Other thoracic disorders

The lungs

Lung cysts

Developmental. These may develop from the primitive lung buds near the trachea or main bronchi. There are no communications with the bronchi even though they are lined with respiratory epithelium and have a tendency to become infected. Removal is advised for this very reason.

Acquired. Lung cysts may contain air or fluid and may be single or multiple. The most common cause of multiple lung cysts is pulmonary hydatid disease, although this is unusual except in endemic areas. Air cysts (bullae) may be spontaneous but may be secondary to emphysematous degeneration (Fig. 47.31). In either case the cysts may become infected or compress functioning lung tissue and therefore some form of treatment is required.

Pulmonary sequestration

This describes a section of lung supplied by the aorta and draining into the systemic circulation. There is no communication with the remainder of the lung and the segment becomes multicystic and infected, therefore compromising the surrounding healthy lung tissue. An interlobar sequestration occurs within the lung substance and commonly presents in younger patients.

Many cases are discovered on routine chest radiography but others may present with recurrent chest infections and occasionally bloodstained sputum. The chest radiograph normally shows a rounded opacity and the lesion cannot be seen at bronchoscopy (Fig. 47.32). Arteriography demonstrates the abnormal communication from the aorta and treatment involves removing the affected lobe, taking care to divide the abnormal artery (which usually runs in the inferior pulmonary ligament) as the first stage in the resection.

Bronchiectasis

This is defined as chronic irreversible dilatation of the medium-sized bronchi. There are several causes but there are two basic mechanisms that account for this dilatation:

1. a weakening of the bronchial walls;

2. outward tension on the lung substance.

These may occur following a suppurative pneumonia or bronchial obstruction. The process often starts in childhood following a respiratory infection and slowly progresses during adult life. It is rarely confined to one lobe or even one lung, which precludes surgery in many cases. The incidence of severe bronchiectasis is falling thanks to the reduction in cases of whooping cough, measles and tuberculosis, and the improved management of infantile bronchiolitis. Inhalation of foreign bodies remains a potential cause of bronchiectasis and this possibility should be borne in mind.

Presentation. Some patients remain asymptomatic and the problem is discovered by chance on chest radiograph or postmortem. Usually there is a history of frequent chest infections from infancy with the production of copious volumes of sputum. In advanced cases foul-smelling sputum is produced with pain over the affected area, and there is weight loss and cachexia. Physical examination may be normal but often there is finger clubbing (in advanced disease), wheezing and consolidation over the affected lobe. Chronic nasal sinusitis may be a presentation and, in severe cases, amyloidosis may occur.

Investigation. A good posteroanterior chest radiograph will often show crowding of the lung markings on the affected side. A series of chest radiographs taken over two to three exacerbations may show persistent collapse or recurrent consolidation affecting the same area of lung. CT is now the investigation of choice.

Bronchography. This is rarely necessary to define which lobe(s) are affected; most surgeons would be satisfied with a CT scan. This investigation may need to be preceded by intensive physiotherapy and postural drainage to obtain adequate images.

Treatment. Removal of the bronchiectatic part of the lung is indicated when the disease is localised, and the respiratory function is adequate to cope, with a reduced lung volume. Conservative surgery to preserve functioning lung tissue should be employed at all times.

Tuberculosis

This infection remains a major health problem in less developed countries but is increasing in frequency in Western countries as a result of immigration and immunosuppression [human immunodeficiency virus (HIV) and chemotherapy]. It commonly presents in the lungs and, if untreated or inadequately treated, can lead to serious complications. There is commonly a chronic cough with haemoptysis, weight loss and night sweats. The diagnosis should be firmly established by Ziehl—Neelsen staining of bacteria in the sputum or culture in Lowenstein—Jensen medium before starring antituberculous chemotherapy. Characteristic chest radiographic changes in symptomatic patients may be diagnostic if cultures are persistently negative; as a very last resort chemotherapy may be tried for 2 weeks. An improvement in symptoms indicates that tuberculosis is the problem.

The mainstay of treatment is antituberculous chemotherapy for the individual and bacille Calmette—Guérin (BCG) immunisation for contacts, attention to hygiene and housing in the community. Combination chemotherapy is usually successful in treating the infection. Inadequate treatment or noncompliance leads to the development of resistant organ­isms. The course of treatment is often over 6 months and in some less developed countries this can result in noncompli­ance. Surgery is rarely indicated for tuberculosis in developed countries but, when it is, it must be combined with adequate antitubercular chemotherapy or the benefit of surgery will be lost.

