Diaphragmatic Injury Management in the Emergency Department

Currently, 80-90% of blunt diaphragmatic ruptures result from motor vehicle crashes (MVCs). Falls and other traumatic events rarely are implicated. The mechanism of rupture is related to the pressure gradient between the pleural and peritoneal cavities. Lateral impact from an MVC is 3 times more likely than any other type of impact to cause a rupture, since it can distort the chest wall and shear the ipsilateral diaphragm. Frontal impact from an MVC can cause an increase in intra-abdominal pressure, which results in long radial tears in the posterolateral aspect of the diaphragm, its embryologic weak point.

Review of the historical clinical literature, including the series of Carter et al[8] , reveals that the majority (80-90%) of blunt diaphragmatic ruptures have occurred on the left side. The less common right-sided ruptures were seen to have more severe associated injuries and result in greater hemodynamic instability. They required greater force of impact, possibly because the liver provides protection or because of a weakness in the left diaphragm.[9] An autopsy series, however, revealed that left- and right-sided ruptures occurred almost equally. Most likely, these ruptures do occur equally, but the more severe injuries associated with right-sided ruptures cause more deaths and thus a lower rate of patient survival until diagnosis in the hospital. The relative frequencies of right-sided (20-30%) and bilateral (5-10%) ruptures have increased each decade, probably because improvement in trauma care has increased survival rates of patients with significant injuries.

In MVCs, the direction of impact may determine if an injury occurs and on what side. The likelihood of injury is related directly to the direction of impact and the person's position in the car. Persons involved in an ipsilateral impact are more likely to sustain diaphragmatic injury, commonly on the ipsilateral side. In the United States and Canada, this is seen as left-sided injuries in drivers and right-sided injuries in passengers.

Blunt trauma typically produces large radial tears measuring 5-15 cm, most often at the posterolateral aspect of the diaphragm. In contrast, penetrating trauma can create small linear incisions or holes, which are less than 2 cm in size and may present late, after years of gradual herniation and enlargement.

Penetrating injuries to the chest or abdomen also may injure the diaphragm. This specific injury is seen commonly where penetrating trauma is prevalent. This occurs most often from gunshot wounds but can result from knife wounds. Typically, the wounds are small, although occasionally a shotgun blast or an impalement causes a large defect.[10, 11]

Traumatic diaphragmatic rupture (TDR) is uncommon, with the incidence ranging from 1% to 8% in blunt trauma patients. Left-sided diaphragmatic injuries account for 60-70% of cases. These injuries are most commonly accompanied by injuries to the stomach, colon, and spleen. Right-sided injuries represent 30-40% and require higher energy (ie, high-speed motor vehicle collisions). They generally involve the liver or colon. Bilateral injuries are extremely rare, occurring in approximately 3% of the patients.[12]

Diaphragmatic injuries are often related to thoracic and abdominal organ injuries (aorta, kidney, hollow viscera, liver, lung, spleen, pelvic and rib fractures) and severe complications (deep vein thrombosis, pulmonary embolism, hemopneumothorax, pneumonia, respiratory distress, sepsis), with a mortality of 20% being reported.[12]  

Clinical presentation varies depending on the mechanism of injury (ie, blunt vs penetrating) and the presence of associated injuries. Symptoms of diaphragmatic injuries frequently are masked by associated injuries. The diaphragm is integral to normal ventilation, and injuries can result in significant ventilatory compromise. A history of respiratory difficulty and related pulmonary symptoms may indicate diaphragmatic disruption.

Diaphragmatic tears rarely occur in isolation. These patients often have associated thoracic and/or abdominal injuries or may have concomitant head or extremity trauma. The rates for associated injuries in blunt diaphragmatic rupture are as follows:

• Pelvic fractures in 40%
• Splenic rupture in 25%
• Liver laceration in 25%
• Thoracic aortic tear in 5-10%

Diaphragmatic rupture and thoracic aortic disruption are uniquely associated in blunt trauma. In a retrospective chart review, 1.8% of patients with blunt trauma had a diaphragmatic rupture, 1.1% had a thoracic aortic tear, and 10.1% had both.[13] In the last group, the mechanism was high-speed MVC. This association, although rare, is important to consider. The review authors suggested that when one diagnosis is evident, the clinician should further investigate the possibility of the other associated injury.

The physical examination should focus initially on airway, ventilation, and circulation, with concomitant management of airway, ventilatory, or circulatory compromise. Examination of the neck and chest should include a particular focus on findings of tracheal deviation (ie, mediastinal shift), symmetry of chest expansion, and absence of breath sounds (ie, lung displacement). Since the incidence of associated injuries is high, physical findings typically are dictated by these other injuries.

Early diagnosis

Diagnosis may not be obvious. It is made preoperatively in only 40-50% of left-sided and 0-10% of right-sided blunt diaphragmatic ruptures. In 10-50% of patients, diagnosis is not made in the first 24 hours.

