Topics / Surgery / Trauma / Pneumothorax

Summary A pneumothorax is an accumulation of air inside the pleural space. Sometimes a one way valve-like mechanism occurs, progressively worsening the condition and resulting in tension pneumothorax. Tension pneumothorax is a clinical diagnosis. The types, presentation, investigations and management is described below.

Definition

The accumulation of air inside the pleural space (between the visceral and the parietal pleura).

Basics

Air enters into the pleural space due to injury of the airway or the chest wall. The injury results in the loss of intrathoracic negative pressure, the lungs are no longer kept expanded. The injury may form a one way valve mechanism that allows air to enter into the pleural space, but it prevents it from escaping. As time progresses, this accumulated air increases in volume and it will progressively decrease the volume of the lung. If the disease process continues, the increased air pressure causes compression of the intrathoraxic structures (obstructive shock). There is reduced venous return and reduced cardiac output.

Types

Traumatic pneumothorax
1. Size
  1. Small Pneumothorax ( < 2cm)
  2. Large Pneumothorax ( > 2cm)
  3. It must be said that there are many different ways to measure the size of a pneumothorax. Some sources may suggest the apex-to-cupola distance (in this case use 3cm instead of 2cm), interpleural distance at the level of the hilus of the lung or Collins method (%).

Mechanism of injury
1. Blunt chest trauma
2. Penetrating chest trauma
3. Iatrogenic (during mechanical ventilation, CVP insertion, lung biopsies)

Type
1. Close pneumothorax: The air will enter the pleural space via the airway, usually due to blunt trauma.
2. Open pneumothorax: There is a connection between the environment and the pleural space due to an injury in the chest wall.
Non-Traumatic (Spontaneous Pneumothorax)
1. Primary (The patient has no underlying disease)
  1. This is due to the rupture of subpleural blebs, the risk is higher in certain groups of individuals such as those who are smokers.
2. Secondary (The patient has an underlying disease)
  1. Common causes are rupture of bullae (emphysema) in COPD, Infections (Pulmonary TB, PJP), cystic fibrosis, malignancy

Tension Pneumothorax Either traumatic or non-traumatic pneumothorax may progress into a tension pneumothorax. There are progressively increasing pressures in the intrathoracic space which may lead to an obstructive shock.

Presentation

Asymptomatic
Acute onset of shortness of breath
Ipsilateral pleuritic chest pain, visible injury
Subcutaneous emphysema
Hyperresonant ipsilateral side
Decreased breath sounds on the affected size
If tension pneumothorax (Distended neck veins, Trachea deviates to the opposite side, signs of obstructive shock – tachycardia, hypotension, pulsus paradoxus)

Diagnosis

Tension pneumothorax is a clinical diagnosis, then perform an immediate chest decompression.
Chest X-Ray (preferably Erect PA on inspiration, supine has decreased sensitivity)
1. Usually there is visible ipsilateral visceral pleura line and reduced lung markings with changes in radiolucency. If there is tension pneumothorax you may see ipsilateral flattening of the diaphragm, widening of the intercostal spaces, mediastinal shift to the contralateral side, deviation of the trachea to the contralateral side), deep sulcus sign
Ultrasound (as part of eFAST)
1. Air accumulates between the visceral and the parietal pleura. This means that when an ultrasound probe is placed on the chest well there will be (1) abscence of the pleura sliding since there is now a space filled with air (2) prominent A-lines (horizontal lines) (3)absence of B-lines (vertical lines) (4) barcode sign instead of the seashore sign in the M-mode
CT Chest – especially for the non-traumatic patients, this will provide some information for the cause.

Management

1. Small Pneumothorax

Usually < 2cm in size, measured from the inside of the third rib to the margin of the lung. These patients should be treated without an intercostal drain if the following is true:

The small pneumothorax is unilateral
The patient is not ventilated/intubated
The patient does not require any anesthesia

You will then need to review the patient and repeat a chest X-Ray after around 3-6 hours. If the pneumothorax has not increased in size then the patient may be discharged. This is because a small pneumothorax will resolve by itself, especially in around 10 days. However, if the size of the pneumothorax has increased in size then you should insert an intercostal drain. However, if the patient has a small pneumothorax and is unstable, the patient may benefit from an ICD. The ICD is inserted in the 5^th intercostal space (bounded by the 5^th and 6^th rib, insert the ICD along the superior border of the 6^th rib [the rib below] to avoid the neurovascular structures), along the anterior axillary line (to avoid the long thoracic nerve) on the ipsilateral side.

The Triangle of Safety This refers to an anatomical region which is considerd a safe position for the insertion of an intercostal drain. This triangle formed by the lateral border of the pectoralis major anteriorly, lateral border of the lateral border of the latissimus dorsi posteriorly and the 5th intercostal space inferiorly. The apex is located at the axilla.

2. Large Pneumothorax

Usually, the size is > 2cm in size, this one requires the insertion of an ICD, which is described below.

3. Tension Pneumothorax

This pneumothorax has become so severe that there is increased tension, compressing the other structures inside the chest, especially the mediastinal structures. This is a clinical diagnosis and the patient will present with the following:

Respiratory signs: Severe respiratory distress (Nasal Flaring, tachypnea, use of accessory muscles of respirations, desaturation on room air), trachea deviates to the opposite side. Cyanosis is a late sign. There will be hype-resonance on the side of the tension pneumothorax and decreased air entry on the side of auscultation
Signs of shock: Tachycardia, hypotension

Step-wise Management

ATLS principles: ABCDE
Immediate chest decompression with by performing a needle thoracostomy (Insert a large bore IV cannula into the second intercostal space, midclavicular line OR 4^th-5^th ICS in anterior axillary line.) This is a temporary form of management, the definitive treatment is the insertion of an intercostal drain (ICD) which occurs afterwards. The ICD should be a large bore, adult size around 36 – 40 Fr.
Then, review results and admit the patient
Position the patient in a upright position since this improves respiratory function
Supplemental oxygen to keep saturations of oxygen > 92%
Mobilize as soon as possible
Chest physiotherapy and breathing exercises. You can ask the patient to blow into a glove and you may also consult physiotherapy.
Removed the ICD once the lung has expanded. You should assess this by repeating an chest X-Ray and also correlate it clinically. The ICD drain has an underwater seal which should have stopped bubbling (this is an indication that it may be removed). There are other types of ICDs that do not display this mechanism and will have other indicators.

Depending on the assessment other departments may need to be consulted: Pulmonology, Cardiothoracic surgery, ICU

4. Open Pneumothorax

Apply a partially occlusive dressing over the lesion. You can make this by occluding 3 sides of a 4-sided dressing. This will create a one-way valve mechanism that allows air to escape the chest but it will not allow the air to enter the pleural space.
Insert an ICD (Tube thoracostomy).

References and Further Reading 1. Walter Sisulu University, Surgery Survival Guide by Dr Jeff John.

Published on 28 July 2022

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A quick approach to Pneumothorax