Aerosol therapy

by Dr.Vinod K Ravaliya

1. BY-Vinod Ravaliya, MPT
Dept. of Physiotherapy

2. AIM OF AEROSOL THERAPY
•To deliver a therapeutic dose of the selected
agents to the desired site of action.
•Choice of route for drug delivery
-Directly to the site of action
-Therapeutic action with side
Effects: high therapeutic index,
greater efficacy & safety

3. AEROSOL
•Definition
A suspension of very fine liquid or solid
particles in a gas.
•Key to aerosol therapy is aerosol particle
•Respirable range:1-5 micron
•80%drugs deposited in oropharynx
•10% in walls of inhaler
•10% in the lungs
( SP Newman et.al.1985 )

4. •In mechanically ventilated patients
-51%within nebulizer unit
-2.2%IN Rt LUNG &0.9% IN Lt LUNG
(SH Thomas M fiddler et.Al.1993)
•In clinical settings, medical aerosols are
generated with atomizer, nebulizer or inhalers –
devices that physically disperse matter into
small particles & suspend them into a gas.

5. AEROSOL DELIVERY SYSTEMS
The three principle types of devices widely
used are :
1.MDI-metered dose inhalers
2.DPI-dry powder inhalers
3.Nebulizers

6. METERED DOSE INHALERS
•Most widely used
•Aerosol flow rate 30
m/s or 100 km/h
•Propellants were
CFC

7. ADVANTAGES OF MDI
•Inexpensive
•Light, compact
•Quick delivery of drugs
•Precise and consistent doses

8. DISADVANTAGES OF MDI
•Difficulty in coordination of activation &
inspiration
•Time consuming to teach
•Contains CFC
•Cannot be used in children & elderly
•Cannot be used in seriously ill patients
•Cannot be used in mechanically ventilated
patients

10. SPACERS

11. SPACERS
•Holding chambers or reservoirs
•Attachment to a MDI
•Advantages :
1.No need to activate coordination
With inspiration
2.Increases drug deposition in lung
3.Reduces drug deposition in mouth
4.Used in children with face mask
5.Decreases incidence of oral
thrush

12. DRY POWDER INHALERS
•Introduced in 1960’s
•No propellants
•Requires patient’s own Inspiratory effort
to form aerosol
•Powder is delivered only when patient
inhales

13. ADVANTAGES OF DPI
•Light weight
•No hand breath coordination
•Quick delivery of drugs
•Useful in children above 5 yrs of age
Disadvantages of DPI
• Require high inspiration flow >28 l/min

14. COMPARISION BETWEEN MDI &DPI
•High velocity aerosols
•Requires coordination
•Time consuming to
teach
•Requires slow & deep
breathing only
•Aerosol velocity
depends on inspiratory
flow rate
•No coordination
needed
•Easy to teach
•Requires high insp
flow >28 l/min

15. CHARACTERISTICS OF THERAPEUTIC
AEROSOLS
•Effective use of aerosols requires an
understanding of characteristics of the
aerosols.
•Aerosol output (wt /minute)
•Emitted dose
This tells little about the amount of
drug reaching the targeted site of action.

16. •A substantial proportion of particles that leave
a nebulizer may never reach the lungs.
•Effectiveness of medical aerosols depends on
amount of aerosol particles deposition to the
lower respiratory tract & deposition of aerosol
influenced by many other factors.

17. FACTORS INFLUENCING DEPOSITION
•Physical & chemical properties of
aerosols
•Anatomy of the respiratory tract
•Physiological factors
(J E Agnew, D Pavian, S W Clarke et.al.1984)

18. PHYSICAL & CHEMICAL PROPERTIES
OF AEROSOLS
GRAVITY
• Aerosol size must be >1 microns because at this
mass gravity loses its influence on particles.
( Chantal Darquenne , G Kim Prisk et.al.2000 )
•Gravity influence is in direct relation with particle
mass
•Greater mass—tendency to undergo proximal
airway deposition

19. INERTIAL IMPACTION
Water particles
Gas molecules

20. PARTICLE SIZE
•Aerosol particle size depends upon :
-- nebulizer chosen
--Method used to generate aerosol
•It is not possible to visually determine whether a
nebulizer is producing an optimal size
particles…
•Aerosols traverse tubular strs in which turbulent
flow is the rule…
•>Particle size---- gravity influence

22. •1-5 micron MMAD important determinant of its
deposition efficacy in LRT
•1-3 micron greater deposition

23. TONICITY OF THE FLUID
•Hypertonic fluid tend to absorb water.
•Hypotonic aerosols may evaporate
•Normally, mucous membrane is neutral in
relation to electrical charges

24. ANATOMY OF THE RESPIRATORY TRACT
•Diameter
Infants and children have small diameter of an
airway suggest that having low level of drug
deposition , even that is adequate when
considered in terms of body weight (mg of
drug deposited per kg of BW ).
(Fok T F , S.Monkman , M Dolvich et.al.1996 )
•Length
•Branching angles of airway segments

25. PHYSIOLOGICAL FACTORS
•Airflow
Increasing flow 6,8,10 L / min increased the
mass output of particles in the respirable
range of 1-5 microns.
( D Hess , P Williams , S Pooler et.al. 1996 )
•Breathing pattern
Deposition of particles are directly related
to inhaled volume & inversely related to
ventilatory rate.
•Inspiratory hold

26. NEBULIZER

27. •1872 - NEBULIZER derived from the Latin
“nebula” meaning “mist”

•1874 –definition as “an instrument for converting
a liquid into a fine spray, especially for medical
purposes”
•The logic of creating a vapor or aerosol for the
inhalation treatment of lung disease is at least as
old as written records of medicine.

