Aerosol is providing a treatment via inhalation. It provide treatment locally with better actions and less side effect.

1. Aerosol Therapy for Mechanically
Ventilated Patients
Done By : Bashaier A. Alyami

2. : Introduction
Inhaled therapy has been routinely employed for over half a
century in ambulatory patients with respiratory disorders. In
contrast, many barriers were previously thought to
preclude effective aerosol delivery in mechanically
ventilated patients.
The major barriers were :
1- the poor efficiency of aerosol-generating devices in
ventilator circuits,
2- inadequate understanding of the factors influencing
aerosol delivery during mechanical ventilation
3- mechanical ventilators that were not designed to
optimize aerosol use.

3. Characteristics of Aerosol particles :
1. Particle size
2. Inertial Impaction
3. Gravitational Sedimentation
4. Diffusion


4. : Devices used

- Nebulizers :
Nebulizer performance varies with diluent volume,
gas flow, density, operating pressure, and nebulizer
model.
During mechanical ventilation, nebulizers producing
aerosols with MMADs of 1–3 µm are more likely
to achieve deposition in the lower respiratory tract since
larger particles impact on the ventilator circuit and
endotracheal tube.

5. A common jet nebulizer system. An extrinsic gas flow, either from a compressed air
source or from the ventilator passes through a Venturi and is accelerated leading to a
pressure gradient that
causes diluent/solubilized drug in the reservoir to be aerosolized and then entrained in
.another stream of gas (tidal volume) going to the patient

6. A common ultrasonic nebulizer system . Ultrasonic waves of 1 MHz are
applied to a reservoir of drug and diluent perturbing the liquid, leading to
aerosolization and entrainment by the tidal Volume going to the patient.

7. . Cont

- Metered Dose Inhaler :
The MDI canister contains a pressurized mixture of
propellants, surfactants, preservatives, and flavoring
agents, with ;1% of the total contents being active drug.
The velocity of the liquid spray leaving the MDI is ;15 m/s,
falling by 50% within 0.1 s as a cloud develops and moves
away from the actuator orifice.

9. Factors influencing lower respiratory tract
: deposition of aerosol
* Ventilator/circuit-related factors
Ventilator settings
1. Inspiratory flow rate
2. Respiratory rate
3. Tidal volume
4. Flow waveform
5. Ventilator cycling-volume vs pressure
6. Delivery by manual bag inflations

10. . Cont
* Circuit determinants
1. Characteristics of the delivery device
a. Nebulizer
1. Volume of fill
2. Frequency selection for ultrasonic devices
3. Specifications of the nebulizer device used,
including
MMAD
4. Flow rates for jet nebulization

11. . Cont
b. MDI
1. Timing of the actuation
2. Spacer device
3. Actuator
4. Intra-ETT catheters

12. . Cont
2. Amount of drug administered
3. Humidification of inspired gases
4. Where in circuit MDI/nebulizer is
administered
5. Length and diameter of ventilator tubing
6. Diameter and length of the ETT
7. Use of low-density gas (heliox)

13. . Cont
* Patient-determined factors :
Airway determinants
1. Bronchoconstriction
2. Secretions
3. Mucosal function
Patient's effects on gas flow
1. Spontaneous respiratory pattern
2. Generation of intrinsic PEEP

14. Differences during MV :
1- Breath Configurations
During controlled mechanical ventilation (CMV),
the pattern and rate of inspiratory gas flow, as
well as the rate and pattern of breathing, may
differ from that during spontaneous
respiration.

15. : The Airway- 2
The conduit between the aerosol device and the
lower respiratory tract in mechanically
ventilated patients is narrower than the
oropharynx and has abrupt angles (eg, the 90degree connector often used to connect the
ventilator circuit wye to the ETT), which
result in points of impaction and turbulence
that are not found in the normal airway.

16. . Cont
While the ETT is narrower than the trachea, its
smooth interior surface may create a more
laminar-flow path than the structures of the
glottis and be less of a barrier to aerosol
delivery than the ventilator circuit.

17. The Environment- 3
Humidity has been shown to relate to an
increase in particle size and reduced
deposition during CMV, but no data exist to
suggest that this reduction is unique to the
ventilated patient.

18. : The Assessment- 4
The common method to assess patient response to
bronchodilator administration is through changes in
expiratory flow rates.
Most investigators have relied on changes in the inspiratory
airway resistance to quantitate a bronchodilator effect
in mechanically ventilated patients.

19. : Aerosol Generating Devices
Nebulizers : Alternatively, the air flow generated by a ventilator
can be used to power the nebulizer during inspiration
(intermittent operation). A separate line provides driving pressure
and gas flow from the ventilator to a nebulizer connected in the
ventilator circuit.
However, the driving pressure provided by most ventilators to the
nebulizer (<15 psi) is much lower than that provided by
compressed air or oxygen sources commonly available in the
hospital (≥ 50 psi).

