Pneumothorax Flashcards
What is a pneumothorax?
Occurs when air gains access to, and accumulates in, the pleural space.
What are the risk factors for pneumothorax?
- Cigarette smoking
- Family history of pneumothorax
- Tall and slender body build
- Age <40
- Recent invasive medical procedure
- Chest traume
- COPD
- Acute severe asthma
Briefly describe the pathophysiology of a pneumothorax
Normally, the alveolar pressure is greater than the intrapleural pressure, while the intrapleural pressure is less than atmospheric pressure. Therefore, if a communication develops between an alveolus and the pleural space, or between the atmosphere and the pleural space, gases will follow the pressure gradient and flow into the pleural space. This flow will continue until the pressure gradient no longer exists or the abnormal communication has been sealed. Because the thoracic cavity is normally below its resting volume, and the lung is above its resting volume, the thoracic cavity enlarges and the lung becomes smaller when a pneumothorax develops.
What are the different types of pneumothorax?
- Spontaneous (primary, secondary and recurrent)
- Traumatic
- Tension
Describe the 3 different types of spontaneous pneumothorax (primary, secondary and recurrent)
- Primary pneumothorax: occurs without clinically apparent pulmonary disease
- Secondary pneumothorax: occurs as a complication of an underlying pulmonary disease, including COPD, asthma, and thoracic endometriosis (catamenial pneumothorax).
- Recurrent pneumothorax: a second episode of spontaneous pneumothorax, either ipsilateral
or contralateral.
What is a traumatic pneumothorax?
Results from either penetrating or blunt injury to the chest. These may be the result of accidental or non-accidental injury.
What is a tension pneumothorax?
Occurs when the intrapleural pressure exceeds atmospheric pressure throughout expiration and often during inspiration. It is a medical emergency that requires prompt decompression.
What are the signs of a pneumothorax?
- Ipsilateral reduced breath sounds
- Ipsilater hyper-inflation of the hemithorax with hyper-resonance on percussion
- Hypoxia
What are the symptoms of a pneumothorax?
- Chest pain
- Dyspnoea
What investigations should be ordered for a pneumothorax?
- Chest X-ray
- Blood tests
- Chest ultrasound
- ABG
- CT chest
Why investigate using chest x-ray?
Use erect posterior-anterior (PA) chest x-ray as the first-line investigation in stable patients.
A visible rim between the lung margin and chest wall, or surgical emphysema and absence of lung markings between the lung margin and chest wall.
How does pneumothorax present on CXR?
A chest xray will show an area between the lung tissue and the chest wall where there are no lung markings. There will be a line demarcating the edge of the lung where the lung markings ends and the pneumothorax begins.
How does a tension pneumothorax present on CXR?
A chest xray will show an area between the lung tissue and the chest wall where there are no lung markings. There will be a line demarcating the edge of the lung where the lung markings ends and the pneumothorax begins.
It will also show tracheal deviation away from side of pneumothorax.
Why investigate using blood tests?
Order a full blood count and clotting screen. Correct clotting abnormalities (INR ≥1.5 or platelets ≤50 x 10⁹/L) before inserting a chest drain in patients who are not critically unwell.
Baseline levels.
Why investigate using chest ultrasound?
Increasingly used to detect pneumothorax, especially for patients who are immobilised following trauma, when an erect PA chest x-ray cannot be obtained.
Absence of pleural sliding; the ‘A’ line sign; presence of ‘lung point’ and ‘barcode’ sign.
Briefly describe how to measure the size of a pneumothorax
Measuring the size of the pneumothorax on a chest xray can be done according to the BTS guidelines from 2010. This involves measuring horizontally from the lung edge to the inside of the chest wall at the level of the hilum.
Where is a chest drain inserted?
Chest drains are inserted into the “triangle of safety”. This triangle is formed by:
- The 5th intercostal space (or the inferior nipple line)
- The mid axillary line (or the lateral edge of the latissimus dorsi)
- The anterior axillary line (or the lateral edge of the pectoris major)
The needle is inserted just above the rib to avoid the neurovascular bundle that runs just below the rib. Once the chest drain is inserted obtain a chest xray to check the positioning.
Briefly describe the pathophysiology of tension pneumothorax
Tension pneumothorax is caused by trauma to chest wall that creates a one-way valve that lets air in but not out of the pleural space. The one-way valve means that during inspiration air is drawn into the pleural space and during expiration, the air is trapped in the pleural space. Therefore more air keeps getting drawn into the pleural space with each breath and cannot escape.
This is dangerous as it creates pressure inside the thorax that will push the mediastinum across, kink the big vessels in the mediastinum and cause cardiorespiratory arrest.
What is the management of a tension pneumothorax?
Insert a large bore cannula into the second intercostal space in the midclavicular line.
If a tension pneumothorax is suspected do not wait for any investigations. Once the pressure is relieved with a cannula then a chest drain is required for definitive management.
