Respiratory Flashcards
How many ribs are normal to visualise on a paediatric CXR?
6 anterior
9 posterior
Why is a caesarean a risk factor for respiratory distress syndrome?
Birth contractions during vaginal labour result in increased levels of glucocorticoids which aid lung maturation and surfactant distribution
Why is maternal diabetes mellitus a risk factor for respiratory distress syndrome?
Insulin inhibits surfactant production
What are the x-ray features of an infant with respiratory distress syndrome?
Reticulogranular ground-glass densities (fibrinous exudates from epithelial damage)
Air bronchograms (tubular outline of an airway made visible by filling of the surrounding alveoli by fluid or inflammatory exudates)
Low lung volumes (airway collapse)
What is the main marker of foetal lung immaturity assessed by amniocentesis for respiratory distress syndrome?
Lecithin-sphingomyelin ratio <1.5
The amount of sphingomyelin in the amniotic fluid stays consistent during pregnancy
The lecithin concentration (the major component of surfactant) varies depending on the amount of surfactant present
What is the major long-term complication of prolonged mechanical ventilation and oxygen in neonates with respiratory distress syndrome?
Bronchopulmonary dysplasia
Chronic lung disease primarily found in premature infants exposed to prolonged mechanical ventilation and oxygen therapy for neonatal RDS
How is neonatal respiratory distress syndrome prevented?
Antenatal corticosteroid therapy administered to the mother
Stimulates infant lung maturation
What is the most common cause of respiratory distress in term infants?
Transient tachypnoea of the newborn
What causes transient tachypnoea of the newborn?
Delay in the resorption of lung fluid
Mostly occurs in those born by caesarean section
What is the medical management for mild croup?
Prednisolone or oral dexamethasone
Reduces airway swelling, long-lasting
What is the medical management of severe croup?
Inhaled adrenaline (fast onset)
AND
Dexamethasone
Haemophilus influenzae type b typically caused which disease?
Epiglottitis
What is the management of bronchiolotis?
Supportive
What is the characteristic feature of laryngitis?
Hoarseness
Non-specific
Preterm infants suffer what due to insufficient surfactant production and/or distribution?
Neonatal respiratory distress syndrome
Why can infants with respiratory distress syndrome develop hyaline membrane disease
Hypoxemia and hypercapnia → vasoconstriction of the pulmonary vessels and acidotic metabolism → intrapulmonary right to left shunt → increased permeability due to alveolar epithelial damage → fibrinous exudation within the alveoli → development of hyaline membranes in the lungs (hyaline membrane disease)
Which type of asthma is typically triggered by allergens or environmental antigens?
Extrinsic (allergic)
Which type of asthma is typically triggered by drugs, respiratory tract infections, physical exertion and cold air?
Intrinsic (non-allergic)
What is the methacholine challenge test?
Used for diagnosing asthma when spirometry is unclear or diagnosis in doubt
Methacholine is administered and FEV1 is monitored for a drop
What is fluticasone?
An inhaled corticosteroid
What is montelukast?
Leukotriene-receptor antagonist
Decreases bronchoconstriction and inflammation
What is the MoA of omalizumab?
Anti-IgE antibody that binds to serum IgE
- reduces IgE binding to basophils and mast cells
- reduces surface expression of the IgE receptor on basophils and mast cells with long-term use
What is status asthmaticus?
An extreme asthma exacerbation that does not respond to initial treatment with bronchodilators
What is the definition of pulsus paradoxus?
Inspiratory fall in SBP > 10 mmHg
What normally occurs to BP during inspiration and why?
Decreases
Inhalation → decrease in intrathoracic pressure → blood flows into the RV + blood pools in the lungs → compression on the LV → decreased stroke volume and peripheral pulses
Why does asthma cause pulsus paradoxus?
BP normally drops with inspiration due to increased RV volume and blood in the pulmonary vasculature that compresses the LV
During epsiodes of airway resistance, negative intrathoracic pressure seen on inspiration is greater than normal so this physiological response is exaggerated
What is the most common cause of the common cold?
