Resp Flashcards
Features of asthma
Characterised by reversible and paroxysmal constriction of airways with airway occlusion by inflammatory exudate and late airway remodelling
Epidemiology of asthma
Commonest chronic condition in children
- 1 in 11
Peaks between 5 and 15 years of age
Pathophysiology of asthma
Multi-factorial disease
Susceptible individuals have an exaggerated response to various stimuli
Type 1 hypersensitivity
- driven by Th2 type T-cells
- allergens presented by dendritic cells
- cytokines released -> activation of humoral immune system
- increased proliferation of mast cells, eosinophils and dendritic cells
- leukotriene C4 and histamine
Trigger factor leads to airway inflammation
- hypersecretion of mucus
- airway muscle constriction
- swelling bronchial membranes
Leads to narrow breathing passages
Risk factors for asthma
Genetic factors - asthma/atopy in parents or siblings Environmental factors - low birth weight - parental smoking Viral bronchiolitis in early life Atopic dermatitis
Precipitating factors for asthma
Cold air and exercise
- drying of airways leads to cell shrinkage which triggers an inflammatory response
Atmospheric pollution
Drugs
- NSAIDs - shunt the arachidonic acid pathways towards the production of leukotrienes which are toxic to the epithelium
- beta-blockers - prevent bronchodilatory effect of catecholamines on airways
Exposure to allergens
Disease severity of asthma
Infrequent episodic wheezing - discrete episodes lasting a few days with no interval symptoms Frequent episodic wheeze - 2-6 weekly Persistent wheezing - most days and disturbed nights
Features of preschool wheeze
Wheezing very common in preschool children
- up to 50% have significant episode of wheeze by their 5th birthday
Most commonly caused by human rhinovirus or respiratory syncytial virus
Most outgrow their wheeze
Episodic viral wheeze - wheezing only in response to viral infection and no interval symptoms
Multiple trigger wheeze
- wheeze in response to viral infection but also to other triggers such as exposure to aeroallergens and exercise
Clinical features of asthma on examination
Signs - Expiratory wheeze - non-productive cough - worse at night - Dyspnoea and chest tightness - Features of atopy Signs - chronic - Hyperinflation of chest Signs - acute - Respiratory distress - Reduced chest expansion - Widespread polyphonic wheeze across the chest
Investigations for asthma
Spirometry - normal in between exacerbations - obstructive pattern (FEV1:FVC < 70%) - bronchodilator reversibility Peak Expiratory Flow Rate (PEFR) Bronchial provocation tests Exercise testing Skin prick testing Exhaled nitric oxide (ENO) - NO produced in bronchial epithelial cells - production increased in those with Th2-driven eosinophilic inflammation Baseline CXR
Management of asthma
Aim to achieve good symptom control
Stepwise approach
- step 1 = as required short-acting beta-2 agonist (salbutamol)
- step 2 = regular preventer therapy with inhaled corticosteriods
- step 3 = initial add on therapy
- long-acting beta-2 agonist = salmeterol/formoterol
- increase ICS dose
- leukotriene receptor antagonist = montelukast
- step 4 = increase dose of ICS
- step 5 = regular oral steroids and referral to respiratory paediatrician
General management points for asthma
Aerosol inhaler devices should always be used with a spacer device
Question compliance
LABA should not be prescribed as monotherapy - only in combination with ICS
Steroid equivalency
- fluticasone is 2x as potent as beclomethasone
All children should have an asthma management plan
Inhaler technique should be reviewed by asthma/practice nurse
Clinical features of acute asthma exacerbation
Mild - SaO2 > 92% - vocalising without difficulty - mild chest wall recession - moderate tachypnoea Moderate - SaO2 < 92% - breathlessness - moderate chess wall recession Severe - SpO2 < 92% - PEFR 33-50% predicted - RR > 30 (over 5), > 40(under5) - too breathless to talk/feed - HR > 125 (over 5), > 140 (under 5) - use of accessory muscles - audible wheeze Life threatening - SpO2 < 92% - PEFR < 33% predicted - silent chest - poor respiratory effort - altered consciousness - agitation/confusion - exhaustion - cyanosis
Immediate management of acute attack
Oxygen - high flow to maintain sats between 94-98% Bronchodilators - inhaled SABA - via nebuliser if severe - inhaler and spacer for mild/moderate Ipratropium bromide (anti-muscarinic) Corticosteroid - short course (3 days) - oral prednisolone - IV hydrocortisone if vomiting or too unwell
Second-line management of acute asthma attack
IV salbutamol
Magnesium sulphate
Safe-discharge criteria for asthma attack
Bronchodilators are taken as inhaler device with spacer at intervals of 4-hourly or more (e.g. 6 puffs salbutamol via spacer every 4 hours)
SaO2 >94% in air
Inhaler technique assessed/taught
Written asthma management plan given and explained to parents
GP should review the child 2 days after discharge
Define bronchiectasis
Abnormal dilation of airways with associated destruction of bronchial tissue
- reversible in children
- commonly occurs as a result of CF
Epidemiology bronchiectasis
Prevalence of non-CF bronchiectasis is 172/ million children
Pathophysiology of non-CF bronchiectasis
Inflammatory response to a severe infection leads to structural damage within bronchial walls -> dilation
- scaring reduces number of cilia
- predisposes to further infections
Causes of non-CF bronchiectasis
