Respiratory Investigations

Question 1

What investigations do you do for a suspected pulmonary embolism and what are the results

Answer 1

D dimer test >4 (Wells’ criteria)

ABG (hypoxia - ↓ RV output and hypocapnia - hyperventilation)

Question 2

What is a saddle emboli and what imaging technique is used to pick it up?

Answer 2

Emboli at the bifurcation of the pulmonary trunk and use CTPA (CT Pulmonary Angiography)

Question 3

What is a lung lobar collapse and what 4 signs will be present on a CXR?

Answer 3

A subtype of atelectasis where is single lung lobe collapses

• Sail sign (blunt heart angle)
• Hemidiaphragm at the side of the atelectasis rises
• Mediastinal shift to the side of atelectasis due to decreased pressure/volume
• Crowding of ribs on ipsilateral side

Question 4

What is the triad of signs on the CXR for a pneumothorax

Answer 4

On side with pathology:
Hyper-lucent
Loss of lung markings
Edge of collapsed lung

Question 5

What pleural effusion has ↑pleural protein: ↓serum protein (≥0.5)?

Why?

Answer 5

Exudate

Due to increased permeability of the parietal capillaries as a result of inflammation leading to damage of the capillary wall

Question 6

How would you diagnose a pleural effusion on a CXR?

Answer 6

Dense, homogenous opacity in lower zone that blurs out diaphragm. Meniscus in upper zone

Question 7

What is pulmonary oedema?

And what are its 5 signs on a CXR?

Answer 7

Excess fluid in the small air sacs

A - Alveolar oedema
B - Kerley B lines
C - cardiomegaly
D - dilated prominent upper lobe vessels
E - pleural effusion

Question 8

What is the Bat wing sign in pulmonary oedema?

Answer 8

Alveolar oedema

Question 9

What are the Kerley B lines in pulmonary oedema?

Answer 9

Interstitial oedema

Question 10

Describe a caseating granuloma typical of tuberculosis

Answer 10

Epithelioid histocytes (modified, immobile macrophages)
Central caseous necrosis
Giant cell (Langhans)
Lymphocytes

Question 11

What tests do you do to identify a latent dead tuberculosis infection?

Answer 11

Interferon gamma test or a tuberculin skin test

Question 12

What tests do you do to identify a latent dormant/active tuberculosis infection?

How can you differentiate between both tests?

What further test can you do to help you with treatment of one of the forms of tuberculosis’ discussed above?

Answer 12

Sputum smear with Ziehl-Neelsen method - turn pink
Latent dormant TB: - smear (<5000 bacilli)
Active TB: + smear (≥5000) then do NAAT to ID drug resistance mutations

Question 13

What are the tests used to diagnose COPD?

5

Answer 13

CXR
Spirometry
ABG
a1 anti-trypsin level
Pulse oximetry

Question 14

What are the characteristics of an obstructive respiratory disease on a flow volume loop spirometry graph

Answer 14

Peak of expiratory loop will be shorter
Scalloping of the descending line of the expiratory loop

Smaller inspiratory loop

Question 15

In an obstructive respiratory disease (COPD, Asthma), out of FEV1 and FVC, which one will be reduced and which one will be near normal?

And why?

Answer 15

FVC will be near normal because if give enough time they can breath the air out of the lungs

FEV1 will be reduced because there is an obstruction

Question 16

Why is the flow-volume loop of a restrictive lung disease patient narrower, taller, with a small vital capacity?

Answer 16

As the large airways are unable to expand (so less air can enter the lungs and less air can leave)

Question 17

What imaging technique is the best to diagnose bronchiectasis?

And what would you see on this image?

Answer 17

High resolution CT

• bronchus size>pulmonary artery
• bronchial dilation
• bronchial wall thickening
• signet ring sign

Question 18

What is the Signet ring sign on a CT scan in bronchiectasis?

Answer 18

Dilated bronchus with its accompanying pulmonary artery

Question 19

List 5 signs of bronchiectasis

Answer 19

Coarse crackles
Rhonchi
Haemoptysis
Fever
Clubbing

Question 20

What pair of sounds are heard with a patient that has bronchiectasis and COPD

Answer 20

Coarse crackles and wheezing

Question 21

What is the autosomal recessive gene mutation in cystic fibrosis?

Answer 21

Phe508del

Question 22

What is seen on an x ray of pulmonary fibrosis?

Answer 22

Diffuse interstitial markings

DIM

Question 23

What are 3 signs that could be heard on auscultation of a chest with Bronchiectasis (chronic/recurrent productive cough, esp. in a non-smoker)

Answer 23

1. Wheeze (34% of cases)
2. Large airway rhonchi (44% of cases)
3. Coarse crackles at lung bases during early inspiration (70% of cases)

Question 24

On a CXR, if the AP window is obscured, what can be 2 MAJOR reasons of this?

Answer 24

1. Enlarged mediastinal lymph nodes

2. Primary lung cancer

Question 25

In an obscured AP window in a CXR caused by enlarged mediastinal lymph nodes, name 3 conditions that can lead to enlarged mediastinal lymph nodes

Answer 25

1. Sarcoidosis
2. Lymphoma
3. TB

Question 26

Name a condition that causes a low Dlco.

What does Dlco stand for?

Answer 26

Diffusing capacity of carbon monoxide.

E.g.: Diffuse lung fibrosis

Question 27

Name a condition of a high diffusing capacity of carbon monoxide

Answer 27

Alveolar haemorrhage (leads to pulmonary blood volume increasing)

Question 28

Use MUDPILES to name possible causes of a high anion gap metabolic acidosis

Answer 28

Methanol
Uraemia
DKA
Paraldehyde
Isoniazid
Lactic acidosis
Ethylene glycol
Salicylates (Aspirin)