influence of disease on respiratory function Flashcards
what is the importance of radius?
radius is the most important determinant of flow in a tube
How can you tell if there are obstructive or restrictive defects present?
use the FEV1/FVC ratio
- if ratio is < 70% = obstructive
- ratio > 80% - restrictive
what is dynamic compression of airways in normal and unhealthy people?
normal people: the flow rate is limited during forced expiration bcas of airway closure
abnormal: flow rate is limited in normal breathing
which respiratory disease is characterised by variable air flow obstruction that is totally or partially reversible with therapy or spontaneously?
Asthma
which drug can treat asthma?
Salbutamol
COPD is characterised by ….?
airflow limitation that is not fully reversible …. but related to noxious agents like smoke so if often preventable
What is dynamic hyperinflation ?
air is progressively trapped in lungs due to airway closure….. :. lungs are hyper inflated
- happens in emphysema
- causes an increase in: FRC, TLC, RV
is oxygen therapy a good treatment for dyspnea?
No. Oxygen therapy is used for hypoxia not dyspnea
what is dyspnea?
breathlessness- usually due to hyper inflated lungs (dynamic hyperinflation) as opposed to hypoxia
what happens to compliance in emphysema?
compliance increases because lungs become more stretchy
loss of alveoli —–> decreased radius —-> less recoil ——> increased compliance
what happens to compliance in Lung Fibrosis (Pulmonary Fibrosis) ?
decreased compliance
- deposits of increased collagen —-> stiffer lungs —-> decreased compliance
what does the Expiratory Flow Volume curve look like in Obstructive defects?
LOW flow rate compared to lung volume
what is the relationship between flow rate and lung volume in Restrictive defects ?
normal/ high flow rate compared to lung volume
