“smart” technologies why are they so scary? they’re not so smart without you!

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Pamela Minkley RRT, RPSGT, CPFT

March 2013

“SMART” TechnologiesWhy are they so scary?

They’re not so smart without YOU!

Make Sleep a Priority

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It’s critical to understand how things work, not just “know how to do it”

What makes us breathe?The stimulus to breatheawake 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

Major Influence on breathing

Pattern of breathing  

Central Apneas/Hypopneas

Response to metabolic stimuli

Chest wall movement

* 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.

Inactive Active Transitional Sleep*

Stage 2 Slow Wave Sleep

REM Sleep

Metabolic

Regular

Absent

Present

Phasic

Behavior

Irregular

Absent

Decreased

Phasic

Metabolic**

Periodic

Often

Variable

Phasic

Metabolic

Regular

Rare

Mild Decrease

Phasic

Metabolic

Regular

Absent

Mild Decrease

Phasic

Non-metabolic

Irregular

Frequent

Mod. Decrease

Paradoxical

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Identify these breathing patterns.

AB

C

DHow did you do it?How would a computer do it?

OSA

CSR

CA

BiotsOpioids

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O

S

A

CSA

OSA

Normal

What do you see on the PSG?

Note square wave pattern of OSA recovery breathing. Different from CSR.Oximetry patterns.

How would you “explain” that to a computer?

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Central or obstructive hypopnea? Likely response to CPAP?

How would a computer know what to do?

TriangularParadoxical

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PAP Therapy: Decision Making Tree

OSA

Obstructive EventsTry to breathe but can’t

get enough in

What would this look like on a PSG?

HST?Therapy download?

Impaired Gas ExchangeOxygen drops/Carbon

Dioxide rises

CSA

Central EventsDon’t breathe at all or

pattern is mixed up

Hypoventilation

What would this look like on a PSG?

HST?Therapy download?

What would this look like on a PSG?

HST?Therapy download?

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Volume and flow change slowly over time in hypoventilation, ASV algorithmic target will gradually lower and not trigger a response

THEN: autoSV Advanced delivers CPAP pressure only

Hypoventilation would look like

THIS!

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< 1 cmH2O / min increase

AVAPs Algorithm

Desired Volume Volume

IPAP Setting Pressure

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

Obstructive EventsTry to breathe but can’t

get enough in

What would this look like on a PSG?

HST?Therapy download?

Impaired Gas ExchangeOxygen drops/Carbon

Dioxide rises

CSA

Central EventsDon’t breathe at all or

pattern is mixed up

Hypoventilation

What would this look like on a PSG?

HST?Therapy download?

What would this look like on a PSG?

HST?Therapy download?

Central

Hypopneas

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Periodic Breathing

Opioid CSA

OSAHypoventilation

The

Bucket

TheoryTrauma

CSAOpioidCSALet’s talk about breathing during

sleep

Central ApneaCentral Hypopnea

Auto Servo Ventilation Volume Assured Pressure

Support with Rate

Noninvasive Ventilation

CPAPAPAP

BiLevel

Complex Sleep Apnea Components

OSA Central SDB Hypoventilation

Periodic BreathingCSR

Obstructive apneas Obstructive hypopneas

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PAP Therapy: Decision Making Tree

OSA

Obstructive EventsOpen the Airway

CPAPAPAP

Bi-level

Impaired Gas ExchangeVentilate

Auto Servo Ventilation

Volume Assured Pressure

Support w/Rate

CSA

Central EventsStabilize Breathing Pattern

Hypoventilation

BiPAP autoSV AdvancedTheory of OperationServo Ventilation Algorithm

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Algorithms to match the pathologies

PAP Therapy for Patients with OSA

• CPAP ─ One level of pressure on inspiration and exhalation─ Device may have the option to provide pressure relief in

early exhalation

• Auto titration therapy─ Device pressure is adjusted based on airway dynamics

and device algorithm

21cmH20

Auto CPAP

cmH20

CPAP

PAP Therapy for Patients with OSA/SDB• Bi-level therapy

─ One level of pressure on inspiration and lower level of pressure on expiration. PS the same every breath

• Auto Servo Ventilation ─ Device pressure is adjusted based on airway dynamics,

patient respiratory effort and flow and device algorithm. PS varies according to need.

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cmH20

Bi-Level

cmH20

Auto SV

Flow pattern could look different depending on position and spontaneous vs machine breath. Why?

How would this graphic look for AVAPS?

