Emergency Radiology

, Volume 13, Issue 3, pp 113–122

Blast injuries from Madrid terrorist bombing attacks on March 11, 2004


  • Milagros Martí
    • Department of RadiologyUniversity Hospital La Paz
    • Department of RadiologyUniversity Hospital La Paz
  • Franziska Baudraxler
    • Department of RadiologyUniversity Hospital La Paz
  • Aranzazu Royo
    • Department of RadiologyUniversity Hospital La Paz
  • Nieves Gómez León
    • Department of RadiologyUniversity Hospital La Paz
  • Rodolfo Álvarez-Sala
    • Department of PneumologyUniversity Hospital La Paz
Review Article

DOI: 10.1007/s10140-006-0534-4

Cite this article as:
Martí, M., Parrón, M., Baudraxler, F. et al. Emerg Radiol (2006) 13: 113. doi:10.1007/s10140-006-0534-4


Blast injuries after terrorist attacks are seen with increasing frequency worldwide. Thousands of victims were attended in the hospitals of Madrid, Spain, on March 11, 2004 after the bombing attacks against the commuter trains. Thirty-six patients were attended in our institution. Seventeen of them suffered from severe or life-threatening injuries, and 19 had mild injuries. The most common lesions were thoracic trauma and blast lung injury, acoustic trauma, and orbital and paranasal sinus fractures. Other findings were hepatic and splenic lacerations, and vertebral and limb fractures. Emergency radiology had an important role in the correct management of the victims. Prompt radiological diagnoses of these complex lesions are crucial to efficient treatment. Therefore, radiologists have to become familiar with the injury patterns and specific lesions caused by blast wave.


TerrorismBlast injuriesBlunt injuriesDiagnostic imagingComputed tomographyRadiography


There are various scenarios that lead to injury from blast, sometimes referred to as blast overpressure injury. However, the number and extent of worldwide terrorist attacks has risen sharply in recent years [1, 2].

Terrorism has been defined as all kinds of criminal acts directed against a state and intended or calculated to create a state of terror in the minds of particular persons or a group of persons or the general public [3].

An explosive is any substance or device capable of a sudden expansion of gas, which upon release of its potential energy creates a pressure wave. Compression of air in front of the pressure wave, which heats and accelerates air molecules, leads to a sudden increase in atmospheric pressure (overpressure) and temperature transmitted into the surrounding environment as a radially propagating shock wave known as the “blast wave” [4, 5]. The blast wave consists of two parts: a shock wave of high pressure, followed closely by a blast wind or air in motion [6] (Fig. 1).
Fig. 1

The blast wave moves outward radially from the center of the explosion with very high velocities. As it expands, the peak pressures and energy of the blast wave diminish, and the speed of propagation decreases from the initial supersonic velocity to that of sound in the transmitting medium in inverse proportion to distance from the explosion focus

Injuries provoked by explosive blasts were classified by Zuckerman during the Second World War according to the physical effects on the body caused by the released energy (Table 1) [4, 6]:
  • Primary blast injuries are caused solely by the direct effect of blast overpressure on tissue. Unlike water, air is easily compressible. As a result, primary blast injuries usually affect air-filled organs and air–fluid interfaces such as the lungs, the middle ear, and the gastrointestinal tract. Rupture of tympanic membranes, pulmonary damage, and air embolization, as well as rupture of hollow viscera, are the most important primary forms of blast injury.

  • Secondary blast injuries, like penetrating trauma and fragmentation injuries, are caused by bomb fragments and other displaced objects.

  • Tertiary blast injuries are caused by the effects of structural collapse and of persons being thrown by the blast wind (penetrating or blunt trauma, fractures, and traumatic amputations).

  • Quaternary blast injuries refer to burns, toxic inhalation, exposure to radiation, asphyxiation, and inhalation of dust and include exacerbations or complications of persisting conditions (e.g., patients receiving anticoagulants, pregnant women, etc.).

