Chronic asthma Flashcards
Asthma
Episodic, reversible airway obstruction due to
bronchial hyper-reactivity to a variety of stimuli
Pathophysiology
Pathophysiology
Acute:
1. Mast cell-Ag interaction causing histamine release
2. Bronchoconstriction, mucus plugs, mucosal swelling
Chronic (12h)
- TH2 cells release IL-3,4,5 causing mast cell, eosinophil and
B cell recruitment
- Airway remodelling
Precipitating factors
Stress + emotion Cold air Exercise Pollution Smoking Pollen Dust mites Animals Fungus
Atopy
Type 1 hypersensitivity reaction to variety of antigens
- asthma
- eczema
- hayfever
Symptoms
Cough - worse in morning and night Dry cough Wake up coughing Wheeze Dyspnoea
Signs
Tachypnoea, tachycardia
Widespread polyphonic wheeze
Investigations for asthma
Respiratory exam Basic obs Bloods - FBC, eosinophils, IgE, Peak flow Spirometry CXR
Spirometry pattern
Obstructive:
- scalloping
FEV1/FVC < 0.7
Improves with bronchodilator
General mx (TAME)
Technique for inhaler use Avoidance: allergens Monitor: Peak flow diary (2-4x/d) Educate: - Liaise with specialist nurse - Compliance - Emergency action plan
Stepwise drug treatment
1 SABA PRN + low dose ICS
- Low dose ICS+ LABA (Fostair) + SABA
OR
- low dose ICS + LTRA + SABA prn
- Medium dose ICS/LABA + SABA
- High dose ICS/LABA + SABA
- Add on tiotropium
- Oral steroids: prednisolone
When to step up medication
If use >1/d or nocturnal symptoms
LTRA
Montelukast - mast cell stabiliser
SABA
LABA
SAMA
LAMA
SABA - salbutamol
LABA - salmeterol
SAMA - ipratropium bromide
LAMA - tiotropium
Adenosine receptor antagonist
Theophylline
Acute severe asthma
1 of:
- PEFR - 33 - 50 %
- RR >25
- HR >110
- Can’t complete sentence in one breath
- SpO2 > 92%
- Use of accessory muscles
Life threatening asthma
1 of:
- PEFR <33%
- SpO2 <92%, PaO2 <8kPa
- Cyanosis
- Hypotension
- Exhaustion, confusion
- Silent chest
Admission criteria
Life-threatening attack
Feature of severe attack persisting despite initial tx
May discharge:
- if PEFR > 75% 1h after initial Rx
- stable on discharge meds for 24h
Discharge plan
TAME pt.
PO steroids for 5d
GP appointment w/i 2 wk
Resp clinic appointment w/i 1mo
Mx of severe asthma attack
- Sit up
- Oxygen 15L via non rebreathe mast - 94- 98%
- Salbutamol neb 5mg
- SAMA - ipratropium - - do not repeat within 4 hours
- Prednisolone PO - 40 - 50mg or Hydrocortisone IV if NBM -100mg
Life threatening:
- ITU - if ventilation needed
- Magnesium sulphate
- Consider aminophylline
Moderate asthma
Normal speech No features of acute severe or life threatening asthma PEFR 50 - 75% RR < 25 HR < 110
Asthma follow up after discharge
Within 2 days Continue prednisolone until recovery Review symptoms and check PEFR Check inhaler technique Modify treatment plan
Asthma control
No daytime symptoms No night awakening No need for rescue meds No exacerbations No limitation on activity Normal lung function
When to do FeNO test
FeNO test for all new adult diagnoses of asthma, and for use in young patients where there is diagnostic uncertainty or negative spirometry/bronchodilator reversibility.
When is a CXR done
If life threatening asthma
Suspected pneumothorax
Failure to respond to treatment
Criteria for discharge
Stable on discharge medication for 12 - 24 hrs
Inhaler technique has been checked
PEFR > 75% of best or predicted
Risk factors
FHx Atopy Low birth weight Maternal smoking Pollution
Advice when taking ICS
Salty gargle after as can cause oral candidiasis
Taken everyday regardless of symptoms