Traumatic diaphragmatic injuries are just one of many injuries that can cause acute respiratory compromise.[14]

Physical examination is limited in its utility in diagnosing this injury, but diaphragmatic injury may be identified by auscultation of bowel sounds in the chest or dullness on percussion of the chest. A penetrating injury to the abdomen with a suggestion of a lung or thoracic injury indicates transgression of the diaphragm, as would a chest injury with any suggestion of abdominal injury.

Delayed diagnosis

If not made in the first 4 hours, the diagnosis may be delayed for months or years. Thus, 10-50% of blunt injuries (and an even greater percentage in penetrating trauma) are diagnosed late. This number is decreasing because of greater awareness and earlier identification.

Although the diagnosis may be missed regardless of mechanism, seemingly innocent penetrating injuries may be long forgotten by the patient and are the most commonly missed diaphragmatic injury.

The 3 clinical phases of diaphragmatic injuries were first described by Grimes[15] :

• The first, or acute, phase begins with the injury.

• If not diagnosed early, the second, or latent, phase occurs. This phase is asymptomatic but may evolve into gradual herniation of abdominal contents. The diagnosis may be made later because of complications of herniation of abdominal contents into the pleural cavity.

• The third, or obstructive phase, is characterized by bowel or visceral herniation, obstruction, incarceration, strangulation, and possible rupture of the stomach and colon. If herniation causes significant lung compression, it can lead to tension pneumothorax. Cardiac tamponade has been described from herniation of abdominal contents into the pericardium. Diaphragmatic paralysis also may occur.

Early deaths usually result from associated injuries rather than the diaphragmatic tear. Mortality ranges from 5 to 30%.

Serious morbidity usually is related to reexpansion pulmonary edema or to the laparotomy.

Paralysis or incoordination of the diaphragm is common, but more than 50% of these conditions resolve.

The late complications of an undiagnosed traumatic hernia include bowel herniation, incarceration, and strangulation; tension hemothorax secondary to massive bowel herniation; pericardial tamponade from herniation into the pericardial sac; and diaphragmatic paralysis that may recover after repair.

Death and significant morbidity rarely are related to delayed diagnosis. However, incarceration of herniated abdominal contents can lead to infarction or rupture with disastrous consequences.

Chest radiography is the single most important diagnostic study and may show elevation of the hemidiaphragm, a bowel pattern in the chest, or a nasogastric (NG) tube passing into the abdomen and then curling up into the chest. Additionally, a hemothorax, while not specific for diaphragmatic injuries, may be the only chest radiographic finding. The chest radiograph does not allow direct visualization of the diaphragmatic injury/defect but, rather, the associated herniation or other injuries. The initial chest radiograph is nondiagnostic in approximately 10-40% of patients. Repeated chest radiograph may be helpful. The chest radiographic findings may be masked if the patient is being positive-pressure ventilated (intubated), because this may reduce any herniation. Therefore, obtaining the chest radiograph before intubation or after extubation may be more helpful.

The liver often protects a right-sided rupture from visceral herniation; thus, these ruptures may appear only as an elevated hemidiaphragm from a partially herniated liver. Left-sided ruptures are more evident when the bowel is herniated into the chest.

Chest radiograph of a blunt left diaphragmatic injury often shows an abnormal or wide mediastinum, even when the aorta is normal. The mediastinum should be investigated because of the association with aortic injury discussed previously.

Ultrasonography is commonly used in trauma cases and may visualize large disruptions or herniation; however, it may miss small tears from penetrating injuries. According to the American College of Radiology (ACR) appropriateness criteria, the role of ultrasonography in trauma is primarily for triage, and a positive focused assessment with sonography in trauma (FAST) and signs of hemodynamic instability may lead to immediate surgical intervention. Its use for detection of pleural fluid and pneumothorax is increasing, but it has not gained acceptance for a comprehensive evaluation of blunt chest trauma because of its lack of sensitivity for pulmonary, aortic, cardiac, and musculoskeletal injury.[16]

New-generation helical CT scanning is helpful but not 100% sensitive because of its poor visualization of the diaphragm. A diagnosis can be made if herniation of abdominal contents is visualized. Multidector CT (MDCT) has shown improvement in identifying penetrating and blunt diaphragmatic injury with the use of thin sections and multiplanar formats.[17, 18, 19]  Features of right-sided diaphragmatic rupture seen on MDCT scan include thickened diaphragm, hump, and band signs from herniation of the liver. Segmental diaphragmatic defect, herniation through a defect, and Collar sign (waistlike constriction of the herniated structure at the site of the diaphragmatic rupture) are more useful features of left-sided diaphragmatic rupture.[20]   In a study of 64-slice MDCT for identifying traumatic diaphragmatic rupture, overall sensitivity was 66.7%, specificity 100%, positive predictive value 100%, and negative predictive value 88.4%. However, only 3 of 9 patients with penetrating injury received a correct diagnosis preoperatively.[21]

MRI may aid in the diagnosis because it can accurately visualize the diaphragm's anatomy. MRI may be used in a patient in stable condition who has an equivocal diagnosis and no need for laparotomy (some penetrating injuries) or for late diagnosis.

