“SMART”
Technologies
Why are they so
scary?
They’re not so smart
without YOU!
Pamela Minkley RRT, RPSGT, CPFT
Make Sleep a Priority
March 2013
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It’s critical to understand how things work, not
just “know how to do it”
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What makes us breathe?
The stimulus to breathe
awake and asleep
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Respiratory Physiology During Sleep
•
•
•
•
Stimulus to breathe not the same as awake
Response to hypercarbia & hypoxemia blunted
Physiology varies NREM vs REM
Cardiovascular changes effect gas delivery and
exchange
• Respiratory and cardiovascular disease disrupt
normal physiology
• Some pathologic breathing patterns come and
go throughout the sleep period.
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Normal Awake Stimulus to Breathe
• Hypercapnia
– PaCO2 changes quickly
– HCO3 changes slowly
– Both affect the pH of the blood
• Hypoxia
– SaO2 and PaO2
• Carotid and aortic bodies
• Stretch, “J”, and other receptors
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Physiologic Changes in Respiratory Control with Sleep
Inactive
Active
Transitiona
l Sleep*
Stage 2
Slow
Wave
Sleep
REM Sleep
Major Influence on
breathing
Metabolic
Behavior
Metabolic**
Metabolic
Metabolic
Nonmetabolic
Pattern of breathing
Regular
Irregular
Periodic
Regular
Regular
Irregular
Central
Apneas/Hypopneas
Absent
Absent
Often
Rare
Absent
Frequent
Response to
metabolic stimuli
Present
Decreased
Variable
Mild
Decrease
Mild
Decrease
Mod.
Decrease
Chest wall movement
Phasic
Phasic
Phasic
Phasic
Phasic
Paradoxical
* Transitional sleep refers to the period of sleep between wakefulness and continuous stage I sleep or established stage II sleep.
** The metabolic regulation during the transition between sleep and wake is affected by an upward shift in pCO2 set point and the
gain of the pCO2 response.
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Identify these breathing patterns.
Opioids
How did you do
it?
How would a
computer do it?
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What do you see on the PSG?
O
S
A
Note square wave pattern of OSA recovery breathing. Different from CSR.
Oximetry patterns.
OSA
Normal
CSA
How would you “explain” that to a computer?
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Triangular
Paradoxical
Central or obstructive hypopnea? Likely response to CPAP?
How would a computer know what to do?
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PAP Therapy: Decision Making Tree
OSA
Hypoventilation
CSA
Obstructive Events
Try to breathe but can’t
get enough in
Impaired Gas Exchange
Oxygen drops/Carbon
Dioxide rises
Central Events
Don’t breathe at all or
pattern is mixed up
What would this
look like on a PSG?
What would this
look like on a PSG?
HST?
HST?
Therapy download?
Therapy download?
What would this
look like on a PSG?
HST?
Therapy download?
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Hypoventilation
would look like
THIS!
Volume and flow change slowly over time in hypoventilation,
ASV algorithmic target will gradually lower and not trigger a response
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THEN: autoSV
Advanced delivers CPAP pressure only
AVAPs Algorithm
< 1 cmH2O / min
increase
IPAP Setting
Pressure
Desired Volume
Volume
Not a breath by breath change to stabilize the breathing pattern like aSV
Delivers a targeted tidal volume. Focus is on ventilation not stabilizing the
breathing pattern.
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PAP Therapy: Decision Making Tree
OSA
Hypoventilation
CSA
Obstructive Events
Try to breathe but can’t
get enough in
Impaired Gas Exchange
Oxygen drops/Carbon
Dioxide rises
Central Events
Don’t breathe at all or
pattern is mixed up
What would this
look like on a PSG?
What would this
look like on a PSG?
HST?
HST?
Therapy download?
Therapy download?
What would this
look like on a PSG?
HST?
Therapy download?
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OSA
Periodic
Breathing
The
Bucket
Theory
Let’s talk about breathing during
sleep
Opioid
CSA
Trauma
CSA
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Complex Sleep Apnea Components
OSA
Central SDB
Obstructive apneas
Obstructive hypopneas
Noninvasive Ventilation
Periodic Breathing
CSR
CPAP
APAP
BiLevel
Auto Servo
Ventilation
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Hypoventilation
Central Apnea
Central Hypopnea
Volume Assured Pressure
Support with Rate
PAP Therapy: Decision Making Tree
OSA
Hypoventilation
Obstructive Events
Open the Airway
Impaired Gas Exchange
Ventilate
CPAP
Volume
Assured
Pressure
Support w/Rate
APAP
Bi-level
CSA
Central Events
Stabilize Breathing Pattern
Auto Servo
Ventilation
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BiPAP autoSV Advanced
Theory ofto
Operation
Algorithms
match the pathologies
Servo Ventilation Algorithm
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• CPAP
PAP Therapy for
Patients with OSA
─ One level of pressure on inspiration and exhalation
─ Device may have the option to provide pressure relief in
early exhalation
• Auto titration therapy
cmH20
CPAP
─ Device pressure is adjusted based on airway dynamics and
device algorithm
Auto CPAP
cmH20
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PAP Therapy for Patients with OSA/SDB
• Bi-level therapy
Flow pattern could look different depending
on position and spontaneous vs machine
breath. Why?
