Evaluation of Adherence and Therapeutic Effectiveness of BiPAP With Bi-Flex Versus CPAP in Children With Obstructive Sleep Apnea

STUDY RATIONALE The obstructive sleep apnea syndrome (OSAS) affects approximately 2% of children and results in significant morbidity. Continuous positive airway pressure (CPAP) is the standard therapy for children who fail tonsillectomy and adenoidectomy, or for those in whom surgery is not indicated. However, CPAP is uncomfortable and is often not tolerated by children. Thus, a more comfortable technology that would enhance adherence would be highly desirable. This proposal aims to compare a new technology, Bi-Flex, to standard CPAP therapy.

Bilevel positive airway pressure (BiPAP): Whereas conventional CPAP therapy delivers a constant, steady pressure during inspiration and expiration, BiPAP therapy is intended to respond to both inspiration and expiration by the patient and to deliver a set amount of pressure when the patient begins spontaneous inhalation, and decreasing pressure when exhalation begins. Exhaling against lower pressure is thought to be more comfortable for most patients than the continuous pressure delivered by conventional CPAP therapy, although it has not been shown objectively to improve adherence. The BiPAP waveform is fixed in that it provides for set inspiratory and expiratory pressures. For example, the patient's clinically prescribed BiPAP pressures may be set at an Inspiratory Positive Airway Pressure (IPAP) =12 cm water (H2O), and Expiratory Positive Airway Pressure (EPAP) = 8 cm H2O.

The Bi-Flex® feature provides a variation of conventional BiPAP that provides a reduction in the inspiratory positive airway pressure (IPAP) provided toward the end of the inspiratory portion of the breathing cycle when the patient's inspiratory airflow normally diminishes, compared with the level of pressure provided during the majority of inspiration, and also allows reduction in the expiratory positive airway pressure (EPAP) during the initial portion of exhalation compared with that provided during the latter portion of expiration. The purpose of this modification is to provide pressure relief for the patient to smooth the transition period between the end of IPAP and the beginning of EPAP to allow for a more comfortable delivery of PAP therapy. Because Bi-Flex provides both a lower expiratory pressure and pressure relief, it has the potential to be the most comfortable mode of positive pressure therapy delivery available, and therefore to improve adherence. However, there have been no studies of adherence to therapy using Bi-Flex in either children or adults.

STUDY OBJECTIVES

1. To determine whether BiPAP with Bi-Flex as compared to CPAP results in improvement in adherence of > 30 minutes a night averaged over 3 months of home use.
2. To determine whether BiPAP with Bi-Flex as compared to CPAP results in a lower study dropout rate.
3. To determine whether Bi-Flex has similar therapeutic efficacy compared to CPAP, as determined by polysomnographic measurements of OSAS.
4. To determine whether Bi-Flex, compared to CPAP, results in improved subjective comfort and improved quality of life.
5. To determine whether objective parameters (including demographic and polysomnographic variables) or subjective parameters predict adherence.