1Nebulizers and Humidifiers

Hospitals

Nebulizers and humidifiers

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Dutch Workingparty Infection PreventionPublished: August 2003

Changed: December 2003Revision: August 2008

Table of ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.1 Nebulisation . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.2 Humidification . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Nebulisation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.1 Ultrasonic nebulisation. . . . . . . . . . . . . . . . . . . . . . . 42.2 Jet nebulisation . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Infection risk involved in nebulisation . . . . . . . . . . . . . . . . . 74 Working safely during nebulisation . . . . . . . . . . . . . . . . . . 74.1 Nebulisation equipment in general . . . . . . . . . . . . . . . . . . 74.2 Large-volume nebulisation equipment . . . . . . . . . . . . . . . . . 84.3 Low-volume nebulisation equipment . . . . . . . . . . . . . . . . . 84.4 Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 Cleaning and disinfection of nebulisers . . . . . . . . . . . . . . . . . 95.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95.2 Home situation . . . . . . . . . . . . . . . . . . . . . . . . . . 95.3 Hospital situation . . . . . . . . . . . . . . . . . . . . . . . . . 96 Humidification. . . . . . . . . . . . . . . . . . . . . . . . . . 106.1 Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Infection risks involved in humidification . . . . . . . . . . . . . . . 108 Working safely during humidification . . . . . . . . . . . . . . . . 118.1 Disposable humidification devices . . . . . . . . . . . . . . . . . 118.2 Non-disposable humidification devices . . . . . . . . . . . . . . . 119 Cleaning, disinfection and sterilisation of humidifiers . . . . . . . . . . 11Appendix A References. . . . . . . . . . . . . . . . . . . . . . . 13

2 Nebulizers and humidifiers

IntroductionThis guideline describes measures to prevent infections when using nebulisa-tion and humidification equipment. On the one hand, respiratory tract infec-tions can develop in patients when microorganisms in the aerosols producedby nebulisation are inhaled. On the other hand, patients can become infectedby coming into contact with contaminated parts of the equipment. The chanceof infection can be reduced by applying clear guidelines on safely handlingand cleaning, disinfecting and/or sterilising the equipment.

In hospitals, the nebulisation and humidification equipment addressed in thisguideline are mainly used in children’s wards, departments of ear, nose andthroat diseases, intensive care units, and departments of respiratory diseases.The equipment is also used in nursing homes and in home situations.

This guideline does not cover systems for nebulisation or humidificationwhich are components of ventilation equipment or anaesthesia equipment,including the Heat Moisture Exchanger.

Nebulisers used to make it possible to inhale drugs in powder form are notaddressed in this guideline, nor are the occupational hygiene aspects of thenebulisation of drugs and other substances.

This guideline has been structured around the type of equipment. The usermay encounter two different areas of application:

- administration of medication, for which small-volume nebulisers areused,

- air humidification, with a preference for disposable systems prefilledwith sterile water.

Manufacturers of the nebulisation or humidification equipment are required toprovide written instructions on the purpose, the mode of use and the methodof cleaning, disinfection and sterilisation of the equipment [1]. If chemicaldisinfection is required, the manufacturer must also provide information aboutthe disinfectant to be used [2]. The manufacturer should also indicate howoften a procedure for cleaning and disinfection, and if necessary sterilisation,can be carried out without affecting the quality of the equipment. The para-graphs Cleaning, disinfection and sterilisation, for both nebulisation andhumidification equipment respectively, describe the conditions for cleaning,disinfection and sterilisation so that they can be used as a basis for the asses-sment of whether the manufacturer’s instructions meet the requirements.

Nebulizers and humidifiers 3

1 Definitions

1.1 Nebulisation

Nebulisation is when a liquid - water or dissolved drug - is added to the air ora gas (mixture) in the form of small droplets. The result is a mist or aerosol.The droplet size determines the extent to which the mist can penetrate the air-ways. Droplets smaller than 5µm have the potential to penetrate the alveoli.Larger droplets will not get any further than the trachea and the bronchi.There are different types of nebulisers, which are summarised in Table 1.

