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==Historical Perspective== | ==Historical Perspective== | ||
The literature on aspiration pneumonia came into knowledge of medical society along with the discovery of [[pneumonia]]. During 1893, Veillon was first to write about the role of [[Anaerobic organism|anaerobic bacteria]] in aspiration pneumonia. The major breakthrough came when [[X-rays|x-ray]] was invented by Roentgen in 1896. | |||
==Classification== | ==Classification== | ||
Aspiration pneumonia is a part of aspiration syndrome which is consist of four classes depending on nature of aspirated substance. | Aspiration pneumonia is a part of aspiration syndrome which is consist of four classes depending on nature of aspirated substance including [[Foreign body in respiratory tract|foreign body]] aspiration, [[chemical pneumonitis]], [[Infection|bacterial infection]], and [[lipid pneumonia]]. Aspiration pneumonia depends on the duration of systems might be classified into two groups of acute and chronic. | ||
==Pathophysiology== | ==Pathophysiology== | ||
The mechanism behind damage | Aspiration pneumonia is a common [[pneumonia]] among patients with risk factors including [[neurologic diseases]]. Microaspiration and macroaspiration of different materials are the main cause of aspiration pneumonia. The mechanism behind damage of [[lung]] due to aspiration of depends on the content of aspirate and the response of [[lung]] tissue to the content. Host factors including [[mucociliary clearance]], [[cough reflex]], and [[immune system]] might be probably impaired. [[Chemical pneumonitis]] usually occurs following aspiration of materials that are toxic to [[pulmonary]] tissue. There might be no [[Bacteria|bacterial]] or [[Virus|viral]] organisms involved. It is mostly associated with aspiration of [[gastric acid]]. In case of [[Pharynx|oropharyngeal]] secretions the damage is due to [[bacteria]] infecting and inducing [[inflammation]] in [[lung]] tissues. [[Foreign body]] aspiration might present acutely with mechanical [[obstruction]] or [[chemical pneumonitis]]. [[Lipid pneumonia|Lipoid pneumonia]] is caused by aspiration of mineral [[oil]] when used for [[constipation]] treatment. Following [[oil]] aspiration there is an [[Inflammation|inflammatory]] response with regional [[edema]] and acute [[cough]], [[fever]], and [[dyspnea]]. Patients with [[Genetics|genetic]] syndromes and [[paralysis]] of lower [[cranial nerves]] might be prone to aspiration pneumonia. On [[gross pathology]], different aspirated particles might be seen. On microscopic histopathological analysis, aspirated material fragments, [[inflammation]], [[fibrosis]], and [[skeletal muscle]] fibers might be seen. | ||
==Causes== | ==Causes== | ||
Aspiration pneumonia is caused | Aspiration pneumonia is caused by [[aspiration]] of different particles including [[Secretion|secretions]], [[Stomach|gastric]] contents or any foreign material which reaches lung [[parenchyma]] and damages [[lung]] tissue by [[inflammation]]. [[Microorganism|Microorganisms]] that are responsible for aspiration pneumonia include ''[[Staphylococcus aureus|S. aureus]], [[Streptococcus pneumoniae|S. pneumoniae]], [[Enteric Bacilli|Enteric bacilli]], [[Hemophilus species]], [[Neisseria|Neisseria species]], [[Moraxella catarrhalis|M. catarrhalis]], [[Pseudomonas aeruginosa|P. aeruginosa]].'' | ||
==Differentiating Xyz from Other Diseases== | ==Differentiating Xyz from Other Diseases== | ||
Aspiration pneumonia must be differentiated from other diseases that cause [[productive cough]], [[fever]], and [[dyspnea]]. | |||
==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
The incidence and prevalence of aspiration pneumonia are underestimated. It is mostly because of similarities between [[Pneumonia|pneumonias]] from different causes and lack of specific marker to distinguish [[Pneumonia|pneumonias]] from each other. The [[incidence]] of aspiration pneumonia is approximately 300,000 to 600,000 individuals annually in the United States. The [[prevalence]] of aspiration pneumonia is approximately 5,000 to 15,000 per 100,000 individuals admitted in the hospital due to [[Community-acquired pneumonia|community acquired pneumonia]]. The [[mortality rate]]<nowiki/>of aspiration pneumonia is approximately 10.6-21%. The [[incidence]] of aspiration pneumonia increases with age; the median age at diagnosis is 70-80 years. Males are more commonly affected by aspiration pneumonia than females. There is no racial predilection to aspiration pneumonia. | |||
==Risk Factors== | ==Risk Factors== | ||
Common risk factors in the development of aspiration pneumonia include [[dysphagia]], [[swallowing]] dysfunction, [[altered mental status]], [[Chronic obstructive pulmonary disease|COPD]], and [[Hospital|hospitalization]]. Less common risk factors in the development of aspiration pneumonia include [[Medication|medications]], [[esophageal motility disorders]], [[Nausea and vomiting|vomiting]], [[Feeding tube|enteral feeding]], [[Pharynx|oropharyngeal]] colonization, male sex, and [[smoking]]. | |||
==Screening== | ==Screening== | ||
There is insufficient evidence to recommend routine screening for aspiration pneumonia. | |||
==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
Aspiration pneumonia occurs following aspiration of different materials and particles. Natural history, complications, and prognosis are different for each category. [[Chemical pneumonitis]] usually develop after [[aspiration]] of [[gastric acid]] and might present acutely within two hours. Rapid clinical recovery or worsening of [[Respiratory failure|respiratory distress]] and [[hypoxemia]] might happen. [[Infection|Bacterial infection]] following aspiration is slower that other [[community-acquired pneumonia]] and might be acute, subacute, or chronic. [[Foreign body]]<nowiki/>aspiration might present acutely with mechanical [[obstruction]] or [[chemical pneumonitis]]. Patients might present acutely with [[inflammation]] and [[cough]], [[fever]], and [[dyspnea]]. However, they might be [[asymptomatic]] and present with an incidental mass on radiographs. Complications of aspiration pneumonia include segmental or [[Pneumonia|lobar pneumonia]], [[bronchopneumonia]], [[bronchiectasis]], [[lung abscess]], [[empyema]], [[respiratory failure]], [[bacteremia]], and [[shock]]. | |||
==Diagnosis== | ==Diagnosis== | ||
===Diagnostic Study of Choice=== | ===Diagnostic Study of Choice=== | ||
Revision as of 20:35, 3 April 2018
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Aspiration pneumonia overview On the Web | |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sunny Kumar MD [2]
Overview
Historical Perspective
The literature on aspiration pneumonia came into knowledge of medical society along with the discovery of pneumonia. During 1893, Veillon was first to write about the role of anaerobic bacteria in aspiration pneumonia. The major breakthrough came when x-ray was invented by Roentgen in 1896.
