Aspiration Pneumonia in Older Adults
Aspiration pneumonia refers to an infection of the lung parenchyma in an individual that has inhaled a bolus of endogenous flora that overwhelms the natural defenses of the respiratory system. While there are not universally agreed upon criteria, the diagnosis can be made in patients with the appropriate risk factors and clinical scenario, in addition to a radiographic or an ultrasonographic image of pneumonia in the typical dependent lung segment. Treatment options for aspiration pneumonia vary based on the site of acquisition (community-acquired aspiration pneumonia [CAAP] versus healthcare-associated aspiration pneumonia [HCAAP]), the risk for multidrug-resistant (MDR) organisms, and severity of illness. Hospitalized CAAP patients without severe illness and with no risk for MDR organisms or Pseudomonas aeruginosa (PA) can be treated with standard inpatient community-acquired pneumonia therapy covering anaerobes. Patients with CAAP and either of the following—risk factors for MDR pathogens, septic shock, need for an intensive care unit (ICU) admission, or mechanical ventilation—can be considered for broader coverage against anaerobes, methicillin-resistant Staphylococcus aureus (MRSA), and PA. Severe aspiration pneumonia that originates in a long-term care facility or HCAAP with one or more risk factors for MDR organisms should be considered for similar treatment. HCAAP with one or more risk factors for MDR organisms or PA, plus septic shock, need for ICU admission or mechanical ventilation should receive double coverage for PA in addition to coverage for MRSA and anaerobes. Multiple gaps in current understanding and management of aspiration pneumonia require future research, with a particular focus on antibiotic stewardship.
© 2019 Society of Hospital Medicine
Aspiration pneumonia refers to an infection of the lung parenchyma in an individual who has inhaled a bolus of endogenous flora that overwhelms the natural defenses of the respiratory system. It primarily affects older adults with almost 80% of cases occurring in those 65 years and older.1 Compared with nonaspiration pneumonia, aspiration pneumonia (whether community acquired or healthcare associated) results in more ICU stays, mechanical ventilation, increased length of hospital stay, and higher mortality.2
The etiology of aspiration pneumonia comes from aspirated bacteria from the oropharynx or stomach.3 However, aspiration alone is a common occurrence and does not always lead to clinical pneumonia. Indeed, one study demonstrated that 45% of “normal subjects” aspirate in their sleep,4 illustrating that our bodies have evolved defense mechanisms to protect us from aspirated bacteria. Thus, it is only when these systems are overwhelmed, after compromise of both glottic closure and the cough reflex in addition to dysphagia,3 that an infection manifests.
ASPIRATION PNEUMONITIS
Aspiration pneumonitis refers to a significant inflammation of the lung parenchyma that results from inhalation of regurgitated gastric contents.5 It can produce fever, cough, wheezing, shortness of breath, hypoxemia, leukocytosis, and a pulmonary infiltrate as well as lead to severe acute respiratory distress syndrome and even death. In the past, the use of antibiotics shortly after aspiration in patients who develop a fever, leukocytosis, or a pulmonary infiltrate was discouraged.5 Empiric antibiotics were recommended only for patients who aspirate gastric contents and who have conditions associated with colonization of gastric contents, such as small-bowel obstruction.5 Yet, it is difficult to distinguish aspiration pneumonitis from pneumonia6 and there are no randomized trials in older adults to help guide their management.
PRESENTATION OF ASPIRATION PNEUMONIA
Pneumonia in older adults can present in an atypical fashion. In one study of community-acquired pneumonia (CAP), the combination of cough, fever, and dyspnea is present in only 31% of patients, although separately, they are present in 67%, 64%, and 71% of patients, respectively. The same study also showed that delirium was present in 45% of patients with CAP.7 Nonrespiratory symptoms were present during the initial presentation of CAP in 55% of patients, with confusion in 42%, and falls in 16% of cases.8 The same is true of aspiration pneumonia where altered mental status is seen in approximately 30% of community-acquired aspiration pneumonia (CAAP) patients and in 19% of continuing care facility patients with aspiration pneumonia.2 Another study that compared CAP, CAAP, and healthcare-associated aspiration pneumonia (HCAAP) showed that confusion is present in 5.1%, 12.7%, and 18.6%, respectively.9 The absence of fever in older adults is shown in studies where fever, defined as greater than or equal to 37.5°C, is absent in 32% of the very old10and in 40% of patients 65 years or older when it was defined as greater than 37°C.8 The inconsistencies regarding typical symptoms of pneumonia in the older adult population are also confirmed in nursing home residents.11 Ultimately, it is important to remember that any infection in older adults, especially in those residing in long-term care facilities, may present with subtle findings such as an acute change in cognitive and functional status.12
