18.2 Pneumonia Flashcards
What is pneumonia?
Inflammation of the lower respiratory tract in which the alveolar spaces are filled with fluid and inflammatory cells.
Chest infection is a general term, not all chest infections are pneumonia.
What are the signs of a chest infection?
- Productive cough
- Yellow or green sputum
- Shortness of breath
What are the 3 classifications on pneumonia?
- Community acquired pneumonia (CAP)
- Hospital acquired pneumonia
- Healthcare-acquired pneumonia: acquired from outpatient clinic, nursing home or long-term care facility
What is the community definition of pneumonia?
- Symptoms of acute LRTI
- New focal signs on chest examination
- At least one systemic feature
- No other explanation for illness
What is the hospital definition of pneumonia?
- An infection of the lungs that occurs during a hospital stay, plus additional shadowing on chest X-ray
What are common pneumonia causing pathogens?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Staphylococcus aureus
- Pneumonia can be caused by bacteria, viruses and fungi
- Pneumonia can also be non-infective, e.g. caused by a connective tissue condition such as lupus
Describe the pathophysiology of pneumonia.
- Fluid and exudate fill the alveoli
- In severe pneumonias, this causes hypoxia as gas exchange cannot take place
- Lobular pneumonia: might only affect 1 lobe
- Bronchopneumonia: inflammation of the terminating bronchioles
Describe the incidence of CAP.
- 5-11 cases per 1000 adults
- Diagnosed in 5-12% of adult patients who present to GP with symptoms of an LRTI
- 22-42% of pts who present to GP with CAP are admitted to hospital
Describe the mortality rates for pneumonia.
- <1% for those cases managed in the community
- 6-14% for those admitted to hospital with CAP
- > 30% for those admitted to an ICU
- 60% of pneumonia deaths occur in pts aged over 84
What does the term nosocomial pneumonia refer to?
Healthcare/hospital associated pneumonia.
How do the types of pathogens causing pneumonia differ between types of pneumonia?
- CAP = mostly gram positive bacteria
- Late nosocomial = mostly gram negative
- Immunocompressed = opportunistic pathogens
Is CAP only caused by bacteria?
No, can be caused by viruses.
E.g. Influenza A or B
What should be noted when taking a history from a suspected pneumonia patient?
- Recent travel (Spain and Italy overprescribe abx, pt may be ill with a very resistant strain)
- Pets (birds can cause illness)
- Smoking
- Occupational (e.g. healthcare worker)
What investigations are often carried out for pneumonia?
- Liver function test: albumin levels
- C-reactive protein test
- CXR = chest X-ray
- Urine sample to check for legionella and pneumococcal antigens
- Arterial blood gas: needle injected into radial artery to measure oxygen and carbon dioxide levels
Where is the shadowing in this CXR?
Right lung shadowing, called a consolidation, due to fluid in alveolar spaces.
What score is used to assess the severity of CAP?
CURB-65 score
What is the CURB-65 score?
Used to assess severity of CAP.
- Confusion
- Urea (are kidneys affected?)
- Respiratory rate
- Blood pressure
- Aged 65+
Assessment of severity influences whether patient should be an inpatient or outpatient, guides investigation choices, guides management and antibiotic therapy, consideration of ITU support.
How does the CURB-65 score categorise patients?
- Non-severe
- Intermediate
- Severe
What does compus mentus mean?
Not confused, sound mind.
What would this patient’s CURB-65 score be?
3 (severe)
How would you manage this patient?
- Oxygen
- Analgesia for chest pain
- IV fluids
- Antibiotics, make sure to follow national and local guidelines, Abx stewardship
- Thromboprophylaxis
- Nutritional support
- Regular review
What are the antibiotic recommendations for adult patients with CAP?
- Low severity = amoxicillin 500mg TDS (if allergic, doxycycline)
- Moderate severity/intermediate = amoxicillin 500mg-1.0g TDS + clarithromycin 500mg BD
- High severity = co-amoxiclav 1.2g TDS IV + clarithromycin 500mg BD IV
What are the possible complications of pneumonia?
- Para-pneumonic pleural effusion
- Lung abscess: bacteria cause a cavitation to form
- Septicaemia: bacteria enter blood stream- haematogenous spread e.g. meningitis, peritonitis, septic arthritis, endocarditis
- Respiratory failure and hypotension
- Atrial fibrillation and other cardiac complications
Why does antibiotic choice differ with severity of disease?
- Certain microorganisms are more prevalent with each classification (i.e. CAP vs early nosocomial vs late nosocomial)
