Trauma in Older Adults

Timothy F. Platts-Mills and Sasha D. Adams

The increase in the number of active and independent older US adults has led to an unfortunate corresponding increase in the proportion of older trauma patients (1). Common mechanisms of injury in older adults include falls, motor vehicle collisions, and recreational activities (2). Although geriatric patients currently account for 10% to 15% of all trauma in the United States, it has been projected that this will increase to nearly 40% by 2050 (3,4). This is important because injury patterns and physiologic responses to injury differ between older and younger adults. Further, older trauma victims consume more health care resources, account for more health care expenditures, and have worse outcomes after trauma than younger individuals (5).

Approximately 28% of all traumatic deaths in the United States occur in adults of age 65 or older, and trauma is the fifth leading cause of mortality among geriatric patients. The case-fatality rate for adults of age ≥65 ranges from 15% to 30% versus 4% to 8% for those <65 years of age (4,6). Though there is evidence to suggest that risk of poor outcome from trauma begins to rise as early as age 40, the risk of death clearly increases after age 65 (7). Despite the risk associated with trauma in older adults, it is important to recognize that survival can be improved through early, aggressive management (6).

CLINICAL PRESENTATION

Injury severity is an important factor in the outcome of older trauma patients. The extent of injury is determined in part by the causal mechanism, but, for similar events, the severity of injury tends to be greater for older than for younger individuals. For example, falls from height and pedestrian-struck incidents are three to four times more likely to result in death for older adults than younger adults and account for nearly 50% of trauma deaths in older adults (8,9). The disproportionate increase in severity among older patients is attributable to a combination of age-related anatomic and physiologic changes. Pre-existing medical conditions, present in approximately 40% of those of age 65 to 74; 65% of those of age 75 to 84; and 90% of those of age ≥85, compromise older adults’ response to injury, as does polypharmacy (10).

Pathophysiology

Cardiovascular

Myocyte degeneration leads to a progressive loss of cardiac function with aging (decrement in cardiac index ∼1% per year), which limits the ability of older individuals to maintain cardiac output in the presence of diminished filling pressure (10). This is further impaired by a decrease in the number and responsiveness of β-adrenergic receptors and fibrosis of the conduction system, which diminish the chronotropic and inotropic response to catecholamine stimulation. Coronary artery disease may exacerbate the situation by limiting oxygen delivery to the remaining functional myocardium, increasing the risk of ischemia and subsequent cardiac decompensation. Concurrent stiffening of peripheral vessels from atherosclerosis and a general increase in systemic vascular resistance (∼1% per year) also occur. This works to preserve blood pressure despite a reduction in forward flow but also results in diminished compliance, which increases susceptibility to injury by shearing forces.

These changes and concurrent use of antihypertensive medications create a cardiovascular system that is less responsive to the drop in intravascular volume that can occur with trauma. Older patients often do not develop tachycardia in response to hypovolemia, and those with hypertension at baseline may experience a substantial drop in blood pressure without meeting usual criteria for hypotension. As a result, abnormal vital signs are an insensitive indicator of life-threatening injury in older trauma patients, and triage systems should not rely solely on vital signs to identify high-risk patients (11).

Pulmonary

A decline in chest wall elasticity and lung compliance occurs with aging, leading to reductions in functional vital capacity and forced expiratory volume and an increase in residual volume (10). By limiting air movement, these alterations enhance the potential for carbon dioxide retention during periods of hypoventilation and barotrauma with positive-pressure ventilation. Because mucociliary clearance is also diminished, there is an increased risk of mucous plugging from secretions and pneumonia from bronchial obstruction. A progressive loss of alveoli is known to occur as well, which causes a decrease in diffusion capacity and arterial oxygen tension, manifesting as an age-dependent decline in the partial pressure of oxygen. Such changes are strongly potentiated by a history of smoking.

Injuries to the chest wall and lung can impair respiratory mechanics and dramatically increase the work of breathing. As such, they are not well tolerated in older adults. Older patients are particularly susceptible to rib fractures (estimated incidence, ∼60%), which may occur even with minor force.

Renal

Renal function diminishes with advancing age due to a combination of progressive glomerular loss and decreases in renal blood flow. This results in a steady decline in glomerular filtration rate (GFR) and consequently, creatinine clearance. Serum creatinine concentration, however, does not accurately assess renal function, particularly in older individuals who have significantly reduced muscle mass. Direct measurement of creatinine clearance or estimation of GFR using validated formulae, therefore, is the preferred method for quantification of renal function in the older trauma patient. In addition, these effects can be exacerbated by chronic diuretic use or suboptimal fluid intake with a resultant chronic hypovolemia.