1.2 Humidification

Humidification means the liquid (in practice this is only water) is provided asa vapour, i.e. in its gaseous form. The purpose of humidification is to makethe air to be inhaled as humid as possible. The equipment is subdivided intodisposable and non-disposable devices.

There are three types of humidifier on the market:

a. Bubble diffusion (the most important type)

b. Passover (available in heated and unheated models)

c. Blow-by

2 Nebulisation

2.1 Ultrasonic nebulisation

Ultrasonic nebulisation works by means of an electrically generated high-fre-quency vibration in a crystal, as a result of which the liquid to be nebulisedmoves so much that extremely small droplets can escape from the liquid andremain suspended as a mist above the surface of the liquid.

Table 1: Broad outline of types of nebulisers

Type of nebuliser Purpose

Large volume ultrasonic nebuliser humidification, sometimes administra-tion of drugs

Small volume ultrasonic nebuliser administration of drugs

Jet nebuliser (nearly always small volume)

administration of drugs


Ultrasonic nebulisers can contain disposable parts, such as a water bottle,tubes, medicine cups or mouthpieces. Figure 1 shows a diagram of an ultraso-nic nebuliser.

Figure 1, Ultrasonic nebuliser. A high frequency source and a piezo electric crystalare used to transfer high-frequency vibrations to a liquid, which combines with theinflowing air to create a mist that ends up in the air inhaled by the patient.

2.1.1 Ultrasonic nebulisation with coupling fluid

In this ultrasonic nebulisation equipment the crystal’s vibrations are usuallytransferred by means of water, called coupling fluid, to a plastic receptaclecontaining the liquid to be nebulised.

The level of the sterile liquid to be nebulised can be maintained automaticallyfrom a bottle or bag.

2.1.2 Ultrasonic nebulisation without coupling fluid

These are devices through which the water or drug solution to be nebulisedcome into direct contact with the coated crystal.

� The use of this type of equipment is currently discouraged.


The ultrasonic nebulisers without coupling fluid currently available (endof 2002) cannot be properly cleaned and disinfected, and we thereforeadvise against using them at this time.

2.1.3 Large-volume ultrasonic nebuliser

As a rule, the purpose of large-volume nebulisers is to humidify the inhaledair. However, they are sometimes also used to administer drugs to the respira-tory tract.

A small fan blows the mist, with either oxygen or compressed air that has pas-sed through a dust filter, into the mouthpiece from where the patient caninhale the mist.

2.1.4 Small-volume ultrasonic nebuliser

Small-volume ultrasonic nebulisers are used to administer drugs to the respi-ratory tract.

The patient inhales the mist himself/herself through the mouthpiece. Howe-ver, sometimes the mist is blown into the mouthpiece by a fan. The pressurecreated by the fan is lower than the pressure of the air exhaled by the patient.

2.2 Jet nebulisation

With jet nebulisers, capillary action leads the liquid (with the dissolved drug)through the channels around the air channel, whereby droplets of differentsizes are formed above the liquid by the impulse transmission with the flow ofair and are transported along with the air. The droplets that are too large arecollected by a droplet collector and sent back to the liquid reservoir. The pres-sure of the air in the system created by the compressor is always higher thanthe exhaled air. As a result no (potentially contaminated) air can be blownback into the liquid reservoir or medicine cup. However, saliva can flow backafter use, as a result of which the reservoir can become contaminated. Figure2 shows a diagram of a jet nebuliser.


Figure 2, Jet nebuliser. Taken from Pharm World Sc 2000;22:75-81. Droplets are released bymeans of compressed air. Fine droplets are inhaled when the patient breathes in through themouthpiece [3].

