Resp Flashcards
Heiner Syndrome
Cows milk protein induced pulmonary haemosiderosis. Haemosiderosis ( haemoptysis, IDA, lung fibrosis) and chronic sinusitis and OME
Bilateral bilateral lymphadenopathy
TB LYMPHOMA SARCOID
EMBRYOLOGY
Embryonic – up to week 5 • Lung bud grows out from the fetal foregut • Single tube branches into two main bronchi Pseudoglandular – weeks 6–16 • Airways grow by branching (out to terminal bronchioles) • Cartilage and lymphatics appear from 10 weeks onwards • Cilia appear •Pulmonary circulation develops, arteries arising from the sixth branchial arches Canalicular – weeks 17–24 • Conventional architecture of the lung appears • Thinning out of distal cells in preparation for gas exchange • Further development of arterial circulation, and appearance of venous system • Surfactant synthesis begins • Lung fills with fluid (lack of fluid at this and later stage, e.g. with renal agenesis, leads to pulmonary hypoplasia) Alveolar sac – weeks 24–40 • Formation of the acinus (respiratory bronchioles, alveolar ducts and alveoli) • Cell differentiation into type I and II pneumocytes • Type I: • >90% of alveolar surface • Major gas-exchanging surface • Type II: • Thought to be the progenitor cell for type I cells • Produces surfactant which maintains surface tension and prevents alveolar collapse during respiration • Surfactant-associated proteins A and D (hydrophilic) involved mainly in innate immunity • Surfactant-associated proteins B and C (hydrophobic) important for surface tension
What are causes of false-positive and false-negative sweat tests?
- False-positive: adrenal insufficiency, nephrogenic diabetes insipidus, atopic dermatitis, familial cholestasis syndrome, Klinefelter’s, GSD, mucopolysaccharidosis, G6PD - False-negative: oedema, malnutrition, mineralcorticosteroid use
Discuss the differences between: - Congenital lobar emphysema - Bronchogenic cyst - CPAM - Pulmonary sequestration
- CLE: hyperinflation due to obstruction of developing airway, usually LUL, air-filled, herniates across mediastinum, compression of contralateral lung, usually symptomatic neonate. Usually symptomatic. Associated CHD. Resect only if symptomatic
- Bronchogenic cyst: usually mediastinal but can be anywhere, fluid-filled, sharply marginated. Risk infections. Remnant of primitive foregut
- CPAM: abnormality of branching morphogenesis of the lung, cystic and adenomatous elements, connection with tracheobronchial tree, can arise anywhere along it, blood supply from pulmonary circulation. Often asymptomatic, usually lower lobes. Resection as malignancy risk -
Sequestration: non-functioning mass of lung tissue, lacks communication with tracheobronchial tree, receives arterial blood supply from systemic circulation, usually lower lobes, dull to percuss with decreased BS, predispose to recurrent infections. Usually asymptomatic at birth. May have have continuous or systolic murmur over back. Surg resection or coil embolisation
What is the physiological dead space?
- The anatomical dead space + alveoli that aren’t involved. - The volume of the lung that does not eliminate CO2
Obstructive lung function tests
- Asthma, Bronchiectasis, Emphysema, Cystic Fibrosis - FEV1/FVC < 80% - FVC normal or decr - FEF 25-75 decreased - TLC normal or increased
Restrictive lung funcion tests
- Interstitial Fibrosis, Scoliosis, Obesity, Lung Resection, Neuromuscular diseases, Cystic Fibrosis - FEV1/FVC inc or normal, FVC decr, FEV1 decr - TLC decr - FEF 25-75 normal or decr
Fixed upper airway obstruction
- Tracheal stenosis, bilateral vocal cord paralysis, goitre ‐ Inspiration and expiration are limited equally - Flattened curve on insp and exp
Variable extrathoracic obstruction
‐ Limitation of inspiratory flow, flattened inspiratory loop ‐ e.g. Vocal cord paralysis, vocal cord dysfunction ‐ During expiration the vocal cords are passively blown aside ‐ During inspiration vocal cord moves passively with the inhalation and obstructs the glottis
Variable intrathoracic obstruction
‐ Flattening of expiratory limb ‐ e.g. Tracheomalacia ‐ During expiration there is loss of support resulting in resulting in a narrow trachea and reduced flow ‐ During forced inspiration the negative pleural pressure holds the floppy trachea open
Cause of low DLCO in obstructive disease?
Bronchiolitis obliterans, CF
DLCO in restrictive lung disease - low and normal causes?
