use of humidification.

1. Humidification
Mr.Thirumalaya
(PTH5201)
JOHN MATTHEWS
I12000166
James Patrick Ong Weng Yew
I12001672

2. Objectives
• At the end of the lesson, students will be able to:
1. What is humidification
2. Describe how airway heat and moisture exchange
normally occurs.
3. State the effect dry gases have on the respiratory tract.
4. Describe how various types of humidifiers work.
5. Identify the indications, contraindications, and hazards
that pertain to humidification during mechanical
ventilation
6. State how to select the appropriate therapy to condition a
patient’s inspired gas.

3. Introduction
• Humidification is a method to artificially
condition the gas used in respiration of a
patient as a therapeutically modality.
• Active method is by adding heat or water or
both to the device or passive which is
recycling heat and humidity which is exhaled
by the patient.

4. Indications of Humidification
• Primary:
• Overcoming humidity deficit created when
upper airway is bypassed
• To humidify dry medical gases
• Secondary:
• To manage hypothermia
• To treat bronchospasm caused by cold air

5. Clinical signs and symptoms of
inadequate humidification
• 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

6. Physiology
• 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.

7. Physiology cont
• 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.

8. Physiology cont
• Mucociliary elevator contains cilia and
associated fluid. Mucociliary cell contain 95%
water 5% of DNA, lipid, carbohydrate and
glycoprotein.
• When the temperature at 37˚, absolute
humidity at 44mg/l, relative humidity of 100%
is an ideal condition for the cilia to work
efficiently

9. • As inspired gas moves into the lungs, it achieves
BTPS conditions (body temperature, 37° C;
barometric pressure; saturated with water vapor
[100% relative humidity at 37° C])
• This point, normally approximately 5 cm below
the carina, is called the isothermic saturation
boundary (ISB).
• Above the ISB, temperature and humidity
decrease during inspiration and increase during
exhalation.
• Below the ISB, temperature and relative humidity
remain constant (BTPS).

10. • The ISB shifts distally when a person breathes
through the mouth rather than the nose; when
the person breathes cold, dry air; when the upper
airway is bypassed (breathing through an artificial
tracheal airway); or when the minute ventilation
is higher than normal.
• When this shift of ISB occurs, additional surfaces
of the airway are recruited to meet the heat and
humidity requirements of the lung.
• These shifts of the ISB can compromise the
body’s normal heat and moisture exchange
mechanisms, and humidity therapy is indicated.

11. Taken from Fink J. (2010)

13. Principles of humidifier function
• 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 – There is greater opportunity for
evaporation to occur, the longer a gas remains in
contact with water.
• Thermal mass – The higher the mass of water or core
element of a humidifier, the higher its capacity to
transfer or hold heat.

14. PASSIVE
HUMIDIFIERS

15. Heat and moisture exchange (HME)
Known as ‘Swedish nose’
Light weight disposal device
Used with mechanical ventilator or
breathing spontaneously
Similar to nasopharynx
Works: exhales gas moisture & heat
recollected in condenser humidifier
return back in inhale gas to lung
With a filter for bacteria and viruses it
become Heat and Moisture Exchanging
Filter (HMEF)
Types of HMEs: simple condenser
humidifiers, hydrophobic and hygroscopic

16.  simple condenser humidifiers
 high thermal conductivity -
metallic gauze, corrugated
metal or parallel metal tubes
 Works: breath in air cools
condenser breath out
the condenser will warm and
humidified
 Trap approximately 50%
exhale moisture

17.  Hydrophobic HMEs
 Hydrophobic membrane with small pores
– increased surface area
 Works: open pores for water mist except
large water molecule
 Efficient in filter bacterial and viral
 Expiration condenser temperature to
25˚C
 Inspiration condenser temperature to
10 ˚C
 The efficiency almost same as the
hygroscopic(70%)

18.  Hygroscopic HMEs
 Material – low thermal conductivity
 paper, wool or even wool
 Paper coated with lithium chloride or calcium – to recollect
the moisture
 Works: exhaled: some vapor will condense and the rest will
absorbed by hygroscopic salt
 Inspiration: the low water pressure in the inspired air cause
released the water molecule direct from hygroscopic salt
 high efficiency compare to hydrophobic HMEs
 approximately 70% efficiency that is 40 mg/l on exhaled, 27
mg/L on return

20. According to International Organization for
Standardization (ISO) ideal HME should operate at 70%
efficiency or better providing at least 30 mg/L water
vapor.
Advantage:
 inexpensive
 easy to use
 Small and lightweight
 silent in operations
 do not required water, temperature monitor, alarms
 No burns, no danger of over hydrations and electric
shock.

