Phases
Host (individual)
Agent (motor vehicle)
Environment
Pre-event (will event occur)
Age, gender, medications, alcohol use, vision, fatigue, ambulatory aids/ability
Speed, size, ability of driver, brakes
Road design, crosswalk design and timing, weather conditions, visibility, speed restrictions, traffic restrictions
Event (will injury occur)
Age, preexisting conditions (e.g., osteoporosis), medications (e.g., bleeding risk)
Speed, size, brakes
Site of crash, landing zone
Post-event (will consequence occur)
Age, comorbid conditions
Ability to extricate
Availability of EMS, distance from emergency care, quality of trauma system and rehabilitation
Advanced age is a well-recognized risk factor for morbidity and mortality after trauma [6]. There are many well-documented systems-based changes that occur with aging (these will be discussed in detail elsewhere in this text) that result in increased frailty and decreased physiologic reserve among elderly trauma patients. These physiologic changes are associated with the presence of more preexisting medical conditions and are associated with increased morbidity and mortality. These changes not only affect outcomes but may also contribute to the occurrence of a traumatic event (deteriorating visual acuity, poor balance, and gait disturbances).
Despite these physiologic changes and the associated increased morbidity and mortality among elderly trauma patients, the well-described trimodal distribution of death (Fig. 23.1) due to trauma still applies. This distribution demonstrates that deaths among trauma victims occur in one of three periods [7, 8]. Approximately 50 % of deaths occur within minutes of the injury and are most often the result of severe neurologic (brain, high spinal cord) injury or massive hemorrhage (aortic or great vessel disruption or cardiac rupture). These individuals almost universally die at the scene or on the way to the hospital and based on the injury pattern are not salvageable even in the most mature EMS and trauma systems. The second peak occurs over minutes to several hours and is usually due to subdural or epidural hematomas, tension pneumothorax, or injuries associated with significant hemorrhage such as splenic or liver laceration and severe pelvic fractures. These patients require rapid assessment, resuscitation, and treatment of the underlying life-threatening injuries (i.e., craniectomy, needle thoracostomy, or application of a pelvic binder) to improve survival. The third peak occurs over several days to weeks and is most likely due to sepsis and multisystem organ failure. Efforts at the rapid identification and treatment of underlying injuries and subsequent insults such as infectious, cardiac, and pulmonary insults will impact this later peak of trauma-related deaths [8].
Fig. 23.1
Trimodal distribution of traumatic deaths. Note: Immediate deaths are the result of devastating brain injuries, spinal cord injuries, aortic injuries, etc. Early deaths (within the first several hours) are often due to epidural or subdural hematomas, hemopneumothorax, pelvic fractures, abdominal injuries, and uncontrolled hemorrhage. Late deaths (weeks after injury) are the result of sepsis and multisystem organ failure
Overview of Injury
Unintentional injury is the fourth leading cause of death over all age groups, both sexes, and all races in the USA in data published from 2013 [9]. For patients 65 years and older, unintentional injury is the eighth leading cause of death [9]. In 2013, over 54,000 people 65 or older died from injuries in the USA that is a rate of nearly 122 deaths per 100,000 persons. To put this into perspective, nearly 150 elderly people are injured every day with one sustaining injury nearly every 9 min [9]. The leading mechanisms of injury in order from most frequent to less frequent are falls, pedestrians struck by motor vehicles, and motor vehicle crashes (Fig. 23.2) [9].
Fig. 23.2
Most common injury mechanisms among the elderly. Note: Falls are by far the most common mechanism of injury (nonfatal and fatal) among the elderly (66 %). Motor vehicle collisions and pedestrians struck make up the next most common mechanism overall (7.4 % each), while all other mechanisms combined comprise 19.2 % of all injury in this age group. Information calculated from data provided on http://www.cdc.gov/injury/wisqars/leadingcauses.html
Although the total number of traumatic injuries in the elderly is less than the total number of traumatic injuries in those between the ages of 18 and 45 years, the rate (or risk) of injury per age group is just the opposite. Those 65 years and older are at the highest risk of fatal injuries, a risk that increases with each year of age. From 2013 data, the rate of injury death in those 65–74 years old was 61.5 per 100,000 population; for those 75–84 years, it rose significantly to 127.5 per 100,000; and for those 85 years and older, this rate increased to 361.9 per 100,000 population. These values compare to 58 per 100,000 for the general adult population [10].
Nearly 15 % of the total US population is comprised of people 65 years and older. However, the elderly population accounts for 34.7 % of injury-related hospitalizations and nearly 30 % of all injury-related deaths [11]. With the unprecedented increase in the elderly population projected over the coming years, there will be profound implications on health and trauma care as the burden of geriatric injury will also surely increase at a similar rate.
Mortality is not the only potential consequence of a traumatic event. The morbidity associated with injury can be just as devastating of a consequence and has significant and widespread sequelae such as personal, family, societal, and financial repercussions that negatively impact quality of life and incur astronomical financial burden for both immediate and long-term medical care. In 2013, over 865,000 people 65 years and older were hospitalized as the consequence of an injury, while over 2.9 million elderly people are treated and released from the emergency department. Among the elderly, the leading causes of nonfatal injuries are as follows: unintentional falls, pedestrian struck, unintentional overexertion, and motor vehicle collisions. Total lifetime costs associated with nonfatal injuries in those 65–84 years of age occurring in the year 2010(the most recent year these data are available) amount to over $36.8 billion. This cost for nonfatal injuries includes direct medical expenditures ($20.9 billion) as well as the value of lost work productivity ($16.0 billion) but does not factor in the cost of pain, reduced quality of life, or the reduction in years lived [12].
