Aspiration pneumonia
Classification and external resources
Histopathologic image of aspiration pneumonia in an elderly patient with debilitating neurologic illness. Note foreign-body giant cell reaction. Autopsy case. H & E stain.
ICD-10	J69.0, P24.9
ICD-9	507, 770.12, 770.14, 770.16, 770.18
MedlinePlus	000121
eMedicine	emerg/464
MeSH	D011015

Aspiration pneumonia is bronchopneumonia that develops due to the entrance of foreign materials that enter the bronchial tree,^[1] usually oral or gastric contents (including food, saliva, or nasal secretions). Depending on the acidity of the aspirate, a chemical pneumonitis can develop, and bacterial pathogens (particularly anaerobic bacteria) may add to the inflammation.

Contents 1 Causes 1.1 Implicated bacteria 2 Location 3 Diagnosis 4 See also 5 References

[edit] Causes

Aspiration pneumonia is often caused by an incompetent swallowing mechanism, such as occurs in some forms of neurological disease (a common cause being strokes) or while a person is intoxicated. An iatrogenic cause is during general anaesthesia for an operation and patients are therefore instructed to be nil per os (NPO) (aka Nothing By Mouth) for at least four hours before surgery.

Whether aspiration pneumonia represents a true bacterial infection or a chemical inflammatory process remains the subject of significant controversy. Both causes may present with similar symptoms.

[edit] Implicated bacteria

When bacteria are implicated, they are usually of the anaerobic oral flora:

• Bacteroides^[2]
• Prevotella^[2]
• Fusobacterium^[2]
• Peptostreptococcus^[2]

They may also be admixed with aerobic bacteria:

• Streptococcus pneumoniae^[2]
• Staphylococcus aureus^[2]
• Haemophilus influenzae^[2]
• Pseudomonas aeruginosa^[2]

[edit] Location

Pneumonia
Infectious pneumonias
Bacterial pneumonia Viral pneumonia Fungal pneumonia Parasitic pneumonia Atypical pneumonia Community-acquired pneumonia Healthcare-associated pneumonia Hospital-acquired pneumonia Ventilator-associated pneumonia Severe acute respiratory syndrome
Pneumonias caused by infectious or noninfectious agents
Aspiration pneumonia Lipid pneumonia Eosinophilic pneumonia Bronchiolitis obliterans organizing pneumonia
Noninfectious pneumonia
Chemical pneumonia
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The location is often gravity dependent, and depends on the patient position. Generally the right middle and lower lung lobes are the most common sites of infiltrate formation due to the larger caliber and more vertical orientation of the right mainstem bronchus. Patients who aspirate while standing can have bilateral lower lung lobe infiltrates. The right upper lobe is a common area of consolidation in alcoholics who aspirate in the prone position.^[3]

[edit] Diagnosis

Aspiration pneumonia is typically diagnosed by a combination of clinical circumstances (debilitated or neurologically impaired patient), radiologic findings (right lower lobe pneumonia) and microbiologic cultures. Some cases of aspiration pneumonia are caused by aspiration of food particles or other particulate substances like pill fragments; these can be diagnosed by pathologists on lung biopsy specimens ^[4].

[edit] See also

• Dysphagia
• Meconium aspiration syndrome
• Nosocomial pneumonia
• Superior mesenteric artery syndrome

