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HUMIDIFICATION BY: MELODY H. MANALO BSRT :)
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Transcript of HUMIDIFICATION BY: MELODY H. MANALO BSRT :)
HUMIDIFICATION DURING INVASIVE AND
NON INVASIVE MECHANICAL VENTILATION
Objectives
1. To understand humidification.2. To 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.
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.
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
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
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.
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.
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.
Method of humidification -
PASSIVE HUMIDIFIERS
Advantages of Using Passive Humidifiers DuringMechanical Ventilation
Heat and moisture exchange (HME) Known as ‘Swedish nose’ Light weight disposal device Used with mechanical ventilator or breathing
spontaneously Similar to nasopharynx It function without the additon of a water source or
electricity. 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,
hydrophobic and hygroscopic
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
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%)
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
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.
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)
Method of humidification -
ACTIVE HUMIDIFIERS
Systemic hydration
Increase the amount of fluid intake orally or intravenous
To keep our body from dehydratedTo avoid air way secretion become more
tenacious
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
Bubble through humidifiers
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
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
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
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.
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.
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
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
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 hydrationsHypothermiatransition of infectwheezing or bronchospasmbronchoconstriction when artificial
airway is usededema of the airway wall
Contraindications: bronchoconstriction's and history of hyperresponsiveness
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
Indications, contraindications, complications of aerosal therapy
According to AARC clinical practice guideline, 1992Indications:• Presence of upper airway edema—cool, bland aerosol• Postoperative management of the upper airway• Need for sputum specimens or mobilization of secretionsContraindications:• Bronchoconstriction• History of airway hyperresponsivenessComplications:• Wheezing or bronchospasm• Bronchoconstriction when artificial airway is used• Infection• Overhydration• Patient discomfort
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)
• 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)
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)
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.
Assessment of Outcome
• Humidification is assumed to be appropriate if, on regular, careful inspection, the patient exhibits none of the listed hazards or complications.
Common problems of humidification
• Cross contamination• Condensation• Proper conditioning of inspired gas• Enviromental safety• Overhydration• Bronchospasm• Noise
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.
Reference• Pryor, J., & Ammani Prasad, S. (1998). Physiotherapy for respiratory and cardiac problems (2nd ed.).
Edinburgh: Churchill Livingstone.• Fink J. (2010). Humidity and aerosol therapy. Cairo J, Pilbeam S, editors; Mosby’s respiratory equipment, 8 ed• Hess, D., MacIntyre, N., & Mishoe, S. (2012). Respiratory care (1st ed., p. Dean R. Hess, Neil R. MacIntyre,
Shelley C. Mishoe, William). Sudbury, Mass.: Jones & Bartlett Learning.• Kacmarek, R., Stoller, J., Heuer, A., & Egan, D. (2013). Egan's fundamentals of respiratory care (1st ed.). St.
Louis, Mo.: Elsevier/Mosby.• American Association for Respiratory Care: Clinical practice guideline: humidification during mechanical
ventilation. Respir Care 37:887, 1992.• Boots, R., George, N., Faoagali, J., Druery, J., Dean, K., & Heller, R. (2006). Double-heater-wire circuits and
heat-and-moisture exchangers and the risk of ventilator-associated pneumonia. Critical Care Medicine, 34(3), 687--693.
• Cairo, J., & Pilbeam, S. (2010). Mosby’s respiratory care equipment (8th ed.). Mosby.: St. Louis.• Campbell, E., Baker, M., & Crites-Silver, P. (1988). Subjective effects of humidification of oxygen for delivery
by nasal cannula. A prospective study. CHEST Journal, 93(2), 289--293.• Chatburn, R., & Primiano Jr, F. (1987). A rational basis for humidity therapy. Respiratory Care, 32, 249.• Djedaini, K., Billiard, M., Mier, L., Le Bourdelles, G., Brun, P., & Markowicz, P. et al. (1995). Changing heat and
moisture exchangers every 48 hours rather than 24 hours does not affect their efficacy and the incidence of nosocomial pneumonia. American Journal Of Respiratory And Critical Care Medicine,152(5), 1562--1569.
• Hinds, C., & Watson, D. (1996). Intensive care (2nd ed., pp. 33-175). london: Saunders.• Tilling, S., & Hayes, B. (1967). Heat and moisture exchangers in artificial venniation. British Journal Of
Anaesthesia, 59, 1181-4188.• Rch.org.au,. (2014). Clinical Guidelines (Nursing) : Oxygen delivery. Retrieved 23 April 2014, from
http://www.rch.org.au/rchcpg/hospital_clinical_guideline_index/Oxygen_delivery/#Del_Mode
THANK YOU BY: MELODY H. MANALO BSRT