Asthma Flashcards
what is asthma
Asthma is a chronic respiratory disorder characterised by variable airway inflammation, airway obstruction, and airway hyper-responsiveness.
what is the pathophsyiology of asthma acutely/ allergic asthma
IgE-mediated type 1 hypersensitivity leading to mast cell degranulation and release of histamine
what are some key aspects of pathophysiology of chronic asthma in the airways
- type 2 immunity - involves Th2 T helper cells
- Bronchial hyper-responsiveness
- Bronchial inflammation
- Endobronchial obstruction
what is allergic asthma associated with
atopy eg. eczema or allergic rhinitis
which gender is asthma more common in
male
risk factors
- FH or PMH of asthma
- Exposure to allergens e.g. dust mites or pets
- history of atopic disease
-maternal stuff: smoking around kid, or in pregnancy or viral inf in preg ect, not being breastfed
what are the symptoms
- End-expiratory wheeze
- Dyspnoea
- Chest tightness
signs
- Symptoms may worsen after NSAID use
- Prolonged expiratory phase on auscultation
- Hyper-resonance to lung percussion
-Comes & goes in response to triggers
what are the factors based on which they decide the severity of an asthma attack
peak flow
speech
RR
Pulse
features of moderate asthma attack
normal speech
peak flow 50-75%
RR< 25
Pulse <110
features of severe attack
peak flow 33-50%
Cant complete sentences
RR> 25
Pulse> 110
extra features considered in life threatening + near fatal asthma attacks
CO2 levels, confusion, bradycardia, oxygen <92
overall features of life threatening asthma attack
- Peak flow <33%
- Oxygen <92%
- Normal CO2
- Confusion
- Bradycardia
What is the distinguishing feature of NEAR FATAL asthma?
RAISED CO2
What are the most common investigations you do and some extra to consider
spirometry
Fractional Exhaled Nitric Oxide
to consider: CXR (MOTSLY IN OLDER and smokers)
what values does spirometry provide
FEV1: forced expiratory volume - volume that has been exhaled at the end of the first second of forced expiration
FVC: forced vital capacity - volume that has been exhaled after a maximal expiration following a full inspiration
typical spirometry asthma findings
FEV1 - significantly reduced
FVC - normal
FEV1% (FEV1/FVC) < 70%
why is NO present in asthmatic inflammation
increased production of it from inflamed activated epithelial cells
diagnosis in >=17 yrs
1)patients should be asked if their symptoms are better on days away from work/during holidays.
- If so, referred to a specialist as possible occupational asthma
2) all patients should have spirometry with a bronchodilator REVERSIBILITY (BDR) test
3) all patients should have a FeNO test
diagnosis in 5-16
FeNO first and if >35ppb diagnose
if inconclusive or unavailable do spirometry with BDR (bronchodilator reversibility)
diagnosis in under 5s
diagnosis should be made on clinical judgement
what is a FeNO positive test
- in adults level of >= 50 parts per billion (ppb) is considered positive
-in children a level of >= 35 parts per billion (ppb) is considered positive
What is meant by bronchodilator reversibility?
Improvement in FEV1 of 12% or more after inhalation of SABA (salbutamol)
Reversibility testing results in children and adults
in adults, a positive test is indicated by an improvement in FEV1 of 12% or more and increase in volume of 200 ml or more
in children, a positive test is indicated by an improvement in FEV1 of 12% or more
How is an acute asthma attack investigated and what will it show?
ABG showing type 2 respiratory failure (hypoxia and hypercapnia)
1) SABA (Salbutamol)
2) SABA + low dose ICS (Beclomethasone or Budesonide)
- When do we add ICS? (3)
- Symptoms 3 or more times a week
- Night time waking
- Can be either at diagnosis or review
3) SABA + ICS + LABA (Salmeterol)
4) SABA + ICS (increase dose to max) + LABA + LTRA (Montelukast) or SR theophylline or Beta 2 agonist tablet
5) Use daily steroid tablet + high dose ICS + refer for specialist care
Describe the salbutamol inhaler (3)
- Blue inhaler (reliever)
- Tremor side effect
- Taken when needed
Describe the beclomethasone inhaler (3)
- Brown inhaler (maintainer)
- Oral candidiasis side effect
- Taken morning and night regardless of symptoms
What do we do if we need to step-down treatment in well-controlled asthma?
Reduce 25-50% of ICS
How do you manage an acute asthma attack? (5)
- Oxygen (target sats 94-98%)
- Salbutamol nebulisers
- Ipratropium Bromide nebulisers
- Oral prednisolone- (if unable to swallow: IV hydrocortisone)
- IV magnesium sulfate
( BE CAREFUL - INAPPROPRIATE FOR COPD exacerbation)
How might we treat patients not responding to full medical treatment an who have low O2, high CO2 and resp acidosis
Intubation and ventilation
What do we do if normal PaCO2?
Escalate to intensive care team because it’s a sign of exhaustion and is life threatening
Complications?
- Growth retardation
- Chest wall deformity
- Recurrent infections
- Pneumothorax
- Respiratory failure
- Exacerbations
PROGNOSIS
Many children improve as they get older- Adult onset asthma is usually chronic
