respiratory pathology Flashcards
what is a spirogram
A tracing of the relationship between maximal expiratory airflow and time
what are the 5 components of a spirogram
- forced vital capacity
- residual volume
- total lung capacity
- inspiratory capacity
- functional residual capacity
what are 2 ways to test for lung volume
helium dilution (difference in helium conc during inhale and exhale)
body plethysmography (measures pressure change in sealed booth)
whats the difference between obstructive and restrictive disorders
obstructive = airway obstruction
restriction = functional reduction in lung volume
how can u identify obstructive or restrictive disorders
through spirometry and peak flow
what is FEV1
forced expiratory volume in 1 second
(total volume of gas exhaled int he first second of a maximally forced exhalation after maximal inhalation)
what can a spirometer measure
FEV1 and FVC (forced vital capacity)
how can you measure both FEV1 and FVC
using vane anaemometer
what does a vitalograph show
plots volume expired against time (shows plateau)
what does a flow-volume curve show
plot volume expired against flow (derived from vitalograph)
check iPad notes for graph images
what does PEFR stand for and what does it mean
peak expiratory flow rate
- the maximal expiratory flow rate
what would show on graph due to obstructive spirometry
FEV1 is lower (flatter gradient)
- but same FVC reached as lung volume is unchanged
- FEV1:FVC ration is lower
what is radial traction
the elastic fibres of the surrounding alveoli pull on the walls of small airways and hold them open
what can show on graph due to restrictive spirometry
FEV1 middle reduced
- FVC is reduced to
- because both are lowered, FEV1:FVC ration stays similar
is pulmonary fibrosis obstructive or restrictive
restrictive
is COPD obstructive or restirictive
obstructive (airways collapse and get blocked by mucous walls)
what 2 components are part of the work of breathing and what are they
- compliance (expandability of lungs and chest wall)
- resistance (ease which gas flows through conducting airways)
decreasing compliance or increasing resistance leads to what?
decrease compliance = restrictive
increasing resistance = obstructive
define complience / equation
change in unit volume per unit pressure
compliance = volume/pressure
what feature of lungs help passive exhalation
elastic recoil of lungs which is one of the forces that help us passively exhale
what are 2 main properties of lung that affect its compliance
- elastic fibres in lung parenchyma (tissue)
- water tension in alveoli
explain how the water molecules inside alveoli can cause collapsing
- h20 molecules in alveolus have cohesive force
- the leads to inward pressure
- if left unchecked can lead to the collapse of the alveoli, decreased compliance and etc
how is prevention of alveoli collapse due to water cohesion taken care of
type 2 pneumocystis in alveoli release surfactants reducing this force
the lung has elastic recoil pulling inwards and chest wall has natural pull outwards
what is normal intrapleural pressure
negative throughout normal respiratory cycle (755mmHg)
inside = 760mmHg
outside = 760mmHg
what happens if theres hole in pleural
pressure equalises and lung collapses (pneumothorax)
what is poiseuilles law
flow is proportional to radius^4
what causes breath sounds
turbulent airflow going through airway
give some examples of meds used to open airway
beta 2 agonist (blue inhaler)
corticosteroids (brown inhaler)
leukotriene receptor antagonist
etc
what does IRV/ERV stand for
inspiratory/expiratory reserve volume
