Epidemiology

PSP has an incidence of 7.4 to 18 cases (age-adjusted incidence) per 100,000 population each year in males and 1.2 to 6 cases per 100,000 population each year in females^[4,7]. PSP typically occurs in tall, thin subjects. Smoking plays a role in the development of PSP. The lifetime risk in healthy smoking men may be as much as 12% compared with 0.1% in non-smoking men. PSP recurs in up to 25% of the cases after a first episode and up to 50% after a second episode, especially in the first 2 years after the initial episode. There are, therefore, two distinct epidemiological forms: (1) primary pneumothorax, with a peak incidence in young people between 20 and 40 years old, especially if the person is very tall and underweight, and (2) secondary pneumothorax, which has a peak incidence in those aged above 55 years. Because lung function in these patients is already compromised, SSP can be more serious. The general incidence is almost similar to that of PSP.

Pathogenesis

The pathogenesis of the spontaneous occurrence of a communication between the alveolar spaces and the pleura remains unknown. Subpleural blebs and bullae are found at the lung apices at thoracoscopy and on computed tomographic (CT) scanning in up to 90% of cases of PSP^[5,14,15].

Smoking is implicated. The risk increases with the length of time and the number of cigarettes smoked. It has been associated with a 12% risk of developing pneumothorax in healthy smoking men compared with 0.1% in non-smokers. The risk of recurrence of PSP is as high as 54% within the first 4 years and in 80–86% of young patients who continue to smoke after their first episode of PSP.

Signs and symptoms

Symptoms in PSP may be minimal or absent. In contrast, symptoms are often greater in SSP, even if the pneumothorax is relatively small in size. The typical symptoms are chest pain and dyspnoea. Almost all patients with PSP report a sudden ipsilateral chest pain. Dyspnoea may be present but is usually mild. In SSP, dyspnoea is the most prominent clinical feature; chest pain, cyanosis, hypoxemia and hypercapnia, sometimes resulting in acute respiratory failure, can also be present. Physical examination can be normal in a small pneumothorax. In a large pneumothorax, breath sounds and tactile fremitus are typically decreased or absent, and percussion is hyper-resonant. Severe symptoms and signs of respiratory distress suggest the presence of tension pneumothorax, which is, however, extremely rare in PSP. These signs include

Clinical evaluation should probably be the main determinant of the management strategy.

Diagnostic approaches of SP

The diagnosis of pneumothorax is usually confirmed by imaging techniques. The following imaging modalities are employed for the diagnosis and management of pneumothorax:

Standard erect PA chest radiographs in inspiration are recommended for the initial diagnosis of pneumothorax rather than expiratory films. The diagnostic characteristic is displacement of the pleural line. If uncertainty exists, then CT scanning is highly desirable.

Lateral X-rays may provide additional information when a suspected pneumothorax is not confirmed by a PA chest film.

CT scanning can be regarded as the ‘gold standard’ in the detection of small pneumothoraces and in size estimation. It is generally performed before surgery in patients >40 years old (either smokers or non-smokers). The 2010 British Thoracic Surgery guidelines recommend using CT when required to differentiate between pneumothorax and bullous lung disease, when aberrant tube placement is suspected and when the plain chest radiograph is difficult to read owing to the presence of subcutaneous emphysema (grade C recommendation).

Treatment

The chief objective of the management of primary spontaneous pneumothorax is elimination of the intrapleural air, either by observation in the case of partial pneumothorax or by evacuation using any of several different methods when the pneumothorax is complete and/or there is total lung collapse.

The secondary aim is to prevent recurrence when there is a high probability of recurrence or when recurrence could potentially be serious.

Treatment options for PSP include

Observation. This should be the first-line treatment for patients who have a partial pneumothorax and no dyspnoea (grade B recommendation). If the lung is less than 20% collapsed, monitoring of the patient’s condition with a series of chest X-rays can be done, until the air in the pleural space is completely absorbed and the lung has re-expanded. The reabsorption rate is 1.25 to 1.8% per day. A 25% pneumothorax will take 20 days to resolve.

Needle aspiration (thoracentesis). When the lung is more than 20% collapsed, the air in the pleural space can be removed by inserting a needle or hollow tube (chest tube). This can be done even when the pneumothorax is small and non-threatening, because it may take weeks for it to heal on its own^[18]. Thoracentesis is associated with less pain, and patients do not have to be admitted to hospital. The rate of immediate resolution ranges between 50 and 88%. Several randomized clinical trials have shown this procedure to be as effective in both the short and long term as chest tube drainage (grade A recommendation).

Chest (intercostal) tube drainage. This is the most common approach, even if there is a trend towards a non-surgical approach in most countries. Small-bore catheters (14F) are easier to insert and cause less discomfort (grade B recommendation). Intercostal tube drainage (16F–24F) are very popular. During this procedure, chest (intercostal) tubes are connected to a one-way valve system that allows air to escape but not to re-enter the chest cavity and may be left in place for several hours to several days^[6].

Indications for surgery:

The aforementioned professions are considered unsafe unless permanent treatment of spontaneous pneumothorax has been achieved; in some instances, professional guidelines suggest that pleurodesis is performed on both lungs and that lung function tests and CT scan must be normal before normal activity is resumed.

There are two objectives in the surgical management of pneumothorax. The first widely accepted objective is resection of blebs or the suture of apical perforations to treat the underlying defect. The second objective is to create a pleural symphysis (pleurodesis) to prevent recurrence. There are three options: pleurectomy, abrasion, and talc poudrage.

Video-assisted thoracoscopy (VATS) is the ‘gold standard’ for surgical treatment of PSP. It is a less invasive approach and has the benefits of less post-operative pain, better wound cosmetics, shorter duration of drainage and hospital stay, better functional recovery, better short- and long-term patient satisfaction, and at least equivalent cost-effectiveness to the open approach. Video-assisted magnification allows easier identification of the bullae or blebs, which can be managed through VATS in different ways: stapling and resection, which is the commonest approach; by no-knife stapling, useful in emphysematous-like lung; or by endoloop ligation, which has been shown by Cardillo et al. to be less effective than the previous techniques^[11]. However, bullectomy without additional pleurodesis does not prevent recurrence as effectively as combining the two techniques. Horio and Naunheim have shown that recurrence rate diminished from 16 to 1.9% and from 20 to 1.5%, respectively, when a pleurodesis was added to bullectomy^[13,16]. Cardillo has shown bullectomy to be superior to bulla ligation (endoloop) with a drop of recurrence rate from 4.54 to 0%. Bullectomy with pleural abrasion or with talc poudrage is the technique most often used by most thoracic surgeons (grade D recommendation)^[1,2,20].

The different pleurodesis techniques (pleurectomy, pleural abrasion and talc poudrage) have all shown to be effective in preventing recurrences^[19]. Parietal pleurectomy is often extended from the apex to the fifth–sixth intercostal space or lower. Pleural abrasion is usually performed with a pad. Talc pleurodesis is performed by instilling 2–4 g of sterile talc in the pleural cavity. It is a very fast technique, with the lowest rate of related complications, compared to the risk of bleeding reported for pleurectomy, and sometimes, even for pleural abrasion. Talc poudrage has been shown to be efficacious and safe with a success rate of 95% in the largest series. No concern exists regarding the oncological safety of talc and about the long-term lung function after talc poudrage. Graded talc, with a very low percentage (4–5%) of particles with a diameter of less than 5 microns, has been extensively and safely used in Europe for more than 70 years for pleurodesis in recurrent spontaneous pneumothorax and has been shown to be well tolerated without long-term sequelae^[9–12].