PAP Therapy for Patients with CSR

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CO2 waxing and waning with under and over ventilation

CO2 Stable , Breathing pattern stable, Patient breathes on own with normal variability

Pressure Support

Airflow

PatientAirflow

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What therapy would you need for each breathing pattern shown?

AB

C

DMost patients will bring a unique mix of breathing patterns!

OSA

CSR

CA

Biots

Involuntary/Autonomic Control

Upper airway compromise

Respiratory Control Issues

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Auto Servo VentilationTheory of Operation

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Auto EPAP with Servo Ventilation Algorithm

Pro Active Analysis Leak Tolerance

Patient Not Responsive

Sophisticated Three Layered Algorithm: Safety Net Exceptions

Primary Function

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Auto EPAP Algorithm

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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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IF: Peak flow is at target THENASV delivers CPAP pressure only

Servo Ventilation Algorithm – Normal Breathing

I wonder what hypoventilation would look like?

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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

Servo Ventilation Algorithm – Normal BreathingHypoventilation would look like

THIS!

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IF: Peak flow falls below target THEN: autoSV Advanced increases pressure support

Servo Ventilation Algorithm – Decreased Flow

•Aggressive, quick changes meet peak flow target•Flow or volume target is conservative…Over ventilation is avoided

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< 1 cmH2O / min increase

Assured Volume Algorithm

Desired Volume Volume

IPAP Setting Pressure

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.

Automatically adjusts the pressure support level to maintain a consistent tidal volume

IPAP will automatically increase or decrease to meet Vt targetSLOW increases, not breath by breath (conservative increases)Assured tidal volume (aggressive pressure support)

H

S S

OA

SH OA

PearlSV algorithm works ‘on top’ of Auto EPAPThe higher the EPAP, the less “space” the ASV algorithm has to work

- Life is all about compromise!

Max pressure

EPAPmax

EPAPminS = Snore H = Hypopnea OA = Obstructive apnea

Auto EPAP

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The Complex Sleep Apnea Bucket List

Pathologies Preferred TreatmentOSA CPAP, APAP

Periodic Breathing aSV or AVAPSCheyne Stokes type Periodic Breathing aSV

Central Sleep Apnea aSV or AVAPS

Central Hypopnea aSV or AVAPS

Hypoventilation AVAPSCPAP emergent “Central Sleep Apnea”

Depends. Check baseline PSG. May change with treatment.

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ComplicatedX

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What do you see?

36AM060606

What do you see?

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What do you see?

Proportionate changes in flow and effort. Likely central in nature

38AM060606

What do you see?

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Identify these breathing patterns.

AB

C

DHow did you do it?How would a computer do it?Was it easier this time?

OSA

CSR

CA

BiotsOpioids

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O

S

A

CSA

OSA

Normal

What do you see on the PSG?

Note square wave pattern of OSA recovery breathing. Different from CSR.Oximetry patterns.

How would you “explain” that to a computer?

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Central or obstructive hypopnea? Likely response to CPAP?

How would a computer know what to do?

TriangularParadoxical

BiPAP autoSV AdvancedTerms and Definitions

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Key aSV terms and concepts(because this seems to be a problem for us)

Terms you need to understand

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• 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)

Note: This value may limit the amount of Inspiratory pressure delivered

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EPAPmin

EPAPmax

Max pressure

PSmax 15 cm H2O

PSmin 3 cm H2O

Let’s take a look at these terms graphically

We will discuss this more when we talk about titration

PSmin

Auto EPAP - Looks like Auto CPAP!

Auto EPAP

PSmax

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EPAPmin

EPAPmax

Max pressure

PSmax 10 cm H2O

PSmin 0cm H2O

Let’s take a look at these terms graphically

We will discuss this more when we talk about titration

PSmin

Auto EPAP - Looks like Auto CPAP!

Auto EPAP

PSmax

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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!

Titration goals1. 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

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PearlExquisitely designed algorithms in partnership with your clinical

experience, knowledge and observations AND a clear definition of “success” results in SUCCESSFUL THERAPY

Titration Protocol

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Titration Goals:

Airway management, stabilize breathing patterns

monitoring patient’s response

optimal therapy efficacy and adherence

for

and

by

adjusting user set parameters if needed

Titration Protocol ReferencesThis 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 any other adjustments. If the change isn’t effective, put it back to the original setting and wait before you try something else.

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Patient Follow-up

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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SV algorithm works ‘on top’ of Auto EPAP

AUTO EPAP

Advanced technology and YOUThe perfect combination!

How do you think the patient’s physiology will change during the first 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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Pearls

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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!

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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