Respiratory Flashcards
What pathological signs are seen in asthma?
- Smooth wall hyperplasia
- Thick mucus plugs
- Thickened basement membranes (Deposition type IV collagen
- Mucosal odema (abnormal mucuciliary clearance
- Eosinophilia of submucosa and secretions
- increased mast cells in smooth muscle
What makes the diagnosis of asthma more likely?
Raised exhaled nitric oxide
What % of children with asthma will have a positive skin prick test to dust mite?
80%
What is the most common trigger of asthma exacerbation?
viruses- up to 85%. Most common is Rhinovirus
What blood test result might you get in children with asthma?
Otherwise unexplained raised eosinophilia
What percentage of children aged 1-4 years with wheeze DO NOT go on to have asthma at school age or later?
50%
How is preschool wheeze classified?
- Intermittent preschool wheeze (episodic, infrequent (>every 8 weeks)and viral)
- Frequent preschool wheeze (frequent, viral induced)
- Preschool asthma (multi-trigger wheeze)
What are the DDX of children with conditions characterised by cough? (other than asthma)
CF Pertussis Airway abnormality (tracheomalacia- more generalised, bronchomalacia- more localised) PBB Habitual cough
What are the DDX of children with conditions characterised by wheezing? (other than asthma)
Upper airway dysfunction
Inhaled FB with partial airway obstruction
Tracheomalacia
What are the DDX of children with conditions characterized by breathlessness? (other than asthma)
Hyperventilation
Anxiety
Poor ETT
How would you manage a child who is having wheeze triggered by viral illnesses less frequently than every 8 weeks (under 5 years old)?
Salbutamol only
How would you manage a child who is having wheeze triggered by viral illnesses more frequently than every 8 weeks (under 5 years old)?
Trial Flixotide for 8 weeks then reasses
How would you manage a child who is having wheeze triggered by viral illnesses AND in between illnesses (under 5 years old)?
Trial Flixotide for 8 weeks then reasses
How would you manage child >5 years old with suspected asthma?
Trial inhaled CCS. Reassess in 8 weeks. If no response check technique and review after 12 weeks of proper treatment. Consider PFTS
What would you see on spirometry is a child with asthma
Obstructive pattern
- concave loop
- FEV1 decreased
- FEV1/FVC reduced
Bronchodilator responsive of at least 12%
Normal DOES NOT exclude a dx of asthma
What causes a raised fractional exhaled nitric oxide level?
Suggests eosinophilic inflammation which may be caused by:
Asthma, eczema, allergic rhinitis, atopy, allergic bronchitis
Not diagnostic
What causes a lowered fractional exhaled nitric oxide level?
Smokers
Early phase of allergy
Some asthma phenotypes such as neutrophilic asthma
Why can you not use LABA’s without a combined inhaled corticosteroid
Can cause salbutamol resistance with a parodoxical bronchospasm resulting in increased mortality in scute exacerbations requiring Salbutamol
What kind of ICS are there?
Beclomethasone dipropionate (1/2 the strength of flixotide)
Beclamethasone dipropionate ultra fine (same strength as flixotide)
Fluticasone
Budenoside (1/2 the strength of flixotide)
What are the low dose ICS?
- low dose achieves 80-90% max efficacy in children
Beclomethasone dipropionate (1/2 the strength of flixotide) = 200mcg/day
Beclamethasone dipropionate ultra fine (same strength as flixotide) = 100mcg/day
Fluticasone = 100mcg/day
Budenoside (1/2 the strength of flixotide) = 200mcg/day
What is the next step in a child whose asthma is not controlled with a LOW dose ICS?
Add in a LABA
If >12 could use single maintenance and reliever therapy
When do you use Montelukast?
in <5 years old
- if frequent severe exacerbations (instead of ICS)
- or add frequent exacerbations not controlled with just ICS
in >5 year olds
- instead of ICS for frequent exacerbations
- or add if frequent exacerbations not controlled by STANDARD ICS + LABA
When do you step up to standard dose of ICS
If a child’s asthma is not controlled with a low dose ICS + LABA (or SMART if over 12yrs)
What are the STANDARD doses of ICS?
Beclomethasone dipropionate (1/2 the strength of flixotide)= 400-500ncg/day
Beclamethasone dipropionate ultra fine (same strength as flixotide) = 200mcg/day
Fluticasone= 200-250mcg/day
Budenoside (1/2 the strength of flixotide)= 400mcg/day
What is a HIGH dose of ICS?
Twice that of standard dose
What other preventors are there other than ICS in asthma treatment?
Leukotriene receptor antagonists - i.e montelukast
Mast cell stabilisers- cromones such as sodium cromoglicate and Nedocromil sodium
Theophylline
As a paediatrician, what add on’s would you consider of asthma Mx of children on max therapy?
Oral CCS Omalizumab (Anti-immunoglobulin E) Mepolizumba (Anti-leukin 5) Tiotropium Bromide (long acting muscarinc antagonist) Theophylline
What is Omalizumab?
Monoclonal antibody, prevents immunoglobulin E from binding to mast cells
SC injection
Used in severe uncontrolled asthma as a preventor
Given every 2-5 weeks depending on response
When do you prescribe a low dose ICS in children other than children with frequent wheeze?
