week 4 pleural disease Flashcards
What should a normal pleura look like
a glistening, smooth, thin membrane which covers the thoracic cavity and the lung
How is pleural fluid produced
‘filtration’ process, from parietal pleura, it’s straw-coloured
What cells are in the pleural fluid? Where do they come from?
macrophages, lymphocytes, both filtered out from blood, mesothelial cells shed from pleural surface
what does pleural fluid look like
It’s straw-coloured, little to no odour,
The pleural cavity is at what pressure
sub=atmospheric, a negative pressure
Most negative pressure of pleural cavity is at base or apex of the lung?
apex
Name three ‘important’ pleural problems
pleural effusion, pneumothorax, mesothelioma
Pleural effusion basic description
Excessive collection of fluid within the pleural cavity
Pneumothorax basic description
Collection of air between visceral pleura and parietal pleura
Combo of fluid and air collection in between visceral and parietal pleura is called what?
hydropneumothorax
What’s a pleural malignancy called?
Mesothelioma
Pus in pleural space is called what?
Empyema
Blood in pleural space is called what
hemothorax
Why does pleural effusion occur?
either excessive production, or reduced absorption
(excessive collection of fluid in pleural space)
What are the two types of pleural effusion?
transudate or exudate
transudate vs exudate
trans: purely due to filtration, low protein, non-inflam
exudate: high protein, is inflam
If exudate is high protein, what’s the cut off for classification?
3g/deciltre or more
Light’s criteria for exudate vs transudate:
Exudate: pleural fluid protien/ serum fluid protein ratio > 0.5
pleural fluid LDH levels / serum fluid LDH levels > 0.6.
Pleural fluid LDH > 2/3 ULN serum of LDH
- ULN = upper limit of normal
- LDH = lactate dehydrogenase, enzyme found in blood and other bodily fluids
Very common causes of transudate?
organ failure, such as cardiac, liver, and renal failure account for majority of transudates
2 most common:
left ventricular failure
liver cirrhosis
Transudates are rarely bilateral effusions
no, usually more often bilateral
Transudates are common with subcutaneous edema and collections of fluid elsewhere within the body
yes
Would an exudate complicate situations where there is a background of chronic transudative effusions
true
Pulmonary causes of transudative effusions are common
false, rare
Common causes of exudates
malignancy (pulmonary and non)
parapneumonic effusions, empyema
TB
So pulmonary causes for more exudate or transudate
exudate
Effusions associated with pneumonia, what type, and how often encountered with hospitalised patients with pneumonia?
exudate
25%-40%
rheumatoid arthritis can cause what type of pleural effusion
yes, exudate
Which of this list cannot cause exudates?
pulmonary emboli, clots in the lungs, benign asbestos effusions
false question, they all can
a reactive effusion due to infection or inflammation is usually what type
exudate
why would knowing the protein content of the pleural fluid bring you a step closer to working out what caused the pleural effusion?
transudate= lower protien, non inflam
exudate= higher protien, yes inflam
What order: investigation, exam, clinical history.
clinical history, exam, investigation
Why would a bedside ultrasound be good for identifying suspected effusion? (2) Limitation?
can mark site in case you want to sample fluid
more sensitive than CXR
Need to be trained
What test is done first usually to confirm or refute a pleural effusion?
chest X-Ray (easy to interpret)
Advantage of CT scan for investigation into pleural effusion?
Being more able to easily visualise underlying lung tissue, and mediastinum
How do you gain pleural fluid for testing?
needle
Pleural fluid analysis: how?
possibly bedside ABG machine
pH of pleural fluid assessment:
less than 7.2,
then in presence of pneumonia, indicate need for a chest drain
why would acidic pleural fluid need to be drained
because if acidic, likely eventually form pus, in which case infection becomes more difficult to control
Usual practice to send pleural fluid samples to:
biochemistry (culture for organisms)
microbiology (protiens and LDH, glucose)
cytology (for abnormal cells)
If fluid is transudate, what do you do
vs exudate
treat underlying cause e.g. sepsis (so may not need imaging)
exudate: treat underlying cause e.g. pneumonia, but if not clear, may need further imaging
List at least 3 causes for exudate pleural effusion, and transudate pleural effusion
Why might spontaneous pneumothorax occur
cuz of weak surfaces on the lungs called blebs, which might rupture and then leak air into the pleural cavity, accumulates and compresses the underlying lung
primary vs secondary spontaneous pneumothorax
2nd if underlying disease eg interstitial lung disease, COPD, asthma, CF
could genetic disorders predispose spontaneous pneumothorax?
