Bronchiectasis
From Pharmpedia
Bronchiectasis is a chronic, abnormal dilation of airways (bronchi or bronchioles) as a sequel to inflammation or obstruction.
It can be considered as a chronic obstructive pulmonary disease (COPD)* where there is airway inflammation, persistent or intermittent obstruction, depressed mucus clearance, excess and thick sputum production. The disease may be congenital or acquired. The congenital form is rare and seen in infants or children, usually due a developmental anomaly of the respiratory tract or functional defects.
The acquired form is more common and is usually seen in adults or older children and is usually due to an infectious cause.
- COPD is now the preferred term for patients with airflow obstruction who were previously diagnosed as having chronic bronchitis or emphysema.
Contents |
Incidence
The exact incidence of bronchiectasis is not known. However its incidence has considerably declined after the antibiotics era and due to universal immunization.
The mean age at onset of symptoms is 39 years, and the age range with the highest frequency of bronchiectasis is 60 to 80 years. It appears to be more common in women and surprisingly in non-smokers.
Causes
Infection (Klebsiella, Mycobacterium tuberculosis, Mycobacterium avium complex [MAC], Staphylococcus aureus, Mycoplasma, Bordetella pertussis, Pseudomonas aeruginosa, measles, influenza, rubeola, herpes simplex, respiratory syncytial virus [RSV], adenovirus, HIV, histoplasmosis, coccidioidomycosis)
Congenital
Cystic fibrosis
Alpha1-antitrypsin deficiency
Primary ciliary dyskinesia
Kartagener's syndrome (situs inversus, sinusitis, and bronchiectasis)
Immunodeficiency states (hypogammaglobulinemia)
Young's syndrome (azoospermia and chronic sinopulmonary infections)
Yellow-nail syndrome (lymphedema, pleural effusions, hypertrophic nails)
Bronchial cartilage deficiency (Williams-Campbell syndrome)
(the list is not complete)
Airway obstruction
Foreign body aspiration
Bronchial stricture
Tumors (Bronchogenic carcinoma, bronchial adenoma)
External compression of bronchus (Mediastinal mass or lymph node, Lung cancer, aneurysm)
Miscellaneous
Collagen vascular diseases
Autoimmune diseases (e.g. rheumatoid arthritis, Sjögren syndrome, Behçet's syndrome, ulcerative colitis, Crohn’s disease)
Hypersensitivity (Allergic bronchopulmonary aspergillosis)
Radiation injury
Toxic gas inhalation injury (smoke, sulfur dioxide, ammonia)
Recurrent gastric aspiration
Symptoms and signs
The most common symptom is daily productive cough (sputum often in large quantities).
Majority also have wheeze and shortness of breath.
One third suffer from chronic sinusitis
Recurrent fever may occur in some.
Symptoms often begin after a respiratory infection, and worsen over a period of years.
Less commonly hemoptysis (bloody cough) Pleuritic chest pain
Other additional symptoms depend on associated conditions (e.g. bloody diarrhea in ulcerative colitis, joint pain (rheumatoid arthritis), infertility (in men) etc.
Occasionally, a patient may be asymptomatic.
Physical findings are nonspecific.
Decreased breath sounds, prolonged expiration, wheezing, increased use of accessory muscles of respiration, clubbing of fingers are the usual signs. There may be anemia, Raised jugular venous pressure, weight loss and ankle swelling.
Diagnosis
Diagnosis of bronchiectasis usually depends on the history and imaging study of the chest. With the triad of chronic cough, sputum production, and hemoptysis first think of bronchiectasis. In very chronic cases, the collected sputum may separate into three layers: frothy at the top, greenish and turbid in the middle, and thick with pus at the bottom.
X-ray chest is abnormal in majority of patients (findings include increased bronchovascular markings, dilated bronchi due to peribronchial inflammation and fibrosis ("tram tracking"), crowding, cystic air-fluid filled spaces, honeycombing and infiltrates).
