Respiratory - Pleural Disease Flashcards
What is the pleural cavity?
A POTENTIAL SPACE created by the the pleural surfaces:
- parietal pleura
- visceral pleura
What is the pathophysiology of a pneumothorax.
A disorder where air enters the pleural space, separating the pleural seal and causing subsequent atelectasis of the lung.
What are the causes of pnuemothorax?
- spontaneous
- trauma
- iatrogenic (e.g. central line or pacemaker insertion)
- lung pathology (e.g. infection)
What is the investigation of choice for a simple pneumothorax?
Erect CXR
Note CT thorax can be used to detect a small pneumothorax, or to assess the size of a pneumothorax.
What are the signs of simple pneumothorax on CXR?
- area between the lung tissue and chest wall where there are no lung markings
- line demarcating the edge of the lung
Describe how to measure the size of a simple pneumothorax on CXR.
Measure horizontally from the lung edge to the inside of the chest wall, at the level of the hilum.
How should a simple pneumothorax be treated in the following conditions:
a) no SOB; pneumothorax size <2cm
b) SOB; pneumothorax size >2cm
c) bilateral pneumothoraces
a) no treatment required; it will spontaneously resolve. Follow up in 2-4 weeks.
b) aspiration and reassessment; if aspiration fails twice, insert a chest drain.
c) chest drain
What is the pathophysiology of a tension pneumothorax?
Trauma to the chest wall creates a one-way valve that lets air in to - but not out of - the pleural space. This causes air to accumulate within the pleural cavity, increasing pressure within the thorax.
As pressure rises, the mediastinum is pushed across, the large vessels are kinked and cardiorespiratory arrest can ensue.
What are the signs of a tension pneumothorax?
- tracheal deviation away from the side of pneumothorax
- reduced air entry to affected side
- hyper-resonant percussion on affected side
- tachycardia
- hypotension
What is the management of a tension pneumothorax?
Insert a large bore cannula into the second intercostal space, in the midclavicular line on the affected side.
If tension pneumothorax is suspected DO NOT wait for investigations. Once the pressure is relieved with a cannula, a chest drain is required for definitive management.
Where is a chest drain inserted?
Triangle of safety:
Super border: base of the axilla
Inferior border: 5th intercostal space
Posterior border: lateral edge of Latissimus dorsi
Anterior edge: lateral edge of the Pectoris major
In a chest drain, why is a needle inserted just above the rib?
Avoids the intercostal neurovascular bundle that runs below the rib.
What discharge advice should be offered to patients with pneumothorax?
No flying or driving until the pneumothorax has resolved.
What is a pleural effusion?
A collection of fluid within the pleural cavity.
The fluid can be either exudative (high protein count), or transudative (low protein count).
Give some causes of exudative pleural effusion.
- lung cancer
- tuberculosis
- rheumatoid arthritis
- pneumonia
- drugs
Give some causes of transudative pleural effusion.
- congestive heart failure
- hypoalbuminaemia (e.g. nephrotic syndrome, peritoneal dialysis)
- hypothyroidism
- pulmonary embolism
If pleural fluid protein level between 25 and 35g/L, how can transudative and exudative causes of pleural effusion be determined?
Light’s criteria says pleural effusion is exudative if:
Pleural fluid / serum protein > 0.5
or
Pleural fluid / serum LDH > 0.6
or
Pleural fluid LDH >2/3 the upper limit of normal
Presentation of pleural effusion.
- shortness of breath
- dullness to percussion over the effusion
- reduced breath sounds
- tracheal deviation away from the effusion
What are the CXR findings consistent with pleural effusion?
- blunting of costophrenic angle
- fluid in the lung fissures
- large effusions will have a meniscus
- tracheal / mediastinal deviation
How should pleural effusion be investigated?
- CXR
- ECG
Taking a sample of the pleural fluid by ultrasound guided aspiration is required to analyse it for protein count, cell count, pH, glucose, LDH and microbiology testing.
How should pleural effusion be treated?
Small effusions will resolve with treatment of the underlying cause.
Large effusions need pleural aspiration or chest drain.
NOTE never insert a chest drain unless the diagnosis is well established, otherwise draining all fluid may hinder the opportunity to obtain pleural biopsies.
What is empyema?
An infected pleural effusion.
Presentation of empyema.
Patient with improving pneumonia but new or ongoing fever.
Investigation of empyema.
Pleural aspiration, showing:
- pus
- pH < 7.2
- low glucose
- high LDH
Management of empyema.
Empyema is treated with antibiotics and an URGENT chest drain to remove the pus.
