Case 3 - restrictive lung disease

Question 1

What is a restrictive lung disease?

Answer 1

Restrictive lung disease is where the lung or chest wall are restricted from moving.
Restrictive lung disease can be divided into Pulmonary (inside the lungs) and Extra-pulmonary (outside the lungs).

Question 2

the following restrictive lung diseases all have what in common:
Pneumonia
Pneumothorax
Atelectasis (partial collapse or closure of a lung)
Pulmonary fibrosis

Answer 2

Loss of volume, Increased recoil of lung

Question 3

the following restrictive lung diseases all have what in common:
Pleural thickening
Neuromuscular weakness

Answer 3

Difficulty in production of Chest Movements

Question 4

the following restrictive lung diseases all have what in common:
Ankylosing spondylitis
Kyphoscoliosis
Obesity

Answer 4

External mechanical limitation of lung volume

Question 5

what is The lung interstitium?

Answer 5

The lung interstitium is the thin, supportive tissue that lies between the alveoli
in the lungs.
It forms a framework that provides structure to the lungs and contains
blood vessels, lymphatic vessels, and connective tissue.

Question 6

what are the Structural Cells of the interstitium and their functions?

Answer 6

1.Fibroblasts – Produce collagen, elastin and ground substance
2.Myofibroblasts – Wound healing and fibrosis; excess activation can lead to
pulmonary fibrosis.
3.Endothelial Cells – Lines the pulmonary capillaries
4.Pericytes – Support capillaries, regulate blood flow, and contribute to tissue repair.

Question 7

what are the Immune and Inflammatory Cells of the interstitium?

Answer 7

Macrophages
Mast Cells
Dendritic Cells
Lymphocytes (T and B cells)

Question 8

classical functions of macrophages and dendritic cells?

Answer 8

Common functions of both macrophages and dendritic cells:
phagocytosis
chemokine/cytokine production
tissue surveillance

Functions of macrophages only:
cytotoxicity
fibrosis

Functions of dendritic cells only:
antigen presentation
T-cell activation

Question 9

Most Interstitial lung diseases are associated with extensive destruction and alteration of:

Answer 9

Alveoli
Airway architecture
Vasculature

Question 10

Effects of inflammation and fibrosis

Answer 10

Leads to temporary or permanent changes in the interstitial tissues

The lung parenchyma (area of the lung where gas exchange takes place, e,g alveoli, interstitial tissues, fibres) becomes stiff and thickened

The development of fibrous tissue in the interstitium makes the lungs less compliant (harder to expand and stretch with changes in pressure) and harder to inflate

Consequently, the work of breathing is increased

Inflammation and fibrosis → interferes with diffusion of gases & changes the mechanics of breathing

Question 11

what is compliance on a curve (graph of volume against pressure around lung)

Answer 11

Compliance is the change in volume per
unit pressure: represents the slope of
the curve

Question 12

when is compliance reduced?

Answer 12

• Increase of fibrous tissue in the lung
  (pulmonary fibrosis)
• Collapse/closure of lung (Atelectasis)
• Increase in pulmonary venous pressure

Question 13

when is compliance increased?

Answer 13

Emphysema

Question 14

regarding Compliance =Volume /Pressure, what is emphysema and fibrosis?

Answer 14

Emphysema: same amount of pressure, easier to inflate.

Fibrosis: same amount of pressure, harder to inflate

Question 15

what is drug induced pulmonary fibrosis caused by?

Answer 15

prior or current use of amiodarone, nitrofurantoin, chemotherapy, methotrextate, or other drugs known to affect the lungs

Question 16

what is radiation induced pulmonary fibrosis caused by?

Answer 16

prior or current radiation treatment to the chest

Question 17

what is environmental pulmonary fibrosis (called hypersensitivity pneumonitis) caused by?

Answer 17

exposure to mold, animals or other triggers

Question 18

what is autoimmune pulmonary fibrosis (called connective tissue disease-related [PF]) caused by?

Answer 18

joint inflammation, skin changes (particularly on fingers and face), dry eyes or mouth, abnormal blood tests

Question 19

what is occupational pulmonary fibrosis (called pneumoconiosis) caused by?

Answer 19

prior or current exposure to dusts, fibres, fumes, or vapours that can cause PF (such as asbestos, coal, silica and others)

Question 20

pathology of idiopathic pulmonary fibrosis

Answer 20

pathology of idiopathic pulmonary fibrosis is characterised by thickening of the interstitium.
The interstitium becomes infiltrated by lymphocytes.
Fibroblasts lay down collagen.
Lung architecture becomes destroyed leading to multiple air-filled cystic spaces.

Question 21

Clinical features of idiopathic pulmonary fibrosis (NICE guidelines)

Answer 21

Age over 45 years
Persistent breathlessness on exertion
(dyspnoea)
Persistent (dry) cough
Bilateral inspiratory crackles when listening
to the chest (velcro tearing)
Clubbing of the fingers
Normal spirometry or impaired spirometry
usually with a restrictive pattern
Cyanosis at fingertips (investigate with
pulse oximetry)
Rapid shallow breathing

Question 22

Diagnosis of idiopathic pulmonary fibrosis

Answer 22

Take a detailed history of the patient, carrying out a clinical examination and perform blood
tests to help exclude alternative diagnoses (such as lung diseases associated with environmental and occupational exposure, with connective tissue diseases and with drugs.)

perform lung function testing - spirometry and gas transfer
do a chest x-ray and a CT scan of the thorax
high resolution chest x-ray to confirm pulmonary fibrosis

Question 23

what happens in Kyphoscoliosis

Answer 23

total respiratory and lung elastance and lung
resistance are increased

There is greater lung elastic recoil and
reduced compliance of the chest wall

Question 24

how is Kyphoscoliotics breathing largely
maintained

Answer 24

largely maintained through increased central
drive, and compensatory mechanisms including the Hering Breuer reflex (preventing over inflation) and increasing inspiratory
duration.

