Resp - Asthma Flashcards
Definition
Type 1 hypersensitivity reaction = Reversible paroxysmal constriction of the airways with inflammatory exudate and followed by airway remodelling
Most chronic condition of children
Epidemiology and risk factors
- Genetic
- Prematurity
- Low birth weight
- Parental smoking
- Viral bronchiolitis in early life
- Cold air
- Allergen exposure e.g. dust
- Bottle fed
Signs
- Diurnal peak expiratory flow rate (PEFR) variation
- Dyspnoea and wheeze
Symptoms
- Episodic shortness of breath
- Dry cough
- Wheeze and ‘chest tightness’
- Features of atopic disease e.g. eczema
Diagnosis < 5 years
Based on clinical judgement with regular reviews
- Perform tests once child reaches 5 years old
Diagnosis 5-16 years
FIRST LINE = Spirometry: FEV1/FVC < 70% (obstructive)
Bronchodilator reversibility = an improvement of FEV1 > 12%
Fractional exhaled nitric oxide: when spirometry is normal or obstructive spirometry with negative BDR test > 35 ppl
PEFR: multiple times a day over 2-4 weeks when BDR + FeNO inconclusive > 20% diurnal variation
Treatment < 5 years
- SABA
- (Not controlled on 1. OR newly diagnosed with Sx > 3 weeks OR night time waking)
SABA + trial paediatric moderate dose ICS for 8 weeks
- If Sx do not improve during trial consider alternative Dx
- If Sx resolve but recur within 4 weeks of stopping trial: restart paediatric low-dose ICS
- If symptoms resolved but recur beyond 4 weeks stopping trial: repeat 8 week trial of paediatric moderate dose ICS - SABA + paediatric low dose ICS + LTRA
- Stop LTRA and seek expert opinion
Paediatric dosing of ICS
Low dose < 200 micrograms budesonide
Moderate dose 200-400 micrograms budesonide
High dose > 400 micrograms budesonide
Treatment 5-16 years old
- SABA
- SABA + paediatric low dose ICS
- SABA + paediatric low dose ICS + LTRA
- SABA + paediatric low dose ICS + LABA + consider stopping LTRA
- SABA + switch ICS/LABA to MART
- SABA + moderate dose ICS + MART
OR SABA + moderate dose ICS + LABA - SABA + (one of the following)
- Increase ICS to paediatric high dose (fixed dose or MART)
- Trial additionally agent e.g. Theophylline
- Seek expert opinion
Complications
- Asthma exacerbation
- Pneumothorax
Asthma exacerbation
Airway bronchospasm and an inflammatory response leading to muscosal oedema and secretion
This results in obstruction of the bronchioles leading to increased work of breathing in order to maintain adequate oxygenation
Triggers
- Viral infection
- Inhaled allergen
- Exercise
- History of atopy : such as eczema or allergic rhinitis
- Medications : particularly NSAIDs and non-cardioselective beta-blockers
Moderate clinical features
SpO2 > 92%
No clinical features of severe asthma
Severe clinical features
Any one of:
- SpO 2 < 92%
- PEFR 33-50% predicted
- Can’t complete sentences in one breath
- Too breathless to talk or feed
- Heart rate > 140 (1-5 years)
- Heart rate > 125 (>5 years)
- Respiratory rate > 40 (1-5 years)
- Respiratory rate > 30 (>5 years)
Life threatening clinical features
Any one of the following in a child with severe asthma:
- SpO 2 < 92%
- PEFR < 33% predicted
- Silent chest
- Poor respiratory effort
- Agitation
- Exhaustion
- Cyanosis
- Hypotension
- Confusion
Diagnosis
FIRST LINE = PEFR <33% of predicted suggestive of a life-threatening attack
ABG: low pO2 and normal or high pCO2 is worrying as it suggests exhaustion
Bloods
CXR: shows consolidation if the exacerbation is triggered by infection, as well as a pneumothorax = complication of asthma exacerbations
Treatment for all severities
- Oxygen if SpO2 < 94%
- Inhaled salbutamol +/- ipatropium bromide
(SABA = FIRST LINE + ipatropium offered if needed) - Corticosteroids
= Prednisolone if child alert and can swallow otherwise ofdter IV hydrocortisone
= Course of 3 days usually sufficient
Treatment for life threatening exacerbation
FIRST LINE = IV bronchodilation = magnesium sulphate
SECOND LINE = IV salbutamol and aminophylline
Finally if all else fails ventilation or intubation
Complications
Pneumothorax
Respiratory failure
Medication to give on discharge
Oral prednisolone 30-40mg for 3-5 days and GP follow up for 48 hours
