Combined injury: radiation, trauma and burns

A 41-year-old worker arrives at the emergency department of a regional hospital 2 hours after an explosion in an industrial shed where there was a radioactive source used for industrial radiography. He has second and third degree burns on the forearm, face and anterior chest, an open wound on the thigh with a metal fragment and abdominal pain. He vomited once in the ambulance. Blood pressure is 98 over 60 mmHg, heart rate is 118 beats per minute and saturation is 94 percent on room air. The firefighters report that the detector showed contamination on his clothes. The scene is fictional and was written for teaching.

This text uses the scenario as a setting for clinical reasoning for students and health professionals. The topic is combined radiation injury, that is, trauma, burns or both plus radiation exposure. The focus is the order of priorities in the first hours and surgery in the first days. The text does not repeat the lymphocyte triage of acute radiation syndrome, covered in the post on acute radiation syndrome and lymphocyte triage, nor does it discuss radiation in space. If you play the case of the day in NEXO, you will recognize the challenge: the detector draws attention, but what kills in the first hour is the trauma.

Key points

• The order of priority is team safety, then life-threatening injuries, and only then contamination and exposure.
• Radiological decontamination is not an emergency and must never delay life-saving care.
• A burn seen in the first hours is almost always thermal; radiation skin injury takes days to weeks.
• Combined injury worsens the prognosis: in animal models, a non-lethal burn or wound lowers the lethal radiation dose.
• There may be a 24 to 36 hour window to operate before cytopenias appear.

Why this is a reasoning scenario

In a radiation event, the team tends to look at the detector first. The REMM page, the US government's radiation emergency management portal, notes that the most likely cause of death in the first hour is an unrecognized or ignored traumatic injury, and that the novelty of the burn cannot distract the team from the basic principles of trauma (REMM, burns in a radiation emergency). The post on diagnostic pause helps keep the most eye-catching clue from deciding the course of action.

The worker has several clues competing for attention: extensive burns, a metal fragment in the thigh, abdominal pain, one episode of vomiting and contaminated clothes. Each one calls for a different decision. Abdominal pain after an explosion may be a viscus injury from the blast wave, and the vomiting may be from pain, trauma or radiation. The post on differential diagnosis helps keep these hypotheses open at the same time.

What the scene teaches

The scene trains six habits. The first is to follow the order of priorities without skipping steps. The second is to treat the trauma before thinking about the dose. The third is to separate thermal burn from radiation skin injury. The fourth is to decontaminate without delaying care. The fifth is to plan surgery before the blood cells drop. The sixth is to remember that the patient with combined injury is more prone to infection and heals worse.

What is not at stake

The text does not discuss cytokine doses, bone marrow transplant, internal decontamination with drugs or long-term follow-up, topics of other texts in the series. The post on diagnostic uncertainty helps when the dose received is still unknown and a course of action must be taken anyway.

What combined injury is

The definition

The REMM defines combined injury as physical, thermal or chemical trauma plus radiation exposure at a dose sufficient to reduce the chance of survival or functional recovery (REMM, combined injury). It adds three ideas: combined injury will be common in a radiological event with many victims, it has a worse prognosis than trauma or radiation alone, and treatment follows an order of priorities (REMM, combined injury). A review of radiation skin and local injuries recalls that, beyond thermal burns and trauma, these events can cause radiation injuries to the skin, deep tissues and organs, and that combined injury often involves debris wounds, chemical or thermal burns (Iddins et al., 2022).

How many victims would have combined injury

A review of nuclear detonation reports that up to 70 percent of the victims of Hiroshima and Nagasaki had combined injury, but notes that both explosions were air bursts, which produce more burns than a ground-level detonation, the scenario used in current planning (DiCarlo et al., 2011). A lower proportion of combined injury is therefore expected today, especially in the fallout zone, where many people would have radiation exposure only (DiCarlo et al., 2011). The review of the NIAID research program estimates, from historical data, that up to 40 percent of survivors would have radiation and burns, and another 20 percent would also have lacerations or other wounds (DiCarlo et al., 2010).