Classification
Aspiration pneumonia is a part of aspiration syndrome which is consist of four classes depending on nature of aspirated substance including foreign body aspiration, chemical pneumonitis, bacterial infection, and lipid pneumonia. Aspiration pneumonia depends on the duration of systems might be classified into two groups of acute and chronic.
Pathophysiology
Aspiration pneumonia is a common pneumonia among patients with risk factors including neurologic diseases. Microaspiration and macroaspiration of different materials are the main cause of aspiration pneumonia. The mechanism behind damage of lung due to aspiration of depends on the content of aspirate and the response of lung tissue to the content. Host factors including mucociliary clearance, cough reflex, and immune system might be probably impaired. Chemical pneumonitis usually occurs following aspiration of materials that are toxic to pulmonary tissue. There might be no bacterial or viral organisms involved. It is mostly associated with aspiration of gastric acid. In case of oropharyngeal secretions the damage is due to bacteria infecting and inducing inflammation in lung tissues. Foreign body aspiration might present acutely with mechanical obstruction or chemical pneumonitis. Lipoid pneumonia is caused by aspiration of mineral oil when used for constipation treatment. Following oil aspiration there is an inflammatory response with regional edema and acute cough, fever, and dyspnea. Patients with genetic syndromes and paralysis of lower cranial nerves might be prone to aspiration pneumonia. On gross pathology, different aspirated particles might be seen. On microscopic histopathological analysis, aspirated material fragments, inflammation, fibrosis, and skeletal muscle fibers might be seen.
Causes
Aspiration pneumonia is caused by aspiration of different particles including secretions, gastric contents or any foreign material which reaches lung parenchyma and damages lung tissue by inflammation. Microorganisms that are responsible for aspiration pneumonia include S. aureus, S. pneumoniae, Enteric bacilli, Hemophilus species, Neisseria species, M. catarrhalis, P. aeruginosa.
Differentiating Xyz from Other Diseases
Aspiration pneumonia must be differentiated from other diseases that cause productive cough, fever, and dyspnea.
Epidemiology and Demographics
The incidence and prevalence of aspiration pneumonia are underestimated. It is mostly because of similarities between pneumonias from different causes and lack of specific marker to distinguish pneumonias from each other. The incidence of aspiration pneumonia is approximately 300,000 to 600,000 individuals annually in the United States. The prevalence of aspiration pneumonia is approximately 5,000 to 15,000 per 100,000 individuals admitted in the hospital due to community acquired pneumonia. The mortality rateof aspiration pneumonia is approximately 10.6-21%. The incidence of aspiration pneumonia increases with age; the median age at diagnosis is 70-80 years. Males are more commonly affected by aspiration pneumonia than females. There is no racial predilection to aspiration pneumonia.
Risk Factors
Common risk factors in the development of aspiration pneumonia include dysphagia, swallowing dysfunction, altered mental status, COPD, and hospitalization. Less common risk factors in the development of aspiration pneumonia include medications, esophageal motility disorders, vomiting, enteral feeding, oropharyngeal colonization, male sex, and smoking.
Screening
There is insufficient evidence to recommend routine screening for aspiration pneumonia.
Natural History, Complications, and Prognosis
Aspiration pneumonia occurs following aspiration of different materials and particles. Natural history, complications, and prognosis are different for each category. Chemical pneumonitis usually develop after aspiration of gastric acid and might present acutely within two hours. Rapid clinical recovery or worsening of respiratory distress and hypoxemia might happen. Bacterial infection following aspiration is slower that other community-acquired pneumonia and might be acute, subacute, or chronic. Foreign bodyaspiration might present acutely with mechanical obstruction or chemical pneumonitis. Patients might present acutely with inflammation and cough, fever, and dyspnea. However, they might be asymptomatic and present with an incidental mass on radiographs. Complications of aspiration pneumonia include segmental or lobar pneumonia, bronchopneumonia, bronchiectasis, lung abscess, empyema, respiratory failure, bacteremia, and shock.