Table 1

Zuckerman classification



Body part affected

Types of injuries


Caused by the impact of the over-pressurization wave with body surfaces

Air containing structures are most vulnerable (ear, lungs, gastrointestinal tract)

Blast lung, bowel perforation and hemorrhage, mesenteric shear injuries, solid organ lacerations, eye perforation, tympanic membrane rupture, ossicular disruption, cochlear damage, brain contusions without physical signs of head injury


Caused by bomb fragments and other displaced objects

Any body part may be affected

Penetrating ballistic (fragmentation) or blunt injuries


Caused by individuals being thrown by the blast wind

Any body part may be affected

Penetrating or blunt trauma, fractures and traumatic amputations, closed and open brain injury


All explosion-related injuries, illnesses, or diseases not due to primary, secondary, or tertiary mechanisms. Includes exacerbation or complications of existing conditions

Any body part may be affected

Burns, breathing problems from toxic fumes

The effects of blasts consist of primary, secondary, tertiary, and quaternary injuries; this was modified from the Centers for Disease Control and Prevention (http://www.bt.cdc.gov/masstrauma/explosions.asp).

The injuries suffered by survivors of these attacks combine the lethal effects of penetrating trauma, blast injury, and burns [2, 7, 8]. However, bombing incidents are prone to be highly variable concerning scene settings, victim populations, and explosive charge properties including weight and chemical structure [9]. In general, damage decreases exponentially with distance from the point source of the blast [10]. When explosions take place inside buildings, trains, and busses, standing waves and enhanced differences in pressure occur because of the additive effects of reflections or reverberations from walls and rigid objects [6, 9]. Reflection from surfaces such as walls can increase the blast effect by a factor to two to eight [11].

The Madrid train bombing attacks on the morning of March 11, 2004 (also known as 11/3, 3/11, M-11, and 11-M) were a series of coordinated terrorist bombings against the commuter train system of Madrid that killed 191 people and wounded almost 2,000 (Fig. 2). Of the 13 Madrid hospitals, the University Hospital La Paz is located furthest from the bombing places (8.2 km); still, emergency medical services were instructed to evacuate injured victims to all hospitals. La Paz is a level I trauma center in Madrid, with experience in recognizing and treating complex injuries.
Fig. 2

The bombing attacks on March 11, 2004 consisted of a series of ten explosions that occurred at the height of the Madrid rush hour aboard four commuter trains (Cercanías in Spain). Thirteen improvised explosive devices were reported to have been used, three of them detonated. This picture shows one of the trains minutes after the bomb explosion. Note the vast shattering of the train casing

This article provides a description of radiological findings of blast injuries among victims admitted to the University Hospital La Paz on March 11, 2004, emphasizing specific lesions like blast lung injury. It is our intention to review the injury patterns resulting from explosions in a semi-confined space.

Materials and methods

Within the short period of 30 min, 36 patients were brought to the emergency department. Twenty patients were men and 16 were women, including one pregnant woman.

The patients hospitalized had a median age of 37 years (16–56 years; Fig. 3). Patients were classified by means of a color code: “green” for mild injuries, “yellow” for severe injuries, and “red” for life-threatening injuries.
Fig. 3

Number of patients according to their age

Each severely injured patient (yellow and red) was surveyed by a physician team (intensivist, orthopedic, and general surgeon).

On March 11, the radiologic team consisted of one coordinator radiologist, one emergency radiologist, two neuroradiologists, and three radiologists in training.

The means at our disposal at the emergency radiology area were:
  • Plain radiograph (GE; two systems)

  • Portable plain radiograph (GE; two systems)

  • Ultrasonography, Power Vision (Toshiba)

  • Portable ultrasonography (Tosbee)

  • Dual multidetector helical Computed Tomography (CT), Asteion Dual (Toshiba)

In addition, there were other two helical CT systems (Somaton Plus, Siemens) available in the general radiology area.

