A 75-year-old man is brought to the office due to 2 days of confusion and poor food consumption. The patient has a history of Alzheimer dementia with behavioral symptoms, hypertension, and left lobe hepatic resection due to traumatic injury during a fall 2 years ago. His medications include lisinopril, amlodipine, quetiapine, and donepezil. He has never smoked cigarettes. He lives at home with his wife and is usually ambulatory. Temperature is 38.8 C (101.8 F), blood pressure is 128/78 mm Hg, pulse is 106/min, and respirations are 18/min. BMI is 24 kg/m2. His height is 193 cm (6 ft 4 in). The patient appears ill and is oriented to person only. The neck is supple. There is increased tactile fremitus and dullness to percussion at the right lung base. Pulmonary auscultation reveals crackles over the lower right lung field. The rest of the examination is normal. Which of the following is the greatest risk factor for this patient's current condition?
Risk factors for community-acquired pneumonia | |
Impaired immunity |
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Impaired pulmonary function |
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Increased microaspiration |
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Medications |
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This patient's acute confusion, fever, tachycardia, and signs of right lower lung consolidation (eg, tactile fremitus, dullness to percussion, crackles) suggest community-acquired pneumonia (CAP).
Risk of CAP is increased in elderly patients due to age-related impairments in innate and specific immunity. In addition, the use of atypical antipsychotic medications (eg, quetiapine) in elderly patients is associated with a much higher risk of CAP. Although the mechanism is unclear, it may be related to cholinergic and histamine receptor-1 inhibition, which causes oropharyngeal dryness, reduced ability to generate a food bolus, and an increased risk of subsequent aspiration.
An additional risk factor in this patient is the presence of dementia (eg, Alzheimer), which increases the risk of aspiration due to impaired ability to protect the airway and coordinate the muscles involved in swallowing.
(Choice A) A tall, thin body habitus increases the risk of spontaneous pneumothorax due to stretching of the apical regions of the lungs. However, body habitus is not strongly associated with an increased risk of CAP.
(Choice B) Remote hepatic resection should not influence the risk of CAP. Recent hepatic surgery (eg, days ago) could potentially cause pneumonia due to hematogenous dissemination from a hepatic abscess.
(Choice C) Patients taking ACE inhibitors (eg, lisinopril) may be somewhat protected against CAP; these drugs do not increase the risk of the disorder.
Educational objective:
Atypical antipsychotic medications (eg, quetiapine) increase the risk of CAP in elderly patients. Although the exact mechanism is unclear, it may be due to anticholinergic and antihistamine effects of the drug, which reduce the ability to form a food bolus and increase the risk of aspiration.