3 Infection risk involved in nebulisationIf measures for cleaning, disinfection or sterilisation of nebulisation equip-ment are not observed properly, the equipment may become contaminatedwith pathogenic microorganisms [4-11]. Bacteria may be demonstrated in themist produced by the contaminated equipment [5, 7]. Nebulisers have beendescribed as the source of some infections with Burkholderia cepacia, Pseu-domonas aeruginosa and Legionella spp [6, 12-21].

4 Working safely during nebulisation

4.1 Nebulisation equipment in general

� The receptacle should not be filled until immediately before use.


� The receptacle containing the liquid to be nebulised may never be refil-led.

� The receptacle should be cleaned every 24 hours.

When using a prefilled, sterile, disposable system, the parts may be useduntil the system is empty. In general this takes no longer than two days.

� If the equipment is fitted with dust and bacteria filters, these should bereplaced as instructed by the manufacturer.

� The coupling fluid in an ultrasonic nebuliser with coupling fluid must bechanged each time the nebuliser is cleaned.

4.2 Large-volume nebulisation equipment

� Large-volume nebulisation equipment is patient-specific (may not beused on other patients).

4.3 Low-volume nebulisation equipment

� All parts that come into contact with the patient’s breath, including themask, the mouthpiece, connecting pieces and medicine cups, are patient-specific and are disposed of as waste following the therapy period. A disposable tube should be used.

4.4 Liquids

� The water or 0.9% natriumchloride used to dissolve drugs must be ste-rile and should preferably come from a package for single use.

Due to the small volume of liquid, an ampoule should preferably be usedto guarantee sterility. If a needle and syringe are used to extract waterfrom the ampoule, they may only be used once.

Tap water is not sterile and therefore may not be used [9, 16-19].

� Bottles of sterile liquid may not be used more than 24 hours after ope-ning. The date and time at which the package is opened must thereforebe noted on the package. The liquid must be stored in the refrigerator.

� Drugs must be sterile and should come from packages for single usewhenever possible.

� When using multi-dose bottles, the maximum storage temperature andthe storage conditions indicated must be observed. The date on whichthe seal is first punctured must be noted on the package.


5 Cleaning and disinfection of nebulisers

5.1 General

The purpose of cleaning the equipment is to:

- ensure that the equipment’s functionality is maintained

- prepare the equipment for disinfection.

The purpose of disinfecting and sterilising the equipment is to:

- prevent the transfer of microorganisms.

� Non-sterile gloves should be worn during the procedure.

� Cleaning and disinfection should be followed by drying.

� Parts should be constructed in such a way that effective cleaning, disin-fection and drying are possible.

The possibility of drying is particularly important.

5.2 Home situation

� To make sure that the equipment keeps functioning properly, in thehome situation it must be rinsed with lukewarm water after each use,then cleaned with washing-up liquid (dishwashing liquid), rinsed withwarm water and dried thoroughly afterwards.

Whether or not to use soapy water depends on the drug applied. Drugresidue may negatively affect the equipment’s functioning.

The manufacturer must indicate the right drying method, particularlywith regard to the hollow areas in which no moisture is allowed toremain.

� The equipment should be cleaned, disinfected with 70% alcohol and airdried daily.

5.3 Hospital situation

� In a hospital situation the nebulisers must also be rinsed with lukewarmwater after each use and then cleaned, disinfected with 70% alcohol andair dried, or handled using an alternative method as instructed by themanufacturer. The procedure must include the steps of washing, disin-fection and drying.

� When used by the same patient, the mask, mouthpiece and connectingpieces must be cleaned, disinfected with 70% alcohol and air dried daily.

� The disposable tubes of the nebuliser must be replaced daily.


6 Humidification

6.1 Technique

Humidification can be achieved using heated or unheated humidificationequipment.

Humidification devices can be distinguished by volume. Small-volume devi-ces are usually unheated whereas large-volume devices usually do heat theflow of air.

There are a number of different types of humidification equipment on themarket, which use different methods of humidification.

