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

Radiation Syndromes

United States Department of Defense
Peer Review Status: Internally Peer Reviewed

Radiation sickness caused by whole body irradiation may be lethal within a few days to several weeks, depending upon the dose sustained. Clinically, radiation sickness occurs in a dose dependent pattern of three syndromes, determined by the organ system most seriously involved. These are (1) the neurovascular syndrome, caused by very high doses and uniformly fatal within 2-4 days; (2) the gastrointestinal syndrome, due to somewhat lower doses but also uniformly fatal; and (3) the hematopoietic syndrome, caused by still lower doses and associated with the possibility of recovery and survival.

The neurovascular syndrome will be extremely rare in combat. The gastrointestinal syndrome will be relatively uncommon but may be seen. The hematopoietic syndrome will be the most commonly seen.

All three syndromes have certain characteristics in common. These include:

1. An initial nonspecific response
2. A latent period
3. A clinical phase

1. Initial Response. Within a few hours after a prompt exposure, all patients, regardless of which syndrome later develops, pass through a nonspecific, transient period of malaise, weakness, anorexia, vomiting, and diarrhea. This response is probably toxic in nature due to tissue, breakdown products associated with radiation-induced cellular damage. The exact mechanism responsible or the cell mass involved is not known. The initial response to irradiation lasts up to a few hours and then subsides. It is followed by a latent period during which there are no significant symptoms or obvious physical signs of radiation injury. At present, no diagnostic clues are available to establish firmly the presence or extent of radiation injury during the initial response phase. Its severity and duration are not reliable indexes of the degree of radiation exposure and it may be absent following low dose-rate fallout exposures, despite their magnitude.
2. Latent Phase. All three syndromes have latent periods between the initial response and the onset of the clinical phase. This latent period is shortest for the neurovascular syndrome, from an almost negligible period to three days, and longest for the hematopoietic syndrome, lasting 2-6 weeks, with an occasional patient demonstrating an even longer latent period. The gastrointestinal syndrome has an intermediate latent period of a few days. This phase is characterized by a feeling of relative well being.
3. Clinical Phase. The clinical phase follows the latent period and many patients will not be hospitalized until this time, unless they have had other injuries for which they require treatment. As noted previously, there are three distinct syndromes (Figure 20), depending upon the dose of radiation sustained, as follows:
   1. Neurovascular Syndrome. The dose of radiation required to cause each type of clinical response varies considerably. The neurovascular syndrome requires very high doses (3,000 cGy or more). Such doses are rare in a battlefield situation, except for unprotected personnel exposed to extremely intense fallout very close to the point of surface detonation of a large weapon or in an armored vehicle near the detonation of a small device. Therefore, these patients will be rare and in most cases will usually not survive to be seen in medical facilities because of other lethal injuries.

      The clinical course of the neurovascular syndrome is one of progressive depression leading to coma and finally death. In its early stage, patients will be ataxic; convulsions are frequent as the clinical condition deteriorates. This syndrome progresses too rapidly for significant hematologic changes to occur; therefore, diagnosis will not be easy, particularly if patients have sustained head injuries.

   2. Gastrointestinal syndrome. The gastrointestinal syndrome is caused by doses in the range of about 1,000 cGy and higher. These doses will not be common, but exposure to prompt radiation from small weapons or to intense levels of fallout will result in a small number of such patients. Small numbers of patients with this type of radiation sickness were seen among the victims at Hiroshima and Nagasaki.

      A typical patient with this syndrome will have to be hospitalized for other injuries and will, within four to 4-5 days of injury, develop severe, bloody diarrhea. A peripheral blood count will show a depression of lymphocytes and beginning depressions of other leukocytes and platelets. Differentiating between this syndrome and an infectious, nonradiation-induced diarrhea, superimposed upon radiation-induced bone marrow depression, could well be difficult because of the widespread occurrence of various dysenteries in combat. As the bone marrow depression becomes more severe, a point will be reached from which recovery will be impossible. Such patients eventually will succumb to the effects of overwhelming infection and hemorrhage, despite antibiotic therapy and massive fluid, electrolyte, and blood replacement. If patients with gastrointestinal damage are not treated, they will die early due to their massive fluid and blood losses. Replacement therapy can prevent this type of death, but then such patients will progress to the clinical phase of irreparable bone marrow injury. The survival time of such patients will vary, but may be a few weeks. They could constitute a severe burden on all echelons of medical care.

   3. Hematopoietic syndrome. Patients with exposures below levels causing the gastrointestinal syndrome will have longer latent periods before the clinical picture of bone marrow depression becomes evident. This may take from less than two weeks to more than six weeks to develop, but, in most cases, the latent period will be from 2-3 weeks.

      The degree of bone marrow depression will vary with the dose of radiation sustained, and the probability of survival is directly related to the probability of recovery of the bone marrow.

      The clinical picture presented by patients with bone marrow depression will vary, depending upon the presence and nature of other injuries. In uncomplicated radiation sickness, the clinical picture will reflect the increased bleeding tendencies which develop. These patients will develop extensive hemorrhages throughout their bodies. Subcutaneous petechiae and ecchymoses and extensive gastrointestinal bleeding will be common. Decreased resistance to infection will accompany the hemorrhagic diathesis, and infection will be the primary cause of death. Treatment will be limited to supportive measures, such as fluids and antibiotics. Bone marrow transplantation is obviously not practical therapy in the field. Transfusion of blood or blood components will become impractical if the number of casualties is too high. This syndrome is associated with a chance for survival, depending upon the ability of the bone marrow to recover. Bone marrow recovery and an associated favorable prognosis can be determined by serial peripheral blood counts.

 
Figure 20

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