chapter 36 The Geriatric Patient*

When the United States was founded, life expectancy was about 35 years. By the mid-1800s, it had increased to nearly 42 years. In 1950, life expectancy jumped to 68 years. As of the year 1991, the average life expectancy was 75.5 years. The Census Bureau has projected that by the middle of the twenty-first century, more than 40% of people aged 65 at that time can be expected to live to the age of 90 years. Dentists can expect to be treating increasing numbers of elderly patients as the life expectancy increases and individuals maintain or prosthetically replace their natural dentition.

Classically, age 65 is considered the beginning of the geriatric period. This is an arbitrary age cutoff that is thought to originate from two independent sources, the first of which was Imperial Germany. The Bismarck government decided that they had only enough money for those 65 years of age and older. The second source was a group of English physicians who decided to care exclusively for the elderly. They decided, based on population alone, that they would have time for only those older than 65 years.¹

The geriatric population as a group is split into three parts: young-old, ages 65 to 74; old, ages 75 to 84; and oldest-old, age 85 and older. In 1998, 12.7% of the general population was 65 and older, and 1.5% was 85 years and older. California has the largest population numbers of persons older than 65, but Florida has the distinction of being the state with the largest percentage of residents older than 65 (18.3%).²

It is important to remember though, that no matter what age is chosen as the beginning of the geriatric phase, everyone ages in two ways: chronologically and biologically.¹ This makes elderly individuals a physiologically diverse group since there is no correlation of biologic age with chronologic age because of the effects of concomitant diseases.

Almost 75% of young-old persons (in 1992) who were not institutionalized considered their health to be good, very good, or excellent, compared with almost two thirds of individuals older than age 75.³ It has been found that an individual’s perceived health is very important. Persons with chronic disease were more likely to die if they considered themselves to be in poor health compared with those who believed themselves to be in good health despite the presence of chronic disease.³ At the time of the 1990 census, individuals reaching the age of 72 years or more made up the oldest 5% of our population. By the year 2000, that age had increased to 80 years.⁴

Although more people live to advanced age, they do so with increasing illness and disability. Many have diseases, such as arthritis, diabetes, osteoporosis, and senile dementia. These chronic diseases are partially responsible for the functional limitations that some elderly individuals experience. Functional limitations may include difficulty with walking, getting outside, dressing, and other activities of daily living. Individuals with mild impairments usually are living within the community. As individuals acquire more impairments, the likelihood that they will be living in a care facility increases. The active life expectancy becomes an important concept in thinking about elderly individuals. The definition of active life expectancy is the expected years of physical, emotional, and functional well-being.⁵

The top five causes of death in elderly individuals are heart disease, malignant neoplasms, cerebrovascular disease, pneumonia and influenza, and chronic obstructive pulmonary disease (COPD). As individuals age, heart disease accounts for a larger percentage of the deaths (about 44% of deaths in individuals aged 85 years and older).^6,7

The aging process involves both physiologic and pathologic changes that may alter patients’ ability to respond to stress and their response to drug administration (Table 36-1). Changes that occur with aging include a decrease in lean body mass, an increase in body fat (more so in women), and a decrease in total body water (more so in men).⁴ As a result, the geriatric patient has a smaller central compartment (decreased body water), the rapidly equilibrating compartment is smaller (decreased lean body mass), and the slowly equilibrating compartment is larger (increased body fat).⁴ The overall effect is that when a medication is given intravenously, there will be higher peak concentration because of the smaller central compartment. The volume of distribution should also be increased because of the body fat increases, and there may also be a longer duration of drug effect.⁴ The question now is whether geriatric patients really have changes in their pharmacodynamics (what the drug does to the body), or is it that there are changes in the early-phase pharmacokinetics (what the body does to the drug) that make the elderly patient seem more sensitive to medications?⁸

Table 36-1 Physiologic and Pathologic Changes in Geriatric Patients

Organ System	Anatomic Changes	Functional Changes
Body composition	Increased lipid fraction Loss of skeletal muscle and other components of lean body mass

Nervous system Cardiovascular system Pulmonary system Renal system Decreased plasma flow, glomerular filtration rate, drug clearance, and ability to handle salt and water loads Hepatic system Reduced tissue mass Reduced hepatic blood flow and drug clearance

From Miller R: Effects of aging on body composition and major organ systems. In Miller R, ed: Anesthesia, ed 4, New York, 1994, Churchill Livingstone; and Muravchick S: Anesthesia for the elderly. In Miller R, ed: Anesthesia, ed 4, New York, 1994, Churchill Livingstone.

Adverse drug interactions are more common in elderly patients than in younger patients. One reason is that geriatric patients take more medication, medication to control the symptoms of age-related diseases. Approximately half of adults aged 75 years or older take at least two diff/>