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The DeVilbiss AutoAdjust LT nasal CPAP
system, model #8054, offers automatic
adjustment of the administered CPAP
pressure.The device is equipped with a
pneumotachometer which monitors the
patient's air flow signal for purposes of
identifying any flow restrictions and snor-
ing episodes often associated with respira-
tory events.The DeVilbiss AutoAdjust LT
nasal CPAP device has been designed to
minimize these flow restrictions which
often lead to patient arousal and fragment-
ed sleep by automatically increasing the
CPAP pressure in the presence of respira-
tory events. A proprietary pressure
adjustment control algorithm has been
developed by Sunrise Medical which
is based around event density and
event type.
The pressure profile changes are gradual
so as to prevent arousals of sleep architec-
ture, but are timely to respond to respira-
tory events requiring pressure adjust-
ments.The device also reduces airway
pressure in an attempt to minimize the
average supplied pressure administered
throughout the night. Refer to Diagram 1
of a typical pressure profile administered
to a patient and associated operating
states.
UPPER PRESSURE LIMIT
LOWER PRESSURE LIMIT
A B C
D
A)
Power switch turned on.
A-B) AutoAdjust is in low pressure pause state, providing low level of flow and CPAP pressure.
B)
Patient breathing is detected, pressure is increased to the lower pressure limit prescription setting.
C-D) Patient falls asleep.
D-E) Patient begins to have respiratory events. Unit senses the events and adjusts pressure.
E-F) Pressure returns to the lower limit as events become less frequent. (Note: pressure cannot be less than the lower
pressure limit unless the A/D button is pressed to reach the low pressure pause mode.)
F-G) Respiratory events resume and the CPAP pressure is automatically adjusted to reduce the number of events.
G)
Patient presses the A/D button on the front of the unit, causing the pressure to drop to low pressure pause level.The
low pressure pause mode of operation provides a low level of flow and pressure (approximately 3 cm H 2 O). If the
patient wakes up with a high CPAP pressure, this allows the patient to fall back asleep more comfortably.
G-H) Patient falls back asleep and begins to have respiratory evens.The AutoAdjust unit detects the events and automatically
adjusts the CPAP pressure level.
H)
CPAP pressure has been automatically increased and has reached the upper pressure limit prescription setting for the
product. (Note: CPAP pressure cannot go over the upper limit regardless of patient events.)
I)
A large leak in the system, usually at the patient mask, has been detected by the AutoAdjust CPAP and the unit has
reduced the pressure to the low pressure pause level.
J-K) Breathing signals have been sensed at the mask and normal operation of the unit has resumed.When breathing is
detected, the pressure is raised to 80% of the pressure level that the unit was operating at when the leak was sensed.
K)
The patient has awakened and has pressed the A/D button on the front of the unit to reduce the pressure to the low
pressure pause level.
L)
The patient switches the unit off.
9
G
E
F
H
TIME
DIAGRAM 1
80%
I
J
K
L
ResMed Inc. Exhibit 1029
Page 9 of 24
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