ABSTRACT
INTRODUCTION Auto-positive airway pressure (APAP) devices provide a useful alternative for providing positive airway pressure (PAP) treatment for patients w ith obstructive sleep apnea (OSA) (1-3). One can separate the uses of these devices into two large categories (Table 1). These include: (i) auto-titration PAP to determine an effective fixed level of continuous positive airway pressure (CPAP) and (ii) auto-adjusting PAP for chronic treatment. When used in the auto-titration mode the devices are used by the patient for a period of time (one night to several weeks). Information stored in the device is transferred to a computer and can be used to select an optimal fixed level of CPAP for chronic treatment. When APAP devices are used for chronic treatment they have the potential advantage of delivering the lowest effective pres sure in any circumstance (body position, sleep stage). The mean pressure for the night may be lower than a single pressure that would be effective in all circum stances (the prescription pressure). For example, higher CPAP is usually needed in the supine posture and during rapid eye movement (REM) sleep (4-6). A schematic representation of the delivered pressure profile for a single night on auto-adjusting PAP is shown in Figure 1. In this example, the patient spent only a small portion of the night at the higher pressure required for the supine position. The average pressure is much lower than a single pressure that would be effective throughout the night. A substantial literature now exists evaluating the use of the devices in these modes of operation.
