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Central Sleep Apnea Syndromes
6th Annual ConferenceNorthwest Ohio Southeast Michigan Sleep SocietyMay 1, 2009
Navin K Jain, MD
CENTRAL SLEEP APNEA
“ period of at least 10 seconds without airflow, during which no ventilatory effort is evident”
Normal Control of Breathing
Automatic / Metabolic Chemoreceptors (carotid body for hypoxia and carotid body and
medullary receptors for hypercapnia and H ion) Intrapulmonary receptors – vagus mediated Brainstem processes Keep ventilation regular and match to metabolic demands
Afferent Information from chest wall and respiratory muscles Behavioral / Volitional – under voluntary control Wakefulness stimulus – increased ventilation in awake state
(ventilation persist during wakefulness in absence of metabolic mechanisms)
Control of Breathing at Sleep/Wake Transition to Sleep
Loss of wakefulness stimulus and behavioral influences Muscle activity and chemoreceptor sensitivity is reduced
Apnea threshold Stable sleep changes – sleep specific CO2 set point Transition to Wake - important to restore gas
exchange; may cause central apnea: Arousal threshold Ventilatory Response to arousal
Control Of Breathing in Sleep Non REM Sleep
Metabolic Control – input from chemoreceptors and vagal intrapulmonary receptors (oxygen administration in hypoxic individuals reduces ventilation and may prolong apneas in some individuals; hypocapnic alkalosis also reduces ventilation)
Response of chemoreceptors are somewhat reduced in Non REM sleep but still well maintained and maintains rhythmic ventilation during sleep
REM Sleep – further reduction in responsiveness of chemoreceptors
Central Sleep Apnea
Lack of drive to breathe during sleep Lack of respiratory efforts during cessation of airflow Insufficient or absent ventilation leading to compromised gas
exchange May lead to frequent nighttime awakenings leading to excessive
daytime sleepiness and increased risk of adverse CV outcomes
Most patients have overlap of OSA and CSA CSA Syndrome is considered primary diagnosis when >50% of
apneas are scored as central in origin
CSA: Classification
Central Sleep Apnea High Altitude Periodic Breathing Idiopathic CSA Narcotic Induced Central Apnea
Cheyne Stokes Breathing (CSB) Obesity Hypoventilation Syndrome (OHS)
(Hypercapneic CSA) Complex Sleep Apnea
CSA Syndrome
Hypercapnic – impaired ventilatory output during wakefulness (worsens is sleep as wakefulness stimulus is removed) Impaired Central Drive Impaired Respiratory Motor Control
Nonhypercapnic Cheyne Stokes Breathing Idiopathic CSA
Hypercapnic CSA: Impaired Central Drive Lesions of brain stem – tumors, trauma
induced lesions Congenital Central Hypoventilation
Syndrome (Ondine’s curse) Long term use of Opioids – prolonged
periods of hypoventilation with marked hypoxemia and repetitive central apneas; dose dependent effects
Obesity Hypoventilation Syndrome (OHS)
CSA: Neurologic causes
Disorders of autonomic system Autonomic dysfunction - Shy Drager Syndrome Familial Dysautonomia Diabetes Mellitus
Damage to Brain Stem (respiratory centers) Post Polio syndrome Tumor, Infection, Hemorrhage, encephalitis
Interruption of Neural pathways from medullary respiratory centers to ventilatory muscles Cervical cordotomy
Chronic Opioid use
Becoming more common for chronic pain (even non malignant disorders)
Most experts believe – respiratory tolerance develops and respiratory depression is absent or mild
During wakefulness, chronic respiratory acidosis is absent or mild
While sleeping, 30-90% patients will have sleep apnea (central or obstructive) – may contribute to mortality
Obesity Hypoventilation Syndrome Obesity – BMI > 35 Alveolar Hypoventilation (PaCO2 >45 mm Hg) while awake Hypoventilation worsens during non-REM sleep and further
during REM sleep Other causes of hypoventilation have been ruled out
COPD, Interstitial Lung Disease Chest Wall Disease – Kyphoscoliosis Hypothyroidism Heart failure Diaphragm Paralysis
Hypercapnic CSA: Impaired Respiratory Motor Control Neuromuscular Disorders
Myasthenia Gravis ALS Post Polio Syndrome Myopathies
Chest wall syndromes Kyphoscoliosis
Nonhypercapnic CSA
CSB Idiopathic CSA
Cheyne-Stokes Breathing (CSB)
Cyclic crescendo-decrescendo respiratory effort and airflow during wakefulness and sleep, without upper airway obstruction