CT examinations were performed in accordance with our routine departmental protocol. Sequential cranial CT was undergone first. Then, thoracic and abdominal scans were obtained from the apex of the lungs to the inferior edge of ischia after intravenous contrast injection. One hundred and thirty milliliters of contrast material was administered by bolus injection with a scan delay of 50 s. No oral contrast medium was given before the examinations. Approximately, the total scan time was 25 s. In some patients, cervical or facial CT was also performed. Oral and handwritten reports were immediately elaborated.


After the initial evaluation, 19 (57%) patients were classified as green, four (10%) as yellow, and 13 (33%) as red patients (Fig. 4).
Fig. 4

The number of victims injured according to the triage classification

Imaging approach

During the first 3 h after the admittance of the patients in the emergency area, there were 17 cranial CT performed, 16 body CT, 2 cervical spine CT, 4 facial CT, 6 focused abdominal sonogram for trauma (FAST), 3 abdominal sonograms, 24 plain chest radiographs, 16 lower limb radiographs, and 24 radiographs of other anatomic regions.

Distribution of injuries

Green patients

The most frequent injuries were acoustic trauma and minor thoracic lesions (Table 2). Rupture of tympanic membrane was present in 14 of the 19 green patients (63%) and bilateral in two of them (11%). Twelve patients suffered from minor thoracic lesions (63%). None of them showed lung findings on plain chest radiograph. In addition, minor skin lesions were also present, namely in the face and neck (10 patients) and limbs (13 patients).
Table 2

Distribution of injuries in green patients


Number of patients (%)

Acoustic trauma

 Unilateral rupture of tympanic membrane

12/19 (63%)

 Bilateral rupture of tympanic membrane

2/19 (11%)

 Minor thoracic trauma

12/19 (63%)

 Skin injuries

13/19 (68%)

All of the 19 green patients were discharged from the emergency department throughout March 11.

Severely injured (yellow and red) patients

Overall, the chest was the most commonly affected body region (n = 16, 94%), followed by head/neck (n = 13, 77%), blunt abdominal injury (n = 4, 24%), high grade skin burns (n = 4, 24%), and open lower limb fracture (n = 2%; see Tables 3 and 4).
Table 3

Main injured body region in yellow and red patients


Number of patients (%)


16/17 (94%)

Head, face, and neck

13/17 (77%)


4/17 (24%)


4/17 (24%)

Skin (severe burns)

4/17 (24%)

Table 4

Head and neck, thoracic, and abdominal lesions in severely injured patients diagnosed in the first imaging approach



Imaging studies

Head and neck

 Paranasal sinus fracture

9/17 (53%)


 Orbit fracture

8/17 (47%)


 Petrous fracture

3/17 (18%)


 Hemorrhagic brain contusions

3/17 (18%)


 Subarachnoid hemorrhage

1/17 (6%)



1/17 (6%)



 Blast lung injury



 Pleural effusion

7/17 (41%)


 Rib fractures

5/17 (29%)


 Pneumothorax (tension)

3 (1)/17 (18%)


 Vertebral fractures

2/17 (12%)


 Mediastinal hematoma

2/17 (12%)


 Subcutaneous emphysema

2/17 (12%)



2/17 (12%)



 Liver laceration

1/17 (6%)


 Spleen laceration

1/17 (6%)


 Free peritoneal fluida

1/17 (6%)


 Abdominal pain without imaging findings

1/17 (6%)

2 US + CT

CT Computed tomography, US abdominal sonogram.

aThe patient underwent a laparotomy to have the peritoneal cavity explored, but no lesions were found.

