Pneumothorax-a short review

 

Definition1

Pneumothorax is accumulation of air within the pleural space leading to passive atelectasis of the lung.

Classification

Pneumothorax is classified into 2 major types

• Spontaneous

• Traumatic.

Spontaneous pneumothorax is of 2 types2

• Primary spontaneous pneumothorax (PSP) which develops without any obvious cause. Unrecognized subpleural bleb may be the cause2.

• Secondary spontaneous pneumothorax develops in diseased lungs and causes are asthma, COPD, lung cavity, lung abscess, and cysts.

Traumatic pneumothorax is of two types

• Accidental: due to penetrating or blunt trauma and air enters the pleural cavity through the chest wall or visceral pleura through alveolar rupture from sudden compression of the chest.

• Iatrogenic: develops during diagnostic or therapeutic interventions. Common situations are endoscopic procedures, insertion of jugular/subclavian vein cannula, transthoracic needle biopsy, and aspiration of pleural fluid.

Clinical types

• Closed: air leak stops as the defect gets closed and will not progress further.

• Open: there is a fistulous communication and air moves to and fro during respiration. This type of pneumothorax does not cause increased intrapleural pressure.

• Tension: This is a medical emergency as air enters the pleural space, but will not escape.   This creates high intrapleural pressure and exerts a pressure effect on the heart and opposite lung. If not interfered immediately, it may lead to cardio-respiratory distress.

Clinical features

• Main symptoms are chest pain and shortness of breath. Chest pain is sharp and sudden in onset Cough and fatigue are other symptoms of pneumothorax.

• Physical signs include tachycardia, tachypnoea and hypotension. There will be reduced expansion and reduced breath sound on the affected side. Percussion shows hyper-resonant notes and added sounds are absent.

Investigations

• X-Ray chest shows increased translucency without lung markings on the affected side. Lung is collapsed towards the midline and is seen as a dense lesion close to the hilum. Radiographic manifestations of tension pneumothorax are mediastinal shift, depression of diaphragm and rib cage expansion.

• In a supine film taken in ICU, pneumothorax is often missed as the collapsed lung overlaps the air shadow. The presence of a deep costophrenic angle (deep sulcus sign) may be the only sign.

• CT may be necessary to diagnose pneumothorax in critically ill patients in whom upright or decubitus films are not possible3. CT demonstrates focal areas of emphysema or bleb in spontaneous pneumothorax.

Treatment4

• Based on five principles which are, removal of air, reducing air leakage, healing the pleural fistula, promoting re-expansion and preventing recurrences.

• Treating underlying diseases, preventing, and dealing complications are also important.

Treatment of pneumothorax is depended on:

• Size of the pneumothorax

• Symptoms

• Underlying lung disease

According to the British Thoracic Society (BTS) guidelines5, pneumothorax is measured from the inner chest wall to the lung edge at the level of the hilum.

• <2 cm- small pneumothorax.

• ≥2 cm- large pneumothorax.

• If asymptomatic no treatment is recommended for small pneumothorax. Follow-up radiology is advised to confirm resolution.

• Pneumothorax with mild symptoms without any underlying lung condition, needle aspiration is advised. Needle aspiration is as effective as large-bore chest drains. 

• But if failed, needle aspiration should not be repeated and a small-bore (<14 F) chest drains is inserted. Cannula connected to one-way Heimlich valve devices or small-bore pigtail catheters are also used.

• Pneumothorax in a patient with underlying chronic lung disease or large pneumothorax with significant symptoms should be treated with intercostal drain. The distal drainage device includes a water seal bottle and negative pressure suction device.

• Pleurodesis is considered in patients with recurrence pneumothorax. Pleurodesis is indicated in second ipsilateral recurrence or first contralateral recurrence. Chemical pleurodesis with talc under medical thoracoscopic guidance is preferred.

 References

1. Sahn SA, Heffner JE. Spontaneous pneumothorax. N Engl J Med. 2000; 342(12):868-74. [Medline].

2. Mitlehner W, Friedrich M, Dissmann W. Value of computer tomography in the detection of bullae and blebs in patients with primary spontaneous pneumothorax. Respiration. 1992; 59(4):221-27. [Medline].

3. Lesur O, Delorme N, Fromaget JM, et al. Computed tomography in the etiologic assessment of idiopathic spontaneous pneumothorax. Chest. 1990; (2):341-47. [Medline].

4. Tschopp JM, Rami-Porta R, Noppen M, Astoul P. Management of spontaneous pneumothorax: state of the art. Eur Respir J. 2006; (3):637-50. [Medline].

5. MacDuff A, Arnold A, Harvey J, et al. Management of spontaneous pneumothorax: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010; 65 (Suppl 2):ii18-31. [PubMed]