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Pneumonia: Difference between revisions

Pneumonia (view source)

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'''Pneumonia''' is an acute inflammation of the lung parenchyme, with involvement of the bronchioli and alveoli, most often caused by microbes. It can have significant mortality. It’s a very common condition. In young people, it usually have a mild natural course, but for elderly, it has a high mortality.
<section begin="radiology" />'''Pneumonia''' is an acute inflammation of the lung parenchyme, with involvement of the bronchioli and alveoli, most often caused by microbes. It can have significant mortality. It’s a very common condition. In young people, it usually have a mild natural course, but for elderly, it has a high mortality.<section end="radiology" />


'''Community-acquired pneumonia''' affects 0,1 – 1% of the adult population each year. It’s more common in young children and older adults, especially those with comorbidities. It’s more common in the winter months. The mortality is higher in the elderly than children.
'''Community-acquired pneumonia''' affects 0,1 – 1% of the adult population each year. It’s more common in young children and older adults, especially those with comorbidities. It’s more common in the winter months. The mortality is higher in the elderly than children.


'''Hospital-acquired pneumonia''' can affect anyone who is admitted to the hospital. It’s a severe condition which causes significant mortality.
'''Hospital-acquired pneumonia''' can affect anyone who is admitted to the hospital. It’s a severe condition which causes significant mortality.
 
<section begin="radiology" />
== Classification ==
== Classification ==<section end="radiology" />
According to the place where the patient acquired the infection:
According to the place where the patient acquired the infection:


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This classification is important because the causative agents and therefore the management are different for each type.
This classification is important because the causative agents and therefore the management are different for each type.
 
<section begin="radiology" />
According to the pathological distribution:
According to the pathological distribution:


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* Aspiration pneumonia
* Aspiration pneumonia
** Anaerob bacteria
** Anaerob bacteria
 
<section end="radiology" />
Risk factors
Risk factors


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In atypical pneumonia, the symptoms are usually non-specific like nausea, muscle aches, etc., rather than pulmonary. Atypical pneumonia can cause less severe pulmonary symptoms, as well as extrapulmonary symptoms like diarrhoea, hepatosplenomegaly, etc.
In atypical pneumonia, the symptoms are usually non-specific like nausea, muscle aches, etc., rather than pulmonary. Atypical pneumonia can cause less severe pulmonary symptoms, as well as extrapulmonary symptoms like diarrhoea, hepatosplenomegaly, etc.
 
<section begin="radiology" />
== Diagnosis ==
== Diagnosis ==
In CAP, imaging and microbiology are not necessary, and the condition is rather diagnosed based on clinical features. In nosocomial pneumonia, imaging and microbiology is important judge the severity and to target the treatment.
In CAP, imaging and microbiology are not necessary, and the condition is rather diagnosed based on clinical features. In nosocomial pneumonia, imaging and microbiology is important judge the severity and to target the treatment.
 
<section end="radiology" />
=== Physical exam ===
=== Physical exam ===


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There are rapid antigen tests of urine for detection of S. pneumoniae and legionella, which can be used for more complicated cases. This is usually not necessary in a typical case of CAP. Atypical bacteria can’t be cultured but the specific pathogen can be determined by serology or PCR.
There are rapid antigen tests of urine for detection of S. pneumoniae and legionella, which can be used for more complicated cases. This is usually not necessary in a typical case of CAP. Atypical bacteria can’t be cultured but the specific pathogen can be determined by serology or PCR.
 
<section begin="radiology" />
=== Imaging ===
=== Imaging ===
The gold standard for diagnosis is the presence of a new opacity on [[chest x-ray]] in the setting of typical clinical features. The opacity is caused by the consolidation of the tissue, caused by presence of exudate in the alveoli. Chest x-ray is negative in the first 24 – 48 hours. The sensitivity of chest x-ray for pneumonia is low, and so a negative x-ray does not rule it out, especially in the early phases.The chest x-ray findings usually persist for weeks even after symptoms have cleared, so they’re usually not used for follow-up for pneumonia. CT may also visualise pneumonia but is unnecessary for uncomplicated cases.
The gold standard for diagnosis is the presence of a new opacity on [[chest x-ray]] in the setting of typical clinical features. The opacity is caused by the consolidation of the tissue, caused by presence of exudate in the alveoli. Chest x-ray is negative in the first 24 – 48 hours. The sensitivity of chest x-ray for pneumonia is low, and so a negative x-ray does not rule it out, especially in the early phases.The chest x-ray findings usually persist for weeks even after symptoms have cleared, so they’re usually not used for follow-up for pneumonia. CT may also visualise pneumonia but is unnecessary for uncomplicated cases.
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If a consolidation has been found on chest radiograph and a diagnosis of pneumonia has been made, a repeat radiograph should be made after resolution of the pneumonia to rule out [[lung cancer]].
If a consolidation has been found on chest radiograph and a diagnosis of pneumonia has been made, a repeat radiograph should be made after resolution of the pneumonia to rule out [[lung cancer]].
 
<section end="radiology" />
=== Differential diagnosis ===
=== Differential diagnosis ===
* [[Acute bronchitis]]
* [[Acute bronchitis]]