23. LRTIs: Pathology, Management and Clinical Features Flashcards
What are the main infections of the lower respiratory tract? (6)
- acute bronchitis
- exacerbation of COPD
- pneumonia
- empyema
- lung abscess
- bronchiectasis
What is acute bronchitis?
- short-term inflammation of large airways e.g. bronchi
- self-limiting illness which lasts a couple of weeks
- often caused by viral infection
What is empyema?
- pus in pleural space
- suspected if patient with resolving pneumonia develops a recurrent fever
- may or may not follow a documented episode of pneumonia
What is the UK incidence for pneumonia?
between 5-11 per 1000 adult population
What percentage of community diagnosed pneumonia require hospitalisation in UK?
between 22-42%
What is the mortality percentage of hospitalised patients with pneumonia?
5.7-12%
Why is pneumonia difficult to diagnose initially?
Symptoms in the early start are very vague and fit other respiratory infections
What are the symptoms of pneumonia? (8)
- malaise
- fever
- chest pain (pleuritic)- very sharp
- cough
- purulent sputum (rusty colour)
- dyspnoea
- headache
- haemoptysis
What are signs of pneumonia?
- pyrexia
- tachpnoea
- central cyanosis
- dulness of percussion of affected lobe
- bronchial breath sounds
- inspiratory crepitations/crackles
- increased vocal resonance
What are bronchial breath sounds indicators of in terms of lungs? (6)
- lung consolidation
- cavitation
- mass interposed between chest wall and large airways
- tension pneumothorax
- complete alveolar atelectasis/ collapse with patent airways
- pleural effusion with atelectasis
What is bronchial breathing like?
- louder and higher pitched than vesicular breath sounds
- no ventilation to alveoli and sound that is heard originates from bronchi and is transmitted through the chest wall
Bronchial breathing where is an abnormal sign?
Anywhere other than over trachea, right clavicle or right interscapular space is abnormal
What is a consolidated lung?
- Region of lung that has filled with liquid, marked by induration (swelling or hardening of normal lung tissue) of a normally aerated lung
- increase in fibrous elements, loss of elasticity
- hardened mass
What investigations are done for pneumonia patients?
- Serum biochemistry and full blood count
- Chest X Ray
- Blood cultures
- Throat swab (for atypical pathogens)
- Urinary legionella antigen
- Sputum microscopy and culture
What investigation is mandatory in feverish patients?
Blood culture
What disease is a form of atypical pneumonia caused by any form of Legionella bacteria?
Legionnaires’ Disease (caused by Legionella)
What diagnostic technique is commonly used in pneumonia patients?
Air bronchograms: tubular outline of airways made visible by filling surrounding alveoli by fluid or inflammatory exudates.
What are the most common pathogens causing pneumonia as identified by microbiology? (from most to least common) (7)
- strep pneumoniae
- All other viruses
- H. influenzae
- Mycoplasma pneumoniae
- Chlamydia psittaci
- S. aureus
- Legionella
Where does Legionella bacteria usually live?
Grows in water systems, in stagnant and unclean water
What are 2 atypical pathogens?
- mycoplasma pneumoniae
2. chlamydia psittaci
Pneumonia patients are assessed to determine what?
- their treatment
- whether patient should be admitted not not
What is the criteria for severity scoring in pneumonia patients? (CURB 65)
C: confusion U: blood urea >7 R: respiratory rate>30 B: diastolic blood pressure<60 6:5: age>65
What is the scoring system for pnuemonia patients? (0-5)
0= low risk and could be treated in community
1-2: hospital treatment usually required
3-5: high risk of death and need for ITU (intensive therapy unit)
What is the treatment for CURB 0-1 patient score?
Amoxycillin or clarithromycin/ doxycycline
What is the treatment for CURB 2 patient score?
Amoxycillin and clarithromycin or levofloxacin
What is the treatment for CURB 3-5 patient score?
Co-amoxiclav (broader spectrum so used in more severe cases) and clarithromycin or levofloxacin (if penicillin allergic)
What are 4 main additional treatments for pneumonia?
- Oxygen
- IV fluids
- CPAP; continuous positive airway pressure
- Intubation
When is CPAP given to pneumonia patients?
If not able to oxygenate patient (in severe cases intubation and ventilation may be required)
What are complications of pneumonia? (SLAP HER)
S: septicaemia
L: lung abscess
A: atrial fibrillations + ARDS (acute resp. distress syndrome)
P: pericarditis/ myocarditis
H: haemolytic anaemia (mycoplasma) and hypotension
E: empyema
R: respiratory failure, type 1 common
What is septicaemia? (sepsis)
- If immune system is weak and infection in body severe, it causes immune system to go into overdrive and inflammation affects the entire body.
