Advanced Positive Airway Pressure (PAP) Treatment Modalities Nic Butkov, RPSGT Asante Sleep Center Medford, Oregon

Currently-Available PAP Modalities CPAP Bi-level PAP spontaneous (S) mode Bi-level PAP spontaneous/timed (S/T) mode Bi-level PAP timed (T) mode Bi-level PAP with pressure control (PC or PAC) mode Average Volume-Assured Pressure Support (AVAPS™) or Intelligent Volume-Assured Pressure Support (iVAPS™) Adaptive servo-ventilation (ASV) mode

Treatment Applications CPAP for upper airway obstruction Bi-level S for basic ventilatory support Bi-level S/T for ventilatory support with back-up respiratory rate Bi-level PC or PAC for ventilatory support with fixed inspiratory time AVAPS or iVAPS for ventilatory support with regulation of tidal volumes and back-up rate ASV for central sleep apnea

Basic Concepts of Bi-Level PAP Therapy Expiratory positive airway pressure (EPAP) Provides the baseline PAP level Maintains upper airway patency during expiration Prevents alveolar collapse and improves functional residual capacity (FRC) Reduces work of breathing and improves oxygenation Inspiratory positive airway pressure (IPAP) Maintains upper airway patency during inspiration Provides pressure support to augment ventilation Decreases work of inspiratory muscles

Setting the EPAP The baseline EPAP level is usually kept low (4 – 5 cwp) unless closed airway apneas are present EPAP can also be increased in select cases to help recruit the alveoli and improve oxygenation High EPAP levels may be contraindicated in some patients

Setting the IPAP for Pressure Support EPAP-IPAP span = pressure support (PS) A low EPAP-IPAP span (PS of 4 cwp or less) offers expiratory relief, but is generally insufficient for added ventilatory support For patients needing added ventilatory support, a span of 6 cwp or higher is usually required (higher PS = higher breath volumes) However, excessive PS may lead to upper airway instability and may be contraindicated for some patients

Timed Inspiration and I:E Ratio Timed inspiration (Ti) is used with some PAP modalities When using Ti, it is essential to calculate the resulting inspiratory to expiratory (I:E) ratio based on the respiratory rate For example, at a rate of 12 bpm, each breath cycle is 5 seconds in duration. An inspiratory time of 1.66 sec. with an expiratory time of 3.34 sec. delivers a 1:2 ratio

Timed Inspiration (cont.) Shorter inspiratory times are generally used for patients with obstructive lung conditions, to allow longer time for expiration Longer inspiratory times are generally used for patients with restrictive lung conditions; however, inspiratory time should never exceed the length of expiratory time

Timed Inspiration (cont.) Respironics applies Ti only to machine- delivered breaths in their ST mode ResMed applies minimum and maximum inspiratory times limits to all breaths in their S, ST, and iVAPS modes The Min Ti sets the obligatory Ti baseline The Max Ti allows for longer inspiratory times based on the patient’s own breath cycle In PC or PAC mode, fixed Ti is applied to all breaths

Setting the Ti Ti settings are based on clinical indicators, making certain that appropriate I:E ratios are maintained When applied only to machine-delivered breaths, Ti is set relative to the back-up rate When Ti is applied to all breaths, the patient’s spontaneous rate must be taken into account during all stages of sleep under all circumstances

PAP Trigger and Cycle PAP Trigger = transition from EPAP to IPAP PAP Cycle = transition from IPAP to EPAP Medium trigger and cycle sensitivities work well in most cases Higher trigger sensitivity and lower cycle sensitivity may be useful in restrictive or neuromuscular disease Higher cycle sensitivity may be useful in obstructive lung disease

Rise Time Rise time = the amount of time (measured in milliseconds) set for the PAP device to reach IPAP when a breath is triggered Generally, shorter rise times are used for obstructive lung conditions; longer rise times are used for restrictive lung conditions Rise time should be set according to efficacy of treatment and patient comfort

Mask Selection Mask Type Mask type makes a difference! Nasal mask Nasal pillows Oronasal (full-face) mask Mask type makes a difference! Changing between nasal and full-face mask may require additional PAP adjustments

Mask and Tubing Settings All PAP machines need to be set correctly for the type of mask and tubing used

