INTRODUCTION AND EPIDEMIOLOGY
The elderly have worse outcomes following trauma because of physiologic changes that occur with aging. They are more susceptible to serious injury from low-energy mechanisms, less able to compensate from the stress of injury, and more likely to suffer complications during treatment and recovery. Emergency physicians should have a higher suspicion for injury and lower threshold for diagnostic testing and admission than in younger patients.
Studies have variously defined the lower limits of the geriatric age group to be as young as 55 years and as old as 80 years. Some have shown mortality to increase with individuals as young as 45 years of age.1 Regardless of the definition, caring for injured elders constitutes a large and growing portion of emergency medicine practice. The U.S. Census Bureau projects that those ≥65 years old will increase from 13% to 16% of the population by 2020 and to 20% by 2040.2,3 Geriatric patients represented 12% of the population in the Major Trauma Outcomes Study.4 Although the elderly are less likely to be involved in trauma, they are more likely to have fatal outcomes when injured, with a mortality rate twice that of younger patients. Those age 65 years and older consumed a disproportionate share of trauma hospitalizations (23%) and trauma costs (28%) relative to the 12% of the U.S. population they comprised in 1985.5
PATHOPHYSIOLOGY
Part of the difficulty in describing the elderly population derives from the discrepancy between chronologic and physiologic age. Chronologic age is the actual number of years the individual has lived, whereas physiologic age describes the functional capacity of the patient’s organ systems. Studies have shown a clear association between age and mortality. Comorbid diseases have been shown to be associated with increased mortality after minor and moderate injuries in all age groups.6
The physiologic changes of aging complicate recovery from injury and make assessment of injury more difficult. With age, myocytes are lost and replaced by collagen. This results in decreased contractility and compliance for any given preload.7 An 80-year-old person will have approximately 50% of the cardiac output of a 20-year-old, even without significant atherosclerotic coronary artery disease. Maximal heart rate and cardiac output decrease with age. Aging myocardium has a decreased chronotropic response to catecholamines and is dependent on preload (intravascular volume); hypovolemia can easily result in shock. Deterioration of the cardiac conduction system leads to atrial fibrillation and bundle-branch blocks. Medications, especially digoxin, β-blockers, and calcium channel blockers, impair the tachycardic response to catecholamines, both impairing the body’s inability to compensate for hemorrhage and making heart rate an unreliable predictor of hypovolemia.
Chest wall compliance, respiratory muscle strength, and the capacity for oxygen exchange all decrease with age. The response to hypoxia may decline by 50% and that to hypercarbia by 40%, such that the patient may not appear to be in respiratory distress despite impending respiratory failure.8 Because of weakened respiratory muscles and degenerative changes in the chest wall, maximum inspiratory and expiratory force may be decreased by up to 50% compared with younger patients. Age-related reductions in vital capacity, functional residual capacity, and forced expiratory volume can limit older patients’ ability to compensate for chest injuries.
Renal function declines with age, predisposing patients to dehydration, requiring medication dose adjustments based on calculated creatinine clearance, and making them susceptible to contrast-induced nephropathy.
Falls are the most common cause of fatal and nonfatal injury in people ≥65 years of age.9,10 One third of older adults fall annually, and the rate of falls increases with age. Hip fractures are the most common fracture in elders hospitalized for injury, but the overall incidence of nonhip, nonspine fractures in women >55 years old is five times greater than hip fractures.11,12 There are age-related changes in postural stability, balance, motor strength, coordination, and reaction time that make the elderly more prone to tripping and falling. Other causes of falls in the elderly are listed in Table 255-1. Bathroom falls are concerning because hard bathroom surfaces can result in head and spinal injuries, and slippery surfaces can cause falls. Falls on stairs involve higher energy and potential for injury than those on flat ground. Falls in which an individual is unable to get help for a prolonged period should prompt investigation for rhabdomyolysis and dehydration with a check of the creatinine kinase and electrolytes.
Associated with syncope/loss of consciousness
Associated with near-syncope, positional change, vasodilation (e.g., hot water)
Nonsyncopal, “mechanical” causes
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Motor vehicle crashes are the second most common cause of injury in the elderly and are the leading cause of death, with a case fatality rate twice that of those under 65 years.4 The elderly make up 17% of U.S. traffic fatalities.13
The elderly are second only to children as victims of pedestrian–motor vehicle collisions. Those ≥65 years old account for 19% of pedestrian–automobile fatalities in the United States.14 Pedestrian–motor vehicle collisions are one of the most lethal mechanisms of injury in this age group, with a 53% case fatality rate.
There is a direct relationship between age and burn mortality, as evidenced by the traditionally taught Baux score, in which the sum of age and body surface area burned yield the percentage likelihood of mortality. Although the Baux score still has prognostic value, advances in critical care and burn treatment have raised the point of futility of treatment to a Baux score of 160 (rather than 100) and a 50% risk of mortality to a Baux score of 110.15 In patients >65 years old, a 50% mortality is anticipated with a body surface area of burn of 28%. The presence of inhalation injury adds the equivalent of 17 years or points of body surface area burned to the predictive score.16
Maintain a high suspicion for intentional injuries and injuries caused by neglect. Warning signs include poor hygiene, untreated decubitus ulcers, injuries not explained by the reported mechanism, and subacute injuries in various stages of healing.
CLINICAL FEATURES
Treat injured elders as both trauma and medical patients. Ask the patient, family, and prehospital care providers about the exact events leading up to the injury. Avoid skipping the review of systems, past medical history, and medications list. Investigating the cause of a fall may uncover serious underlying medical causes or prevent future trauma.
