The Respiratory System and Dental Practice

The respiratory system is always affected to some extent by smoking, and enquiry should always be made with regard to smoking habits. Cough is a non-specific reaction to irritation anywhere from the pharynx to the lungs. It may produce sputum or be non-productive. Haemoptysis (coughing up of blood) may occur, and it is important to differentiate this from haematemesis (vomiting of blood). Large volumes of blood may be coughed up in lung cancer, bronchiectasis and tuberculosis. Lesser amounts may be observed in pneumonia and pulmonary embolism. A summary of specific points to obtain in the history is given in Table 3.1, and these are discussed further below.

Relevant Points in the History

Infections of the respiratory tract may be acute or chronic and may be of the upper (i.e. vocal cords or above) or lower tract. Infections of either are a contraindication to GA, which should be deferred until resolution has occurred. An upper respiratory tract infection (URTI) will readily progress to the lower tract if a GA is given. URTIs may occur as part of the common cold, as pharyngitis or tonsillitis and as a laryngotracheitis. The latter in children may cause stridor (‘croup’). The paranasal air sinuses may become infected secondary to a viral URTI (a viral cause being most common). In acute sinusitis, the most commonly implicated bacteria are Streptococcus pneumoniae and Haemophilus influenzae. In maxillary sinusitis (which may also occur secondary to periapical infection of intimately related teeth), pain in the cheek and/or upper teeth is worsened by lowering the head, and there is a mucopurulent nasal discharge. The maxilla over the antrum is tender to palpation. An occipitomental radiograph may show increased radiopacity of the antrum, but this can often be difficult to assess objectively and may be due to a thickened mucosal lining rather than acute infection (Fig. 3.1). Analgesics and antibiotics, e.g. amoxicillin, erythromycin or doxycycline, for 2  weeks may be required. In chronic sinusitis, formal drainage of the antrum may be required. Lower respiratory tract infections are often viral, but bacterial infection will frequently supervene. There are signs of systemic upset, e.g. fever, pleuritic pain (sharp pain on inspiration), cough, green/yellow sputum and possibly haemoptysis. The patient (especially the elderly) may appear confused, and indeed this may be the only sign that something is wrong. There will often be dyspnoea (the subjective feeling of a shortage of breath). Primary pneumonia occurs in previously healthy individuals and is often due to pneumococci or ‘atypical’ organisms. Secondary pneumonias occur in patients with impaired defences, e.g. in malignancy or chronic obstructive pulmonary disease (COPD) such as chronic bronchitis and emphysema. Atypical pneumonias include Legionella pneumophila and Pneumocystis carinii (jiroveci) (a protozoan-like cyst) in AIDS.  The former organism causes Legionnaires’ disease, and the organism

Increased radiopacity of the left maxillary antrum in maxillary sinusitis 

multiplies in stagnant water found in air conditioning systems. It has been isolated from dental units which have been unused over a prolonged period, e.g. weekends or holidays [1]. Units such as this should be ‘run through’ thoroughly before resuming clinical use. An inadequately treated pneumonia may lead to a lung abscess. Aspiration of a foreign body from the mouth can also be a cause. In dentistry this may occur when a rubber dam is not used when it is indicated leading to inhalation of debris or if an inadequate throat pack or uncuffed endotracheal tube is used for dental procedures under GA. The commonest infecting organisms are Staphylococcus aureus or Klebsiella pneumoniae. Bronchial asthma is a generalised airway obstruction which in the early stages is paroxysmal and reversible. The obstruction, leading to wheezing, is due to bronchial muscle contraction, mucosal swelling and increased mucus production. Exposure to allergens and/or stress can induce an attack. It is now accepted that inflammation is an important aetiological factor in asthma and this has resulted in the use of antiinflammatory medication in the management of the condition [2, 3]. In terms of management, infrequent attacks can be managed by salbutamol (Ventolin) inhalers as needed or prophylactically if an attack might be predicted, e.g. before exercise or prior to a stressful event such as dental treatment. If the attacks are more frequent, the salbutamol should be used regularly. If this is insufficient, inhaled steroids (or cromoglycate in the young) should be used. In severe cases systemic steroids may be prescribed. Enquiry should be directed toward the efficacy of medication, use of steroids and whether there have been episodes of hospitalisation.