An experimental study cites the prediction that 65 to 70 percent of the victims of a realistic nuclear emergency would have some traumatic injury in addition to radiation, against 15 to 20 percent with radiation only (Palmer et al., 2013). Another experimental study speaks of about 60 percent (Wang et al., 2024). The numbers vary with the type of event, but the message is the same: in a large event, the typical victim does not have radiation only.

Why the prognosis worsens

Based on several animal models and on human observations, radiation plus trauma or burns greatly increases mortality compared with the same dose of radiation alone (DiCarlo et al., 2011). The table summarizes the data from animal models cited in the reviews.

Model	Finding	Source
Mouse, radiation alone	Lethal dose for half the animals at 30 days of about 963 cGy	(DiCarlo et al., 2010)
Mouse, radiation with a burn of 15 percent of body surface	Lethal dose falls to 820 cGy	(DiCarlo et al., 2010)
Mouse, radiation with a puncture wound	Lethal dose falls to 761 cGy	(DiCarlo et al., 2010)
Dog, burn of 20 percent of body surface	Minimal mortality, of up to 2 percent, which rises to 73 percent with 1 Gy of whole-body irradiation	(DiCarlo et al., 2010)
Rat, burn	Lethality of 50 percent alone and of 65 percent with 1 Gy	(DiCarlo et al., 2011)

The data come from animals and do not transfer directly to humans. The review of nuclear detonation notes, however, that the outcomes of Chernobyl patients with combined injury were poor in all of them (DiCarlo et al., 2011). The post on clinical decision-making helps weigh animal evidence when there is no study in humans.

The mechanism

The extra mortality seems to come, at least in part, from infection by intestinal bacteria: a sublethal wound or burn increases the passage of bacteria from the intestine into the blood caused by irradiation (DiCarlo et al., 2011). Wound closure is also delayed by radiation, in a dose-dependent way, which increases the risk of infection from the skin (DiCarlo et al., 2011). In a mouse model, whole-body radiation plus a skin wound delayed closure and increased mortality compared with radiation alone, by raising susceptibility to infections (Wang et al., 2024). Radiation damages endothelial cells and reduces nitric oxide, which constricts the vessels and reduces flow to the irradiated tissue (Wang et al., 2024).

First the trauma, then the radiation

The order of priorities

REMM lists the priorities in the following order: ensure the safety of those providing care, assess and treat life-threatening injuries and, then, address radiation issues, including external and internal contamination and exposure (REMM, combined injury). The team must use personal protective equipment, and those treating only contaminated patients usually receive minimal exposure, with the exception of patients with radioactive fragments (REMM, combined injury). The radiation protection team must limit working time in heavily contaminated environments (REMM, combined injury).

A review on the management of victims of radiological events sums up the rule in one sentence: decontamination from chemical agents is usually an emergency, radiological decontamination is not (Dent, 2023). Decontamination must never delay life-saving care, and the patient goes through the decontamination corridor once stable (Dent, 2023). In the worker, hypotension and tachycardia come before the detector.

The primary survey

On scene, the team performs the primary survey in protective clothing, removes the worker's clothes, which already removes much of the external contamination, and protects the airway. Facial burns call for attention to the airway. Ultrasound in the emergency room shows free fluid in the abdomen. The post on clinical deterioration helps recognize early the patient who is worsening.

REMM recommends starting volume replacement in major burns with a rough estimate of the burned surface area and adjusting after the formal calculation in the secondary survey (REMM, burns in a radiological emergency). The rule of nines assigns 9 percent to the head and neck, 18 percent to the anterior trunk, 18 percent to the posterior trunk, 9 percent to each arm and 18 percent to each leg (REMM, burns in a radiological emergency). For adults with flame burns, the page indicates 2 mL of lactated Ringer's per kilogram per percent of burned surface area as the adjusted rate, to be titrated by urine output and clinical response (REMM, burns in a radiological emergency). It also warns that hypothermia greatly complicates burn shock and is easier to prevent than to reverse (REMM, burns in a radiological emergency).