Idiopathic CSA
Do not show CSB / transition apnea with normocapnia
May occur as distinct events or repetitive cyclical pattern
Duration of cycle – usually 20-40 seconds; less severe O2 desaturations
Mainly in stage N1 and N2 sleep Arousals at termination of apnea May complain of insomnia or hypersomnia Usually have elevated hypercapnic ventilatory
response
High Altitude Periodic Breathing Most healthy individuals will have periodic
breathing on high altitude ascent provide ascent causes significant alveolar hypoxia
Factors affecting CSA severity Hypoxia
Any hypoxia tends to worsen CSA severity More severe hypoxia seen in OHS; mild in idiopathic CSA
and OHS Hypoxia may impair respiratory sensory feedback
Upper Airway Anatomy Narrow upper airway can collapse in central apnea (as it
depends on neuronal input) Treatment of OSA with PAP may cause hypocapnia in
patients and may cause treatment emergent CSA by causing hypercapnia (Complex Sleep Apnea)
Cheyne Stokes Breathing (CSB)
Cheyne-Stokes Breathing (CSB)
Cyclic crescendo-decrescendo respiratory effort and airflow during wakefulness and sleep, without upper airway obstruction
If decrescendo effort is accompanied by apnea during sleep, it is a type of central sleep apnea syndrome
Mainly seen is stage N1 and N2 sleep Cycle time – 60-90 seconds (longer than other forms of CSA);
correlation with severity of HF Arousal typically occurs mid cycle at peak of ventilatory effort Most commonly seen in patients with CHF and LV systolic dysfunction Often co-exist with OSA (together may be classified as Sleep
Disordered Breathing)
CSB: Pathogenesis
Uncertain Seen as series of events
Patients are hypocapnic to begin with, so to correct hypocapnia, respiratory center initiates an apnea; pCO2 begins to rise.
Duration from beginning of apnea until respiratory center detects increasing PaCO2 is prolonged due to increased circulatory time
When respiratory center terminates apnea, it is already hypercapnia
Hypercapnia causes hyperpnea which causes hypocapnia NET EFFECT – oscillation of ventilation between apnea and
hyperpnea Elimination of hypocapnia with inhaled CO2, CPAP or O2 can
attenuate CSB
Factors contributing to CSB
High ventilatory drive Minimal difference between apnea threshold
and sleeping eucapnic PaCO2 Long circulation time Impaired cerebrovascular reactivity to CO2 Increase pulmonary capillary wedge pressure
may stimulate J receptors in lung causing apnea and resultant hyperventilation
Sleep Disordered Breathing (SDB) in Heart Failure SDB may be seen in ~50% all patients with heart
failure and ~70% patients with heart failure who are referred to sleep laboratory
Can be seen among patients whose heart failure is optimally managed
CSB may be more common than OSA in patients with heart failure
CSB more common among men, elderly, atrial fibrillation, and hypocapnia
OSA more common among older individuals and increasing BMI
CSB: Effects
Intermittent hypoxia – increased sympathetic drive causing arhythmia and worsening of HF
Arousals – induce adrenergic surges Impair systolic and diastolic function Extremely negative intrapleural pressure with hyperpnea
increase ventricular transmural wall stress and afterload CSB in patients with heart failure is associated with higher
cardiac mortality Clinically
Poor sleep quality – sleepiness in daytime Symptoms of worsening heart failure – dyspnea, edema Paroxysmal nocturnal dyspnea (due to hyperpnea) Nocturnal angina, recurrent arrhythmia
CSB : Treatment
Management of CHF Supplemental Oxygen Acetazolamide Theophylline Pacemaker Heart Transplantation PAP therapy
Narcotic Induced CSA
Chronic Opioid use : CSA / CompSA
While sleeping, 30-90% patients on chronic opioids will have sleep apnea (central or obstructive) – may contribute to mortality
Acute uses – case report Chest 2008 (nightly dose) low AHI high sleep efficiency Disproportionate symptoms (excess daytime
sleepiness
CSA in Chronic Opioid Users
Develop combination of obstructive and central apnea events (pathogenesis – unknown) Central events mainly in Non REM sleep With PAP therapy, on CPAP obstructive events may be
corrected and central events persist When compared to age, gender, and BMI matched
