A device able to provide less positive airway pressure (PAP) for the entire duration of inspiration and roughly half the duration of expiration, designated KPAP, is being developed by SleepRes for the treatment of obstructive sleep apnea (OSA). In prior studies, the administration of higher inspiratory than expiratory PAP did not substantially increase treatment efficacy or adherence to continuous PAP (CPAP), which remains low. In our recent investigation, we demonstrated that the addition of a resistor to the CPAP circuit to reduce inspiratory PAP increased subjective comfort. In another study, we showed that KPAP improved subjective comfort during wakefulness vs. fixed CPAP, while maintaining treatment efficacy. The present study, KPAP Adherence 1, is a randomized, crossover study designed to examine whether KPAP can improve adherence over APAP as an at home treatment for OSA.

The KPAP Adherence 1 is a randomized, crossover study in which the adherence to therapy will be compared between KPAP and standard APAP. Participants will be chosen from a pool of patients who are PAP-naïve and who have received either a PSG (in-lab polysomnogram), split-night study (in-lab PSG and pressure titration) or home sleep study (HST) within the previous 3 months.

Upon signing an informed consent, participants will be randomly assigned to start on either the KPAP (supplied by a SleepRes device) or the APAP (supplied by a ResMed device) arm when they arrive at the office. Each participant will then be given their new equipment and will be trained in proper use of the device assigned for the first treatment arm. The device will be used at home, nightly, for 4 weeks. Afterward, they will return to the office for their second visit. They will then be given the other device-along with the appropriate explanation on how to use it-that they will use on their second treatment arm. Subsequently, they will undergo a washout period of 1 week where no therapy will be used. Following the washout period, they will initiate another 4-week usage with the second therapy device. At the end of the second 4-week period, participants will return to the office for their third visit.

In both the APAP and KPAP arms, participants will have their therapy set to 5-20 cmH2O for one week. The pressure range will then be narrowed to ± 2 cmH2O around their 95% pressure level as assessed during the first week. This same pressure range will be used during the second arm for each patient.

During the KPAP arm, participants will be set to a double Comfort Setting drop according to the following scheme. This drop schedule will be implemented while the KPAP device is operating with automatic pressure adjustment.

Pset Drop 1 Drop 2 5.0 - 5.9 0 0 6.0 - 6.9 1 0 7.0 - 7.9 2 0 8.0 - 8.9 2 1 9.0 - 9.9 2 2 10.0 - 20.0 2 3

Phone calls to encourage use and assess adherence and side effects will be made at different time points during both treatment arms. Subjects using the device less than an average of 5 hours per night during the first week will be contacted on a more regular basis (weekly until 5 hour per night use is achieved) to address any problems and encourage use. If participants discontinue the use of the device during the home use period, they will still be encouraged to return for all testing per protocol. If a patient refuses to come in for further testing, they will be considered a lost to follow up and excluded from efficacy analysis.

• 1 Day Phone Call (+2 days)
• 7 Day Phone Call (+/- 3 days)
• 14 Day Phone Call (+/- 3 days)
• 21 Day Phone Call (+/- 3 days) to remind participants and schedule the office visit and device return on day 28
• Equipment Return

After each arm, the patient will return to the office for the after-treatment visit (Visit 2 and Visit 3) to record the following:

• Adverse Event Assessment
• PROMIS Fatigue
• Epworth Sleepiness Scale (ESS)
• Functional Outcomes of Sleep Questionnaire (FOSQ)
• Short Form 36 (SF36)
• Comfort and Satisfaction, per Visual analog Scale (VAS)
• Nightly adherence recording

Data collected from the therapy device will include the following:

• Usage averaged over the 4-week period and nightly
• Leak averaged over the 4-week period and nightly
• P95 averaged over the 4-week period and nightly
• Sleep events averaged over the 4-week period and nightly

Inclusion Criteria:

1. AHI > 10 on a previous PSG or HST (hypopneas requiring 4% desaturation).
2. Central apneas < 25% of events
3. PLM (Periodic Limb Movements) arousal index < 15

Exclusion Criteria:

1. A female of child-bearing potential that is pregnant or intends to become pregnant.
2. Any unstable or severe medical condition of any organ system including congestive heart failure, COPD, renal failure, neuromuscular disease, etc., or at the discretion of the site Principal Investigator (PI).
3. Taking medication that may affect sleep, sleepiness, or alertness including hypnotics, sedatives, alerting agents, stimulants, anticonvulsants, etc.
4. The presence of any other sleep disorder (insomnia, periodic limb movement disorder, etc).
5. Prior therapy or treatment for OSA.
6. Chronic oxygen therapy.
7. Excessive alcohol consumption (>14 drinks/week).
8. The use of any illegal drug(s).
9. Any condition that in the investigator's opinion would present an unreasonable risk to the participant, or which would interfere with their participation in the study or confound study interpretation.

Participants will not be told what therapy they will be using in either arm, and since they are naive to PAP therapy, they would be more blinded than adherent patients.