lying lung pathology. It typically occurs spontaneously in tall, thin, young men, but may occur in any subject. It is due to rupture of small subpleural blebs or bullae, but overall the lung parenychma appears normal. Secondary pneumothorax occurs in the presence of underlying lung disease such as emphysema, malignancy and pulmonary fibrosis. Therefore, it may be less well tolerated than in a healthy individual, and require earlier intervention and close medical supervision. Traumatic pneumothorax may result from blunt or penetrating trauma to the chest (see respective articles on pages 114 and 117). A high level of suspicion should be maintained in any patient presenting with chest or multiple trauma. The presence of pulmonary contusions, surgical emphysema or multiple rib fractures is highly suggestive of an underlying lung injury. In such circumstances, the elective insertion of an intercostal drain (see below, CROSS REFERENCE) before positive-pressure ventilation for surgery or transfer may stop a simple pneumothorax being transformed into a life-threatening tension pneumothorax. Iatrogenic traumatic pneumothorax may occur during placement of central venous lines, particularly via the subclavian route or during positive-pressure ventilation.
Pneumothorax and insertion of a chest drain Timothy J Jones P B Rajesh
Pathophysiology Safe management of pneumothorax (air in the pleural space) requires an understanding of the intrapleural pathophysiology. The lungs are enveloped by the visceral pleura which, at the hilum, become continuous with the fibrous parietal pleura covering the mediastinum, diaphragm and inner wall of the chest. The parietal and visceral pleura are separated by the narrow, fluid-filled pleural space. The lungs are elastic and therefore have a tendency to recoil from the chest wall, so at rest the intrapleural pressure is less than atmospheric pressure (-0.3 kPa). This negative pressure keeps the pleural layers in contact and stops the lung collapsing. A pneumothorax occurs when the pleural space is breached, following disruption of either the visceral or parietal pleura. Air enters the pleural space, resulting in loss of the negative intrapleural pressure and collapse of the lung. Simple pneumothorax is the most common type of pneumothorax. The pleural disruption either seals itself or continues to allow air to flow in and out of the pleural space with each respiration. The negative intrapleural pressure is lost and the lung remains collapsed. Open (sucking) pneumothorax is more serious and may be immediately life-threatening if untreated. If there is a large defect in the chest wall, air will move in and out of the defect (as opposed to via the airways during respiration) and self-ventilation will not occur. This is due to the defect presenting less resistance to airflow than the trachea and bronchi. Tension pneumothorax is a life-threatening condition. If, during each respiratory cycle, air is able to enter but not leave the pleural space via a defect acting as a one-way valve, the pressure in the pleural space will increase. If undiagnosed, the increasing pressure will cause compression of the contralateral lung, mediastinal deviation and impairment of venous return to the heart, resulting in electromechanical dissociation and death.
Management Tension pneumothorax is a medical emergency. It is a clinical diagnosis and, if suspected, should be treated with immediate needle thoracocentesis in the second intercostal space, midclavicular line followed by placement of an intercostal drain. Open pneumothorax requires immediate treatment with the application of a square dressing secured on three sides to act as a flap valve. Simple pneumothorax – management depends upon the clinical condition, and the size of the pneumothorax. The latter is based upon the distance of lung from the chest wall: <2 cm is a small pneumothorax and ≥2 cm is a large pneumothorax. The indications for aspiration or drainage of a simple pneumothorax are size (≥2 cm) or the presence of symptoms (breathlessness). An asymptomatic patient with a pneumothorax <2 cm may be managed conservatively. Aspiration may be attempted as a first-line intervention in all simple primary pneumothoraces. It is less likely to be successful in secondary pneumothoraces, because they usually require insertion of an intercostal drain.
Insertion of an intercostal drain The purpose of an intercostal drain is to drain the pleural space of air, blood, fluid or pus and to re-establish negative intrapleural pressure. Preparation – the procedure should be explained to the patient and consent obtained. Unless there are contraindications, and time permitting, premedication with opiates or benzodiazepines should be used. The patient should be sitting at 45o on a bed with the arm abducted to expose the axilla. All equipment should be at the bedside. The site and side of insertion should be reconfirmed clinically and radiologically. Aseptic technique – there is always time for minimum sterile preparation. Sterile gown, gloves, towels and instruments should be used after antiseptic skin cleansing.