20. Position and Method of Connecting the
: Aerosol Generator in the Ventilator Circuit
Placement of a nebulizer at a distance of 30 cm from
the endotracheal tube is more efficient than
placement between the patient Y and the
endotracheal tube because the ventilator tubing acts
as a spacer for the aerosol to accumulate between
inspirations.
Addition of a spacer between the nebulizer and the
endotracheal tube further modestly increases aerosol
delivery.

21. . Cont
Metered Dose Inhaler :
Both in vitro and in vivo studies have found that the
combination of an MDI and a chamber device results
in a four- to- six-fold greater delivery of aerosol than
MDI actuation into a connector attached directly to
the endotracheal tube or into an in-line device that
lacks a chamber.

23. Collapsible spacer chamber
Non-collapsible spacer chamber

24. : Aerosol Particle Size
Deposition in the lower respiratory tract of
mechanically ventilated patients is likely to be
more efficient with devices that generate
aerosols with a MMAD of 1–3 µm.

25. . Cont
Endotracheal Tube :
Smaller the size of ETT, greater the particle
impaction (esp in pediatric ETT)

26. . Cont
Heating and Humidity of inhaled gas :
- Greater aerosol deposition in the ventilator circuit
and ETT with heated and humidified gas
- Both diminishes pulmonary deposition of aerosols
~40% .

28. Density of the Inhaled Gas :
Inhalation of a less dense gas (ie, helium-oxygen
[heliox]), decreases the turbulence associated with
high inspiratory flow rates during mechanical
ventilation.
Preliminary reports indicate up to 50% increase in
deposition of albuterol from an MDI during CMV of a
simulated adult patient when breathing heliox
compared to that while breathing air or oxygen.

29. : Ventilator settings and Modes
For efficient aerosol delivery to the lower respiratory
tract, the V T of the ventilator-delivered breath must
be larger than the volume of the ventilator tubing and
endotracheal tube.
V T of ≥ 500 mL in adults are associated with adequate
aerosol delivery (see Table 1), 19,25 but the higher
pressures required to deliver a larger V T can be
detrimental to the lungs.

30. Actuation of an MDI into a cylindrical spacer
synchronized with inspiration resulted in ~
30% greater efficiency of aerosol delivery
compared actuation during expiration.
- Albuterol deposition was up to 23% higher in
vitro during simulated spontaneous breaths
(continuous positive airway pressure) than
with controlled breaths of equivalent V T .

31. : Administration of the Aerosol Therapy

33. : Facing disadvantages
Nebulizers :
1. Contamination and VAP


Use of aerosol was one of the
independent factor associated with
VAP
Need to be cleaned and disinfected
to minimize the risk

34. 2.
Difficulty triggering



In patient on PS mode, a –ve airway
pressure must be generated before the
ventilator deliver a breath
A continuous-flow nebulizer between the
patient and the sensor in the ventilator
makes it more difficult for the patient to
generate the –ve pressure
May lead to under-ventilation of the
patients

35. 3.
Damage to expiratory transducer

In some ventilator brand only
3.
Variable rate and particle size (depends
on the brand)
4.
Operational efficiency of nebulizer
changes with the pressure of the driving
gas and with different fill volumes

36. 6.
FiO2 change
7.
Increase tidal volume and/ or airway
pressure
8.
Cost
 Time consuming (prepare the drug,
disinfection…).
 Purchasing the aerosol generating device.

37. : Advantages of MDIs
 Decreased
cost
 Reliability of dosing
 Ease of administration
 Less
personnel time
 Freedom
 The
from contamination
ventilator circuit need not be
disconnected
 Reduce VAP

38. Options of inhaled drug delivery
during NIPPV
 Remove
patient from ventilator and
administer drug by nebulizer or MDI
 Administer nebulizer therapy inline with
NIPPV
 Administer MDI therapy inline with
NIPPV

40. A 42-year-old intravenous drug user was transferred to the
ward for noninvasive respiratory support after discharge
from the intensive care unit, where she had been treated for
. fungal pneumonia and septicemia

41. : Bronchodilator use
 Based
on the finding that aerosol
deposition is lower in MV patients than in
non-intubated patients
 higher
 So,
dose of BD were recommended
what is the precise dosing
regimen ?

42. In general, significant BD effects occur
after administration of
4 puffs albuterol with a MDI+spacer
2.5mg of albuterol with a standard
nebulizer
Potential side effects were increased if
administrated higher doses

43.  Duration
of action (e.g. Ventolin)
 Ambulatory
patients: 4-6hrs
 Mechanical ventilated: 2-4hrs vs 4-6hrs
 Ventilated
patients need more
frequent administration of BD (shortacting)
 E.g.
every 3-4 hrs

44. Thank you 