Head, neck, and spine

The most frequent head and neck injuries were tympanic membrane perforation, paranasal sinus fractures (n = 9, 53%), and petrous fractures (n = 3, 18%). Maxillary sinuses were the most frequently injured one (Fig. 5). However, these fractures were associated with other injuries (zygomaticomaxillary complex, frontoethmoidal, orbital, and endocranial lesions) in most of the patients (Fig. 6).
Fig. 5

Bilateral floor blowout fracture. Reformatted coronal CT image shows the fracture of each orbital floor. Note the mass of orbital soft tissues herniated through the fracture defect (arrows), including the inferior rectus muscle (asterisk)

Fig. 6

Severely comminuted left zygomaticomaxillary complex. The fracture axial CT image shows the anterolateral and posterolateral antral wall fractures, associated with left zygomatic arch fractures (arrows). The left antrum is completely opacified, presumably by blood (asterisk). Note the soft tissue swelling and subcutaneous emphysema (arrowhead)

The orbital injuries consisted of fractures (n = 8, 47%) and hemovitreous (n = 1, 6%; Fig. 7).
Fig. 7

Hemovitreous. a Axial CT scan through midorbits shows high attenuation material within the right vitreous chamber corresponding to hemorrhages (arrows). There is a high-density blood-vitreous level within the dependent portion of the left globe (asterisk). b Right ocular globe ultrasonography demonstrates biconvex choroidal hemorrhages (arrows) and heterogeneous echogenic foci (hemorrhage) within the vitreous (asterisk)

Blast injuries to the brain included parenchymal contusions (n = 3, 18%) and subarachnoid hemorrhage (n = 1, 6%; Fig. 8).
Fig. 8

Subarachnoid hemorrhage. Axial CT image shows high attenuation subarachnoid hemorrhage in the suprasellar cistern (arrow). Note the presence of pneumocephalus due to a frontal sinus fracture

Body CT revealed two dorsal vertebral body fractures and lumbar transverse apophysis fractures in two patients (one of them developed a psoas hematoma).


There were radiological findings consistent with blast lung injury in 16 patients (94%). Radiological findings of primary blast lung injury were characterized by ground-glass opacities or consolidations. Some of them showed perihilar lung consolidation, which had been previously described in blast-injured patients (Figs. 9, 10, and 11). However, other patients had patchy, subpleural opacities in one or both lungs. It was accompanied by significant barotrauma in these patients (Figs. 12 and 13).
Fig. 9

Serial appearance in a patient with radiographical improvement. Frontal chest radiography (a) and axial (b) CT images performed within the initial 2 h show diffuse confluent air space opacities, predominantly involving central regions of both lungs. Note the presence of posterior mediastinal hematoma (asterisk), but no great vessel injury was detected

Fig. 10

Blast lung injury. Vague, ill-defined, and poorly marginated perihiliar densities in the frontal projection (butterfly wind-like pattern)

Fig. 11

Blast lung injury. Axial CT image (mediastinal window) demonstrates an extensive area of increased attenuation with air bronchogram sign in the center of the consolidation

Fig. 12

Pneumothorax. Axial CT image displays anteromedial and apicolateral left air pleural collection (asterisk), which induces a contralateral shift of the mediastinum, corresponding to a pneumothorax, with a lateral rib fracture (arrow). The posterior lung consolidations (arrowheads) are probably related to lung contusions

Fig. 13

Blunt lung injuries. Axial CT image shows bilateral, peripheral pulmonary areas of increased density, irregularly distributed among both lungs, which is the typical radiological appearance of pulmonary contusion (arrows). The left contusion is due to a rib fracture, probably caused by a direct blow to the thoracic wall. Note the subcutaneous emphysema (arrowheads) and the tracheal tube

CT was found to be more sensitive than plain chest radiography in the detection of subtle pulmonary lesions (Fig. 14).
Fig. 14

CT accurately reflects subtle thoracic lesions. The initial supine anteroposterior chest radiography was interpreted as being normal (not shown). CT image revealed ill-defined perihiliar pulmonary infiltrate surrounded by a ground-glass opacity area. There was a very small, subtle right pneumothorax (arrow) that was not apparent on plain radiography

The spectrum of associated thoracic lesions included pleural effusion (n = 7, 41%), rib fractures (n = 5, 29%), pneumothorax (n = 3, 18%, a tension pneumothorax in one patient, with contralateral deviation of mediastinal structures), mediastinal hematoma (n = 2, 12%), pneumomediastinum (n = 2, 12%), vertebral fracture (n = 2, 12%), and subcutaneous emphysema (n = 2, 12%; Figs. 9b, 12, and 13). No great mediastinal vessel injuries were detected.

