1. Humidification Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA, Dip. Software statistics PhD (physio) Mahatma Gandhi medical college and research institute, puducherry – India

2. Definition Humidity is a measure of the amount of water vapour in a gas. Absolute humidity is defined as actual mass of water vapour present in a known volume of gas. 34 mg / l to 45 mg / l Upper airway to alveolus

3. Relative humidity Relative humidity is defined as the ratio of the mass of water vapour in a given volume of gas to the maximum amount of water vapour that the same gas can hold at the same temperature. Relative humidity is expressed as a percentage.

4. Yes - humidification humidification maintains mucosal integrity, ciliary activity, prevents the drying of secretions and helps in easy expulsion of respiratory secretions when coughing. (e.g. ventilating a patient with dry gas through a tracheal or tracheostomy tube) can result in cracking of mucosa, drying of secretions, keratinisation of the tracheo-bronchial tree, reduction in ciliary activity, atelectasis and infection No

5. Clinical signs Dry nonproductive cough Dyspnoea Substernal pain Thick secretions

6. Over-humidification It can result in water intoxication, especially in neonates and infants in intensive care, water clogging and airway burns

7. Normal airway humidification While nose breathing at rest, inspired gases become heated to 36°C and are about 80% to 90% saturated with water vapour. Mouth breathing reduces this to 60% to 70%

9. Aims of humidity therapy Gas at nose/mouth 50% RH with 10 mg/litre --- 22 deg. Gas at hypopharynx 95 % RH with 34 mg/l --- 29 degree Mid trachea 100 % with 40 mg/l. 31 – 35 deg.

10. Sources CO2 absorbent Exhaled gases Rinsing the tubes

11. Measure humidity Hair hygrometer This is based on the principle that the length of hair increases with increasing humidity It is fairly accurate between 30 and 90%. Wet and dry bulb hygrometer Two mercury thermometers, one in ambient temperature and the other in contact with water through a wick are used. Rate of evaporation prop. Humidity

12. Measure humidity Regnault’s hygrometer Mass spectrometer principle of reduction in the ultraviolet light transmitted through the medium containing water vapour

13. Types of humidifiers Low flow Less than the inspiratory needs Bubble Simple diffuser High flow Inspiratory needs are met HME, wick type

14. Bubble humidifier

15. Bubble diffuser humidifiers

16. Picture of bubble- diffuser

17. Function Gas comes from DISS Capillary tube Exits as small bubbles Pick up water vapour and come out Diffuser – smaller bubbles, greater surface area and better humidification

18. Factors Flow of gas Water level Ambient temperature 5 l/ min- AH is 10 - 20 mg/l, RH is 40 % at 37 deg.

19. Disadvantages Transport water borne microbes High gas flows an aerosol is created and microbes can be transferred High flows --- delivery tube kinked – high pressure develops – PRV( pressure relief valve) – alarm at 2 PSI can be set.

20. High flow humidifiers HME Heat moisture exchangers Disposable devices that trap some exhaled water and heat, and deliver them to patient on subsequent inhalation (minimize water and heat loss) Disposable devices that trap some exhaled water and heat, and deliver them to patient on subsequent inhalation (minimize water and heat loss) combined with a filter for bacteria and viruses  Heat and Moisture Exchanging Filter (HMEF) combined with a filter for bacteria and viruses  Heat and Moisture Exchanging Filter (HMEF)

21. Swedish nose First – aluminium

24. Most modern HMEs are of 2 types: Most modern HMEs are of 2 types: a. Hydrophobic (not much used) a. Hydrophobic (not much used) b. Hygroscopic b. Hygroscopic

25. Hydrophobic HMEs – 1.Hydrophobic membrane with small pores, pleated to increase surface area 2.Allow passage of water vapor but not liquid water at usual ventilatory pressures 3.Efficient bacterial and viral filters 4.Performance may be impaired by high ambient temperatures

26. Hygroscopic HMEs – 1.Wool, foam or paper like material coated with moisture-retaining chemicals 2.Medium may be impregnated with a bactericide When wet – performance is poor

27. Minimum standard Its not 20 – 20 cricket Its 30 – 30 cricket Minimum 30 mg/ litre at 30 deg. c

28. Advantages 1.Inexpensive 2.Easy to use 3.Small, lightweight, simple in design 4.Silent in operation 5.Do not require water/ external energy source/ temperature monitor/ alarms 6.No danger of overhydration/ hyperthermia/ burns/ electrical shock

29. Disadvantages 1.Can deliver only limited humidity 2.Insignificant contribution to temperature preservation 3.Less effective than active humidifiers, specially after intubation lasting for several days 4.Increased dead space  may necessitate increase in tidal volume  increased work of breathing