High-resolution CT scanning (HRCT) of the chest is presently the "gold standard" to provide accurate information about the severity and extent of bronchiectasis.
Bronchography is not nowadays performed, though prior to HRCT it was considered as best. But it may be needed for precise anatomic definition prior to surgery.
Bronchoscopy may be useful to rule out focal bronchial lesions, remove foreign bodies, sometimes to control bleeding and for a precise pathologic diagnosis.
Pulmonary function tests are nonspecific and have limited diagnostic value, but done to study the extent of obstruction. The ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) is <0.7. FVC is less than 80% of the predicted value, indicating restrictive defect. These tests help in assessing the response to treatment.
Sputum cultures may be necessary to identify the pathogen and guide the choice of antibiotic.
Additional tests may be needed to rule out a systemic process, like
- Sweat chloride test (Cystic fibrosis)
- Serum immunoglobulins (hypogammaglobinemia)
- Ciliary ultrastructure examination
Differential diagnosis
Bronchial asthma and pneumonia are the two major disease conditions that may often be mistaken for bronchiectasis leading to inappropriate treatment. Other conditions that may mimic bronchiectasis include chronic bronchitis, pneumonia, mycobacterial and fungal infections.
Pathophysiology
The pathogenesis of bronchiectasis is related to three basic mechanisms: infection, obstruction (both leading to inflammation), and congenital anomaly.
Infection may be due to viral, bacterial or fungal pathogens and usually is of chronic type. Obstruction may be due to tumor, foreign bodies, external compression, bronchial webs, atresia or aneurysm.
Bronchial wall damage may be due to release of microbial toxins (bacterial endotoxins, proteolytic enzymes) and due to inflammatory cytokines (IL-1, IL-8, and TNF-alpha etc) released by the body defense cells and antigen-antibody complexes. Further the system that protects the respiratory tree from such damages may also be broken down (alpha1-antitrypsin may be proteolytically or oxidatively cleaved). This is a perpetuating, cyclical process i.e. with each insult (like repeated infection) the damage is more. Nitric oxide, which affects the immune response, cell signaling, and plasma exudation at inflammatory sites is believed to perpetuate the process.
Obstruction, congenital/hereditary abnormalities, immunologic deficiencies (AIDS); all increase the host susceptibility to infection and/or impair respiratory defenses.
The congenital form is rare and there is abnormality in cartilage formation or impaired mucociliary clearance (cystic fibrosis).
Chronic inflammation leads to extensive inflammatory destruction of bronchial walls, with increased mucus production, and impaired ciliary activity. The adjacent interstitium and alveoli are destroyed with attendant fibrosis and volume loss. All these result in reduced lung volume, airflow, ventilation/perfusion mismatch, hypoxemia, right to left shunts ultimately leading to pulmonary hypertension and cor-pulmonale.
Bronchiectasis is generally associated with chronic bronchitis and/or emphysema.
The resultant anatomic changes have been classified into three categories: cylindrical (diffuse dilatation of the bronchial wall), varicose (dilatation is greater with and constrictions and sacculations), and cystic (saccular- ballooning of the bronchi with fluid-filled, sac-like dilatation) types; all or any of these can be present in a given patient. Bronchiectasis may be unilateral or bilateral but is most common in the lower lobes.
Prevention
Awareness and early identification of conditions associated with bronchiectasis, with early intervention may prevent the development or reduce the severity.
Early detection of and intervention/counseling of congenital anomalies, immunologic deficiencies, tumor, foreign body.
Regular immunization
Avoidance of exposure to respiratory irritants Prompt treatment of infections with appropriate antimicrobials.
Prophylactic or suppressive antimicrobial regimens.
Treatment
Medical: Treatment should focus on symptomatic relief, prevention of complications and if possible the underlying cause.
