Lower Respiratory Tract Infections Flashcards
When in the year are LRTIs most common?
Winter
How does incidence of LRTI vary with age?
Very common in small kids
Drops off in kids>5
Then Increases with age
What is happening in Acute bronchitis?
The bronchi are temporarily inflamed
What are the symptoms of Acute acute bronchitis?
Cough Infected Sputum (green/yellow) Wheeze Fever Shortness of Breath
What causes Acute Bronchitis?
An infection of the lungs, 90% of cases its viral
What bacteria are known to cause Acute Bronchitis?
Strep. Pneumoniae
Haemophilus Influenzae
Moraxella Catarrhalis
What part of the lung is affected by Pnuemonia?
The parenchyma, i,e, alveoli
What symptoms come with pneumonia?
Breathlessness Pleuritic chest pain/pluerisy Cough often with infected sputum Fever Sweating/Shivering
How does a CXR look for someone with lobar pneumonia?
Large isolated sections of consolidation
How does a CXR look for someone with bronchopneumonia?
Patchy consolidation all over the lungs
How serious a killer is pneumonia?
The uks 2nd highest killer with a hospital mortality of 6-15%
What is bronchiectasis?
Permanent Abnormal dilatation of the bronchi which allows mucous to build up leading to chronic sepsis
What are some common causes for bronchiectasis?
- Immunoglobulin deficiencies
- Cystic fibrosis
- Following severe infectious episodes like pneumonia and TB
What can bronchiectasis increase susceptibility to?
Frequent lung infections, including recurrent pneumonia
What are the common symptoms of bronchiectasis??
Cough Large scale sputum production Copious pus formed Occasional haemoptysis (couhing blood) Frequent Chest infections
What other signs are there of bronchiectasis?
Clubbing
Lung crackles on both inspirtaiton and expiration
What kind of investigations can be used for bronchiectasis?
- A sputum culture to show up resistant organisms like psuedomonas and klebsiella
- Spirometry to show the level of airflow obstruction caused by the mucous/sepsis
- CXR or CT
What would a CXR of bronchiectasis show?
Possibly nothing
In extreme cases cystic “tramlines” of the enlarged bronchi are visible
What would a CT of bronchiectasis show?
Outlines of dilated bronchi
What is the main diagnostic test for bronchiectasis?
A high resolution CT
How does an empyema form?
- Fluid collects between pleura during pneumonia
- Microorganisms can inefct this fluid leading to pus formation and empyema
How do we distinguish between pleural effusion and empyema?
The fluid is collected with a needle and examined
How are pleural effusion and empyema treated?
An empyema must be drained completely, sometimes surgically, otherwise the infection persists.
A pleural effusion need only be drained if theres symptoms or it wont resolve.
Why catn antibiotics treat an empyema?
They dont penetrate the pleural cavity well
How does a lung abscess form?
During pneumonia pulmonary tissue necrosis occurs a pocket of infected fluid/debris forms
How do we confirm a lung abscess diagnosis?
Chest CT.
A CXR can see them but not sufficiently for diagnosis.
When does a lung abscess tend to occur?
In aspiration pneumonia. Alcoholism is the most common predisposing condition to lung abscesses
How is a lung abscess treated?
With long-term antibiotics or sometimes drainage
What are the 3 “levels” of microorgansism pathogenicity?
- Primary
- Facultative
- Opportunistic
What 3 factors feed into a lung infection?
- Microorganism pathogenicity
- Capacity to resist infection (host defences and age)
- Exposure to infection
What are the 5 categories of host defence to lung infection?
- Mucocilliary escalator
- Alveolar macrophages
- Respiratory tract secretion
- General immune system
- Upper respiratory tract defences
What do alveolar macrophages do to defend the lungs?
They phagocytose and digest any little foreign particle fucker that gets into the alveoli
How does the mucocilliary escalator work?
macrophage ingests something undigestible
Hops onto mucous
Swept up by cilia (along with any foreign particles stuck in the mucous)
Swallowed (clearing throat) or coughed up
How is the escalator damaged?
A viral infection can damage the ciliary epithelium preventing it from working and allowing infection ot take root.
What do respiratory tract secretions do?
Help the mucocilliary escalator work
Contain important anti-bacterial compounds
How does the upper respiratory tract protect us?
- The nose filters large particles
- particles stick to mucous and are swept away by cilia
- Warms and humidifies air which is imporattn to escalator function
What are the 6 aetiological classes of pneumonia?
- Community acquired (CAP)
- Hospital acquired (Nosocomial)
- Pneumonia in the Immunocompromised
- Atypical
- Aspiration pneumonia
- Recurrent pneumonia
What causes consolidation on a pneumonia CXR?
Inflamed bronchioles and alveoli fill with suppurative exudate
What are hte possible end points for pneumonia?
- Most resolve
- PLeursy/pleural effusion/empyema
- Organistion & Scarring
- Lung abscess
- Bronchiecstasis
What types of organistion can occur after pneumonia?
A mass lesion
Constrictive bronchiolitis
Cryptogenic organising pneumonia (COP)
Name some microorganisms commonly causing LRTIs:
Strep Pneumoniae Haemophilus Influenzae Klebsiella Pseuodomonas Staph Aureus
What causes recurrent pneumonia?
Failure of the bodies defences due to:
- Local bronchial obstruction (tumour,forien body etc)
- Local pulmonary damage (e.g. bronchiecstasis)
- Generalised lung disease (Cystic fibrosis, COPD)
- Non-resp. disease (Aspiration, immunocompromised etc)
What are the biggest causative organisms for community acquired pneumonia?
Strep Pneumoniae
Staph Aureus
What are the bigest causative organisms for noscomial pneumonia?
Gram -ves
Staph Aureus
Name some ways aspirating fluid is caused?
- Vomiting
- Oesophageal lesion
- Obstetric anaesthesia
- Neuromuscular disorders
- Sedation
What is hypostatic pneumonia?
Pneumonia caused by a build up of fluid in the lungs dorsal region. particularly in people bedridden.
