Respiratory p1 Flashcards
What does spirometry measure?
Volume and speed flow of air during exhalation and inhalation
What is FEV1?
Forced expiratory volume: volume that has been exhaled at the end of the first second of forced expiration
What is FVC?
Volume that has been exhaled after a maximal expiration following a full inspiration
What is Kco?
Diffusion capacity of the lung per unit area for CO
What is TLco?
Diffusion capacity of the total lung capacity for CO
What is an obstructive patten on spirometry?
Normal (or increased FVC), reduced FEV1:FVC
What is a restrictive pattern on spirometry?
Reduced FVC, normal (or increased) FEV1:FVC
What does decreased TLco/Kco indicate?
issue with gas change, which can be due to either alveolar disease or vascular disease
Rules out chest wall / diaphragm pathology
What is asthma?
Chronic inflammatory condition of the airways, characterised by airway hypersensitivity
What are the symptoms of asthma?
wheezing and SOB Worse @ night or with exercise Diurnal variation Peak flow worst in morning chest tightness Bilateral widespread “polyphonic” wheeze
What will you find on examination for asthma?
Widespread expiratory wheeze
Pulmonary function = Decreased FEV1 relieved by B2 agonist
What are the common precipitants of asthma?
Environmental: pets, grass pollen, dust mites Viral infections Cold air Emotion Drugs: NSAIDS, aspirin, B-blockers Atmospheric pollution Occupational pollutants
What are the important history points for asthma?
Known precipitants, diurnal variation in symptoms, acid reflux
atopy hx, occupation and days off work/school
Exacerbations and whether they needed hospitalisation/ITU
How is asthma diagnosed?
CLINICAL: can do structured clinical assessment to see if:
episodes are recurrent, symptoms are variable, PH/FH or atopy
Recorded observation of wheeze
Variable PEF/FEV1
Absence of symptoms - look for alternate diagnosis
High probability: initiate treatment and if symptoms improve, diagnosis confirmed
Can do spirometry or FeNO if spirometry is normal
What will be the findings of asthma from spirometry?
FEV1 / FVC will be less than 70%
bronchodilators will reverse this
What is extrinsic asthma caused by?
Type 1 hypersensitivity reaction
Who does extrinsic asthma occur in?
Atopic individuals who show positive skin prick tests to common allergens, implying a definite extrinsic cause
What is intrinsic asthma caused by?
Non-immune mechanisms
Who does intrinsic asthma occur in?
Middle aged individuals, with no causative agent
What is late onset asthma more likely to be?
intrinsic
Describe the disease process of ACUTE asthma
- SM contraction narrows airway: bronchospasm due to production of histamine, prostaglandin D2 and leukotrienes (SM contraction NARROWS airway)
- Narrowing of airway due to chemotaxins (late phase)
- Airway hyperactivity
Describe the disease process of chronic asthma
Bronchoconstriction due to increased responsiveness of SM
Hypersecretion of mucus plugging the airway
Mucosal oedema = narrow airways
Can lead to pulmonary HTN in long standing disease
What might be observed in the sputum sample of a patient with chronic asthma?
Charcot-Leyden crystal (from eosinophil granules)
Curschman spirals (mucus plugs from small airways)
What are the features of acute severe asthma?
RR >25 HR >110 PEF 33-50% of best Can't complete sentences in one breath Accessory mm of respiration