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BENEFITS OF HEATED HUMIDIFICATION By Edwin Cintron, RPSGT est. This is why the condensation builds up in The amount of humidity in the air can the inside of the tubing. This happens more make a big difference in determining whethdramatically when an air conditioner is in use. er or not the air is comfortable to breathe. The actual pressure is affected by this proFor some, dry air can make breathing very cess. Inspiratory pressure could be decreased difficult. This is of significant importance to by as much as 3.5 to 5.6 cm/H2O below the positive airway pressure (PAP) users. Some set pressure, while expiratory pressure may can not tolerate the treatment at all because be decreased by as much as 0.7 to 3.5 cm/H2O the air does not have enough humidity. The below the set pressure.6 To help prevent this addition of a humidifier can make it easier from occurring, insulate the tubing so that it to breathe the air, while temperature also apdoes not experience such an extreme change pears to have a significant effect on breathin temperature. ing comfort. To fully understand the role of EDWIN CINTRON, The actual amount of humidification needhumidity in helping to create a comfortable RPSGT ed to make the air more breathable depends sleeping environment, one must understand on the person. For some, a lower humidity level of 20 to 30 what humidity is and how it works. percent is sufficient, while others require a much higher Humidity can be defined as the amount of water vapor level of 50 to 60 percent.7 Dryness in the nasal passages in the air.1 This is also referred to as “relative humidity.” leads to symptoms such as sneezing, nasal congestion, upTemperature plays a crucial role in affecting how much 2 per airway infection and epistaxis (i.e., bloody nose).8 For water the air is able to hold. Typically, cooler temperasome, the perceived inability to breathe nasally can be comtures are related to lower levels of humidity. This is bepletely reversed by adding a heated humidifier. Asthmatic cause the air is denser when it is cold. In contrast, at highsymptoms and seasonal allergies can be a factor as well. It er temperatures the air is able to hold more water vapor. is unknown why some people are so much more sensitive In other words, although the exact amount of water vapor to dry air than others. may be the same at warm and cool temperatures, the Although the PAP machine improves the symptoms of percentage of humidity will show a dramatic difference. sleep apnea, it does come with its fair share of problems. To illustrate this principle, let’s use 25 mg H2O/l as an From the comfort of the mask to the comfort of the acarbitrary amount of water vapor in the air. This amount tual pressure of air, some patients will completely give up of water vapor may be 100 percent humidity at colder on PAP therapy if problems are not resolved early. It is estemperatures, but only 10 percent at higher temperatures. timated that about 27 percent of people will discontinue The percentage that represents relative humidity is based their use of PAP within the first 6 months because of on the amount of water vapor in the air compared to how 3 discomfort.9 This number increases to about 40 percent much water vapor the air can potentially hold. in the first 18 months.9 This can be prevented with the The air is typically dryer during the winter months addition of heated humidification.10, 11 Many sleep laborathan it is during the summer months.4 This can create tories connect a heated humidifier to the clinical PAP unit an additional obstacle when choosing between a cool during the initial PAP titration. This may help with overall passover humidifier or a heated passover humidifier. compliance when it is addressed at the start of therapy. Typically, a heated humidifier will provide a higher Drying of the mucosal membranes is one of the major amount of humidity in the PAP tubing;5 however, room problems that sleep professionals and sleep patients need temperature also must be taken into consideration. If to address. The three major functions of the nose are to the air in the room is cold, the temperature inside of the humidify, filter and warm.12 With the initiation of PAP PAP tubing will be cold as well. This will decrease how therapy, the pressurized air will take away the nose’s ability much humidity will make it from one end of the tubing to sustain its normal functions. When this occurs, the mouth to the other. Even when using a heated humidifier at its comes open as the patient struggles to take in enough of a maximum setting, the air may be cooled before it reaches breath for proper