Pneumothorax.

Pneumothorax.

Presence of air in the pleural cavity is known as pneumothorax.

Aetiology

Primary (simple) spontaneous pneumothorax commonly affects tall, slender males between the ages of 20 and 40 years. It is believed to be due to rupture of subpleural blebs at the lung apices.

Rupture of emphysematous bullae.

Rupture of a subpleural tuberculous focus.

Rupture of a lung abscess, especially staphylococcal.

Bronchial carcinoma. o Pulmonary infarction. o Bronchial asthma.

Acute respiratory distress syndrome (ARDS).

Rare causes include sarcoidosis, Pneumocystis jiroveci pneumonia and cystic fibrosis.

Clinical features

A small pneumothorax may be asymptomatic with no abnormal physical signs in the chest. o Sudden onset chest pain and dyspnoea are the most common symptoms.

Physical signs

General examination may reveal cyanosis, rapid thready pulse, pulsus paradoxus and signs of peripheral circulatory failure in severe cases.

Inspection and palpation of respiratory system reveals dyspnoea, shallow breathing, accessory muscles of respiration in action, shift of trachea and mediastinum (apex beat) to the opposite side, fullness of the chest on the affected side, diminished chest movements and markedly diminished vocal fremitus on the affected side. Measurements show a reduction in total chest expansion, increase in the size of the affected hemithorax, diminished expansion of the affected hemithorax and increased spinoscapular distance.

Percussion note is hyper-resonant over the affected hemithorax. The liver dullness is obliterated and cardiac dullness is shifted to the opposite side.

Auscultation reveals markedly diminished-to-absent breath sounds, absence of adventitious sounds and markedly diminished vocal resonance. In an open pneumothorax with a bronchopleural fistula, amphoric bronchial breathing may be heard. Coin test may be positive. Two coins when tapped on the affected side produce a tinkling resonant sound which is audible on auscultation.

Radiological findings on chest radiograph

Mediastinal shift to the opposite side

Sharply defined edge of the deflated lung

Complete translucency and absence of bronchovascular markings in the area between the edge of the lung and chest wall

Presence or absence of a complicating empyema

Presence or absence of underlying lung lesion

Types of pneumothorax

There are three types of spontaneous pneumothorax:

1.Closed spontaneous pneumothorax.

2.Open spontaneous pneumothorax.

3.Tension (valvular) pneumothorax.

Types of spontaneous pneumothorax

Closed spontaneous pneumothorax

The communication between pleura and lung seals off and does not reopen. Air can neither enter nor leave the pleural space. The trapped air is slowly re-absorbed, and the lung re-expands completely in 2-4 weeks.

Clinically, closed pneumothorax manifests as trivial breathlessness which gradually abates over a few days. Pleural space infection is uncommon.

Treatment

Asymptomatic or slightly breathless patients with small pneumothorax need no treatment, but only serial radiographic monitoring is required till the lung re-expands.

If the patient is breathless and the pneumothorax is large, it should be treated actively by one of the following methods:

Inserting a catheter into the pleural cavity and connecting it to a water-seal drainage system or a non-return valve.

Evacuation of the air using a syringe and needle, a three-way tap and an underwater-seal system. Open spontaneous pneumothorax

The communication between bronchus and pleura does not seal off and remains patent, resulting in a 'bronchopleural fistula'. Since air can freely flow through the bronchopleural fistula, intrapleural pressure and atmospheric pressure remain the same throughout the respiratory cycle. This prevents the re-expansion of the collapsed lung. In addition, bronchopleural fistula facilitates spread of infection into the pleural space resulting in empyema.

Open pneumothorax usually follows rupture of an emphysematous bulla, a small pleural bleb, a tuberculous cavity or a lung abscess into the pleural space.

Clinically, the patient presents with breathlessness which does not improve. If pleural space infection sets in, fever and systemic disturbances ensue. The physical signs are those of air and fluid in the pleural space (hydropneumothorax). Treatment

This form of pneumothorax usually requires surgical closure though a trial with chest tube insertion with low-pressure suction may be tried. Various modalities of surgical closure are the following:

Cauterisation of the opening.

Thoracoscopic cutting and release of adhesions which prevent the closure of the fistula.

Open thoracotomy and direct closure of the fistula.

Tension (valvular) pneumothorax

The communication between pleura and lung persists. It acts as a one-way valve allowing air to enter the pleural space during inspiration, coughing, sneezing and straining, but not allowing it to escape.

Large amounts of air gets 'trapped' in the pleural space and the intrapleural pressure becomes much higher than the atmospheric pressure.

The high intrapleural pressure results in compression of the underlying lung, as well as gross shift of the mediastinum to the opposite side with consequent compression of the opposite lung also. It also reduces venous return by compressing the vena cavae.

Clinically, these patients present with rapidly progressive breathlessness, central cyanosis, rapid thready pulse and signs of peripheral circulatory failure. Frank signs of pneumothorax are present. Death can occur within few minutes from asphyxia.

Treatment

Tension pneumothorax is an acute medical emergency.

Emergency treatment is the introduction of a wide-bore plastic cannula, the other end of which is attached to a long rubber tubing, the end of which is placed underwater in a bottle.

The better alternative is the introduction of an intercostal catheter connected to a water-seal drainage system.

Recurrent spontaneous pneumothorax

Recurrent episodes of pneumothorax are common in patients with emphysematous bullae. The episodes usually occur on the same side.

The treatment includes obliteration of the pleural space by artificial pleurodesis. This can be accomplished by intrapleural instillation of an irritant like tetracycline hydrochloride or talc powder. Alternatively, pleural abrasion or parietal pleurectomy at thoracotomy may be attempted.

Catamenial pneumothorax

This is a rare condition occurring in females over 25-30 years. Repeated attacks of spontaneous pneumothorax occur, usually on the right side, in association with menstruation. Attacks usually occur within 48 hours of the onset of menstruation.

Various treatment modalities attempted include ovulation-suppressing drugs, surgical exploration and pleurodesis.

Clicking pneumothorax

A small left-sided pneumothorax may get localised in front of the pericardium. This may alter the heart sounds to make them sound loud and resonant ('clicking').