Post infectious - Streptococcus pneumonia - Staphylococcus aureus - Adenovirus - Measles - Influenza virus - Bordetella pertussis - Mycobacterium tuberculosis Immunodeficiency - Antibody defects: agammaglobulinaemia, common variable immune deficiency or IgA/IgG deficiency - HIV infection - Ataxia telangiectasia Primary Ciliary Dyskinesia (PCD) - autosomal recessive genetic defect - reduced efficacy or complete inaction of bronchial cilia Post-obstructive - foreign body aspiration Congenital syndromes - Young’s syndrome: A rare condition associated with bronchiectasis, reduced fertility and rhinosinusitis - Yellow-nail syndrome: Another rare syndrome associated with pleural effusions, lymphoedema and dystrophic nails - Bronchiectasis occurs in around 40% of patients
Clinical features of bronchiectasis
Purulent sputum expectoration Chest pain Wheeze Breathlessness on exertion Haemoptysis Recurrent or persistent infections of the lower respiratory tract Finger clubbing Inspiratory crackles Wheezing
Investigations for bronchiectasis
CXR
- bronchial wall thickening or airway dilation
HRCT = gold standard
- bronchial wall thickening
- diameter of bronchus larger than that of accompanying artery - signet ring sign
- visible peripheral bronchi
- bilateral upper lobe ≈ CF
- unilateral upper lobe ≈ post-TB infection
- focal ≈ foreign body inhalation
Bronchoscopy
- reserved for children who have evidence of focal bronchiectasis on CT
Lung function tests
- normal in mild disease
- obstructive or mixed in severe disease
Investigations to determine underlying cause in bronchiectasis
Chloride sweat test - exclude CF FBC + leukocyte differential Immunoglobulin panel - immunoglobulin deficiency Specific antibody level - pneumococcal or Hib Ciliary brush if bronchoscopy performed HIV test Microbiological assessment - Pseudomonas spp ≈ CF
Management of bronchiectasis
Chest physio - learn mucus clearance techniques Abx in exacerbations Bronchodilators in those with a wheeze Follow up and monitoring of symptoms and lung funtion
Common infective causes of bronchiectasis exacerbations
Haemophilus influenzae
Streptococcus pneumoniae
Moraxella catarrhalis
Complications of bronchiectasis
Recurrent infection Life-threatening haemoptysis Lung abscess Pneumothorax Poor growth and development
Define bronchiolitis
Viral infection of bronchioles - smallest air passages in the lungs
- commonly caused by respiratory syncytial virus
Epidemiology of bronchiolitis
Usually affects children under age of 2
1/3 develop in 1st year of life
Mainly occurs during winter and spring
- 75% caused by RSV
Pathophysiology of bronchiolitis
Infection of lower respiratory tract - cell necrosis - inflammation - oedema - increased mucus secretion Leads to - hyperinflation - increased airway resistance - atelectasis - ventilation-perfusion mismatch
Risk factors for bronchiolitis
Being breast fed for less than 2 months
Smoke exposure
Having siblings who attend nursery or school - increased risk of exposure to viruses
Chronic lung disease due to prematurity
Prematurity
Immunodeficiency
Congenital/acquired lung and cardiac disease
Clinical features of bronchiolitis
Increasing symptoms over 2-5 days Low-grade fever Nasal congestion Rhinorrhoea Cough Feeding difficulty Tachypnoea Grunting Nasal flaring Intercostal, subcostal or supraclavicular recessions Inspiratory crackles Expiratory wheeze Hyperinflated chest Cyanosis or pallor
Differential diagnosis of bronchiolitis
Pneumonia Croup Cystic fibrosis Heart failure – VERY IMPORTANT Bronchitis Asthma Viral wheeze
Investigations for bronchiolitis
Nasopharyngeal aspirate or throat swab – RSV rapid testing and viral cultures
Blood and urine culture if child is pyrexic
FBC
Blood gas (ABG) if severely unwell – this may detect respiratory failure and the need for respiratory support, but should not be done routinely
CXR (only if diagnostic uncertainty or atypical course)
- Hyperinflation
- Focal atelectasis
- Air trapping
- Flattened diaphragm
- Peribronchial cuffing
Management of bronchilitis
Most managed at home - fluids, good nutrition and temperature control Severe referred to hospital - oxygen and NG feeding Palivizumab offered to high risk infants - vaccine
Criteria for urgent hospital referral for management of bronchiolitis
Apnoea Poor feeding Child looks seriously unwell Severe respiratory distress eg. grunting, marked recessions, respiratory rate >70 Central cyanosis Oxygen sats < 94% Hospital referral considered if - resp rate > 60 - inadequate fluid intake - clinical dehydration
Management of bronchiolitis
Primary care
- conservatively managed at home with adequate hydration and anti-pyrexial medication
Secondary care
- supportive care - O2 and NG feeding
- nebulised saline and nebulised adrenaline
- bronchodilators, corticosteriods and abx have no effect
Vaccine
- palivizumab offered to high risk infants
Complications of bronchiolitis
Hypoxia
Dehydration
Fatigue
Respiratory failure
Persistent cough or wheeze - very common and parents should be counselled that their child may cough for several weeks
Bronchiolitis obliterans – airways become permanently damaged due to inflammation and fibrosis
Prognosis of bronchiolitis
Usually lasts 7-10 days
Cough up to 6 weeks
Pathophysiology of COVID-19
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)
Main transmission via respiratory droplets - coughing, sneezing and talking
Risk factors for severe illness from COVID-19
Solid organ transplant recipients Certain cancers/those undergoing therapy Severe respiratory conditions - cystic fibrosis - severe asthma Immunodeficiency disorders Those on long term immunosuppressive therapies
Clinical features of COVID-19
Fever Dry cough Headache Sore throat Myalgia SOB Diarrhoea N+V Coryza Abdo pain Low O2 sats Increased RR Subcostal/intercostal recession Tracheal tug Tachycardia Crackles on auscultation
Features of Paediatric Inflammatory Multisystem Syndrome
Associated with SARS-CoV-2 infection Toxic shock syndrome Atypical Kawasaki disease Blood parameters consistent with severe COVID-19 Coronavirus positive or negative