ventilation. When a patient is unable to the patient’s PAP mask because of external temperature. breathe nasally, there are several options to consider. A full Extreme temperature differences in this case can cause face mask can be used, but the mouth is incapable of doing “rainout” (i.e., buildup of water inside of the PAP tubing). any of the nose’s three functions. As a result, breathing may Another factor to consider is condensation. To better be even more difficult.13 Even with a humidifier connected, understand how condensation occurs, take a cold beverage some patients may still complain of a dry mouth or sore out of a refrigerator. Since there is a dramatic difference in throat, and they may wake up coughing. Before considertemperature between the inside of the container and the ing a full face mask, a heated humidifier should be used outside air, the side of the container that is warmest will to determine if the nasal stuffiness is due to drying of the build up some moisture. In this experiment, the outside mucosal membranes. Not everyone will react to humidificaof the container is warmest, which causes it to capture the tion in the same way, so some patients may only need a cool invisible water vapor from the air. When PAP air is being passover humidifier while others may require a heated unit. humidified and heated, the inside of the tubing is warmContinued on page 22 A2Zzz 2007 • volume 16 • number 4 21 Continued from page 21 Since temperature plays such a crucial role in humidification with PAP treatment, it would make sense that warmer room temperatures would be best to allow a higher amount of humidity in the bedroom. This, however, may not be conducive to good sleep, as cooler temperatures seem to be favorable for the sleep environment.14 The challenge is to find a happy medium with a temperature that is cool enough to promote good sleep but warm enough to be conducive to good breathing. 5. Wiest GH, Fuchs FS, Brueckl WM et al. In vivo efficacy of heated and non-heated humidifiers during nasal continuous positive airway pressure (nCPAP)therapy for obstructive sleep apnoea. Respir Med 2000;94(4):364-368. 6. Carlson D. Benefits of heated humidification and CPAP. Sleep Rev 2003; November-December. Available at: http://www.sleepreviewmag.com/issues/articles/200311_05.asp. Accessed September 18, 2007. 7. Minnesota Blue Flame Gas Association. Humidity and the indoor environment. 2004. Available at: http://www.blueflame.org/datasheets/humidity. html. Accessed September 18, 2007. 8. Malik NW, Kenyon GS. Changes in the nasal airway mucosa and in nasal symptoms following continuous positive airway pressure (N-CPAP) for obstructive sleep apnoea. Aust J Otolaryngol 2004; June. Available at: http://findarticles.com/p/articles/mi_ qa3868/is_200406/ai_n9450137/pg_1. Accessed September 18, 2007. 9. Carskadon MA. Encyclopedia of sleep and dreaming. Macmillan; 1993. References 1. USA Today. Understanding humidity. 2007 Aug 25. Available at: http://www.usatoday.com/weather/ whumdef.htm. Accessed September 18, 2007. 2. Commonwealth of Australia - Bureau of Meteorology. Measuring humidity. 2007. Available at: http://www.bom.gov.au/lam/humiditycalc.shtml. Accessed September 18, 2007. 3. Williams, J. Getting a handle on humidity. USA Today. 2005 July 18. Available at: http://www.usatoday.com/ weather/wrelhum.htm. Accessed September 18, 2007. 4. Mayo Foundation for Medical Education and Research. Dry air: combating the effects of dry winter air. 2006 Sept 29. Available at: http://www.mayoclinic.com/ health/dry-air/GA00044. Accessed September 18, 2007. 10. Massie CA, Hart RW, Peralez K, Richards GN. Effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure. Chest 1999;116(2):403-408. 11. Malhotra A, Ayas NT, Epstein LJ. The art and science of continuous positive airway pressure therapy in obstructive sleep apnea. Curr Opin Pulm Med 2000;6(6):490-495. 12. Answers Corporation. Nose. 2007. Available at: http://www.answers.com/topic/nose?cat=health. Accessed September 18, 2007. 13. Verma M, Seto-Poon M, Wheatley JR et al. Influence of breathing route on upper airway lining liquid surface tension in humans. J Physiol 2006;574(Pt 3): 859–866. Ask For Our Full Color Catalog Today! 14. National Sleep Foundation. Sleep environment. 2007. Available at: http://www.sleepfoundation. org/site/c.huIXKjM0IxF/b.2422597/k.BA20/Sleep_ Environment.htm. Accessed September 18, 2007. Edwin Cintron, RPSGT, has 14 years of experience in sleep and is currently the Polysomnography Course Instructor at Erwin Technical Center in Tampa, Fla. Phone: 1-800-654-6266 Fax: 1-858-481-3654 www.gereonics.com 22 A2Zzz 2007 [email protected] • volume 16 • number 4