Radiation Syndrome

Etiology

Acute radiation syndrome can result from direct exposure or contamination by radioactive materials. Direct exposure can be caused by a nuclear blast, while contamination can result from the ingestion of nuclear-contaminated food, water, and skin contact with the nuclear material. Acute radiation syndrome is divided into 3 groups: hematopoietic, gastrointestinal, and cardiac/neurological systems. Each system will require a different dose of radiation to manifest the symptoms of acute radiation syndrome. The timing of symptoms is also subdivided into prodrome, latent, and manifest phases. The dose, symptom onset, and acute radiation syndrome subdivision are below.[4][5][6][7]

Epidemiology

Radiological or nuclear emergencies are rare but can involve significant numbers of people. After the Chornobyl nuclear power plant disaster in 1986, nearly 6000 children developed thyroid cancer. Radioactive iodine that was either inhaled or consumed from local contamination caused this cancer. Immediately after an accident, local health facilities will be overwhelmed with people wanting to be screened and treated. Areas with local nuclear power plants need to plan accordingly. Major cities now have to worry about the possibility of a dirty bomb.[8][9][10]

Pathophysiology

Radiation is detrimental to body tissues based on how quickly their cells turn over. Those with a high mitotic index will be more severely affected at a lower dose. These include bone marrow, the gastrointestinal tract, and skin.

Toxicokinetics

There are types of ionizing radiation; we will discuss alpha, beta, and gamma. Alpha particles are made up of 2 protons and 2 neutrons. It is easily blocked by clothing but can be inhaled or ingested. Once on the surface of alveoli or intestinal mucosa, it can cause cellular damage, resulting in certain cancers. An example of an alpha particle nuclear material is radon gas. Beta particles are made up of electrons. They have a higher penetrance than alpha particles and can cause damage to the skin. It can also be inhaled as well as ingested. It is the by-product of nuclear power plants and medical nuclear materials like xenon. Gamma rays have no mass and are highly penetrant. They are usually the result of a nuclear detonation.

History and Physical

The initial care of a patient with acute radiation syndrome is based on getting the best history possible. The location, dose, and injuries sustained will make the triage of the patient easier. Record if and when a patient had any vomiting or nausea after the exposure. Vomiting is one of the earliest signs of radiation exposure. A complete physical exam must be performed. At this time, it would be a good idea to take mouth and nostril swabs to be sent for radiation testing. Make notes of any burns or blast injuries. The patient should be surveyed for radiation as per your regional protocol. All surgical or trauma injuries must be triaged appropriately.

Evaluation

All patients with nuclear or radiation exposure should have a baseline complete blood cell count (CBC) with a differential, blood type and screen, and electrolytes. A CBC should be repeated every 6 to 12 hours so as to be able to monitor the white cell count depletion if any. Lymphocyte depletion kinetics are the best predictor of radiation exposure and clinical outcome. Mucosal surface swabs for radiation should be sent to the appropriate labs. Make every effort to document all baseline labs appropriately, as they can help determine future therapies. All baseline radiation levels should be taken before and after decontamination.

Treatment / Management

The staff must be protected from contamination, and all patients with a history of contamination should be disrobed and bathed. You can decrease exposure by 80% just by removing any contaminated clothing. Those individuals with life-threatening injuries are decontaminated as well as possible, but surgical and trauma emergencies will have priority. Surgery should be done within the first 24 hours as significant changes in the patient's ability to fight infection can result from radiation exposure. Supportive care saves lives when it comes to acute radiation syndrome. Fluid management and early treatment of any signs of infection will be fundamental to a better outcome. Prevention of thyroid cancer must be a priority. All children and pregnant women must be offered potassium iodide to protect the thyroid from the uptake of radioactive iodine. Mothers who are breastfeeding should be encouraged to stop if possible.  The following potassium iodide doses should be used daily while in the area of exposure: adult 130 mg, child 65 mg, and infants 1 month to child 3 years old 32 mg.  This is especially important in the case of nuclear power plant accidents. Anti-emetics will be helpful to control nausea. Pain control for burns and other injuries should be a priority. In moderate exposures, it may be necessary to use cytokines and colony-stimulating factors. Early use of antibiotics should be the rule. The use of bone marrow transplant has been used for large dose exposures but remains controversial. Chelating agents are used in some exposures but should be started only after consultation with a nuclear specialist (see Resources). Keep in mind the psychological trauma that can result from radiation exposure. This trauma is more pronounced in children as they will be displaced from their homes and routines.

Differential Diagnosis

The differential diagnosis for radiation toxicity includes the following:

• Acute gastric dilation 

• Acetaminophen toxicity 

• Adrenal insufficiency 

• Appendicitis

• Aspirin toxicity 

• Central nervous system tumor 

• Digoxin toxicity 

• Elevated intracranial pressure

• Pancreatitis 

• Peritonitis