Who, What, Why, and When
Gary Hamilton, BS, RRT
Clinical Specialist
ResMed
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
Employed by ResMed
Own stock options of ResMed
By the end of this session, you should be able to:

Identify when a CPAP may not be the device of
choice

Recognize different uses of bilevel and the
different disease states it is applicable to

Describe what tools are available to:

◦ Increase tolerance and compliance
◦ Treat the disease and/or disorder
Understand how to impact patient
outcomes by proper utilization of
bilevel and its settings
Why patients fail CPAP:

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CPAP is uncomfortable
Patient may feel CPAP is uncomfortable at higher
pressures despite pressure relief features
COPD patients have trapped air/pressure in their lungs,
which may increase their work of breathing
Patient may need higher levels of ventilatory support
CPAP cannot provide
Why make the switch from CPAP to Bilevel?
Patient Comfort:
 Cannot tolerate CPAP
 On a high CPAP pressure and cannot tolerate it
Ventilation:
 Obstructive disease
 Restrictive disease
 Neuromuscular disease

Comfort/compliance features
◦ Cpap
 Lower pressure
 Ramp
 Pressure relief (Cflex or EPR)
 Waveform (sine vs square)
◦ Bilevel
 Ramp
 Pressure relief (Ipap and Epap)
 Waveform
 Rise time
 Trigger sensitivity
 Cycle sensitivity
 Ti control (controlling the time in inspiration or expiration)
 Pressure support ( muscle unloading)
Inhalation
Cycle
Trigger
Patient
Flow
Exhalation
Delivered
Pressure
IPAP
EPAP
Pressure support (
P)

OSA
Airway problem

CompSA
problem
Airway and Ventilation

Cheyne-Stokes
Ventilation problem

COPD
Ventilation problem

Neuromuscular
Ventilation problem
Can I get Bilevel paid for when it not OSA?
Tools Available in Bilevel for
Specific Diseases

ST device
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Is back-up rate machine (E0471)
Fixed rate – time controlled
Not very comfortable- little synchrony
Square wave- ventilates
Servo ventilator
◦
◦
◦
◦
Is back-up rate machine (E0471)
Should be more comfortable- tries to sync with pt
Sine wave- not trying to ventilate
Very automatic (servo)
CompSA patient
on Servo
CompSA patient
not treated
Central
apneas occur
The ASV algorithm automatically adjusts the
magnitude of pressure support breath by breath to:
◦ Provide minimal, comfortable support during the overbreathing phase (hyperpnea) or during normal breathing
◦ Increase support during the under-breathing phase
(hypopnea or apnea)
VPAP Adapt SV
Patient Flow
Tools Available in Bilevel for
Specific Diseases
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Lung tissue destroyed
Elasticity of lungs
disappearing
Poor functioning
diaphragm
Reliance on accessory
muscles
Air trapping
•May have difficulty exhaling on CPAP
•Extends their inspiratory time
•Asynchrony
•Increases their work of breathing
•Cycling problems (getting into exhalation)
Delayed cycling =
Decrease in
• Expiratory
time
• Lung
emptying
Decreased expiratory time =
Increase in
•
•
•
Auto-PEEP
Missed
triggers
Work of
breathing
Adjustable Trigger Sensitivity
Adjustable Cycle Sensitivity
Patient
Flow
Patient
Flow
EPAP
Very High
Quick to trigger
2.4 L/min
High
More sensitive
4 L/min
Med
Default
6 L/min
Low
Less sensitive
10 L/min
Very Low
Slow to trigger
15 L/min
EPAP
Very High
Quick to cycle
50% of peak
High
More sensitive
35%
Med
Default
25%
Low
Less sensitive
15%
Very Low
Slow to cycle
8%
flow
Problem: Patient requires longer expiratory time (i.e. COPD)
Solution: Best option – Shorten Ti Max time
Additional options – Select higher cycle sensitivity,
Select faster rise time

Rise Time
◦ For comfort
◦ Will affect how pressure “feels” to pt
Square Wave
Easy-Breathe
Tools Available in Bilevel for
Specific Diseases
“However, premature cycling may
also have detrimental effects on
patient-ventilator synchrony.
Premature cycling is simply when
the ventilator terminates the breath
while the patient requires a long
Premature cycling
creates asynchrony
Occurs in restrictive
patients
inspiratory period.”
• Lungs physically
restricted
• Paralysis or muscles
deteriorated
Gentile. Respir Care 2011
An early fall in the absolute flow
rates may trigger the transition to
EPAP prematurely. Certain devices
provide a minimum IPAP time to
ensure that IPAP lasts long enough
to allow delivery of an adequate
tidal volume.
)
4.8.4 Minimum IPAP duration
(if available) may be increased if
the device cycles from IPAP to
EPAP prematurely
(eg, in restrictive chest wall
disorders).
Level A – Consensus
Berry. J Clin Sleep Med 2010
PS 5
PS 10
PS 15
PS 20
• Can assure Tidal Volume while the patient is sleeping
• Is Servo Controlled
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iVAPS – (ResMed)
Intelligent Volume Assured
Pressure Support
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AVAPS (Philips)
Average Volume Assured
Pressure Support
REM Onset
Alveolar ventilation drops
◦ patient moves into REM
sleep
◦ iVAPS rapidly increases PS
Ventilation [– AV –MV –TargetAV ]
Pt. Flow
PS
until target Va is reached
SpO2

CPAP may not be the device of choice for specific patients
Diagnoses will be a big determinant of what PAP machine will be
appropriate for the patient
Goals of therapy will tell you what machine you should use

Bilevel offers a greater amount of tools to:

Tools available
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◦ Stabilize airway
◦ Hypoventilate the patient
◦ Ventilate the patient
◦ Increase comfort of patient
◦ Increase compliance of patient
◦ Increase the chances of the therapy goals being met
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Wave forms
Time cycling
Sensitivity adjustments
Servo algorithms