Flail Chest

DEFINITION
A result of chest trauma, where one segment of the chest does not have bony continuity with the rest of the thoracic cage, leading to paradoxical motion and impaired ventilation.
Three or more consecutive ribs in two locations
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EPIDEMIOLOGY
Thoracic trauma.

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AETIOLOGY
Trauma
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BIOLOGICAL BEHAVIOUR

Pathophysiology
Flail segment disrupts normal chest movements.
--> paradoxical motion of the chest wall during expiration and inspiration
- although this defect alone does not cause hypoxia.
Hypoxia contributions from:
- major difficulty usually relates to substantial contusion of the underlying lung with significant hypoxia. Also:
- splinting / pain of breathing
- atelectasis
- biomechanical impact of multiple rib #s

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MANIFESTATIONS

Symptoms

Chest pain
Respiratory distress

Signs
Observe
May not be initially apparent due to splinting.
Asymmetrical and uncoordinated chest movement is evident.
Palpate
Abnormal chest expansion.
Crepitus
Auscultate
Decreased BS.
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INVESTIGATIONS
Imaging shows multiple rib #s.
ABG suggests resp failure with hypoxia.
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MANAGEMENT

Principles are pain management and 'pulmonary toilet'

1. Resuscitate
- administer humidified O2
- ventilate
- fluid resuscitation (do not over-resuscitate in the absence of hypoxia, contused lung is sensitive to under and over hydration).

2. Definitive Rx
Chest tube; expand the lung
Ensure oxygenation
Give fluids judiciously
Provide analgesia
- thoracic epidural is optimal but often not given, and too-often delayed past 24h of injury
- intercostal nerve blocks are an alternative.
- PCA alternative but inferior as narcotics and do not act while sleeping / drowsy.
Severe flail / contusions may need at short period of ventilation (prevention of hypoxia is paramount)
- decision can be made from respiratory rate, PaO2, estimated work of breathing.

Operative rib fixation?
Gaining popularity but not yet widely practiced

Indications are:

1. Flail, stable, thoracotomy
--> ie may as well do it as there anyway; associated with shorter ventilation, less ICU and hospital stay

2. Flail, intubated and ventilated but with no pulmonary contusions.
--> ie, flail is assumed to be contributing to dependence on the ventilator

3. Flail, intubated and contusions, but failure to wean after contusion resolves.
--> flail contributing to ventilated state; fixation reduces time ventilated.

4. Flail, not intubated, good ward care but resp decline.

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REFERENCES
ATLS