Respiratory (Pleural diseases and lung cancer)

Question 1

pneumothorax

Answer 1

collection of air in the pelural space

can be primary or secondary

Question 2

Primary spontaneous pneumothorax

Answer 2

These occur in people without lung disease, however, there are risk factors:

• Smoking
• Male sex
• Family history
• Tall and slender build, especially people with Marfan’s syndrome
  *

Question 3

Secondary spontaneous pneumothorax

Answer 3

These occur in people who have lung disease. Risk factors are:

• Asthma
• COPD
• Idiopathic pulmonary fibrosis
• Connective tissue diseases such as rheumatoid arthritis
• Tuberculosis
• Pneumocystis jirovecii pneumonia in people who have HIV

Question 4

other causes of pneumothorax

Answer 4

Traumatic pneumothorax:

• Often following penetrating chest trauma (e.g. stabbing, gunshots, fractured ribs)

Iatrogenic pneumothorax:

• Common causes are mechanical ventilation, central line placement, and lung biopsy

Catamenial pneumothorax – pneumothorax at the time of menstruation

• Due to thoracic endometriosis

Question 5

presentation of pneumothorax

Answer 5

• Dyspnoea
• Pleuritic chest pain: This is chest pain that is worse when breathing in
• Tachypnoea

Examination may show:
* Ipsilateral reduced breath sounds
* Ipsilateral hyper-resonance on percussion

Question 6

pneumothorax: severe signs of respiratory distress and haemodynamic instability may suggest

Answer 6

presence of tension pnuemothorax

Question 7

pathophysiology of tension pneumothorax

Answer 7

In a tension pneumothorax, injured pleural tissue leads to the formation of a one-way valve. This allows air to enter the pleural space during inspiration, but it cannot escape during expiration, leading to an increase in intrathoracic pressure.

** Obstructive circulatory** shock follows, where the heart, lungs, and major blood vessels are compressed, leading to haemodynamic compromise.

Risk factors are similar to that of a pneumothorax, along with blunt or penetrating chest trauma (such as knife stabbings).

Question 8

presentation of tension pneumothorax

Answer 8

haemodynamic instability should

• Tracheal deviation away from the affected side – due to increasing intrathoracic pressure as more air enters
• Signs of respiratory distress:
• Hypotension – due to cardiac outflow obstruction
• Tachycardia – due to the heart trying to compensate for outflow obstruction
• Altered levels of consciousness
• Sweating

Question 9

investigations for normal pneumothorax

Answer 9

Chest x-ray(posteroanterior):
* Done initially and shows a visible rim between the lung margin and chest wall and absent lung markings between the lung margin and chest wall

Chest CT:
* Considered if the diagnosis is uncertain or there is a complex case

Arterial blood gases:
* Should only be done if oxygen saturations are <92%
* Usually shows hypoxia depending on the severity

Question 10

investigation for tension pneumothorax

Answer 10

nil- straight to needle decompression

Question 11

classification of size of pneumothorax

Answer 11

The size of the pneumothorax affects the rate of resolution and is used to guide whether management is carried out. The distance between the pleural surface and the lung edge is measured at the level of the hilum:

If ≤2cm – small pneumothorax
If >2cm – large pneumothorax

Question 12

Management: Primary pneumothorax

Answer 12

Always remember to rule out a tension pneumothorax.

• If <2cm and patient is not short of breath: discharge and review as an outpatient
• If >2cm and/or patient is short of breath: Attempt aspiration. If aspiration fails, insert a chest drain

-> 2nd intercostal muscle or triangle of safety

Question 13

Management: Secondary pneumothorax

Answer 13

• If >50 years old + >2cm and/or patient is short of breath: insert a chest drain
• If 1-2cm: attempt aspiration
• If aspiration fails, insert a chest drain
• If <1cm: give oxygen and admit for 24 hours and review

Question 14

management of recurrent pneumothorax

Answer 14

pleurectomy, pleural abrasion and pleurodesis

Question 15

management of tension pneumothorax

Answer 15

1. Immediate decompression + high flow oxygen– insert a large-bore cannula through the second intercostal space in the mid-clavicular line:
   * A ‘hiss’ of air arising can confirm the diagnosis
2. Insert chest drain immediately after decompression and admit to hospital: This is inserted into the ‘triangle of safety’ – mid-axillary line of the 5th intercostal space

Question 16

Pleural effusion

Answer 16

When excessive fluid accumulates in the pleural space, this is known as a pleural effusion.

