1. Aerosol Bronchodilator Therapy

2. Aerosol Is a suspension of solid or liquid particles in gas
Used to deliver bland water solutions to the respiratory tract or to administer drugs to lungs, throat, or nose
Aim to is to deliver therapeutic dose of the selected agent to the desired site of action with minimal side effects and greater efficacy and safety

3. Characteristics of Aerosol
Aerosol output
Particle size
Particle deposition
Aging

4. Characteristics of Aerosol
(i) Aerosol output
Indicates the weight or mass of the aerosol particle produced by the nebuliser per min
This can be measured by collecting the aerosol that leaves the nebuliser on filters, and measuring either the weight or the quantity of the drug

5. (ii) Particle size (Ranges from 0.5 - 3.0 micrometre)
Depends on substance being nebulised, the nebuliser chosen, the method used to deliver the aerosol, and environmental conditions surrounding the particle
Only way to determine the particle size is by laboratory measurement. Two common laboratory methods are
cascade impaction
laser diffraction
Cascade impaction
The particle size is measured in terms of Mass Median Aerosol Diameter (MMAD)
Laser diffraction
Particle size is measured in terms of Volume Median Diameter (VMD)
These two terms give particle size in terms of micrometres

6. Characteristics cont. (iii) Particle deposition
Aerosol particles are deposited when they leave the suspension in gas
There are two forms of aerosol deposition
Inhaled dose – Only a portion of aerosol is inhaled
Respirable dose – A smaller fraction of fine particles is deposited in the lungs
The mass of drug deposition is of two types
* Inhaled mass – The inhaled amount of drug
* Respirable mass – The proportion of the drug of proper size reaching the lower respiratory tract

7. Factors Affecting Penetration and Deposition
Inertial impaction
Gravimetric sedimentation
Diffusion

8. Inertial Impaction
Occurs when suspended particles in motion colloid with and are deposited on a surface
This occurs in particle size larger than 5 micrometres
Larger particles have greater inertia, which keeps them moving in straight line. When they pass through the airway they cannot make directional changes, so they easily deposit.

9. Gravimetric Sedimentation
This occurs when a particle settles out of suspension and/or is deposited due to gravity
The greater the mass, the faster it settles
This occurs in particles ranging from 1 to 5 micrometres
Breath-holding after inhalation of the aerosol increases the residence time of the particle in the lung and increases sedimentation

10. Brownian Diffusion
A primary mechanism through which deposition of particles less than 3 micrometres occurs
Since these particles are 0.5 micrometres in size, they have greater retention in the lungs

11. Aging
Particles constantly grow, shrink, collapse, and fall out of suspension
The process by which an aerosol suspension changes over time is called aging
Aging is inversely proportional to the size of the particle, so smaller particles grow or shrink faster than larger particles

12. Aerosol Therapy
A therapeutic administration of a drug in the form of an aerosol
Indications
Administer medication
Bronchospasm
Inflammation
Mucosal edema
Copious secretion
For mobilization of secretion
Home regimen
Physician’s order
Need to obtain sputum

13. Hazards of Aerosol Therapy
Infection
Airway reactivity
Pulmonary and systemic effects
Drug reconcentration

14. Aerosol Drug Delivery Systems
MDIs with and without spacer
Nebuliser
A device used for converting a liquid drug into a fine mist which can then be inhaled easily
Two types
Jet nebuliser
Ultrasonic nebuliser

15. Jet Nebuliser
Powered by high-pressure air or oxygen provided by a portable compressor, compressed gas cylinder, or 50 psi valve outlet
Principle – If a stream of gas is passed through a small hole, the gas creates a lower pressure as it emerges from the hole

16. Small-Volume Nebuliser
Definition – Nebulisers commonly used in hospital and home for drug administration have small medication reservoirs (<10ml)
Factors affecting SVN performance
Nebuliser design
Gas pressure
Density

17. Nebuliser Design Baffles Fill volume Residual volume
Nebuliser position

18. Gas Source (Wall, cylinder, compressor)
Pressure
Flow-through nebuliser
Gas density
The lower the density of the carrier gas, the less aerosol impaction occurs and the better the deposition in the lungs

19. Large-Volume Nebuliser
Used to deliver aerosolized drug to the lung
Can be used for continuous nebulization
Has a reservoir of more than 240ml producing aerosol of MMAD micrometres
Actual output and particle size vary with pressure and flow at which nebuliser operates
If pt. is on CBT, drug toxicity should be monitored since CBT causes drug reconcentration

20. Ultrasonic Nebuliser
A nebuliser in which an electric crystal is used to produce an aerosol
The crystal transducer converts an electrical signal into a high-frequency vibration ( MHz)
These vibrations enter the liquid above the transducer and disrupt the surface to create oscillation waves
If the frequency increases, the amplitude is strong enough that the oscillation waves form a geyser of droplets that break as fine aerosol particles
This is capable of producing higher aerosol output ( ml/min)
Particle size is inversely proportional to frequency of vibration

21. Types of USNs Large-Volume USN Small-Volume USN
Used mainly for bland aerosol therapy and sputum induction
Uses air blowers to carry the mist to the patient
Small-Volume USN
Medication is directly placed on top of the transducer, which is connected by cable to a power source. The patient’s inspiratory flow draws the aerosol from the nebuliser into the lung.