28. •The Ayurvedic tradition of medicine in India
which dates back perhaps 4,000 yrs or more ,
used inhaled substances for managing
respiratory disorders.
•19
th
century-inhalation devices were described
•1930-atomizers

29. •1940-collison nebulizer
It used baffle to filter out larger particles,
thus distinguishing a “nebulizer” from
“atomizer”.
•1950-wright nebulizer
Much more compact than collison, closely
resembled today’s pneumatically powered neb.
•1960-ultrasonic nebulizer
A diff method of creating liquid aerosols .

30. TYPES OF NEBULIZERS
1. Jet nebulizer
2. Ultrasonic nebulizer

31. JET NEBULIZER

33. •It is a system in which high velocity gas flow
is directed into a tube that is immersed in a
water reservoir.
•It operates from a pressurized gas
•working mechanism :
Venturi Principle : As the gas flow
through the tube, water is drawn up in
between the surfaces and come across the
way of gas flow through fine spore. this gas
stream impacts upon the fluid surface and
dispersing liquid as an aerosol.

34. FEATURES OF JET NEBULIZER
•Cools during operation
•Less expensive
•More noise
•More Rx time
•small particle size
•Small output rate

35. ULTRASONIC NEBULIZER

38. •It is an electric nebulizer
•Working principle : piezoelectric effect
ultrahigh frequency current

piezoelectric transducer

ultrahigh frequency vibrations

disk vibration
couplant (water bath)

39. FEATURES OF ULTRASONIC NEBULIZER
•More expensive
•Heats up during operation , Less noise
•Less Rx time
•Large average particle size ( Joseph L Rau
et.al.2002 )
•Large output rate
•0.5 to 3 microns – 90 % of particles within effective
range

40. INDICATIONS FOR NEBULIZER
•Useful in children ,
Handicapped person ,
Seriously ill patients
•Ventilated patients
•Elderly individuals
•High doses can be given
•Combination drugs can be given

41. •Enhancement of secretion clearance
•Sputum induction
•Humidification of respired gases
•Prevent dehydration
•Prevent or relieve bronchospasm

42. HAZARDS OF NEBULIZER
•Bronchospasm
•Over hydration
•Delivery of contaminated aerosols
•Tubing condensation
•Swelling of retained secretions

43. DRUGS FOR NEBULIZATION
•Distilled water or normal saline
•Mucolytics : mesna , acetylcysteine
•Beta 2 agonists : salbutamol , terbutalin ,
fometerol , salmeterol
•Antimuscarinic : ipratropium bromide
•Steroids : budesonide
•Antibiotics
•Antifungal

44. Distilled water/NS
•Cheapest / very economical
•Easily available
•Effective Mucolytic
•Free of ions (distilled water)
•Routinely used in practice

45. Mucolytic agents
•Mucomyst
•Drug action
•Side effects
•How to counteract

46. Beta-2 agonists
•Mechanism of action
beta receptor stimulation
adenylcyclase

IC ATP

IC cAMP
smooth muscle relaxation

47. salbutamol
•Short acting
•Selective beta 2 agonist
•Peak of action
•Long term use effects
•Side effects

48. Epinephrine
•Classic catecholamine
•Strong alpha & beta-1 beta-2 action
•Available 1:100 solution
•0.25 to 0.5 ml in 4ml NS

•Lasting effect , side effects

49. Anticholinergic agent
•Ipratropium bromide
•Site of action
•Usually given through mouthpiece

50. Nebulizer as an adjunct to chest
physiotherapy
•Nebulized NS enhances mucociliary clearance ,
given thrice in a day before chest
physiotherapy & also salbutamol before NS to
prevent bronchoconstriction
( J.Morton , J.A.Douglass , J.Reidler et.al.1996 )
•With the patient resting in an upright position;
chest physiotherapy, by the forced expiration
technique with postural drainage; and chest
physiotherapy following five minutes' inhalation
of either nebulized normal saline or nebulized
terbutaline 5 mg

51. •Use of both nebulized saline and nebulized
terbutaline immediately before chest
physiotherapy gave a significantly greater yield
of sputum than did physiotherapy alone, and
terbutaline.
(Sutton PP, Davidson J , Smith FW et.al.1988 )
•In mechanically ventilated patients , those
having low lung volume chest PNF technique
should be used to improve lung volume & thus
maximum aerosols can be administered.
•Lung segment which is to be drained out
require to positioned up so that aerosols reach
to upper area.

52. TECHNIQUE FOR USING NEBULIZER
•1. Place drug solution in nebulizer,
employing a fill volume 2-6 ml
•2. Place nebulizer in Inspiratory line
• 3. Ensure airflow of 6-8 L/min through the
nebulizer.
• 4. Ensure adequate tidal volume ( 500 ml in
adults). Attempt to use duty cycle > 0.3, if
possible.

53. •5. Observe nebulizer for adequate aerosol
generation throughout use.

•6. Disconnect nebulizer when all medication is
nebulized or when no more aerosol is being
produced.

54. CONCLUSION
•Nebulizer is the key component as a rule for
gaining chest clearance on mech.vent Pts.
•physiotherapist must give chest physiotherapy
following neb to augment secretion drainage
•Ensure proper position for nebulization.
•Choice of a nebulizer on the basis of need of
therapeutic effectiveness & availability of a
device.
•Only about <10% drug reaches to the desired
site , so try to optimize drug deposition.
• use cleaned nebulizer & prepare fresh solution.

55. •Adjust adequate oxygen flow 6-8 L/min to
produce particles in respirable range.
•Aerosol particle deposition is directly related to
inhaled volume & inversely related to
ventilatory rate , so maintain inspiration for 3-5
sec & breath holding for 2-4 sec or as long as
possible.
•Determine the therapeutic effectiveness
following nebulization + chest physiotherapy.