Lungs and Infectious Disease

 Adventitious Lung Sounds (Extra Sounds, Abnormal Sounds)
Normal: First listen to normal lungs (stethoscope recording).
Crackles: These are high pitched, discontinuous sounds similar to the sound produced by rubbing your hair between your fingers. (Also known as Rales)
Wheezes: These are generally high pitched and "musical" in quality. Stridor is an inspiratory wheeze associated with upper airway obstruction (croup).
Rhonchi: These often have a "snoring" or "gurgling" quality. Any extra sound that is not a crackle or a wheeze is probably a rhonchi.
Whooping Cough: An "inspiratory gasp" is heard, as a patient infected with Bordetella pertussis struggles for air.


Normal lungs

Normal lung radiographs show the vascular markings of vertically oriented
pulmonary artery segments and horizontally directed pulmonary veins (toward
the left atrium). Size of the vessels should gradually decrease as they branch peripherally.

Smaller bronchials are seen as thin walled darker circles. Edematous
thickening of these bronchial walls is one of the earliest findings of congestive failure.

The progressive branching pattern of the hilum is expected from the pulmonary
arteries. Other normal hilar findings include a concave right ventricular outflow
tract segment, and absence of any densities that might represent adenopathy. Enlarged hila should be observed to include rapid tapering in cases of pulmonary
hypertension or localized truncation of part of the pulmonary artery segment (as
can occur with some larger pulmonary emboli).

Haemophilus influenzae Infection

Haemophilus influenzae interstitial pneumonia.
Note patchy infiltrates and thickened interstitial
markings throughout. The radiograph is non-specific
and many causes need to be considered.

Staphylococcus aureus or
Streptococcus pneumoniae Infection

Contrast with these chest X-ray films showing lobar pneumonia.
This is right, upper lobe consolidation characteristic
of infection caused by Staphylococcus aureus or
Streptococcus pneumoniae.

This is also the radiograph typical for Legionella pneumophila infection.

Click the Following Link for a Case Presentation of Pneumonia in the Elderly
http://web.indstate.edu/thcme/micro/bugs/pneumon.htm#Abstract
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Pneumothorax

This pneumothorax radiograph shows marked density differences between the left
and right thoracic cavities. The complete translucency on the left with absence of
vascular markings is characteristic of a pneumothorax. The pressure in the pleural
space is normally 5 cm of water below atmospheric. If air is introduced into the
pleural space and the visceral and parietal layers of the pleura allowed to separate,
the lungs will begin to collapse and the thoracic cage will enlarge.

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