Aspiration Risk

Aspiration Risk

Journal not recorded · Published 2026 01

Ryan N. Hoecker, John Schweiger, Joseph Prunier, Anterpreet Dua

Read the original publication

A plain-language reading has not been prepared for this paper yet.

Original abstract

Aspiration is the unintentional passage of material from the oropharynx or gastrointestinal tract into the larynx, tracheobronchial tree, or lung parenchyma. Aspirated material may include saliva, oral secretions, food, liquids, gastric contents, bile, blood, or foreign material. Although small-volume aspiration may occur without clinically apparent disease, aspiration can cause airway obstruction, chemical pneumonitis, bacterial pneumonia, acute hypoxemic respiratory failure, acute respiratory distress syndrome, lung abscess, empyema, bronchiectasis, or chronic aspiration-related lung disease. Normal swallowing requires coordinated oral, pharyngeal, and esophageal phases. During the pharyngeal phase, elevation of the larynx, epiglottic inversion, vocal-fold closure, pharyngeal contraction, and an effective cough reflex help prevent material from entering the lower respiratory tract. Dysfunction at any stage may impair airway protection. Aspiration risk is therefore increased in patients with oropharyngeal dysphagia, neurologic disease, impaired consciousness, sedative exposure, neuromuscular weakness, structural head and neck disease, esophageal dysmotility, gastroesophageal reflux, vomiting, or delayed gastric emptying. Aspiration syndromes are classified according to aspirate composition, volume, bacterial burden, site of deposition, and temporal pattern. Macroaspiration refers to the inhalation of a clinically significant volume of material and may cause abrupt airway obstruction or acute lung injury. Microaspiration is often recurrent and clinically silent but may contribute to aspiration pneumonia or chronic airway injury in susceptible patients. Aspiration pneumonitis is an acute inflammatory lung injury caused by inhalation of noxious material, most often acidic gastric contents. In contrast, aspiration pneumonia is an infectious process that follows aspiration of colonized oropharyngeal secretions or gastrointestinal contents into the lower respiratory tract. These syndromes may overlap, particularly when partially digested gastric contents contain both acidic material and bacteria. The clinical course ranges from asymptomatic aspiration to rapidly progressive respiratory compromise. Chemical pneumonitis typically develops soon after a witnessed macroaspiration event, whereas aspiration pneumonia may develop more insidiously after unwitnessed or recurrent aspiration. Older adults and patients with frailty, stroke, dementia, Parkinson disease, critical illness, or impaired swallowing are disproportionately affected and may have recurrent events with substantial morbidity and mortality. Aspiration-related lung injury generally follows gravity-dependent bronchopulmonary segments. In patients who aspirate while upright, infiltrates commonly involve the basal lower-lobe segments. In recumbent patients, the posterior upper lobes and superior segments of the lower lobes are more often affected. The right lung is frequently involved because of the more vertical course of the right main bronchus, although bilateral or nondependent disease may occur depending on body position, aspirate volume, and underlying lung disease. Recognition of aspiration risk and early differentiation among airway obstruction, aspiration pneumonitis, and aspiration pneumonia are essential, as diagnostic evaluation, airway management, antimicrobial therapy, and preventive interventions should be individualized to the clinical setting and suspected aspirate.