asthma Flashcards
How do you use a peak flow to diagnose asthma?
PF diary over 2 weeks
AT LEAST BD PF measurements- best of 3 (should be within 40ml of each other)
variability >20%
How do you identify airflow obstruction with spiro?
FEV1/FVC <70%
ratio changes so should use the lower limit of normal to prevent underdiagnosis in children and overdiagnosis in adults
>400ml improvement of FEV1 after 6-8weeks of ICS
How do you identify airflow obstruction with reversibility?
FEV1 imrpoves by >12% or 200ml
Can do Spiro off treatment 24hr off BD ics/laba or 36hrs off od ics/laba
What are the key differences between BTS/nice/GINA diagnosis of asthma?
BTS - emphasis on probability of asthma based on signs/symptoms
BTS -Test for airflow can influence prob of asthma
Nice - req evidence of positive objective tests
Gina- objective tests
BTS - option for additional ix (feno, IgE) gina- feno can be used to support
How do you test for airway hyper responsiveness?
Direct:
Increasing doses of histamine or methacholine
Drop of 20% in fev1. If less than 8mg/ml= pos false neg rate <10%
Indirect:
Mannitol
Fall in fev1 >15% or 10% fall between doses
correlates better with Eo airway inflam
What are T2 biomarkers?
Correlates with airway eosinophilic inflam
Feno and peripheral blood eosinophil count
What does a raised feno reflect?
Il4 and il13 induced induction of inhaled nitrous oxide
Surrogate marker for airway eosinophilia
Diagnosis for asthma specificity>sensitivity
What can cause a “falsely” raised feno?
Male, old age, atopy nitrate rich food (beetroot), rhinoviruses, hiv, chronic rhinitis
What can cause a “falsely” decreased feno?
Smoking, inhaled steroids, alcohol (before test), Spiro (should do feno FIRST), leukotrienes, prostaglandin E2, physical exercise (before test)
What are Charcot leyden crystals?
Seen on sputum micro which is made from eosinophilic granules
Seen in nasal polyposis
What treatment would you give a minimally symptomatic mild asthmatic?
Prn ics/laba
Mild asthma- high adverse risk. 30-37% acute asthma, 16% near fatal, 15-27% fatal
How can we monitor asthma control without investigating?
RCP 3 q, asthma control questionnaire, asthma control test
What is the mechanism of omalizumab? And what is the NICE indication?
Anti igE
IgE mediated asthma with >4courses of pred in a year
IgE <700
need to have year round allergies- not just seasonal ones
What is the mechanism of Mepolizumab? And what is the NICE indication? administration?
Anti il5
BEC >300 and 4 courses of pred/year or maintenance of 5mg for 6 months
BEC >400 and 3 courses of pred/year
SC
What is the mechanism of benralizumab? And what is the NICE indication? administration?
Anti il5 receptor alpha
BEC >400 and 3 courses of pred/year
BEC >300 and 4 courses of pred/year or maintenance of 5mg for 6 months
SC 4 weekly
