Sputum and the Airways Flashcards
What are airway defences
Physical mechanisms, airways fluid and mucociliary escalatory, innate and adaptive mechanisms, nasal hair, turbinates and mucociliary transport
What are the physical defense mechanisms
Humidification, particle expulsion (cough/ sneeze), and particle removal: 90& 10um particls removed in nostril/ nasopharynx, 1-2um particles deposited in the lung. Turbulent flow leads to impaction of particles and clearance by mucociliary transport then the cough reflex
Describe airways fluid
Mucus is gelatinous substance consisting mainly of polysaccharides. Relatively impermeable to water. Secreted from goblet/ mucus glands. Cilia contact with this gel layer and coordinate to push the layer continually upwards (mucociliary escalator)
Describe a cilum in cross section
9 outer doblets and 2 central microtubules
What are the two aspects of lung immune defense
Innate and adaptive (acquired)
Describe the lungs innate immunity
Humoral- lactoferrin, lysozymes, defensins, complement. Cellular- alveolar macrophages, induced neutrophils
Describe the lungs adaptive immunity
Humoral- B lympohcytes, plasma cells, immunoglobulin. Cellular- dendritic cells, T lymphocytes
What make up innate immunity
Alveloar macrophages and epithelial cells which make up the innate immunity
What are dendritic cells part of
The acquired immune system
What are dendritic cells
Antigen presenting, they travel into the lymphoid tissue and present the antigen to T cells which triggers the release of TNF alpha and INF-gamma.
What do T helper cells stimulate
B cells which results in complement activation
What does uncontrolled inflammation lead to
A break in the mucociliary transport system which means you can’t remove mucus and therefore get another infection
Describe the inflammation infection cycle
External insult (infectious or toxic) -> ciliary dyskinesia or alterted bronchial dynamics (affected by genetic predisposition)-> ineffective mucus clearance -> chronic or recurrent infection (affected by impaired immune system) -> bronchial wall inflammation and destruction (caused by external insult- infectious or toxic)… cycle repeats
Clinical features of bronchiectasis in adults
Cough- in over 90% of adults, daily sputum production present in over 75%, intermittent sputum preset in 20%, unproductive cough in up to 8%). Breathlessness (83% of adults). Haemoptysis (83% of adults cough up blood). Chest pain (30% of adults). Weight loss/ malaise/ low energy.
When should I suspect bronchiectasis
Adults with a chronic cough, particularly in the presence of any of the following: daily sputum production, pseudomonas aeruginosa in the sputum, a young age at presentation, a history of symptoms over many years, no history of smoking. Adults thought to have chronic obstructive pulmonary disease, who do not smoke, or who have frequent or prolonged exacerbations. Pseudomonas aeruginosa is everywhere, however it is not anatomically normal if it gets into the lungs
What are important common causes of chronic cough which should be considered
Smoking, asthma, chronic obstructive pulmonary disease, drug adverse effects (for example ACE inhibitors), postnasal drip, gastro-oesophageal reflux disease
What are less common but serious causes of chronic cough
Lung cancer, pulmonary fibrosis, tuberculosis, foreign body
What are the signs of bronchiectasis
Coarse crackles (usually in early inspiration, lower lung fields) present in approximately 70%. Wheeze present in 40%. Large airway rhochi in 44%. Finger clubbing occurs infrequently and weight loss
What is the cause of the coarse crackles observed in bronchiectasis
Secretions in the airways moving
Describe the use of x-ray in people with bronchiectasis
Chest x-ray in all people suspected of having bronchiectasis. Abnormal in 90% of people with bronchiectasis. Main value of chest x-ray is to exclude other causes of cough such as lung cancer
What do tram lines show
Bigger airways filled with mucus
Describe the aetiology of cystic fibrosis
Genetic: cystic fibrosis (4%). Post-infective (40%)- this is the most important cause, for example people who had whooping cough as a child. Aspiration (4%). Immune deficiency e.g. CIVD (5%)- common variable immune deficiency means that you have no immune memory. ABPA (7%)- abnormal allergic response to fungi. Ciliary defect: PCD (3%)- cilia don’t neat properly. Connective Tissue Disease: (5%). Idiopathic (32%)
When do you always need to screen for cystic fibrosis
When a person under the age of 40 is diagnosed with bronchiectasis
What do we try to influence in a person with impaired mucociliary clearance
Obstruction, infection and inflammation by trying to decrease the number of those that a person has.