COPD comprises chronic bronchitis and emphysema. Chronic bronchitis is said to exist when there is sputum production on most days for 3 months of the year in 2 successive years. Emphysema is dilatation of airspaces distal to the terminal bronchioles by destruction of their walls. The two coexist in varying proportions in COPD and smoking is a common predisposing factor [4]. Emphysema may rarely be inherited and is then due to alpha-1-antitrypsin deficiency. Some COPD patients are breathless but not cyanosed (‘pink puffers’); some are cyanotic and if heart failure supervenes become oedematous or bloated (‘blue bloaters’). In these patients the respiratory centres are relatively insensitive to carbon dioxide, and they rely on ‘hypoxic drive’ to maintain respiratory effort. It is dangerous to give high levels of supplemental oxygen for longer than brief periods to these patients as breathing may stop or the patient may begin to hypoventilate. Treatment of acute exacerbations of COPD involves broad-spectrum antibiotics, bronchodilators (inhaled or nebulised) and possibly physiotherapy. Steroids may also be used. Dental treatment should be avoided during an exacerbation and in any event if possible should be carried out under LA. Tuberculosis caused mainly by Mycobacterium tuberculosis is a disease that has increased in prevalence in recent years, largely due to the immunocompromised HIV population, in the malnourished, e.g. the materially deprived and in immigrants from underdeveloped countries. It is unlikely to be a great risk to dental staff unless the patient has an active pulmonary type in which case dental treatment is better deferred until control has been achieved. Pulmonary TB is usually spread by inhaling infected sputum and is highly infectious when active. If delayed treatment is not possible, aerosols should be reduced to a minimum, and it may be useful to carry out treatment under rubber dam. Masks and spectacles are mandatory for all personnel. Most primary infections are subclinical. Haematogenous spread can lead to skeletal or genitourinary lesions. Widespread lesions give rise to the term ‘miliary TB’. A diagnosis of TB is suggested by chronic cough, haemoptysis, fever, night sweats and weight loss. Confirmatory tests include chest X-ray, sputum examination for acid and alcohol fast bacilli and the skin test or Mantoux test which shows a delayed hypersensitivity to a protein derived from Mycobacterium tuberculosis. Specific chemotherapy is by far the most important measure in the treatment of TB. In the UK, rifampicin, isoniazid, ethambutol, streptomycin and pyrazinamide are considered in the first-line treatment of TB. The majority of patients are treated as outpatients, whereas a policy of ‘isolation’ was followed in the past. Immobilisation of the patient is necessary in some forms of skeletal TB. Bronchiectasis is a condition where the bronchi are irreversibly dilated and act as stagnation areas for persistently infected mucus. It should be suspected in any persistent or recurrent chest infection. It may be congenital, e.g. in cystic fibrosis or postinfection, e.g. TB and measles. Haemoptysis may occur. Intensive physiotherapy, antibiotics and bronchodilators are the mainstays of treatment. Cystic fibrosis is one of the commonest inherited diseases (1 in 2000 live births) and is autosomal recessive. The cells are relatively impermeable to chloride (hence diagnosis by measuring the chloride concentration of sweat), and thus salt-rich secretions are produced. The mucus is viscid and blocks glands. In the young adult 3 The Respiratory System and Dental Practice 31 or child, recurrent chest infections are seen; bronchiectasis and pancreatic insufficiency also occur. Lung cancer is usually linked to cigarette smoking and may present in various ways including cough and haemoptysis. The disease may produce cerebral and hepatic metastases. The latter produce hepatomegaly, jaundice or ascites (fluid in the abdomen producing distension). Bone metastases (including the facial bones) may lead to pathological fracture. If the superior vena cava becomes compressed by tumour, facial oedema and cyanosis may occur (the superior vena cava syndrome). These patients may have muscle weakness (the Eaton-Lambert syndrome) in which unlike myasthenia gravis the use of muscles leads to better function rather than deterioration. Ectopic hormone production may occur in lung cancer (commonly adrenocorticotrophic hormone—ACTH). Occupational lung disease is still seen in patients and may lead to significant respiratory impairment. Most inhaled particles cause no damage as they become trapped in the nose or are removed by the mucociliary clearance system. Particles may be destroyed by alveolar macrophages. The pneumoconioses are conditions which result from inhalation of various dusts and include asbestosis, silicosis and coal workers’ pneumoconiosis. They will all restrict respiratory efficiency to some degree and potentially have a bearing on dental treatment provision. Sarcoidosis is a multisystem disorder of unknown aetiology and is characterised by non-caseating granulomata. It most commonly affects the lungs of young adults but may occur at any age. Thoracic sarcoidosis classically presents incidentally as bilateral hilar lymphadenopathy on chest X-ray and is often asymptomatic. It may, however, be associated with cough, fever, arthralgia, malaise or erythema nodosum. Erythema nodosum comprises painful, erythematous nodular lesions on the anterior shins but is not specific for sarcoid, for example, they may also be seen in TB. Extra-thoracic manifestations of sarcoidosis are listed in Table 3.2. Gingival swelling found to be due to sarcoid is shown in Fig. 3.2. The mainstay of diagnosis is a rise in serum angiotensinconverting enzyme level. Treatment may be carried out using steroids which may have implications for dental treatment as well as potential respiratory impairment. The adult respiratory distress syndrome (ARDS) is a progressive respiratory insufficiency which usually follows a major systemic insult, e.g. trauma and infection, and is largely due to interstitial pulmonary oedema arising from leaking capillaries. It is only relevant to mainstream dental practice in that about one third of surviving patients may be left with pulmonary fibrosis. Other causes of pulmonary