6.1.1 Disposable humidifiers

6.1.1.1 Bubble Diffusion

In Bubble-diffusion humidifiers the gas is led beneath the water level bubblesas it rises. A simple example is the bubble bottle under an oxygen flow meter.Another familiar example is the cascade humidifier, used in combination withventilation equipment.

6.1.2 Non-disposable humidifiers

6.1.2.1 Passover and Blow-by humidifiers

Passover and Blow-by humidifiers are unheated humidifiers in which the gasis led over a large water surface. An example of a simple passover system isthe radiator tray.

� In view of the high risk of contamination through these humidifiers they

may not be used in hospitals.

7 Infection risks involved in humidification

Humidification involves the distribution of water in the gaseous phase ratherthan droplets or other particles on which bacteria could be spread. Thereforethere is no risk of the gas mixture contaminating the lungs through humidifi-cation.

However, direct contact with contaminated water or liquid reservoirs can con-stitute another route of infection for the user of the equipment as well as thestaff. Many types of microorganisms can contaminate the humidificationequipment. The degree of contamination depends partly on the temperature ofthe water, the presence of any nutrients and the duration of use.


8 Working safely during humidification

8.1 Disposable humidification devices

Disposable systems prefilled with sterile pyrogen water can remain in useuntil the water has been used up and may be used on several patients.

� The tube must be replaced after each patient.

8.2 Non-disposable humidification devices

The use of non-disposable humidification equipment is discouraged. Shouldits use nevertheless be required, the following rules apply.

� The water used for humidification must be sterile. Tap water is not ste-rile and therefore may not be used.

� Bottles of sterile water may not be used more than 24 hours after ope-ning. The date and time at which bottles are opened must be noted on thebottle.

When using disposable ready-to-use water systems, they can remain inuse until the water is used up.

� When using infusion systems and infusion bags to supply water forlong-term humidification, the infusion system must be replaced at thesame time as the infusion bag.

� When using multi-dose bottles, the maximum storage temperature andthe storage conditions indicated must be observed.

9 Cleaning, disinfection and sterilisation of humidifiers

9.0.1 Disposable humidifiers

� A new tube must be used for each patient.

Besides that, disposable humidifiers require no further cleaning or disin-fection.

9.0.2 Non-disposable humidifiers

When purchasing the equipment, it is advisable to verify how often a proce-dure for cleaning and disinfection, and if necessary sterilisation, can be car-ried out without affecting the quality of the equipment. The manufacturer isrequired to provide the necessary information on this.

� The equipment should always be cleaned after use.

If the equipment is used several times a day but for the same patient,daily disinfection in addition to cleaning is sufficient.


� If the equipment is used for more than one patient, it must be cleanedand sterilised after each use.

� Non-sterile gloves should be worn during the procedure. The glovesshould be removed after the procedure and the hands washed or rubbedwith hand alcohol.

The outside of the equipment can also become contaminated.

� The parts of non-disposable systems, such as liquid reservoirs, immer-sion tubes and diffuser grid must be given a daily general householdcleaning without detergent and then autoclaved and stored in a dry anddust-free place.

� If the material cannot withstand regular sterilisation, the use of disposa-ble systems is preferred.


Appendix A References1. Gemeenschappen, E., Medische hulpmiddelen. Publicatieblad v.d. Euro-

pese Gemeenschappen, 1993. Richtlijn 93/42 EEG van de RaadISSN 0378-7087(14 juni).

2. W.I.P., Desinfectie en sterilisatie. Richtlijn nr. 3b, 2002.

3. Le Brun, P.P.H., et al., A review of the technical aspects of drug nebuli-zation. Pharm World Sc, 2000. 22: p. 75-81.

4. Vassal, S., R. Taamma, and N. Marty, Microbiologic contaminationstudy of nebulizers after aerosol therapy in patints with cystic fibrosis.AJIC, 2000. 28: p. 347-51.

