Restrictive And Obstructive Lung Disease Flashcards
Name and explain the 2 categories of lung disease
Obstructive: Reduction in flow through airways
Restrictive: Reduction in lung expansion
Both reduce ventilation
what is inspiratory reserve volume?
maximum amount of additional air that can be drawn into the lungs by determined effort after normal inspiration
what is tidal volume?
normal volume of air displaced between normal inhalation and exhalation, no extra effort applied
what is the expiratory reserve volume?
additional amount of air that can be expired from the lungs by determined effort after normal expiration
What is residual volume
the amount of air left in the lungs after fully exhaling
what is the functional residual capacity?
volume of air left in the lungs after normal expiration
what is the vital capacity?
maximum amount of air a person can expel from their lungs after a max inhalation, equal to the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume
what is the inspiratory capacity?
amount of air that can be inhaled after the end of a normal expiration
What is compliance
-(measure of elasticity) how easy it is for the lungs and thorax to expand during pressure changes
-ruled by changes in volume and pressure
Equation for compliance
C = dV/dP
Where dV is the change in volume and dP the change in pleural pressure
what is the inter-pleural pressure?
-(intrathoracic pressure) pressure within pleural cavity
-usually less than atm pressure, so negative
when is compliance highest?
at moderate lung volumes
when is compliance lowest?
at lung volumes at either extremities (v. High or v. Low)
what is lung hysteresis?
(Hysteresis - physical changes lag behind changes in the effect causing them)
the compliance being different on inspiration and expiration for identical volumes
what is low compliance caused by?
lungs being stiff so more work is required to inspire e.g. in pulmonary fibrosis, lung tissue loses distensibility and becomes more rigid
what is high compliance caused by?
loss of elastic recoil so difficult to exhale air - extra work required to get air out of the lungs. Often problems with inhalation too as high compliant lung = collapsed alveoli which makes inflation difficult.
eg. Emphysema, elastic tissue is damaged in response to inhaled irritants, such as cigarette smoke.
what is the relationship between lung function and age?
lung function decreases as you get older
what is the relationship between compliance and age?
Compliance increases with age
when does peak inspiratory rate and plateau pressure increase?
when elastic resistance increases or when pulmonary compliance decreases
what is the difference between fibrotic and emphysematous lungs regarding changes in lung volume w changes in pressure?
emphysematous lungs have larger changes in lung volume
RV - amount of air remaining after full exhalation
What are the 2 major components to the elastic recoil of the lungs
-anatomical component: elastic nature of cells and ecm, most of ecm is elastin
-elastic recoil due to surface tension generated at air-fluid interface, as air comes out, alveolus reduces in size and the surface tension involved helps w elastic recoil
what could narrowing of the airways be due to?
-excess secretions: more mucus, can be temporary
-brochoconstriction: asthmatics will suffer from this, airways narrow in response to irritants
-inflammation due to underlying infection
In all cases there is an increased resistance to the flow of air
what is FEV1?
volume of air that a patient can exhale in the first second of forced expiration
what is FVC?
total volume of air that the patient can forcible exhale in one breath
what is FEV1/FVC?
ratio of FEV1 to slow vital capacity
Values of FEV1 and FVC are expressed as a percentage of the predicted normal for a person of the same sex, age and height
what is used to measure lung volume values?
Spirometer
what is a flow volume loop?
a plot of inspiratory and expiratory flow (L/sec) against volume (L) during forced expiration
describe the appearance of a normal spirometry
rapid rise to max expiratory flow followed by a steady, uniform decline until all the air is exhaled
how will the spirometry be different for someone with an obstructive disease?
the FEV1 will be lower
how is an obstructive disease defined?
FVC is less than 80% of predicted FVC
how is the flow volume loop different for a person suffering from an obstructive disease?
-initial flow and peak flow c an be similar
-sharp fall in flow rate so concave curve
-longer to exhale so FEV1 will change but FVC may stay the same
what are the signs and symptoms of chronic bronchitis?
-daily productive cough for three months or more in at least 2 consecutive years
-overweight and cyanotic
-elevated Hb
-peripheral oedema (oedema in tissues perfused by peripheral vascular system)
-rhonchi and wheezing
-hypertrophy of submucosal glands so hypersecretion of mucus
-oedematous - bloater, probs due to right ventricular failure bc less blood is being pumped which causes fluid and water retention
-cough
what are the signs and symptoms of emphysema?
-permanent enlargements and destruction of airspaces distal to the terminal bronchiole
-older and thin
-severe dyspnea
-quiet chest
-x-ray will show hyperventilation with flattened diaphragms
-hypoxemia so pink
-barrel chest (loss of skeletal muscle and subcutaneous fat)
-alveoli can rupture
-respiratory muscle fatigue from increased use
-no cough
what are the two types of emphysema?
centriacinar/centrilobular and panacinar/panlobular
what is Centriacinar or centrilobular emphysema?
-central part of acinus affected with distal alveoli unaffected
-upper lobes, especially apical segments are involved
-closely involved w cigarette smoking
what is panacinar or panlobular emphysema?
-entire acinus is affected, from respiratory bronchiole to distal alveoli
-lower lobes affected
-closely associated with α1 antitrypsin deficiency
what are the differences between COPD and asthma?
-almost all COPD patients are smokers, fewer asthmatic smokers
-rare for COPD patients to show symptoms under 35, asthmatics do
-common for COPD patients to have chronic productive cough, uncommon for asthmatics
-COPD patients have persistent and progressive breathlessness but variable for asthmatics
-night time waking w breathlessness is uncommon for COPD patients but is common for asthma patients
-significant diurnal variability common for asthmatics but not for COPD patients
-asthma is reversible, COPD is not
name atopic and non-atopic triggers of asthma
-atopic (extrinsic): allergies, contact w inhaled allergens
-non-atopic (intrinsic): respiratory infections, cold air, stress, exercise, inhaled irritants, drugs
what are the differences in spirometry for a patient with a restrictive diseases?
-reduced vital capacity
-FEV1 can remain unchanged or increase
what are the differences on a flow volume loop for a patient with a restrictive disease?
-reduction in air removed
-reduction in peak flow
how does spirometry indicate the presence of an abnormality?
-FEV1 <80% predicted normal
-FVC <80% of predicted normal
-FEV1/FVC ratio <0.7
what will an obstructive disorder show on spirometry?
-FEV1 reduced
-FVC usually reduced but to lesser extent than FEV1
-FEV1/FVC ratio reduced
what will a restrictive disorder show on spirometry?
-FEV1 reduced
-FVC reduced
-FEV1/FVC ratio normal
how do asbestos affect your lungs?
-when breathed in, they can settle at the bottom of lungs and stay there for a lung time w/o causing problems and then 30/40 years later you will develop either fibrosis or mesothelioma or asbestosis
what is the underlying mechanism of IPF?
-scarring of lungs so build up of fibrotic tissue, leading to lower compliance
what does IPF involve?
-alveolar remodelling
-fibrous tissue build up
-scarred interstitium which disrupts exchange of oxygen and carbon dioxide bw alveolus and blood vessels