General measures include
Quitting smoking and avoidance of passive smoking
Pulmonary rehabilitation (to optimize the patient's physical and social performance through improved exercise capacity and health status) Good nutrition (advice from a dietitian)
Prophylactic immunization against pneumococcal pneumonia and influenza (annual); and for measles and pertussis especially in children (however the later two are taken care of under Universal Immunization Program). Patients with severe disease or acute exacerbations usually need hospitalization and may need oxygen and parenteral antimicrobials.
Drug treatment encompasses,
- Antimicrobials: Antibiotics play a vital role in the management of bronchiectasis. Depending upon the severity and type of organism the drug and the route has to be chosen. It is better to choose a broad spectrum agent (to cover gram +ive and –ive)
In general those with mild to moderate disease may be managed as outpatients with azithromycin or tetracycline or co-trimoxazole or cephalosporin (2nd generation) or amoxicillin or a quinolone. The chosen drug is given orally for 7-10 days.
If the condition is severe, parenteral antimicrobials like aminoglycoside (tobramycin or gentamycin) or 3rd generation cephalosporin or fluoroquinolone or a combination of penicillin with aminoglycoside may have to be administered. For other infectious conditions like TB, or atypical mycobacterial infection or HIV appropriate drugs with sufficient duration need to be given. Patients with chronic bronchitis need regular antibiotics. To prevent resistance it is better to administer antibiotics on a regular but intermittent basis with alternating drugs, with at least a week of drug free interval in a month.
- Bronchodilators : Patients with hyperactive airways and wheeze may be prescribed nebulized bronchodilators (salbutamol) as that for bronchial asthma.
- Antiinflammatory agents : Again these agents may be useful if there is evidence of hyperactive airways. Generally inhaled corticosteroids (beclomethasone) or in severe cases short term systemic corticosteroids (prednisolone) may be given.
- Mucolytics : Adequate intake of fluids will keep the sputum thin. Mucolytics may be administered to liquify viscid sputum, for easy expulsion. Simple salt solution or acetyl cysteine or rDNAse (recombinant DNAse) may be nebulized. Further other measures like postural drainage, percussive devices and respiratory physiotherapy may be cheaper, safer, as well as effective.
Surgical
In selected cases, surgical removal of the diseased bronchiectatic portion of the lung (Lobar resection) may be attempted. This is especially useful in advanced cases; in the settings like, localized disease, presence of foreign body or tumor or massive hemoptysis (to control bleeding). In extreme cases bilateral lung transplantation may be needed.
Diet requirements
No special diet is recommended. However since these patients are usually wasted good nutrition should be provided and advice from a dietitian should be sought.
Prognosis
In general the prognosis is good, mainly because of the availability of excellent antibiotics provided patients comply with treatment regimens and practice routine preventive strategies. The quality of life may often be compromised by frequent exacerbations due to infections, progressive respiratory failure due to progression of the disease and attendant sequelae like Cor pulmonale. However the prognosis also depends on the extent, severity and the underlying cause. For example the prognosis may be worse if the underlying cause is a malignant tumor.
Recent Developments
For management of respiratory infections, nebulized antibiotics (e.g. tobramycin- cystic fibrosis patients infected with Pseudomonas tend to respond) are currently tested because of the advantages like, achievement of higher local (lungs) drug concentration with less systemic side effects.
References
-
- Emmons EE and Ouellette D. Bronchiectasis.
- Bronchiectasis-British Lung Foundation
- Bronchiectasis- MercK
- Galvin JR and D'Alessandro MP. Electric Diffuse Lung: The Diagnosis of Diffuse Lung Disease: Bronchiectasis
- Mysliwiec V and Pina JS. Bronchiectasis: the 'other' obstructive lung: an illustrative case report and telltale clinical features. Postgrad Med 1999;106(1):123-31
Author
This is original article by Dr.Gurusamy Sivagnanam
Retrieved from "http://www.pharmpedia.com/Bronchiectasis"
This page has been accessed 813 times. This page was last modified 06:17, 17 March 2006. All content, except where otherwise noted, is licensed under a Creative Commons Attribution License.
