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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
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Anatomy and Physiology and Non-invasive Ventilatory SupportCheryl NeedhamSr. 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_OtherEmployee of Philips Respironics
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
The Respiratory System:Breathing and Gas Exchange Cerebrum Brainstem Spinal Cord Controller Respiratory Muscles Airway Vessels and Function Effector Gas Exchange Result Mechanoreceptors Chemoreceptors Sensors/ Feedback
Cerebrum Brainstem Spinal Cord Controller Nervous System Divisions • 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
Cerebrum Brainstem Spinal Cord Controller 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
Cerebrum Brainstem Spinal Cord Controller Peripheral Nervous System (PNS) • Further divided into 2 sub-systems • Somatic (voluntary) • Autonomic (involuntary) • Somatic System • controls skeletal muscles • voluntary movements Relays signals to and from the brain!
Cerebrum Brainstem Spinal Cord Controller Peripheral Nervous System (PNS) • 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)
Respiratory Muscles Airway Vessels and Function Effector 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
Respiratory Muscles Airway vessels and Function Effector 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
Respiratory Muscles Airway Vessels and Function Effector 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
Respiratory Muscles Airway Vessels and Function Effector 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/
Respiratory Muscles Airway Vessels and Function Effector 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
Respiratory Muscles Airway Vessels and Function Effector Center Court at Wimbledon vs. Your Lungs What do they have in common?__________________________________ They have the same surface area!
Gas Exchange 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
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
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
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
Obstructive - COPD • A group of abnormal pulmonary conditions associated with cough, sputum production, dyspnea, airflow obstruction, and impaired gas exchange • emphysema • chronic bronchitis • asthma Chronic Bronchitis COPD Emphysema 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 1 Flenley DC. Clin. Chest Med. 1985:6(4)651-666 2 McNicolas, W. Chest 2000:117:488-538
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
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
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
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"
Etiology and Anatomical Changes • Weakened bulbar muscles can cause closing of the airway • Nerve and muscle functions relax during sleep causing under- ventilation • complaints of morning headaches, lethargy, and shortness of breath (SOB) Living with ALS: Adapting to Breathing Changes, 1997, ALS Assoc.
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 PCO2levels in the blood when awake May be referred to as “Pickwickian Syndrome” Banerjee, D. and et al. Chest 2007;131;1678-1684
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
Sleep Disordered Breathing Hypoventilation OSA Central Noninvasive Ventilation CPAP BiPAP Volume Assured Pressure Support
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 receivespontaneously initiated breaths or timed back up breaths from the device
Bi-level Devices provide pressure with a variable volume delivery Bi-level Pressure Delivery 600 cc 455 cc 450 cc 300 cc VT P • 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) 12 cm H2O 12 cm H2O 12 cm H2O
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 ableto 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”
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 Bi-level with Volume Assurance
Bi-level with Volume Assurance • Automatically adjusts the pressure support level to maintain a consistent tidal volume • IPAP will automatically increase or decrease
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.
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
Sleep Disordered Breathing Hypoventilation OSA Central Noninvasive Ventilation CPAP BiPAP Auto Servo Ventilation
Treatment options 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) • 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
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.
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
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
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
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! In contrast to uncomplicated OSA patients titrated on CPAP, the titration doesn’t END on the titration night. It is just the beginning!