The Geriatric Patient

Jay A. Yelon

INTRODUCTION

According to U.S. census projections the elderly population, defined as age >65 years, is experiencing the largest growth in history. The post–World War II “baby boom” (75 million people born from 1946 to 1964) was 46–64 years old in 2010. By the year 2030, the elderly population will number 38 million and will usher in the gerentological explosion by 2050 in which 1 in 5 Americans will be elderly.¹ The overwhelming evidence of this demographic imperative will result in an elderly population that is active and vital. The ever-increasing mobility and active lifestyles of today’s elderly place them at increased risk for serious injury. In fact, data from the National Trauma Data Bank (NTDB) for the year 2008 revealed that 30% of all patients in the registry were 55 years old or older.² Injury is now the fifth leading cause of death in the elderly population.³

Older individuals sustaining injury respond differently than younger patients. The elderly have a higher morbidity and mortality, have more preexisting medical problems, and demonstrate a senescent physiologic response to injury when compared with younger individuals. Many of the reasons for the differing response are unknown. The literature, albeit plentiful, can be contradictory in places and there are few prospective randomized trials that focus specifically on the elderly. This is best demonstrated by a lack of consensus on the definition of what age constitutes elderly. Historically geriatric patients were considered to be patients over the age of 65 years. There are a variety of organ-specific injuries that demonstrate rising morbidity and mortality at chronological ages less than 65 years. As such, elderly should be viewed from the vantage of the physiologic response to an injury or injury complex rather than a specific age. Despite these limitations, this chapter will focus on an overview of care for the injured geriatric patient.

AGING

Declining cellular function is part of the aging process. Eventually, this will lead to organ failure. The aging process is characterized by impaired adaptive and homeostatic mechanisms, resulting in increased susceptibility to the stress of injury. This is commonly perceived as decreased physiologic reserve. Insults commonly tolerated by younger patients can lead to devastating results in the elderly patient. Differences in the metabolic response to injury were studied by Frankenfield and colleagues. In their study, they compared injured patients by dividing them into those older than 60 years and those who were younger. These investigators concluded that the metabolic response to injury is significantly attenuated in the elderly population. This was demonstrated by the older group having less fever, less oxygen consumption, more hyperglycemia, and more azotemia.⁴ This may be driven by the fact that there is evidence that immune function is significantly attenuated during the aging process and that cytokine response is impaired. This immune senescence is, in part, a function of reduced neutrophil function. Butcher et al. investigated a group of patients older than 65 years sustaining mild trauma (hip fracture). Neutrophil phagocytic function was assessed immediately after injury and patients were followed for 5 weeks for clinical infection. When compared with a younger cohort, the older patients had a significant reduction in neutrophil phagocytic function as measured by significantly depressed superoxide production.⁵ Additionally, nearly half of the elderly population suffered bacterial or fungal infection within the study period, compared with no infection in the younger patients. These authors suggest that the aging immune system may be a result of falling dehydroepiandrosterone (DHEA). In the presence of the physiologic stress of injury, patients have an obligatory rise in corticosterone levels, which is immune suppressive. The elderly patient, with a depressed DHEA level, produces a milieu of corticosterone excess contributing to neutrophil dysfunction.

ORGAN FUNCTION AND AGING

Cardiac

Cardiovascular comorbidities are most frequently seen in the elderly patient. Cardiac function declines by 50% between the ages of 20 and 80 years. The declining function is combined with a decreased sensitivity to catecholamines.⁶ The expected cardiovascular response to hypovolemia may not be apparent. This may be further complicated by a variety of medications, which includes β-blocker therapy.⁷ The cellular elements of the conductive system and the myocytes themselves are gradually replaced by fat and fibrous tissue. The resultant stiffer heart is more prone to dysfunction and to dysrythmias. Atherosclerotic changes to the arteries are common and valvular anatomy is changed by tissue thickening. The increased afterload causes an increase in systolic blood pressure and enlargement of the heart. The system is generally well compensated while at rest. However, in the event of hypovolemia, elderly patients generally are unable to compensate with tachycardia and an increase in cardiac output. The response is generally characterized by an increase in systemic vascular resistance. Traditional vital signs can be misleading. Despite “normal” blood pressure, many of these patients have evidence of tissue hypoperfusion.⁸

Pulmonary

There are significant anatomic and physiologic changes that occur in the respiratory system that are associated with aging. Grossly, with age-related loss in bone density, there is development of thoracic kyphosis. Rib calcification is associated with a decrease in transverse thoracic diameter. Muscle mass is reduced and the elastic recoil of the lung decreases with age. These anatomic changes result in a decreased compliance of the chest. Reduction in functional residual capacity and gas exchange is obligatory.⁹ The elderly commonly experience decreased cough reflex, decreased function of the mucociliary epithelium, decreased response to foreign antigen, and increased oropharyngeal colonization with microorganisms. These changes place the elderly patient at risk for hospital-acquired pneumonia.¹⁰