Question 17

causes of pleural effusion can be split into

Answer 17

Transudate and Exudate

The causes of pleural effusion can be transudates or exudates depending on their protein

Question 18

transudate

Answer 18

protein <30g/L

occurs due to increased hydrostatic pressure

• congestive heart failure
• cirrhosis
• nephrotic syndrome
• PE
• hypoalbuminemia
• Hypothyroidisms
• Meigs syndrome

Question 19

exudate

Answer 19

protein >30g/l

occurs due to inflammation and increased capillary permeability
- pneumonia
- cancer
- TB
- PE
- autoimmune
- pancreatitis

Question 20

presentation of pleural effusion

Answer 20

• Dyspnoea:
• Dullness to percussion on examination:
• Reduced breath sounds over the area of effusion
• Pleuritic chest pain
• Cough
• Features of associated conditions such as heart failure

Question 21

pleural effusion investigations

Answer 21

Chest x-ray:

• Shows blunting or blurring of the costophrenic angles
• Shows a clear fluid level
• The trachea deviates away from the opacification

Thoracic ultrasound:

• Useful for guiding thoracentesis and more specific than X-rays for detecting pleural effusions

CT with contrast:

• To investigate underlying cause

Pleural aspiration + microscopy, culture, sensitivities, cytology, and biochemistry:
Done with ultrasound guidance

• Exudates:
  Protein level >30 g/L
• Transudates:
  Protein level <30 g/L
  If the protein level is borderline (between 25-35 g/L), use Light’s criteria (see below)

Question 22

Pleural Fluid Interpretation

Answer 22

Blood

• Malignancy
• Pulmonary embolism
• Trauma

Pleural pH
Reduced pleural pH (<7.20) can be caused by:

• Infection
• Empyema
• Malignancy
• Connective tissue diseases – rheumatoid arthritis and systemic lupus erythematosus
• Tuberculosis
• Oesophageal rupture

Pleural glucose

Reduced pleural glucose (<3.3 mmol/L) can be caused by:

• Empyema
• Malignancy
• Connective tissue diseases – rheumatoid arthritis and systemic lupus erythematosus
• Tuberculosis
• Oesophageal rupture

Other measures

• White cell count and differential: Elevated counts suggest malignancy or tuberculosis
• Lactate dehydrogenase (LDH): Used in Light’s criteria (see below)
• Pleural fluid amylase: Elevated counts suggest pancreatitis or oesophageal rupture

Question 23

Light’s criteria for pleural effusion

Answer 23

Light’s criteria should be used if the pleural fluid protein level is between 25-35 g/L. An exudate is likely if any one of the following applies:

• Pleural fluid divided by serum protein is >0.5
• Pleural fluid LDH divided by serum LDH >0.6
• Pleural fluid LDH more than 2/3s of the upper limit of normal serum LDH

Question 24

management of pleural effusion

Answer 24

• 1st-line: pleural aspiration:
  This is involved in diagnosing and identifying the underlying cause of the effusion and may provide therapeutic relief, however, the effusion can often recur
• Chest drains may be inserted which are then removed once the underlying cause has been treated
• Other options include surgical shunts, indwelling drainage catheters, or pleurodesis (adhesion of the visceral and parietal pleura)

Question 25

lung cancers are usually

Answer 25

bronchial carcinomas
* Non-small cell lung cancers (NSCLCs) – around 85% of cases
* Small cell lung cancers (SCLCs) – around 15% of cases

Question 26

Lung cancer metastases are common and typical sites are

Answer 26

the bone, kidney, breast, prostate, GI tract, ovaries, and cervix.

Question 27

Non-small cell lung cancers (NSCLCs)

They can be further divided into:

Answer 27

1) Adenocarcinoma
2)
* Most common type
* Often seen in non-smokers
* Lung periphery

2) Squamous carcinoma (smoking key risk factor)
3)
* Often presents as an obstruction of the bronchus leading to infection

3) Large cell carcinoma

4) Carcinoid tumours - flushing, diarrhoea

Question 28

Small cell lung cancers (SCLCs)

Answer 28

Small cell lung cancers (SCLCs) arise from Kulchitsky cells which are part of the amine precursor uptake and decarboxylation (APUD) system. APUD cells make polypeptides and amines that act as hormones or neurotransmitters. SCLCs often have paraneoplastic features (see below) as a result of this.

Smoking key RF

SCLCs carry a poor prognosis as they are aggressive and rapidly growing. They often spread early and are nearly always inoperable at presentation.

Question 29

Risk Factors of lung cancers

Answer 29

• Active or passive smoking
• Chronic obstructive pulmonary disease (COPD)
• Increased age
• Family history
• Asbestos exposure

Question 30

presentation of lung cancer

Answer 30

• Dyspnoea
• Cough
• Haemoptysis- red flag
• Unexplained weight loss- red-flag
• Chest pain or discomfort
• Hoarseness: some tumours, particularly Pancoast tumours (tumours of the apex of the lung) can press on the recurrent laryngeal nerve, leading to hoarseness
• Horner’s syndrome
• Features of paraneoplastic syndromes – see below

Question 31

Paraneoplastic syndromes of lung cancer

Answer 31

is a set of signs and symptoms emerging as a consequence of a tumour in the body, typically due to the production of molecules (such as hormones) by tumour cells, or the immune response against the tumour itself. Paraneoplastic syndromes vary depending on the type of lung cancer present.

