incidence of spontaneous pneumothorax in the UK is 16.7 per 100,000 for men and 5.8 per 100,000 for women. Secondary spontaneous pneumothorax occurs due to underlying lung disease (e.g. bullous emphysema). Severe infections of the lung in patients requiring artificial ventilatory support may also result in pneumothorax; this can be a particularly difficult problem because positive-pressure ventilation makes air leaks from the lung more troublesome, whatever the underlying disease. Pneumothorax may be the first manifestation of a thoracic malignancy (rare). Post-traumatic pneumothorax may result from penetrating or blunt trauma to the chest (see pages 406 and 409, respectively). Multiple rib fractures and surgical emphysema strongly suggest an underlying pneumothorax and lung injury; if positive-pressure ventilation is required for any reason, insertion of a chest drain prevents a simple pneumothorax from becoming a life-threatening tension pneumothorax. Other causes of pneumothorax include oesophageal trauma due to spontaneous rupture (Boarhaave’s syndrome) or iatrogenic perforation during oesophagoscopy.
Pneumothorax and insertion of a chest drain Nilanjan Chaudhuri Richard D Page
Anatomy The visceral pleura is tightly adherent via elastic fibres to the lung, and is continuous at the hilum with the parietal pleura (a serous membrane covering the mediastinum), chest wall (inner surface) and the diaphragm. A closed potential space, containing a thin layer of fluid (0.01 mm; <1 ml) exists between the visceral and parietal pleurae. The elastic lung tends to recoil from the chest wall, thus creating a subatmospheric intrapleural pressure (–0.5 kPa) at rest, which prevents lung collapse.
The sudden onset of dyspnoea and pleuritic chest pain, reduced entry of air, resonance to percussion, and tracheal deviation suggest a pneumothorax. An erect posteroanterior radiograph of the chest in inspiration is essential to reliably diagnose and estimate the size of a pneumothorax. CT of the chest may be required to investigate secondary pneumothoraces or diagnose a post-traumatic pneumothorax in extensive surgical emphysema.
A pneumothorax occurs when the visceral or parietal pleura are breached and air enters the pleural space, leading to loss of the negative intrapleural pressure and lung collapse. A simple pneumothorax is the most common type and occurs when air from the lung enters the pleural space. As the lung partially collapses, the air leak usually seals itself spontaneously, and the intrapleural pressure remains negative relative to the atmosphere. There is no loss of function of any other intrathoracic organs other than the affected lung. A tension pneumothorax is life-threatening and occurs if air is able to enter the pleural space with each breath despite complete collapse of the lung. Progressively increasing positive intrapleural pressure causes deviation of the mediastinum away from the pneumothorax, which compresses the contralateral lung and impairs venous return to the heart. Eventually, death results from a combination of absence of ventilation of either lung, and electromechanical dissociation of the heart. An open (sucking) pneumothorax due to chest trauma is lifethreatening. It implies preferential movement of air in and out of the thorax via a large defect in the chest wall during respiration.
Management A tension pneumothorax is a medical emergency and, if suspected clinically (even without confirmation on chest radiograph), should be treated with immediate needle thoracocentesis in the second intercostal space in the mid-clavicular line, followed by insertion of a chest drain. Open pneumothorax – the defect in the chest wall in an open pneumothorax is occluded by a square dressing secured on three sides, thus acting like a flap valve. Other pneumothoraces – management is determined by the severity of symptoms and the degree of lung collapse. Observation is the first-line treatment for small pneumothoraces (visible rim of <2 cm between the lung margin and the chest wall). Pleural aspiration is recommended as first-line treatment for primary pneumothoraces requiring intervention, as well as in some small secondary pneumothoraces. A chest drain is inserted if simple aspiration cannot control symptoms. High-volume, low-pressure (–1 kPa to –2 kPa) suction may be applied to a chest drain for a persistent air leak that prevents re-expansion of the lung. The opinion of a thoracic surgeon should be sought if there is a persistent air leak or if the lung fails to re-expand after four days. Open thoracotomy or video-assisted thoracic surgery allow closure of air leaks, as well as achieving pleural symphysis with parietal pleurectomy, pleural abrasion or surgical talc pleurodesis; instillation of talc via a chest drain (to achieve a pleurodesis) is an alternative if the patient is unwilling or unable to undergo surgery.
