Rib Fracture Causing Delayed Aortic Laceration

May 25, 2007
Surgical Rounds®, October 2006, Volume 0, Issue 0

Elizabeth A. Sailhamer, General Surgery Resident, Department of Surgery, Massachusetts General Hospital; George C. Velmahos, Professor and Chief, Division of Trauma, Emergency Surgery, and Surgical Critical Care, Massachusetts General Hospital, Harvard Medical School, Boston, MA

Elizabeth A. Sailhamer, MD General Surgery Resident

Department of Surgery

Massachusetts General Hospital

George C. Velmahos, MD, PhD

Professor and Chief

Division of Trauma, Emergency Surgery, and Surgical Critical Care

Massachusetts General Hospital

Harvard Medical School

Boston, MA

Injury to the thoracic aorta after blunt trauma is rarely caused by rib fractures. The authors report a unique case of such an injury and review the literature, which yielded six similar cases. Most of these patients had delayed presentations. Although expectant management has been used with some success when foreign objects are found abutting large vessels, rib fractures should be considered differently. Based on the few cases reported in the literature, reduction of the displaced rib under controlled circumstances by a team prepared for a rapid thoracotomy offered the best chance for survival.

Thoracic aortic injury is usually a deceleration injury that occurs after blunt trauma. These injuries are typically located at points of aortic fixation, such as the ligamentum arteriosum. The presence of first and second rib fractures is considered an indicator of high-energy transfer and cited as a risk factor for blunt injury to the thoracic aorta. Lower rib fractures may coexist with thoracic aortic injuries but are not considered risk factors when other findings, such as a widened mediastinum, are absent. On rare occasions, the sharp edges of rib fractures have caused aortic lacerations.1-6 In all such cases, a significant mechanism of injury, multiple rib fractures, and associated injuries were present. We report a case of delayed aortic rupture from a posterior rib fracture following a low-level fall. The cumulative literature suggests that a displaced posterior rib fracture adjacent to the aorta requires intervention to prevent aortic injury.

Case report

A 62-year-old woman presented to the emergency department of another hospital reporting moderate left posterior chest wall pain after falling 5 feet from a stepladder while cleaning her windows. The patient was hemodynamically stable. A plain chest radiograph was unremarkable. A computed tomography (CT) scan of her chest identified left-sided fractures of ribs 9 through 12, with the posterior spiked edge of the 10th rib adjacent to the descending aorta (Figure 1). There was a small left hemothorax but no periaortic hematoma or evidence of aortic injury. A CT scan of her pelvis showed a right sacral ala fracture and a left superior ramus fracture. She had a calculated Injury Severity Score (ISS) of 5 and was transferred to our hospital 6 hours after the injury.

The patient was hemodynamically stable upon arrival at our institution and had a blood pressure of 132/77 mm Hg, heart rate of 75 beats per minute, and a score of 15 on the Glasgow Coma Scale. The patient was in moderate discomfort due to pain. Following review of the CT scans, different management options were contemplated; however, the decision was made to treat her expectantly, mostly due to her excellent condition many hours after the injury and the absence of any radiographic evidence of aortic injury. Her initial hematocrit was 37.1%, and a follow-up hematocrit several hours later was 31.4%. An interim chest radiograph showed no evidence of increasing effusion, but the patient was admitted to the surgical intensive care unit and a follow-up CT scan was ordered.

The next morning (nearly 24 hours after the injury), as the patient was being prepared for transfer to the CT suite, she coughed and immediately reported left-sided chest pain. Within minutes she became hypotensive to a blood pressure of 60/40 mm Hg. A left tube thoracostomy drained over 1 L of blood, and the patient momentarily regained a blood pressure above 90 mm Hg. As urgent preparations to move her to the operating room were being made, she lost vital signs, and an emergency left thoracotomy was performed at the bedside. Upon entry into the chest, a large amount of fresh blood was encountered and evacuated, and the aorta was cross-clamped. Her heart was empty and would not restart despite massage, intracardiac epinephrine, and defibrillation. A Foley catheter was placed in the right atrium for rapid infusion of blood, but to no avail.