- Widespread inflammation can cause tissue and organ damage and interferes with blood flow
- Most common sites of infection leading to sepsis are: lungs, urinary tract infection, abdomen and pelvis
Acute kidney injury as a pneumonia complication affects which group of people?
Particularly the elderly with co-morbidities
What is haemolytic anaemia as a pneumonia complication?
Immune phenomenon where RBCs are destroyed
What is ARDS? (Acute respiratory distress syndrome)
- occurs due to lung injury or secondary to sever systemic illness
- inflammatory mediators as a result of lung damage are released causing increased capillary permeability and non-cardiogenic pulmonary oedema
- often accompanied by multiorgan failure
What are conditions which need to undergo differential diagnosis when diagnosing pneumonia?
- TB
- lung cancer
- pulmonary embolism
- cardiac failure
- pulmonary vasculitis (Wegners granulomatosis )
How to distinguish between TV and pneumonia?
- TB is infection of mainly upper lobes (likes airated lung tissue), has sub-acute or chronic cause and patient usually unwell for several weeks
- Pneumonia has a short history of symptoms of around a week
What are the main 3 groups of pathogens which cause empyema?
- streptococcus (52%)
- staph. aureus (11%)
- anaerobes (20%)
What are symptoms of empyema?
- chest pain
- absence of cough (or dry)
- high and swinging fever and night sweats
- lack of energy/malaise
What diagnostic techniques are used to investigate empyema? (3)
- CT of thorax
- pleural ultrasound
- diagnostic pleural aspiration (pH<7.2)
What are the treatment options for empyema? (2)
- chest drain
-antibiotics
(t-PA/DNase sometimes required)
How long could the antibiotic treatment last for while treating empyema?
up to 6 weeks (depending on clinical response)
If none of the treatments for empyema work, what option is left?
surgery for patients who are not improving
What is a lung abscess?
- Cavitating area of localised and suppurative infection within the lung
- Necrosis of lung tissue forming cavities of more than 2cm which are filled with necrotic debris and fluid
What 3 organisms are more likely to result in cavitating pneumonia? (3)
- staph aureus
- pseudomonas
- anaerobes
What are symptoms for a lung abscess?
not very specific: - Lethargy/ lack of energy - weight loss -high swinging fever - foul-smelling sputum -pleuritic chest pain (empyema develops in 20-30% patients)
What investigations should be done for a lung abscess?
- CT of thorax
2. sputum culture (including TB microscopy and culture)
What is the treatment for a lung abscess?
prolonged antibiotic treatment
What is the drainage via in a lung abscess?
Drainage via bronchial tree but occasionally percutaneous drainage may be necessary
Is bronchiectasis a chronic or acute infection?
Chronic
What is bronchiectasis?
Chronic infection of the bronchi and bronchioles leading to permanent dilation of these airways
What are main organisms which cause bronchiectasis?
- H influenzae
- Strep pneumoniae
- Staph aureus
- Pseudonomas aeruginosa
What are the main causes of bronchiectasis? (most of the time causes not found but these are potential)
- idiopathic
- immotile cillia syndrome
- cystic fibrosis (at early age)
- childhood infections such as measles or whooping cough
- hypogammaglobulinaemia
- . Allergic Bronchopulmonary Aspergillosis (ABPA)
What is hypogammaglobulinaemia?
- genetic and can be acquired (secondary)
- not enough immunoglobulin gamma globulin is produced in the blood
- therefore infections can’t be fought
What is ABPA? (allergic bronchopulmonary aspergillosis)
- exaggerated response of the immune system to fungus Aspergillus
- occurs most commonly in CF and asthma patients
What are symptoms of bronchiectasis?
- chronic cough
- daily sputum production (often copious/large amounts)
Sometimes:
-wheeze
- dyspnoea
-tiredness (chronic)
- flitting chest pains (between both lungs)
-haemoptysis
What are common signs of bronchiectasis? (3)
- finger clubbing
- course inspiratory crepitations/crackles (auscultation)
- wheeze (asthma, COPD, ABPA)
What is the investigation for bronchiectasis? (5)
- High resolution CT thorax
- Sputum culture
- Serum immunoglobulins
- Total IgE and Aspergillus precipitins (when antibody reacts with antigen it produces a precipitate)
- CF genotyping
What antibiotic can haemophilus influenzae be resistant to for treatment of bronchiectasis?
amoxicillin
What is the treatment for bronchiectasis? (3); similar to asthma treatment
- chest physiotherapy
- prompt treatment of infections with antibiotics
- may require inhaled therapy including beta 2 agonist and inhaled corticosteroids
