1

Introduction

Arguably, the goal of treatment of obstructive sleep apnea (OSA) is (1) elimination or improvement of symptoms, (2) normalization or improvement of sleep study parameters, and (3) cardiovascular risk reduction in the longer term. The latter is especially true for severe OSA or for mild to moderate OSA, starting at a younger age.

In 1981, continuous positive airway pressure (CPAP) was introduced as a treatment of OSA and has been considered the gold-standard treatment of severe OSA. It acts as a pneumatic splint, or for the cyclists among us, it inflates a flat tire ( Fig. 9.1A and B ).

(A) Without NCPAP. Obstruction of the upper airway during sleep, in this case at both retropalatal and retrolingual levels. (B) With NCPAP. The positive intraluminal pressure keeps the upper airway open.

It is a safe therapeutic option with few contraindications or serious side effects. Unfortunately many patients experience CPAP therapy as intrusive, and the acceptance and (long-term) compliance of CPAP are, at best, moderate. This chapter describes various reasons for CPAP failure and discusses the clinical implications.

2

CPAP Failure

It is a clinical reality that the use of CPAP is often cumbersome and that CPAP is often not used during the whole night, 7 days a week. Patients seem to either tolerate the device well or not at all—a bimodal distribution, with an average of approximately 4 hours. Hence the term compliance was introduced. Current trends define compliance as 4 hours a night as an average over all nights observed.

CPAP compliance issues can be divided into the following: Acceptance: enduring the use of the CPAP machine in order that the optimum pressure can be adjusted; Prescription : actually starting with the therapy; Adherence : continuation of the treatment; and Tolerance : permanent acceptance of treatment without adverse reactions. Failure includes refusal of the device, withdrawal directly after initiating treatment, or failure to reduce the Apnea/Hypopnea Index (AHI) sufficiently.

Reasons for CPAP failure as shown in various studies are decreased nasal passage, dry eyes, claustrophobia, leakage of the mask, no effect, cannot fall asleep with it, and removal during sleep without awakening.

Since its introduction, the CPAP industry has constantly tried to improve the technology and has looked at ways to improve CPAP acceptance. The devices have become smaller and less noisy, with a large variation of interfaces (masks), humidification, automated pressures, and positive enforcement programs. In spite of all these attempts, a certain percentage of CPAP users continue to have serious issues. A vast body of literature exists on the subject of (long-term) compliance of CPAP, with rates ranging from 46% to 89%. Improvements in nasal continuous positive airway pressure (NCPAP) technology—in particular the introduction of automatic adjustments of the NCPAP pressure throughout the night (auto-CPAP) and attempts to enhance acceptance and compliance—have been introduced.