Older patients are at high risk for deterioration in renal function even from brief periods of hypoperfusion. During the initial care of the injured older adult, the benefits of ensuring adequate renal blood flow by providing additional fluid must be balanced against the negative effects of aggressive fluid resuscitation, which may exacerbate uncontrolled hemorrhage, accelerate coagulopathy, and increase risk of pulmonary edema (12). Although urine output is considered a useful marker of renal perfusion in younger patients, it is less reliable in older individuals (13). This is due to a progressive reduction in urine concentrating ability, which permits ongoing production of seemingly adequate amounts of dilute urine even in the face of significant hypovolemia. Caution should also be exercised when using agents that have known nephrotoxic effects, particularly nonsteroidal anti-inflammatory medications and intravenous contrast agents.

Musculoskeletal

Osteoporosis is present to some degree in most older individuals, making them highly susceptible to fractures, and it is six times more prevalent in women than in men (14). The bones of the hip, wrist, and spine are at greatest risk and may be injured with minimal force. A seemingly straightforward fracture may result in substantial morbidity and risk of death in the older patient. Fractures often require operative fixation, subjecting the older patient to perioperative complications, whereas nonoperative therapy limits mobility and puts the patient at risk for skin breakdown, pulmonary embolus, and pneumonia. Pain medication, difficulty bearing weight, and mobility equipment devices may worsen balance, resulting in a high risk of falls and injury during the recovery period.

Dermatologic

Thinning of the epidermis, loss of dermal blood vessels, flattening of the dermal–epidermal junction, collagen degeneration, and loss of subcutaneous tissue all occur with aging and increase the likelihood of damage when frictional or compressive forces are applied to the skin (10). These changes also slow wound healing, which increases the potential for infection and reduces the effectiveness of temperature autoregulation.

Neurologic

Progressive brain atrophy and dural adherence to the skull occur with aging. These changes lead to an increase in the subdural space surrounding the brain, and a stretching of the parasagittal bridging veins, making them more prone to rupture. As a result, older adults have a propensity for the development of subdural hematoma after head trauma; the rate is nearly two times that of younger patients (4.4% vs. 2.4%) (15). Because of brain volume loss, a substantial amount of blood can accumulate in the subdural space without producing a mass effect, leading to an increased risk of a delay between the time of injury and onset of symptoms. Cerebral contusions are also slightly more common in older than in younger adults. In contrast, epidural hematomas and depressed skull fractures are rarely seen (estimated prevalence of 0.5% and 0.2%, respectively) (10).

Mechanisms of Injury

Falls

Falls are responsible for the majority (∼60%) of trauma in older adults. Falls in older adults often reflect underlying pathology or result from medication side effects. Falls commonly result in hip fractures, and an older adult with hip pain after a fall should be presumed to have a hip fracture. A negative plain radiograph does not exclude hip fracture, and computed tomography (CT) or magnetic resonance imaging (MRI) should be obtained in patients for whom hip fracture is suspected but not seen on plain films.

Vehicle-Related Accidents

Automobile collisions and injuries of pedestrians are the second and third most common causes of trauma in older adults, respectively, with the former accounting for an estimated 250,000 US ED visits each year (2). Though most older drivers modify their driving habits as they age (i.e., driving at slower speeds, driving shorter distances, and avoiding driving at night and in adverse weather conditions), older drivers have the highest rate of fatal collisions of any age group. Factors that contribute to vehicle crashes in older drivers include slower reaction times, decreased visual fields, sensory or cognitive deficits, distractions, and medications. Though older drivers are less likely to use drugs or alcohol than younger drivers, impaired driving may also be a factor.

Ambulatory limitations, gait disturbances, and sensory deficits (especially visual and auditory) place older adults at particular risk for being struck by an automobile. Older pedestrians who are struck are more likely to suffer injury, particularly of the head, chest, spine, pelvis, and tibia (9). Of those who survive the initial impact, in-hospital mortality exceeds 25%—nearly four times that of younger patients (9).

Burns

Thermal injuries in older adults are responsible for 13% of all burn unit admissions in the United States. Burns in the geriatric population are associated with extensive tissue damage and significant morbidity as many of these individuals do not have the reflexes, muscle strength, or motor coordination to move away from the source of heat until substantial injury has occurred. In addition, wound healing is slowed in older adults, increasing potential exposure to nosocomial infection and prolonging the time to recovery. Increased age is an independent risk factor for mortality after burn, and the sum of age in years and the percentage of body area burned can be used to estimate burn-related mortality (16).

Penetrating Trauma

Penetrating trauma is responsible for 5% to 10% of all traumatic events that occur in older adults versus 25% to 45% in younger adults (17). Though injuries are generally similar in location and severity to other age groups, firearm injuries in older adults are more likely to be self-inflicted, particularly if the individual is a white male. Penetrating trauma in the geriatric population is associated with prolonged intensive care unit (ICU) and hospital stays.

