Pneumothorax (simple)

DEFINITION
Air entering the potential space between lung and chest wall, compromising ventilation.
See also tension pneumothorax and open pneumothorax.

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INCIDENCE
Common

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AETIOLOGY
Spontaneous or traumatic

Primary
- absence of underlying lung disease
- typically young males

Secondary
- underlying lung disease
- typically older patients

Traumatic
- both penetrating and non-penetrating thoracic injuries.
- lung injury with air leak most commonly.
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BIOLOGICAL BEHAVIOUR

Pathophysiology

Normally visceral and parietal pleura are closely opposed.
Air in the pleural space collapses the lung tissue.
Ventilation/perfusion mismatch follows.

Complications
Tension pneumothorax
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MANIFESTATIONS
Symptoms
Local
Spontaneous
Sharp unilateral chest pain
- worse on deep breathing
- can be worse with posture change
Shortness of breath
- minimal SOB in 2/3 of pts.

Signs
Percuss
Hyper-resonance
Auscultate
Decreased breath sounds
Crepitus possible
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INVESTIGATIONS

Imaging

CXR
- convex lung edge
- surrounding lucent zone
- inspiratory and expiratory films are equal in sensitivity

CT
- good for small / occult pneumothorax

USS
- matches sensitivity and specificity of other techniques in the right hands
- loss of lung sliding
- absence of comet-tail artifacts
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MANAGEMENT

(Traumatic)

Observation
Appropriate for:
- asymptomatic pts with <20% pneumo
Supplemental O2 increases resolution
Repeat CXR in 6h
OR if becomes symptomatic

Pigtail Drainage
8-12Fr catheter
Not as reliable as conventional thoracostomy in trauma; not widely practiced but probably safe if selectively applied.
(Also Flutter Valves - effective in 85%)

Tube Thoracostomy
Chest drain insertion.
- get a CXR after insertion.
Size 36 appropriate if associated haemothorax
Cover with prophylactic antibiotics (evidence equivocal)

Removal considered when pneumo resolved, minimal tube drainage of 75-100ml

Surgical Interventions
Occasionally considered:
- for non-traumatic recurrent pneumo
- or if fails to resolve with persistent air leak at 4d
- indications also can include bilateral pneumo, HIV pts, and high-risk professions.
Minimally invasive approaches preferred.
- mechanical pleurodesis usual; abrading pleural surfaces.
- nonoperative / talc more painful with greater recurrence.
Single trochar, sixth intercostal space, ipsilateral lung collapsed.
Two additional ports, triangulated.
Abrade, saline injection to reveal parenchymal leaks; chest drain, reexpansion.

Pitfalls
Do not undertake intubation or PPV prior to insertion of chest tube or else risk tension.
 
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