Download BENEFITS OF HEATED HUMIDIFICATION

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
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• volume 16 • number 4
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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.
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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
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[email protected]
• volume 16 • number 4