Overview of the SleepDisordered Breathing SDB and Positive
Overview of the Sleep-Disordered Breathing (SDB) and Positive Airway Pressure (PAP) therapy Kristan Rogers BSc (Hons), RPSGT RESMED © Res. Med 2000
Agenda n Sleep-disordered breathing (SDB) n n n n RESMED Definition Clinical features and symptoms Physiology of OSA Consequences of untreated sleep apnea Diagnosing SDB Treating SDB with positive airway pressure (PAP) Maximizing compliance to PAP therapy © Res. Med 2002
Sleep disordered breathing (SDB) RESMED © Res. Med 2002
Sleep disordered breathing (SDB) n SDB is a general term that encompasses a number of breathing disorders during sleep n n n Obstructive sleep apnea (OSA) is the most common form of SDB in the general population n RESMED Obstructive sleep apnea (OSA) Central sleep apnea (CSA) Cheyne-Stokes respiration (CSR) nocturnal hypoventilation snoring 4% females, 9% males (Young et al. , 1993) © Res. Med 2002
Definition of Terms n Apnea - cessation of flow > 10 s n n n Hypopnea - reduction in flow >30% for >10 s most ‘respiratory events’ associated with n n RESMED obstructive: upper airway collapse, continued respiratory effort central: patent upper airway, no respiratory effort mixed: central and obstructive component oxygen desaturation and/or arousals from sleep © Res. Med 2002
Definition of Terms n Cheyne-Stokes Respiration n RESMED Crescendo and decrescendo pattern of breathing with alternate periods of central hypopneas/apneas and hyperventilation © Res. Med 2002
Normal Respiration RESMED © Res. Med 2002
Obstructive Sleep Apnea (OSA) RESMED © Res. Med 2002
Central Sleep Apnea (CSA) RESMED © Res. Med 2002
Cheyne-Stokes Respiration (CSR) RESMED © Res. Med 2002
Pathophysiology of SDB n Upper airway n n n Respiratory drive n n n chest wall neuromuscular Lungs (blood/gas exchange): COPD n n RESMED response to blood gases Lung mechanics n n muscle tone structure inadequate ventilation perfusion mismatch © Res. Med 2002
Obstructive sleep apnea (OSA) n Repeated cessation of breathing during sleep due to partial or complete collapse of the upper airway n n “Stereotypical” patient will be male, obese and hypertensive n RESMED continuing respiratory effort oxygen desaturation arousals from sleep also common in females and children © Res. Med 2002
Normal Breathing Simple Snoring Obstructive Apnea RESMED © Res. Med 2002
Clinical features of OSA n n n n RESMED Excessive daytime sleepiness Loud snoring Witnessed apneas Nocturnal choking and coughing Intellectual deterioration Impotence Short term memory loss Social and marital problems © Res. Med 2002
Predisposing factors for OSA n n n Familial Sex Alcohol Obesity Craniofacial characteristics Endocrine and metabolic disorders n n n RESMED hypothyroidism acromegaly Marfan’s syndrome © Res. Med 2002
OSA Prevalence and Consequences n n n RESMED At ~ 10% prevalence - comparable to the prevalence of asthma and diabetes in the general population (6 -12%) Awareness of OSA is low (less than 5% diagnosed and treated) Major contributor to cerebrovascular (stroke/TIA) and cardiovascular (heart disease) disability and death © Res. Med 2002
Consequences of OSA (1) n Physiological n n n RESMED Arousals, sleep fragmentation, excessive daytime sleepiness Altered blood gases Compromised cardiac function Increased blood coagulability Dose-response relationship between SDB and hypertension © Res. Med 2002
Consequences of OSA (2) n Cost/public health burden n n RESMED 15 times more likely to have an MVA Accidents at home and at work Reduced productivity at work Utilize more healthcare resources © Res. Med 2002
Sp. O 2 BP Airflow Resp. effort RESMED © Res. Med 2002
Complications of OSA Cross-sectional results of the Sleep Heart Health Study (n=6, 424) n n mild to moderate SDB prevalent 16% reported at least one manifestation of CVD Heart failure Stroke Coronary heart disease RESMED Relative Odds Ratio 2. 38 (1. 22 -4. 62) 1. 58 (1. 02 -2. 46) 1. 27 (0. 99 -1. 62) Shahar et al AJRCCM 2001 © Res. Med 2002
Diagnosing sleep disordered breathing (SDB) RESMED © Res. Med 2002
Diagnosing SDB n Full nocturnal polysomnography (PSG) n n Portable sleep study systems n n RESMED Ward or home studies Reduced channel study n n Laboratory based Respiratory Ward or home studies Overnight oximetry Medical history and questionnaires © Res. Med 2002
Respiratory study – Apneas and hypopneas RESMED © Res. Med 2002
PSG for nocturnal hypoventilation syndromes Normal diagnostic study plus some or all of the following measurements: n Transduced airflow/pressure n n Diaphragm EMG n n n RESMED Discriminates obstructive from central events more effectively than thermistors Work of breathing Sternocleidomastoid (SCM) or other accessory muscle activity Transcutaneous CO 2 (Tc. CO 2) © Res. Med 2002
Diagnosing hypoventilation What to look for n Using accessory muscles during NREM n Presence of snore or obstruction in NREM n Severe sleep fragmentation n Inability to maintain REM sleep n Nature of abnormal breathing in REM n RESMED Hypoventilation or central apneas © Res. Med 2002
