AcuteTraumaticDiaphragmatic Injury

Wa€el C. Hanna, MD, MBA, Lorenzo E. Ferri, MD, PhD, FRCSC, FACS*

KEYWORDS� Diaphragm � Trauma � Surgery � Laparoscopy � Flail chest

In 1579, the French military surgeon AmbroisePare first described the death of a patient fromcolonic strangulation in a diaphragmatic herniacaused by a remote gunshot wound to the chest.Traumatic diaphragmatic injury still represents animportant consequence of penetrating and bluntthoracoabdominal trauma.

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INCIDENCE

Although traumatic diaphragmatic injury has beenreported in 0.5% to 1.6% of patients hospitalizedfor blunt trauma,1 the precise incidence of thisinjury is likely higher than that reported in thesehistorical series. Diaphragmatic injuries, in theabsence of acute diaphragmatic hernias, are oftenmissed by diagnostic imaging and are notoriouslyunderreported. Shah and colleagues2 report thatup to 8% of all patients undergoing a laparotomyor a thoracotomy for trauma will have an incidentalfinding of diaphragmatic injury.

In a series published in 2008, the authors re-ported on 105 patients with traumatic diaphrag-matic injury out of 24,700 (0.52%) admissions toa level 1 trauma center during a 13-year period.Of those cases, only 44% were associated witha traumatic hernia.3 With penetrating trauma, theresulting diaphragmatic defect is often too smallfor herniation in the acute setting. Consequently,acute hernias are present in only one-third of casesunder these circumstances. However, with time, anunrecognized diaphragmatic defect may enlargeand, coupled with the gradient between the nega-tive intrathoracic pressure and positive intraabdo-minal pressure, result in subsequent herniation ofintraabdominal contents into the chest. A pasthistory of penetrating thoracoabdominal trauma is

Division of Thoracic Surgery, McGill University, The MoAvenue, Montreal, Quebec, H3G 1A4, Canada* Corresponding author.E-mail address: lorenzo.ferri@muhc.mcgill.ca (L.E. Ferri).

Thorac Surg Clin 19 (2009) 485–489doi:10.1016/j.thorsurg.2009.07.0081547-4127/09/$ – see front matter ª 2009 Elsevier Inc. All

not uncommon in patients who present withchronic traumatic hernias4 (see the article in thisissue). On the other hand, with blunt trauma, dia-phragmatic injury is a result of dissipation of signif-icant energy from the abdominopelvic cavity intothe chest. Hence, traumatic diaphragmatic injuriesdue to blunt trauma result in a much larger dia-phragmatic defect than that seen in penetratingtrauma and in a higher rate of herniation.3,5

CHARACTERISTICS

Diaphragmatic injury occurs more commonly inthe left hemidiaphragm. About 75% of all acutediaphragmatic hernias are encountered in the leftchest.6 Although some authors maintain that theleft hemidiaphragm is congenitally weaker at itspoints of embryonic fusion,7 it is more likely thatthe cushioning effect of the liver protects a largeportion of the right hemidiaphragm,8 thus reducingthe risk of injury and herniation in this location.Thus, abdominal organs lying to the left of themidline are the ones most frequently found herni-ating into the chest. The stomach is the organwith the highest rate of involvement in acutehernias (48%), followed by the spleen (26%) andthe small bowel, large bowel, and omentum(13%).3 Although less frequent, right diaphrag-matic injuries resulting in herniation of the liverare seen in cases of significant intraabdominalpressure, such as a crush or deceleration injury,resulting in either complete rupture or avulsion ofthe diaphragm.

By virtue of its location between the chest andabdomen, the diaphragm is rarely injured in isola-tion. Most acute traumatic diaphragmatic injuriesare accompanied by injuries to other organs, with

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Fig.1. Penetrating injury to the left lower thorax withobvious herniation of the stomach through the dia-phragm and out of the stab wound.

Fig. 2. Chest radiograph depicting typical findings ofan acute traumatic diaphragmatic injury with a herniacontaining stomach in a patient after a motor vehicleaccident. Note the left hemothorax, multiple rib frac-tures, an air-fluid level, and a curled nasogastric tubein the left chest.