Simultaneous examination of the de-scending aorta revealed a 2-cm ragged laceration adjacent to a sharp, isolated, protruding edge of the fractured 10th rib (Figure 2). The patient was pronounced dead. No other chest injuries were identified.

Discussion

It is understandable how a penetrating, on-blunt mechanism of injury can cause a fractured rib and descending aortic laceration, but one would think that the mechanism of injury must be significant to cause fracture and displacement of a rib at this posterior?almost paraspinal?location. As shown by our report, even seemingly minor mechanisms of injury can result in rib fracture and aortic laceration. Elderly patients with fragile osteoporotic ribs may be at particular risk. It is possible that aortic perforations from rib fractures are more common than currently thought but remain undiscovered because patients do not reach the hospital alive due to immediate exsanguination from the aortic laceration or from other associated injuries.

The literature contained six reports of aortic injury from a rib fracture in the setting of significant blunt trauma.1-6 All but one of those cases manifested in a delayed fashion (3 to 15 days after injury). The rib fractures were identified on hospital admission, and, in most cases, CT scans of the chest showed the rib fragment in close proximity to the aorta. In one case, a patient with an ISS of 4 underwent thoracoscopy 8 days after a fall from a tree for drainage of a left hemopneumothorax seen by chest radiograph only.1 Rib fractures were found, but no aortic injury or source of bleeding was observed at that time. One week later (post-trauma day 15), recurrent hemothorax prompted a repeat thoracoscopy, which was converted to a thoracotomy and revealed an actively bleeding aortic laceration at the site of a 9th rib fracture. The aorta was repaired primarily and the rib fragment was resected.

In another case, sudden shock developed 3 days after a motorcycle accident in a patient with an initial ISS of 9.2 During thoracotomy, an aortic laceration with a surrounding pseudoaneurysm was found adjacent to a sharp 6th rib fracture.2 Although it was clearly the source of a large hemothorax, it was not actively bleeding at the time of the operation. No CT scans of the chest had been done during admission.

A third case involved a motor vehicle collision where the patient sustained multiple bilateral rib fractures, which resulted in flail chest, lung contusions, and bilateral small hemopneumothoraxes requiring thoracentesis.3 The patient had an estimated ISS of 9, and sudden shock occurred 10 days after the injury following a "body position change." An emergency thora-cotomy identified an aortic laceration adjacent to the sharp edge of a fractured left 8th rib, which was repaired primarily.

The fourth reported case involved an 8-foot fall, and the patient had an ISS of 4.4 Aortic injury was identified by aortography, and a CT scan of the patient's chest showed the injury adjacent to a displaced left 6th-rib fracture. At initial presentation, a chest tube had been placed for a small left hemothorax. Seven hours later, after a "body position change," the chest tube suddenly drained over 1,000 cc of blood; the patient died on the way from the angiography suite to the operating room.

The fifth case resulted from a motorcycle accident.5 A left chest tube was placed for a small hemopneumothorax, and 11 days after injury, the patient became hemodynamically unstable during chest physiotherapy and the chest tube suddenly drained 2 L of blood. Emergency thoracotomy revealed a puncture site on the posterior aspect of the aorta, adjacent to the spiculated end of a fractured rib. The aorta was repaired primarily.

The last case involved a patient who presented in shock after a 15-foot fall.6 A left chest tube was placed for a large hemothorax, which drained more than 1,500 cc of blood. The patient was immediately transported to the operating room where thoracotomy revealed an actively bleeding aortic laceration adjacent to a rib fracture. The injury was repaired primarily and the rib fragment was resected.

Five of the six patients discussed were successfully resuscitated, and all but one demonstrated no evidence of aortic injury on admission. In these cases of delayed aortic bleeding, it is unclear whether the perforation of the aorta was present but sealed at the time of admission or if it occurred later due to movement or cough; the latter scenario may be more likely. If a laceration existed from the beginning, one would expect the initial CT scan to show evidence of aortic injury, such as a small pseudoaneurysm or periaortic hematoma. On the other hand, inspection of our patient's rugged laceration did not give the macroscopic impression of a fresh laceration.