Discriminating hypoventilation from upper airway obstruction n Identify between obstructive and central events Observe flattening of the inspiratory flow-time curve Determine if the patient hypoventilates n n n RESMED Characterized by a decrease in the amplitude of the flow-time curve Flattening will not be present Measure Sp. O 2 and Tc. CO 2 for additional information about nocturnal hypoventilation © Res. Med 2002
Flow-Time Curve Representation of the flow-time curve for normal airflow, partially obstructed airflow, and hypoventilation. Graph courtesy of Amanda Piper, Ph. D RESMED © Res. Med 2002
Sleep apnea severity - adults n AHI - Apnea/Hypopnea Index n Number of apneas and/or hypopneas per hour of sleep (or study time) normal range 0 -5 n mild 5 -15 n moderate 15 -30 n severe >30 n n Daytime symptoms n RESMED Excessive daytime sleepiness © Res. Med 2002
Treating sleep disordered breathing with Positive Airway Pressure (PAP) therapy RESMED © Res. Med 2002
Treating SDB with Positive Airway Pressure (PAP) therapy n n RESMED Most widely accepted and effective therapy available for the treatment of OSA PAP first described as a treatment for OSA in 1981 by Professor Colin Sullivan, Australia Works by supplying lightly pressurized air to the upper airway to ‘air-splint’ the airway open from the inside Pressure required by each individual highly variable © Res. Med 2002
Positive Airway Pressure (PAP) therapy options n Continuous PAP (CPAP) titration n n Bi-level titration n Patients unable to tolerate high CPAP pressures Patients with obstructive or restrictive lung disease Auto-titration n RESMED Uncomplicated OSA patients © Res. Med 2002
CPAP therapy RESMED © Res. Med 2002
Fixed CPAP Devices Fixed pressure throughout the night. 10 cm H 2 O CPAP Devices provide a single, The intent of CPAP is to splint fixed pressure throughout the open the upper airway to relieve night. obstruction. RESMED © Res. Med 2002
CPAP therapy Aim and effects of CPAP therapy n n n Reduce AHI Stabilize Sp. O 2 Improve sleep quality n n RESMED Reduce daytime sleepiness Improve cardiac function Improve nocturia Improve cognitive function © Res. Med 2002
CPAP therapy Determining the correct pressure n Patient spends one night in sleep laboratory n Full PSG n Pressure increased in response to apneas, hypopneas, snoring and other respiratory events n ‘Correct’ pressure is the pressure that abolishes all respiratory events while the patient is in REM sleep while supine RESMED © Res. Med 2002
Bi-level therapy RESMED © Res. Med 2002
Principle of Bi-level Pressure Delivery IPAP EPAP Bi-level systems deliver a higher pressure on inspiration (IPAP) and a lower pressure on expiration (EPAP). n n IPAP acts as pressure support and augments the patient’s effort, leading to improved alveolar ventilation. EPAP is used to splint open the upper airway to maintain upper airway patency. RESMED © Res. Med 2002
Bi-level PAP therapy Aim and effects of Bi-level PAP therapy (1) n n n Reduce AHI Stabilize Sp. O 2 Improve sleep quality n n n RESMED Reduce daytime sleepiness Improve cardiac function Improve nocturia Improve cognitive function Improve activities of daily living © Res. Med 2002
Bi-level PAP therapy Aim and effects of Bi-level PAP therapy (2) n Improve gas exchange n n n RESMED decrease CO 2 and increase O 2 Rest respiratory muscles Stabilize upper airway Improve quality of life/exercise tolerance Prevent cardiovascular consequences of nocturnal hypercapnia and hypoxia Decrease office visits, hospitalizations, and hospital lengths of stay © Res. Med 2002
Bi-level PAP therapy Determining the correct pressures n n n RESMED Stay with patient and hold mask in place Start with EPAP at ~4 cm. H 2 O and IPAP at 8 cm. H 2 O Independently adjust inspiratory pressures (IPAP) to augment patient’s inspiratory efforts Independently adjust expiratory pressures (EPAP) to maintain control of the upper airway while gaining the benefits of end expiratory pressure (PEEP) Achieve Sp. O 2 > 90 % © Res. Med 2002
Auto-titration RESMED © Res. Med 2002
Auto-titration Varying pressure throughout the night. 4 cm H 2 O Beginning of obstruction Auto-titration devices automatically adjust the pressure in response to changes in the patients airway. RESMED n n Act pre-emptively to prevent upper airway obstruction. Results in lower mean-pressure - more comfortable for patient. © Res. Med 2002
Auto-titration PAP therapy Aim and effects of Auto-titration PAP therapy n n n Reduce AHI Stabilize Sp. O 2 Improve sleep quality n n n RESMED Reduce daytime sleepiness Improve cardiac function Improve nocturia Improve cognitive function Improve activities of daily living © Res. Med 2002
Auto-titration PAP therapy Choosing the correct pressure n A patients pressure requirements change on a continual basis n n n RESMED Sleep state Sleep position Lifestyle Weight loss or weight gain Illness The pressure determined during a manual titration may not provide optimal therapy on a mid- to long term basis © Res. Med 2002
