Physiology and Obstruction

Question 1

what is an obstructive disorder

Answer 1

narrowing of airway - increased resistance
reduced inflow of gas
reduced inflation of alveolus

Question 2

obstructive lung diseases

Answer 2

asthma
copd
causing obstructive picture - bronchiectasis, cystic fibrosis

Question 3

factors affecting airway internal diameter

Answer 3

increased mucus production
anatomical features
autonomic and non-adrenergic/non-cholinergic (NANC) systems
inflammation

Question 4

features of larger airways

Answer 4

contain cartilage
relatively rigid

Question 5

features of small airways

Answer 5

no cartilage
susceptible to collapse

Question 6

what does bronchoconstriction happen quickly in response to

Answer 6

agonists

Question 7

what receptors are responsible for bronchoconstriction

Answer 7

muscarinic receptors

Question 8

what receptors are responsible for bronchodilation

Answer 8

beta 2 adrenergic receptors

Question 9

what neurotransmitter goes from the vagus nerve to muscarinic receptors for bronchoconstriction

Answer 9

acetyl choline

Question 10

what is asthma characterised by

Answer 10

reversible airways obstruction and an early and late phase response to stimuli

Question 11

features of asthma

Answer 11

multiple reasons for airway narrowing
smooth muscle thickening
bronchoconstriction
BM thickening
mucous plugging

Question 12

features of copd

Answer 12

increased mucous production
destruction of alveoli and connective tissue leading to collapse of conducting airways

Question 13

how is obstruction measured

Answer 13

peak flow
spirometry
lung volumes and flow

Question 14

factors determining airway resistance and flow

Answer 14

airflow
upstream pressure
downstream pressure

Question 15

what does airflow equal

Answer 15

airflow = (upstream pressure - downstream pressure) / resistance

airflow = volume of gas per unit of time

Question 16

what does a small decrease in radius lead to

Answer 16

big increase in resistance
therefore decrease in flow

Question 17

peak flow

Answer 17

peak expiratory flow fate
measures maximum speed of expiration
crude measurement of conducting airway flow
can aid in asthma diagnosis/management
excellent bedside and patient based tool

Question 18

FEV1

Answer 18

how much a patient can exhale in one second

Question 19

FVC

Answer 19

how much can a patient exhale altogether

Question 20

spirometry

Answer 20

forced expired volume in one second (FEV1)
forced vital capacity (FVC)
compared to predicted values based on age, sex and height
predicted values based on population of healthy individuals

Question 21

global lung initiative (GLI) lung function predicition

Answer 21

set up in 2008 to standardise predicted valued for spirometry
now adopted as gold standard
online tool for data interpretation

Question 22

ratio of FEV1 to FVC

Answer 22

useful to differentiate between obstruction and restriction
if less than 0.7 the suggest obstructive airways pathology
mild obstruction - biggest impact on FEV1
severe obstruction - also lose FVC

Question 23

reversibility of spirometry

Answer 23

used as diagnostic test for asthma - e.g. following bronchodilator
asthma reversible vs copd fixed obstruction
can also use bronchial challenge agents (histamine) to induce bronchospasm and obstructive spirometry