LRTI I Flashcards
Bronchitis epidemiology
Characterised by emporary (self-limited) inflammation of the large and mid-sized bronchial tubes.
There is season variation with the peak incidence in winter, and where influenza (outbreak?) is present in the community.
Risk factors for bronchitis
- Age (children <5 years of age; and the elderly)
- Underlying disease (ie. chronic obstructive pulmonary disease [COPD], asthma(
- Exposure to second hand smoke
Bronchitis microbiology
Viral
- Influenza virus
- Rhinovirus
- Adenovirus
- Respiratory synctial virus (RSV)
- Parainfluenza virus
- Human metapneumovirus
Bacterial (10% of cases)
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- *Bordatella pertussis *(rare cases)
Pathophysiology of bronchitis
A virus(es) replicating in the epithelial cells of the upper respiratory tract can spread to the lower airways resulting in:
- Inflammation of the bronchial/bronchiolar epithelia (ie. infiltartion of mononuclear cells)
Necrotic epithelia sloughed off into the lumina of the airways, together with inflammation and increase mucus production and oedema, can cause obstruction characterised by ‘wheezing’
Clinical manifestations of bronchitis
Symptoms usually begin with common cold syndrome:
- Nasal congestion, rhinitis, sore throat and general malaise
- Low grade fever (37.5-38)
- Cough (dry at first/becomes productive [white; green; yellow sputum])
- Wheezing
- Symptoms and signs usually resolve over 7-10 days for otherwise healthy person
Bronchitis diagnosis
Made on clinical presentation; suspected in any person with acute respiratory illness where cough is the dominant symptom.
Bronchitis differential diagnosis
Pertussis (whooping cough)
Pneumonia (ie CXR with signs of infiltrates/consolidation)
Chronic obstructive pulmonary disease (COPD); asthma
Bronchitis treatment
Supportive therapy: adequate hydration; cough suppressants; decongestants; antihistamines
Bronchiolitis epidemiology
Described inflammation of the smaller air passages, bronchioles of the lung.
Season occurence: peak incidence is during winter to early spring; usually correlates with the prevalence of RSV in the community.
More common during the first year of life
- Each year 1-3% of infants <12 months are hospitalised with bronchiolitis, in 80% of these cases the infants are <6 months of age
- More common in boys
- Children with chronic underlying conditions (i.e. cardiopulmonary function decline)
Bronchiolitis risk factors
- Young maternal age
- Lower cord blood antibody titres to RSV
- Lower socioeconomic status
- Crowded living conditions
- Bottle feeding
- Tobacco-smoke exposure
Bronchiolitis microbiology
Virus
- RSV
- Rhinovirus
- Influenza
- Parainfluenza
- Adenovirus
- Bocavirus
- Non-SARS coronaviruses
Bronchiolitis clinical manifestations
Prodrome (range 2-7 days) of signs of URTI
- Coryza
- Cough
- Fever (usually mild)
Followed by:
- Wheezing
- Dyspnoea
- Dehydration (due to coughing spasm associated vomiting/poor oral intake)
- Recovery usually over a period of 1-2 weeks
Diagnosis of bronchiolitis
Based on child’s history and physical examination
Usually suspected in children <2 years of age with:
- Cough
- Wheezing
- Increased respiratory effort
Differential dianosis of bronchiolitis
Usually broad and includes:
- obstruction of airways by foreign bodies
- Retropharyngeal abscess
- Cystic fibrosis
- Congestive heart failure
Treatment of bronchiolitis
- Supportive care for outpatient and inpatient
- Maintain comfort and hydration
- Treat for fever where necessary
Fatcors which increase risk fo community-acquired pneumonia
- Age over 50 years
- Alcoholism
- Asthma
- COPD
- Dementia
- Heart failure
- Diabetes
- Immunosuppression
- Indigenous background
- Institutionalisation
- Seizure disorders
- Smoking
- Stroke
Factors that might perturb airway defence systems, pridisposing to pneumonia
- Cigarette smoke: disrupts muociliary function and macrophage activity.
- Alteration in consciousness: stroke, seizures, anaesthesia, alcohol abuse, normal sleep
- Iatrogenic manipulations: endotracheal tubes, nasogastric tubes, other respiatory therapy machinery.
- Congenital defects in ciliary activity: immotile cilia syndrome
- Underlying respiratory tract disorders: chronic obstructive pulmonary disease [COPD], bronchiectasis, cystic fibrosis
Pneumonia common bacterial causes
Common bacterial causes
- Strepcoccus pneumoniae
- Staphylococcus aureus
- Haemophilus influenzae
- Anaerobes (*Bacteroides *species; *Fusobacterium *species; Prevotella species)
- Escherichia coli
- Klebsiella pneumoniae
- *Enterbacter *species
- *Serratia *species
- Pseudomonas aeruginosa
Pneumonia intracellular/atypical bacterial causes
- Legionella pneumophila
- Mycoplasma pnumoniae
- Chlamydophila psittaci
- Chlamydophila pneumoniae
- Chlamydia trachomatis
- Mycobacterium tuberculosis
- Coxiella burnetti
Pneumonia common viral causes
Children
- Respiratory synctial virus (RSV)
- Parainfluenza virus types 1-3
- Influenza A virus
Adults
- Influenza A virus
- Influenza B virus
- RSV
- Human metapneumovirus
- Adenovirus types 4 and 7 (ie. military staff)
Fungal causes of pneumonia
- Histoplasma capsulatum
- Coccidiodes immitis
- *Rhizopus *species
- *Absidia *species
- *Mucor *species
- *Aspergillus *species
- *Candida *species
Important features of a history in pneumonia
History should define
- Clinical setting (community-acquired/hospital-acquired)
- Predisposing/underlying disorders in patients (diabetes; and see earlier slides)
- Possible exposures to specific pathogens (travel to tropical areas [Burkholderia pseudomallei; Acinetobacter baumanii]; occupation; pets)
Clinical findings in pneumonia
- Fever (elderly patients may present only with confusion)
- Rigors
- New onset cough
- Sputum production (with changes in colour)
- Chest discomfort/pain
- Dyspnoea
- Non-respiratory symptoms (fatigue; sweats; headache; nausea; myalgia)
Physical examination in pneumonia
- Body temperature (taken rectally to reduce error caused by rapid breathing)
- Tachypnoea
- Tachycardia
- BP
- State of consciousness
- Dentition
- Cyanosis
- Signs of sepsis
- Splinting (inspiratory lag on affected side)
Chest examination
- Crackles
- Consolidation: dullness on percussion
CXR (required for diagnosis): need to differentiate if new lung ingiltrate is caused by atelectasis; non-infective pneumonitis; haemorrhage; or cardiac failure.
