GENERAL SESSION MATERIALS Sunday, June 4, 2017 © American Association of Sleep Technologists 1 AAST 39th Annual Meeting Sunday, June 4 – Tuesday, June 6, 2017 This section of the course book contains materials to be presented in general sessions on Sunday, June 4, 2017. THIS COURSE BOOK IS ONLY INTENDED FOR REVIEW BY THE INDIVIDUAL WHO ATTENDED THE COURSE. PHOTOCOPYING AND DISTRIBUTION TO OTHERS IS PROHIBITED. © American Association of Sleep Technologists 2 © American Association of Sleep Technologists 3 Can we use physiology to understand and treat obstructive sleep apnea? Exploring the Possibility of Performing Research in Your Sleep Center Robert L. Owens, MD Scott A. Sands, PhD University of California San Diego Brigham and Women’s Hospital and [email protected] Harvard Medical School [email protected] © American Association of Sleep Technologists 4 The Big Ideas • Is all OSA the same? • Are two people with the same AHI the same? • If we knew the underlying cause of OSA, could we treat people differently? • Can we do all this in the clinic? © American Association of Sleep Technologists 5 Outline • Why might different people get OSA? • Can we measure the causes in an individual? • Is that useful? © American Association of Sleep Technologists 6 What happens when you fall asleep: normal Wake Sleep Ventilation Ventilatory Demand Time © American Association of Sleep Technologists 7 What happens when you fall asleep: normal or OSA Wake Sleep Ventilation Ventilatory Ventilation ≠ Demand Demand Because of poor anatomy Time © American Association of Sleep Technologists 8 What happens when you fall asleep: normal or OSA Hypoventilation leads to increased ventilatory demand, which will activate upper airway Wake Sleep muscles to improve Ventilation ventilation. Ventilatory But, muscle recruitment and Demand improvement in Good muscle response achieves ventilation is variable. acceptable ventilation Time © American Association of Sleep Technologists 9 What happens when you fall asleep: OSA Hypoventilation leads to increased ventilatory demand, which will activate upper airway Wake Sleep muscles to improve Ventilation ventilation. Ventilatory But, muscle recruitment and Demand improvement in Poor muscle response does not ventilation is variable. achieve acceptable ventilation Time © American Association of Sleep Technologists 10 What happens when you fall asleep: OSA Wake Sleep Wake up Arousal Ventilation Threshold Ventilatory Demand Poor muscle response does not achieve acceptable ventilation and the respiratory arousal threshold is crossed Time © American Association of Sleep Technologists 11 What happens when you fall asleep: OSA Wake Sleep Wake up Arousal Ventilation Threshold Loop gain Ventilatory Demand How quickly the ventilatory demand increases for a change in ventilation is the loop gain of the system Time © American Association of Sleep Technologists 12 What happens when you fall asleep: OSA Wake Sleep Wake up Arousal Ventilation Threshold Ventilatory Demand Time This person has OSA – with sleep they hypoventilate, and wake themselves up due to: Anatomy, upper airway muscles, arousal threshold, and loop gain © American Association of Sleep Technologists 13 Better muscles can prevent OSA Wake Sleep Arousal Ventilation Threshold Ventilatory Demand For same anatomy, better muscles can lead to stable flow limited breathing, no arousal Time © American Association of Sleep Technologists 14 ↑ arousal threshold may prevent OSA Arousal Wake Sleep Threshold Ventilation Ventilatory Demand Similarly, with same anatomy and muscle response, a higher arousal threshold may allow respiratory drive to increase enough to recruit muscles sufficiently to sustain ventilation. Time © American Association of Sleep Technologists 15 Decreased loop gain can help, too Wake Sleep Arousal Ventilation Threshold Ventilatory Demand Similarly, a lower loop gain may prevent ventilatory demand from rising above the arousal threshold. Time © American Association of Sleep Technologists 16 Pathogenesis of sleep apnea Poor upper airway High loop gain muscle response Small, collapsible Low arousal upper airway threshold Obstructive Sleep Apnea © American Association of Sleep Technologists 17 Outline • Why might different people get OSA? – Anatomy, but also upper airway muscles, arousal threshold, control of breathing • Can we measure the causes in an individual? • Is that useful? © American Association of Sleep Technologists 18 Can we measure the response to hypoventilation during sleep? Wake Sleep Ventilation Ventilatory Demand Time © American Association of Sleep Technologists 19 Yes, by letting the airway collapse 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 © American Association of Sleep Technologists 20 Measuring anatomy 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 8 6 Eupnea Ventilation 4 (L/min) 2 Anatomy 0 50 100 150 200 250 Time (seconds) With repeated drops, we can measure how much the upper airway is open at different pressures, or at atmospheric pressure (0cmH2O) © American Association of Sleep Technologists 21 Measuring muscle response 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 8 ? 