Neglect or Abuse

Neglect or abuse is a pervasive problem among older adults (18). Risk factors for abuse include a shared living situation, social isolation from friends and relatives, physical impairments, dementia, and exposure to perpetrators with a history of mental illness or substance abuse. Because caretakers and victims may deny or minimize the extent of the problem, cases are often difficult to recognize. Warning signs for abuse and neglect include delays in seeking medical attention, inconsistent history between caregiver and patient, unexplained injuries (fractures or bruising), discrepancy between history and physical examination findings and diagnostic testing, severe malnutrition, and poor hygiene.

Common Injury Patterns

Head

Closed head injuries are common in older adults, and the head is the most common body area to be severely injured. The incidence of traumatic brain injury and intracranial hemorrhage is increased in those of age ≥65 who sustain closed head trauma (12.5% vs. 7.9% in the National Emergency X-Radiography Utilization Study [NEXUS] II), and outcomes are worse, particularly for those in whom the presenting Glasgow Coma Scale (GCS) is ≤8 (in-hospital mortality 53% to 76%) (19,20). Because >75% of these events are related to ground level falls, the history and initial examination can be falsely reassuring. Typical “low-risk” criteria (i.e., absence of loss of consciousness or a GCS of 15) do not exclude intracranial injury in older adults. Both of the large validated instruments designed to determine the need for head CT scan after minor trauma identify advanced age as a criterion for obtaining a head CT (21). Thus, liberal use of CT is recommended for older individuals with closed head trauma. This is particularly true for those on antiplatelet or anticoagulant medications. Patients on these medications with evidence of intracranial hemorrhage require rapid and complete correction of their anticoagulation to prevent progression of brain injury (22).

Spine

The incidence of cervical spine injuries doubles in older adults, with a particular increase in the occurrence of C1 and C2 fractures (23). As with head trauma, the majority of cervical spine trauma in older adults results from ground level falls (23). Although the Canadian C-spine Rule includes age ≥65 as an independent “high-risk” criterion that mandates radiographic assessment for all older trauma patients, the NEXUS criteria do not include age and have been validated in a geriatric cohort (13).

Although spinal cord injury itself is rare, older adults are at increased risk for central cord syndrome owing to a high prevalence of underlying spondylosis and a greater likelihood of cervical hyperextension related to a fall. Classic findings of central cord syndrome include upper motor neuron weakness (arms > legs, distal > proximal) and variable sensory deficits. These patients are at risk for progression of symptoms and must be admitted and closely observed.

Fractures of the thoracic and lumbar spines are also relatively common and may be present in 40% of patients with identified injuries of the cervical spine. They often manifest as anterior wedge compression fractures, particularly in older females with underlying osteoporosis (14). Though neurologic complications are infrequent, such fractures can be a source of debilitating pain. Plain film radiographs or CT are usually sufficient for initial evaluation, but subsequent investigation using MRI or bone scanning may be required to identify occult fractures in those with persistent discomfort.

Chest and Abdomen

Pneumothorax, hemothorax, and pulmonary contusion should all be considered early in the evaluation of the older patient with thoracic trauma. Rib fractures in particular are a marker of more severe injury and are associated with a 19% increase in the risk of death. Initial evaluation with a single-view chest radiograph is appropriate but may not delineate subtle rib injuries, underlying lung contusion, or small pneumothoraces. CT should be considered in those with a nondiagnostic chest x-ray and significant discomfort, physical examination findings, or respiratory difficulty.

Abdominal trauma in older adults results in injury patterns similar to those in younger patients. Prompt recognition of hemoperitoneum is critical as older individuals do not have the physiologic reserve to withstand large-volume blood loss. Though initial screening with ultrasound is reasonable, negative results should be interpreted with caution, particularly for those with significant abdominal pain. Patients with pain or tenderness should be further evaluated using CT.

Pelvis and Extremities

Fractures of the proximal femur and pelvis are common in older individuals and most often result from a ground level fall. Among pelvic fractures, lateral compression fractures predominate, and 75% involve injury to the pubic rami or acetabulum. As compared to younger patients, older patients with pelvic fractures experience complications such as hemorrhage more commonly, require angiography and ICU admission more frequently, and have an increased risk of death. Owing to trabecular bone thinning, falls that impact the hips and pelvis are more likely to result in injury to the femoral neck and greater trochanter than to the pelvic bones themselves. Falls with the upper extremity in extension may result in fracture to the distal radius or the proximal humerus.

