oxygen therapy

2.  Humidification is a method to artificially
condition the gas used in respiration of a
patient as a therapeutic modality.
 Active method is by adding heat or water or
both to the device.
 Passive method is recycling heat and
humidity which is exhaled by the patient.

3.  Primary : Overcoming humidity deficit
(upper airway bypass)
 To humidify dry medical gasses
 Secondary: To manage hypothermia
 To treat bronchospasm (due to cold air)

4.  Dry and non-productive cough
 Atelectasis
 Increased airway resistance
 Increased work of breathing
 Increased incidence of infection
 Thick and dehydrated secretions
 Complaints of substernal pain and airway
dryness

5.  Heat and moisture exchange is a primary function
of the upper respiratory tract, mainly the nose.
 The nasal mucosal lining is kept moist by
secretions from mucous glands, goblet cells,
transudation of fluid through cell walls, and
condensation of exhaled humidity.
 As the inspired air enters the nose, it warms
(convection) and picks up water vapor from the
moist mucosal lining (evaporation), cooling the
mucosal surface.

6.  Condensation occurs on the mucosal
surfaces during exhalation, and water is
reabsorbed by the mucus (rehydration).
 The mouth is less effective at heat and
moisture exchange than the nose because of
the low ratio of gas volume to moist and
warm surface area and the less vascular
squamous epithelium lining the oropharynx
and hypopharynx.

7.  Temperature – As the temperature of a gas increases, its
ability to hold water vapour (capacity) increases and vice
versa.
 Surface area – There is more opportunity for evaporation to
occur with greater surface area of contact between water
and gas.
 Time of contact – Longer a gas remains in contact with
water, greater is the opportunity for evaporation.
 Thermal mass – Higher the mass of water or core element
of a humidifier, higher is its capacity to transfer or hold heat.

8.  Heat & moisture exchange
 Large volume jet nebulizers
 Ultrasonic humidifier
 Bubble through humidification
 Passover humidifier

9.  Light weight disposal device
 Used with mechanical ventilator or breathing
spontaneously
 Similar to nasopharynx
 It collects and conserves the patient’s expired
moisture and heat. With a filter for bacteria and
viruses it become Heat and Moisture Exchanging
Filter (HMEF)
 Types of HMEs: simple condenser humidifiers
Hygroscopic HME & Active HME

10. Simple condenser
humidifier
Hygroscopic heat
moisture exchanger
Active heat moisture
exchanger
• Contains condenser
element to trap heat and
humidity of expired gas
• Retains about 50% of
expired heat and
humidity
• Maximum absolute
humidity is 18 to 28 mg/L
•Uses condenser
element made of paper,
wool, or foam
•Material includes a salt(
calcium chloride)
• Maximum absolute
humidity is 22 to 34 mg/L
•Add heat or humidity (or
both) to inspired gas
•External heat and
moisture is introduced
into inspired gas
•Capable of providing
100% relative humidity.

11. Hydrophobic HME
 Hydrophobic membrane with small
pores
 Membrane is pleated to increase the
surface area
 Provides moderately good inspired
humidity
 May be impaired by high ambient
temperatures
 Efficient bacterial and viral filters
 Allow the passage of water vapor but
not liquid water at usual ventilatory
pressure
 Associated with small increases in
resistance even when wet
Hygroscopic HME
 Contain a wool/foam/paper like
material coated with moisture-
retaining chemicals
 Medium may be impregnated with a
bactericide
 Composite hygroscopic HMEs – a
hygroscopic layer plus a layer of thin,
nonwoven fiber membrane that has
been subjected to an electrical field to
increase its polarity -- improves
filtration efficiency and
hydrophobicity.
 Composite hygroscopic HMEs are
more efficient than hydrophobic ones
.
 Lose their airborne filtration
efficiency if they become wet
 Their resistance can increase greatly
when wet

12. Type Hygroscopic Hydrophobic
Heat and moisture exchanging efficiency Excellent Good
Effect of increased tidal volume on heat
and moisture exchange
Slight decrease Significant
decrease
Filtration efficiency when dry Good Excellent
Filtration efficiency when wet Poor Excellent
Resistance when dry Low Low
Resistance when wet Significantly
increased
Slightly
increased
Effect of nebulized medications greatly
increased
Little effect

13.  Gas passes through tube
to bottom of water
reservoir
 Gas bubbles rise up in
the reservoir
 Provides humidity for
oxygen therapy

