Asthma Flashcards
what is asthma
diffuse airway inflammation due to a variety of stimuli resulting in reversible partial or complete bronchoconstriction
summarise the pathophysiology of airway inflammation
bronchoconstriction
airway inflammation and oedema
hyper-reactivity due to narrowing of airways
airway remodelling (desquamation, angiogenesis etc)
what causes asthma?
exercise allergies pollen dust smoke
what are the symptoms of asthma
dyspnea, chest tightness, audible wheeze and cough
what are the signs of asthma
wheeze, tachypnea, tachycardia, pulsus paradoxus, hyper-inflation of chest, hyper-resonant percussion note, visible effort to breath, expiration phase prolonged
what are the signs of a severe asthma attack
resp rate >25
pulse >110
inability to complete sentences
PEF 30-50% of normal
what are the signs of a life threatening asthma attack
cyanosis exhaustion altered conscious level silent chest arrythmias type 1 resp failure O2 <92 PEF <33%
what questions do you ask in annual reviews for asthma
have you had trouble sleeping due to your symptoms
do you have your usual asthma symptoms in the day
has it interfered with your daily activities
what are normal breath sounds called
vesicular, longer inspiration than exp
what are bronchial breath sounds and when are they heard
abnormality in lung that is far from airways
heard in consolidation, lobar collapse with patent bronchus and lung cavity
gap between both phases, equal
how can you check for further consolidation
tactile fremitus
say 99 = shouldn’t be loud
say e
whispering
what types of wheeze are commonly heard
expiratory
polyphonic - heard if bronchioles are spasming
monophonic - small wheezing starting at different times - heard if pathology in local area
when are crackles or crepitations heard
on inspiration, in pneumonia, COPD, pulmonary fibrosis or oedema, lung abscesses
what are the two types of crackles
coarse v fine
what is a pleural friction rub and when is it heard
sounds like walking on snow, when two pleura rub against each other due to pleurisy
also in consolidation, pulmonary infarction
stridor
loud, high pitched crowing sound during inspiration
caused by UPPER airway narrowing - don’t need a stethescope
what is FVC
amount of air person can exhale after maximally inhaling
what is FEV1
vol of air you can exhale in one second after maximally inhaling
what is a normal FVC/FEV1 ratio
70%
what is the ratio in obstructive lung disease
<70%
COPD
what is the ratio in restrictive lung disease and give an example
> 70%, but FVC alone is decreased
pulmonary fibrosis
why do you get inspiratory crackles, and with which conditions would you hear coarse v fine crackles?
bc if peripheral airways have collapsed, then on inspiration the airways open and the alveoli are delayed on opening and hence you hear crackles
coarse - COPD
fine - pulmonary fibrosis
what is diffusing capacity for CO
partial pressure difference between inspired and expired O2, and hence extent of absorption into blood
asthma = normal or increased COPD = decreased due to decreased effective alveoli surface area
what are the normal values for ABGs
o2: 10-13 (if they are on oxygen, <11 is cause for concern)
co2: 4.5-6
pH: 7.35-7.45
HCO3: 22-26
base excess: -2 to +2
FIND TABLE FOR ACIDOSIS AND ALKALOSIS
type 1 resp failure?
pao2 is low and normal paco2
type 2 resp failure?
low oxygen and high CO2
what is the normal arterial-alveolar gradient and what does an abnormality signify
normal = 10
problem with lung
what is intermittent asthma
main 4 symptoms less than 2x a week less than 2x a month night time symptoms no problems between flare-ups PEF is 80% of normal less than 20% variability
what is mild asthma
main symtpoms 3-6x a week
2-4 a month night symptoms
PEFR 60-80% of normal
20-30% PEF variability between days
ALSO = controlled with low-dose controller or reliever inhalers
what is moderate asthma
symptoms daily
night time symptoms 5x a month
PEFR 60-80% of normal
controlled with ICS or LABA
what is severe asthma
symptoms daily
frequent night time symptoms
PEFR less than 60% of normal
requires ICS or LABA to prevent it becoming uncontrolled, or if it is uncontrolled despite treatment
what are the 4 steps to managing asthma
- mild - give them a SABA (salbutamol, 100-200mcg when required)
2 mild persistant - give them a SABA, add inhaled corticosteroid: fluticasone or beclometasone dose depending on severity
3 moderate persistant - LABA, SABA, and increase steroid dose if needed, if not working = add leukotriene receptor antagonist (montelukast), or theophylline and inhaled LAMA like ipratroprium
4 - severe - inhaled steroid at highest dose and if not working then lowest dose oral prednisolone
how do you manage an acute exacerbation of asthma once in hospital
- supplemental o2 to maintain it above 92%
- salb 5mg or terbutaline 10mg nebulished with oxygen (6-8L)
- add ipratropium 0.5mg.6 hours if life-threatening - can combine with salb
- IV hydrocortisone 100mg or pred 40-50mg orally
- if not responding = Mg IV 1.2-2g
what do you do while waiting for an ambulance
six puffs of salb at once or 1 puff every 5 minutes and reassess every 15
if PEFR <75%, repeat salb every 15-30min and add ipratropium
if not responding initially, add Mg
if improving = continue salb and ipratropium, if PEFR >75% give pred 40mg OD for 5-7 days
if not = ICU, mechanical ventilation
when and how can you discharge an asthmatic patient after a serious attack
24 hours off nebuliser
PEFR >75% with <20% variation
give normal inhalers, and pred as above
follow up after 48 hours
what is salbutamol and what are the side effects
short-acting b2 adrenoreceptor agonist causes bronchodilation
binds to b2 receptors = fine tremor and bradycardia
why is propanolol contraindicated in asthmatic patients?
beta-blockers = causes bronchoconstriction
example of a LABA and how long does it last
salmeterol
12 hours
what is terbutaline
SABA
what are beclomethasone and fluticasone
GCC - anti-inflammatory and immunomodulating
flucitasone combined with salmeterol = seretide
what is montelukast?
leukotriene receptor antagonist - inhibits migration of eosinophils, neutrophils, airway oedema and bronchoconstriction
theophylline? SE
inhibits phophodiesterase and prostaglandin production, causing bronchoconstriction, vasodilation
SE: adrenergic activation so tachycardia, palpitations, headaches, diarrhea etc
how does ipratropium work
anti-muscarinic (muscarinic antagonists) = inhibits Ach-mediated bronchoconstriction from vagal impulses (can lead to constipation, cough, diarrhoea, dry mouth)
what is sodium cromoglicate
mast cell stabiliser and prevents release of histamine, leukotrienes
how do you analyse chest x-rays
read case 2 notes
what is the FeNO test
fractional exhaled nitric oxide
abnormal >40
indicates inflamed airways
brand names of inhalers
- ICS: clenil, QVAR, Pulmicort, flixotide
- LABA: serevent
- LAMA: Spiriva
- Combination inhaler: Seretide, Symbicort, fostair
what investigations do you do for asthma?
- spirometry
- PEFR
- FeNO2