Hanna & Ferri486

some investigators reporting an incidence of asso-ciated injuries as high as 100% and an averageInjury Severity Score of 36.9 The high energy asso-ciated with blunt traumatic diaphragmatic injuryresults in pelvic and long bone fractures in approx-imately 60% of cases.10 Traumatic brain injury ispresent in half of the cases of blunt diaphragmaticinjury and is the only reliable predictor of mortalityin such patients.3

The pattern of associated injuries in penetratingdiaphragmatic hernias is predictably different fromthat in blunt traumatic diaphragmatic hernias. Theauthors and other investigators have reported thatmost associated injuries requiring treatment occurin intraabdominal organs, such as the liver, spleen,stomach, or small bowel, irrespective of theexternal site of the penetrating wound.3

DIAGNOSISPhysical Signs and Symptoms

Because the signs and symptoms of acute dia-phragmatic trauma may often be masked bysevere concomitant injuries to other organs,a high index of suspicion is necessary for the clin-ical diagnosis of this condition. The possibility ofa diaphragmatic injury should be considered inthe context of rapid deceleration or crush injuries.Conversely, a possible diaphragmatic injury shouldbe considered in patients with minimal symptomsafter penetrating trauma to certain locations.External penetrating wounds in the anterior thora-coabdominal area, particularly on the left, shouldheighten awareness of a possible diaphragmaticinjury. Patients with acute diaphragmatic herniamay complain of shoulder pain, epigastric pain,vomiting, or shortness of breath. On physicalexamination, the physician might note the pres-ence of bowel sounds in the chest or the absenceof breath sounds because of compression ofthe lungs by the hernia. Occasionally, a diagnosisof acute traumatic hernia may be made bypalpating abdominal viscera on placement ofa chest tube and rarely by inspection on examina-tion (Fig. 1).

Chest Radiograph

The chest radiograph is an integral adjunct in theAdvanced Trauma Life Support guidelines for theinitial evaluation of the trauma patient, and is oftenthe first clue to the presence of an acute diaphrag-matic injury. Subtle signs on the radiograph, suchas an obscured diaphragmatic shadow, elevatedhemidiaphragm, irregular diaphragmatic contour,or pleural effusion, can suggest injury to thediaphragm.11 However, all these findings mayalso be encountered with the atelectasis,

pneumothorax, hemothorax, or pulmonary contu-sions frequently seen in trauma patients indepen-dent of diaphragmatic injury. In the presence ofa hernia, a chest radiograph provides the diag-nosis in more than 90% of cases.12 Chest radiog-raphy findings consistent with a diaphragmatichernia include a nasogastric tube coiled in theleft chest (stomach in chest) and a supradiaphrag-matic air-fluid level (bowel or stomach in chest)(Fig. 2). The radiographic findings of a right dia-phragmatic injury with herniation of the liver aremore subtle, frequently presenting as an elevatedhemidiaphragm (Fig. 3A). Increasing atelectasison serial films or an inability to adequately ventilatean intubated patient should also raise the suspi-cion of a traumatic diaphragmatic hernia. In the

Fig. 3. (A, B) Chest radiograph depicting the moresubtle signs of an acute right diaphragmatic hernia ina patient sustaining a crush injury. Note the right flailchest and elevated hemidiaphragm typical of a herni-ated liver (A). This patient required internal fixationof the flail segment before placing mattress suturesaround the reduced ribs to repair the hernia (B).

Acute Traumatic Diaphragmatic Injury 487

absence of an acute hernia, the sensitivity of thechest radiograph to diaphragmatic injury is ratherlimited.3,13 The authors reported that the traumabay chest radiograph as read by the emergencyphysicians detects 23% of diaphragmatic injuries.However, attending radiologists who subse-quently read the same images were twice as likelyto identify injuries to the diaphragm,3 suggestingthat image interpretation skills need to beimproved, taking the above-mentioned signs intoconsideration.

The use of oral contrast can significantlyimprove the sensitivity of the chest radiographfor acute diaphragmatic hernias.14 Although theyremain as important diagnostic modalities forchronic diaphragmatic hernias, contrast studiesare rarely obtained in the acute setting, whereassociated injuries may dictate promptmanagement.