21. Disadvantages:
 less effective than active humidifiers
 can deliver only limited humidity
 increased in death space (Boots et al 2006)
 Increased tidal volume and work of breathing
 Need change the HME every 24(Boots et al 1993)
or 48(Djedaini et al 1995)

22. ACTIVE
HUMIDIFIERS

23. Systemic hydration
Increase the amount of fluid intake orally or
intravenous
To keep our body from dehydrated
To avoid air way secretion become more
tenacious

24. Bubble through humidifiers (BTH)
 Works: inspired air – bubbled through – in cold
water that in container - gets humidified
 Form or mashed diffusers - produce small
bubbles - total surface area to contact with
water
 It have pressure relived valve – open when
pressure is more than 2 psi - creates visible and
audible alarm
 used with facemask or canula that supplied O²
 Settings: gas temperature 10˚C, relative
humidity 100% and absolute humidity 9.4 mg/l
(St.Louis 1994, mosby)
 No objective benefit(BTH + nasal canule)
according to (camplebell et al 1988) but
subjective report shows benefit
 prevent water condense in tube that block the
oxygen transfer

25. Bubble through humidifiers

26. Passover humidifiers
Works: blow gas over heated sterile
water - gas absorbs the water
vapour - inhaled by patient
Temperature 32˚C-36˚C, water
content 33-43g/m³(Hinds & Watson)
3 type of passover humidifiers:
 simple reservoir type
 wick type
 membrane type

27.  Simple reservoir
 Works: blows gas over the surface of the heated
water
 Heated water - used in the mechanical
ventilations
 Room temperature fluid - used in non-invasive
ventilator support
 Total surface of contact area between the gas
and water is very less
 Humidifier placed below the patient airway
level to prevent overflow of the airway by the
condenser water.
 Sealed the traps water to prevent
contamination
 Used for patient with spontaneous breathing
 Or with ventilator circuit such - CPAP & non-
invasive ventilation

28. Wick humidifier
 have an absorbent material -
increase the total surface area of
dry air to interference with
heated water
 wick is placed upright position in
the water
 Works: dry gas move in chamber
- flows around the wick - absorb
the heat and moisture - gas
saturated with water vapour
leave the chamber
 No bubbling - no aerosol

29. Membrane type humidifiers
 separate the fluid from the gas
stream – use hydrophobic
membrane
 So only water vapour can pass
through the membrane not water
 No bubbling - no aerosol
 Advantage of Passover humidifiers
compare to bubble humidifiers
 it can maintain saturation at
high flows rate
 they add little or no resistance
to spontaneous breathing
circuits
 minimal risk for spreading
infections.

33. Nebulizer
 Produces and disperses liquid particles in a gas stream or
aerosol mist
 Used - produce humidification & deliver drug
 Drugs such as bronchodilator, mucolytic agent and
decongestant
 Size of the water droplet is between 0.5 to 5µm
 Particles more than 5µm unable to reach the peripheral
airways
 Particles less 0.5µm is very light, and will come back with
expired gases without being deposited in airways
 2 types of nebulizer
 Large Volume Jet Nebulizers
 Ultrasonic nebulizers.

34. Large Volume Jet Nebulizers
 Works: by forced a jet of
high-pressure gas into a
liquid - inducing shearing
forces - breaking the water
up into fine water particles
 produces particles of size 5
to 30 µm
 only 30 to 40% of particles
produced are in optimal
range
 Most of the particles get
deposited in wall of main
airways

35.  Ultrasonic nebulizer
 used piezoeeletric crystal - contract
and expend and produce radio
wave – due to electric current.
 Works:
 Crystal transducer converts: radio
waves into high-frequency
mechanical vibrations
 vibration is transmitted to the
water surface
 The high mechanical energy
creates cavitation in the fluid
 it formed a standing wave which
will disperses liquid particles
 When inhaled it will enter
respiratory tract
 Frequency of oscillation
determines the size of the water
particles

