Pneumothorax and insertion of a chest drain

Pneumothorax and insertion of a chest drain

CARDIOTHORACIC II Pneumothorax and insertion of a chest drain Pathophysiology A pneumothorax occurs when either the visceral or parietal pleura are ...

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CARDIOTHORACIC II

Pneumothorax and insertion of a chest drain

Pathophysiology A pneumothorax occurs when either the visceral or parietal pleura are breached causing air to enter the pleural space, leading to loss of the negative intrapleural pressure and lung collapse.

Eustace J Fontaine A simple pneumothorax is the most common type and occurs when air from the lung enters the pleural space. As the lung 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.

Richard D Page

Abstract A pneumothorax occurs when the visceral or parietal pleura is breached and air enters the pleural space. This leads to loss of the negative intrapleural pressure and lung collapse. Pneumothoraces may be classified into ‘simple’, ‘tension’ or ‘open’ according to the underlying pathophysiology. A chest radiograph is essential in diagnosis and management. Tension pneumothorax is a medical emergency, relieved initially with needle thoracentesis, but treated definitively with a chest drain. The latter is inserted in all cases where aspiration is unsuccessful in controlling symptoms in a simple pneumothorax. A thoracic surgical opinion should be sought if there is persistent air leak from the drain or the lung fails to re-expand after three days. A chest drain is used to drain air, blood, fluid or pus from the pleural space. Proper attention should be paid to patient preparation, which should include full asepsis, appropriate patient positioning, and application of National Patient Safety Agency recommendations. A chest drain is usually inserted under local anaesthesia in the ‘safe triangle’ in the lateral chest wall using blunt dissection. The drains should not be clamped in cases of pneumothorax, and the drainage bottle should always be kept below the level of the patient’s chest.

A tension pneumothorax 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 also life-threatening. It implies preferential movement of air in and out of the thorax via a large defect in the chest wall during respiration.

Aetiology Primary spontaneous pneumothorax occurs in the absence of underlying lung disease, typically tall, young males (20e30 years) who smoke. It is caused by rupture of a subpleural bleb (an airfilled space between the lung parenchyma and the visceral pleura). The lungs are normal with the exception of these subpleural blebs, which are most commonly located at the apices of the lung or along the fissures. It is slightly more common on the right side.

Keywords chest drain; chest surgery; effusion; empyema; pleura; pleurectomy; pneumothorax; thoracocentisis; trauma; video-assisted thoracic surgery

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 which can be a particularly difficult problem as positive pressure ventilation always makes air leaks from the lung more troublesome, whatever the underlying pathology may be. Pneumothorax may rarely be the first manifestation of a thoracic malignancy.

Anatomy The visceral pleura is a very thin membrane which is tightly adherent to the outer surface of the lung. It is continuous at the hilum of the lung with the parietal pleura which covers the internal aspect of each hemithorax (mediastinum, diaphragm, chest wall and apex of the chest). A closed potential space exists between the two pleurae filled with a film of fluid secreted by the mesothelial lining of the pleural surfaces. There is a near constant negative intrapleural pressure ( 0.5 kPa), which results from elastic recoil of the lungs away from the chest wall thus preventing lung collapse.

Catamenial pneumothorax typically occurs within 2e3 days from the onset of menstruation in women aged 30e40 years with a history of pelvic endometriosis. It occurs on the right side in 90% of cases and accounts for 3e6% of spontaneous pneumothorax in women. Traumatic pneumothorax may be iatrogenic (e.g. following central line insertion, percutaneous lung biopsy, and pleural aspiration) or due to blunt or penetrating trauma. The presence of surgical emphysema or multiple rib fractures in the trauma patient strongly suggests a pneumothorax and lung injury. Other causes are rupture of the intrathoracic oesophagus due to a forceful vomit (Boarhaave’s syndrome) or iatrogenic perforation at endoscopy.

Eustace J Fontaine MSc FRCS(CTh) is a Specialist Registrar in Thoracic Surgery at the Liverpool Heart and Chest Hospital NHS Foundation Trust, Liverpool, UK. Conflicts of interest: none. Richard D Page ChM FRCS(CTh) is a Consultant Thoracic Surgeon at the Liverpool Heart and Chest Hospital NHS Foundation Trust, Liverpool, UK. Conflicts of interest: none.