- DLCO helps in differential diagnosis of restrictive lung disease - Low DLCO with reduced lung volumes suggests ILD, sarcoid, pneumonitis, pulm fibrosis - Normal DLCO associated with low volumes is consistent with extrapulmonary cause of restriction – pleural effusion, obesity, neuromuscular weakness, kyphoscoliosi
What is the FeNO, and causes of low and high tests?
- Fractional exhaled nitric oxide - Positive test suggests eosinophilic inflammation - Positive >35ppb = asthma, eosinophilic bronchitis, allergic rhinitis, eczema - Lower: smokers, CF/ciliary dyskinesia
Discuss the different CFTR genes in CF
- Class I (3%) - no protein e.g. G542X. Stop mutation, nonsense, short protein which is deleted, therefore no function. - Class II (90%) - no traffic e.e F508del. Abnormal folding, trafficking defect, therefore no traffic to cell membrane. - Class III (5%) - no function. e.g. G551D. Gating defect, protein can get to cell wall but Cl- cannot get out of cell. - Class IV - less function - Class V - less protein - Class VI - less stable
Modulator drugs in CF
- Class I (G542X) - nil - Class II (F508) - orkambi (lumacaftor and ivacaftor) >2yo in Aus, tricaftor (3 drugs, very new), symdeco (>12yo) - Class III (G551D) - ivacaftor - allows chloride through. >2yo in Aus. Can be used on homozygotes and heterozygotes. - Best results seen in tricaftor and ivacaftor - improved FEV1 > 10% (but inhaled TOBI also inc by 12%)
Newborn screening process for CF
- Immunoreactive trypsinogen - picks up to 1% levels (pancreatic duct blocked so enzymes cannot get into GIT therefore absorbed into bloodstream) - CF gene panel -> for 5 positive screens, 1 has true CF. 8% CF is missed (either IRT not in top 1% or has other gene mutations) - Sweat test: normal <30, abnormal >60, indeterminate 30-60
Most common CF pathogens in paeds population
- Staph > haemophilus > pseudomonas > MRSA > st. maltophilia - Pseudomonas increases through lifespan - MRSA increasing Aus > NZ
CF most common chronic infection in a) early childhood and b) later childhood?
- A = staph aureus. Not yet routine prophylaxis in NZ. MRSA ~15%, increasing. - B = pseudomonas aeruginosa. - If well then use PO ciprofloxacin + inhaled tobramycin - If unwell then use IV ceftazidime (NZ) or meropenem and tobramycin (Aus). - Causes intense inflammation, develops biofilm, difficult to eradicate. Associated with poorer prognosis and lower survival. - If chronic pseudomonas (>50% samples of 4/year) then use azithromycin Mon/Wed/Fri
Discuss bronchiolitis obliterans
- After an insult to the lower respiratory tract and leads to chronic obstructive lung disease from fibrosis of the small airways - Post viral: adenovirus, mycoplasma or inflammatory disease (e.g. JIA, SLE) or graft vs. host disease or lung transplant - Chronic cough, SOB, sputum production and wheeze. Hypoxemia and crackles - CXR: variable, hyperlucency and patchy infiltrates. - PFTS: obstructive, variable response to salbutamol -Tx: supportive, treat infections, O2, may require steroid course, immunosuppressants (tacrolimus, cyclosporine, macrolide antibiotics)
Discuss CF-related diabetes
- Will develop with time - Often deterioration in lung function associated - Decreased insulin production + insulin resistance + normal effect of insulin reduced - Screen with OGTT and HbA1c (unreliable) and confirm with continuous glucose monitoring - Some will require small amount of insulin
Airway clearance in CF
- Pulmozyme - recombinant human deoxyribonuclease I - an enzyme which cleaves DNA, reduces sputum viscoelasticity, improves lung function and reduces exacerbations - Hypertonic saline nebs 7% - draws water into airways and thins secretions, improves FEV1 and reduces exacerbations - Physio - Exercise
Poor prognostic factors in CF?
- Malnutrition - Pseudomonas - B. cepacia - CF-related diabetes - Frequent exacerbations - Female, especially teenage
Most common chronic infection in bronchiectasis?
