Pneumonia Flashcards
What is pneumonia?
Pneumonia is characterised by acute inflammation with an intense infiltration of neutrophils in and around the alveoli and the terminal bronchioles. The affected bronchopulmonary segment or the entire lobe may be consolidated by the resulting inflammation and oedema.
What are risk factors for developing pneumonia?
- Age: young and elderly
- Lifestyle: smoking, alcohol
- Preceding viral infections: Streptococcus pneumoniae
- Respiratory: asthma, COPD, malignancy
- Immunosuppression
- Intravenous drug abuse, often associated with Staphylococcus aureus infection
- Aspiration pneumonia
- Hospitalisation - often involving Gram-negative organisms.
What usually causes viral pneumonia?
Streptococcus pneumoniae
What are the main causes of community-acquired pneumonia?
S. pneumoniae, S. aureus, Mycoplasma pneumoniae, Haemophilus influenzae, Chlamydophila pneumoniae and respiratory viruses
What is the presentation of community-acquired pneumonia?
Symptoms: cough, purulent sputum, breathlessness, fever, malaise.
Signs: tachypnoea, bronchial breathing, crepitations, pleural rub, dullness with percussion.
When would you admit someone with community-acquired pneumonia?
NICE CRB65 score of 2 or higher
Confusion
RR > 30
S-BP < 90
Age > 65
How would you manage community-acquired pneumonia?
Patients with suspected CAP should be advised not to smoke and to rest and drink plenty of fluids
Also: oxygen, NSAIDs
Those who fail to improve after 72 hours of treatment should be advised to seek further medical advice
Antibacterials are recommended in all suspected cases of pneumonia, starting as soon as possible
What antibiotic would you give for low-severity community-acquired pneumonia?
five-day course of amoxicillin
clarithromycin, erythromycin (in pregnancy) or doxycycline for patients allergic to penicillin or if atypical pathogen suspected
What antibiotic would you give for high-severity community-acquired pneumonia?
For high-severity CAP a five-day course of co-amoxiclav with clarithromycin or erythromycin (in pregnancy) should be offered. The oral or intravenous route can be used
Levofloxacin orally or IV is an option for patients allergic to penicillin.
What are causes of atypical pneumonia?
M. pneumoniae
C. pneumoniae
Legionella pneumophila
What is a hospital-acquired pneumonia?
This is defined as a new infection of lung parenchyma appearing more than 48 hours after admission to the hospital.
What are the causes of hospital-acquired pneumonia?
Infection occurring less than five days after hospital admission is usually caused by S. pneumoniae.
Infection occurring after this time is usually caused by H. influenzae , methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and other non-pseudomonal Gram-negative bacteria.
Who is most at risk for hospital-acquired pneumonia?
It occurs mostly in patients who are severely debilitated, immunocompromised or mechanically ventilated.
What investigations would you do for a suspicion of hospital-acquired pneumonia?
FBC with differential white cell count. CRP (to aid diagnosis and as a baseline measure). Renal function and electrolytes. LFTs. Blood cultures. CXR
What are complications following pneumonia?
Pleural effusion Empyema Lung abscess DVT Septicaemia, pericarditis, endocarditis, osteomyelitis, septic arthritis, cerebral abscess, meningitis AKI
What is empyema?
Puss in the pleural space
Explain the anatomy of the pleural membrane?
This is a serous membrane divided into the visceral pleura (lines the lungs) and parietal pleura (lines the internal thoracic cavity).
The potential space between the visceral and parietal pleura contains a small amount of lubricating serous fluid.
The serous fluid allows the visceral and parietal pleura to slide over each other during respiration and creates surface tension between the two layers.
What are the characteristics of a transudate?
Protein <30 g/L
Transudative pleural effusions are defined as effusions that are caused by factors that alter hydrostatic pressure, pleural permeability, and oncotic pressure.
What are the characteristics of an exudate?
Protein > g/L
Exudative pleural effusions are caused by changes to the local factors that influence the formation and absorption of pleural fluid.
