RESPIRATORY MEDICINE

Question 1

Describe Maintenance and Reliever Therapy (MART)?

Answer 1

A form of combined ICS and LABA treatment in which a single inhaler containing both ICS and fast-acting LABA for daily maintenance therapy and the relief of symptoms required
MART is only available for ICS and LABA combos in which LABA has a fast-acting component- FORMOTEROL

Question 2

Describe Acute Respiratory Distress Syndrome (ARDS)?

Answer 2

Alveolar capillaries become more permeable>leading to fluid accumulation in the alveoli> non-cardiogenic pulmonary oedema
Pathophysioloigcal mechanism: pro-inflammatory cytokines and chemokines as well as neutrophillic infilatraion
Commonest finding in ARDS: hypoxaemic respiratory failure» clinical presentation: **acute-onset cyanosis, dyspnoea and tachypnoea **

Question 3

Asthma

7 year old girl who is known asthmatic- decreased chest expanision, wheeze biliaterally on auscultation, heart rate is 130, RR- 36, BP-110/80. Sats: 84%, unable to complete sentences- what sign is a life threatening asthma attack?

Answer 3

O2 sats of 84%- according to BTS/SIGN/ management of acute asthma in children- only sats <92% qualify as life threatening asthma> other life threatening features:
PEF <33%,
Silent Chest
Hypotension
Exhaustion
Confusion
Poor resp effort

Question 4

Pleural Effusion

Define Pleural Effusion and give symptoms and signs?

Answer 4

Definition: A pleural effusion is characterized by the abnormal accumulation of fluid within the pleural cavity> **primary treatment goal is to alleviate any associated respiratory distress **and address the underlying causative factor

Symptoms:
General symptoms relating to the effusion itself include: DPR

Dyspnoea
Reduced exercise tolerance
Pleuritic chest pain

Signs:
While examining the patient, it is important to look for underlying clues as to the aetiology of the effusion, such as:

Pyrexia – suggestive of infection
Cachexia and clubbing – suggestive of malignancy
Raised JVP and ankle oedema – suggestive of heart failure
On general inspection:

The patient may be in respiratory distress, with tachypnoea and cyanosis

Scars may be visible from previous thoracic surgeries or previous chest drains

In very large effusions, the trachea may be deviated away from the affected side

Chest expansion may be reduced on the affected side

Lymphadenopathy may be present – indicating either infection or malignancy

Traditionally a ‘stony dull’ percussion note is found on the affected side

On auscultation:

There are reduced/absent breath sounds over the effusion
There may be bronchial breathing at the upper border of the pleural effusion
Vocal resonance/tactile vocal fremitus is reduced over the effusion

Question 5

Pleural Effusion

What are the causes of pleural effusions and describe Exudative and Transudative?

Answer 5

**Causes of pleural effusions are mainly divided into:

Exudative (protein content >35 g/l)
Transudative (protein content <35 g/l)
It is important to differentiate whether there is a unilateral effusion or bilateral effusions.

Note: transudative pleural effusions are more likely to be bilateral; exudative pleural effusions are more likely to be unilateral

Exudative
Exudative pleural effusions are caused by diseases that increase capillary permeability, examples include:

• Infections – pneumonia or TB (ie. parapneumonic effusion)
• Malignancy – bronchial carcinoma, mesothelioma or lung metastases
• Inflammatory conditions – rheumatoid arthritis, lupus or acute pancreatitis
• Pulmonary infarction – secondary to a pulmonary embolism or following trauma
• Chylothorax
• Oesophageal perforation

Transudative
Transudative pleural effusions are caused by **imbalance **in the Starling forces that govern the formation of interstitial fluid and include conditions that:

increase the capillary hydrostatic pressure – forcing fluid out of the pulmonary capillaries into the pleural space (eg. congestive cardiac failure)
reduce the capillary oncotic pressure – impairing the reabsorption of fluid from the pleural space into the pulmonary capillaries (eg. cirrhosis, nephrotic syndrome/chronic kidney disease, and gastrointestinal malabsorption/malnutrition as seen in coeliac disease)
Less common causes of transudative pleural effusions include hypothyroidism and Meig syndrome (the triad of ascites, pleural effusion and benign ovarian tumour).

Chylothorax
Collection of lymph fluid in the pleural space
Usually secondary to trauma to the lymphatic system (ie. penetrating chest injury or cardiothoracic surgery)
Tip: if there is a unilateral effusion and recent sternotomy scar, think chylothorax.

Question 6

Pleural Effusion

Describe the following investigations for Pleural Effusion?
History, Blood and Imaging

Answer 6

History: timeline of symptoms developing

whether there is

a systemic disease (eg. rheumatoid arthritis)
weight loss or cough
global fluid overload
immunocompromise or TB exposure
drug history – some** drugs have been shown to cause exudative pleural effusions (eg. methotrexate, phenytoin, amiodarone)**

Blood tests
FBC – may show a raised WCC suggestive of infection
U&E – may show a raised creatinine suggestive of renal impairment
LFTs – may show a low albumin and raised alanine aminotransferase (ALT)/aspartate aminotransferase (AST) suggestive of cirrhosis
Clotting – to indicate safety for pleural intervention

Imaging:
Chest X-ray is the first-line imaging investigation in all patients with a suspected pleural effusion»will reveal blunting of the costophrenic angle or white-out of lung (if large)

Thoracic ultrasound- can reveal whether it is simple fluid or septated, which would be consistent with malignancy or infection

underlying changes in the lung can also be identified– such as consolidation or pulmonary oedema.

