Aspiration



Aspiration


Monica P. Revelo, MD, PhD

Brandon T. Larsen, MD, PhD





Key Facts


Terminology



  • Entry of particulate matter, fluid, or secretions from stomach, esophagus, oral cavity, nasal cavity, or oropharynx into airway below level of true vocal folds


  • Aspiration pneumonia is pathologic consequence of aspiration


Clinical Issues



  • Common in children and infants with feeding and swallowing problems due to neurological diseases or anatomical anomalies


  • Depends on type of material aspirated as well as extent of injury


  • Meconium aspiration is fatal in 5-10% of cases


  • Mortality is high in acute aspiration of gastric contents


  • Types of aspiration syndromes



    • Meconium-contaminated amniotic fluid


    • Fluids contaminated with bacteria


    • Chemical pneumonitis (Mendelson syndrome)


    • Airway obstruction


    • Exogenous lipoid pneumonia


Image Findings



  • Imaging findings depend on type and severity of aspiration


Macroscopic Features



  • Parenchymal consolidation distal to obstructed airway may be seen in any type of aspiration


Microscopic Pathology



  • Histologic features vary with type of aspirate






Plant material image from aspirated food is readily identified in this case of aspiration pneumonia. Note the surrounding suppurative granulomatous inflammatory response with numerous giant cells image.






In exogenous lipoid pneumonia, aspirated oil is engulfed by abundant foamy histiocytes image and even a foamy giant cell image. In this case, a child in respiratory failure aspirated baby oil 2 days before.


TERMINOLOGY



Definitions



  • Entry of particulate matter, fluid, or secretions from stomach, esophagus, oral cavity, nasal cavity, or oropharynx into airway below level of true vocal folds



    • Aspiration pneumonia is pathologic consequence of aspiration


ETIOLOGY/PATHOGENESIS


Implicated Mechanisms



  • Failure of normal airway clearing mechanisms (glottic closure, cough reflex)


  • Type and amount of aspirate determines mechanism of injury



    • Aspirate inoculum (i.e., gastric content) may produce direct toxic effects (chemical pneumonitis)


    • Stimulation of inflammatory process from large inoculum contaminated with bacteria


    • Obstruction of airways due to large amount of aspirate (> 0.3 mL/kg)


  • Epithelial cell and alveolar macrophage injury result in release of chemical mediators



    • Neutrophils are attracted and activated, with subsequent activation of proteases and production of reactive oxygen species


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Common in children and infants with feeding and swallowing problems due to neurological diseases or anatomical anomalies


  • Age



    • Peak incidence of foreign body aspiration: 10-24 months


Presentation



  • Acute manifestations



    • Cough


    • Wheezing


    • Respiratory distress


    • Atelectasis


    • Airway obstruction


  • Long-term manifestations



    • Bronchiectasis


    • Bronchiolitis obliterans


    • Follicular bronchiolitis


    • Recurrent and prolonged respiratory infections


    • Chronic lung disease


Laboratory Tests



  • Bronchoalveolar lavage (BAL)



    • Shows increased cellularity (lymphocytes, eosinophils, macrophages)


    • Lipid-laden macrophages in great numbers


    • Multinucleated giant cells containing lipid droplets


    • Presence of pepsin is indicative of aspiration of gastric contents


  • Videofluoroscopic swallow study


  • Fiberoptic endoscopic evaluation of swallowing



Treatment

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Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Aspiration

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