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Diagnosis

mildly symptomatic spontaneous pneumothoraces. Patients with secondary pneumothorax <1 cm with minimal symptoms should be hospitalized and observed whereas patients with small primary spontaneous pneumothoraces can be discharged and told to return if their symptoms deteriorate. Pleural aspiration is recommended as first-line treatment for primary pneumothoraces requiring intervention. It is less successful in secondary pneumothorax. Aspiration can be repeated but a chest drain may be required if the pneumothorax and symptoms fail to resolve. The chest drain is connected to an underwater seal drainage system; high-volume, low-pressure ( 2.5 kPa to 5 kPa) suction may be applied for a persistent air leak that prevents reexpansion of the lung. The opinion of a thoracic surgeon should be sought if there is a persistent air leak from the drain or if the lung fails to re-expand after three days. Open thoracotomy or video-assisted thoracic surgery allows closure of air leaks, as well as achieving pleural symphysis with either a 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.

The most common presenting symptom is pleuritic pain followed by dyspnoea. The severity of symptoms does not correlate with the size of the pneumothorax. A large pneumothorax may be associated with reduced chest wall movement, resonance to percussion, reduced or absent tactile fremitus, and absent or reduced breath sounds on the affected side. Tracheal deviation away from the side of the pneumothorax suggests tension pneumothorax. The examination may be normal for a small pneumothorax. An erect posteroanterior radiograph of the chest in inspiration is usually sufficient to diagnose and estimate the size of a pneumothorax. Occasionally diagnosis is more difficult as illustrated by the radiograph in Figure 1. A computed tomography (CT) scan of the chest may be helpful when the diagnosis is in doubt especially in cases where extensive surgical emphysema is present, and to diagnose complications of pneumothorax such as empyema and haemothorax.

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.

Procedure for insertion of chest drain A chest drain removes air, blood, fluid or pus from the pleural space. It re-establishes negative intrapleural pressure when connected to an underwater seal. There is a risk of major complications as a consequence of chest drain insertion (Box 1); the

Open pneumothorax e the defect in the chest wall is occluded by a square dressing secured on three sides, thus acting like a flap valve.

Complications of chest drains

Spontaneous pneumothoraces e management is determined by the severity of symptoms, degree of lung collapse, and whether primary or secondary. A visible rim of air <2 cm or 2 cm on chest radiograph between the lung margin and chest wall describe a small and large pneumothorax respectively. A rim of 2 cm approximates to a 50% pneumothorax in terms of loss of volume of the lung. Observation is the first-line treatment for small, closed,

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 Other Surgical emphysema Re-expansion pulmonary oedema Intercostal neuralgia

Figure 1 A chest radiograph in a patient with a right-sided pneumothorax and a large emphysematous bulla on the left. There are lung markings visible peripherally in relation to the bulla which are not present on the side of the pneumothorax.

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CARDIOTHORACIC II

parietal pleura. In all patients fluid or air should be aspirated confirming entry into the pleural space and the underlying diagnosis and is a useful guide to its distance from the surface. Insertion A 2e3 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 the drain has a metal trocar it should be either removed completely or at least withdrawn so the sharp end is contained within the drain to avoid damage to intrathoracic structures. If there is any difficulty at this stage, it may be appropriate to gently 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). The chest drain is connected to an underwater seal 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.

Figure 2 The ‘safe triangle’ (cross-hatched) for insertion of a chest drain is bordered by the anterior border of the latissimus dorsi (yellow), lateral border of pectoralis major (red), a line at the horizontal level of the nipple (in men) or base of the breast (in women) and the apex below the axilla.

National Patient Safety Agency published a report in May 2008 (NPSA/2008/RRR03) on the potential for harm associated with chest drain insertion and highlighted the need for hospitals ensuring appropriate competencies, supervision and training for all aspects of chest drain management, and the use of ultrasound for draining pleural effusions. Although the recommendations regarding the use of ultrasound do not apply to pneumothorax, experience with this type of imaging by all clinicians involved in chest drain insertion is an asset to ensure tube placement above the diaphragm and avoid puncture of abdominal viscera. 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.

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 syphoning of the underwater seal contents into the pleural space.

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 45 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.

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. A

Site and analgesia The commonest position for insertion of a chest drain is through the ‘safe triangle’ (Figure 2). Local anaesthesia (1% or 2% lidocaine, maximum 3 mg/kg) should be infiltrated into the skin, subcutaneous tissues, intercostal muscles and underlying

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