Rhinovirus
Vesicles on the posterior pharynx are characteristic of which disease?
Herpangina (coxsackie)
An amoxicillin-induced rash is characteristic of which disease?
EBV/infectious mononucleosis
What does a monophonic wheezes suggest?
Fixed obstruction e.g. foreign body, tumour
List 4 potential complications of sinusitis
- Periorbital/orbital cellulitis
- Meningitis
- Encephalitis
- Cavernous sinus thrombosis
- Cerebral/subdural/epidural abscess
- Osteomyelitis of the frontal bone
What anitbiotic is given for sinusitis when indicated?
Amoxycillin
Only in severe or protracted illness
Which 3 agents are most commonly responsible for acute bacterial rhinosinusitis?
- Streptococcus pneumoniae*
- Haemophilus influenzae*
- Moraxella catarrhalis*
Why is a normal or high PaCO2 during an asthma attack concerning?
Normally: hyperventilation → low PaCO2
The PaCO2 will increase if the patient’s respiratory muscles are fatiguing → respiratory failure
What is the clinical course of bronchiolitis?
Begins with upper respiratory tract symptoms
Lower respiratory symptoms and signs develop on days 2-3
Symptoms peak on days 3-5
Resolve over the next 2-3 weeks
What are the three best ways of assessing disease severity in a child with bronchiolitis?
- O2 saturations
- Work of breathing
- Feeding
What is the salbutamol dose for children having an acute asthma attack?
0-5 years/<20kg: 6 puffs
6+ years/>20kg: 12 puffs
What is the monoclonal antibody that binds IgE?
Omalizumab
What is the definition of good asthma control?
All of
Daytime symptoms ≤2 days per week (lasting only a few minutes and rapidly relieved by rapid-acting bronchodilator)
No limitation of activities
No symptoms during night or when wakes up
Need for reliever ≤2 days per week
What is the definition of partial asthma control?
Any of
Daytime symptoms >2 days per week (lasting only a few minutes and rapidly relieved by rapid-acting bronchodilator)
Any limitation of activities
Any symptoms during night or when wakes up
Need for reliever >2 days per week
What is the definition of poor asthma control?
Either of
Daytime symptoms >2 days per week (lasting from minutes to hours or recurring, and partially or fully relieved by rapid-acting bronchodilator)
≥3 features of partial control within the same week
What is the stepwise escalation of asthma medications in children?
- SABA as needed (all children)
- ICS (low dose)
- ICS/LABA (low dose)
- ICS/LABA (high dose)
- Referral
What is the most notable adverse effect of montelukast?
Aggressive behaviour
What is the MoA of cromoglycate?
Inhibits release of inflammatory mediators from mast cells
How does adrenaline work to relieve airway obstruction in patients with croup?
Constricts precapillary arterioles + decreases capillary hydrostatic pressure → fluid reabsorption → improvement of airway oedema
What O2 saturations correspond with mild, moderate and severe asthma?
Mild: >94%
Moderate: 90-94%
Severe: < 90%
A low-pitched, continuous wheeze which usually clears after coughing is characteristic of which adventitial sound?
Rhonchi
Often resembles snoring
https://www.youtube.com/watch?v=nokZ5sNt3fA
What is the second most common cause of bronchiolitis in children?
Rhinovirus
What is the mechanism of sodium cromoglycate?
Inhibits release of inflammatory mediators from mast cells
What is the difference between aminophylline and theophylline?
Aminophylline = managing asthma exacerbations
Theophylline = preventor
When is aminophylline used during asthma exacerbation management?
Inadequate response to salbutamol
Evidence is limited for children and non-existent for adults
What is the major adverse effect of aminophylline?
Vomiting
Also giddiness and cardiac arrythmias
When is tiotropium used for asthma?
Alongside ICS + LABA when asthma remains moderate/severe
In consultation with a specialist
What is the role of azithromycin for asthma?
