RMS Quiz 1 Pulmonary Delivery Flashcards
What is cystic fibrosis characterised by
Thick, sticky mucus production that clogs airways and ducts and is treated using mucolytics (breaks down mucus)
What 2 types of aerosols do we have
1) suspension = solid particles a suspended in air
2) solution = liquid particles suspended in air
What does the upper respiratory tract consist of
Nose, throat, pharynx and larynx
What does the lower respiratory tract consist of
Trachea, bronchi, bronchioles and alveoli regions
The trachea branches into 2 bronchi, which one is wider and more likely to receive inhaled material
RIGHT subhnlh
Why is it highly likely that particles will deposit on airway walls
Because the airways are tortuous
What size must particles be to reach the bronchioles
<5 microns
What size do particles have to be to reach the alveoli
<2 microns
How many divisions are there from the trachea to the alveoli
23
How does particle delivery differ in healthy vs diseased lungs
Particles should be less than 5 microns for delivery to healthy lungs however for diseased lungs they should be less than 3 microns approx because they’ll be more narrow
As you further into the lungs does
a) radius
b) resistance
c) air flow speed + how would this differ for diseased lungs
Increase or decrease
a) increases
b) increases
c) decreases (decreases even more)
How is aerodynamic diameter calculated, da
da = dg(geometric diameter) X p(density of particle)^0.5
What are the 3 mechanism of deposition
1) Inertial impaction
2) sedimentation
3) Diffusion (Brownian motion)
What’s inertial impaction
Particles hit the airway walls early only because they are too large (greater than 5 microns) occurs in the mouth and throat mainly
What does inertial impaction depend on
Particles momentum, position and angle of bifurcation
What’s sedimentation
When particles are small enough (1-5 microns) to be suspended in air through the tortuous pathway into the peripheral parts of the lung but eventually due to resistance and gravity settle in the peripheral airways
What’s diffusion in relation to particle deposition
When particles are too light (less than 1 micron) to settle so they diffuse into the peripheral lung and alveoli space
They won’t settle due to gravity bc they’re too light but they eventually settle due to the Brownian motion
How does clearance in lung occur in the upper airways (central)
Via mucociliary escalators = particles that deposit onto the mucus, the cilia sweep them towards the back of the throat to be swallowed and ingested
And via drug dissolution = drug dissolves and passes the thick mucus layer (less likely to occur)
How does drug clearance in the alveolar region (peripheral) occur
Via macrophage clearance = macrophages engulf foreign substance and transport it to the nearest mucociliary escalators and deposit it where it is brushed up and swallowed (occurs with drugs like beclomethasone that are insoluble)
What’s the advantages and disadvantages of local drug delivery (pulmonary)
Adv:
- drug delivered directly to target organ so lower doses can be administered for optimal effect
- rapid onset of action
- fewer side effects
- non invasive in this case for pulmonary delivery
Disadv:
- varying efficacy due to patients with bad inhaler technique (dependant on patients inhaler technique)
- difficult in breath coordination
- corticosteroids can suppress immune system
- throat irritation is possible from bad technique
What are the advantages and disadvantages of systemic pulmonary drug delivery
Adv:
- very rapid onset of action
- circumvents first pass metabolism
- non invasive
- good for drugs that degrade easily
Disadv:
- low efficacy of delivery
- patient may find it difficult to use and thus receive no treatment benefit
What are some challenges of pulmonary vaccines
The vaccine agents are unstable in aqueous environments but this may be overcome with spray-drying
Brielfly go over the lung first and second line immune system defence
First line = mucus, cilia, tight junctions and surfactant
Second line = innate immune system (alveolar macrophages) & adaptive immune system (B,T cells)
How old are a) infants, b) pre-schoolers c) school children and d) adolescents
a) newborn to 2 yrs b) 2-5yrs c) 5-11 yrs d) 11- 16/18 yrs
What’s lung development like in infants
Alveoli are rapidly forming at this stage, they DO NOT breathe through their mouth at this time (small mouth and large tongue - can lead to breathing issues when nose is blocked), narrow airways and thus high resistance, high breathing frequency and they have laryngeal braking (controls exhalation so it isn’t prolonged too much)
What’s lung development like in. Pre schoolers
Increased lung volume due to alveoli enlargement, still mostly nasal breathing (diaphragm driven), airways still narrow and have high resistance, tongue still larger than mouth and high breathing frequency
What’s lung development like in school children
Girls have larger airways than boys here, airway diameter finally increases so resistance decreases, slower breathing frequency and tongue and mouth ratio decreases
What’s lung development like in adolescence
Completed growth, boys airways are now larger than girls, large airways = less resistance
What ages groups is it difficult to do lung function test
Infants and preschoolers
What’s a nebuliser + advs & Disadv
Mist breathed suing face mask - popular for use in infants as no coordination or effort is required
Adv: takes into account infants predominant nasal breathing
Disadv: bulky device only available at hospitals
What can achieve the same therapeutic outcome as a nebuliser
PMDI WITH a nebuliser - bc the child can breath tidally as it gives time for the droplets to evaporate
BUT NOT RECOMMENDED FOR CHILDREN UNDER 4
Can ,argue spacers be used in infants and children with small tidal volumes
NO
Why is a tight seal on the nebuliser face mask important
A small leak can decrease aerosol delivery efficiency
What percentage correlates to good and bad inhaler technique
Good = 20%
Bad = 80%
Why is paediatric inhaler design difficult
Inhalers are made for adults then adapted for children bc there’s a lack of clinical data (drug trials would need to be carried out on children = not ethical) and lack of paediatric deposition models