- Haemophilus influenzae. Note: staph is rare, therefore if present need to check for CF - Moraxella and strep pneumoniae intermittent
Discuss the steps of asthma therapy
- 1: SABA (salbutamol) - 2: SABA + low dose ICS (fluticasone, flixotide) - 3: <5y - leukotrine receptor antagonist (montelukast) >5y - SABA + ICS + LABA (seretide, salmeterol) >12y - SMART therapy with symbicort (budesonide/formeterol) - 4: increase ICS dose, add montelukast >5y - 5: increase ICS dose -> always check compliance, spacer, lung function tests - LABA monotherapy unsafe(theory reduction in B2 density). Not used <4y
Discuss the emryological lung stages
- Embryonic (26 days to 6 weeks gestation) - Pseudoglandular (6-16 weeks) - major lung elements, except for those required for gas exchange (e.g. alveoli) have appeared. - Canalicular (16-26 weeks) - bronchial lumens enlarge and lung tissue becomes vascularised. Bronchioles and alveolar ducts develop from terminal bronchioles. - Saccular (26 weeks to birth) - specialised cells appear (type 1 and type II alveolar cells) and produces surfactant. - Alveolar (birth to 3 years) - terminal saccules, alveolar ducts, and alveoli increase in number.
Diagnostic findings in primary ciliary dyskinesia?
- Abnormal cilia - absent dynein arms, translocation of central tubules - Ciliary beat frequency low - Low exhaled nasal nitric oxide
Use of osteltamivir
- Neuraminidase inhibitor - For influenza - Reduces viral spread in airways if given in first 48 hours of symptoms
Defects in IF-gamma and IL-12 pathways predisposes to
MYCOBACTERIAL infections (TB)
Mantoux cut-off values
- >15mm positive in everyone - >10mm if recent immigrant, children <4y, high risk - >5mm if HIV, recent TB contact, abnormal CXR - False negatives in young, immune deficiency, HIV/flu/measles - T-cell mediated reaction
Treatment of TB
- Chemoprophylaxis in infection - isoniazid 6m +/- rifampicin 3m - Chemotherapy (disease) - isoniazid + rifampicin for 6m + pyrazinamide + ethambutol for first 2m - Total 12m if meningitis. - 6-8 weeks corticosteroids if meningitis/pericarditis/miliary TB - Need sputum culture of gastric aspirates prior to starting therapy - AFB, Ziehl Neelsen stain
Side effects of TB meds
Peripheral neuropathy, liver derangements, orange urine/tears (rifampicin) visual disturbance (ethambutol)
Discuss pneumocystis jiroveci
- Tachypnoea, resp distress, fever, bilat crackles, hypoxia - CXR: bilat interstitial and alveolar shadowing, ground glass/crazy paving on CT - Yeast-like fungus - Dx: bronchoalveolar lavage, blue/silver stain - Causes: SCID, HIV, DiGeorge, hyper IgM, oncology - Tx: high dose cotrimoxazole (causes pancytopenia, fever, rash), +/- steroids, surfactant if I+V, prophylaxis post treatment - Can get dual infection with CMV as cause of pneumonitis
Discuss lymphocytic interstital pneumonitis
- Seen in HIV or immunodeficiency, EBV - Marked lymphadenopathy, parotid hyperplasia, HSM, falling CD40 count, chronic cough, hypoxia, clubbing, ILD - Tx: nil if well, may respond to steroids
Discuss pulmonary haemosiderosis
- Triad of iron-deficiency anemia, hemoptysis, and multiple alveolar infiltrates on chest radiographs - Repeated pulm haemorrhage leads to accumulation of hemosiderin in alveoli - Can have haemoptysis, episodic fever, SOB, wheeze - CXR: normal or patchy - Diagnosis via BAL - hemosiderin-laden macrophages - Tx: acute O2, transfusion. Chronic - steroids, hydroxychloroquine, immunosuppression - Can be associated with SLE, GPA, Goodpasture’s, cardiac abnormalities, or be idiopathic - Can be associated with Cow’s milk hypersensitivity
What stage of sleep does OSA worsen in?
REM - irregular breathing, inc upper airways resistance, low tone, decreased tidal volume
When do parasomnias occur?
- Partial awakening from N3 deep sleep - Usually 60-90 min after going to sleep - 1 or 2 per night - Usually +ve family history
Treatment of periodic limb movement?
- Associated with partial iron deficiency in CNS - treat with iron to keep systemic ferritin >50-75 to force iron into brain
Periodic limb movements vs. restless legs
- PLMD: repetitive (usually every 20 to 40 sec) twitching or kicking of legs or arms during sleep. Interrupted nocturnal sleep or excessive daytime sleepiness. - RLS: irresistible urge to move the legs, arms, or, body, usually accompanied by paresthesias +/- pain. Inc when sedentary, evening time. To relieve symptoms, patients move the affected extremity by stretching, kicking, or walking. Difficulty falling asleep, repeated nocturnal awakenings, or both.