Aetiology Primary spontaneous pneumothorax occurs in the absence of underlying lung disease; typically, it occurs in tall, young male smokers. The most common cause is rupture of a small collection of air beneath the visceral pleura (a subpleural ‘bleb’) at the lung apex; the lung parenchyma is otherwise normal. The annual
Nilanjan Chaudhuri is a Specialist Registrar in Thoracic Surgery at the Cardiothoracic Centre, Liverpool, UK. Richard D Page is a Consultant Thoracic Surgeon at the Cardiothoracic Centre, Liverpool, UK.
© 2005 The Medicine Publishing Company Ltd
Complications of chest drains
A chest drain drains air, fluid or pus from the pleural space. It re-establishes negative intrapleural pressure when connected to an underwater seal. A number of small-bore chest drains can be inserted using a Seldinger technique with guidewires and dilators, but the description below applies to insertion of chest drains of size 20 F or more. Consent and premedication – the procedure should be fully explained to patients to ensure their full cooperation. Unless contraindicated, premedication with opiates or benzodiazepines is helpful in reducing discomfort. Position and preparation – equipment should be checked before starting. The patient should be reclining on the bed at 45º with the arm abducted to expose the axilla. The site and side of insertion should be confirmed clinically and radiologically. Full aseptic technique is essential to prevent secondary infection, except in the most extreme, life-threatening situations. Site and analgesia – the commonest position for insertion of a chest drain is through the ‘safe triangle’ (Figure 1). Local anaesthesia (1% or 2% lidocaine, maximum 3 mg/kg) should be infiltrated into the skin, subcutaneous tissues, intercostal muscles and underlying parietal pleura. Ultimately, the needle is used to aspirate fluid or air, which confirms entry into the pleural space and is a useful guide to its distance from the surface. Insertion – a 2–3 cm skin incision is made parallel to the rib. Curved artery forceps are used for blunt dissection of subcutaneous tissues and muscle along the upper border of the rib. The pleural space is entered and, using the forceps to guide it, a chest tube is advanced into the chest. If there is any difficulty at this stage, it may be appropriate to insert an index finger between the ribs to identify pleural adhesions and ensure correct location of the drain. If this cannot be confirmed, expert help should be sought and another site for the drain considered; alternatively, reconsider if insertion of a chest drain is necessary. In general, the most effective chest drains are the easiest to insert (e.g. drainage of a large pneumothorax is easy and leads to a rapid improvement in condition).
Incorrect placement of tube Soft tissues of chest wall Wrong pleural space Abdomen Visceral perforation Lung Abdominal organ (e.g. spleen, liver) Haemorrhage Cutaneous Intercostal arteries Heart or great vessels Infection Superficial Empyema Tube complications Obstruction Dislodgement Disconnection Surgical emphysema Re-expansion pulmonary oedema Intercostal neuralgia 2
The chest drain is connected to an underwater seal closed drainage system; air bubbles signify drainage of the pneumothorax. A respiratory swing of the column of fluid in the drain tubing confirms that the drain is in the pleural space. It is secured using a heavy non-absorbable suture (1/0 or larger). A mattress suture is also placed loosely across the skin incision for tying upon drain removal. A chest radiograph must be obtained as soon as possible after drain insertion to check for accurate positioning and ensure that the pneumothorax or effusion has been treated appropriately. General management – full aseptic technique should be used if manipulation of entry site of the drain is necessary (to prevent infection tracking alongside the drain into the pleural cavity). A single sterile gauze dressing is adequate. The application of dressings of several centimetres thickness, along with adhesive tape wrapped around the drain, should be condemned. In drains left in situ for an extended period, the drain retaining suture may cut out from the skin and need replacing, otherwise the drain will fall out. Chest drains should not be clamped in cases of pneumothorax. The drainage bottle must be kept below the level of the patient’s chest to prevent siphoning of the underwater seal contents into the pleural space. Complications of drains are listed in Figure 2. Drain removal should be individualized to the patient but, in general: • pneumothorax: no air leak for 24 hours with the lung fully expanded and off-suction • pleural effusion: drainage <100 ml in 24 hours • empyema: the drain should be dry for at least 24 hours. The drain is removed when the pleural pressure is momentarily positive (during forced expiration or while the patient performs a Valsalva manoeuvre) to prevent entry of air into the pleural space.
1 The ‘safe triangle’ (crosshatched) for insertion of a chest drain is bordered by the anterior border of the latissimus dorsi (yellow line), inferolateral border of pectoralis major (red line), a horizontal line (blue line) at the level of the nipple in men or base of the breast in women, with the apex (black line) below the axilla.
© 2005 The Medicine Publishing Company Ltd