Obstructive & Restrictive Lung disease Flashcards
how are obstructive respiratory diseases categorised and why is this method effective
- the pattern of spirometry
- this is useful as it is quantitative, objective and is an accurate measurement of the lung function
- it is also repeatable and can be used to monitor the course of the disease
what are the two main measurements in spirometry
FEV1.0 and FVC
Poiseuilles Law
especially states that if the radius narrows then the resistance to air flow increases and the work load of breathing increases and therefore the lungs have to work harder causing shortness of breath
what is the physiology of asthma
essentially what happens in asthma is that, there is inflammation and swelling and fibrosis and increases in mucus secretion.
what is the physiology of COPD
essentially what happens in COPD is that, there is inflammation and swelling and fibrosis and increases in mucus secretion. There is also destruction of the elastic fibres that hold open the airway, this can lead to narrowing and potentially collapse
at what level in spirometry is an abnormality identified
- FEV1 <80% of predicted normal
- FVC<80% of predicted normal
- the FEV1//FVC ratio is < 0.7
spirometry findings in an obstructive disorder
- FEV1 is reduced
- FVC is usually reduced but to a lesser extent than FEV1
- the ratio is reduced <0.7
spirometry in restrictive disorder
- FEV1 reduced
- FVC reduced
- ratio is normal >0.7
what is FVC
forced vital capacity
F = this means the patient exhales as hard and as long as possible V = total volume in the lungs minus the residual volume C = sum of more than one volume
what is the fev1//FVC ration a measure of
the airflow obstruction, which is why in restrictive lung disease it is normal
what happens to the lungs in a restrictive lung disease
the lungs become stiff and fibrosed so all measurements tend to be reduced, as the lungs are less expansive
what happens to lungs in obstructive lung disease
this causes the trapping of air.
The working proportion of the lungs shifts upwards, the air is trapped in the alveoli and they are not ventilated but they are still perfused. this increased ventilation perfusion mismatching leads to the patient becoming hypoxic
ventilation rate (V)
refers to the volume of gas inhaled and exhaled from the lungs in a given time period
multiplying the tidal volume (volume of air inhaled and exhaled in a single breath) by the respiratory rate. In an average man, the ventilation rate is roughly 6L/min.
perfusion
refers to the total volume of blood reaching the pulmonary capillaries in a given time period.
what leads to this mismatching and how is it made worse
ventilation increases from the top to the bottom of the lungs (this means there is more at the bottom) this is the same with perfusion.
There is a mismatch however which causes:
top of the lung = under-perfused and preferentially ventilated
bottom of the lung = preferentially perfused and under-ventilated
this mismatch is made worse by obstructive and restrictive lung diseases
what are the most common obstructive lung diseases
asthma and COPD
also bronchiectasis and cystic fibrosis
what is important about the eosinophil and neutrophil count in asthma and COPD
in regards to eosinophils and neutrophils. If there is a high level of eosinophils and normal neutrophils then it is likely to just be asthma, however if there is normal eosinophils and high neutrophils then it is likely to be COPD. If both are high, COPD is not usually treated with steroids but if there is a high eosinophil count then this suggests an element of asthma which you should then treat with steroids
what are symptoms od asthma
cheese
breathlessness
chest tightness
cough
however could be asymptomatic between attacks
look for diurnal variation in symptoms and history of atopy (PEFR is useful)
OR symptoms could be in response to allergies or exercise or cold air
what is the pathophysiology of asthma
- airway narrowing/obstruction which can be reversible
- airway hyper-responsiveness
- airway inflammation (look for eosinophils)
what are the important mediators in asthma
leukotriene B4 and cysteinyl-leukotrines C4 and D4
interleukins IL-4, IL-5, IL-13
tissue damaging eosinophil proteins
(drugs tend to target these mediators)
genetic predisposition and potential triggers
symptoms can become worse in the presence of:
- viral
- allergens (e.g animal dander, dust mites, pollens and fungi)
- cold
- foods/nutrition (vitamin D, A, E levels?
- chemicals (smoke)
- exercise
non-pharmacological treatment
- achieve and maintain a normal BMI if overweight
- breathing exercise programmes
- stop smoking (patient and household members)
what is the criteria for COPD
symptoms have to be for more than 3 month in two consecutive years
predominant sign of a wheeze (spirometry assessment)
it effects both the airways and the lungs
how is COPD characterised
persistent airflow limitation that is usually progressive and associated with an enhanced chronic inflammatory response in the airways and the lungs to noxious particles or gases
epidemiology of COPD
- smoking
- indoor/outdoor pollution from biomass fuels
- genetic abnormalities (alpha 1 antitrypsin def. if early onset COPD)
- abnormal lung development
- age and sex (females at increased risk)
cannabis diagnosis
large bullae on xray
beware of a contaminated joint (aspergillosis)
alpha 1 antitrypsin def.
early onset COPD it is an enzyme produced in the liver that counteracts the proteinases (the enzyme that breaks down the lung tissue) autosomal codominance emphysema most marked in the lower lobe gene therapy research phase
pathophysiology of COPD
- inflammation and fibrosis of the bronchial wall
- hypertrophy of the submucosal glands and hyper secretion of mucous
- loss of elastic, parenchymal lung fibres (emphysema)
clinical presentation of COPD
Usually 50s and 60s
chronic cough (typically worse in the morning)
sputum production
increasing (over time) shortness of breath
diminishing exercise tolerance (specifics)
history of exposure to risk factors
pink puffer
increasing SOB but little cough pursed lips as alveoli tend to collapse barrel chest due to air trapping use of accessory muscles decreased breath sounds
blue bloater
blue = cyanosed
bloater = signs of right heart failure
expectorant cough
crackles and wheezes
could be weight loss skeletal dysfunction CVS disease depression osteoporosis
what are the five fundamentals of COPD care
- support the stopping of smoking
- pneumococcal and flu vaccine
- pulmonary rehab
- co-develop a personalised self-management plan
- optimise co morbidities
Domiciliary oxygen therapy
patients with a Pao2 < 7.3 - 8 kPa
must have stopped smoking
must be breathed for >15 hours/day to improve mortality
NON INVASIVE POSITIVE PRESSURE VENTILATION
Examples of restrictive lung diseases
- idiopathic pulmonary fibrosis
- hypersensitivity
- sarcoidosis
- connective tissue disease related to lung disease
dyspnoea, dry cough and malaise
bilateral fine crackles ad finger clubbing
characterises of restrictive lung diseases
overall lungs are smaller
decreased VC and decreased fev1.0 but ratio maintained
6 minute walk test
often palliative pathway
