Respiratory Flashcards
Which organisms most commonly colonise the airways of adolescent patients with cystic fibrosis?
Staph aureus (50-80% and Pseudomonas aeruginosa (70-80%)
Interaction between meconium and surfactant?
Meconium deactivates surfactant and may also inhibits surfactant synthesis
Bronchiolitis obliterans overview
Occurs following an insult to the lower respiratory tract from infectious or non-infectious causes, leads to chronic obstructive lung disease from fibrosis of the lower airways
Clinical features of bronchiolitis obliterans
Cough, fever, dyspnoea, cyanosis, chest pain, respiratory distress
Chronic symptoms include chronic cough, dyspnoea, sputum production and wheeze
Spirometry findings in bronchiolitis obliterans?
Obstructive pattern, with variable response to inhaled bronchodilators
Management of bronchiolitis obliterans
Supportive
Antibiotics for secondary infection
Supplemental oxygen if required
Corticosteroids
Immunomodulatory agents in post transplant patients
Postnatal clinical presentation of CPAM?
Respiratory distress in the newborn period, due to pulmonary hypoplasia, mediastinal shift, spontaneous pneumothorax and/or pleural effusions secondary to hydrops
Causes of acquired bronchiectasis
Arises from obstruction of the airways, due to repeated infections, inflammation, impacted mucus and poor ciliary clearance, leading to the airways being susceptible to colonisation
Pathophysiology of bronchiectasis
A cycle of a chronic inflammatory response is triggered and leads to bronchiole remodelling (dilation and increased wall thickness).
The cycle of chronic infection, inflammation and difficulty clearing secretions propagates airway injury and remodelling
Clinical features of bronchiectasis
Chronic cough with copious purulent sputum, crackles, wheeze, clubbing, anorexia, poor weight gain
What is the main determinant of intrathoracic airway resistance in normal children?
Lung elastic recoil
Best investigation to evaluate CPAM postnatally (if not visible on CXR?
High resolution CT of the chest
After CF, what is the next most common disease affected by allergic bronchopulmonary aspergillosis?
Persistent asthma (1-2%)
NAVA: with flow triggered ventilation and volume guarantee of 3ml/kg, what will occur if there is a decrease in the baby’s lung compliance?
If lung compliance decreases, the breaths will require a higher peak inspiratory pressure to be able to achieve the same volume
CXR findings of subglottic narrowing and a ragged appearance of the trachea suggest?
Bacterial tracheitis
Most common pathogens causing bacterial tracheitis
Staph aureus, haemophilus influenza and moraxella catarrhalis
Physiological changes seen in bacterial tracheitis?
Obstructive airway disease due to the formation of a pseudomembrane, pus and mucosal sloughing
‘Thumb print sign’ on lateral neck XR is suggestive of?
Epiglottitis
The most common CF gene mutation is a result of?
The most common is change in F508, which is a codon deletion on the CFTR gene (class II defect)
Accounts for 70% of all mutations and results in severe disease
What is the most likely morbidity for patients with moderate chronic upper airway obstruction?
Decrements of memory and attention (leading to poor school performance)
Overview of subglottic haemangioma
Rare cause of stridor in children
Strongly associated with cutaneous haemangiomas
Usually present after the first few weeks of life due to development of symptoms with enlargement of the haemangioma
Effect of carbon monoxide on the oxyhemoglobin dissociation curve?
Shifts to the left - further hypoxia as the Hb is unable to offload oxygen
Overview of toxic effects of carbon monoxide
Displaces oxygen from Hb binding site, decreasing O2 carrying capacity of the blood:
- CO has 250 fold increased affinity for Hb than oxygen
- CO shifts dissociation curve to the left
- reacts with myoglobin to further impair oxygen uptake by reducing facilitated diffusion of oxygen into muscle
Presentation of pertussis in older children?
