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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

15. 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

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

17. 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)

18. Diagnosic study: severe hypoxemia during REM sleep

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

20. 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

21. 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

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

23. 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

24. 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

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

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

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

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

29. 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

30. 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

31. 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

32. Cheyne-Stokes respiration

33. Biot’s respiration

34. Biot’s / ataxic respiration

35. 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

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

37. 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)

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

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

40. 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

41. 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 ml/kg are usually applied, or as directed by the physician)

42. 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

43. 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

44. 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

45. PAP flow waveforms are synchronous with the chest and abdomen waveforms

46. PAP flow waveforms are asynchronous with the chest and abdomen waveforms

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

48. Asynchronous pressure and flow signals – sporadic pressure support

49. Asynchronous pressure and flow signals with excessive PAP levels

50. 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)

51. 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?

52. 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?

53. 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)?

54. 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?

55. 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?

56. 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