14.  Directs gas over liquid or over
surface saturated by liquid
 Types:
 Simple reservoir model
 Wick units
 Membrane devices
 Simple reservoir : Gas flows
over surface of volume of water
.Usually used as heated system
to provide humidity to
mechanically ventilated patients

15.  Inhalation of cold mist or water may cause
bronchoconstriction in patients with hyper
reactive airways.
 Water reservoirs – good culture medium for
bacteria – increase risk of infection

16.  Nebulization is the method of administering drugs by
inhalation.
 Liquid Nebulisation is a common method of medical
aerosol generation.
 A nebuliser is a device that converts liquid into aerosol
droplets (fine mist) suitable for inhalation.
 Nebulisers use oxygen, compressed air or ultrasonic
power to break up medication solutions and deliver a
therapeutic dose of Aerosol particles directly to the
lungs.

17.  Delivery of bronchodilator drugs : Status
asthmaticus
 Administration of antibiotics and anti
antifungal agents: cystic fibrosis .
 To aid expectoration :Bronchial secretions
 Local analgesia: alveolar carcinoma.

18.  Patients with unstable and increased blood
pressure
 Individuals with cardiac irritability (may
result to dysrhythmias)
 Persons with tachycardia
 Unconscious patients (therapeutic effect may
be significantly low)

19.  Drug availability varies with different types of
nebulizers.
 Cools inspired air , risk of bronchospasm
 Bacterial contamination
 Patient adherence may be hindered
 Patient becomes over dependent

20.  A minimum residual volume(< 0.5 ml).
 Aerosol delivered only during inhalation.
 No waste aerosol should be released to the environment.
 Small and portable.
 Aerosol delivered with a droplet size distribution suitable
for pulmonary deposition.
 Rapid treatment time, quite and unobtrusive in use.
 Monitor patient compliance.

21. mass median aerodynamic
diameter
 ≤ 1μm : Reach up to the
alveoli
 0.5-5μm: Beyond the
10th generation of
bronchi (respirable
particles)
 ≥ 5 μm : Oropharynx

22.  Solution or suspensions can be nebulized by
ultrasonics or an air jet and administered via
a mouthpiece, ventilation mask or
tracheostomy.
 Types of nebulizers :
 Jet nebulizer
 Ultrasonic wave nebulizer
 Vibrating mesh Nebulizers

23.  Compressed air is forced
through an orifice, an area of
low pressure is formed where
the air jet exits.
 A liquid may be withdrawn
from a perpendicular nozzle
(the Bernoulli effect) to mix
with the air jet to form
droplets.
 Carrier gas (oxygen) can be
used to generate the “air jet”.

24.  Less portable than inhalers
 Delivery may take 5 to 10 mins or longer.
 Require power sources, maintenance,
cleaning.
 Bulky
 Noisy

25.  Continuous gas flow to neb chamber
combined with patients inspired air.
 Exhaled air does not mix with aerosol,
amount of solution wasted is minimized.

26. ADVANTAGES DISADVANTAGES
High output ,short treatments. Cannot be used in ventilator circuits.
Higher dose than T- Neb is possible. Not cost effective for short term use.
Multiple one –way valve reduce
waste.
Not readily adaptable to tracheostomy
masks
Cost effective for long - term

27.  Ultrasound waves are formed in an
ultrasonic nebulizer chamber by a ceramic
piezoelectric crystal that vibrates when
electrically excited.
 These set up high-energy waves in the
solution, within the device chamber ,of a
precise frequency that generates an aerosol
cloud at the solution surface.

29.  Mesh/membrane with 1000-7000
laser drilled holes vibrates on top
of the liquid reservoir, and
thereby pressures out a mist of
very fine droplets through the
holes.
 More efficient than ultrasonic
neb.
 The high nebulization capacity
(>0.25 ml/min) device offers short
inhalation time.

31. Advantages :
 Small hand-held devices
 Very short administration time(typically 1-2
breaths)
 Highly efficient, precise aerosol delivery
 Breath control to ensure reliable drug
delivery to lung
 Simple to use.

32.  Nebulizers are designed primarily for use
with aqueous solution or suspension.
 Drug suspension use primary particles in the
range of 2-5 microns.
 Nebulizer solutions are usually formulated in
water, although other cosolvents (Glycerin,
propylene glycol, ethanol) may be used.

33.  Nebulized aerosol is introduced to the patient by
compressed air from a device known as positive pressure
ventilator.
 A mouthpiece may be inserted in the mouth may be
attached tightly to the face.
 A face tent fits more loosely around the patients
mouth,allowing speech.
 A tracheostomy mask may be fitted to the patients
tracheostomy tube directly and require T shaped adapter.