In children 5 years or older who present with a severe exacerbation of wheeze regardless of what symptoms they have at baseline
What is the expected FEV1 of children with asthma depending on the control?
Well controlled - FEV1 >80% of predicted/personal best Not well controlled - 60-80% predicted -75-80% personal best Poor control - <60% predicted -<75% personal best
What is the average tidal volume of a child?
approx 6-7ml/kg
What is Inspiratory Capacity?
Maximum inspired effort (including inspired TV)
What is Expiratory reserve volume and the Inspiratory reserve volume?
ERV-max forced expiration EXCLUDING expired TV
IRV- max force inspiration EXCLUDING inspired TV
What is Elastance?
property of a substance to oppose deformation or stretching? = change in pressure/change in volume
What is compliance?
property of a substance to undergo deformation or stretching (the reciprocal of Elastance) = change in volume/change in pressure
-Compliance is the rate of change of volume in response to pressure
In a normal healthy lung at low volume, relatively little negative pressure outside (or positive pressure inside) needs to be applied increase lung volume. However lung compliance decreases with increasing volume. Therefore, as the lung increases in size, more pressure must be applied to get the same increase in volume
AFFECTED by FRC –> use to standardise
What is Resistance in respiratory?
amount of pressure required to generate flow across of gas across the airways
Cau use Poiseuille’s law
R = 8ln/πr^4 (l=length, n=viscosity, r = radius)
What happens to the resistance when the radius is halved?
resistance is inversely proportional to the radius^4
therefore 1/2 the radius = increase the resistance by 16
What diseases can have minimal respiratory distress even with severe respiratory failure (hypoxemia and acidosis)?
Any disease where they cannot mount a sufficient effort to appear in respiratory distress like neuromuscular diseases such as:
Gullian Barre syndrome
Myasthenia Gravis
What contributes to Pulmonary vascular resistance in the third trimester of pregnancy?
The tunica media of the pulmonary arteries in the fetus becomes more muscular
Why are young infants particularly susceptible to pulmonary vasoconstrictive stimuli (hypoxemia, acidosis, hypercarbia)?
The tunica media of the pulmonary arteries are more muscular.
In children and adolescence the pulmonary vascular resistance (PVR ) is approx 15% of the Systemic vascular resistance (SVR)
In day 3 of life the PVR is approx 50% of the SVR
The PVR only decreases to approx 15% after 2-3 months of life
What are the 2 main cytokines made by the alveolar macrophages that activate the inflammatory cascade?
Tumour necrosis factor- α
Interleukin-1β –> stimulate other cytokines, ROS, prostaglandins which stimulate WCC migrations into lung tissue which can cause injury to vessels and alveoli epithelium
What two findings can be found in SIDS autopsy which are higher than normal in explained deaths?
Petechial haemorrhage (68-95%) - and are more extensive than explained causes Pulmonary oedema
What is Leigh disease? (subacute necrotizing encephalopathy)
Inherited, rare, neurodegenerative conditions
Characterized by Psychomotor regression in the first year of life. Death occurs usually in 2-3 years from respiratory failure
Also get Vomiting, poor feeding, FTT, seizures, hypotonia, ophthalmoplegia, nystagmus
What is Brugada syndrome?
Cardiac channelopathy resulting in arrthymia SCN5a (sodium channel) receptor defect Arrythmia can be at rest or triggered by a fever No cure, but could use a pacemaker Occurs in children and in adults Genetic component Occurs in 1 -30/10,000 M>F Higher rates in Asian ethnicity
Why are nasal passages important in resistance to air flow?
contribute to 50% of resistance to air flow in normal children
Congenital severe narrowing can be caused by malformed nasal bones which are often associated with a high and narrow hard palate
What is choanal atresia?
Most common congenital anomaly of the nose
freq 1/1700 live births
Can be unilateral or bilateral bony (90%) septum between the nose and pharynx
Or can be a unilateral or bilateral membranous (10%) septum between the nose and pharynx
Most cases are a mixture of bony and membranous atresia
50-70% of children have other congenital anomalies - particularly CHARGE syndrome
10-20% of patients with CA have CHARGE
What is CHARGE syndrome?
C- coloboma
H- heart disease
A- atresia chonae
R- retarded growth and development or CNS anomalies or both
G- genital anomalies, hypogonadism or both
E- ear anomalies, deafness or both
Mutations in the CHD7 gene which is involved in CHROMATIN organization
What is Perforation of the nasal septum?
Generally acquired after birth secondary to infection
- Syphilis, TB, trauma (delivery)
- Rarely developmental
- CPAP nasal cannulae
If recognised early can be corrected with immediate realignment using blunt probes, cotton applicators and topical anaesthesia.
If late- surgical resection much later in life to avoid disturbance of mid face growth
What is Pyriform aperture stenosis?
Rare birth defect where the anterior opening of the nose is narrow secondary to overgrowth of the maxillary bone.
Cause of severe nasal obstruction and respiratory distress
Dx made by CT
Rx- surgery using a drill to enlarge the stenotic anterior bone apertures