There is a decrease in alveolar surface area after the age of 30 years. This results in decreased alveolar surface tension that ultimately interferes with alveolar gas exchange. The alveoli are also noted to flatten and become shallow, thereby decreasing effective surface area for gas exchange. Diffusion capacity is decreased because of the decrease in effective surface area and an increase in alveolar–capillary membrane thickness.¹¹

Renal System

Above the age of 50 years, renal mass is lost. Progressive sclerosis of the glomeruli occurs with normal aging. Between the ages of 50 and 80 years, there is a decrease in glomerular filtration rate (GFR) by about 45%.⁶ Generally, this is not detected by routine renal function testing, as it is accompanied by a decrease in total muscle mass and production of creatinine. The Cockroft–Gault formula can be used to estimate the degree of dysfunction. Furthermore, the endocrine response of the kidney to ADH and aldosterone is abnormal. This results in a decrease in the ability of the kidney to concentrate urine. Elderly patients may be able to maintain a deceptively adequate urine flow despite hypovolemia. As such, urine output should be used cautiously as a surrogate for renal perfusion.^12,13

These age-related changes in renal function put the older patient at significant risk for acute kidney injury following trauma. Likewise, the elderly are at risk for developing untoward effects of aggressive volume resuscitation—such as hyperchloremic metabolic acidosis and volume overload. Care must be maintained when dosing renally excreted drugs to these patients.

Skin/Soft Tissue and Musculoskeletal System

Older people undergo an obligatory loss of lean body mass. This loss is estimated to be about 4% every 10 years after the age of 25. This loss then increases to approximately 10% after the age of 50. The loss of muscle is accompanied by a proportional increase in adipose tissue. From a skeletal aspect, osteoporosis is a common feature of aging. Over time, this loss can amount to 60% of trabecular bone and 35% of cortical bone.¹⁴ This makes the elderly individual at risk for fractures, especially those involving the vertebrae, hip, and distal forearm. There are age-associated changes of the joints and cartilages resulting in osteoarthritis and other degenerative features affecting nearly all joints. Degenerative changes to the cervical spine are particularly worrisome in the older population. Mobility is greatly affected putting this area at risk for injury. Additionally, oral intubation can be affected by this loss of mobility.¹⁵

Changes of the skin and soft tissue with loss of elastin and subcutaneous fat not only place the patient at risk for direct skin injury but may also complicate underlying fractures, such as pelvic fractures or open fractures.

Endocrine

There are age-related changes that affect endocrine function. The tissue responsiveness to thyroxin and its production is reduced.⁶ Secretion of cortisol does not seem to change with aging, but given decreases in DHEA production, this may predispose the physiologically stressed elderly patient to a hypercortisone state.

Functional Reserve

Maintaining homeostasis in the face of physiologic stress is a demonstration of good functional reserve. Declining functional reserve in the elderly may precipitate a decline in performance when the patient is exposed to chronic or acute illness. When faced with a physical insult, homeostasis may be poorly maintained (Table 44-1; Fig. 44-1).

TABLE 44-1 Organ System Changes with Aging

FIGURE 44-1 The functional reserve is the difference between basal function (red line) and maximal function (blue line). Even in healthy individuals, this functional reserve is reduced. (From Muravchick S. Geroanesthesia: Principles for Management of the Elderly Patient. St. Louis, MO: Mosby; 1997, with permission. Copyright © Elsevier).

The decline in functional reserve is heterogeneous. A variety of factors will impact on the magnitude of the loss of functional reserve. These include age-related disease and their treatments, genetics, lifestyle choices, and environmental factors. It is clear that older patients do not tolerate injury as well as younger patients. What is not clear is the reason for this discrepancy. The impact of preexisting medical problems,^16–18 in combination with a declining functional reserve, results in poor outcome. This impact on outcome can be reduced by an aggressive management approach to the patient.

