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Anatomy and Physiology
and Non-invasive Ventilatory Support
Cheryl Needham
Sr. Clinical Marketing Manager
breathing,
•respiratory diseases, and mechanical ventilation
Conflict of Interest Disclosure(s)
I do not have any potential conflicts of interest to
disclose,
• OR
• __X_I wish to disclose the following potential conflicts
of interest:
• ____
•
•
•
•
•
•
Type of Potential Conflict/Details of Potential Conflict
____Grant/Research Support
____Consultant
____Speakers’ Bureaus
____Financial support
__X_Other
Employee of Philips Respironics
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Objectives
• Review anatomy and physiology of the respiratory system
• Discuss the etiology and pathophysiology for the following respiratory
disorders:
– obstructive disorders
– restrictive thoracic disorders
– obesity hypoventilation
– neuromuscular disorders
• Review treatment options for the respiratory management of selected
diseases
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Anatomy and Physiology
•
The Respiratory System:
Breathing and Gas Exchange
Cerebrum
Controller
Brainstem
Spinal Cord
Effector
Respiratory Muscles
Airway Vessels and Function
Result
Sensors/
Feedback
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Gas Exchange
Mechanoreceptors
Chemoreceptors
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Cerebrum
Controller
Brainstem
Nervous System Divisions
Spinal Cord
• Nervous System
– Central
• brain and spinal
cord
– Peripheral
• nerves transmitting
impulses to/from the
brain
• Basic components
– brain, spinal cord, nerves
– neurons are basic cells
that carry impulses from
one part of the body to
another
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Cerebrum
Controller
Brainstem
Spinal Cord
Central Nervous System (CNS)
• Factors that may impact
breathing include:
– drug administration
– changes or damage to the
brain due to various
diseases (ALS, dementia,
stroke)
– loss or severing of motor
neurons
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Cerebrum
Controller
Brainstem
Peripheral Nervous System (PNS)
Spinal Cord
• Further divided into 2 subsystems
– Somatic (voluntary)
– Autonomic (involuntary)
• Somatic System
– controls skeletal muscles
– voluntary movements
Relays signals to and from the brain!
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Cerebrum
Controller
Brainstem
Peripheral Nervous System (PNS)
Spinal Cord
• Autonomic system divided into 2
branches:
– Parasympathetic
• conserves energy and
restores body’s resources
for rest and digestion (breed
or feed)
– Sympathetic
• mobilizes person during
emergency or stress
situations (fight or flight)
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Effector
Respiratory Muscles
Airway Vessels and Function
Respiratory Muscles and Rib Cage
• The diaphragm is the main
muscle for respiration
– primary muscle for inspiration
• There are also muscles found
surrounding the rib cage
– move the rib cage during
inspiration and exhalation
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Effector
Respiratory Muscles
Airway vessels and Function
Respiratory Muscles and Rib Cage
• Function during inspiration:
– diaphragm contracts and moves
downward.
– pressure is lower in the thoracic
cage causing air to come into the
lungs
• Function on exhalation:
– diaphragm relaxes and moves
upward compressing the lungs
– pressure is higher in the lungs
causing air to move out of the lungs
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Effector
Respiratory Muscles
Airway Vessels and Function
Accessory Muscles - Inspiration
• Function to either raise the
ribcage or stabilize it
• May be used for forced or deep
breathing in normal conditions
(i.e., exercise)
• Use of accessory muscles for
resting inspiration is
considered abnormal
– If used, patient may be
having difficulty breathing
http://medicine.ucsd.edu/clinicalmed/lung.htm
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Effector
Respiratory Muscles
Airway Vessels and Function
Accessory Muscles - Expiration
• Expiration should require no
effort due to the normal
function of the lungs
• Any muscle usage for
expiration is considered
abnormal
• Accessory muscles of
expiration include those found
on the
– back, thorax, abdomen
• Aids exhalation by pulling the
ribcage down or supporting it
http://www.emedicine.com/pmr/images/
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Effector
Respiratory Muscles
Airway Vessels and Function
Airway Vessel and Function
• The respiratory system is made up of
2 main sections:
– conducting airway
– gas exchange area
• The conducting airway moves fresh
gas from the atmosphere into the
respiratory system
• The airway is made of a series of
channels that lead the fresh gas to
the gas exchange area:
– alveolar sacs
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Center Court at Wimbledon
vs. Your Lungs
Effector
Respiratory Muscles
Airway Vessels and Function
They have the same surface area!
What do they have in
common?__________________________________
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Result
Gas Exchange
• Goal of inspiration
– move air to the area of the lung
that will allow gas exchange to
occur
• alveolar sac
• Pressure gradients determine if gas
exchange occurs.
