Humidification therapy

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: What is humidification Describe how airway heat and moisture exchange normally occurs. State the effect dry gases have on the respiratory tract . Describe how various types of humidifiers work . Identify the indications, contraindications, and hazards that pertain to humidification during mechanical ventilation 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)

12. 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.

13. Method of humidification - Passive humidifiers

14. 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

15. 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

16. Hydrophobic HMEs H ydrophobic membrane with small pores – increased surface area Works: open pores for water mist except large water molecule E fficient 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%)

17. H ygroscopic 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

18. 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.

19. 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)

20. Method of humidification - active humidifiers

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

22. Bubble through humidifiers (BTH) Works: inspired air – bubbled through – in cold water that in container - gets humidified F orm 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 ) N o 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

23. Bubble through humidifiers

24. 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

25. Simple reservoir Works: blows gas over the surface of the heated water Heated water - used in the mechanical ventilations R oom temperature fluid - used in non-invasive ventilator support T otal 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. S ealed the traps water to prevent contamination U sed for patient with spontaneous breathing O r with ventilator circuit such - CPAP & non-invasive ventilation

26. W ick 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

27. M embrane 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.

28. Nebulizer P roduces and disperses liquid particles in a gas stream or aerosol mist Used - produce humidification & deliver drug D rugs such as bronchodilator, mucolytic agent and decongestant S ize of the water droplet is between 0.5 to 5 µm P articles more than 5µm unable to reach the peripheral airways P articles 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 U ltrasonic nebulizers .

29. 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

30. 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 T he 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

31. Aerosol size of 1 to 10 µm a 95 % of particles produced are in optimal range P articles deposited directly in airway V ery effective for deliver bronchodilator H azards 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

32. Advantages and disadvantages of nebulizer Advantages I t can carry air that fully saturated with water vapour without heated. W e can increase the amount of the water vapour in the inhaled air. Disadvantage I t 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

33. 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

34. 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

35. 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)

36. 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 )

37. 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)

38. 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)

39. 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)

40. 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.

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

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

43. 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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