Causes Pneumothoraces may be further classified as primary, secondary or traumatic. Primary pneumothorax occurs without any obvious under-
Timothy J Jones is a Specialist Registrar in Paediatric Cardiac Surgery at Birmingham Children’s Hospital, Birmingham, UK. P B Rajesh is a Consultant Thoracic Surgeon at Birmingham Heartlands Hospital and Honorary Senior Lecturer at Birmingham University, Birmingham, UK.
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Site – an intercostal drain should never be inserted through a stab wound or via a previous drain site. Drains should be inserted in the ‘triangle of safety’ (Figure 1). The most common position is the fifth intercostal space (nipple level) in the anterior axillary line. Analgesia – adequate quantities of local anaesthetic (1% or 2% lidocaine, up to 3 mg/kg) should be infiltrated into the skin, subcutaneous tissues, periosteum of the rib and underlying pleura. Using the needle to aspirate air or fluid confirms entry into the chest. Insertion – using a scalpel, a 2–3-cm skin incision is made parallel to the rib. Artery forceps are used with a spreading action to dissect the subcutaneous tissues bluntly and safely to the upper border of the rib. The pleura is entered with the forceps over the top of the rib. A finger is used to make a 360o sweep of the inside of the chest to ensure correct location (thorax and not abdomen) and to clear clots and adhesions. The trocar should always be removed from the drain and discarded. Using an arterial or sponge-holding forceps, the chest tube is inserted into the chest and connected to an underwater drainage system. Once connected, visualize the ‘respiratory swing’ of fluid in the drainage tubing, which confirms that the drain is in the pleural space. Securing the drain – a non-absorbable 1/0 or larger suture is used to secure the drain. A second suture is placed as a loose mattress stitch to act as a ‘purse-string’ for tying when the drain is removed. The site is then dressed with a gauze dressing before obtaining a chest radiograph.
Complications of chest drains Neurovascular damage Visceral perforation
Infection Incorrect placement of tube Tube complications
Tension pneumothorax Subcutaneous emphysema Re-expansion pulmonary oedema 2
Suction is often required to aid re-expansion of the lung or if there is an air leak. Only high-volume, low-pressure (2–3 kPa) suction should be used. Complications of drains are listed in Figure 2. Removal of drains – there is often confusion regarding the timing of removal. The presence of a ‘respiratory swing’ of fluid in the tubing demonstrates that the drain is in the pleural space; loss of respiratory swing indicates that the drain is either blocked or is no longer in the pleural space. • Following pneumothorax, the drain should be removed when there has been no air leak (bubbling) for 24 hours with the drain off-suction and the lung fully expanded. • For pleural effusion, the drain can be removed when it is losing <100 ml in 24 hours. • In empyema (see page 103), the drain should be completely dry before removal. The securing suture is cut, the patient takes a deep inspiration and the drain is promptly removed whilst tying the purse-string suture. A chest radiograph must be obtained after removing the drain to ensure that the lung remains expanded.
General management of intercostal drain Chest drains should never be clamped. The only time when it is appropriate to clamp a drain is when there is massive, life-threatening exsanguination via the drain. The drainage bottle should always be maintained below the level of the patient’s chest to prevent siphoning of the bottle contents back into the chest. Lung expansion and drain position should be confirmed by inspection of a daily radiograph of the chest. The drain site should be regularly inspected for signs of infection.
FURTHER READING Henry M, Arnold T, Harvey J, Pleural Diseases Group. BTS guidelines for the management of spontaneous pneumothorax. Thorax 2003; 58: 39–52. Hyde J A J, Jones T J J, Graham T R. The management of intercostal drains. In: Greaves I, Ryan J M, Porter K M, Editors. Trauma. London: Edward Arnold, 1998. Laws D, Neville E, Duffy J. Pleural Diseases Group. BTS guidelines for the insertion of a chest drain. Thorax 2003; 58: 53–9.
The pink area represents the ‘triangle of safety’—an area bound by the lateral border of pectoralis major superiorly, the anterior axillary line posteriorly and the sixth rib inferiorly. It represents a safe area for insertion of an intercostal chest drain. Care should be taken to avoid the axillary tail of the breast.
CROSS REFERENCE Thorpe A, Pappagianopoulos K, Kumar B. Quiz. Surgery 2003; 21(5): 128g.
Bleeding Intercostal neuritis Lung Heart/great vessel Abdominal organ Superficial Empyema Extrapleural Abdominal Blockage Dislodgement Disconnection Blocked tube
© 2004 The Medicine Publishing Company Ltd