Avoid feeling reassured by “normal” vital signs. A tachycardic response to pain, hypovolemia, or anxiety may be absent or blunted in the elderly trauma patient. Medications such as β-blockers may mask tachycardia and hinder the evaluation of the elderly patient. One study demonstrated that eight of 15 geriatric blunt trauma patients initially considered to be hemodynamically “stable” had cardiac outputs <3.5 L/min, and none had an adequate response to volume loading. Of seven patients with normal cardiac outputs, five had inadequate oxygen delivery.17 Another study reported that 39% of patients with a systolic blood pressure >90 mm Hg and heart rate <120 beats/min had occult hypoperfusion, defined by lactate >2.2 or base deficit less than –2.18 The elderly also have blunted responses to hypoxia, hypercarbia, and acidosis, which can mask the signs of respiratory failure.
Blood pressures are also misleading in the elderly patient. Because of the high incidence of underlying hypertension approaching 90%, the clinician must use a higher cutoff for hypotension than in younger patients. In blunt trauma patients ≥65 years old, there is an association between hypotension and mortality starting with systolic blood pressures below 110 mm Hg and heart rates above 90 beats/min. Therefore, it is reasonable to use these more conservative cutoffs as markers of abnormal vital signs.19 A decrease in blood pressure of 30 mm Hg below a known baseline or a falling trend is also a marker of instability.
Remain highly concerned about the elderly patient with abnormal vital signs. One study found that geriatric trauma patients with a respiratory rate <10 breaths/min had 100% mortality.20 Likewise, a systolic blood pressure <90 mm Hg in the elderly blunt trauma patient is associated with a mortality between 82% and 100%.21
Anatomic variations may complicate airway management. These include the presence of dentures (which may occlude the airway and make laryngoscopy more difficult), cervical arthritis (which adds danger to extending the neck), or temporomandibular joint arthritis (which may limit mouth opening).
A thorough secondary survey is essential to uncover less serious injuries. Patients with no apparent life-threatening injuries can have potentially fatal injuries if there is some degree of limited physiologic reserve. Seemingly sTable geriatric trauma patients can deteriorate rapidly and without warning. Undertake a medication review early in the patient’s evaluation, paying particular attention to medications that affect heart rate, blood pressure, and coagulation.
DIAGNOSIS
Head injuries in the elderly cause almost 142,000 United States ED visits resulting in discharge, 82,000 survivable hospitalizations, and 14,000 deaths annually.22 Age is an independent predictor for morbidity and mortality in patients with moderate or severe head trauma. When evaluating the patient’s mental status, it would be a grave error to assume that alterations in mental status are due solely to dementia or senility.
Elders are less prone to develop epidural hematomas than the general population because of the denser fibrous bond between the dura mater and the inner Table of the skull. There is, however, a higher incidence of subdural and intraparenchymal hematomas in the elderly than in younger patients. As the brain mass decreases with age, there is greater stretching and tension of the bridging veins that pass from the brain to the dural sinuses. Bridging veins are more susceptible to traumatic tears. Diagnosis of intracranial bleeding may be delayed because brain atrophy increases intracranial free space, allowing blood to accumulate without initial signs or symptoms.
One study of blunt head trauma patients taking warfarin who were experiencing no or minimal symptoms found a rate of injury on head CT that changed disposition in 7%.23 Therefore, immediate noncontrast head CT is recommended for patients who take warfarin and have a mechanism of injury concerning for even a minor head injury. Check the INR, because the degree of anticoagulation correlates with the risk of adverse outcomes.24 The risk conferred by other anticoagulant medications is less known. Some studies have shown the antiplatelet medication clopidogrel to confer an increased risk of intracranial bleeding after head injury.25 There is insufficient evidence to delineate the risk conferred by aspirin, low-molecular-weight heparins, or the newer oral anticoagulants.26,27
The incidence of cervical spine injury is about twice as great in elders as in a younger cohort of blunt trauma patients. Odontoid fractures are particularly common in geriatric patients, accounting for 20% of geriatric cervical spine fractures, as compared with 5% of nongeriatric fractures.28 Preexisting cervical spine pathology, such as osteoarthritis, bulging discs, and osteoporosis, may predispose elderly patients to spinal cord injuries. With hyperextension injuries, elderly patients may develop a central cord syndrome, which causes motor deficits in the upper extremities more often than the lower extremities, variable sensory loss, and bladder dysfunction. The Canadian Cervical-Spine Rule, but not the National Emergency X-Radiography Utilization Study criteria, excludes patients age ≥65 years from being considered low risk for cervical spine injury.29,30 Thus, liberal imaging of the cervical spine in geriatric trauma patients is warranted. Because of the higher pretest probability of injury, as well as the difficulties in interpreting plain radiographs in a patient with age-related degeneration, CT scan is the preferred initial modality for assessing the geriatric cervical spine. Many fractures in one section of the spine are accompanied by fractures in another section, so identification of one fracture should prompt imaging of the entire spinal column.31
Thoracic and lumbar spine fractures account for almost half of all osteoporotic fractures.32 They are most common at the thoracolumbar junction (T12-L1) and midthoracic areas (T7-T8).33 Anterior wedge compression fractures are the most common. Because of the low sensitivity of plain films for identifying thoracolumbar fractures in trauma patients, CT scan is the first-line imaging modality for adult patients.34
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