Page 41 Complete Your CE Test Online - Click Here Innate immune system changes As discussed before, the innate immune system is comprised of macrophages, neutrophils, pattern recognition receptors (PRRs), and natural killer cells. Natural killer cells responsible for killing tumor cells and viruses have been found to be less active in older adults, according to a study of nursing home patients, resulting in increased infection and death from infection (Ogata et al., 2001). In older adults, macrophage activity and function is decreased, possibly leading to longer presence of bacteria in the body and delayed wound healing (Azar & Ballas, 2017). Neutrophil phagocytic ability in older adults is also decreased (Azar & Ballas, 2017). All of these factors lead to increased risk of infection and cancer and may result in the development of sepsis in older adults. Adaptive immune system changes The adaptive immune system includes T cells and B cells and is responsible for immune response to previous invaders. T cells are produced in the bone marrow and travel to the thymus gland to reach maturity. As aging occurs, there is less activity in the thymus gland, and the functional components of the thymus gland are replaced with fatty tissue, thereby resulting in fewer T cells (Azar & Ballas, 2017). B cells respond to invaders through exposure to infections or vaccinations by producing antibodies. The number of B cell precursors and the number of B cells decline with advancing age, as do specific antibodies produced from previous infections or vaccinations (Azar & Ballas, 2017). The decline in the adaptive immune system is responsible for the decreased effectiveness of vaccines in older adults. Decreased effectiveness of vaccinations Immune system changes in the older adult make vaccinations less effective, presenting a challenge to protect the health of a very vulnerable population. In patients > 65 years of age, a number of strategies have been used to combat this difficulty, such as increased dosage of a vaccine, increased vaccine boosters, and use of different vaccine formulations. Vaccinations remain crucial to the older adult to help ward off infections and viruses that may have serious health effects. It is recommended that the older adult, > 65 years of age, receive vaccinations to protect against influenza, pneumococcal infections, diphtheria, pertussis, tetanus, and zoster (Azar & Ballas, 2017). Nursing consideration: Nurses are likely to administer vaccines and are in a position to educate the public on the importance of being properly vaccinated to protect against infections that may lead to sepsis. Immunodeficiency A deficient immune response by the older adult may be, in part, due to the decreased response of the immune system as the body ages. The clinician should be aware that there may be an underlying immunodeficiency that is not simply a normal consequence of aging. If there is a increase in the length, severity, or frequency of infections or infections caused by unusual or opportunistic pathogens, an immunodeficiency should be suspected (Azar & Ballas, 2017). Causes of immunodeficiency include the following (Azar & Ballas, 2017): ● ● Malabsorption. ● ● Malignancy and related immunosuppressant therapies. ● ● Metabolic disease (diabetes, liver disease, uremia). ● ● Prescription drugs that may immunosuppress as a side effect. ● ● Malnutrition. Nutritional deficiencies in older adults Nutritional deficiencies in older adults contribute to the decreased effectiveness of the immune system and lead to susceptibility of developing infections and illness. Nutritional deficiencies exist for a variety of reasons. Older adults may not have the income necessary to buy healthy and nutritionally dense foods. Or they may not be able to prepare those foods for themselves because of physical or cognitive limitations. Many older adults live and eat by themselves, resulting in reduced caloric intake (Ritchie & Yukawa, 2017). Appetite tends to decrease with age, and elderly adults may simply not feel hungry. Problems with teeth, gums, or dentures and swallowing difficulties may also impair a person’s nutrition. Physical limitations, such as dysphagia (difficulty or discomfort swallowing), may affect those who have suffered a stroke or have such diseases as Parkinson’s, Zenker’s diverticula, and amyotrophic lateral sclerosis (ALS), thus reducing nutritional intake (Ritchie & Yukawa, 2017). Older adults may have difficulty or pain with chewing because of poor dentition. Or they may have tremors or other conditions, such as arthritis, that may make it difficult to feed themselves. Other conditions that may affect the intake of adequate nutrition include the following (Ritchie & Yukawa, 2017): ● ● Malignancy. ● ● Depression. ● ● Alzheimer’s disease. ● ● Gastrointestinal disorders (gastroesophageal reflux, celiac disease, inflammatory bowel, peptic ulcer disease, ischemic bowel, pancreatic insufficiency). ● ● Drug or alcohol dependence. ● ● Medication side effects. Vitamin deficiency Older adults are highly susceptible to vitamin deficiencies from either poor nutritional intake or poor absorption of vitamins that is a consequence of aging. Vitamin B12 deficiency is rather common in adults > 65 years of age, possibly affecting the nervous system (Ritchie & Yukawa, 2017). Nursing consideration: Nurses should identify anyone at risk for falls and should ensure proper fall precautions are in place. This can protect the patient from being injured and developing a subsequent infection that may progress to sepsis. Vitamin D is often deficient in older adults as well, resulting from such causes as poor intake and lack of sun exposure (Ritchie & Yukawa, 2017). Vitamin D is necessary for the absorption of calcium. A deficiency in vitamin D can lead to muscle weakness, increased risk of falls and fractures, and functional impairment (Bischoff-Ferrari, Dawson-Hughes, & Willett, 2004; Gerdhem, Ringsberg, Obrant, & Akesson, 2005; Milaneschi et al., 2010). If an adult is functionally impaired or at risk for falls and fractures, it stands to reason she is also at an increased risk for infection and development of sepsis. Calcium deficiency is also prevalent in older populations as a result of malabsorption by the gastrointestinal tract as a person ages (Ritchie & Yukawa, 2017). Adults between the ages of 70 and 90 absorb one-third the amount of calcium that younger adults absorb (Ritchie & Yukawa, 2017). Calcium deficiency is associated with reduced bone mass and osteoporosis, which can lead to osteoporotic fractures (Gennari, 2001). EBP alert! Osteoporosis affects more than 10 million people in the United States. Within that population, there are nearly 2 million fractures each year (National Osteoporosis Foundation, 2015). Comorbidities Older adults are more likely to suffer comorbidities than are younger adults. They may have preexisting conditions that put them at risk for infection, such as diabetes, cancer, kidney dysfunction, liver disease, and lung disease – among others. Older people are also more likely than younger adults to need invasive devices that have the potential of becoming infected, such as indwelling catheters, peripheral catheters, joint replacements, and pacemakers. These comorbidities may lead directly or indirectly to infection and increase the risk of morbidity and mortality of sepsis. In fact, chronic diseases – such as heart disease, lung disease, and diabetes – affect a person’s immune system more than their chronological age does (Mody, 2017). HAIs and CAIs Older adults are also more likely than younger adults to be hospitalized, live in long-term care centers, or participate in senior day care programs where they are highly susceptible to infection. They are also more likely to develop antibiotic-resistant infections in these care centers than in other sites. Methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), fluoroquinolone-resistant Streptococcus pneumoniae, and resistant gram-negative bacilli are more apt to affect this patient population than a younger population (Kupronis, Richards, & Whitney, 2003; O’Fallon, Schreiber, Kandel, & D’Agata, 2009).