An isolated sternal fracture has extremely low mortality risk, but this rises rapidly with the presence of associated injuries.2 Associated injuries that contribute to this high mortality include flail chest, aortic injury, pulmonary and myocardial contusions, intra-abdominal injuries and head injury. Because of the heart’s location directly posterior to the sternum, cardiac complications such as myocardial contusion can occur with a fractured or displaced sternum.
History and clinical exam findings
Ask all patients with thoracic trauma about their mechanism of injury. If the patient can’t provide this information, interview bystanders or determine mechanism to the extent possible from clues on scene. Determine any preexisting medical conditions that could possibly complicate the patient’s ability to compensate for developing shock. Examples are the use of anticoagulant or beta-blocking medications along with any past medical history that can be complicated by traumatic insult, such as coronary artery or respiratory disease.
Patients with rib or sternal fractures will typically present with complaints of pain worsening with movement, coughing, inspiration and palpation, dyspnea, and tachycardia. The clinical exam will often reveal crepitus, pain with palpation, and guarding and splinting of the affected area. In addition, compressing the thoracic cage at a location away from the injury site may result in pain at the injury site, as intrathoracic pressure increases and irritates the injury.
Tachycardia will most likely be present because of associated pain; the patient may be tachypneic with a shallow tidal volume, as it often hurts to take deep breaths.
Tachycardia and tachypnea may also signal respiratory compromise from associated pneumo- or hemothorax. Soft tissue injury, such as a contusion, abrasion, erythema, ecchymosis or swelling, may also be present over the fracture site.
If a patient with fractures to the lower rib cage (ribs 9–11) presents with signs and symptoms of shock and does not have signs and symptoms suggesting tension pneumothorax or hemothorax, suspect an intra-abdominal injury (such as to the liver or spleen).
Transport patients with even simple, isolated rib fractures to an emergency department for evaluation. Specific management for rib fractures depends on the degree of respiratory impairment and centers around maintaining normal respiratory function and pain relief. Most often the patient with an isolated rib fracture will require only pain control during their injury management. Giving an IV analgesic such as fentanyl can alleviate the pain; consider it early in patient management. If the patient’s respirations are inadequate or signs of hypoxia exist, administer supplemental oxygen to maintain a pulse oximetry of at least 94%. Utilize positive-pressure ventilation (PPV) as necessary to maintain respiratory function.
Patients with even seemingly benign fractured sternums should receive full spinal immobilization and supplemental oxygen, be placed on cardiac monitors and have large-bore IVs established. Assess their cardiac rhythm frequently for signs of cardiac irritability in the form of PVCs, PACs and dysrhythmias, all signs of cardiac contusion. As with rib fractures, give IV analgesics for pain control if pain interferes with the patient’s ability to breathe adequately.
A flail chest is created when three or more ribs are fractured at two or more places each, creating a freely moving segment of chest wall that moves paradoxically to the rest of the chest. Flail segments can be located anteriorly, laterally or posteriorly, and a flail sternum can result from anterior blunt force trauma that disarticulates the sternum from all the ribs (costochondral separation).
Breathing is affected by flail chest in three ways: The work of breathing is increased, tidal volume is decreased, and pulmonary contusions interfere with respiration. The work of breathing is increased by the loss of integrity of the chest wall and the resulting paradoxical movement of the flail segment. Tidal volume is decreased both by the paradoxical movement of the flail segment compressing the lung on the affected side during inspiration, and also by the patient’s reluctance to take deep breaths because of the pain produced when the flail segment moves. In addition, a flail segment is almost always associated with underlying pulmonary contusion, resulting in atelectasis and poor gas exchange across the alveolar-capillary membrane. All of these factors contribute to developing inadequate respirations and hypoxia.