Auto-titration PAP therapy Choosing the correct pressure n Device monitors status of the upper airway on a breath by breath basis by looking at the inspiratory flow time curve n n n RESMED A smooth curve indicates an open, unobstructed airway A flattened curve indicates partial upper airway obstruction (airflow limitation) Device will increase pressure in response to apneas, airflow limitation and snoring © Res. Med 2002
Inspiratory Flow-Time Curve n n Defined as inspiratory airflow (y axis) measured over time (x axis) In a normal breath, this chart would appear as a classic bell shape curve Open, unobstructed airway FLOW inspiration TIME RESMED © Res. Med 2002
Normal Breathing Normal rounded breath RESMED © Res. Med 2002
Flow Limited Airway FLOW flattened area TIME Silent partial obstruction RESMED Flattened inspiratory flow time curve denoting partial obstruction © Res. Med 2002
Flow Limitation/Flattening Flattened breath RESMED © Res. Med 2002
Snoring n n Snoring is the noise generated by vibrations of the walls of the upper airway while breathing in and out Snoring typically occurs after flow limitation and before the development of apnea Spectrum of upper airway collapse Flow limitation > Snoring > Apnea RESMED © Res. Med 2002
Snoring Inspiratory Flow Curve FLOW Patient’s Airway TIME Noisy partial obstruction RESMED Snore superimposed on inspiratory flow- time curve © Res. Med 2002
Apnea n n Airway becomes completely occluded or severely limited = obstructive apnea Cessation of air flow / breathing for > 10 seconds n n RESMED Apneas can lead to oxygen desaturation and arousals Apnea frequency increases during REM sleep or in relation to sleeping position © Res. Med 2002
Apnea Inspiratory Flow Curve FLOW Patient’s Airway TIME Complete airway collapse RESMED Absence of flow (>10 sec ) = apnea © Res. Med 2002
RESMED © Res. Med 2002
Maximizing compliance to PAP therapy RESMED © Res. Med 2002
Maximizing compliance to PAP therapy Patient education - prior to- and post therapy n n n Short term memory loss and mild confusion n n RESMED involve family members/caregivers explanation of OSA, consequences if not treated, how treatment works, what the patient can expect use of educational tools e. g. videos and brochure trial of PAP take time and allow patients to ask questions common in sleep apnea patients need frequent reminders of the importance of treatment © Res. Med 2002
Maximizing compliance to PAP therapy Mask fit n n n n RESMED Most common reason for non-compliance Invest time to fit correctly Mask fitting videos, templates, guidelines Use mask fitting feature on Auto. Set devices Mouth leak common in stroke patients with facial droop or compromised lip seal Examine nightly leak profile from Auto. Set devices Consider full face mask Patient positioning - sleeping on side vs back © Res. Med 2002
Maximizing compliance to PAP therapy n Nasal problems (runny/stuffy/dry - or patient complains of flu like symptoms) n n n RESMED usually due to an increase in nasal resistance because of high flow rates nasal congestion results in mouth breathing can cause nasal congestion! Heated humidification usually resolves nasal problems Auto. Set devices - lower mean pressures, therefore less nasal problems © Res. Med 2002
Usage Profile RESMED Auto. Set TTM © Res. Med 2002
Treatment Profile RESMED Auto. Set T © Res. Med 2002
Interface Selection (1) Nasal Masks n n n RESMED Lessen dead space Reduce claustrophobia Minimize complications if vomiting occurs Allows expectoration and oral intake Enables patient to vocalize © Res. Med 2002
Interface Selection (2) Full Face Masks n n Offers effective treatment for mouth breathers Patients on NIPPV treatment n n n Alternative to chin straps Mouth leak n n n RESMED mouth leak “. . occurs during the majority of sleep in patients with respiratory insufficiency using nocturnal nasal ventilation” n Dries out the nasal passages Causes nasal blockage Result - ineffective therapy Significantly affects compliance, sleep efficiency © Res. Med 2002
Interface Selection (3) Other Important Factors n n n Noise Weight CO 2 washout Seal Mask Fitting n n RESMED Ease of fitting Extremely important for long term compliance Mask fitting workshops, templates, guidelines Titration mask is usually the prescribed mask © Res. Med 2002
Summary n n n RESMED SDB is very common in the general population and is associated with cardiovascular disease The most widely accepted treatment for SDB is positive airway pressure (PAP) Patients with OSA benefit from CPAP and can be managed very effectively with auto-titration therapy Patients with restrictive or obstructive lung diseases benefit from bi-level PAP Treatment of SDB with PAP is usually associated with resolution of symptoms, increased quality of life and a reduced risk of developing cardiovascular disease. © Res. Med 2002
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