Continuing Education Activity

Prolonged or significant exposure to ionizing radiation can result in acute radiation syndrome (ARS). The National Council on Radiation Protection and Measurements defines this as "a broad term used to describe a range of signs and symptoms that reflect severe damage to specific organ systems and that can lead to death within hours or up to several months after exposure." The proper care of acute radiation syndrome requires planning at the governmental, local and clinical levels to ensure that exposure to radiation is limited and that individuals with acute radiation syndrome are identified and treated appropriately. This activity reviews the presentation, evaluation, and management of acute radiation syndrome and stresses the role of an interprofessional team approach to care for affected patients.

Objectives:

• Identify sources of ionizing radiation.
• Describe the history and physical exam findings typically seen in patients with radiation syndrome.
• Explain how to manage a patient with acute radiation syndrome.
• Review modalities to improve care coordination among interprofessional team members in order to improve outcomes for patients affected by acute radiation syndrome.

Introduction

Radiation is defined as the transmission or emission of energy through space or objects. Radiation can be further divided between ionizing and non-ionizing. Nuclear materials give off ionizing radiation and are measured in sieverts (Sv). The prolonged or significant exposure to such ionizing radiation can result in acute radiation syndrome (ARS). It is defined by the National Council on Radiation Protection and Measurements as “the acute radiation syndrome is a broad term used to describe a range of signs and symptoms that reflect severe damage to specific organ systems and that can lead to death within hours or up to several months after exposure.” The proper care of acute radiation syndrome requires planning at the governmental, local and medical level to ensure the proper treatment and use of limited resources.[1][2][3]

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 three 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 a prodrome, latent and manifest phases. The dose, symptom onset, and acute radiation syndrome subdivision are tabled below.[4][5][6][7]

Epidemiology

Radiological or nuclear emergencies are rare but can involve significant numbers of people. After the Chernobyl 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 turnover. 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 five types of ionizing radiation; we will discuss alpha, beta, and gamma. Alpha particles are made up of two protons and two 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 a 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 six 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 infant one month to child three 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

• Acute gastric dilation 

• Acetaminophen toxicity 

• Adrenal insufficiency 

• Appendicitis

• Aspirin toxicity 

• CNS tumour 

• Digoxin toxicity 

• Elevated ICP

• Pancreatitis 

• Peritonitis

Pearls and Other Issues

Check your local institutions for radiation exposure protocols. Many hospitals have disaster committees with protocols in place for radiation exposures. If your hospital has a nuclear medicine department, they are an excellent source of information on radiation and the treatment of exposure. Several federal agencies have information on radiation disasters. These include  U.S. Homeland Security and the U.S. Centers for Disease Control and Prevention.

Enhancing Healthcare Team Outcomes

Management of acute radiation syndrome is best done by a team of healthcare professionals. When a patient presents with acute radiation exposure, the first thing is to determine the source and secondly protection of other workers. Most hospitals have protocols on the management of radiation exposure. The nest source of information is the nuclear medicine department. Several federal agencies have information on radiation disasters. These include U.S. Homeland Security and the U.S. Centers for Disease Control and Prevention. The care of people exposed to radiation is supportive.