The explosion causes several types of injury

A study on victims of major explosions sums up the five types of injury: primary, from the blast wave; secondary, from fragments and debris; tertiary, when the person is thrown or crushed; quaternary, such as worsening of prior diseases and psychological trauma; and quinary, from bacteria, chemicals or radiation associated with the explosion (Wu et al., 2025). Primary injuries are hard to recognize in initial triage, because they are hidden and symptoms may appear late (Wu et al., 2025). In that study, the most severely injured victims underwent resuscitation and damage control surgery (Wu et al., 2025).

In the worker, the thigh wound is a secondary injury, the abdominal pain may be primary or tertiary and the contamination is the quinary injury. The post on signs, symptoms and history helps reconstruct the trauma mechanism from the firefighters' account.

Triage with scarce resources

REMM notes that the available trauma resources depend on the state of the infrastructure and the number of victims, and that mass triage algorithms such as START, for adults, and JumpSTART, for children, improve efficiency (REMM, combined injury). Triage tags designed for radiological events record the dose, the type of exposure, the contamination and the decontamination performed, in addition to the usual data (REMM, combined injury). The page also includes a table of federal planning that shows how the triage category changes with whole-body dose, with and without combined injury (REMM, combined injury).

The review on nuclear detonation recalls another pitfall: patients with burns or trauma can have lymphopenia even without radiation exposure (DiCarlo et al., 2011). That is why the lymphocyte count, so useful in isolated radiation, must be read with caution in the patient with combined injury. The 2018 review by Dainiak recalls that a large event will require protecting professionals from contamination and applying unfamiliar triage and treatment protocols for victims with radiation, trauma and burns (Dainiak, 2018).

Thermal burn or radiation injury

Time separates the two

The review on managing victims of radiological events states that any burn seen soon after the event is almost always thermal, including flash burns (Dent, 2023). Cutaneous radiation syndrome can range from transient erythema and itching to a full-thickness injury, but it takes days to weeks to appear, depending on the absorbed dose and the type of radiation (Dent, 2023). The review on radiation skin injuries adds that these injuries evolve over a longer time than thermal burns, with periods of latency interspersed with active inflammation (Iddins et al., 2022).

In the worker, the burns on the face and chest, already present on arrival, are thermal. That does not rule out a radiation skin injury that will only appear later, especially on the hand and forearm, if he handled the source.

In the same review, the author recalls that burns caused about half the deaths in Hiroshima and Nagasaki and that thermal burn is the main cause of burns in a detonation, because heat reaches much greater distances than radiation (Dent, 2023). Flash burns are limited to exposed skin facing the explosion (Dent, 2023).

Irradiated skin responds differently

The review on skin injuries recalls that, in combined injury, injured and irradiated skin responds in a way not seen in isolated injuries (Iddins et al., 2022). With less blood flow, fewer defense cells reach the site, which impairs healing and increases susceptibility to wound infection (Iddins et al., 2022). For cutaneous syndrome, the consensus cited by Dainiak recommended topical corticosteroid, antihistamine and antibiotic for ulcers, blisters and radiation burns, and surgical excision with grafting for ulcers and localized necrosis with intractable pain (Dainiak, 2018). The post on interprofessional clinical reasoning recalls that the decision about the skin involves surgery, burns, hematology and medical physics.

The surgical window

Operating before the cells drop

REMM states that there may be a 24 to 36 hour window in which surgery can be performed before the onset of cytopenias of acute radiation syndrome (REMM, combined injury). The use of cytokines that stimulate white blood cells can change this window, and the patient needs strict blood count monitoring before and after surgery (REMM, combined injury). The review on managing victims explains why: over days to weeks, the patient may have neutropenia, thrombocytopenia and fluid and electrolyte disturbances, which complicate the procedure and healing (Dent, 2023). If acute radiation syndrome is suspected, surgical interventions work best when performed early (Dent, 2023).

The review from the NIAID program lists the decision on surgical timing among the challenges specific to combined injury, alongside the multiple injuries to treat and the higher risk of sepsis (DiCarlo et al., 2010). At the scene, this means performing the laparotomy and thigh debridement in the first hours, instead of waiting for the estimated dose.