DIFFERENTIAL DIAGNOSIS

Though the consequences of trauma in older adults often require immediate attention, it is essential to consider the precipitating event, particularly in patients with unwitnessed or poorly described falls or those involved in single vehicle collisions. Life-threatening medical conditions such as cerebral vascular accidents, transient ischemic attacks, myocardial infarctions, malignant cardiac dysrhythmias, and critical electrolyte abnormalities could have precipitated the event and should be considered in all older trauma patients. Some individuals, particularly those who reside in assisted living facilities, may have advanced dementia or other neuropsychiatric conditions that preclude verbal communication. For these patients, discussion with primary caregivers and prehospital personnel regarding the circumstances of the event, pre-existing medical conditions, and baseline medications should be pursued. Involvement of a social worker or adult protective services is necessary if abuse or neglect is suspected.

ED EVALUATION

The initial evaluation and resuscitation of the older trauma patient closely parallels usual trauma protocols. Adequacy of airway protection and respiration should be assessed immediately. Older patients are prone to develop hypoxia, and supplemental oxygen should be administered upon presentation. To avoid precipitous decompensation, early intubation should be considered in those with significant thoracic injuries. For patients who require intubation, care must be taken to limit manipulation of the oropharynx and hyperextension of the neck. Broken dentures, if present, should be removed to prevent further injury, but intact dentures may facilitate bag-valve-mask ventilation and should be left in place until definitive airway control is achieved.

Early identification of hypoperfusion in the older trauma patient is also critical and should be assessed simultaneously with the assessment of airway and breathing. As noted earlier, usual indicators (i.e., heart rate >100 beats/min and systolic blood pressure <90 mm Hg) are insensitive markers of hypovolemia in older adults, and significant hypoperfusion may be present in patients without tachycardia and with systolic blood pressures of 90 to 130 mm Hg. Thus, for all patients with suspected intra-abdominal injury, a bedside focused assessment with sonography for trauma (FAST) should be completed to determine the presence of intra-abdominal hemorrhage and laboratories should be obtained to identify occult reductions in tissue oxygen delivery (24). Impaired perfusion as indicated by a base deficit greater than 6 mEq/L or a lactic acid concentration ≥2.4 mmol/L correlates with greater trauma severity and mortality and is more sensitive than vital signs for identifying life-threatening injuries (15). Worsening of the base deficit or failure to clear lactic acid on serial measurement are particularly ominous signs and should be considered indicative of insufficient resuscitation or developing complications (i.e., blood loss or ischemia).

Advanced hemodynamic monitoring has been shown to be particularly beneficial in older trauma patients, reducing complications of hypoperfusion, including multiorgan system failure, and improving survival (6). Parameters such as cardiac output, systemic vascular resistance, and oxygen delivery and consumption can be measured, and targeted resuscitative efforts using crystalloid fluids, vasopressors, and inotropes can be initiated. Although pulmonary artery catheterization is the time-honored method, noninvasive technology such as thoracic bioimpedance and near-infrared spectroscopy can provide equally accurate data with lower risk and cost. Bedside cardiac ultrasound is a useful adjunct in differentiating volume deficiency versus cardiac dysfunction as causes of hypotension. Patients with low output and elevated preload can be rapidly evaluated for pericardial effusion, and a rough quantification of cardiac function can be determined (10).

Radiographic evaluation of the older trauma patient may need to be delayed if the patient is hemodynamically unstable. However, once the airway has been addressed and access obtained, it is usually possible to perform cross-sectional imaging simultaneously with resuscitation and monitoring. Most, if not all, patients with head trauma (regardless of mechanism or degree of injury) should undergo head CT, especially if they are taking anticoagulants or antiplatelet medications. Plain films have been the traditional method of radiographic assessment for potential cervical spine injury, but CT has emerged as the modality of choice for initial evaluation in those with high-risk mechanisms, altered mental status or intoxication, suspicious clinical findings, or anatomic variants likely to limit plain film interpretation. Head CT has the added advantage that it can be performed concurrently with other CT scans. Patients with abnormalities on CT or a clinical suspicion of spinal cord injury despite a normal CT require MRI. Given the high prevalence of concomitant injuries, x-rays or CT of the entire spine should be obtained in individuals with cervical spine fractures, even in the absence of physical examination findings.

As previously noted, there should also be a low threshold for ordering CT to evaluate for potential thoracoabdominal injuries. Moreover, although plain films may be adequate for the evaluation of most musculoskeletal injury, further imaging with CT or MRI may be required in patients with negative x-rays but persistent pain. This is particularly important for hip fractures, which may be occult in up to 5% of cases. For patients with signs or symptoms suggestive of a life-threatening injury, the initial evaluation and treatment should be coordinated with a trauma surgeon-intensivist, preferably in a trauma center (25).