Indications for surgery. Indications are:

  suspicious lesion on chest radiograph in which neoplasia cannot be excluded;

  chronic tuberculous abscess, resistant to chemotherapy;

  aspergilloma within a tuberculous cavity;

  life-threatening haemoptysis.

Surgery is indicated for certain situations and is always used in conjunction with chemotherapy. With effective treatment and earlier diagnosis, the role of surgery is gradually decreasing in the management of this condition.

Diagnosis. Surgical procedures may be necessary to establish the diagnosis if the disease is suspected clinically, but sputum or pus cultures are persistently negative.

Bronchoscopy. This has a higher diagnostic yield than expectorated sputum.

Open lung biopsy. Tissues from intrathoracic lymph nodes, lung and pleura may be found to contain tuberculous material.

The formation of a tuberculous empyema can result in fibrosis of the affected lung and its functional destruction. A tube thoracostomy may suffice in the early stages of empyema, but once a fibrous rim has formed an exploratory thora­cotomy with decortication, evacuation of pus and effective postoperative suction will be required. Complications such as aspergilloma in a chronic cavity, haemoptysis and localised carcinoma arising from a tuberculous scar may require lobectomy. Operations designed to collapse the lung, such as thoracoplasty, are occasionally used to collapse cavities.

Pulmonary vascular disease

A detailed discussion of all the diseases of pulmonary vasculature is beyond the scope of this book. However, pul­monary embolus is a major cause of morbidity and mortality and is discussed here, as is lung and heart—lung transplantation, which is indicated for end-stage pulmonary vascular disease.

Pulmonary embolus. This occurs following dislodgement of venous thrombi, generally from the femoral and iliac veins, and their subsequent impaction in the pulmonary vasculature. More unusual causes are fat embolus from multiple trauma, tumour embolus (renal carcinoma) and amniotic fluid. Pulmonary embolism accounts for over 20 000 deaths per year in the UK. Strategies aimed at preventing the development of thrombi in those at high risk (postsurgical patients, postmyocardial infarction and those who have previously had pulmonary embolus) include early mobilisation, low dose subcutaneous heparin and compression stockings. The presentation can vary according to the size, number and timing of embolic episodes.

Small emboli may pass unnoticed, giving rise to minor pleuritic chest pain. Pulmonary vascular hypertension may develop with repeated episodes. Larger emboli may give rise to pleurisy and haemoptysis with signs of pleural rub and crackles on auscultation. Massive emboli lead to haemodynamic collapse if the outflow to the right ventricle is obstructed. There is severe chest pain and acute shortness of breath. The clinical signs are of right heart failure with raised central venous pressure and tachycardia, and theme may be some changes on the ECG. A chest radiograph is often not helpful in the early stages but a ventilation—perfusion scan may show a mismatch, thereby confirming the diagnosis. A contrast-enhanced CT scan is the most accurate diagnostic technique.

Treatment:  acute minor pulmonary embolus. Small emboli do not require specific treatment but preventive measures are needed to prevent further episodes. These rake the form of systemic heparinisation in the first instance and then oral anticoagulation with warfarin or its derivatives. Recurrent emboli, even with adequate anticoagulation, may require treatment with an inferior vena caval filter.

Treatment:  acute massive embolus. This occurs when a large embolus obstructs the pulmonary vasculature and results in haemodynamic disturbance. There is often a history of one or more minor emboli before the current episode. The haemodynamic problems dominate the clinical picture of acute might heart failure with corresponding low cardiac output and acute ventilation—perfusion mismatch. Theme is peripheral vasoconstricrion, tachycardia with a small volume pulse and tachypnoea. Blood gas analysis ‘usually reveals a low Po2 from the ventilation—perfusion mismatch and a low Pco2 from the associated hyperventilation. The patient will usually be more comfortable lying flat, in contrast to the patient with myocardial infarction who prefers to sir upright. Once the diagnosis has been made, treatment with thrombolytic agents (streptokinase and tissue plasminogen activator) is started. The emboli are seen as filling defects in the pulmonary artery (Fig. 47.33). The immediate priority is to resuscitate the patient by administering intravenous fluids to increase the right ventricular filling pressure and to avoid venodilators. Oxygen is administered via a face mask (100 per cent) and intravenous heparin is administered to prevent any further propagation of thrombi. Thrombolytic agents may be given directly into the pulmonary artery to ensure high concentrations at the appropriate site. Occasionally pulmonary embolectomy may be required. This may be done without cardiopulmonary bypass using caval inflow occlusion and extracting the embolus through a pulmonary arteriotomy. Better results are likely if the patient is fit enough for cardiopulmonary bypass to be established.