Computed Tomography Scan of the Chest

Computed tomography (CT) scan of the chest hasbecome an essential tool for the evaluation of thehemodynamically stable trauma patient. In theabsence of an acute hernia, CT scans offer littlebenefit compared with conventional plain radio-graphs, as the sensitivity of CT for the diagnosisof isolated diaphragmatic injury is limited.15

However, in the presence of herniation of abdom-inal organs into the thoracic cavity, the sensitivityof oral contrast-enhanced CT scan is close to95%.16 The CT scan is especially helpful if theplain chest radiograph is obscured by the pres-ence of a hemothorax or a lung contusion.14 CTscans offer the luxury of determining which organshave migrated into the chest and may also identifyassociated injuries. Although some investigatorsclaim that a CT scan can help with operative plan-ning,16 the authors find that a transabdominalapproach is almost universally used in the acutesetting, given the high rate of associated intraper-itoneal injuries.

Diagnostic Peritoneal Lavage

The sensitivity and specificity of diagnostic perito-neal lavage (DPL) is determined by the red bloodcell (RBC) count. A DPL criterion of 1000 RBC/mm3

has been used to diagnose diaphragm injuries afterstab wounds to the lower chest, flank, or back. Theappearance of lavage fluid in chest tube drainage isa telltale sign of an injury. However, false-negativeresults have been noted in 14% to 40% of patientswith isolated diaphragmatic injuries in 2 series.12

The authors have found that DPL is not particularlyuseful for this condition, and it is included in thisarticle primarily out of historical interest. Further-more, with the advent of bedside focused assess-ment with sonography for trauma (FAST), DPL hasfallen out of favor and is rarely used, except in thesetting where FAST is not available.

Magnetic Resonance Imaging

The utility of magnetic resonance imaging (MRI) forthe assessment of diaphragmatic pathology is wellrecognized. With MRI, in contrast to CT, the dia-phragm can be visualized as a discrete structureand hence a rupture of the diaphragm in theabsence of a diaphragmatic hernia can often bediagnosed from MRI.17 However, the use of MRIremains restricted by its limited availability, andmore importantly, by its impracticality in the acutesetting. Hence, the routine use of MRI in the eval-uation of acute diaphragmatic injury is notrecommended.

Hanna & Ferri488

Exploratory Laparoscopy and Thoracoscopy

Noninvasive diagnostic modalities have a verylimited sensitivity for diaphragmatic injury in theabsence of an obvious diaphragmatic hernia.Thus, in some hemodynamically stable patientswho do not require operative intervention tomanage associated injuries, there exists a realpossibility of missed diaphragmatic injuries, theconsequences of which are discussed in BrianLouie’s article in this issue. In many centers, theadvent of minimally invasive surgical techniqueshas been used to address this issue. In patientswith a high suspicion of diaphragmatic injury,particularly penetrating trauma to the left upperquadrant or left lower chest, the use of exploratorylaparoscopy or thoracoscopy has been advo-cated.18 Murray and colleagues19 used explor-atory laparoscopy and thoracoscopy andreported an alarming 42% incidence of diaphrag-matic injury in patients with penetrating injury tothe left thoracoabdominal area. In such situations,the authors prefer to perform a diagnostic laparos-copy to assess the integrity of the diaphragm inpatients with penetrating wounds in the left lowerchest/left upper quadrant, unless there is a largeretained hemothorax necessitating thoracoscopicdrainage. Diaphragmatic injuries thus identifiedcan be repaired at the same setting by the mini-mally invasive approach.

TREATMENT

Acute traumatic diaphragmatic injuries are treatedby surgical reduction of the herniated organs, ifpresent, and closure of the diaphragmatic defect.Given the high rate of associated injuries to intra-abdominal organs, it is generally recommendedto approach the diaphragmatic injury througha midline laparotomy.3,12 Although penetratingtrauma to the chest is often associated withpulmonary injury, surgical intervention other thana chest tube is rarely required. For certain casesin which a thoracotomy is required to managelife-threatening associated injuries, such asongoing massive hemothorax or aerodigestivetract injury, the diaphragm should be repairedthrough the chest. Large right diaphragmaticinjuries may be difficult to manage through anabdominal approach because of the bulk of theherniated liver and the avulsion of the diaphrag-matic attachments to the chest wall and thusnecessitate a transthoracic approach. However,in these settings, a simultaneous laparotomy isoften indicated to rule out and address possible in-traabdominal organ injury.

