The Injury Severity Score (ISS) is an anatomic, validated scoring system that is used to predict mortality.⁵ The ISS score is a value from 0 to 75. Each body area is graded for severity using the Abbreviated Injury Scale (AIS), and the sum of the squares of the scores of the three highest areas quantifies the overall injury (Table 2). Only the highest AIS score in each body region is used. Limitations of the ISS include difficulty calculating it during an initial evaluation, as the extent of injuries may not be appreciated. The ISS also does not take into account multiple injuries over a single body area. The New Injury Severity Score (NISS) was developed to include the three highest scores, regardless of anatomic area, and has been shown to be potentially more predictive of survival than ISS.⁶

Primary traumatic brain injury results directly from the traumatic event via tissue injury or hematoma formation. Secondary injuries, which are commonly iatrogenic, occur subsequently and include hypoxia, hypotension, seizures, fevers, and hypoglycemia, which impede recovery from the primary injury. Maintenance of euvolemia and normothermia will mitigate secondary injury.⁷ Traumatic cerebral edema generates increased intracranial pressures (ICPs) that can further injure the brain. Hyperosmolar therapy, hyperventilation, and elevation of the head of bed, may all aid in reduction of ICP. Hypertension and bradycardia in this setting suggest impending herniation, and immediate interventions are required based on the specific injury.

Chest injuries are very common in polytrauma patients. Chest injuries are painful and cause splinting and poor inspiratory effort in conscious patients. Recumbency results in poor ventilation, and narcotic medications suppress respiratory drive. Both increase the risk of pulmonary complications. Direct parenchymal lung damage
in patients with pulmonary contusions and other severe chest trauma will further diminish oxygenation within the days after injury. Tube thoracostomy will alleviate pneumothoraces and hemothoraces. Reduction and stabilization of axial and extremity fractures promote pain relief, upright posture, and mobility from bed, all of which reduce risks of pulmonary and other complications.

Rib fixation techniques have been recently described to provide mechanical support for ventilation and to relieve pain. Indications are evolving, but could include three or more ribs with severe bicortical displacement or within a flail segment.⁸ A recent study indicates less mechanical ventilation time, shorter hospital stay, less pneumonia, and lower mortality after rib fixation.⁸

Abdominal injuries occur commonly, and treatment over the past decade has become more nonsurgical.⁹ Selective angiography and embolization for solid organ injury, such as the liver or spleen, is also more common.¹⁰ Hepatic bleeding may be exacerbated by surgical exploration; however, some severe abdominal injuries may be better managed surgically. Persistent active bleeding within the spleen or kidney, pseudoaneurysms, or renovascular pedicle avulsions are surgical indications.

Very large forces are required to disrupt the stability of the pelvis. Associated injuries and blood loss depend on the fracture pattern, based on the direction of impact. Certain pelvic fractures can be associated with blood loss of several liters, related to magnitude of displacement of the posterior pelvic ring. Anterior-posterior compression injuries with complete disruption of the posterior ring or vertical shear injuries may be associated with life-threatening hemorrhage. Emergent circumferential pelvic reduction with a sheet or binder reduces the pelvic ring diameter toward normal and promotes tamponade of venous bleeding.¹¹ Distal femoral skeletal traction can further improve ring alignment for patients with cephalad displacement of one hemipelvis. In up to 10% of mechanically unstable pelvic fractures major arterial bleeding is present.¹² Such a patient will typically not respond to pelvis reduction and fluid resuscitation. Emergent angiography and embolization or pelvic packing are lifesaving measures.¹ Early reports suggest utility of resuscitative endovascular balloon occlusion of the aorta (REBOA) in reducing mortality from exsanguination after major intrapelvic, abdominal, and/or proximal lower extremity injury.^13,14 It can be a temporizing measure until arterial embolization or surgical control of hemorrhage is possible. Adverse consequences related to REBOA have been infrequently reported, including distal tissue necrosis and renal failure.

Open fractures, urogenital trauma, and gastrointestinal injury in conjunction with pelvic fractures are infrequent and are also considered surgical emergencies. Mortality of open pelvic fractures has been up to 50% in some studies. Control of bleeding by emergently packing open wounds is likely the most important initial measure unique to open pelvis fractures. Patients with posterior or perineal wounds or rectal trauma can be treated with a diverting colostomy to eliminate fecal contamination.¹⁵ Extraperitoneal bladder tears are often repaired if the patient receives open fixation of the anterior pelvic ring.¹⁶ Urethral injuries are diagnosed with retrograde urethrogram before attempting Foley catheter insertion. Catheter realignment, with or without endoscopic guidance, is the preferred definitive management of urethral tears.

Open fractures are classified by their severity of soft-tissue injury and amount of contamination (see Chapter 18).¹ Despite controversy regarding risk associated with surgical delay, urgent débridement and irrigation in the operating room is still recommended
and is generally combined with provisional or definitive fixation, as soon as is safely possible. Stabilization of an open fracture provides support to the surrounding soft tissues and decreases the risk of infection. Occasionally, provisional external fixation is preferred, because of massive contamination, surgical delay, or systemic instability, eg, severe hemorrhage or head injury.

Displaced fractures should be reduced and immobilized. Pelvic ring injuries with widening of the pelvic diameter and hemodynamic instability are reduced urgently via circumferential sheeting, but this treatment should also be considered for hemodynamically stable patients to reduce pain.¹¹ Femoral shaft fractures and some high-energy proximal femoral fractures benefit from application of skeletal traction to restore length and to provide relief of pain and spasm.¹⁷ Dislocated joints cause pain and may result in neurologic and/or vascular compromise. Dislocations should be reduced urgently when possible and stabilized as indicated to prevent recurrence. Closed reductions are possible in most cases; however, some dislocations are most safely undertaken in the operating room under general anesthesia to provide muscular paralysis and to promote safe airway management.

Expeditious reduction and fixation of fractures may promote control of hemorrhage and further resuscitation of the patient. Initial provisional reduction of pelvis, acetabulum, and extremity injuries as described above is followed with timely definitive care. A stable fracture is typically less painful and is beneficial to patient physiology. Pain induces sympathetic discharge, which can contribute to the hyper-inflammatory response of injury. Pain can also lead to poor respiratory effort and impaired ventilation; atelectasis ensues and may progress to hypoxemia or pneumonia. Therefore, pain control is essential, especially in the care of the multiply injured patient. Fracture stabilization can provide pain relief. Early fracture fixation of certain fractures has been associated with reduced narcotic medication intake, and potentially less respiratory depression and other adverse effects.^18,19

Fixation of certain fractures can also contribute to resuscitation. Reduction and fixation of pelvic ring injuries and long bone fractures reduces ongoing hemorrhage. There is evidence that fixation of these injuries as well as mechanically unstable thoracolumbar spine injuries and acetabulum fractures should also be expedited.^{19,20,21,22,23,24} Each of these injuries otherwise relegates a patient to lie recumbent in bed, further increasing their pulmonary and thrombotic risks. In stable patients evidence has emerged that these fractures are best definitively managed within the first 36 hours after injury.^{19,20,21,22,23} Even though some of the surgical approaches themselves may be associated with pain and bleeding, the net effect on patient physiology may be positive. Fixation is thought to promote mobility from bed, reducing risks of thrombotic complications, fat embolism, pneumonia, adult respiratory distress syndrome (ARDS), and sepsis. Multiple studies have documented the positive effects of early fracture management in general in diminishing morbidity and mortality.^{19,20,21,22,23,24,25,26,27,28,29,30,31}