The management of thoracic aortic injuries following blunt trauma is controversial. Although expectant management has been safely undertaken when foreign objects such as bullets or shrapnel are abutting large vessels, this strategy does not appear to be safe when rib fractures abut the aorta. On the other hand, a full thoracotomy might have unacceptable morbidity if the aorta is not found to be injured and the operation is done only to reduce one rib. Performing rib reduction or resection through a local extrapleural incision may be the optimal choice. This procedure can cause acute bleeding during manipulation of the rib, particularly if the edge of the rib is tamponading the laceration; thus, this operation must be performed with a team capable of rapidly opening the chest and addressing the bleeding. Unfortunately, even under the best circumstances, an aortic laceration bleeding freely into the thoracic cavity may produce death within minutes.

Conclusion

Our case of aortic laceration from a rib fracture is unique because it involved a patient who experienced a minor traumatic event and had few associated injuries. Although such cases are rare, when a fractured rib is abutting the aorta, catastrophic outcomes are possible even when there is no evidence of direct vascular injury. There is no ideal therapeutic option to treat such patients, but the risk-to-benefit ratio seems to indicate that reduction of the displaced rib under controlled circumstances in the operating room, fully prepared for a rapid thoracotomy, yields the best outcome.

References

Surg Today

1. Iyoda A, Satoh N, Yamakawa H, et al. Rupture of the descending thoracic aorta caused by blunt chest trauma: report of a case. . 2003;33(10):755-757.

J Trauma

2. Marco JV, Gregory JS. Posterior fracture of the left sixth rib causing late aortic laceration: case report. . 1997;42(4):736-737.

Nippon Kyobu Geka Gakkai Zasshi.

3. Kigawa I, Fukuda I, Fujii Y, et al. A sharp edge of the fractured ribs caused the aortic injury at body-position change: a case report [in Japanese]. 1992;40(7):1116-1120.

Changgeng Yi Xue Za Zhi.

4. Hsu YP, Chen RJ, Bullard MJ, et al. Traumatic thoracic aortic injury caused by a sharp edge of left fractured rib on body position change: case report. 1998;21(3):343-346.

J Trauma

5. Ashrafian H, Kumar P, Sarkar PK, et al. Delayed penetrating intrathoracic injury from multiple rib fractures. . 2005;58(4):858-859.

Am Surg

6. Kern JA, Chan BB, Kron IL, et al. Successful treatment of exsanguinating aortic injury from a fractured rib. . 1998;64(12):1158-1160.

Self-assessment questions

Choose the best answer for each question or incomplete statement.

1. Rib resection to prevent aortic injury should be considered in which one of the following patients? a) Those with a displaced protruding fracture of the left lateral 7th rib.

b) Those with a displaced protruding fracture of the right posterior 7th rib.

c) Those with a displaced protruding fracture of the left posterior 7th rib.

d) Those with a nondisplaced fracture of the right lateral 7th rib.

e) Those with a nondisplaced fracture of the left posterior 7th rib.

2. Injury to the aorta in the setting of a displaced rib fragment can occur at all of the following time points except: a) at the time of injury. b) after rib resection.

c) 1 day post-trauma, when resuming physical therapy.

d) 1 week post-trauma.

e) on admission to the emergency department.

3. Following penetrating injuries to the chest, emergency resuscitative thoracotomy at the bedside is indicated when: a) The blood pressure (BP) is less than 90 mm Hg even if the patient is mentating.

b) The BP is less than 70 mm Hg even if the patient is mentating.

c) The BP is more than 70 mm Hg but immediate chest tube output is higher than 2 L.

d) The BP is unrecordable for at least 30 minutes.

e) The BP is less than 60 mm Hg, the patient is not mentating, and the operating room transport time is more than 10 minutes.

4. Fractured and spiculated ribs can produce any of the following injuries except: a) Cardiac laceration.

b) Lung laceration.

c) Esophageal laceration.

d) Aortic laceration.

e) Diaphragmatic laceration.

»click to view answer