Question 25

The pleural fluid prevents the lungs from?

Answer 25

prevents the lungs from collapsing as a result of a negative pressure. [We have around 10-20ml of pleural fluid, it has very little protein and behaves as a lubricant.]

Question 26

what is Pleural effusion

Answer 26

the abnormal accumulation of fluid in the extravascular compartments of the lung as interstitial fluid

Question 27

what does pleural effusion prevent?

Answer 27

prevents lung movement by making the lung tissue stiff and less compliant. The fluid accumulation reduces gas transfer

Question 28

what about The neuromuscular control of respiration, focusing on the extra-pulmonary (outside the lungs) nervous system structures that influence breathing

Answer 28

There are corticospinal tract fibres that descend from the primary motor cortex to the brainstem respiratory groups and directly to peripheral motor nerve cell bodies in C3-C5. # These cell bodies are located in the ventral horn of the spinal cord. The nerve stimulated is the phrenic nerve which innervates the diaphragm. The intercostal nerves have cell bodies that lie in T1-T11.

Question 29

FEV1 and FVC in restrictive lung disease

Answer 29

In restrictive lung disease, both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced, however, the decline in FVC is more than that of FEV1, resulting in a higher than 70% FEV1/FVC ratio.

Question 30

Flow-volume loops in restrictive lung disease

Answer 30

the loop shifts to the Right ( is narrowed and smaller) -> This means that there is a decrease in Total Lung Capacity, Functional residual capacity and Residual Volume. There is a normal or high FEV1/FVC ratio because both are reduced by equal amounts although both are lower than normal -> so FEV1/FVC is typically >0.7

Question 31

Flow-Volume loops are ____and _____in restrictive lung disease

Answer 31

Flow-Volume loops are tall and narrow in restrictive lung disease

Question 32

what is the most common extra-pulmonary restrictive disease

Answer 32

Obesity

Question 33

how does obesity affect the respiratory system

Answer 33

through increased metabolic demands during daily activities and through restriction of the chest wall and reduced movement of the diaphragm

Question 34

what syndromes is obesity associated with (2 syndromes)

Answer 34

It is associated with: 1. obesity hypoventilation syndrome and 2. obstructive sleep apnoea syndrome

Question 35

what about the airways and airway smooth muscle changes that happen in obesity

Answer 35

obesity has reduced airway diameter and altered airway smooth muscle structure and function

Question 36

define hypercapnia

Answer 36

Hypercapnia is a medical term that means elevated levels of carbon dioxide (CO₂) in the blood.

Question 37

Obstructive Sleep Apnea

Answer 37

In most cases of sleep apnea the muscles of the throat relax too much and obstruct the airway. Normally the person will wake up after a minute or so of sleep in an agitated state due to build up of carbon dioxide during the apnea. Chronic apneoa can lead to desensitision of the central chemoreceptors to carbon dioxide. This in turn can lead to “happy hypoxia”. This is ‘Ondine’s Curse’

Question 38

Investigations of Obstructive Sleep Apnea shows (name 2)

Answer 38

Investigation shows tonsillar hypertrophy, macroglossia, retrognathia (overbite)

Question 39

Common physical abnormal findings of Obstructive Sleep Apnea (name 2)

Answer 39

non-specific narrowing of the oropharyngeal airway with or without soft tissue disposition

Question 40

how is Obstructive Sleep Apnea assessed

Answer 40

Assessed with sleep device (polysomnography): oxygen and carbon dioxide monitoring and less intrusively using questionnaires such as the Epworth Sleepiness Scale

Question 41

Treatment of Obstructive Sleep Apnea

Answer 41

CPAP (Continuous positive airway pressure)

Question 42

(OSAS) obstructive Sleep Apnea Syndrome is characterised by?

Answer 42

the co-existence of excessive day time sleepiness with irregular breathing at night recurring episodes of upper airway (UA) obstruction that leads to markedly reduced (hypocapnoea) or absent (apnoea) airflow at the nose/mouth -> this can result in sleep fragmentation and diminished amounts of slow-wave and rapid eye movement (REM) sleep

Question 43

Hypocapnoea

Answer 43

low levels of carbon dioxide (CO₂) in the blood, specifically in arterial blood.

Question 44

clinical features at night of Obstructive Sleep Apnea Syndrome - name 2

Answer 44

snoring witnessed apnoeas nocturnal choking restless sleep insomnia recurrent awakenings nocturia heartburn reduced libido sweating cardiac arrhythmias

Question 45

clinical features at daytime of Obstructive Sleep Apnea Syndrome - name 2

Answer 45

excessive daytime sleepiness fatigue memory impairment poor concentration intellectual deterioration/personality changes morning headaches and nausea depression

Question 46

Why are the lungs smaller than normal during inspiration in idiopathic pulmonary fibrosis?

Answer 46

Because of scarring (fibrosis) in the lung interstitium, which leads to: decreased lung compliance - lung tissue becomes stiff and fibrotic, the stiffness means that the lungs don't expand as easily when you inhale and so during inspiration less air enters lungs → making the inspired lung volumes smaller than normal)

Question 47

A 55 year old woman goes to the GP with a 5-year history of breathlessness and a persistent cough. The clinical examination reveals bilateral inspiratory crackles. She is referred for spirometry which shows impaired lung function with a restrictive pattern. Normal X-ray of the chest is inconclusive. Pulmonary fibrosis is suspected. What is the most appropriate next test to assess the patient for pulmonary fibrosis?

Answer 47

High resolution CT of chest