Damage control surgery and definitive surgery

The worker's emergency surgery follows the logic of damage control: stop the bleeding and control contamination of the cavity. What changes with radiation is the plan for the following days. Closing the wound, fixing fractures and performing reconstructive surgeries becomes harder after the cells drop. The post on simulation of care helps train this sequence as a team.

In major burns, REMM describes early excision and reconstruction as the main drivers of recovery, but notes that they are specialized procedures and should be done at a tertiary center whenever possible (REMM, burns in radiological emergency). The window for early excision is flexible, and if transfer to a burn center can be done within a few days, excision should wait for the transfer (REMM, burns in radiological emergency). The page adds that decisions should be made with an experienced burn surgeon, in person or remotely (REMM, burns in radiological emergency).

Infection, wound and blood

The contaminated wound

The review on victim management recommends examining wounds and burns with the detector, to rule out contamination or embedded radioactive fragments (Dent, 2023). Closing a wound with gross radioactive contamination greatly complicates recovery (Dent, 2023). Contaminated wounds should be irrigated with warm water, and the irrigation fluid should be collected and identified as contaminated (Dent, 2023). The patient is considered decontaminated when readings fall below twice the background radiation, which is usually achieved with two decontamination cycles (Dent, 2023).

REMM notes that open wounds require special decontamination procedures and that removal of radioactive fragments must be careful (REMM, combined injury). At the scene, the fragment in the thigh is removed with long forceps, stored in a shielded container and handed to the radiation protection team. Severe wounds may require local excision, graft closure or amputation (Dent, 2023).

Infection

REMM points out that major burn patients become increasingly vulnerable to infection until healing, and that early signs of sepsis are hard to separate from the response to the burn (REMM, burns in radiological emergency). On the page about acute radiation syndrome, REMM recommends considering antimicrobial coverage for skin flora when there are burns (REMM, management of acute radiation syndrome). The review on nuclear detonation reports that antibiotics improved mouse survival after combined injury (DiCarlo et al., 2011).

Blood and marrow

REMM recommends leukoreduced and irradiated blood to treat blood loss in any patient with a dose above 2 Gy (REMM, combined injury). The page also says that dose thresholds for starting growth factors may be lower in the patient with combined injury, and that the decision depends on the size of the event, the number of victims, the nature of the injuries and the available resources (REMM, combined injury). The global consensus on the hematopoietic syndrome notes that transplant outcomes were poor in patients who also had radiation burns, gastrointestinal syndrome, infection, respiratory distress syndrome or renal failure, and therefore recommended against stem cell therapy in patients with aplasia and major injury to another organ (Dainiak et al., 2011).

There is no approved specific treatment

A 2024 experimental study notes that there is no FDA-approved treatment specifically for combined injury (Wang et al., 2024). A 2021 study in mice tested the combination of pegylated granulocyte colony-stimulating factor with L-citrulline in a model of radiation skin wound, after showing that 30-day survival was lower in combined injury than in radiation alone (Wang et al., 2021). These are animal studies, and none of them shows a cure in humans. Supportive care, surgery at the right time and infection control remain the foundation.

The outcome of the scene

The worker goes to the operating room 3 hours after arrival, with the team protected. The laparotomy shows a splenic injury, treated with splenectomy, and the thigh wound is debrided and irrigated. The blood count is repeated every 12 hours. The dose estimate comes later, with the radiation protection team and the reference center, and the interpretation of the lymphopenia takes the burn and the trauma into account.

How NEXO helps train this reasoning

In NEXO, the case of the day is fictional, with a real clinical presentation and up to six progressive clues, and you propose the diagnosis by looking for the ICD-10 code. The combined injury is a good exercise because it forces you to order priorities when several clues compete for attention. The post on learning based on clinical cases explains why this format fixes knowledge.

Three exercises with cases

Change the detector. Say what changes if the detector shows a fragment with a very high reading in the thigh wound.

Change the time. Say how you would plan the surgery if the worker arrived 4 days after the explosion, with falling neutrophils.

