L22 Interstitial Lung Disease

Question 1

Common end result of Interstitial lung diseases?

Answer 1

Common end result:

– damaged lung

– walls of the alveoli become inflamed

– scarring (or fibrosis) begins in the interstitium (tissue between the alveoli)

– lung becomes “stiff”

Question 2

Restrictive Lung Disease Spirometry Results

Answer 2

Question 3

Interstitial Lung Disease Clinical Presentation

Answer 3

Question 4

Investigations for Interstitial Lung Disease

Answer 4

GOOD HISTORY ESSENTIAL: environmental exposures common

Broncho Alveolar Lavage:

Interstitial Lung Disease:

Increased Neutrophil Count

Increased Lymphocytes

Increased Eosinophils

Transbronchial biopsy (TBBx)

• Histology of lung tissue (not recommended as a diagnostic tool)
• Helpful to exclude – sarcoidosis (granulomas), infection, neoplasms
• Role in the diagnosis of

– cryptogenic organising pneumonia

– acute interstitial pneumonitis

– Hypersensitivity pneumonitis

Open lung biopsy

• Larger fragments** of lung from **multiple lobes
• Better sampling
• Overall better architecture assessment

Question 5

Idiopathic Pulmonary Fibrosis

Characteristics?

Clinical Course?

Answer 5

Characteristics:

>50 yo, M>F

Worsening Dyspnea, Basal End-INspiratory Crackles at ausultation

RESTRICTIVE pattern

Increase in Neutrophils

Usual Interstitial Pneumonia Pattern on Histopathology (HONEYCOMB CHANGES and GROUND GLASS OPASCITIES)

Clinical Course:

Ultimately fatal: Mean survival 2.5-3.5 years

Antifibrotic drugs slow disease progression, transplantation needed

RIght heart failure and increased risk of cancer

Question 6

Non-Specific Interstitial Pneumonia (NSIP)

Characteristics?

Clinical Course?

Answer 6

Characteristics:

Mean age 10 years younger than Idiopathic Pulmonary Fibrosis, can occur in children

Breathless, cough, weight loss

LESS clubbing than IPF

Inspiratory Crackles and Squeaks

Clinical Course:

prognosis depends on extent of fibrosis

Can recover or relapse, minority die of respiratory fialure

Question 7

Adult Respiratory Distress Syndrome (ARDS)

Common Causes?

Pathology?

Clinical Presentation?

Answer 7

Common Causes: Shock, Trauma, Infection/Sepsis

Pathology: Acute Interstitial Pneumonitis

NOT associated with smoking

Mean Age 50y/o M=F

Clinical Presentation?

Respiratory Distress

Dyspnea, Fever, Malaise, Arthralgias, Diffuse Crackles

Hypoxemic

Reduced lung compliance

40% die within first few days, survivors mostly progress to full recovery

Question 7

Causes of Hypersentisitivty Pneumonitis (aka. Extrinsic Allergic Alveolitis)?

Answer 7

Granulomatous lung disease

Avian Proteins (Brid Fancier’s Lung)

Moldy Hay (Farmer’s Lung)

Crack Cocaine (Crack Lung)

Mycobacterium Avium intracellulare (Hot Tub Lung)

Question 8

Threshold ABG of Respiratory Failure?

Answer 8

diagnosis on ABG’s (arterial blood gases) and clinical features

Oxygenation

• PaO2 ≤ 60 mm Hg (room air)
• Refractory to O2 supplementation

Carbon dioxide elimination

• PaCO2 >50 mm Hg
• Responds to O2 supplementation

Question 9

Type I versus type II respiratory failure?

Answer 9

Hypoxemic respiratory failure (type I)- most common form of respiratory failure

PaO2 ≤ 60 mm Hg – Failure to exchange oxygen, refractory to O2 supplementation

normal or low PaCO2 – due to hyperventilation to compensate for hypoxemia

Causes:

collapse: pneumothorax, atelectasis

“flooding”

• oedema (cardiogenic or non-cardiogenic/ARDS)
• pneumonia (pus)
• pulmonary haemorrhage (blood)
• aspiration pneumonia

pulmonary fibrosis- ILD

pulmonary embolism

pulmonary hypertension

Hypercapnic respiratory failure (type II)

PaCO2 >50 mm Hg – Failure to remove carbon dioxide

Low O2 (on room air)- Responds to O2 supplementation

Causes

• drug overdose

• neuromuscular diseases

• chest wall abnormalities

• severe airway disorders – asthma, COPD

Question 10

Interstitial Lunge disease usually causes a __________ defect

Answer 10

Interstitial Lung disease usually causes a RESTRICTIVE defect