CT scan with contrast- can be useful to identify pleural thickening and indicate whether this is likely to be benign or malignant

Question 7

Pleural Effusion

Describe the following investigation for Pleural Effusion?
Pleural Fluid Sampling:

Answer 7

Must be performed under ULTRASOUND GUIDANCE (high complication rate)
Diagnostic Pleural Tap:
In the context of a unilateral-exudative effusion
Suspected Transudative or Bilateral Effusions: should not be sampled unless atypical features/failure to respond to treatment

Pleural Fluid:
Biochemistry- Protein Level, LDH, Glucose, Amylase
Cytology
Microbiology- Grain stain/culture
To aid diagnosis:Glucose (low in RA and Empyema)
pH= <7.2 in empyema
Amylase- raised in pancreatitis
Cholesterol and Triglycerides: raised in Chylothorax
Immunology: RF (if RA is suspected)
ANA (SLE)
Complement: low in Pleural Effusions caused by RA or SLE

											Exudative Pleural Effusion-protein content >35g/L
											Transudative protein content <35g/L
											If protein content id equivocak (25-35)- LIGHTS CRITERIA applied:
											
										Effusion is an exudate if: 
										Pleural Fluid to Serum Protein ratio is >0.5
										Pleural Fluid to Serum LDH ratio is >0.6 or 
										Pleural Fluid LDH is >2/3 the upper limit for serum LDH

Pleural Biopsy: suspicion of malignancy and pleural nodularity seen on CT

Question 8

Pleural Effusion

Describe the management of Pleural Effusion?

Answer 8

• Underlying cause should be treated and patient managed in A-E approach:
  * appropriate oxygen therapy
  * attempts to reduce tesp distress medically: diuretics for HF or antibiotics for chest infections
• US- guided pleural aspiration- if above fails or patients rwmains symptomatic
• Other mangagements:
  * intercostal drain: large Pleural effusions/empyemas
  * Chemical pleurodesis- recurrent/persistent effusions» injection/irritant through chest drain>cause fibrotic reaction in pleura> aim to seal potential pleural space
  * tunnelled indwelling pleural catheter> allow regular drainage of recurrent fluid» helpful in palliative patients

Question 9

What is the immediate management for a Tension Pneumothorax?

Answer 9

Medical Emergency: requires immediate DECOMPRESSION with a 14-16 guage cannula into the right/left 5th intercostal space, mid-axillary line if the cause is Trauma however in tension pneumothorax a needle decompressiom with a 16-guage cannula in the 2nd intercostal space-mid clavicular line of affected side- the needle should be just above 3rd rib to avoid neurovascular bundle

Question 10

Idiopathic Pulmonary Fibrosis

WHo is at risk for IPF?

Answer 10

Patients aged 50-70 years and is 2x as common in men

Question 11

Idiopathic Pulmonary Fibrosis

Describe the clinical features of IPF?

Answer 11

Features:
progressive** exertional dyspnoea**
bibasal fine end-inspiratory crepitations on auscultation
dry cough
clubbing

Question 12

Idiopathic Pulmonary Fibrosis

Describe the diagnosis investigations for IPF?

Answer 12

1. Spirometry> restrictive pattern (FEV1-normal/decreased and FVC decreased, and FEV1/FVC is increased)
2. impaired gas exchange- reduced transfer factor-TLCO
3. Imaging: bilateral interstitial shadowing- small irregular peripheral opacitiies-ground glass-later progressing to honeycombing

Question 13

Idiopathic Pulmonary Fibrosis

Name the investigation of choice required to make a diagnosis of IPF?

Answer 13

High resolution CT Scanning

Question 14

Idiopathic Pulmonary Fibrosis

Describe the management and prognosis of IPF?

Answer 14

1. Pulmonary Rehab
2. Selected patients: Pirfenidone (antifibrotic agent)
3. Supplementary O2 and eventually lung transplant
   Prognosis: Poor, average life expectancy: 3-4 yrs

Question 15

TB

What can be seen on C-Xray with TB?

Answer 15

Upper zone pulmonary fibrosis

Question 16

TB

Descibe the diagnosis of secondary TB?

Answer 16

african descent
reactivation of latent TB due to AZATHIOPRINE-INDUCED immune suppression
confirmed by Ziehl Neelsen stain: presence of acid-fast organism (mycobacterium TB)
TB- typically caused upper zone fibrosis-as bacteria most commonly reside in upper lung zones due to effects of gravity on alveolar ventilation:perfusion ratio, O2 availability is highest in this area