Change the skin. Say what you would think if erythema appeared on the right hand 12 days later, with no new heat exposure.

The post on lymphocyte triage helps review the dose estimate once the trauma is under control.

The limits of the game's use are described on the NEXO economy page. If you research the teaching of clinical reasoning, the page for researchers explains how to get in touch. Professionals who write or review cases find information in curation and in creators, and institutions can learn about the proposal on the partnerships page.

Frequently asked questions

Should I decontaminate before treating shock?

No. Radiological decontamination is not an emergency and must never delay life-saving care (Dent, 2023).

Is the burn on arrival caused by radiation?

Almost always not. The burn seen right after the event is thermal; radiation injury appears in days to weeks (Dent, 2023).

When should the patient with combined injury be operated on?

As soon as possible. There may be a window of 24 to 36 hours before the cytopenias (REMM, combined injury).

Does lymphopenia confirm radiation?

Not in trauma or burns, which can cause lymphopenia without radiation (DiCarlo and colleagues, 2011).

Is there a specific treatment for combined injury?

There is no treatment specifically approved by the FDA for it; studies of new therapies are still in animals (Wang and colleagues, 2024).

Final checklist

• I ensured the team's safety with personal protection.
• I treated the life-threatening injuries first.
• I removed the clothing and protected the airway.
• I decontaminated without delaying life-saving care.
• I examined wounds with a detector and removed fragments carefully.
• I separated thermal burn from radiation injury by timing.
• I planned the surgery before the cells dropped.
• I requested leukoreduced and irradiated blood if the dose may exceed 2 Gy.
• I read the lymphopenia taking the trauma and the burn into account.

Want to practice reasoning with progressive clues? Play the case of the day.

References

1. Dainiak N, Gent RN, Carr Z, et al. First global consensus for evidence-based management of the hematopoietic syndrome resulting from exposure to ionizing radiation. Disaster Med Public Health Prep. 2011. PMID 21987000.
2. Dainiak N. Medical management of acute radiation syndrome and associated infections in a high-casualty incident. J Radiat Res. 2018. PMID 29509947.
3. Dent RA. Management of Casualties from Radiation Events. Eur Burn J. 2023. PMID 39600027.
4. DiCarlo AL, Maher C, Hick JL, et al. Radiation injury after a nuclear detonation: medical consequences and the need for scarce resources allocation. Disaster Med Public Health Prep. 2011. PMID 21402810.
5. DiCarlo AL, Ramakrishnan N, Hatchett RJ. Radiation combined injury: overview of NIAID research. Health Phys. 2010. PMID 20445395.
6. Iddins CJ, DiCarlo AL, Ervin MD, et al. Cutaneous and local radiation injuries. J Radiol Prot. 2022. PMID 34488201.
7. Palmer JL, Deburghgraeve CR, Bird MD, et al. Combined radiation and burn injury results in exaggerated early pulmonary inflammation. Radiat Res. 2013. PMID 23899376.
8. Radiation Emergency Medical Management. Burn Triage and Treatment of Thermal Injuries in a Radiation Emergency. Accessed on 24/10/2026. Official source.
9. Radiation Emergency Medical Management. Managing Acute Radiation Syndrome (ARS). Accessed on 24/10/2026. Official source.
10. Radiation Emergency Medical Management. Radiation + Trauma (Combined Injury). Accessed on 24/10/2026. Official source.
11. Wang L, Lin B, Zhai M, et al. Endothelial Dysfunction and Impaired Wound Healing Following Radiation Combined Skin Wound Injury. Int J Mol Sci. 2024. PMID 39684207.
12. Wang L, Zhai M, Lin B, et al. PEG-G-CSF and L-Citrulline Combination Therapy for Mitigating Skin Wound Combined Radiation Injury in a Mouse Model. Radiat Res. 2021. PMID 33914884.
13. Wu Z, Liu J, Xie K, et al. Early medical care and trauma management in mass casualties from major explosive accidents: a retrospective analysis and recommendations. Front Public Health. 2025. PMID 40994753.