Lung transplantation. Lung transplantation is becoming an established therapy for those with end-stage parenchymal or pulmonary vascular disease. The indications for lung trans­plantation are varied and may involve the use of one donor lung, two donor lungs or the heart—lung block. Cystic fibrosis and irreversible pulmonary hypertension with right ventri­cular failure are the main indications for heart—lung trans­plantation but there is now a trend towards single and sequential bilateral lung transplantation, leaving the native heart in situ. This reduces the risk of airway dehiscence which is common with a tracheal anastomosis. Pulmonary fibrosis and obstructive airway disease in young people are indications for single lung transplantation. Donor selection is much the same as for cardiac transplantation except that there must be good respiratory function and no evidence of pulmonary oedema, contusion or infection at the time of harvesting. Matching of donor and recipient and cytomegaloviral (CMV) status is more important than in heart transplantation in trying to avoid the development of CMV pneumonitis.

The recipient operation depends on the nature of the transplant. Heart—lung transplantation requires a median sternotomy and cardiopulmonary bypass. The recipient heart (in the absence of right heart failure) may be suitable for transplantation into another recipient. Single lung transplan­tation is performed through a thoracotomy with cardio­pulmonary bypass if required. Vigorous physiotherapy and judicious antibiotic use are important in the early postoperative period. Opportunist infections may develop secondary to the immunosuppressive drugs and carry a high mortality unless treated aggressively. One-year survival fol­lowing heart—lung, double lung and single lung trans­plantations stands at between 60 and 70 per cent.

There is a current shortage of suitable donors for organ transplantation, therefore alternative treatments for end-stage disease are being explored. One recent development in the field of thoracic surgery is lung volume reduction. This involves excising areas of lung in emphysematous patients with often surprising degrees of subjective and objective improvement. It is unsure whether this procedure restores the mechanics of breathing by altering the chest wall dimensions or improves respiratory function by minimising ventilation—perfusion mismatching.

The diaphragm

The diaphragm is the fibromuscular structure separating the thorax from the abdomen (Fig. 47.34). There are two well-recognised congenital sites where abdominal viscera can herniate into the chest. Traumatic rupture of the diaphragm may also lead to herniation. Congenital hernia tend to be apparent shortly after birth, with over 80 per cent presenting on the left side (Fig. 47.35). There is respiratory distress, apparent dextrocardia, a scaphoid abdomen and radiological appearances of bowel in the hemithorax. Treatment involves urgent nasogastric suction (to prevent distension of the bowel and further compression of the lung) and general resuscitation before surgical repair. Hernias manifesting later in life present with vague dyspeptic symptoms or a feeling of fullness in the chest.

Repair is advised and is undertaken through a left upper transverse abdominal approach or by thoracotomy through the seventh intercostal space with nonabsorbable sutures to repair the defect once the hernia has been reduced.

Oesophageal hiatus hernia is a common problem and is dealt with in Chapter 50.

Hernia through the foramen of Morgagni

This is an anteriorly placed hernia with the defect between the sternal and costal attachments of the diaphragm. The most commonly involved viscus is the transverse colon.

  Hernia through the foramen of Bochdalek

This is really the persistence of the pleuroperitoneal canal and the opening is in the dome of the diaphragm posteriorly. It is the most common diaphragmatic hernia in children and presents with severe respiratory distress. There is a classic triad of respiratory distress, apparent dextrocardia and a scaphoid abdomen.

Eventration of the diaphragm

This is an abnormally elevated position of one or both hemi­diaphragms from paralysis or atrophy of the muscle fibres. There may be some spontaneous improvement if the condi­tion occurs in the perinatal period but long-standing cases with paradoxical respiration may benefit from operation.

The aim of surgery is to fix the diaphragm in inspiration so that paradoxical movement and mediastinal shift are mini­mised. This is achieved by plication of the redundant diaphragm, raking care not to damage the branches of the phrenic nerve.