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Pneumothorax
Pathophysiology: Any process allowing atmospheric air to
enter the potential pleural space leads to reduction of negative
intrapleural pressure and varying degrees of lung collapse. The
dreaded complication is a tension pneumothorax. In this
case, the air enters the pleural space and a flap valve-like
effect occurs with less air leaving the pleural space on
expiration than entering on inspiration. As a result, the
pleural space progressively inflates, deviating the mediastinum,
increasing lung compliance and compressing the great veins.
Commonest causes:
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Spontaneous:
typically in young tall athletic patients, often recurrent
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Associated with
many interstitial lung diseases and infections (eg. PCP,
interstitial fibrosis)
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Trauma: fractured
ribs; stab and bullet wounds
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Iatrogenic
following needle biopsy, central line insertion or
thoracentesis
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Rupture of
peripheral blebs and bullae especially in patients with
bullous emphysema
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Infections, usually
granulomatous lung disease (eg. tuberculosis)
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Rarely, with tumor
destruction of airways
CXR Findings:
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Classic sign: Visceral
pleural sign: the line of the visceral pleura is seen
outlining the collapsed lung
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No airways or
vessels beyond visceral pleura of collapsed lung
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May be dynamic
movement of mediastinum on inspiration and expiration (usually
not useful except if one does fluoroscopy)
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Tension
pneumothorax: mediastinum shifted contralaterally
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Superior Sulcus
sign: typical features of pneumothorax seen in upright
patient. In the supine patient, air rises to
anterior and inferior position, giving a circular area of
lucency in the costophrenic sulcus area.
Clues:
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Tension
pneumothorax is a medical emergency and needs rapid treatment
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Bright light all
plain films to look for subtle visceral pleural lines
especially in the lung apices
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Communicate
findings to the referring MD
“Aunt Sophies”:
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Tissue folds
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Rib surfaces may
mimic visceral pleural sign
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Blebs, bullae and
cavities
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Severe
emphysematous lung disease
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Technical factors
with hyperlucency in a lung (eg. rotation)
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