Two principles must be observed when repairingacute traumatic diaphragmatic hernias: completereduction of the herniated organs back into theabdomen and watertight closure of the diaphragmto avoid recurrence. Rarely is the hernia difficult toreduce in the acute setting; however, if this isencountered, the phrenotomy can be partiallyextended to facilitate reduction of a tightly incarcer-ated herniated organ. Care must be taken not toinjure the phrenic nerve in the process. In cases ofconcomitant perforation of abdominal viscera, it isimportant to irrigate the chest to reduce the occur-rence of an empyema, which has been shown to be3 times as prevalent when there is documentedbowel injury.3,20 Small diaphragmatic defects maybe repaired using interrupted nonabsorbablesutures. Larger defects will require interruptedfigure-of-eight or mattress sutures, in either a singlelayer or a double layer configuration. The authorsprefer the use of 0 to 1 nonabsorbable braidedsutures for the ease of knot tying. This approachwill address most penetrating traumatic injuries tothe diaphragm. However, blowout injuries of thediaphragm resulting from high-energy crush ordeceleration mechanisms of trauma frequentlyresult in avulsion of this muscle from its chest wallattachments, making simple suture repair impos-sible, particularly on the right side. In these circum-stances, we recommend a transthoracic repair withhorizontal mattress sutures to secure the dia-phragm around the ribs, recognizing that this mayrequire internal plate and screw fixation of thesebones if a large flail segment is present (Fig. 3B).Although some investigators have advocated theuse of prosthetic mesh to achieve a tension-freerepair of large diaphragmatic defects, the authorsadvise against this approach in the acute setting.The use of prosthetics may be of benefit in therepair of chronic diaphragmatic injury, but it carriesa high rate of infection in the acute setting, espe-cially in the presence of hollow viscus injury in theabdomen.

OUTCOMES

Mortality in patients with acute traumatic dia-phragmatic injury is entirely dependent on associ-ated injuries and rarely on the diaphragmatic injuryitself.3 Reported mortality rates vary between 18%and 40%, depending on whether the mechanismof trauma is blunt or penetrating.2,3,18 The mostreliable predictor of mortality in patients with anacute diaphragmatic injury is the Injury SeverityScore. Other predictors of mortality include hightransfusion requirements, rib fractures, and trau-matic brain injury, all of which carry severesequelae and have been shown to be predictors

Acute Traumatic Diaphragmatic Injury 489

of poor outcome in trauma patients. Long-termfollow-up for recurrence after repair of acute trau-matic diaphragmatic hernias can be a difficulttask. The trauma population tends to be young,mobile, and, especially for those on the receivingend of penetrating trauma, difficult to locate.However, there is a suggestion from our seriesthat the recurrence rate of acute diaphragmatichernia is higher when absorbable sutures areused for diaphragmatic repair.3

SUMMARY

Acute diaphragmatic hernia is a result of diaphrag-matic injury that accompanies severe blunt orpenetrating thoracoabdominal trauma. It isfrequently diagnosed early on the trauma baychest radiograph or CT scan of the chest.However, in the absence of a hernia, it may bedifficult to identify traumatic diaphragmatic injuryon conventional imaging. A midline laparotomy isthe advocated approach for repair of acute dia-phragmatic trauma because it offers the possibilityof diagnosing and repairing frequently associatedintraabdominal injuries. In hemodynamically stablepatients with penetrating left thoracoabdominaltrauma, the incidence of injury to the diaphragmis very high, and thoracoscopy or laparoscopy isrecommended for the diagnosis and repair ofa missed diaphragmatic injury. Repair with nonab-sorbable simple sutures is adequate in mostcases, and the use of mesh should be reservedfor chronic and large defects. Outcomes of acutediaphragmatic hernia repair are largely dictatedby the severity of concomitant injuries, with theInjury Severity Score being the most widely recog-nized predictor of mortality.

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