─ One level of pressure on inspiration and lower level of
HowPS
would
graphic
look
for AVAPS?
pressure on expiration.
the this
same
every
breath
Bi-Level
cmH20
• Auto Servo Ventilation
─ Device pressure is adjusted based on airway dynamics,
patient respiratory effort and flow and device algorithm. PS
varies according to need.
Auto SV
cmH20
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PAP Therapy for Patients with CSR
CO2 waxing and waning with under and over ventilation
Airflow
Pressure
Support
CO2 Stable , Breathing pattern stable,
Patient breathes on own with normal variability
Patient
Airflow
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What therapy would you need for each breathing
pattern shown?
Most patients
will bring a
unique mix of
breathing
patterns!
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Upper airway compromise
Respiratory Control Issues
Involuntary/Autonomic
Control
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Auto Servo Ventilation
Theory of Operation
Auto EPAP with Servo Ventilation Algorithm
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Auto EPAP Algorithm
Sophisticated Three Layered Algorithm:
Safety Net
Primary Function
Pro Active
Analysis
Exceptions
Patient Not Responsive
Leak Tolerance
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Servo Ventilation Algorithm
4 Minutes
On a breath by breath basis flow and/or volume is captured
Peak flow or volume is monitored over a moving 4 minute window
As 1 breath is added, the initial breath falls off (“rolling 4 minute window”)
At every point within this 4 minute period an Average Peak Flow is calculated
The Peak flow target is established around that average and is based on the
patient’s needs
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Servo Ventilation Algorithm – Normal Breathing
IF: Peak flow is at target
THENASV delivers CPAP pressure only
I wonder what
hypoventilation
would look like?
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Servo Ventilation Algorithm –
Hypoventilation
would lookBreathing
like
Normal
THIS!
IF: Peak flow changes slowly over time like hypoventilation,
target will gradually lower and peak flow will be at target
THEN: autoSV Advanced delivers CPAP pressure only
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Servo Ventilation Algorithm – Decreased Flow
IF: Peak flow falls below target
THEN: autoSV Advanced increases pressure support
•Aggressive, quick changes meet peak flow target
•Flow or volume target
is
…Over ventilation is avoided
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Assured Volume Algorithm
< 1 cmH2O / min
increase
IPAP Setting
Pressure
Desired Volume
Volume
Automatically adjusts the pressure support level to maintain a consistent tidal
volume
Not a breath by breath change to stabilize the breathing pattern like aSV
IPAP will automatically increase or decrease to meet Vt target
Delivers
a targeted tidal volume. Focus is on ventilation not stabilizing
the
SLOW increases, not breath by breath (
)
breathing
pattern.
Assured
tidal volume (
)
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Auto EPAP - Life is all about compromise!
25 Max pressure
15 EPAPmax
OA
H
S
S
H
OA
S
5
EPAPmin
S = Snore H = Hypopnea OA = Obstructive apnea
Pearl
SV algorithm works ‘on top’ of Auto EPAP
The higher the EPAP, the less “space” the ASV algorithm has to work
Complicated
The Complex
Sleep Apnea Bucket List
X
Pathologies
Preferred Treatment
OSA
CPAP, APAP
Periodic Breathing
aSV or AVAPS
Cheyne Stokes type Periodic
Breathing
aSV
Central Sleep Apnea
aSV or AVAPS
Central Hypopnea
aSV or AVAPS
Hypoventilation
AVAPS
CPAP emergent “Central Sleep
Apnea”
Depends. Check baseline PSG. May
change with treatment.
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What do you see?
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What do you see?
AM060606
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What do you see?
Proportionate changes in flow and effort.
Likely central in nature
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What do you see?
AM060606
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Identify these breathing patterns.
Opioids
How did you do
it?
How would a
computer do it?
Was it easier
this time?
40
What do you see on the PSG?
O
S
A
Note square wave pattern of OSA recovery breathing. Different from CSR.
Oximetry patterns.
OSA
Normal
CSA
How would you “explain” that to a computer?
41
Triangular
Paradoxical
Central or obstructive hypopnea? Likely response to CPAP?
How would a computer know what to do?
42
BiPAP
autoSV
Advanced
Key aSV
terms
and concepts
(because
thisand
seems
to be a problem for us)
Terms
Definitions
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Terms you need to understand
• EPAPmin
– The EPAP will not drop below this pressure
• EPAPmax
– The EPAP will not go above this pressure even if events are detected
• Max pressure
– The maximum pressure the device will deliver even if the algorithm indicates
a pressure increase is needed
• Peak Inspiratory Pressure (PIP)
– The maximum pressure reached on inspiration to deliver the pressure support
determined by the algorithm
• PSmin
– The minimum amount of pressure support delivered each breath (i.e.
minimum difference between the EPAP and the PSmin setting)
• PSmax
– The maximum amount of pressure support that can be delivered (i.e.
maximum difference between the EPAP and the PIP)
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Note: This value may limit the amount of Inspiratory pressure delivered
Let’s take a look at these terms graphically
25 Max pressure
Auto EPAP - Looks like Auto CPAP!
