Respiratory Medicine

Question 1

What reduces pulmonary compliance? (2)

Answer 1

Pulmonary venous engorgement + alveolar oedema

Atelectasis

Question 2

Which cells release pulmonary surfactant?

Answer 2

Type 2 alveolar epithelial cells -> This lowers surface tension of the fluid lining the alveoli increasing lung compliance

Question 3

What causes respiratory distress syndrome?

Answer 3

Lack of surfactant

Question 4

Where does the greatest resistance to flow occur in the airways?

Answer 4

Medium-sized bronchi

Question 5

What can happen to small airways at low lung volumes? Where is most susceptible to this?

Answer 5

They can close completely which can lead to areas of atelectasis

This particularly occurs at the lung bases

Question 6

What is hypoxic vasoconstriction?

Answer 6

This is when vasoconstriction occurs in small arterioles of a hypoxic region of the lung

This helps divert blood away from areas of poor ventilation to ensure ventilation and perfusion is matched

Question 7

Where are central and peripheral chemoreceptors found? what do they respond to?

Answer 7

Central - Medulla (Increases in H+ in the CSF secondary to increased pCO2 in blood)

Peripheral - Carotid + aortic bodies (Low O2, High CO2 and pH changes)

Question 8

What is Cheyne-Strokes breathing?

Answer 8

Periods of apnoea followed by hyperventilation

Question 9

When does Cheyne-Strokes breathing occur? (3)

Answer 9

Severe heart failure

Severe brain damage

High altitudes

Question 10

What is the normal FEV1 : FVC ratio?

Answer 10

70-80%

Question 11

What conditions show reduced FEV1 with normal FVC (reduced ratio)?

Answer 11

Occurs in airway obstruction eg asthma and COPD

Question 12

What conditions show reduction in FVC with preserved FEV1 : FVC ratio?

Answer 12

Restrictive disease eg. pulmonary fibrosis, neuromuscular disease, obesity and pleural disease

Question 13

How can TLC, RV and FRC be measured? (3)

Answer 13

Helium dilution
Nitrogren washout
Body box

Question 14

What are the different causes of hypoxaemia? (7)

Answer 14

Hypoventilation (Opiate overdose, Respiratory muscle paralysis)

V / Q mismatch (PE)

Low inspired pO2 (High altitudes)

Impaired diffusion (Pulmonary oedema, interstitial lung disease)

Bronchiolar-alveolar cell carcinoma

Shunts (Pulmonary AV malformations, cardiac right to left)

Breathing in hypoxic mixtures

Question 15

What does right shift of the oxygen dissociation curve represent? What can trigger this? (4)

Answer 15

Right shift increases how easily O2 offloads in the tissues

Caused by high temp, acidosis, increase in pCO2 and increased 2,3-diphosphoglycerate (2,3-DPG)

Question 16

What does left shift of the oxygen dissociation curve represent? What can trigger this? (6)

Answer 16

O2 held on more closely by the Hb

Caused by low temp, alkalosis, decrease in pCO2, decrease in 2,3-diphosphoglycerate (2,3-DPG), COHb and fetal Hb

Question 17

What are some early responses to altitude of the body? (2)

Answer 17

Hyperventilation due to hypoxic stimulation of peripheral chemoreceptors

The subsequent resp alkalosis is corrected via renal excretion of bicarb

Question 18

What are some later changes in response to high altitude? (3)

Answer 18

Hypoxaemia -> EPO via kidneys -> polycythaemia thus incerased O2 carriage by blood

Increased 2,3-DPG production -> right shift of O2 dissocation curve -> better offloading to tissues

Hypoxic vasoconstriction -> increased pulmonary artery pressure -> RVH (nb. pulmonary HTN can be associated w/ pulmonary oedema - altitude sickness)

Question 19

Most important allergens responsible for asthma? (5)

Answer 19

House dust mite
Dog allergen
Cat allergen
Pollen
Grasses
Moulds

Question 20

Which drugs can trigger asthma attacks?

Answer 20

B-blockers

NSAIDs inc aspirin

Question 21

What are the features of early stages of asthma? (3)

Answer 21

Airways narrowed by a combination of:
1. Bronchiolar smooth muscle contraction
2. Mucosal oedema
3. Mucus plugging

In early stages, these changes are reversible

Question 22

What are the features of chronic asthma? (3)

Answer 22

Same features as early asthma however stuctural changes develop and lead to irreverisble fibrosis of airways

Structural changes:
1. Thickening of basement membrane
2. Goblet cell hyperplasia
3. Smooth muscle hypertrophy

Question 23

What causes sputum to be yellow / green in asthma?