Question 32

paraneoplastic syndrome: adenocarcinoma

Answer 32

Gynaecomastia due to ectopic hCG secretion:
The hCG acts as LH and stimulates the production of more oestrogen

Question 33

paraneoplastic syndrome: small cell arcinoma

Answer 33

• Ectopic anti-diuretic hormone (ADH) secretion leading to a syndrome of inappropriate ADH secretion (SIADH) resulting in hyponatraemia
• Ectopic adrenocorticotropic hormone (ACTH)secretion leading to features of Cushing’s syndrome
• Lambert-Eaton myasthenic syndrome (LEMS) due to the formation of antibodies against voltage-gated calcium ion channels:
• These are antibodies that are made against the tumour cell that happen to also act against voltage-gated calcium ion channels

Question 34

paraneoplastic syndrome: squamous cell carcioma

Answer 34

• Parathyroid hormone-related protein (PTH-rp) secretion leading to hypercalcaemia
• Ectopic thyroid-stimulating hormone secretion (TSH) leading to thyrotoxicosis

Question 35

Refer using a suspected cancer (2-week wait) pathway for lung cancer if:

Answer 35

• There are chest x-ray features that suggest lung cancer
• ≥40 years with unexplained haemoptysis

Question 36

when to offer x-ray

Answer 36

Offer an urgent chest x-ray within 2 weeks if patients have 2 or more of the following, or if they have ever smoked and have one of the following:

• Cough
• Fatigue
• Shortness of breath
• Chest pain
• Weight loss
• Appetite loss

Consider an urgent chest x-ray within 2 weeks if patients are ≥40 with any of the following:

• Persistent or recurrent chest infections
• Finger clubbing
• Supraclavicular or persistent cervical lymphadenopathy
• Chest signs suggestive of cancer
• Thrombocytosis – this can be a marker for potential cancers

Question 37

investigations for lung cancer

Answer 37

Chest x-rays:
* The first investigation performed on all patients with suspected lung cancer

CT chest with contrast:
* The investigation of choice for lung cancer
* The contrast helps differentiate lymph nodes from blood vessels

Bronchoscopy:
* To allow a biopsy to be taken for histological diagnosis
* Positron emission tomography (PET)-

CT scan:
* Done in potentially curable patients to localise pathology

Bloods
- FBC- thrombocytosis
- LFT- mets
- UEs- hyponatraemia due to SIADH

Bone scan
- mets

CT or MRI or brain
- brain metastasis

Question 38

management of lung cancer

Answer 38

Management options are put in place using a multidisciplinary approach. In NSCLC, surgery may be an option, along with radiotherapy and chemotherapy. Many patients with SCLC, however, have metastases at the time of presentation, and are less suitable for surgery, leaving chemotherapy and radiotherapy as treatment options.

Treatments such as endobronchial stenting and debulking can be used in palliative care to relieve bronchial obstruction.

Question 39

Mesothelioma

Answer 39

• Mesothelioma is a cancer that develops from the mesothelial lining of the lungs and is strongly associated with asbestos exposure.
• Other less common sites that can be affected are the lining of the abdomen, the pericardium, or the tunica vaginalis surrounding the testes.

Question 40

Asbestos-Related Lung Diseases

Answer 40

Asbestos is a fibre-like material that was once used in insulating buildings. Its use has been fully banned since 1999. People exposed to asbestos often develop lung disease, and the risk of developing asbestos-related diseases increases with the duration and degree of exposure.

Asbestos exposure can lead to the development of:

Benign diseases:
* Pleural plaques – most common
* Pleural thickening

Interstitial lung disease:
* Asbestosis – usually causes lower lobe fibrosis

Malignant disease:
* Mesothelioma
* Lung cancer

Question 41

RF mesothelioma

Answer 41

• Asbestos exposure
• Age >75 years – this is because the latency period between asbestos exposure and the development of mesothelioma is around 20-40 years, so most patients are older adults

Question 42

presentation of mesothelioma

Answer 42

Mesothelioma should be suspected in a patient with new painless pleural effusions, especially if they have chest pain or a history of asbestos exposure. Patients may have:

• Progressively worsening shortness of breath
• Chest pain:
• Cough: usually dry
• Constitutional symptoms: These are fevers, night sweats, weight loss, and fatigue
• Reduced breath sounds on examination:
• Usually due to pleural effusions or obstruction
• Dullness to percussion on examination:
• Usually due to pleural effusions

Question 43

Investigations for mesothelioma

Answer 43

Chest x-ray:
* May show pleural effusions or pleural thickening
* There may also be signs of asbestos exposure e.g. lower zone lung fibrosis

CT chest with contrast:
* More sensitive for identifying mesothelioma

Pleural fluid analysis:
* If a pleural effusion is present, the fluid should be sent for microscopy, culture and sensitivities, biochemistry, and cytology

Pleural biopsy via thoracoscopy
- Allows for histological diagnosis