later than 24 hours after the event in question, additional comparative blood samples should be taken. The samples may be interpreted as follows:

1. Lymphocyte levels in excess of 1500/mm³: There is minimal likelihood of significant dose that would require treatment.

2. Lymphocyte levels between 500 and 1000/mm³: These indicate treatment for severe radiation injury. These patients should be hospitalized to minimize the complications from hemorrhage and infection that will present within 2-3 weeks postexposure.

3. Lymphocyte levels of less than 500/mm³: These patients have received a radiation dose that may prove fatal. All of these patients need to be hospitalized for the inevitable pancytopenic complications.

4. Lymphocytes not detectable: These patients have received a supralethal radiation dose. Survival is very unlikely. Most have received severe injuries to their gastrointestinal and car diovascular systems and will not survive for more than two weeks.

A useful rule of thumb is: If lymphocytes have decreased by 50% or are less than 1000/mm³, the individual has received a significant radiation exposure. In the event of combined injuries, the diagnostic use of lymphocytes may be unreliable. It should be borne in mind that those with severe burns or multisystem trauma often develop lymphopenia.

It is difficult to establish an early definitive diagnosis. Therefore, it is best to utilize a simple, tentative classification system based on three possible categories of patients as discussed below.

1. Radiation Injury Unlikely. If there are no symptoms associated with radiation injury, patients are judged to be at minimal risk for radiation complications. These patients should be triaged according to the severity of their conventional injuries. If the patients are free of conventional injuries or disease states that require treatment, they should be released and returned to duty.

2. Radiation Injury Probable. Anorexia, nausea, and vomiting are the primary prodromal symptoms associated with radiation injury. Priority for further evaluation will be assigned after all life-threatening injuries have been stabilized. Casualties in this category will not require any medical treatment within the first few days for their radiation injuries. Evidence to support the diagnosis of significant radiation injury in the absence of burns and trauma may be obtained from serial lymphocyte assays taken over the next two days. If the evidence indicates that a significant radiation injury was received, these casualties should be monitored for pancytopenic complications.

3. Radiation Injury Severe. These casualties are judged to have received a potentially fatal radiation dose. Nausea and vomiting will be almost universal for persons in this group. The prodromal phase may also include prompt, explosive bloody diarrhea, significant hypotension, and signs of neurologic injury. These patients should be sorted according to the availability of resources. Patients should receive symptomatic care. Lymphocyte analysis is necessary to support this classification.

Categorization of these patients into one of these three irradiation categories will be facilitated by an appreciation for the characteristic symptoms induced by radiation. These are:

1. Nausea and Vomiting. Nausea and vomiting occur with increasing frequency as the radiation exceeds 100-200 centiGrays (cGy). Their onset may be as late as 6-12 hours postexposure. They usually subside within the first day. The occurrence of vomiting within the first two hours is associated with a severe radiation dose. Vomiting within the first hour, especially if accompanied by explosive diarrhea, is associated with doses that frequently prove fatal. Due to the transient nature of these symptoms, it is possible that the patient will have already passed through, this initial phase of gastrointestinal distress before being seen by a physician. It will be necessary to inquire about these symptoms at the initial examination.

2. Hyperthermia. Casualties who have received a potentially lethal radiation injury show a significant rise in body temperature within the first few hours postexposure. Although our experience is limited, this appears to be a consistent finding The occurrence of fever and chills within the first day postexposure is associated with a severe and life-threatening radiation dose. Hyperthermia may occur in patients who receive lower (200 cGy or more) but still serious radiation doses. Present evidence indicates that hyperthermia is frequently overlooked. Individuals wearing a chemical ensemble will normally be hyperthermic; consequently, this may not be a useful sign.

3. Erythema. A person who receives whole-body radiation in excess of 1000-2000 cGy will experience erythema within the first day postexposure. This is also true for those who receive a comparable dose to a local body region in which case the erythema will be restricted to the affected area. With lower but still potentially fatal doses (200 cGy or more), erythema is less frequently seen.

4. Hypotension. A noticeable and sometimes clinically significant decline in systemic blood pressure has been recorded in victims who received a supralethal whole-body radiation dose. A severe hypotensive episode has been observed in one person who had received several thousand rads. In persons who received several hundred rads, a drop in systemic blood pressure of more than 10% has been noted. Severe hypotension after irradiation is associated with a poor prognosis.

5. Neurologic Dysfunction. Experience indicates that almost all persons who demonstrate obvious signs of CNS injury within the first hour postexposure have received a supralethal dose. Symptoms include mental confusion, convulsions, and coma. Intractable hypotension will probably accompany these symptoms. Despite vascular support, these patients succumb within 48 hours.

Casualties receiving a potentially fatal dose of radiation will most likely experience a pattern of prodromal symptoms that is associated with the radiation exposure itself. Unfortunately, these symptoms are nonspecific and may be seen with other forms of illness or injury, thereby seriously complicating the radiation exposure diagnosis. Therefore, the triage officer must determine if the symptoms occurred within the first day postexposure, evaluate the possibility that they are indeed related to radiation exposure, and then assign the patient to one of the three categories: "Radiation Injury Unlikely," "Radiation Injury Probable," or "Radiation Injury Severe" In the last two categories, the observation of changes in circulating lymphocyte counts may either support or rule out the original working diagnosis. All individuals with multiple injuries should be treated initially as if no significant radiation injury is present. Triage and care of any life. threatening injuries should be rendered without regard to the probability of radiation injury. The medical officer should make a preliminary diagnosis of radiation injury only in those patients for whom radiation is the sole source of the problem. This is based on the appearance of nausea, vomiting, diarrhea, erythema, hyperthermia, hypotension, and neurologic dysfunction.

Decontamination of the Patient. Radiation injury per se does not imply that the patient is a health hazard to the medical staff. Studies indicate that the levels of intrinsic radiation present within the patient from activation (after exposure to neutron and high-energy photon sources) are not life-threatening to the medical staff.

Patients entering a medical treatment facility should be routinely decontaminated if monitoring for radiation is not available. Removal of the patient's clothing will usually reduce most of the contamination. Washing exposed body surfaces will further reduce this problem. Both of these procedures can be performed in the field or on the way to the treatment facility. Once the patient has entered the treatment facility, care should be based on the obvious injuries. Care for life-threatening injuries should not be delayed until the decontamination procedures are completed.

When radiation safety personnel are available, decontamination procedures will be established to assist in rendering care and to minimize the hazard from radioactive contaminants. A more extensive decontamination procedure is to scrub the areas of persistent contamination with a mild detergent or a diluted strong detergent. Caution should be taken to not disrupt the integrity of the skin while scrubbing, because disruption can lead to incorporation of the radioisotopes into deeper layers of the skin. Contaminated wounds should be treated first, since they will rapidly incorporate the contaminant. Washing, gentle scrubbing, or even debridement may be necessary to reduce the level of contaminants.

Wearing surgical attire will reduce the possible contamination of health personnel. If additional precautions are warranted, rotation of the attending personnel will further reduce the possibility of significant contamination or exposure. The prevention of incorporation is of paramount importance. The inhalation or ingestion of radioactive particles is a much more difficult problem, and resources to deal with it will not be available in a field situation.

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Operational Medicine 2001

Health Care in Military Settings

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