clinical application of lung mechanics Flashcards
what is COPD?
what happens to compliance and elstastance?
what happens to airway resistance and why?
what is COPD caused by?
chronic obstructive pulmonary disease - comination of chronic bronchitis and emphysema
compliance = high
elastance = low- loss of elasric fibre in alveoli
loss of radial traction = collapse of airway = diameter of airway less = resistance up
smoking, pollutants, genetics
what is chronic bronchitis?
what chnages occur?
what doe these chnages cause?
disease pf the small airways - when the small bronchi and bronchioles are chronically inflammed
hypersecretion of mucus, reduced cillia, epithelial remodelling, loss of small airways = higher resistance, less clara cells = less surfactant = more surface tension
high airflow resistance, surface tension increase, small airway collapse
what is emphysema?
what does elastase do?
what does this cause?
what is the difference betweeb small bronchus and bronchiole?
how does a bronchiole remain open in exhilation?
abnormal enlargement of airspaces (aleveoli)
elastase from inflammatory cells detroy alveolar cell walls and elastin
reduces elastic recoil (elastance) = hard to exhale
small airways collapse due to less radial tratcion
small bronchus has cartillage to help keep open and glands
radial traction
what is radial traction?
what diseases cause this to lessen?
what shape of chest is often seen in emphysema - explian why?
the outward tugging action of the alveoliar walls on bronchioles which prevents their collapse in expiration
COPD and emphysema
barrel chest
it is the anteroposterior to transerve ratio - usuallu is 1:2
but in emphysema it is 1:1 as the chest has increased air from insudfficent elasrtic recoil in expiration = digrphragm still flattened and chest more full of air
what is atelectasis?
why can this happen?
is compliance effected?
inadequate expansion or collapse of alveoli
not enough surfactant = alveoli collapse bc of the surface tension
compression atelectasis = pressure on alveoli e.g. pneumothorax, obesity, pleural effusuion, post GI op
resorption atelectasis = airway obstructed therefore down stream alveoli collaspse e.g. muscus in pneumonia or tumor
yes - compliance is lower as alveoli are harder to expand - alveoli not ventilated
what is interstitial lung disease?
what does it do to elatstance and compliance and why?
what else is affected?
what can cause it?
resting lung volume?
thickening of pulmonary interstitium
sometimes reversible if caught early
elastance up due to more elastin, collagen, fibroblasts = more recoil
compliance down as thickening = harder to stretch = inervsely proportional
gas exhange = alveolar capillary membrane effected = more diffusion distance
exposure (asbestos, drugs, mould) , autoimmune, idopathic
it is smaller as recoil gooooood
sx of interstitial lung disease?
signs
dru cough
dyspnoea
fatigue
finger clubbing
gradula progression
pleural effusions, clubbing, bi basal inspiratory lung crackles, decreased lung exerstion on paplation
in intersistial lung disease is functional residual capacity reduced or increased?
what is neonatal repiratory distress syndrome?
signs
what is the same between NRDS and intersitial lung disease?
reduced - expiration stronger
when a preterm baby is born and lungs no developed enough to produce sufficent surfactant = surface tension high = compliance low = laboured breathing
lung is stiff and some alveoli collapse
grunting, nasal flaring, intercostal and subcostal retractions, high rr, cyanosis
both have reduced compliance and increased elastance
what is pneumothorax?
what is hypoventilation?
whe the pleural seal is broken by a break in visceral and or parietal pleura resulting in air in ther plerual space = compresses lung
intrapleural soace is always negative pessure so air will always flow inwards
failure to breath rapidly or deep enough resulting in all alveoli being poorly ventlated
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