occasionally
Traumatic pneumothorax example that isn’t to do with a knife injury?
blunt trauma, fractured ribs, ribs pierce lung
hydrogenic pneumothorax occur in hospital why
after CT guided biopsy, US guided biopsy, maybe on ventilator when pressure used to inflate lung will result in injury to lung and cause pneumothorax
possibly when inserting central venous line, or doing pacemaker
What is the life threatening tension pneumothorax?
air within pleural cavitybuilds up to the point that it causes pressure and pushes central structures of the chest eg trachea, and squashes other lung
And of heart: pressure of heart, doesn’t fill well, results in drop in blood oxygen levels
compression of opposite lung= drop in blood oxygen levels
escalates, can lead to cardiorespiratory arrest
how to solve tension pneumothorax?
emergency release of air under pressure, either by popping needle in or putting a chest drain on
Symptoms of tension pneumothorax?
chest pain, sob, rapid heart rate, shallow breathing, anxiety, ashen/blue skin
Presentation of spontaneous pneumothorax?
sudden, often young man, they’ve dismissed as a bit of pain after exercise
Occasionally history of biopsy, line insertion, mechanical ventilation
Examination when pneumothorax looks like:
either looking absolutely fine or not!
hypoxic
breathing fast (tachypneic)
reduced chest wall movement, reduced or no chest sounds, highly resonant
Why is it easy to miss a pneumothorax at apex?
cuz of other structurea
Can you diagnose a pneumothorax with ultrasound?
with experience, but useful when bed bound
When is a CT useful when diagnosing pneumothoraxes?
when in people with complex pneumothorax, e.g. when already COPD, or CF
Do you need to do CT for pneumothorax?
CXR would normally suffice
What are the 4 different options for pneumothorax management?
- Observe
- Aspiration (if over 2cm in size, and patient is well- just put needle and air in cavity, to suck out air)
- Chest drain insertion (place tube into pleural cavity by bedside, under local anesthetic, to create a channel for air to be ‘drained’. Left in place till pneumothorax is resolved)
- Surgery (if recurrent, unresolving events)
Are secondary pneumothorax’s likely to heal by themselves?
nah so may use chest drain
Is there a chance of recurrence for pneumothorax’s?
yes.
don’t lift heavy weights, or fly (could develop tension pneumothorax), until lung completely re-expanded.
If ipsilateral recurrence, what is suggested?
probably surgical repair
How common is it for a pleural tumor to be benign?
It’s actually rare. Usually malignant
Most pleural malignancies present as what
pleural effusions
Pleural malignanicies are more common when there is cancer elsewhere in the body. What can we infer about how common secondary vs primary pleural effusions are?
Secondary effusions are common. primary ones are not.
Secondary pleural effusions (as a type of malignancy) are usually the result of what cancer?
intra-parenchymal lung cancer
breast, ovarian, renal, GI, thyroid
What’s the most common primary malignant tumor?
malignant mesothelioma (which is rare and aggressive)
What pleural malignancy commonly arises from exposure to asbestos dust?
malignant mesothelioma (it’s pretty rare, but pretty aggressive)
Why does asbestos cause malignant mesothelioma?
fibres reach pleura
cause inflammation
this triggers repair
cycle of inflam/repair triggers tumour formation
What does malignant mesothelioma present as?
SOB, unexplained weight loss, CHEST PAIN, clubbed, palpable neck nodes
How quickly does asbestos malignant mesothelioma develop?
Between 20-40 years
Potential of mesothelioma. CXR normal. What else could be useful?
If high index of suspicion, CT thorax very useful.
For diagnosing mesothelioma, what do we need?
Tissue sample. Not just pleural fluid, which is all you need in effusion
You need to establish actual invasion of tissue
How do we obtain a pleural biopsy for diagnosing mesothelioma?
CT/US guided biopsy
Abram’s needle
Thoracoscopy (during which we can spray lining of lungwith sterile talcum powder to obliterate pleural space, and stop fluid fromre-accumulating
Are there management options for mesothelioma?
limited, it’s incurable
chemo ONLY IF FIT ENOUGH- usually not fit enough by time they’re diagnosed.
So just treat symptoms e.g. SOB, pain
Consider trials.
Patient advised to get compensation accordingly.