36.  Aerosol size of 1 to 10 µm a
 95% of particles produced are in optimal
range
 Particles deposited directly in airway
 Very effective for deliver bronchodilator
 Hazards from nebulizer:
cause over hydrations
Hypothermia
transition of infect
wheezing or bronchospasm
bronchoconstriction when artificial
airway is used
edema of the airway wall
 Contraindications: bronchoconstriction's
and history of hyperresponsiveness

37. Advantages and disadvantages of
nebulizer
Advantages
• It can carry air that fully saturated with water vapour
without heated.
• We can increase the amount of the water vapour in the
inhaled air.
Disadvantage
• It is very expensive.
• The pneumatic nebulizer needs high air flow to operate.
• The ultrasonic nebulizer need electric supply to operate
thus it may cause electric shock

38. Indications, contraindications, complications of
aerosal therapy
According to AARC clinical practice guideline, 1992
Indications:
• Presence of upper airway edema—cool, bland aerosol
• Postoperative management of the upper airway
• Need for sputum specimens or mobilization of secretions
Contraindications:
• Bronchoconstriction
• History of airway hyperresponsiveness
Complications:
• Wheezing or bronchospasm
• Bronchoconstriction when artificial airway is used
• Infection
• Overhydration
• Patient discomfort

39. Indications according to AARC
• Humidification of inspired gas during mechanical
ventilation is mandatory when an endotracheal
or a tracheostomy tube is present.
• Primary:
• Humidifying dry medical gas
• Overcoming humidity deficit created when upper
airway is bypassed
• Secondary:
• Managing hypothermia
• Treating bronchospasm caused by cold air

40. Contraindications according to AARC
• There are no contraindications to providing
physiologic conditioning of inspired gas during
mechanical ventilation. However, an HME is
contraindicated in the following circumstances:
• For patients with thick, copious, or bloody
secretions
• For patients with an expired tidal volume less
than 70% of the delivered tidal volume (e.g.,
patients with large bronchopleural fistulas or
incompetent or absent endotracheal tube cuffs)

41. Contraindications cont
• For patients whose body temperature is less
than 32° C
• For patients with high spontaneous minute
volumes (>10 L/min)
• For patients receiving in-line aerosol drug
treatments (an HME must be removed from
the patient circuit during treatments)

42. Hazards of humidification during
mechanical ventilation according to
AARC Clinical practice Guideline
• Hazards and complications associated with the use of
heated humidifier (HH) and HME devices during
mechanical ventilation include the following:
• High flow rates during disconnect may aerosolize
contaminated condensate (HH)
• Underhydration and mucous impaction (HME or HH)
• Increased work of breathing (HME or HH)
• Hypoventilation caused by increased dead space (HME)
• Elevated airway pressures caused by condensation (HH)

43. • Ineffective low-pressure alarm during
disconnection (HME)
• Patient-ventilator dyssynchrony and improper
ventilator function caused by condensation in the
circuit (HH)
• Hypoventilation or gas trapping caused by
mucous plugging (HME or HH)
• Hypothermia (HME or HH)
• Potential for burns to caregivers from hot metal
(HH)

44. Hazards cont
• Potential electrical shock (HH)
• Airway burns or tubing meltdown if heated wire
circuits are covered or incompatible with
humidifier (HH)
• Possible increased resistive work of breathing
caused by mucous plugging (HME or HH)
• Inadvertent overfilling resulting in unintended
tracheal lavage (HH)
• Inadvertent tracheal lavage from pooled
condensate in circuit (HH)

45. Assessment of need
• Either an HME or an HH can be used to
condition inspired gases:
• HMEs are better suited for short-term use
(≤96 hours) and during transport.
• HHs should be used for patients requiring
long-term mechanical ventilation (>96 hours)
or for patients for whom HME use is
contraindicated.

46. Assessment of Outcome
• Humidification is assumed to be appropriate
if, on regular, careful inspection, the patient
exhibits none of the listed hazards or
complications.

47. Common problems of humidification
• Cross contamination
• Condensation
• Proper conditioning of inspired gas
• Enviromental safety
• Overhydration
• Bronchospasm
• Noise

49. Conclusion
• Humidification is a means using a device to
condition the air delivered to the respiratory
airways. This therapy is particularly useful for
patients who are mechanically ventilated or have
impaired respiratory tracts. Humidification can
assist clearance of secretions when clearance
mechanism is not effective or when upper
airways bypassed by endotracheal tube.
• The main goal of humidification therapy is to
maintain normal physiologic conditions in lower
airways.

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