Thoracoscopy has been used to better visualize the diaphragm when the diagnosis is unconfirmed and laparotomy is not required.

When considering a delayed diagnosis, chest radiography and contrast studies (via NG or enema)  are often used. MRI typically is an ideal diagnostic test in this instance.

Diagnostic peritoneal lavage

When diagnostic peritoneal lavage (DPL) is used to detect diaphragmatic injury, a false-negative result may occur. An isolated penetrating injury from the chest can cause bleeding into the lesser sac, which may not communicate with the rest of the peritoneal cavity. A DPL in this situation would show no evidence of bleeding.

Drainage of lavage fluid from the chest tube has been reported and is a positive result.

In blunt trauma, the DPL result is often positive because of the associated injuries and not specifically because of the diaphragmatic tear.

In penetrating chest injuries, most centers use 10,000 RBC/mm3, a more sensitive criterion than normally used, to limit the number of false-negative results.

Focus on resuscitating the patient. As in all trauma patients, the ABCs are most important. Ensure a patent airway, assist ventilation if required, and begin fluid resuscitation if necessary.

Place an NG tube when possible, as this will help in diagnosis if the NG tube appears in the chest on chest radiograph. Aspiration of gastric contents also helps to decompress any abdominal herniation and to lessen the abdominoperitoneal gradient that favors herniation into the chest.

Consider placing a chest tube to drain any associated hemothorax or pneumothorax. Perform this with caution to prevent injury to herniated abdominal contents within the pleural cavity.

Most surgeons recommend chest tube placement prior to transfer to another facility. If this is not required immediately in the definitive care institution, it may be delayed and completed in the operating room.

Performing chest radiography before intubation may yield a better result (because it is more likely to show associated herniation). A repeated chest radiograph may also add to the sensitivity of diagnosis.

Surgical repair is necessary, even for small tears, because the defect will not heal spontaneously. The parietoperitoneal pressure gradients favor enlargement of the defect with herniation of abdominal contents.

Surgical management usually employs the transabdominal approach to allow a complete trauma laparotomy to search for other injuries. A thoracotomy may be necessary for repair, especially in right-sided injuries or when significant herniation has occurred. In a few situations of isolated penetrating injury where abdominal injury is thought to be unlikely, the repair can be accomplished by thoracotomy or thoracoscopy.[22, 23]

Guidelines

The Eastern Association for the Surgery of Trauma published the following guidelines for traumatic diaphragmatic injuries[7] :

• In left thoracoabdominal stab wound patients who are stable and do not have peritonitis, laparoscopy is recommended over CT to decrease the incidence of missed diaphragmatic injury.
• In penetrating thoracoabdominal trauma patients who are stable without peritonitis in whom a right diaphragmatic injury is confirmed or suspected, nonoperative over operative management is recommended in weighing the risks of delayed herniation, missed thoracoabdominal organ injury, and surgical morbidity.
• In stable patients with acute diaphragmatic injuries, abdominal rather than thoracic approach is recommended to decrease mortality, delayed herniation, missed thoracoabdominal organ injury, and surgical approach-associated morbidity.

The Eastern Association for the Surgery of Trauma published the following guidelines for traumatic diaphragmatic injuries[7] :

• In left thoracoabdominal stab wound patients who are stable and do not have peritonitis, laparoscopy is recommended over CT to decrease the incidence of missed diaphragmatic injury.
• In penetrating thoracoabdominal trauma patients who are stable without peritonitis in whom a right diaphragmatic injury is confirmed or suspected, nonoperative over operative management is recommended in weighing the risks of delayed herniation, missed thoracoabdominal organ injury, and surgical morbidity.
• In stable patients with acute diaphragmatic injuries, abdominal rather than thoracic approach is recommended to decrease mortality, delayed herniation, missed thoracoabdominal organ injury, and surgical approach-associated morbidity.

The American College of Radiology ACR Appropriateness Criteria for major blunt trauma includes the following key recommendations for initial imaging based on suspected injury and/or hemodynamic stability.[16]

Major blunt trauma-hemodynamically unstable

Radiography trauma series and focused assessment with sonography in trauma (FAST)  scan of the chest, abdomen, and pelvis are usually appropriate. These procedures are complementary, and more than one procedure is ordered as a set or simultaneously, where each procedure provides unique clinical information to effectively manage the patient’s care. 

Major blunt trauma-hemodynamically stable

CT whole body with IV contrast, radiography trauma series, and focused assessment with sonography in trauma (FAST) scan of the chest, abdomen, and pelvis are usually appropriate. These procedures are complementary.

Suspected chest trauma-hemodynamically stable

Chest CT with IV contrast, whole body CT with IV contrast, chest CTA with IV contrast, or radiography trauma series is usually appropriate. These procedures are equivalent alternatives (ie, only one procedure will be ordered to provide the clinical information to effectively manage the patient’s care).