case study - emphysema

what is obstructive lung disease? give examples.

airways are narrowed, which results in resistance to air flow during breathing

e.g. emphysema, chronic bronchitis, chronic asthma

what is restrictive lung disease? give an example.

the condition of fibrous lung tissue, which results in a decreased ability to expand the lungs

e.g. pulmonary fibrosis

explain the pathophysiology of emphysema

alveoli become damaged and enlarged, losing their elasticity and can't effectively contract and expand during breathing. this results in air trapping

lungs then become less effective at transferring o2 into the bloodstream and removing co2 from body due to hyperinflation from the trapped air and loss of elastic recoil

what are the risk factors for emphysema?

• smoking

• air pollution

• age (>40yrs)

what are the two types of emphysema?

- centri acinar
- pan acinar

what is centri acinar?

where only the proximal part of the acini is affected, the distal alveoli is spared

it is a typical pattern in smokers

what is pan acinar?

where the acini is uniformly enlarged

the distal alveoli is involved first

is typical in α1-antitrypsin deficiency

why do people with emphysema have an increased volume of mucous?

alveoli become damaged and lose their elasticity so they have trouble pushing out air effectively, leading to air being trapped in the lungs

because air traps can't fully empty, they create spaces where mucous can accumulate due to irritation and inflammation of mucous producing cells

trapped mucous can't be cleared out properly due to damaged airways

reduces efficiency of gas exchange

what is the ventilation-perfusion (V/Q) ratio?

compares amount of air reaching alveoli (ventilation) to amount of blood flow reaching the alveoli (perfusion)

how does emphysema affect the V/Q ratio?

V/Q ratio increases (damaged alveoli lose elasticity and become overinflated, therefore there is plenty of air but blood flow is less)

how does chronic bronchitis affect the V/Q ratio?

V/Q ratio decreases (increased mucous production blocks airways, leading to inadequate ventilation, however blood flow may still occurs in these areas)

what is cor-pulmonale?

right heart failure

abnormal enlargement of the right side of the heart as a result of disease of the lungs or the pulmonary blood vessels

how does chronic obstructive pulmonary disorder (COPD) lead to cor-pulmonale, thus, causing right side heart failure?

COPD (includes emphysema and chronic bronchitis) results in airflow obstruction due to narrowed airways.

this can lead to pulmonary hypertension due to high pressure in pulmonary arteries

if pulmonary hypertension is untreated, it can lead to cor-pulmonale where right side of heart is enlarged due to increased pulmonary pressure

over time, right side of heart has to work harder to push blood against elevated pressure

what would you measure on a spirometry for a patient with emphysema and why?

• decreased FEV1 - due to severe reduction in airflow

• decreased FEV1/FVC ratio - less than 70% is indicative of obstructive lung disease

• increased RV - due to air trapping

• increased TLC - due to hyperinflation

why does pink puffer occur (emphysema)?

damage to alveoli means blood can't be oxygenated, causing hyperventilation to get more o2 into lungs using accessory muscles -> pink complexion

why does blue bloater occur (chronic bronchitis)?

obstruction in bronchi reduces ventilation, low o2, high co2, leading to cyanosis -> blue

increased obstruction means increased residual volume (volume of o2 remaining in lungs after max exhalation) -> bloating