PSmax
PSmax
15 cm H2O
15 EPAPmax
PSmin
PSmin 3 cm H2O
Auto EPAP
5
EPAPmin
We will discuss this more when we talk about titration
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Let’s take a look at these terms graphically
Auto EPAP - Looks like Auto CPAP!
25 Max pressure
15 EPAPmax
PSmin
5
PSmax
PSmax
10 cm H2O
PSmin 0cm H2O
Auto EPAP
EPAPmin
We will discuss this more when we talk about titration
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Understanding what “success” looks like
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ASV Stabilizes Ventilation after an arousal. This is the intended
response and does NOT require an adjustment in settings!
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Titration goals
1. Keep the upper airway open (airway
management).
2. Stabilize breathing patterns by monitoring the
patient’s response to therapy.
3. Adjust user-set parameters as needed for optimal
therapy efficacy and adherence.
The goals should be individualized to meet the
needs of each patient.
It is likely each titration will be
somewhat unique
Pearl
Exquisitely designed algorithms in partnership with your clinical
experience,49knowledge and observations AND a clear definition
of “success” results in SUCCESSFUL THERAPY
Titration Protocol
Titration Goals:
Airway management, stabilize breathing patterns
by
monitoring patient’s response
and
adjusting user set parameters if needed
for
optimal therapy efficacy and adherence
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Titration Protocol References
This protocol is consistent with device validation
studies and the following AASM clinical guidelines:
1. Clinical Guidelines for the Manual Titration of Positive
Airway Pressure in Patients with Obstructive Sleep Apnea; J.
Clin. Sleep Med 2008, 4(2)157-171
2. Clinical Guideline for the Evaluation, Management and
Long-term Care of Obstructive Sleep Apnea in Adults; J.
Clin. Sleep Med 2009, 5(3)263-276
3. Best Clinical Practices for the Sleep Center Adjustment of
Noninvasive Positive Pressure Ventilation (NPPV) in Stable
Chronic Alveolar Hypoventilation Syndromes, Accepted for
publication J.Clin.Sleep Med Aug. 19, 2010
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Complex sleep apnea patients may challenge
even the most experienced, skilled sleep
technologist!
• Complex sleep apnea patients have multiple pathologies each requiring
the attention of the technologist
• Helpful hints for complex sleep apnea titrations
– Obstructive apneas, obstructive hypopneas, central apneas,
hypopneas, RERAs and periodic breathing may all be present
intermittently throughout the sleep period
– Making the patients 100% normal may not be a realistic goal
– Optimizing therapy within a range the patients tolerate, will be
compliant with and are much better than they were is an achievable
goal
– Patience is key to successful titrations
– If a change is needed, Watch, Wait, Observe and Think before
making any52other adjustments. If the change isn’t effective, put it
back to the original setting and wait before you try something else.
Patient Follow-up
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Titration is just the beginning of successful
therapy
• Continuing clinical assessment is essential for:
– Compliance and efficacy
– Achieving long term benefits, lower morbidity/mortality
• Complex sleep apnea patient may be the most
challenging to follow up because they have multiple,
changing pathologies requiring therapy
– Achieving optimal therapy and meeting patient
comfort needs can be a challenge that requires
ongoing assessment of therapy device downloads
and interviews with the patient
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Advanced technology and YOU
The perfect combination!
AUTO EPAP
SV algorithm works ‘on top’ of
Auto EPAP
How do you think the patient’s
physiology will change during the first
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weeks of ASV use?
Adaptive Servoventilation (ASV) in Patients with
Sleep Disordered Breathing Associated with
Chronic Opioid Medications for Non-Malignant
Pain, Robert J. Farney, M.D; J Clin Sleep Med. 2008 August 15; 4(4):
311–319.
– Retrospective study
• Conclusions:“Due to residual respiratory events and
hypoxemia, ASV was considered insufficient therapy
in these patients
• Persistence of obstructive events could be due to
suboptimal pressure settings (end expiratory and/or
maximal inspiratory). Residual central events could be
related to fundamental differences in the pathophysiology
of CSR compared to opioid induced breathing
disturbances.”
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Complex physiology and
pathology makes many
patients difficult to treat.
They are a moving target.
Many times, making them
BETTER THAN THEY
WERE on the titration
night IS a success!
Pearls
In contrast to
uncomplicated OSA
patients titrated on
CPAP, the complex
patient’s titration
doesn’t END on the
titration night. It is just
the beginning!
Know and
understand SMART
technology.
It needs your
understanding and
guidance to
succeed
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