Complex Sleep Apnea: Definition Complex Sleep Apnea is a form of sleep apnea in which central apneas persist or emerge (CAI >5) during attempts to treat obstructive events with nCPAP or Bilevel PAP.
Patient Characteristics 1. > 90% are Male (ref 14) 2. BMI is slightly less than average OSA patient (ref 16) 3. ? Higher incidence of ischemic heart disease or CHF (ref 15) 4. Slight predominance in atrial fibrillation, opiate use (ref 1 and 2) 5. ? Elevated nasal resistance (ref4)
Natural History of Complex Apnea Prevalence of syndrome- 5.7 to 20%. In 78%- 92% of pts, CAs resolve within months in CPAP adherent patients. Of pts without Com SA on initial CPAP titration, 4% developed it on 3 mo f/u !! Ref 1 and 2
Polysomnographic Characteristics May have evidence of central events on baseline PSG (CAI >5) (ref 1) Events more common in nREM sleep (ref 16) Elevated Arousal Index (ref 16) On F/U CPAP titration in 2-3 months, persistent CA more likely if severe OSA or CSA >5 (ref 1)
Clinical Impact of nCPAP in “Complex Apnea” 1.Residual or Worsening Symptoms (Fatigue, EDS, Depression) Secondary to Arousals/Disrupted Sleep 2.Higher Incidence of “CPAP Difficulty” (ref18) 3. ↑ Sympathetic Activity (ref 18)
A.Behavioral B.Metabolic 1.Chemoreceptors a.Carotid Bodies b.Medulla 44 36 Eupnea Apnea Threshold CO2 Reserve Controls of Breathing: AWAKE Y axis = pCO2 o xxx o oo o
Controls of Breathing - Sleep 38 Apnea Threshold REM nREM 1.Loss of Behavioral Control 2.Narrow CO2 Reserve in nREM 3.Hypoxia Further Reduces pCO2 4.Metabolic Acidosis Widens CO2 Reserve Y axis = pCO2 CO2 Reserve Apnea Threshold CO2 Reserve 39 OoOo oo job
Controls of Breathing During Sleep - CHF 1. Pulmonary Afferent Receptors pCO2 Apnea Threshold 2. Loop Gain A. Increased Response to pCO2 B. Increased Lung to Peripheral Chemoreceptor Circulation Time xxx o ooo
Controls of Breathing During Sleep Effects of nCPAP/Bilevel PAP 1. Effect of Opening Airway - ↑ Minute Ventilation (Increases plant gain) 2. Fragmented Sleep with Arousal – (discomfort/ elevated nasal resistance) 3. PAP induced distention of stretch receptors (Hering Breuer inflation reflex) pCO2 Apnea Threshold CO2 Reserve
Diagnostic Challenges 1.Increasing number of patients not undergoing CPAP titration 2.Autotitrating PAP devices vary in ability to warn clinician of emerging central apnea 3.Failure to diagnose Complex Apnea may lead to poor compliance and abandonment of PAP therapy. 4.Overtitration may result in inappropriate dx.
Therapy for Complex Apnea 1.Adaptive Servo Ventilation 2.nCPAP Close F/U, permissive flow limitation/ additional dead space 3.Supplemental 02 4.Medications benzodiazepines/ acetazolamide
Adaptive Servo Ventilation (ASV) Airway Pressure Device devised for Treatment of CSA/CSR as well as Complex Apnea Automatic Pressure Support (Dynamically Calculated) to result in Consistent Tidal Volume Automatic Backup Rate (Calculated) Multiple Studies show Effective Clinical Results in Treating Complex Apnea
Respironics BiPAP Auto SV Responds to Peak Flow and Adjusts Pressure Support Accordingly Manufacturers Suggestion for Settings: Set EPAP or EPAP min Set PS 2-15 Set IPAP max = 25 Rate = auto
Breath to Breath Pressure Support Backup Breath Stabilization of Breathing BiPAP Auto SV BiPAP Auto SV
Res Med ♠ VPAP Adapt SV ♠ Algorithm Directed at Measuring “Baseline” TV and Respiratory Rate ♠ Can Titrate for EPAP (EEP) or use “Default Setting” of 5 cm ♠ IPAP Suggestions: Set Min PS = 3 cm Set Max PS = 10 cm
The VPAP Adapt SV Response VPAP Adapt SV (ASV mode on) Airflow HYPOPNEA APNEA Adapt SV responds to apnea by increasing support ( Apnea converted to a hypopnea & breathing quickly normalized by VPAP Adapt SV)
CSA/CSR Returns Without Treatment VPAP Adapt SV Airflow ASV mode turned off (CSA/CSR rapidly returns) Off
Comparison VPAP Adapt ASV (n=35) Avg use 5.0 Change ESS -2.5 % nights > 4 h 67 CMS compliant % 34 BIPAP Auto ASV (n=41) 6.0 -4 73.5 51 Reference 3
Therapeutic Challenges 1.Adaptive Servo Ventilation costly 2.nCPAP may eventually be adequate therapy. 3.Other therapies not well studied.
Conclusions/ Suggestions Clinicians caring for all OSA pts need proper training/ education given prevalence and natural history of Complex SA. Difficult to predict patients who will develop the syndrome. Prevalence of the syndrome highlights importance of CPAP titration study in OSA patients.
Conclusions/ Suggestions (cont) Treatment decision generally pertains to ? ASV vs close f/u on CPAP Insurance carriers may impact on these decisions Suggest confirming emergent CAs prior to ASV titration Consider 02 and pharmacologic agents Need to consider best therapy for pt, but sensitive to costs (CPAP titration/ ASV)
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