MANAGEMENT

Triage

Improper triage seems to contribute to the poor outcomes experienced by some elderly trauma patients. The effectiveness of triage can be evaluated by looking at the interaction between injury severity and complication rate, mortality, or requirement for intervention.¹⁹ Elderly patients with severe injury who are not treated with full trauma team activation (TTA) would be considered to be undertriaged. Multiple studies have shown a large incidence of undertriage as compared with younger patients.^19–22 Undertriage can be viewed as a modifiable risk factor for poor outcome in the older patient. Lehmann et al. demonstrated that the classic physiologic criteria for TTA, that is, blood pressure and heart rate, failed to independently predict hospital mortality or the need for urgent interventions.²⁰ These authors attribute the older patient’s “pseudostability” to declining functional reserve and the interaction of premorbid medications. Use of initial vital signs in the elderly population can be misleadingly normal. In a study from Los Angeles patients 70 years of age and older admitted to the trauma center were reviewed. Sixty-three percent of patients with an Injury Severity Score and 25% of patients with an did not meet the hypotension or tachycardia criteria for TTA. In this study, the overall mortality in “stable” patients not meeting any of the standard TTA criteria was 16%.¹⁹ The impact of apparently “minor” injury can have major impact on the older patient. Rib fractures and pulmonary contusions can lead to an abrupt decompensation and injuries such as intracranial hemorrhage are commonly underappreciated. It has been suggested that patient age of 70 or older be used as a criterion for TTA.¹⁹ The age at which triage and management issues become problematic is also controversial. The current recommendation of the ATLS program is 55 years of age.²³ This is based on data from the Major Trauma Outcomes study that noted a significant increase in mortality between the 45- and 54-year-olds.²⁴ TRISS uses a similar age cutoff, although a recent work examining TRISS methodology seems to indicate an older age is more accurate. Caterino et al., using the Ohio trauma registry, examined mortality trends. Regression analysis identified 70 years of age to be the most promising cutoff for predicting increased odds of mortality.²¹

Initial Assessment

Airway

The elderly airway poses specific challenges for providers. Given the fact that the elderly have significant loss of protective airway reflexes, timely decision making for establishing a definitive airway can be lifesaving. Patients may have dentures or be edentulous, the former making bag–mask ventilation easier. Arthritic changes may make mouth opening difficult. Choice of appropriately sized direct laryngoscopy equipment is mandatory. When performing rapid sequence intubation the doses of barbiturates, benzodiazepines, and etomidate should be reduced between 20% and 40% to minimize the risk of cardiovascular depression.²⁵

Breathing

The anatomic and physiologic changes in the respiratory system associated with aging are reviewed above. Changes in the compliance of both the lungs and the chest wall result in an increased work of breathing with aging. These changes associated with the possibility of nutritional deficits and the supine position place the elderly trauma patient at high risk for respiratory failure. Given a suppressed heart rate response, as a result of aging, to hypoxia, respiratory failure may present in a more insidious fashion. Diagnosis can sometimes be difficult in interpreting clinical and laboratory information in the face of preexisting respiratory disease or nonpathologic changes in ventilation associated with age. Frequently, decisions to secure a patient’s airway and provide mechanical ventilation may be made prior to fully appreciating underlying premorbid respiratory conditions. This action may be lifesaving. However, intubation and mechanical ventilation in the elderly patient should not be taken lightly. The risk of ventilator-associated pneumonia and the possibility of prolonged ventilation are significant.²⁵ The role for noninvasive mechanical ventilation in the acute resuscitative phases of trauma care seems to be very limited and is likely associated with significant risk to the patient.

Circulation

Age-related changes in the cardiovascular system place the elderly trauma patient at significant risk for mislabeling the patient as being “hemodynamically normal.” Since the elderly patient may have a fixed heart rate and cardiac output, response to hypovolemia will occur by increasing systemic vascular resistance. To further demonstrate the lack of classic symptoms as they relate to cardiovascular pathology, Chong and colleagues evaluated troponin I levels following emergency orthopedic surgery. One hundred and two patients over the age of 60 were evaluated, of which 52.9% of patients had elevated levels. The majority of patients with elevated troponin levels had no cardiac symptoms and had an increased mortality within 1 year of the event. Furthermore, since many elderly patients have preexisting hypertension, the seemingly “acceptable” blood pressure may truly reflect a relative hypotensive state. As such, identifying the patient who has significant tissue hypoperfusion is mandatory. Several methodologies have made, and continue to be used to make, this diagnosis. These include base deficit, serum lactate, age-adjusted Shock Index, and tissue-specific end points.^8,26–28 Resuscitation of the geriatric hypoperfused patient is the same as all other patients and based on appropriate fluid and blood administration. The elderly trauma patient with evidence of circulatory failure should be assumed to be bleeding. However, given the incidence of elderly people with preexisting disease states, one should keep in mind that some physiologic event may have triggered the incident leading to injury. Ultimately an aggressive approach to resuscitation of the elderly patient with overt shock or a tissue-hypoperfused state will result in acceptable outcomes. Less aggressive measures based on the patient’s age are not acceptable.