• Pressure gradient must exist
– higher in the lungs, lower in the
blood
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Gas Exchange
Result
Gas Exchange
• In addition to fresh gas and
movement of the pulmonary
muscles, the alveolar units
must have blood going past the
alveolar sac
• The combination of fresh gas
and blood allows for gas
exchange to occur
– normal O2 levels for an
adult: 80 – 100 mmHg
– normal PCO2 levels for an
adult: 35 – 45 mmHg
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Gas Exchange
Result
Gas Exchange: Problems
• There can be many reasons why gas exchange does not occur, such as:
– poor perfusion of the pulmonary system
– destruction of the alveolar sacs
– inability to move gas into the alveolar sacs
• decreased lung expansion
• conduction problem with nervous system impulse
• muscular weakness
– combination of factors
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Gas Exchange
Respiratory Disorders in the Sleep Lab
•
Respiratory System Disorders
• Obstructive disorders
– patient will have difficulty
exhaling used gases
• Restrictive disorders
– patient will have difficulty
inhaling fresh gases
• Obesity hypoventilation
• Neuromuscular disorders
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Obstructive - COPD
• A group of abnormal pulmonary
conditions associated with cough,
sputum production, dyspnea,
airflow obstruction, and impaired
gas exchange
– emphysema
– chronic bronchitis
– asthma
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Chronic Bronchitis
COPD
Emphysema
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Asthma
Overlap Syndrome
• Introduced by Dr. David Flenley1
• Overlap Syndrome is used to describe the
association of OSA and COPD
• Overlap syndrome is estimated in about 10 –
15% in COPD population2
• About 30% of COPD patients will experience
nocturnal desaturation,
• Small percentage will have Overlap Syndrome
Flenley DC. Clin. Chest Med. 1985:6(4)651-666
2 McNicolas, W. Chest 2000:117:488-538
1
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Impact of Sleep
• COPD patients may have more hypopneas vs. apneas
• Patients with moderate to severe COPD may have a marked response
to REM sleep states with dramatic drop in oxygenation
• Patients may have nocturnal desaturation without having daytime
desaturation
• Factors that will impact extent of Overlap Syndrome
– Hypoventilation
– Desaturation during NREM & REM sleep
– Alterations in ventilation vs. perfusion with body position
– Daytime PaO2 and PaCO2
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Relationship between OSA and COPD:
Sleep Heart Health Study
• Evaluated polysomnography and spirometry results of 5954 patients
enrolled in SHHS.
• Aim of study:
– evaluate the association between OSA and COPD
– evaluate the impact of desaturation on patients with COPD both
with and without OSA
• A total of 1132 studied had mild obstructive airway disease
Sanders, et al AJRCCM 2003:7 - 14
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Restrictive Thoracic Disorders
My character was
based on a friend of
Walt Disney’s who had
MG
• Neuromuscular disease
– Amyotrophic Lateral Sclerosis (ALS)
– Guillain-Barre’ (GB) and Myasthenia
Gravis (MG)
• Obesity hypoventilation
• Chest wall deformities
– skeletal disorders
– kyphosis/scoliosis
• All forms lead to hypoventilation
of the lung regions and
atelectasis
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Amyotrophic Lateral Sclerosis (ALS): Etiology
• A progressive degenerative
disease that affects nerve cells in
the brain and the spinal cord
• When the motor neurons die, the
ability of the brain to initiate and
control muscle movement is lost
– voluntary muscle action is
progressively lost
ALS is often referred to as
"Lou Gehrig's Disease"
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Etiology and Anatomical Changes
•Weakened bulbar muscles can cause closing of the airway
•Nerve and muscle functions relax during sleep causing underventilation
– complaints of morning headaches, lethargy, and shortness of breath
(SOB)
Living with ALS: Adapting to Breathing Changes, 1997, ALS Assoc.
