One in five Americans dies in the intensive care unit (ICU) or shortly after an ICU stay. Regardless of the precise age threshold used to define “elderly,” it is clear that a sizeable proportion of ICU patients are older adults. In the United States, those aged 65 years or older constitute nearly 50% of ICU admissions, a percentage which will grow considerably with the aging of the population. While the proportion of elderly ICU patients maybe higher in the United States than in other countries, most developed countries have seen substantial ICU use by patients older than age of 65 years. Importantly, most studies support that age alone is not an independent predictor of outcome in the ICU and that age should not be used as a criterion for determining which patients can “benefit” from intensive care. Rather, the key issue is the reversibility of the acute illness in the context of the overall health of the patient.
As a group, the elderly present with a unique set of challenges and opportunities for critical care providers. Many of these are well-defined and known, while others are poorly defined and relatively understudied. In this chapter, we briefly review some of the physiologic changes associated with aging and their implications for intensive care. We discuss some of the common admitting diagnoses and associated conditions seen in elderly patients and present data about outcomes of intensive care in the aged. We then explore interventions that may improve outcomes of intensive care, not only for patients, but for their loved ones as well.
Much has been written about the physiology of aging and the reader may refer to the Chapters in Part IV on organ systems for more detail for a thorough review of the topic. Rather than duplicate what has already been written, we focus on some of the key physiologic changes associated with aging and their implications for intensive care. These changes can be summarized as a gradual decline in organ function and physiologic reserve with an increased prevalence of chronic disease and vulnerability to disease.
The aging cardiovascular system can affect critical illness in two ways. The first is through increased prevalence of cardiovascular disease, which may be the primary reason for presenting to the ICU or a complicating factor when a patient with a noncardiovascular admitting diagnosis subsequently develops acute cardiovascular illness, such as cardiac ischemia. The second way cardiovascular disease can affect critical illness is through decreased cardiac reserve. Though this decrease may not be sufficient to alter daily activities in otherwise healthy subjects, the acute “stress test” of critical illness is often sufficient to make it manifest.
Maximal heart rate, ejection fraction, and cardiac output decrease with age, as does the responsiveness to sympathetic stimulation. The aging heart is therefore somewhat limited in its ability to increase cardiac output in response to stress, relying primarily on increased filling and stroke volume, rather than ...