Nebulisers

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  • Created by: LBCW0502
  • Created on: 16-03-19 14:31
Which device was the first medical inhaler?
The nebuliser
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Describe the devices used in 1790s
Bulky devices used, made pots (for chemistry instruments). Large jar (heat sensitive), nasal (inhalation), shape/bulkiness didn't change, fragile
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Describe the devices used in 1930s
Different systems. Atomisers. Perfume industry developed. Used system of pump to spray perfume (squeeze liquid through tube for particles to be dispersed, aerolisation) - applied to inhalation (particles were not small enough) - start of nebulisers
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What are the two types of nebulisers?
Jet/pneumatic nebulisation and ultrasonic nebulisation (newer devices are bigger, need battery pack/energy source)
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How does the jet nebulisation work? (1)
Compressed gas source (produced by energy source, high speed), comes through tube, narrowing. Venturi effect (link between velocity of airstream and pressure inside device). Velocity increased in narrow tube. Equilibrium in system/pressure drops
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How does the jet nebulisation work? (2)
Tornado formed, particles of liquid become strips of liquid, falling apart into small droplets. If droplets not small enough, there is a baffle system to create turbulence (make particles smaller). Patient inhales aerosol droplets
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How does the jet nebulisation work? (3)
Constant production of aerosol (downside/wasted/can be deposited in face or clothes, not breath actuated). Particles become in range of 1-5 microns. Advantage (no coordination required, inhale slowly and good deposition in lower airways/reproducible)
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How does the ultrasonic nebulisation work? (1)
Battery pack/energy device (creates electrical signal). Piezoelectric crystal (create change in electrical energy into mechanical vibration). Create ultrasonic waves. Small droplets coming apart. Baffles (extra turbulence, smaller particles)
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How does the ultrasonic nebulisation work? (2)
Particle size depends on ultrasonic waves/vibrations (weaker - larger particles, stronger - smaller particles). Particles ranges of 1-5 or 3-5 microns. Constant production of mist (inhaled by patient, no coordination issues, no issue with dispersion)
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What is the disadvantage of both types of nebuliser?
Large volumes of liquid required (solution, 5 mL, most is wasted). Bulky and expensive devices
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What is the advantage of both types of nebuliser?
Good deposition of particles in lower area of the lungs. Particles produce reproducible size distribution. No coordination issues. No air flow issues
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Which group of patients use nebulisers?
CF patients (not as common for patients with asthma/COPD, sometimes used for corticosteroid therapy). For mucolytic compounds or antibiotics (use once a day).
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Describe features of modern nebulisers
Small amount of liquid (500 microlitres, dose) below mesh. Vibrations pressed through. Liquid droplets pass through pores (smaller pores, smaller droplets). Device is small, little wastage of drug
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Describe features of modern nebulisers which are breath actuated
Sensor (detects change in pressure when patient is breathing in or out). Sensor produces mist when patient is breathing. When patient is not breathing, pressure will drop and sensor stops producing mist. Little wastage of drug
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Describe features of modern nebulisers which are adaptive breath controlled
When breathing through device, the device feels the pressure drop and will increase/decrease the resistance, device adjusted to how patient inhales medications. Used for research purposes (insulin)
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Describe features of modern nebulisers which are metered dose liquid inhalers
Very small device. Slowly produces mist (mechanical generation of mist). Patient twists device, spring goes down, puts pressure on generating particle mist. Mist produced slowly but small distribution. E.g. Respirmat SoftMist
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Why were there many side effects of Spiriva (tiotropium bromide)
Very small particles produced, led to greater deposition in the lungs (improvement - adjust dose). Sometimes difficult to explain the use of a lower dose with this device. Different devices produce different distributions (adjust dose/same effect)
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What is required during clinical trials when testing a device? (1)
A specific formulation and device must be tested together. If the formulation is changed, then the clinical trials will have to start again with both the formulation and device (for all devices, cannot change combinations)
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What is required during clinical trials when testing a device? (2)
Different devices give different deposition profiles. Depends on the wanted deposition profile (wanted certain amount of drug into the lungs)
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What are the requirements for liquid solutions used in nebulisers? (1)
Sterile (no contamination). Isotonic (concentration is the same, ensure conc. gradient, use NaCl saline solution 0.154 M). Stable over shelf-life (test stability). Within physiological pH range of 5-8 (pH affects solubility of compounds)
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What are the requirements for liquid solutions used in nebulisers? (2)
(use of limited excipients/surfactants/concentrations, don't want to disturb equilibrium of surfactant in lungs). Free from particulates. Most products on market
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What are the requirements for liquid suspensions used in nebulisers?
Sterile, isotonic, stable over shelf-life, within physiological pH range, particle size must be within respirable range (3-5 microns). E.g. Pulmicort Respules. Suspensions not as common as solutions for nebulisers
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What are the advantages of nebulisers in general?
No formulation requirements (drug solutions, saline, surfactants). High aerolisation efficiency. High deposition efficiency. Can be used for all ages
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What are the disadvantages of nebulisers in general?
Most are not portable. Solution shelf-life and storage time is shorter (temperature affects stability). Expensive (more suitable for CF patients). Energy source required
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What is a vaporiser?
Nicotine in solution/solid particles. Press button. Voltage control. Rapid increase in temperature. Vaporisation process. Solid to gas (sublimation). Solution to gas (boiling). Heat solution to create vapour. Condensation (small droplets inhaled)
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What is in the liquid cartridge? (1)
Nicotine solution, PEG, aroma additive (not tested for safety). High concentration of PEG (not safe, more deposition of PEG in lungs, no long term studies which show effects of PEG in lungs)
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What is in the liquid cartridge? (2)
Don't know effect of compounds by temperature increase (degradation). PE - recommend NRT to patients rather than e-cigarettes (more clinical studies for NRT, on market)
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Other cards in this set

Card 2

Front

Describe the devices used in 1790s

Back

Bulky devices used, made pots (for chemistry instruments). Large jar (heat sensitive), nasal (inhalation), shape/bulkiness didn't change, fragile

Card 3

Front

Describe the devices used in 1930s

Back

Preview of the front of card 3

Card 4

Front

What are the two types of nebulisers?

Back

Preview of the front of card 4

Card 5

Front

How does the jet nebulisation work? (1)

Back

Preview of the front of card 5
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