Disability

Traumatic brain injury (TBI) is a problem of epidemic proportion in the elderly population.²⁹ Older age is a known variable for poor outcome following brain injury. Aging will cause the dura to become more adherent to the skull. Additionally, older patients are more commonly prescribed anticoagulant and antiplatelet medications for preexisting medical conditions. These two factors place the elderly individual at high risk for intracranial hemorrhage. Atherosclerotic disease is common with aging and may contribute to primary or secondary brain injury. Moderate cerebral atrophy will permit intracranial pathology to initially present with a normal neurologic examination. Early identification and timely appropriate support including correction of therapeutic anticoagulation can improve outcomes.³⁰

Exposure

Musculoskeletal changes associated with the aging process pose special concerns during this aspect of the initial assessment of the elderly trauma patient. Loss of subcutaneous fat, nutritional deficiencies, chronic medical conditions, and the associated medical therapies will place the elderly patient at risk for hypothermia and the risks associated with immobility (pressure ulcers, delirium). Rapid evaluation and, when possible, early mobilizations will prove to minimize the morbidities.

SPECIFIC INJURIES

Traumatic Brain Injury

In the elderly age group, TBI accounts for more than 80,000 emergency department visits each year of which a majority result in hospitalization. Falls are the leading cause of TBI for people over the age of 65 years (51%), followed by motor vehicle collisions (9%).²⁹ Health care costs associated with the treatment of TBI in the elderly exceeded $2.2 billion in 2003.³¹ TBI is clearly a major health care problem in the elderly population. The current evidence-based approach to treating severe TBI in the adult is a “one size fits all” approach, neglecting specific issues of the older adult. Old age remains an independent predictor of worse outcome in TBI. An investigation using the New York State Trauma Registry compared mortality and functional outcome in elderly versus younger patients.³² In this study, Susman et al. demonstrated increased mortality in patients older than 65 years, but also showed that mortality increases as patients continue to age. These investigators also showed that a majority of elderly patients sustain TBI from falls and appear to have only mild TBI at admission and still had a much higher mortality as compared with younger patients. This same group then looked at the total effect of age on mortality after TBI.³³ They concluded that mortality from TBI increases after 30 years, but has a sharp rise after 70 years. Given the anatomic changes associated with aging on the brain and the fact that a majority of elderly patients present with a GCS consistent with mild brain injury, a high index of suspicion must be maintained with the elderly patient presenting with any mechanism of head trauma. To address this, Mack et al. investigated the use of head computed tomography (CT) in elderly patients.³⁴ This study specifically looked at mild head injury (GCS 13–15). In their study of 133 elderly patients, 14.3% had radiographic evidence of acute intracranial pathology. The authors also noted that there were no useful clinical predictors of intracranial injury and liberal use of head CT is recommended. Despite a higher mortality in general, patients surviving hospitalization will required aggressive rehabilitation. In a multi-institutional trial a group of elderly patients surviving their initial moderate to severe brain injury (head AIS = 3) were evaluated following discharge from acute care. In this cohort, there were few patients with low GCS who survived, and left patients with GCS of 13–15 to be evaluated. Functional outcome for these patients, as measured by the Glasgow Outcome Scale (GOS) and modified FIM, is good to excellent. Older patients required more inpatient rehabilitation and took longer to recover when compared with a younger patient cohort.³⁵ Aggressive initial management and long-term rehabilitation in the elderly patient with TBI is required for acceptable outcomes.

Rib Fractures

Rib fractures in the elderly population pose a significant risk for morbidity and mortality when compared with younger patients, who, in general, suffer little morbidity. The morbidities include inadequate pain management, need for intubation, prolonged ventilatory support, and the development of pneumonia. Bulger et al. investigated the impact of rib fractures after blunt chest trauma in the elderly.³⁶ This study showed a linear relationship between age, number of rib fractures, complications, and mortality. In a similar study, Holcomb et al. retrospectively evaluated 171 patients. These authors demonstrated an increase in negative outcomes based on increasing age and number of rib fractures. By grouping ages and number of rib fractures their data revealed that patients with more than four rib fractures who are older than 45 years exhibit increased morbidity (ICU length of stay [LOS], total LOS, ventilator days, and pulmonary complications). Given the impact of type of analgesia at reducing ventilator days and pulmonary complications, the authors attempted to determine the impact of epidural analgesia. Their data were unable to demonstrate a decreased incidence of morbidity and mortality. Given that this was only a portion of their entire population, it is possible that their results suffer from a type II statistical error. Analgesia is an important aspect of the care of the elderly trauma patient with rib fractures. The Eastern Association for the Surgery of Trauma has a Practice Management Guideline on chest trauma analgesia management.³⁷ Readers are encouraged to refer to this document on evidence-based guidelines for analgesia. In an evaluation of data from the NTDB of the American College of Surgeons Committee on Trauma, Flagel et al. reviewed a large patient population.³⁸

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