Significant changes were detected by serial chest radiographs, showing an increasing density and number of consolidation, especially in two patients who underwent abdominal surgery (Fig. 15).
Fig. 15

Serial appearance in a patient with progressive deterioration. Frontal chest radiography obtained at admission to the hospital (a) demonstrated multifocal, peripheral lung opacities. Note the presence of right pleural effusion. Follow-up frontal chest radiography obtained 7 days later (b) showed a progression of radiographic findings, with multifocal bilateral air space opacities in both lungs. In this patient, respiratory failure might have been induced by the severe skin burns, requiring assisted ventilation


Blunt abdominal trauma was observed in four patients (24%). Two patients suffered solid organ laceration, a hepatic laceration, and a splenic laceration. In another patient, the abdominal ultrasound and CT scan showed intraperitoneal free fluid. He underwent laparotomy to have the peritoneal cavity explored, but no lesions were found. The fourth patient had an important abdominal pain without findings on FAST, abdominal ultrasonogram, and CT. The symptoms improved with conservative treatment.


A 29-year-old woman at 7 months gestation was evacuated to our hospital. She underwent sudden hypotension and shock. The FAST revealed fetal death and massive hemoperitoneum. CT showed a hepatic laceration and hemoperitoneum (Fig. 16). She was taken to the operating room to undergo a laparotomy, but she died.
Fig. 16

Hepatic laceration in a pregnant woman. a Axial CT scan (without intravenous contrast media) demonstrates a poorly defined area of low attenuation in the right lobe (arrows), representing an important hepatic laceration. Note the presence of a massive hemoperitoneum (asterisk). b Pelvic CT image shows the 29-week fetus. A previous ultrasound was performed just before the CT scan and revealed absent fetal heartbeat


Some patients sustained fractures in the extremities, two of them being comminuted, open fractures (Fig. 17). Burns and penetrating soft tissue injuries from fragments and foreign bodies were severe in some of these patients.
Fig. 17

Opened limb fracture. Anteroposterior projection shows comminuted, displaced fracture of the tibial and fibular diaphyses. Multiple foreign bodies (arrowheads) are present in soft tissues


During the last years, Spain has experienced its share of death and injury including the casualties of the terrorist bombing attacks on March 11, 2004 in Madrid. Traumatic injury is a disease of the young, and the patients hospitalized at our center had a median age of 36 years, which is comparable to casualties of previously known trauma types, but higher than in other series [12]. This is due to the fact that most of the victims were workers or students.

In-hospital fatality rates were significantly lower than in other terrorist acts or in the case of war fatalities [12, 13]. The remoteness of our hospital from the explosion scenario may explain this event. The bombing incidents occurred within a train coach that is a confined space. Previous studies have claimed that, compared to patterns of injury in the open air blasts, explosions in confined spaces imply an overall increased mortality, more severe injuries, and higher incidence of primary blast injuries. However, there is no difference regarding the incidence of penetrating trauma or traumatic amputations [8, 9, 14] between the two groups.

The distribution and pattern of injuries are fundamentally comparable to the epidemiology of other series [9, 12, 1518]. Injuries occurred predominantly to the head, neck and limbs, followed by the chest and abdominal organs. The tympanic membrane is the structure most frequently injured by blast [6]. Therefore, rupture of the tympanic membranes observed in otoscopy serves as a sensitive marker for blast injuries in the triage [19].

The lungs are particularly susceptible to damage due to the extensive air/lung tissue interfaces. In addition, blast energy has been associated to tissue hypoxia, antioxidant depletion, and subsequent oxidative damage [11, 2022]. Furthermore, the development of pulmonary dysfunction and sepsis/systemic inflammatory response syndrome remains a major threat to survival [9, 11, 23].