[edit] References

v • d • e Pathology of respiratory system (J, 460-519), respiratory diseases Upper RT (including URTIs, Common cold) Head sinuses: Sinusitis nose: Rhinitis (Vasomotor rhinitis, Atrophic rhinitis, Hay fever) · Nasal polyp · Rhinorrhea · nasal septum (Nasal septum deviation, Nasal septum perforation, Nasal septal hematoma) tonsil: Tonsillitis · Adenoid hypertrophy · Peritonsillar abscess Neck pharynx: Pharyngitis (Strep throat) larynx: Laryngitis · Croup · Laryngospasm · vocal folds: Vocal fold nodule · epiglottis: Epiglottitis trachea: Tracheitis · Tracheal stenosis Retropharyngeal abscess Lower RT/lung disease (including LRTIs) Bronchial/ obstructive acute: Acute bronchitis chronic: COPD (Chronic bronchitis, Emphysema, Diffuse panbronchiolitis) · Asthma (Status asthmaticus) · Bronchiectasis unspecified: Bronchitis · Bronchiolitis (Bronchiolitis obliterans) Interstitial/ restrictive External agents/ occupational lung disease Pneumoconiosis (Asbestosis, Baritosis, Bauxite fibrosis, Berylliosis, Caplan's syndrome, Chalicosis, Coalworker's pneumoconiosis, Siderosis, Silicosis, Byssinosis) Hypersensitivity pneumonitis (Bagassosis, Bird fancier's lung, Farmer's lung) Other ARDS · Pulmonary edema · Löffler's syndrome/Eosinophilic pneumonia · Respiratory hypersensitivity (Allergic bronchopulmonary aspergillosis) Hamman-Rich syndrome · Idiopathic pulmonary fibrosis · Sarcoidosis Obstructive or restrictive Pneumonia/ pneumonitis By pathogen Viral · Bacterial (Pneumococcal, Klebsiella) / Atypical bacterial (Mycoplasma, Legionnaires' disease, Chlamydiae) · Fungal (Pneumocystis) · Parasitic · noninfectious (Chemical/Mendelson's syndrome, Aspiration/Lipid) By vector/route Community-acquired · Healthcare-associated · Hospital-acquired By distribution Broncho- · Lobar IIP UIP · DIP · BOOP-COP · NSIP · RB Other Atelectasis · circulatory (Pulmonary hypertension, Pulmonary embolism) · Lung abscess Pleural cavity/ mediastinum Pleural disease Pleuritis/pleurisy Pneumothorax/Hemopneumothorax (Tension pneumothorax) Pleural effusion: Hemothorax · Hydrothorax · Chylothorax · Empyema/pyothorax · Malignant Fibrothorax Mediastinal disease Mediastinitis · Mediastinal emphysema Other/general Respiratory failure · Influenza · SARS · Idiopathic pulmonary haemosiderosis · Pulmonary alveolar proteinosis respiratory system navs: anat nose,larynx/lower+thoracic cavity/physio/dev, noncongen/congen/tumors, symptoms+signs/eponymous, proc

v • d • e Certain conditions originating in the perinatal period / fetal disease (P, 760-779) Maternal factors and complications placenta (Placenta praevia, Placental insufficiency) · Chorion/Amnion/Umbilical cord Chorioamnionitis  · Umbilical cord prolapse · Nuchal cord  · Twin-to-twin transfusion syndrome Length of gestation and fetal growth Small for gestational age · Large for gestational age · Preterm birth · Postmature birth Birth trauma Cephalhematoma · Brachial plexus lesion (Erb's palsy, Klumpke paralysis) By system Respiratory Intrauterine hypoxia · Infant respiratory distress syndrome · Transient tachypnea of the newborn · Meconium aspiration syndrome · pleural disease (Pneumothorax, Pneumomediastinum) · Wilson-Mikity syndrome · Bronchopulmonary dysplasia Cardiovascular Pneumopericardium · Persistent fetal circulation Haemorrhagic and haematological/ hematologic disease Vitamin K deficiency (Haemorrhagic disease of the newborn) · Hemolytic disease of the newborn (ABO HDN • Anti-Kell HDN • Rhesus c HDN • Rhesus D HDN • Rhesus E HDN) · Rh disease · Hydrops fetalis · Hyperbilirubinemia (Kernicterus, Neonatal jaundice) Velamentous cord insertion Digestive system Ileus · Necrotizing enterocolitis · Meconium peritonitis Integument and temperature regulation Erythema toxicum Nervous system Periventricular leukomalacia Musculoskeletal system Gray baby syndrome · muscle tone (Congenital hypertonia, Congenital hypotonia) Other disorders Perinatal infection (Congenital rubella syndrome, Neonatal herpes simplex) · Omphalitis Stillbirth/Perinatal mortality obstetric navs: pregnancy, conditions of mother/conditions of fetus, eponymous signs, proc