22. Nebulization Therapy
Definition – A process of dispersing a liquid (medication) into microscopic particles and delivering this liquid into the lungs as the patient inhales through the nebuliser
Purposes
To administer medication directly into the respiratory tract to induce sputum expectoration in case of sputum induction
To reduce the difficulty of bringing out the secretions
To increase VC

23. Prerequisites
Optimal volume of solutions in nebuliser chamber (2 - 4ml)
Oxygen- or air-driven device which produces a flow rate of 4 - 6lts/min
Advantages
High doses can be given
Tidal breathing is adequate for inhalation
Aerosolized drugs which cannot be administered through MDIs can be given through this
Avoids reflux coughing
Allows mixing of drugs

24. Disadvantages High doses may result in toxicity
Requires continuous supply of electricity
Expensive
Requires regular maintenance
Risk of transmission of airborne infection where cleaning is not adequate

25. Equipment
Nebuliser
Nebuliser solution (Terbutaline 10mg/ml, Ipravent 250mcg/ml)
Normal saline
Oxygen source or air-driven device
Oxygen tube
Face mask or mouthpiece

26. Procedure Wash hands Arrange equipment needed
Explain the use of nebuliser
Warn about side effects
Assemble nebuliser equipment
Add prescribed medicine and diluent
Hold the mouthpiece between lips with gentle pressure
Ask the patient to take deep breaths and exhale passively
Turn the nebuliser machine on and ensure sufficient mist is formed
Turn off when the mist stops
If a steroid is given, gargle or rinse mouth

27. Practical Points
Saline should be used as a diluent, not distilled water (Hypoosmolar solution can lead to reflex bronchospasm)
Drug delivery is effective depending on the source (Mouthpiece or face mask)
If a mask is used, it should be used as close to the face as possible since any gap reduces drug delivery significantly
Check for adequate mist production

28. In absence of mist, check for
Any leak
Obstruction of flow (Kinking of tube)
Misalignment of the nebuliser
Inadequate solution
Position of the nebuliser

29. Post-Procedure Vital signs to be checked before and after therapy
Assess for side effects like coughing and cardiac dysarrythmias
In case of sputum induction, note the amount, colour, and consistency of the expectorant

30. Cleaning After each Rx Disassemble the nebuliser completely
Rinse tubing, medication cup, mouthpiece, and mask in warm water
Shake off excess water and allow to air-dry
Avoid drying in dusty and smoky areas
After each day
Submerge the tubing, medication cup, mouthpiece, and mask in mild liquid detergent and warm water
Use a small brush to remove any sediment that is accumulated
Rinse parts thoroughly after washing
Immerse all parts in cidex
Remove and rinse under water
Air-dry all parts

31. Bronchodilators Two types Adrenergic bronchodilators
Anticholinergic bronchodilators
Bronchodilators delivered through
MDI
Nebulisers

32. Adrenergic Bronchodilators
Stimulates
Alpha receptor stimulation, which causes vasoconstriction and vasopressor effect
Beta 1 receptor stimulation causes increased HR and myocardial contractility
Beta 2 receptor stimulation, which relaxes bronchial smooth muscle, stimulating mucociliary activity

33. Sub-Groups Ultra short-acting bronchodilator
E.g. Epinephrine (1:100%) ml through neb
Shorter duration of action
Used for reducing swelling and controlling bleeding
Short-acting, non-catecholamine agents
Action is app. for hours, so they can be taken PRN or QID
Terbutaline
2.5mg through neb
Inj 1mg/ml
Tab 2.5/5mg
Salbutamol
Neb 2.5/5mg,
MDI 100mcg/puff 2 puffs PRN
DPI 200mcg/cap 1 cap PRN
Tab 2/4mg

34. Long-Acting Adrenergic Bronchodilator
Onset of action is within 20 min and peak effect is within 3 to 5 hours. Overall duration of action is 12 hours.
E.g. Salmeterol
MDI 25mcg/puff 2 puff BD
Formeterol
MDI

35. Adverse Effects of Adrenergic Bronchodilators
Common side effects
Headache, insomnia, nervousness, tremor, palpitations, and tachycardia
Specific side effects
Dizziness, nausea, hypokalemia, loss of bronchoprotection, CFC-induced bronchospasm, worsening ventilation perfusion ratio
CFC-induced bronchospasm is managed by replacing HFA propellants

36. Assessment of Bronchodilator Therapy
General assessment
Monitoring vital signs (RR, PR, breath sounds)
Correct technique
Specific
Monitor PEFR
ABG or SpO2 in acute state
K and blood glucose
If on long-term, monitor PFT
Action plan for asthma patients
Patient education
Technique of aerosol delivery
Cleaning of aerosol device

37. Anti-Cholinergic Bronchodilators
Acts by producing airway relaxation through blockage of cholinergic-induced bronchoconstriction
Indications
COPD (chronic bronchitis, emphysema), severe asthma
E.g. Ipratropium bromide
250mcg/ml neb 0.5mg
MDI 18mcg/puff 2 puffs qid

38. Mode of Action
Acts on the acetyl choline at the muscarinic receptors on the airway smooth muscle
Drugs
Ipratropium bromide MDI 18mcg/puff 2 puffs QID
SVN 0.5mg QID

39. Adverse Effects Common Occasional (MDI) SVN Cough and dry mouth
Nervousness, irritation, dizziness, headache, palpitation, rash
SVN
Pharyngitis, dyspnea, flu-like symptoms, bronchitis, URI, nausea, occasional bronchoconstriction, eye pain, urinary retention

40. Aerosol Therapy

41. Asthma Medication

42. Thank you for your patient listening