Prolonged, persistent, paroxysmal cough often confused with acute bronchitis
- associated with leukocytosis due to lymphocytosis
Overview of congenital lobar emphysema
Presents in neonatal period, many noted prenatally
Clinical features - range from mild tachypnoea and wheeze to severe dyspnoea and cyanosis
Affects upper and middle lobes, left upper lobe most common
Affected lobe is nonfunctional due to over distension, which may cause atelectasis of the ipsilateral normal lung
Mediastinal shift is due to overdistension
Which interleukins are markedly increased during COVID-19 infection?
Cytokines IL6 and IL10 are known to increase during COVID-19 infection, as part of the proinflammatory immune response
SpO2 of 90% equal what PaO2?
60mmHg
PaO2 40mmHg = SpO2 70%
PaO2 50mmHg = SpO2 80%
PaO2 60mmHg = SpO2 90%
How is diagnosis of latent TB made?
Positive tuberculin skin test or Interferon Gold and no evidence of TB disease
These patients are not unwell or infectious but are at risk of reactivation, therefore need treatment
Decreased serum IgG, +/- decreased IgA and IgM in infants >6 months?
Transient hypoglammaglobulinaemia of infancy (B cell deficiency)
- normal to near-normal antibody responses to protein immunisations
Which measure on spirometry is the most sensitive in children with small airways disease?
Forced expiratory flow 25%-75% (FEF 25%-75%)
- also known as maximum mid-expiratory flow rate, considered to represent flow in smaller airways
- the most effort independent portion of the curve
- useful measurement of milder obstruction
- can be reduced when patient is symptom free and in the presence of normal FEV1/PEFR
Which measure on spirometry correlates well with the severity of obstructive diseases?
FEV1
Pulmozyme (dornase alpha) indication and MoA?
= highly purified solution of recombinant human deoxyribonuclease I, an enzyme which selectively cleaves DNA
Inhaled solution used for CF
Anti-neutrophil, reduces gas trapping, improves airway clearance and improves CT findings
Characteristic features of primary ciliary dyskinesia?
Chronic bronchiectasis
Nasal polyposis
Recurrent otitis media
Recurrent sinusitis
Infertility/subfertility
What is Kartagener’s syndrome?
Occurs in 50% of patients with PCD
- visceral situs inversus, chronic sinusitis and bronchiectasis
At what stage of lung development is the earliest time when surfactant is produced?
Canalicular (weeks 16 to 24) - bronchioles are produced, cells lining respiratory structures begin to differentiate to form type I and type II pneumocytes. Once the cells have differentiated, they begin to secrete small amounts of surfactant
Order of lung development?
Embryonic (weeks 4-7)
Pseudoglandular (weeks 7-16)
Canalicular (weeks 16-24)
Saccular (weeks 24-40)
Alveolar (weeks 36 to 8 years postnatally)
Lung development - embryonic stage?
Weeks 4-7
Lung buds originate as an outgrowth from the ventral wall of the foregut, where lobar division occurs
At the end of this stage, the first segments appear in the five lobes of lung
Lung development - pseudoglandular stage?
Weeks 7-16
Conducting epithelial tubes surrounded by thick mesenchyme are formed. Lungs have the appearance of a gland-like structure, this stage is critical for the formation of conducting airways.
Lung development - canalicular stage?
Weeks 16-24
Bronchioles are produced, increasing numbers of capillaries are in close contact with cuboid epithelium and the beginning of alveolar development
Cells lining respiratory structures begin to differentiate to form type I and type II pneumocytes. After the cells have differentiated, they begin to secrete surfactant
Lung development - saccular stage?
Weeks 24-40
Major growth and maturation of the respiratory system occurs from week 24. More alveolar precursors develop and larger quantities of surfactant are produced. Alveolar ducts, air sacs and pulmonary capillaries are developed, to create a large SA for gas exchange.
At about week 28, enough alveolar precursors have matured, which increases the chance of survival of a baby born prematurely at this stage