COPD Flashcards
what is COPD?
limited airflow that isn’t fully reversible
both emphysema & chronic bronchitis (both progressive, co-exist)
PROGRESSIVE airflow limitation
abnormal inflammatory response of lungs to noxious particles / gases
what is the primary cause of COPD?
cigarette smoking
what are the causes of COPD?
tobacco smoke
air pollution
occupational exposure
a-1 antitrypsin deficiency (destroy alveolar walls)
what are the pathological changes of COPD?
- hypertrophy of mucus-secreting glands
- hyperplasia of goblet cells (psudostratified ciliated columnar)
- ciliary dysfunction
- breakdown of elastin (destruction of alveolar wall & structure)
- formation of larger air spaces & reduced total SA for gas exchange (bullae)
- vascular bed changes –> pulmonary hypertension
what is emphysema?
elastin breakdown & subsequent loss of alveolar integrity –> permanent destructive enlargement of airspaces DISTAL to terminal bronchioles
what is chronic bronchitis?
excessive mucus secretion & impaired removal of secretions (from ciliary dysfunction)
why does COPD lead to increased airway resistance?
- luminal obstruction of airways by mucus (slow moving, thick, ciliary dysfunction)
- narrowing small bronchioles - normally kept open by outward pull (radical traction) by elastin
- decreased elastic recoil –> reduced expiratory force –> air trap (increase residual volume)
what leads to hyperinflation?
expiratory flow limitation (decreased elastic recoil, narrowing small bronchioles, luminal obstruction)
what predisposes patient to hypoxia?
airway narrowing & destruction of lung parenchyma
especially during exercise
what is hypoxia from?
airways narrowing & pulmonary vasculature changes
what does progressive hypoxia causes?
pulmonary vasoconstriction & vascular SM thickening
with subsequent pulmonary hypertension + RH failure (cor pulmonale)
what is a typical history of COPD?
gradual onset
usually present in older people with long history of smoking
what are the symptoms of COPD?
- cough (usually initial)
- frequent morning cough (constant through progression)
- usually productive cough (sputum produced)
- SoD (dyspnoea) - usually on exertion, progress to at rest
physical examinations of COPD patients
- tachypnoea
- use of accessory muscles of respiration
- barrel chest
- hyper-resonance on percussion
- reduced intensity (distant) breath sounds
- reduced air entry (poor air movement)
- wheezing
what causes tachypnoea?
increase RR to compensate for hypoxia & hypoventilation
what are the accessory muscles of respiration?
SCM
scalene
pec minor
why use the accessory muscles of respiration?
difficulty moving air in & out of lungs
how can you tell if a patient is using accessory muscles of respiration?
tracheal tug
intercostal recession
subcostal recession
nasal flare
what is barrel chest?
increase A-P diameter of chest
why will patient present with barrel chest?
hyperinflation (decreased elastic recoil --> limited expiratory flow rate) air trapping (secondary to incomplete expiration)
why will there be hyper-resonance on percussion?
hyperinflation & air trapping
why will there be reduced intensity (distant) breath sounds?
caused by barrel chest, hyperinflation & air trapping
why will there be reduced air entry (poor air movement)?
secondary to loss of lung elasticity & lung tissue breakdown
what are late features of COPD?
- central cyanosis
- flapping tremors
- signs of RH failure
what causes central cyanosis?
hypoxia due to type 2 resp failure
what causes flapping tremors?
CO2 retention (hypercapnia)
what are signs of RH failure?
- distended neck veins (raised JVP)
- hepatomegaly (back up of portal venous system)
- ankle oedema
why will there be signs of RH failure in late feature of COPD?
secondary to pulmonary hypertension
what are investigations carried out for COPD?
lung function tests:
spirometry (vitalograph & flow- volume)
what will the spirometry show for a patient with COPD?
obstructive pattern (FEV1/FVC <70%)
what will spirometry show after bronchodilators?
why do this?
limited reversibility
rule out asthma
what will vitalograph (time-volume) show?
low FEV1, nearly normal FVC
what will flow volume loops show?
typical obstructive pattern (low PEFR & scalloping)
what is a feature of emphysema in terms of lung diffusion capacity?
decreased diffusing lung capacity for CO (DLCO)
how do you check for lung diffusion capacity?
patient breathes in mixture of CO & helium after max expire
hold breath for 10 seconds then measure volume & conc to work out diffusing capacity
(CO because pCO = 0, high affinity for Hb, small amount - toxic)
what would CXR of COPD look like?
hyper-inflated lungs
what does hyper-inflated lungs lead to (on CXR)?
flattened diaphragm
hyperlucent lungs
increased A-P diameter of chest
what else can CXR show aside from hyper-inflated lungs?
complications of COPD e.g. pneumonia & pneumothorax
what is CXR useful for?
to rule out other pathologies e.g. lung cancer in patient with chronic cough
what tests will be checked on patients aside from CXR & spirometry?
pulse oximetry & ABG analysis
when would you carry out pulse oximetry & ABG analysis?
acutely unwell patients
to assess hypoxia & hypercapnia
CBG - home ox therapy
