Lower respiratory disease Flashcards
What are the 4 causes of pneumonia?
Community acquired
Hospital acquired
Ventilator acquired
Aspiration
What are some predisposing factors to LRTI?
Loss or suppression of cough reflex / swallow
- e.g. stroke, coma, ventilation
Ciliary defects e.g. PCD
Mucus disorders e.g. CF
Pulmonary oedema – fluid flooding alveoli
Immunodeficiency: congenital or acquired
Macrophage function inhibition e.g. smoking
What are some bacteria that cause LRTIs?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Staphylococcus aureus
- Klebsiella pneumonia
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- Legionella pneumophila
- Mycobacterium tuberculosis
What are some viruses that cause LRTIs?
- Influenza
- Parainfluenza
- Respiratory syncytial virus
- Adenovirus
What are some fungi that cause LRTIs?
- Aspergillus sp.
- Candida sp.
- Pneumocystitis jiroveci
What are the different syndromes of LRTI?
bronchitis, bronchiolitis, pneumonia
What is acute bronchitis?
Inflammation & oedema of trachea and bronchi
Cough (typically dry), dyspnoea & tachypnoea
Cough may be associated with retrosternal pain
What are the causes of bronchitis?
Viruses are the usual cause (rhinovirus, coronavirus, adenovirus, influenza)
Bacterial causes less common (H.influenzae, M.pneumoniae, B.pertussis)
How is acute bronchitis diagnosed?
Diagnostic tests not indicated in mild presentations
Vaccination & previous exposure history (e.g. influenza, B. pertussis) may exclude some organisms
If needed, cultures of respiratory secretions may be helpful if looking for a specific cause, e.g. B. pertussis – but not routine
How is acute bronchitis treated?
Supportive treatment for healthy patients
Those with severe disease or co-morbidities may require oxygen therapy or respiratory support
Antibiotics only if bacterial cause is suspected or found
What is chronic bronchitis and who does it generally affect?
Cough productive of sputum on most days during at least 3 months of 2 successive years (which cannot be attributed to an alternative cause)
Affects 10-25% of adult population
Most common in men and >40yrs
Associated with smoking, pollution, allergens
What is the pathology behind chronic bronchitis?
Inflammation & oedema of airways is mediated by exogenous irritants (rather than infective agents)
Patients have acute exacerbations mediated by same infective pathogens as acute bronchitis
If airflow obstruction present on spirometry = COPD
What is bronchiolitis and hat are the symptoms?
Inflammation and oedema of bronchioles
Acute onset wheeze, cough, nasal discharge, respiratory distress (grunting, retractions, nasal flaring)
Who does bronchiolitis typically affect?
Peaks in winter and early spring, in infants 2-10 months
Most commonly caused by RSV (75% of cases)
- 80% children have evidence of previous RSV infection by 2yrs old
(Also caused by parainfluenza, adenovirus, influenza)
How is bronchiolitis diagnosed?
Chest x-ray
Full blood count
Microbiological diagnosis: usually nasopharyngeal aspirate of respiratory secretions sent for viral PCR
How is bronchiolitis treated?
Supportive: oxygen, feeding assistance
No clear evidence to support steroids, bronchodilators, ribavirin
Antibiotics only if complicated by bacterial infection
What is pneumonia?
Infection affecting the most distal airways and alveoli
Formation of inflammatory exudate
What are the two anatomical patterns of pneumonia?
Bronchopneumonia and Lobar pneumonia
What are the features of bronchopneumonia?
Characteristic patchy distribution centred on inflamed bronchioles & bronchi then subsequent spread to surrounding alveoli
What are the features of lobar pneumonia?
Affects a large part, or the entirety of a lobe
90% due to S.pneumoniae
How do you define hospital acquired pneumonia (HAP)?
Pneumonia developing >48hrs after hospital admission
Different causative organisms to CAP, especially if >5days after admission: enterobacteriaceae & Pseudomonas sp.
How do you define ventilator acquired pneumonia (VAP)?
Subgroup of HAP
Pneumonia developing >48hrs after ET intubation & ventilation
How do you define aspiration pneumonia?
Subgroup of HAP
Pneumonia resulting for the abnormal entry of fluids e.g. food, drinks, stomach contents, etc. into the lower respiratory tract
Patient usually has impaired swallow mechanism
What is the epidemiology of CAP?
Incidence of 1 per 100 people per year (common!)
20-40% cases require hospital admission
Peak age 50-70 years
Peak onset midwinter to early spring
Acquisition of organisms:
- Person-to-person or from a person’s existing commensals (S.pneumoniae, H.influenzae)
- From the environment (L. pneumophilia)
- From animals (C.psittaci)
