An 80-year-old nursing home resident is brought to the ED af…
An 80-year-old nursing home resident is brought to the ED after two days of worsening confusion and decreased mobility. Vitals: T 37.2°C, HR 92, BP 118/60, SpO₂ 91% on room air. He denies cough or dysuria, and physical exam is nonspecific. Labs show WBC 9.8, creatinine 1.6 (baseline 1.0). Chest X-ray reveals right lower lobe infiltrate. Which of the following best explains this clinical presentation?