Bi-Level PAP S Mode Sometimes used as a substitute for CPAP Can be used for ventilatory support in patients with COPD, neuromuscular disease and obesity hypoventilation Not appropriate for patients with Cheyne-Stokes respiration or other forms of central apnea

Basic Bi-Level S Settings EPAP IPAP Rise time Timed inspiration (minimum-maximum limits) are used on some equipment (ResMed)

Bi-Level S Mode Titration Starting pressures are typically 8/4 cwp Rationale for adjusting EPAP and IPAP EPAP is increased for closed-airway apneas (keeping the same EPAP-IPAP span) IPAP is increased for residual hypopneas, RERAs and/or snoring IPAP is further increased for added ventilatory support (if indicated)

Diagnosic study: severe hypoxemia during REM sleep

Improved O2 saturation levels and sleep architecture with bi-level PAP Settings: EPAP = 4 cwp, IPAP = 11 cwp (S mode)

Bi-Level S/T Mode S/T mode is used when a back-up rate is required Sometimes used to treat select patients with opioid induced central apnea S/T mode is generally not recommended for central apneas with Cheyne-Stokes respiration

Basic Bi-Level S/T Settings EPAP IPAP Back-up rate Timed inspiration (Ti) Fixed Ti is applied only to machine-delivered breaths (Respironics) Minimum-maximum Ti limits are applied to all breaths (ResMed) Rise time

Opioid-induced Biot’s respiration Fragmented sleep Opioid-induced Biot’s respiration

Bi-Level S/T 12/4 cwp with back-up rate of 8 bpm Sleep is partially improved Bi-Level S/T 12/4 cwp with back-up rate of 8 bpm

Bi-Level PC or PAC mode Fixed timed inspiration is applied to all breaths Ventilatory support is achieved by balancing the EPAP-IPAP span with timed inspiration Inspiratory time must be set to maintain appropriate I:E ratio relative to the patient’s respiratory rate during all stages of sleep under all circumstances PC or PAC mode is sometimes prescribed for select patients with neuromuscular disease

Basic Bi-Level PC/PAC Settings: EPAP IPAP Back-up rate Timed inspiration (applied to all breaths) Rise time

Combined effect: NMD, opioid use and upper airway obstructive component

Bi-level S/T: 15/6 cwp with back-up rate 10 bpm

PC mode: 12/6 cwp; Ti 2 sec., back-up rate 10 bpm (IE ratio = 1:2)

Adaptive Servo-Ventilation (ASV) Intended for treating central sleep apnea Not appropriate for hypoventilation syndromes Variable EPAP maintains upper airway patency Variable IPAP with back-up rate delivers pressure support Based on a recent study, ASV is contraindicated for heart failure patients with moderate-severe CSA and left ventricular ejection fraction <45%* * Serve-HF Clinical Trial

Considerations Regarding Central Apneas that are Unresponsive to CPAP (Possible Causes) Uncorrected obstructive apneas that appear ostensibly central Central apneas caused by excessive PAP levels Central apneas temporarily appearing during adjustment to PAP therapy Repetitive sleep-onset central apneas Cheyne-Stokes respiration Opioid-induced Biot’s respiration

Cheyne-Stokes Respiration vs. Biot’s Respiration Cheyne-Stokes respiration is characterized by crescendo-decrescendo breathing with central apnea or hypopnea, as often seen in patients with congestive heart failure Biot’s respiration is characterized by brief clusters of shallow breaths with central apnea or hypopnea, as typically seen in patients using opioid medications

Cheyne-Stokes respiration

Biot’s respiration

Biot’s / ataxic respiration

Basic ASV Settings: EPAP min EPAP max PS min PS max Respironics also provides selection of auto vs. manual back-up rate, rise time and maximum pressure limit

Diagnostic study – central sleep apnea with obstructive component NREM sleep with arousals Diagnostic study – central sleep apnea with obstructive component

ASV titration (EPAP - 5; min PS - 0; max PS - 10; back-up rate - auto) Transitional sleep ASV titration (EPAP - 5; min PS - 0; max PS - 10; back-up rate - auto)

ASV titration continued (same settings) Sleep is becoming more consolidated ASV titration continued (same settings)