Injury by Mechanism and Intent
Traumatic injuries are classified by their mechanism, their intent, and the place of injury. Mechanism refers to the external agent or activity that caused the injury (e.g., fall, motor vehicle collision, stab wound). Intent is classified as unintentional, intentionally inflicted on someone or undetermined. The place of injury can be classified as urban, suburban, or rural as well as location in the country.
Falls
Falls are the most common mechanism of injury (both fatal and nonfatal) among the elderly. Falls have been estimated to account for over two-thirds of unintentional injuries in 2013. Falls are the most common cause of nonfatal injury in the geriatric population and result in nearly 2.5 million emergency department visits and over 657,000 hospitalizations in the year 2013 [12]. In the USA, each year more than one-third of individuals over the age of 65 will experience a fall and increases to over 50 % for those individuals who live in an institution [13, 14]. Over half of those who suffer a fall will have at least one more unintentional fall within the next 12 months [15, 16]. Of these, it has been demonstrated that 25 % will be injured, and another 25 % will restrict their daily activities due to a fear of falling [17, 18].
In 2013, 84 % of fall-related deaths were among those aged 65 years and older. The rate of falling and being injured increases with age. The rate of fall injuries for adults over the age of 85 is four times the rate for those between the ages of 65 and 74 years. Women are 50 % more likely than men to suffer a nonfatal fall injury, with fall-related fractures twice more likely in women than in men [17, 19]. White females are twice as likely as black females to suffer a hip fracture. Up to 30 % of the elderly will suffer a moderate to severe injury such as a laceration, hip fracture, or head injury [17, 20].
Falls are the most common cause of traumatic brain injury (TBI) in the geriatric population [21]. Over 50 % of fall-related deaths in the elderly population are the result of a TBI [22]. Falls from a standing position is associated with a 5 % risk of hip fractures. This risk increases significantly with age. The consequences of a hip fracture can be devastating as 50 % of those who suffer a hip fracture are no longer able to live independently [23].
Major risk factors for falls among the elderly include those related to the host (intrinsic factors) and include advanced age, history of previous falls, hypotension, dementia and the use of psychoactive medications, postural instability and gait disturbances, decreased visual acuity, and other cognitive, neurologic, and physical impairments. Environmental (extrinsic) factors include loose rugs, objects on the floor, ice or slippery surfaces, uneven floors, poor lighting, and stairs without handrails. While intrinsic factors are significant risk factors for sustaining a fall, the risk of falling increases linearly with each additional extrinsic factor that is present [23].
Motor Vehicle Collisions
There are 36.8 million licensed elderly drivers in the USA, a 27 % increase from 2004. In comparison, the number of total licensed drivers (all age groups) only increased by 7 % over the same time period. Motor vehicle collisions (MVCs) are the second most common mechanism of fatal injury in persons 65 years and older and account for 15 % of unintentional deaths in 2013 [12]. Additionally, there were over 197,000 nonfatal injuries (5 % of total nonfatal injuries) among the elderly population [24]. In 2013, over 17 % of all traffic-related fatalities (5671 deaths) occurred in adults 65 years and older [25].
While drivers in their teens and twenties are at the highest risk of fatal and nonfatal injuries from MVC, drivers over the age of 75 have the highest risk of dying from their injuries [26]. Drivers 85 years and older have the highest rate of fatality (27.85 fatalities per 100,000 drivers), while the rate is lower among younger drivers (10–15 fatalities per 100,000 drivers) [27]. In two-vehicle fatal crashes involving an older driver and a younger driver, the vehicle driven by the elder was 1.7 times more likely to be the one struck (58 % and 34 %, respectively). In 46 % of these crashes, both vehicles were proceeding straight at the time of the collision. In 24 %, the older driver failed to yield to oncoming traffic while turning left, four times more often than the younger driver [28].
In general, older people drive fewer total miles, drive less at night, and drive mostly on the weekdays. Additionally they spend more time on familiar roads and drive at lower rates of speed. For these reasons, most elderly traffic fatalities occur in the daytime (75 %) and on weekdays (69 %) and involve a second vehicle (65 %) [27].
Injury patterns in the elderly are similar to those that are seen in the general blunt trauma population. Risk factors in the elderly that may contribute to MVCs include a larger blind spot (secondary to decreased peripheral vision), limited cervical mobility, slower reaction times, poorer technique for merging into traffic, decreased hearing, and cognitive impairment. Moreover, chronic medical conditions such as dysrhythmias, hypoglycemia (diabetes-related complications), and thromboembolic events such as stroke or myocardial infarction may be the precipitating event that leads to the collision. As with any driver, alcohol and impaired function lead to an increased risk for crash. Compared to all drivers, older drivers involved in fatal crashes are the least likely to be legally intoxicated (defined as a blood alcohol concentration of 0.08 g/dL or greater) (older 7 % vs. 18–64 years 23 %) [27].
Major factors that contribute to the likelihood of a crash include vehicle speed, vehicle stability, braking deficiencies, inadequate road design, and driver alcohol intoxication. When a collision does occur, important determinants of the likelihood of injury and injury severity include speed at impact, vehicle safety features (airbags), and the use of restraints. It should be noted that over three-quarters of older occupants of motor vehicles involved in fatal crashes were using restraints at the time of the collision compared to 64 % for other adult (18–64 years old) occupants [27, 29].
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