6 Eupnea Ventilation 4 (L/min) 2 UA muscle response Passive UA 0 50 100 150 200 250 Time (seconds) With hypoventilation, ventilatory demand will increase an unknown amount, and some muscle recruitment will occur © American Association of Sleep Technologists 22 Measuring loop gain 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 Obstruction 0 removed, ventilation 8 again matches ventilatory drive 6 Eupnea Ventilation 4 (L/min) 2 UA gain = muscle response/ventilation deficit Passive UA 0 50 100 150 200 250 Time (seconds) Return to holding pressure opens upper airway and reveals ventilatory demand © American Association of Sleep Technologists 23 Measuring loop gain 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 Ventilatory Drive 8 6 Eupnea Ventilation 4 (L/min) 2 UA gain = muscle response/ventilation deficit Passive UA 0 50 100 150 200 250 Time (seconds) With knowledge of the ventilatory drive, can calculate loop gain of the system, and upper airway gain © American Association of Sleep Technologists 24 Measuring loop gain 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 8 6 Eupnea Response LG= Ventilation 4 Disturbance (L/min) 2 Passive UA 0 50 100 150 200 250 Time (seconds) With knowledge of the ventilatory drive, can calculate loop gain of the system, and upper airway gain © American Association of Sleep Technologists 25 Measuring arousal threshold 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 8 ? 6 Eupnea Ventilation 4 (L/min) X 2 Passive UA 0 50 100 150 200 250 Time (seconds) Some CPAP drops, the ventilation will be so low, that the ventilatory drive gets so high that you have an arousal. © American Association of Sleep Technologists 26 Measuring arousal threshold 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 8 6 Eupnea √ Response LG= = arousal threshold Ventilation 4 Disturbance√ (L/min) X 2 Passive UA 0 50 100 150 200 250 Time (seconds) Use loop gain to predict ventilatory drive at this point = AT © American Association of Sleep Technologists 27 Measuring the traits 15 CPAP Therapeutic 10 level pressure (cmH2O) 5 0 Ventilatory Drive 8 6 Eupnea Response LG= Ventilation 4 Disturbance (L/min) 2 UA gain = muscle response/ventilation deficit Passive UA 0 50 100 150 200 250 Time (seconds) Wellman JAP 2011 Wellman JAP 2013 © American Association of Sleep Technologists 28 Outline • Why might different people get OSA? – Anatomy, but also upper airway muscles, arousal threshold, control of breathing • Can we measure the causes in an individual? – Yes – during a research study that mimics OSA • Is that useful? © American Association of Sleep Technologists 29 N = 75 subjects 2013 © American Association of Sleep Technologists 30 As expected, anatomy worse in those with OSA AHI (OSA Severity) Worse Anatomy Better Anatomy © American Association of Sleep Technologists 31 But no difference in muscle responsiveness… Controls OSA © American Association of Sleep Technologists 32 Or Loop Gain between controls and those with OSA © American Association of Sleep Technologists 33 And Arousal Threshold goes the wrong way?! Harder to wake up (Protective??) Controls OSA © American Association of Sleep Technologists 34 Pathogenesis of sleep apnea Poor upper airway High loop gain muscle response Small, collapsible Low arousal upper airway threshold So is this true? Obstructive Sleep Apnea © American Association of Sleep Technologists 35 A new model that includes Effect Modification Upper airway passive anatomy Exposure Open Closed Effect modifiers No OSA OSA Outcome (High LG – CSA?) (Low AT – insomnia?) © American Association of Sleep Technologists 36 Non anatomical traits are important in some people Upper airway passive anatomy Exposure Vulnerable Anatomy Open Closed Loop gain Arousal threshold Effect Upper airway gain modifiers No OSA OSA Outcome © American Association of Sleep Technologists 37 Anatomy is important in everyone AHI (OSA Severity) Always have OSA Worse Anatomy Vulnerable anatomy – could go either way Never have OSA Better Anatomy © American Association of Sleep Technologists 38 Loop gain is important if you have vulnerable anatomy LOW LG HIGH LG In this anatomically vulnerable group of patients, whether you have OSA is dependent on LG © American Association of Sleep Technologists 39 Muscle responsiveness is important if you have vulnerable anatomy Good muscles (no sleep apnea) Bad muscles (OSA) No difference in slope, until you get to vulnerable