8 - COPD

Question 1

What is COPD?

Answer 1

airflow limitation that is not fully reversible. It encompasses emphysema and chronic bronchitis. Abnormal inflammatory response of the lungs to noxious particles or gases

Question 2

what is the aetiology of COPD?

Answer 2

smoking (90%), air pollution and occupational exposure

alpha-1-antitrypsin deficiency (inherited condition that is a less common cause)

Question 3

what are the pathological changes seen in COPD?

Answer 3

• enlargement of the mucus secreting glands of the central airways
• increased number of goblet cells
• ciliary dysfunction
• breakdown of elastin leading to destruction of the alveolar walls and structure and loss of elastic recoil
• formation of large air spaces with reduction in total surface area available for gas exchange
• vascular bed changes causing pulmonary hypertension

Question 4

what is emphysema?

Answer 4

a subtype of COPD
elastin breakdown with loss of alveolar integrity causing permanent destructive enlargement of the airspaces distal to the terminal bronchioles

Question 5

what is chronic bronchitis?

Answer 5

a subtype of COPD

excessive mucus secretion and impaired removal of the secretions (due to ciliary dysfunction)

Question 6

what are the changes that occur that lead to airway resistance?

Answer 6

a) luminal obstruction of the airways by secretions
b) narrowing of small bronchioles - which are usually kept open by outward pull exerted on their walls by elastin surrounding the alveoli
c) decreased elastic recoil - so reduced expiratory force so air trapping

Question 7

what does airway narrowing and destruction of lung parenchyma predispose COPD patients to and what conditions can occur as a result?

Answer 7

hypoxia

progressive hypoxia causes pulmonary vasoconstriction and vascular smooth muscle thickening with subsequent pulmonary hypertension and right heart failure (Cor pulmonale)

Question 8

what are the (early) clinical features of the disease?

Answer 8

• COUGH
  usually initial symptom, frequently in the morning, productive
• SHORTNESS OF BREATH
  usually on exertion
• TACHYPNOEA
  increased RR due to hypoxia and hypoventilation
• USE OF ACCESSORY MUSCLES OF RESPIRATION
• BARREL CHEST
  due to hyperinflation and air trapping due to incomplete expiration
• HYPER-RESONANCE ON PERCUSSION
  due to hyperinflation and air trapping
• REDUCED INTENSITY (DISTANT) BREATH SOUNDS
  barrel chest, hyperinflation and air trapping
• REDUCED AIR ENTRY (POOR AIR MOVEMENT)
  secondary to loss of lung elasticity and lung tissue breakdown
• WHEEZING

Question 9

what are the accessory muscles of inspiration?

Answer 9

SCM
scalene
serratus anterior
pec major

Question 10

what are the accessory muscles of expiration?

Answer 10

internal intercostals

abdominal wall muscles (external + internal oblique and rectus abdomonis)

Question 11

what are the (late) clinical features of the disease?

Answer 11

CENTRAL CYANOSIS
hypoxia due to respiratory failure

FLAPPING TEMORS
due to co2 retention

SIGNS OF RIGHT SIDED HEART FAILURE
(distended neck veins, hepatomegaly, ankle oedema) secondary to pulmonary hypertension

Question 12

what investigations are done to diagnose COPD?

Answer 12

LUNG FUNCTION TESTS:

• OBSTRUCTIVE SPIROMETRY
• REDUCED DIFFUSING CAPACITY OF THE LUNG FOR CARBON MONOXIDE (emphysema)

CXR

PULSE OXIMETRY / ABG ANALYSIS

ALPHA 1 ANTITRYPSIN LEVEL

Question 13

What do the lung function tests show?

Answer 13

spirometry:

• obstructive
• FEV1/FVC ratio < 70%
• limited reversibility following treatment with bronchodilators
• time plot graphs and flow volume loops show obstructive pattern

Question 14

what does a CXR show?

Answer 14

as lungs are hyperinflated:

a) flattened diaphragm
b) hyperlucent lungs
c) increased antero-posterior diameter of chest

complications may be seen: pneumonia, pneumothorax

Question 15

what does pulse oximetry and ABG show?

Answer 15

done in acutely unwell - assess for hypoxia and hypercapnia

screen for those that need home oxygen therapy

Question 16

is sputum or blood eosinophilia suggestive of asthma or COPD?

Answer 16

asthma

Question 17

how does asthma differ from COPD?

Answer 17

asthma:
- onset is early
personal or family history, allergy, rhinitis, eczema, daily variability, responds to bronchodilators

Question 18

what are the treatments of COPD?

Answer 18

smoking cessation
patient education
pneumococcal vaccination
monitor weight, nutrition status and physical activity
bronchodilators
inhaled corticosteroids
pulmonary rehabilitation (patients often dont exercise as it makes them breathless)
long term oxygen treatment - low dose o2/ 16 hours a day
surgical intervention - removal of bullae, lung volume reduction + lung transplant

Question 19

what is an acute exacerbation of COPD?

Answer 19

• a change in the patient’s baseline dysponea, cough and or sputum that is beyond normal day-to-day variations and acute in onset

acute infectious exacerbations : acute, severe SOB, fever and chest pain

Question 20

what is the management of acute exacerbation of COPD?

Answer 20

• monitor for hypoxia and hypercapnia - pulse oximetry and ABG
• Abx for haemophilus influenzae and streptococcus pneumoniae (co-amox)
• nebulised bronchodilators
• oral steroids (high dose pred)
• 24% or 28% oxygen therapy while keeping under review for co2 retention
• consider non-invasive ventilation for worsening type 2 respiratory failure

Question 21

what are the complications of COPD?

Answer 21

• recurrent pneumonia
• pneumothorax (sub bulla formation and rupture)
• respiratory failure
• cor pulmonale (right heart failure)