Can be used as a preventer when asthma remains moderate/severe despite treatment with ICS + LABA
Anti-inflammatory and anti-microbial
What is the role of magnesium sulfate in asthma management?
Can be used acutely when response to a SABA is inadequate
What is the role of adrenaline in acute asthma management?
Not routinely used
Only when salbutamol cannot be given to a patient with respiratory arrest or when anaphylaxis is suspected
What is the difference between CPAP and BiPAP?
CPAP = PEEP only (keeps airways open to reduce respiratory effort)
BiPAP = PEEP + PIP (breathing for infant)
What is a Harrison’s sulcus?
Horisontal groove along the lower border of the thorax corresponding to the costal insertion of the diaphragm
Associated with chronic lung disease e.g., severe asthma
What is bronchomalacia?
Collapsable airways
Causes: congenital absense of cartilage, extrinsic airway compression, acquired narrowing after infection or lung/heart transplant
What are the clinical features of bronchomalacia?
Fixed expiratory wheeze
Chronic cough
Recurrent infections
Exercise intolerance
Respiratory distress
Apnoeas
When should oxygen therapy be given to children with bronchiolitis?
SpO2 persistently < 90%
At what rate do you give oxygen for bronchiolitis?
1L/kg/minute
What effect can ventolin have on BGLs?
Hyperglycaemia
What electrolyte abnormality may occur with salbutamol?
Hypokalaemia
A patient is given ventolin and their RR increases. Why?
Side effect of the medication
A patient is given ventolin and their SpO2 decreases. Why?
Shunts open → areas of poor perfusion are opened
What is chronic suppurative lung disease?
Children clinically appear to have bronchiectasis but without consistent radiographic features
Chronic wet cough, recurrent chest infections, clubbing, growth failure, chest wall deformity, chronic hypoxemia, pulmonary hypertension
What is the most common cause of pneumonia in children < 5 years?
RSV (commonly an extension of bronchiolitis)
More commonly viruses than bacteria
- Influenza A + B*
- Human metapneumovirus*
- Parainfluenza virus*
Which organisms cause aspiration pneumonia?
Anaerobic oral flora
- Peptostreptococcus* + other anaerobic streptococci
- Fusobacterium* spp
- Bacteroides* spp
- Prevotella melaninogenica*
What dose of prednisone is given in acute asthma?
1mg/kg (max 50mg) for 3-5 days
Begin within 1st hour
Use hydrocortisone or methylprednisolone is oral is unable to be tolerated
What is Cheyne-Stokes respiration?
A breathing pattern that cycles between apnoea and hyperpnoea
A type of central sleep apnoea
What are the types of apnoea?
Central
Obstructive
Mixed
What are some of the extra-pulmonary manifestations of myoplasma pneumonia?
Erythema multiforme
Fatigue
Headache
Sore throat
Myalgia
How is mycoplasma pneumonia treated?
Tetracycline (doxycycline)
Or a macrolide (azithromycin, clarithromycin)
How is pertussis treated?
Azithromycin/clarithromycin
Within 3 weeks of cough onset
What CXR findings are suggestive of mycoplasma/chlamydia pneumonia?
Unilateral lower lobe interstitial pneumonia
Looks worse than presentation
What is infrequent intermittent asthma?
Symptom-free for at least 6 weeks at a time
Flare-ups up to once every 6 weeks on average but no symptoms between flare-ups
What is frequent intermittent asthma?
Flare-ups more than once every 6 weeks on average but no symptoms between flare-ups
What is persistent asthma?
Asthma that has symptoms between flare ups
Can be mild, moderate or severe
During an asthma exacerbation, when should a child see a doctor/come to hospital?
3-4 hourly Ventolin: see a GP
< 3 hourly Ventolin: come to hospital
On spirometry, what result demonstrates reversibility with bronchodilators?
FEV1 increases > 12% 10-15 minutes after a bronchodilator
