Flashcards in 8 - COPD Deck (21)
What is COPD?
airflow limitation that is not fully reversible. It encompasses emphysema and chronic bronchitis. Abnormal inflammatory response of the lungs to noxious particles or gases
what is the aetiology of COPD?
smoking (90%), air pollution and occupational exposure
alpha-1-antitrypsin deficiency (inherited condition that is a less common cause)
what are the pathological changes seen in COPD?
- 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
what is emphysema?
a subtype of COPD
elastin breakdown with loss of alveolar integrity causing permanent destructive enlargement of the airspaces distal to the terminal bronchioles
what is chronic bronchitis?
a subtype of COPD
excessive mucus secretion and impaired removal of the secretions (due to ciliary dysfunction)
what are the changes that occur that lead to airway resistance?
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
what does airway narrowing and destruction of lung parenchyma predispose COPD patients to and what conditions can occur as a result?
progressive hypoxia causes pulmonary vasoconstriction and vascular smooth muscle thickening with subsequent pulmonary hypertension and right heart failure (Cor pulmonale)
what are the (early) clinical features of the disease?
usually initial symptom, frequently in the morning, productive
- SHORTNESS OF BREATH
usually on exertion
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
what are the accessory muscles of inspiration?
what are the accessory muscles of expiration?
abdominal wall muscles (external + internal oblique and rectus abdomonis)
what are the (late) clinical features of the disease?
hypoxia due to respiratory failure
due to co2 retention
SIGNS OF RIGHT SIDED HEART FAILURE
(distended neck veins, hepatomegaly, ankle oedema) secondary to pulmonary hypertension
what investigations are done to diagnose COPD?
LUNG FUNCTION TESTS:
- OBSTRUCTIVE SPIROMETRY
- REDUCED DIFFUSING CAPACITY OF THE LUNG FOR CARBON MONOXIDE (emphysema)
PULSE OXIMETRY / ABG ANALYSIS
ALPHA 1 ANTITRYPSIN LEVEL
What do the lung function tests show?
- FEV1/FVC ratio < 70%
- limited reversibility following treatment with bronchodilators
- time plot graphs and flow volume loops show obstructive pattern
what does a CXR show?
as lungs are hyperinflated:
a) flattened diaphragm
b) hyperlucent lungs
c) increased antero-posterior diameter of chest
complications may be seen: pneumonia, pneumothorax
what does pulse oximetry and ABG show?
done in acutely unwell - assess for hypoxia and hypercapnia
screen for those that need home oxygen therapy
is sputum or blood eosinophilia suggestive of asthma or COPD?
how does asthma differ from COPD?
- onset is early
personal or family history, allergy, rhinitis, eczema, daily variability, responds to bronchodilators
what are the treatments of COPD?
monitor weight, nutrition status and physical activity
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
what is an acute exacerbation of COPD?
- 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
what is the management of acute exacerbation of COPD?
- 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