30. If you are in continuous search of an ideal one ???

32. Can We use HME here ?? Preexisting pulmonary disease with copious secretions Bloody secretions Expired tidal volume is less than 70 % of the delivered tidal volume ( if there is no other problem) Be cautious

33. Heated humidifier

34. HEATED HUMIDIFIERS Incorporate a device to warm water in the humidifier, some also heat inspiratory tube Incorporate a device to warm water in the humidifier, some also heat inspiratory tube Humidification chamber Humidification chamber Heat source Heat source Temperature monitor Temperature monitor Thermostat Thermostat Controls Controls Alarms Alarms

37. Use In circle system, heated humidifier is placed in the inspiratory limb downstream of unidirectional valve by using an accessory breathing tube In circle system, heated humidifier is placed in the inspiratory limb downstream of unidirectional valve by using an accessory breathing tube Must not be placed in the expiratory limb Must not be placed in the expiratory limb Filter, if used, must be placed upstream of humidifier to prevent it from becoming clogged Filter, if used, must be placed upstream of humidifier to prevent it from becoming clogged In Mapleson systems, humidifier is usually placed in fresh gas supply tube In Mapleson systems, humidifier is usually placed in fresh gas supply tube

39. Clinical tips Humidifier must be lower than patient Condensate must be drained periodically Delivery tube should not rest on other surfaces or be covered with sheets Beware alarms are set for temperature – not for humidity

40. Advantages 1.Capable of delivering saturated gas at body temperature or above, even with high flow rates 2.More effective humidification than an HME

41. Disadvantages Water spillage into the breathing circuit and even into tracheobronchial tree. A water trap will help reduce this problem. Airway burns due to thermostat failure and overheating. Colonization of water with harmful bacteria can occur. This may be reduced by heating the water to 60°C.

42. How was the progress Hot water bath –(upto 50 deg)-- water condensate because there was difference in temperature between the humidifier and the patient end. Then a heated wire was introduced in the inspiratory system – then also in the expiratory tubes. The flow transducers in the ventilators confused with water vapour to confuse readings and hence at the expiration there was a heating element to get the gas to 37. deg

43. Types of humidifiers Low flow Less than the inspiratory needs Bubble Simple diffuser High flow Inspiratory needs are met HME, vapor phase, wick type

44. One more classification Passive HME they do not filter respiratory gases Active - they do not filter respiratory gases Heated and unheated Nebulizers

45. Wick on the sides of the bottle WICK

46. Aerosol therapy – different topic

48. MUCOLYTICS Agents capable of dissolving, digesting or liquefying mucus Agents capable of dissolving, digesting or liquefying mucus N-acetylcysteine (NAC) N-acetylcysteine (NAC) Mesna Mesna Sodium bicarbonate Sodium bicarbonate Dornase alpha (Pulmozyme) Dornase alpha (Pulmozyme)

49. Act by 1.Weakening of intermolecular forces binding adjacent glycoprotein chains – Disruption of Disulfide Bonds (NAC, Mesna) 2.Alteration of pH to weaken sugar side chains of glycoproteins (Soda bicarb.) 3.Destruction of protein (Proteolysis) contained in the glycoprotein core – Breaking down of DNA in mucus (Dornase alpha

50. N-acetylcysteine (NAC) Sulfhydryl - containing tripeptide Sulfhydryl - containing tripeptide Better known as the antidote for acetaminophen overdose Better known as the antidote for acetaminophen overdose Primarily a mucolytic agent that acts by disrupting the disulfide bridges between mucoprotein strands in sputum Primarily a mucolytic agent that acts by disrupting the disulfide bridges between mucoprotein strands in sputum

51. NAC

52. NAC (contd.) liquid preparation (10 or 20% solution) that can be given as an aerosol spray, or injected directly into the airways liquid preparation (10 or 20% solution) that can be given as an aerosol spray, or injected directly into the airways Aerosolized NAC -- avoided when possible provoke coughing and bronchospasm Aerosolized NAC -- avoided when possible provoke coughing and bronchospasm Direct instillation of NAC into the tracheal tube is preferred, especially when there is an obstruction Direct instillation of NAC into the tracheal tube is preferred, especially when there is an obstruction Daily use of NAC is not advised because the drug solution is hypertonic (even with the saline additive) and can provoke bronchorrhea Daily use of NAC is not advised because the drug solution is hypertonic (even with the saline additive) and can provoke bronchorrhea

53. Summary Humidity – definition, types Normal – physiological – Indications Types two classifications HME and F Bubble, diffuser, heated, nebulizers

54. Thank you all