Answer 23

Presence of eosinophils

Question 24

What are some features that suggest someone’s asthma may respond to steroids?

Answer 24

Sputum eosinophils >2 %

FENO >50 parts/billion

Question 24

What are some lung function tests that support asthma? (4)

Answer 24

Significant diurnal PEFR variability (>20%) for 3 or more days / week for 2 weeks Significant improvement in PEFR (>15%)+ FEV1 (400ml+) with bronchodilator / steroids Reduced FEV1 (Decreased FEV1:FVC ratio) Raised exhaled nitric oxide concentration (FENO)

Question 25

When should patient with acute asthma be referred to ICU? (7)

Answer 25

Worsening PEFR Persistent / worsening hypoxia Rising pCO2 Decreasing pH Exhaustion Altered conciousness Respiratory arrest

Question 25

Features of life threatening asthma? (10)

Answer 25

* Hypoxaemia * PEFR <33% of predicted * Exhaustion * Bradycardia (pulse <60 beats/min) or arrhythmmia * Hypotension * A silent chest * Altered consciousness * Poor respiratory effort * Cyanosis * A normal or raised PCO2.

Question 26

Discharge criteria for patient with asthma? (5)

Answer 26

* PEFR should be at least 75% of the patient’s best or predicted value * PEFR diurnal variability on monitoring should be <25% * The patient should have required no nebulised bronchodilators for at least 24 hours * The patient should have a written asthma action plan * The patient should have follow-up in primary or secondary care within 30 days of discharge

Question 27

What other respiratory condition do most patients with allergic bronchopulmonary aspergillosis have?

Answer 27

Asthma but can also occur in those without asthma

Question 28

What feature determines long term prognosis in those with COPD? What is a better way?

Answer 28

Post-bronchodilator FEV1 however this is poor in isolation BODE index (BMI, airflow obstruction, dyspnoea, exercise) - 7 or more is 31% 2y mortality

Question 29

Can COPD progress if the person stops smoking?

Answer 29

Yes

Question 30

Causes of COPD? (5)

Answer 30

* Smoking (usually a history of at least 20 pack-years) * Air pollution * Low birthweight and low socio economic status * Dust exposure * α1-Antitrypsin deficiency

Question 31

What is chronic bronchitis?

Answer 31

Chronic cough + sputum production for at least 3 months in 2 consecutive years in the absence of other causes

Question 32

What is emphysema?

Answer 32

Abnormal, permenant enlargement of airpaces distal to terminal bronchioles It is accompanied with destruction of their walls without obvious fibrosis

Question 33

What are the different types of emphysema? (4)

Answer 33

Centriacinar (affects upper lobes, associated w/ smoking) Panacinar (more common in a1-antitrypsin deficiency - whole acinus affected: alveoli, bronchioles + blood vessels) Paraseptal Scar emphysema (Localised around scars)

Question 34

What happens to DLCO in emphysema?

Answer 34

Reduced - which means reduced gas transfer

Question 35

How is COPD severity measured using FEV1? (4)

Answer 35

* Mild: FEV1 ≥80% predicted * Moderate: FEV1 50–79% predicted * Severe: FEV1 30–49% predicted * Very severe: FEV1 <30% predicted

Question 36

What are the signs of Cor pulmonale?

Answer 36

Raised JVP R Ventricular heave Loud P2 Tricuspid regurg Peripheral oedema Hepatomegaly

Question 37

Does adding inhaled steroids in addition to LA bronchodilators in COPD impact disease progression?

Answer 37

No

Question 38

Why are inhaled steroids used in COPD management alongside long-acting bronchodilators?

Answer 38

They reduce frequent of exacerbations and improve QoL in patients w/ severe or v. severe COPD

Question 39

Which patients with COPD can be considered for lung transplants?

Answer 39

Under 65 with FEV1 and DLCO <20% of predicted History of hospitalisation with exaccerbation associated with pulmonary hypertension +- cor pulmonale despite O2 therapy

Question 40

Which patients with COPD should be referred for pulmonary rehab? Why?

Answer 40

All motivated patients regardless of severity Increases exercise tolerance + improve QoL

Question 41

When are abx indicated in COPD exacerbations?

Answer 41

If 2 of the following are present: * Increased breathlessness * Increased sputum volume * Increased sputum purulence.

Question 42

What needs to be done in COPD exacerbation if hypercapnia and acidosis is present on inital ABG?

Answer 42

Treated as normal for hour Repeat ABG If acidosis with hypercapnia persists non-invasive positive pressure ventilation should be started via face mask