The fluid is considered an exudate if any of the following are present:
- The ratio of pleural fluid to serum protein is greater than 0.5
- The ratio of pleural fluid to serum LDH is greater than 0.6
- The pleural fluid LDH value is greater than two-thirds of the upper limit of the normal serum value
What are the causes of a transudate?
Congestive heart failure
Liver cirrhosis
Severe hypoalbuminemia
Nephrotic syndrome
What are the causes of an exudate?
Malignancy
Pneumonia
Infection (e.g. empyema due to bacterial pneumonia)
Trauma
What does a purulent effusion fluid suggest?
empyema
What does a milky effusion fluid suggest?
hylothorax or pseudochylothorax
This is most often caused by lymphatic obstruction secondary to malignancy, chronic inflammation or thoracic duct injury by trauma or a surgical procedure
What does a grossly bloody effusion fluid suggest?
trauma
What do pleural fluid LDH levels > 1000 IU/L suggest?
Levels greater than 1000 IU/L are suggestive of empyema, malignancy or rheumatoid effusion.
What does low glucose in the pleural fluid suggest?
Infection!
Empyema, rheumatoid pleuritis, TB
What is, usually, the white blood cell count in exudates?
greater than 50,000 cells/µL
What is, usually, the white blood cell count in transudates?
ess than 1000 cells/µL
What is the management of empyema?
Drain all the pleural fluid
How is pneumonia diagnosed?
CXR, symptoms, bloods
What is the pathophysiology of pleural fluid?
Pleural fluid is secreted by the parietal layer of the pleura and reabsorbed by the lymphatics in the most dependent parts of the parietal pleura, primarily the diaphragmatic and mediastinal regions. Exudative pleural effusions occur when the pleura is damaged, e.g., by trauma, infection, or malignancy, and transudative pleural effusions develop when there is either excessive production of pleural fluid or the resorption capacity is reduced
What criteria are used to distinguish between an exudate and a transudate?
Light’s criteria
How would you diagnose a pleural effusion?
Decreased breath sounds
CXR
Medical history
When would you perform thoracentesis?
pleural fluid that is at least 10 mm in thickness on CT or CXR
After thoracentesis, what factors would you investigate?
- Chemical composition including protein, lactate dehydrogenase (LDH), albumin, amylase, pH, and glucose
- Gram stain and culture to identify possible bacterial infections
- White and red blood cell counts and differential white blood cell counts
- Cytopathology
- Other tests as suggested by the clinical situation
What is the appearance of a transudate versus exudate?
Trans: clear
Ex: cloudy
What is the fluid protein/serum protein of a transudate versus exudate?
Trans: < 0.5
Ex: > 0.5
Anatomically, where would you perform thoracentesis?
The conventional site for aspiration is posteriorly, approximately 10 cm lateral to the spine (mid-scapular line) and 1-2 intercostal spaces below the upper level of the fluid.
Use local anaesthetic (5-10 ml of 1% lidocaine) to infiltrate the skin and underlying tissues. A 25G needle can be used for this.
What performing thoracentesis, you want to avoid intercostal nerves. Where do you insert your needle?
Avoid the intercostal nerves and vessels that run immediately beneath the rib by inserting the needle just above the upper border of the rib, below your mark.
What is chylothorax?
This is the presence of chyle in the pleural space. It usually occurs because of disruption of the thoracic duct.
Causes include:
- Neoplasm: lymphoma, metastatic carcinoma.
- Trauma: operative and penetrating injuries.
What is pseudochylothorax?
This is the accumulation of cholesterol crystals in a long-standing pleural effusion. Causes include:
TB.
Rheumatoid arthritis.
Poorly treated empyema.
What is a bilateral effusion a sign of?
Bilateral effusions in a clinical setting strongly suggestive of a pleural transudate: systemic problem
What does low pleural pH implicate?
Infection
Pleural infection and empyema. Rheumatoid disease and systemic lupus erythematosus (SLE). TB. Malignancy. Oesophageal rupture.
How do you manage pleural effusions?
- Drain
- Talc
- Pleurodesis
