Trauma: pneumothorax Flashcards
Define pneumothorax
Pneumothorax occurs when air gains access to, and accumulates in, the pleural space
Pleural space = potential space between visceral and parietal pleura
What other substances may accumulate in the pleural cavity? How can you differentiate these from a pneumothorax?
Chylothorax = lymph accumulation
Haemothorax = blood accumulation
These will typically show bright white on CXR , where air will show as darker
Risk factors + aeitiology of spontaneous pneumothorax
Caused by ruptured subpleural apical blebs
Risk factors:
- Family history
- Male
- gender
- Young age
- Asthenic body habitus (slim, tall stature) (e.g., in Marfan syndrome)
- Smoking (90% of cases): up to 20-fold increase in risk (risk increases with the cumulative number of cigarettes smoked)
- Homocystinuria
Classify the different types of pneumothorax
1.
-
Spontaneous pneumothorax
- Primary spontaneous pneumothorax: occurs in patients without clinically apparent underlying lung disease
- Secondary spontaneous pneumothorax: occurs as a complication of underlying lung disease
- Recurrent pneumothorax: a second episode of spontaneous pneumothorax
- Traumatic pneumothorax: a type of pneumothorax caused by a trauma (e.g., penetrating injury, iatrogenic trauma)
- Tension pneumothorax: a life-threatening variant of pneumothorax characterized by progressively increasing pressure within the chest and cardiorespiratory compromise
Give examples of medical procedures causing iatrogenic penumothorax
- FNA of lung lesions
- thoracentesis
- endoscopic transbronchial biopsy
- central venous catheter placement
- barotrauma as a result of mechanical ventilation.
Which pre-existing conditions can predispose to spontaneous pneumothorax?
Mostly in COPD patients
- COPD (smoking) → rupture of bullae in emphysema
- Pulmonary tuberculosis
- Cystic fibrosis → bronchiectasis with obstructive emphysema and bleb or cyst rupture
- Pneumocystis pneumonia → alveolitis, rupture of a cavity
- Malignancy
- Catamenial pneumothorax (thoracic endometriosis): extremely rare
- *
How can pneumothorax be classified?
CLOSED
- air enters through a hole in the lung (e.g., following blunt trauma)
OPEN
- Air enters through a lesion in the chest wall (e.g. following penetrating trauma)
- Air enters the pleural space on inspiration and leaks to the exterior on expiration
- Air shifts between the lungs
TENSION
- disrupted visceral/parietal pleura/tracheobronchial tree → air enters the pleural space on inspiration but cannot exit
- any type of pneumothorax can progress to this
3 causes of traumatic pneumothorax
- Blunt trauma (e.g., motor vehicle accident in which the thorax hits the steering wheel or rib fracture occurs)
- Penetrating injury (e.g., gunshot, stab wound)
- Iatrogenic pneumothorax (PEEP, thoracocentesis, CVC placement, biopsy)
Explain the pathogenesis of tension pneumothorax
- Disrupted visceral/ parietal pleura or tracheobronchial tree
- → air enters the pleural space on inspiration but cannot exit
- → progressive accumulation of air in the pleural space and increasing positive pressure within the chest
- → collapse of ipsilateral lung and compression of contralateral lung, trachea, heart, and SVC
- → impaired respiratory function, reduced venous return to the heart and CO
- → hypoxia and hemodynamic instability
What are the presenting signs and symptoms of moderate-mild pneumothorax?
Sudden, severe, and/or stabbing, ipsilateral pleuritic chest
pain and dyspnea
- reduced/absent breath sounds
- hyperresonant on percussion w ipsilateral hyperinflation of the hemithorax
- decreased fremitus on the ipsilateral side
- Subcutaneous emphysema
What are the additional findings of tension pneumothorax?
- Cardiopulmonary deterioration:
- Hypotension; this suggests imminent cardiac arrest
- Respiratory distress
- Low SaO2
- Tachycardia
- Shock
- Loss of consciousness.
- Congested neck veins
- Pulsus paradoxicus
- Tracheal deviation to contralateral side
- Sweating
- Skin emphysema
- Ipsilateral reduced breath sounds- most common finding, also found in non-tension
How is pneumothorax usually diagnosed?
CXR
Erect postero-anterior (PA) x-ray in inspiration
In cases of suspected tension pneumothorax, immediate decompression is a priority and should not be delayed by imaging.
What are some classic findings of pneumothorax on CXR?
- Ipsilateral pleural line with reduced/absent lung markings
- Abrupt change in radiolucency
- Deep sulcus sign- decreased radiodensity and deepened costophrenic angle on ipsilateral side due to collection of interpleural air
- Hemidiaphragm elevation on the ipsilateral side
- Mediastinal + tracheal shift towards contralateral side
What other investigations would you do for pneumothorax?
Bedside
- ABG
- FBC, clotting screens
-
Chest USS- esp. if immobilised following trauma
- Absence of pleural sliding
- Absence of B-lines
- Barcode sign instead of seashore sign in M-mode
- Combination of prominent A-lines and absent B-lines
CT chest
- if uncertainty about diagnosis
- guides best place to insert chest drain
- detailed assessment of bullae
How is a non-tension pneumothorax managed?
Assess patient stability (see stability criteria for spontaneous pneumothorax)
Provide respiratory support and treat dyspnea
Evaluate the type and size of pneumothorax
- Tension pneumothorax, unstable patients, bilateral pneumothorax: immediate chest decompression
- Spontaneous pneumothorax: conservative management or chest tube placement
- Mechanical ventilation necessary: chest tube placement
How is tension/bilateral/unstable pneumothorax managed?
Immediate decompression required- put out 2222
-
emergency needle thoracostomy
- 14-16 large gauge needle into 2nd ICS MCL on affected side, just above the 3rd rib
- should hear a whoosh of air - up to 2.5L
-
chest drain placement
- usually in 4-5th ICS (nipple line)
- connect tubing to water seal or suctioning
- Follow up CXR after the procedure is complete
Describe the triangle of safety
With the arm abducted, the apex is the axilla, and the triangle is formed by the:
- lateral border of the pectoralis major anteriorly
- lateral border of the latissimus dorsi posteriorly
- inferiorly, by a horizontal line from the nipple (commonly the 5th intercostal space)