5. Parlevliet, G.A., H.H.M. Meester, and J.G.M. Koeleman, Contaminatievan de ultrasone vernevelaar DV-99. THIP, 1996. 1: p. 11-16.

6. Burdge, D.R., E.M. Nakielna, and M.A. Noble, Case-Control and VectorStudies of Nosocomial Acquisition of Pseudomonas Cepacia in AdultPatients with Cystic Fibrosis. Inf Contr and Hosp Epidemiol., 1993. 3:p. 127-130.

7. Bergsma, W., Inhalatie-therapie. THIP, 1990. 5: p. 135-138.

8. Chatburn, R.L., R.R.T. Marvin D Lough, and J.D. Klinger, An In-Hospi-tal Evaluation of the Sonic Mist Ultrasonic Room Humidifier. Respira-tory Care, 1984. 29(9): p. 893-899.

9. Zuravleff, J.J., et al., Legionella pneumophila Contamination of a Hos-pital Humidifier. Am Rev Respir Dis, 1983. 128: p. 657-661.

10. Hamill, R.J., E.D. Houston, and P.R. Georghiou, An Outbreak of Burk-holderia (Formerly Pseudomonas) cepacia. Respiratory Tract Coloniza-tion and Infection Associated with Nebulized Albuterol Therapy. AnnIntern Med, 1995. 122: p. 762-766.

11. Ramsey, A.H., P. Skonieczny, and D.T. Coolidge, Burkholderia cepacialower respiratory tract infection associated with exposure to a respira-tory therapist. Inf Contr Hosp Epidemiol., 2001. 22(7): p. 423-426.

12. Reboli, A.C., R. Koshinski, and K. Arias, An Outbreak of Burkholderiacepacia Lower Respiratory Tract Infection Associated with Contamina-ted Albuterol Nebulization Solution. Inf Contr Hosp Epidemiol, 1996.17: p. 741-743.

13. Cobben, N.A.M., M. Drent, and M. Jonkers, Outbreak of severe Pseu-domonas aeruginosa respiratory infections due to contaminated nebuli-zers. J of Hosp Infect., 1996. 33: p. 63-70.


14. Yamagishi, Y., J. Fujita, and K. Takigawa, Clinical Features of Pseu-domonas cepacia Pneumonia in an Epidemic Among Immunocompromi-sed Patients. Chest, 1993. 103: p. 1706-1709.

15. Takigawa, K., J. Fujita, and K. Negayama, Nosocomial Outbreak ofPseudomonas cepacia Respiratory Infection in ImmunocompromisedPatients Associated with Contaminated Nebulizer Devices. Kansensho-gaku Zasshi, 1993. 67(11): p. 1115-25.

16. Mastro, T.D., B.S. Fields, and R.F. Breiman, Nosocomial Legionnaires'Disease and Use of Medication Nebulizers. The Journal of Inf Diseases,1991. 163: p. 667-671.

17. Woo, A.H., A. Goetz, and V.L. Yu, Transmission of Legionella by Respi-ratory Equipment and Aerosol Generating Devices. Chest, 1992. 102: p.1586-90.

18. Kaan, M.J.A., A.M. Simoons-Smit, and D.M. MacLaren, Anothersource of aerosol causing nosocomial legionnaires' disease. Journal ofInfection, 1985. 11: p. 145-148.

19. Arnow, P.M., T. Chou, and D. Weil, Nosocomial Legionnaires' DiseaseCaused by Aerosolized Tap Water from Respiratory Devices. The Jour-nal of Inf Diseases, 1982. 146(4): p. 460-467.

20. Moffet, H.L. and D. Allan, Colonization of Infants Exposed to Bacte-rially Contaminated Mists. Amer J Dis Child, 1967. 114: p. 21-25.

21. Joly, J.R., P. Déry, and L. Gauvreau, Legionnaires' disease caused byLegionella dumoffii in distilled water. CMAJ, 1986. 135: p. 1274-1277.


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