controls, higher AHI is due to central events Dose relationship noted with AHI and dose of opioid
Central Apnea events Periods of apnea and hyperepnea (Biot’s respiration) Breaths at end of apnea are abrupt and not gradual Irregular; erratic pattern of respiratory rate and tidal volume
CSA in Chronic Opioid Users
Central Apnea events Periods of apnea and hyperepnea (Biot’s respiration) Breaths at end of apnea are abrupt and not gradual Irregular; erratic pattern of respiratory rate and tidal
volume
Biot’s Respiration
Narcotic Induced CSA: Treatment Minimize dose of Narcotics PAP therapy
CPAP – alone not effective Usually require APSSV
Obesity Hypoventilation Syndrome (OHS)
Pickwick Papers
Obesity Hypoventilation Syndrome Obesity – BMI > 35 Alveolar Hypoventilation (PaCO2 >45 mm Hg) Hypoventilation worsens during non-REM sleep and
further during REM sleep Other causes of hypoventilation have been ruled out
COPD, Interstitial Lung Disease Chest Wall Disease – Kyphoscoliosis Hypothyroidism Heart failure Diaphragm Paralysis
OHS: clinical features
Symptoms similar to OSA Loud snoring, periods of choking in sleep, excessive sleepiness in daytime,
fatigue Dyspnea on exertion BMI >35 kg/m2 May heave features of Right Heart Failure
Rales, hepatomegaly, edema Hypercapnia – PaCO2>45 mm Hg during wakefulness Hypoxic – PaO2 <70 mm Hg but have normal alveolar-arterial gradient
if no associated heart or lung disease Elevated hematocrit EKG, ECHO – features of RVH, Pulmonary HTN PFT – restrictive ventilatory defect Often have coexisting OSA
OHS: Pathogenesis
Obesity Related Physiologic abnormalities OSA Increased work of breathing – due to reduced lung compliance and
increased effort to move ribs and diaphragm Respiratory Muscle Impairment - Depressed Central Ventilatory Drive – reduced response to
chemostimuli – hypoxia and hypercapnia (it may be effect of OHS rather than cause)
V/Q mismatching – poor ventilation of lower lobes and increased perfusion to lower lobes
Diminished effects of neurohumoral modulators (leptin) due to reduce levels or resistance
Weight Loss alone can cause decrease in PaCO2 during wakefulness in these patients
OHS and sleep study
Oxygen desaturation during sleep Occur for longer periods than in patients who
have OSA alone Most patients have associated OSA AHI severity is not associated with likelihood
of coexisting OHS but severe oxygen desaturation is associated with coexisting OHS
OHS: Treatment
Weight Loss Respiratory Stimulants
Progesterone PAP therapy Oxygen Phlebotomy
Treatment Emergent CSA
Complex Sleep Apnea (CompSA)
Complex Sleep Apnea (CompSA)
Described by Morgenthaler; Sleep2006 29:1203-09
Treatment emergent central sleep apnea Persistence or emergence of central apneas
or hypopneas upon exposure to CPAP or an E0470 device when obstructive events have disappeared
Controversial – is it really a disease
CompSA: A Disease
Patients have anatomic and physiologic vulnerability causing OSA and a central breathing control instability
Seen more among men Less sleep maintenance insomnia complaint Higher likelihood of CHF or ischemic heart disease Is it transient or persist if treated with CPAP alone
CompSA: Not a Disease
Transient and disappear with CPAP therapy in most patients
Relief of upper airway obstruction may cause change in CO2 excretion (so PaCO2 falls below apnea threshold)
Over titration Activation of lung stretch receptors inhibits central
respiratory motor input Washout of CO2 from anatomic dead space
Increased transitions from sleep to wake as getting used to PAP – CPAP initiation may worsen sleep quality
BPAP Titration
BPAP - Timed
Adapt PS Servo Ventilation
PAP therapy
Continuous PAP (CPAP) Useful in OSA Useful in CSA with systolic heart failure
Bi-level PAP (BPAP) Bi-level PAP with timed mode (BPAP S/T) Adaptive Pressure Support Servo Ventilation
(APSSV) Used in patients with CSA, treatment emergent
CSA, CSB
APSSV
Expiratory Pressure is set to eliminate obstructive apneas
Inspiratory support (variable) above expiratory pressure – provided by breath-breath analysis
Back Up Rate – aborts any impending central apnea Some times may not work as well in patients with
chronic opioid therapy (may not regulate irregular breathing)
Diagnosis of CSA
No screening tool – like apnea link Main test - Polysomnogram