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103 - Heart, Lungs, Blood
Theme 2: Lungs and Gas Exchange
T2 L18: Pleural and chest wall disease
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What is the pleura?
delicate
serous membrane
arranged as a sac
enclosing the lungs at lines of the thoracic cavity
Visceral:
covers surface of lungs and goes into fissures
; attached directly to lungs
Parietal: lines
inner chest wall
What is the intrapleural space and what are its properties?
space between
visceral
and
parietal pleura
contains 10 to 20 mL of fluid as
lubricant
continuously produced and absorbed by the
lymphatic system
What is pleural effusion?
accumulation of
fluid
in
intrapleural space
exceeding physiological amounts (10-20mL)
pathophysiology: changes in fluid & solute homeostasis. Mechanism determines if:
exudate
(leaky vessels) or
transudate
(intact vessel)
may present as
primary manifestation
or secondary (
complication
)
What is the epidemiology of pleural effusion?
relates to
underlying disease
thus present at all ages
What is the clinical presentation of pleural effusion?
depends on
fluid volume
(small volume can be asymptomatic)
symptoms:
breathlessness
,
chest pain
How is pleural effusion diagnosed?
Examination:
dullness to percussion
(
stony dull
) &
decreased breath sounds
Thoracic imaging: Chest
X-Ray,
CT, thoracic ultrasound, thoracocentesis, thoracoscopy, biopsy
What does this image show?
chest X-ray
left pleural effusion
What does this image show?
CT thorax
Pleural mass
Loculated left pleural effusion
What does this image show?
ultrasound
pleural effusion
What is transudative pleural effusion?
caused by
fluid leaking through intact blood vessels
causes:
increased hydrostatic pressure
(eg cardiac failure)
decreased plasma oncotic pressure
(eg liver cirrhosis)
What is exudative pleural effusion?
Fluid accumulation in the pleural space due to
inflammation
or
injury
through
leaky blood vessels
/ lymphatics
Causes:
increased capillary permeability
due to localised ruptures
decreased absorption
eg lymphatic blockage
What is Light's criteria?
for
exudative effusion.
Has 1 or more of:
Pleural fluid protein/serum protein >0.5
Pleural fluid LDH/Serum LDH > 0.6
Pleural fluid LDH >2/3 the upper limit of normal of serum LDH
98% sensitive and 83% specific
What are the possible causes of transudate pleural effusion?
cardiac failure
cirrhosis
nephrotic syndrome
What are the possible causes of exudate pleural effusion?
malignancy
pneumonia
tuberculosis
mesothelioma
rheumatoid arthiritis
What is pleural infection?
bacteria enter
pleural space
:
direct
eg
pneumonia
indirect
eg blood borne infection
Confirmed on: microbiology,
Light's criteria
males m
ore likely
What is empyema?
severe pleural infection
symptoms:
breathlessness
,
chest pain
,
persistent fever
Pleural tap
:
appearance frank pus
pleural fluid pH <7.2
only
20
% will get an organism
Management:
chest drain
and
antibiotics
for at least 6 week
What is Haemothorax?
blood in chest
if occurs with pneumothorax:
haemopneumothorax
presents with
breathlessness
&
chest pain
history of
trauma
or
malignancy
treatment:
chest drain
& thoracoscopic surgery
What is Pneumothorax?
air in intrapleural space
primary spontaneous
:
no underlying lung disease
age <
50
years
no smoking history
secondary spontaneous:
underlying lung disease
Age >
50
years
Smoker
symptoms:
shortness of breath
,
chest pain
Clinical features:
reduced/no air entry on affected site
,
hyperresonant to percussions
,
tracheal shift
(tension Px)
Management:
conservative
,
aspiration
,
chest rain
What is respiratory muscle weakness?
Consequence of
neuromuscular diseases
(E.g. Amyotrophic lateral sclerosis, Guillian-Barre syndrome, Duchenne muscular dystrophy)
Symptoms: nonspecific (fatigue, poor concentration, dyspnoea, orthopnoea)
How is respiratory muscle weakness examined?
Physical examination:
increased resp rate
,
alternate ribcage/abdominal breathing
,
accessory muscle use
,
unable to clear mucus
,
impaired swallow
Pulmonary function testing:
preserved total lung capacity
,
elevated residual volume
,
reduced vital capacity
How is respiratory muscle weakness managed?
long-term non-invasive positive pressure ventilation
What is kyphoscoliosis?
abnormal curvature of spine
cause - various
respiratory implications:
restrictive lung defect
/
respiratory failure