There were radiological findings consistent with blast lung injury in 94% of our severely injured patients. However, primary blast lung injury was associated to injury due to blunt trauma, with rib fractures or chest wall injury. Radiological findings of primary blast lung injury are characterized by ground-glass opacities or consolidations. Perihilar lung consolidations have been previously described in blast-injured patients. Still, patchy, diffuse, and subpleural opacities, might be explained by “rib imprint” hemorrhages across the surface of the pleura. Early characteristic infiltrates on chest radiographs, accompanied by severe barotrauma without rib fractures, strongly support the hypothesis that the main lung injury was caused by the blast wave itself [8]. These radiological findings show the diffuse alveolar over-distension characterized by alveolar ruptures; thinning of alveolar septae; and enlargement of alveolar spaces, subpleural, intra-alveolar, and perivascular interstitial hemorrhage around pulmonary vessels; venous air embolism; and bone marrow and fat embolism observed in the histopathologic specimen [4, 24, 25]. In addition, the delayed effects observed over the next 24 to 48 h bear similarities to acute respiratory distress syndrome [26], which is more evident in patients who underwent a surgical operation.

Most of the head and neck injuries are due to direct blast effect (primary blast injuries) over air-filled cavities (middle ear, paranasal sinuses, and mastoid cells). Maxillary sinuses were the most commonly injured ones. However, these fractures were associated with other injuries (zygomaticomaxillary complex, frontoethmoidal, orbital, and endocranial lesions) in most of patients. Orbital injuries were due to a combination of direct blast effect over the fluid-filled globe (primary blast injuries) and blunt trauma (secondary or tertiary injuries) in which fragments of glass, bomb casing, masonry, or any other unsecured items were propelled by the explosion [27]. Despite the relatively small surface area of the eyes, ocular injuries are not an uncommon cause of morbidity in victims of terrorist blasts [2729]. Brain and spine lesions are mainly due to blunt trauma, although primary blast waves can cause concussions or mild traumatic brain injury without a direct blow to the head.

Blunt abdominal trauma was only observed in four of the victims. Rupture of the hollow viscera did not occur in our patients, although the colon shows to be the most frequent abdominal visceral structure injured in other series [30, 31]. Aside from laceration and hemorrhage of solid organs such as the liver and spleen, mesenteric ischemia or infarct may occur. The primary blast injuries to the abdomen are associated to barotraumas caused by secondary or tertiary mechanism. Quaternary blast injuries include complications of preexisting conditions, e.g., pregnancy. The pregnant woman who fell victim of the terrorist bombing had a hepatic laceration causing a massive hemoperitoneum. Probably the gravid uterus blunted the liver and caused the hemoperitoneum and shock. Transmission blast and stress wave energy is higher in fluid environments. In this case, the fetal death could directly be due to the collision of the blast wave with the fetus surrounded by the amniotic fluid, although the most common cause of fetal death is maternal shock.

Traumatic limb injuries are a consequence of the blast effect and high-energy primary fragment (part of the weapon) and secondary fragment (those that result from the explosion) injuries. Approximately 60% of the patient had orthopedic injuries. These lesions spanned a broad spectrum including soft tissue injuries, fractures, or even comminute fractures. Lower extremity is more frequently involved than the upper extremities. The complex nature of the injuries implies a high risk of infection and the need of additional surgical treatments [15].

In summary, the injuries suffered by the victims of the bombing attacks to the commuter trains on March 11, 2004 in Madrid had been produced by different mechanisms of blast injury simultaneously, and they were multiple and severe. When dealing with blast-injured patients, a precise triage in the emergency room is mandatory for an adequate imaging approach. Based on our experience, the radiologist should be able to recognize the whole spectrum of injuries inflicted by blasts and explosions. Prompt radiological diagnosis of these complex lesions is crucial to the efficient management of the victims.

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© Am Soc Emergency Radiol 2006