PAP Variations
CPAP stands for
Continuous Positive Airway Pressure.
There are several modifications to basic CPAP machines, including
automatic adjusting PAP machines, bilevel PAP
machines, and expiratory pressure decrease. What do all of these mean?
Automatic
adjusting PAP (also called Autoset)
means the machine varies the pressure while the PAP is being used. Standard CPAP machines do not do
this. They are set to one
pressure. The automatic PAP
machine uses brand-specific methods to identify if the pressure that is
being delivered to the patient is working or not. If the machine senses that the
pressure is too low, it will increase the pressure until it determines that
the sleep disordered breathing is under control. The machine does this throughout the
night. Why is this
beneficial? For most people it
does not make a difference.
However, some people have a variable pressure needs in different
stages of sleep or body positions, while other people have different
pressure needs on different nights.
Some people simply find this more comfortable than a single
pressure.
Bilevel machines allow your physician to set 2 different
pressures instead of just one.
An inspiratory pressure (also called IPAP,
the pressure the machine delivers when you are breathing in) and an
expiratory pressure (also called EPAP, the pressure the machine delivers
when you breathe out) are set.
What is the benefit of 2 pressures? Often when very high pressures are
needed to control the sleep apnea (over 20 cm H2O), the CPAP is not well
tolerated because people have difficulty exhaling. By setting an expiratory pressure
that is lower than the inspiratory pressure, many
people find it easier to breathe and therefore more comfortable.
An expiratory decrease
machine (also called C-flex) is similar to bilevel
PAP. With this mode, the
pressure is allowed to decrease during exhalation by a small amount. This is different from bilevel PAP, because the physician still only sets one
CPAP pressure and large differences in the pressure are not possible. This mode is more comfortable for
some people since exhalation is easier.
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