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Obesity Hypoventilation Syndrome (OHS): Etiology
• Absence of significant lung or
respiratory disease1
• May result from both a defect in
the brain's control over breathing
and excessive weight against the
chest wall
– makes it hard for a person to
take a deep breath
– inefficient breathing leads to
lower PO2 levels and higher
PCO2 levels in the blood when
awake
May be referred to as “Pickwickian Syndrome”
Banerjee, D. and et al. Chest 2007;131;1678-1684
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Signs and Symptoms
• Extreme obesity
• Often exhibit the following:
– tired due to sleep loss
– poor sleep quality
– chronic hypoxia
• Difficulty breathing when supine
• OSA plus OHS may cause
severe O2 desaturation during
sleep
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Complex apnea and central apnea
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Treatment Options
•
Sleep Disordered Breathing
OSA
Central
Hypoventilation
Noninvasive Ventilation
CPAP
BiPAP
Volume Assured
Pressure Support
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Bilevel patient types
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Bi-level S/T mode
• Bi-level support with Spontaneous and Timed mode activated
• This mode is used with patients that require
– Time rate from the device to support their inconsistent respiratory
pattern
– Pressure support to augment their tidal volume when the device
provides a breath to the patient
– Ability to receive
spontaneously initiated breaths
or timed back up breaths from
the device
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Bi-level Pressure Delivery
Bi-level Devices provide pressure with a variable volume delivery
600 cc
455 cc
450 cc
300 cc
VT
P
12 cm H2O
12 cm H2O
12 cm H2O
Over time - static pressure therapy with variable volume delivery may not provide
adequate therapeutic support for progressive disease states  patient conditions:
• ALS
• Overlap Syndrome (COPD + OSA)
• OHS (obesity hypoventilation syndrome)
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Consensus Conference
“…in patients with neuromuscular disease … recent reviews
have cited the advantages of pressure targeted devices for
comfort and their ability to compensate for leaks.”
“pressure targeted systems are not able to guarantee a
minimum minute ventilation.”
Source: Consensus Conference Chest 1999: “Clinical Indications for Noninvasive Positive Pressure Ventilation in Chronic
Respiratory Failure Due to Restrictive Lung Disease, COPD, and Nocturnal Hypoventilation”
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Bi-level with Volume Assurance
• Acts primarily as a bi-level pressure support device but is able to
provide a constant tidal volume.
• Automatically adjusts the pressure support level to maintain a
consistent tidal volume
– Pressure will automatically
increase or decrease to
maintain set tidal volume
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Bi-level with Volume Assurance
• Automatically adjusts the pressure support level to maintain a
consistent tidal volume
• IPAP will automatically increase or decrease
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Volume Assurance with PS is NOT
recommended for patients with periodic breathing
• Treatment of periodic breathing requires a variable breath by breath
response system so the patients PaCO2 stabilizes quickly
– Prevents overshooting or undershooting the PaCO2 breath by
breath
– Does not augment the patients tidal volume consistently
• Volume Assurance with PS does not have a quick variable response to
changes in tidal volume.
– It is designed to adjust and maintain a constant tidal volume with
each breath over time.
– This benefit often seen with patients who have slow declines in their
ventilatory conditions.
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Advanced NIV Titration Goals
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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Sleep Disordered Breathing
OSA
Central
Hypoventilation
Noninvasive Ventilation
CPAP
BiPAP
Auto Servo
Ventilation
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Servo ventilation patient types
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Treatment options for complex sleep apnea
• CPAP + time on therapy to reset chemoreceptors for patient1
– Must qualify with RDI > 5 with symptoms of OSA or RDI > 15
without symptoms 2
– 30-day trial on CPAP then follow up with patient on excessive
daytime sleepiness, if improved keep on CPAP
• No improvement in daytime sleepiness after 30 days, try alternatives
– Medications + CPAP
– Auto Servo Ventilation
– Bi-Level therapy with backup rate
• RAD policy for complex sleep apnea
1 Dernaika T et.al; Chest 2006 s;130(4)129
2 Adult Sleep Apnea Task Force, AASM, ; Journal of Clinical Sleep Medicine 2009; 5(3)
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Servo Ventilation
• Treatment for complicated breathing
patterns such as:
– Central apnea
– Complex apnea
– Periodic breathing such as CSR
• Provides non-invasive ventilatory
support to treat adult patients with OSA
and respiratory insufficiency caused by
central and/or mixed apneas and
periodic breathing.
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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 tolerates, will be
compliant with and makes them much better than they were is an
achievable goal
– Patience is key to successful titrations
– If a change is needed and made, Watch, Wait, Observe and Think
before making any other adjustments
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Why not use auto servo ventilation for a
neuromuscular diseased patient?
• Would continually reset it’s baseline, worsening the
hypoventilation
• Normal target continues to decrease – continues to
under ventilate patient as the night progresses
Ventilation
Time
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Why not use volume assured pressure
support
for
Periodic
Breathing
such
as
•
Cheyne Stokes?
– Volume assurance with PS does not respond fast
enough – event would be over before reaching needed
pressure
– Length of event vs. time of response
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Pearls
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!
Confidential
In contrast to
uncomplicated OSA
patients titrated on
CPAP, the titration
doesn’t END on the
titration night. It is just
the beginning!
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