The predominant symptom in respiratory medicine is that of breathlessness. The degree of disability produced by breathlessness can be assessed before and after treatment by asking the patient to walk for 6 min along a measured track. This has been shown to be a reproducible and useful test once the patient has undergone an initial training walk to overcome the learning effect. Increasing emphasis is being placed on exercise tests incorporating assessment of both lung and heart function in the investigation of breathlessness. Such tests involve the use of sophisticated .equipment enabling measurement of uptake of oxygen (V02), work performed, heart rate and blood pressure together with serial ECGs. Correlation of these variables allows:
• The early detection of lung disease
• The detection of myocardial ischaemia
• The distinction between lung and heart disease
• Assessment of fitness
Diagnostic aspiration is necessary for all but very small effusions. A needle attached to a 20 ml syringe is inserted through an intercostal space over an area of dullness. Fluid is withdrawn and the presence of any blood is noted. Samples are sent for protein estimation, cytology and bacteriological examination, including culture and Ziehl-Nielsen stain for tuberculosis. Large amounts of fluid can be aspirated through a large needle to help relieve extreme breathlessness. Because of the risk of introducing infection into the pleural space with the subsequent development of an empyema this technique must be performed using full aseptic precautions.
Pleural aspiration, drainage and biopsy are being increasingly performed under ultrasound guidance or following X-ray localization of the fluid.
Experienced operators obtain tissue in nearly all patients and, provided multiple specimens are taken, positive results may be expected in up to 80% of cases of tuberculosis and in 60% of cases of malignancy. The technique is illustrated in Fig. 12.17. If tissue is not obtained by blind pleural biopsy, the pleura can be examined by fibreoptic thoracoscopy and any lesions biopsied, yielding further results in a further 80%. Pleural drainage This is carried out when large effusions are present producing severe breathlessness or for drainage of an empyema .
Pleurodesis is performed for recurrent/malignant effusion.
Mediastinoscopy and scalene node biopsy
This technique is used increasingly in the management of carcinoma of the bronchus. It involves inspection of the mediastinal structures using a mediastinoscope inserted by blunt dissection downwards from behind the proximal end of the clavicle. Subsequent biopsy of tissue will reveal the presence or absence of malignant cells in enlarged lymph nodes previously detected by CT, allowing accurate staging of the disease.
Central bronchial lesions can be biopsied readily. Washings can be talcen from lobes containing more peripheral lesions for cytological examination for malignant cells, and appropriate staining and culture for bacteria including Mycobacterium and Pneumocystis carinii. Diffuse parenchymal lung disease can be investigated using transbronchial biopsy. The biopsy forceps are pushed as far as possible to the periphery of the lung, the patient is asked to breathe in, and the jaws of the forceps are closed, removing a small piece of peripheral airway and surrounding lung parenchyma. Biplanar screening allows isolated peripheral lesions to be biopsied in the same way. A histological diagnosis can be made in 95% of central lung cancers but in only 50-75% of peripheral lesions biopsied during fibreoptic bronchoscopy. Peripheral lesions are best biopsied percutaneously using a fine needle under direct X-ray or CT control.
This technique can be used both in patients who have disease confined to one lobe and in those with more diffuse lung disease. The tip of the fibreoptic bronchoscope is lodged in the segmental orifice and 20 ml of 0.9% sterile saline is squirted down the suction port of the bronchoscope and immediately aspirated. This is repeated five times; about 40-60% of the total volume is recovered. Fluid is strained through two layers of surgical gauze and the volume is noted. The cells are then spun down and resuspended at a concentration of 1 x 107 cells/rnl for differential counting. Since there is a considerable overlap in the distribution of cells seen in bronchoalveolar wash specimens in different diseases, this technique has no value in diagnosis. However, it can be used to monitor progression of disease, since improvement is characterized by a reduction in the number of cells and a return towards the normal proportions of different cell types. This enables the direct visualization of the bronchial tree as far as the subsegmental bronchi under a local anaesthetic.
Lesions requiring biopsy seen on chest X-ray
Stridor Positive sputum cytology for malignant cells with no chest X-ray a normality Collection of bronchial secretions for bacteriology, especially tuberculosis Recurrent laryngeal nerve paralysis of unknown aetiology Infiltrative lung disease (to obtain a transbronchial biopsy) Investigation of collapsed lobes or segments and aspiration of mucus plugs.
The patient is starved overnight
Atropine 0.6 mg i.m. is given 30 min before the procedure Topical anaesthesia (lignocaine 2% gel) is applied to the nose, nasopharynx and pharynx Intravenous sedation (e.g. diazepam 10 mg or midazolam 2.5-10 mg) may be needed The bronchoscope is passed through the nose, nasopharynx and pharynx under direct vision to minimize trauma Lignocaine (2 ml of 4%) is dropped through the instrument onto the vocal cords The bronchoscope is passed through the cords into the trachea All segmental and subsegmental orifices should be identified Biopsies and brushings should be taken of macroscopic abnormaliies or occasionally from peripheral lesions under radiographic control
All patients require sedation to tolerate the procedure Minor and transient cardiac dysrhythmias occur in up to 40% of patients on passage of the bronchoscope through the larynx Oxygen supplementation is required in patients with p.02 below 8 kPa Fibreoptic bronchoscopy should be performed with care in the very sick and transbronchial biopsies avoided in ventilated patients due to increased risk of pneumothorax Massive bleeding may occur on accidental biopsy of vascular lesions or carcinoid tumours. Rigid bronchoscopy may be required to allow adequate accessto bleeding point and haemostasis
The tip of a fine needle is placed through a drop of allergen solution on the volar surface of the forearm into the epidermis, which is gently pricked with an upward lifting motion. A separate needle should be used for each allergen. If the patient is sensitive to the allergen, a weal develops and the diameter of the induration (not the erythema) should be measured after 15 min. A weal of at least 2 mm diameter and greater than the reaction to the control solution is a positive test. The results should be interpreted in the light of the history. Skin tests can be inhibited by concurrent administration of antihistamines, so these should be stopped 48 hours before testing. They are not inhibited by bronchodilators or corticosteroids.