ASV titration is complete (same settings) Quiet NREM sleep ASV titration is complete (same settings)

Volume-Assured Pressure Support (AVAPS or iVAPS) Can be used for neuromuscular disease, obesity hypoventilation, restrictive or obstructive lung disease, or for select patients with opioid-induced central apnea Uses a variable range of pressure support to maintain pre-set target tidal volumes

Tidal Volumes Tidal volume = volume of air moved in and out of the lungs with each breath In healthy adults, normal tidal volumes are in the range of approximately 500 milliliters per breath, or 7 milliliters per kilogram of body weight When using AVAPS or IVAPS, target tidal volumes are generally calculated based on ideal body weight relative to the patient’s height (starting values of 6 - 8 ml/kg are usually applied, or as directed by the physician)

AVAPS Settings: S, ST or PC mode Target tidal volume Back-up rate (ST and PC modes) EPAP Minimum IPAP Maximum IPAP Timed inspiration Applied only to delivered breaths in ST mode Applied to all breaths in PC mode Rise time

iVAPS Settings Patient height Target respiratory rate Target alveolar ventilation EPAP Minimum pressure support Maximum pressure support Minimum Ti Maximum Ti Trigger Sensitivity Cycle Sensitivity Rise time

Evaluating the Respiratory Data The PAP flow and pressure channels should be checked for synchrony with the respiratory effort channels Asynchronous waveforms may be caused by excessive mask leaks, mouth breathing, incorrect inspiratory time settings, or inadequate trigger and/or cycle sensitivity settings

PAP flow waveforms are synchronous with the chest and abdomen waveforms

PAP flow waveforms are asynchronous with the chest and abdomen waveforms

CPAP of 11 cwp with EPR of 3 – synchronous pressure and flow signals

Asynchronous pressure and flow signals – sporadic pressure support

Asynchronous pressure and flow signals with excessive PAP levels

Fine-Tuning the Settings Strategies for improving PAP flow synchrony: Check and correct mask leaks Consider the possibility that the PAP levels might be too high Check for appropriate inspiratory time values (if applicable) Check for appropriate trigger and/or cycle sensitivity settings (if applicable) Try manipulating the rise time setting (extending the rise time can sometimes help prevent mask leaks during inspiration)

Evaluating the Titration Was the appropriate PAP modality selected? What type of mask was used and why? Was the machine set correctly for type of mask and tubing used? Was baseline EPAP increased and if so, why? If variable EPAP was used, were the settings appropriate? How much pressure support was applied and was it appropriate? If variable pressure support was used, was the range sufficient?

Evaluating the Titration (cont.) What was the patient’s respiratory rate during wakefulness, during NREM sleep and during REM sleep? Was timed inspiration applied and was it appropriate relative to the patient’s respiratory rate? Was timed inspiration applied only to delivered breaths or to all breaths? If minimum-maximum inspiratory time limits were applied, were the settings appropriate?

Evaluating the Titration (cont.) If trigger and cycle sensitivity settings were adjusted, were they appropriate and effective? How was the rise time selected and was it appropriate and comfortable for the patient? Did the PAP flow waveforms appear synchronous with the respiratory effort waveforms? What were the tidal volumes readings during the study (NREM and REM sleep in all body positions)?

Evaluating the Titration (cont.) What were the O2 saturation readings during the study (NREM and REM sleep in all body positions)? What were the recorded leak values during the study (NREM and REM sleep in all body positions)? Was the head of the bed elevated during the study and if so, did it replicate the patient’s home environment? Was supplemental oxygen used during the study and was it necessary?

Evaluating the Titration (cont.) Was there any evidence of residual upper airway obstruction or resistance (NREM and REM sleep in all body positions)? Were open-airway central apneas and hypopneas adequately resolved with treatment? Was the patient breathing quietly and effortlessly (based on direct observation)? Was the patient’s sleep quality improved? Did the patient tolerate the treatment well? Did the patient feel better after treatment?

Summary EPAP and IPAP should be sufficient, but not excessive All PAP settings (such as back-up rates, Ti, etc.) must be verified as appropriate for the patient Efficacy of treatment involves maintaining upper airway patency, providing adequate ventilatory support, and improving quality of sleep