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Author: Chih-Ming Cheng (2007-07-12); recommended: Yeh-Liang Hsu (2007-07-13).
Note: This article is Chapter 4 of Chih-Ming Cheng’s PhD thesis “Development of a portable system for tele-monitoring of sleep in a home environment.

Chapter 4. Diagnosis interface for sleep quality and sleep problems

This chapter describes the diagnosis interface of the Sleep Guardian system, which embraces a snoring and OSAS symptoms detector (SOD) and a physical activity detecting mat (PAD-Mat). Remote and local caregivers can use this diagnosis interface to access SODs and PAD-Mats. This diagnosis program displays information from the PAD-Mat and the SOD in real-time and also provides advanced functions for further analysis and historical tracking.

This chapter is organized as follows. Section 4-1 describes the management and real-time monitoring functions of SOD and PAD-Mat. Section 4-2 and Section 4-3 discuss the PAD-Mat and SOD diagnosis report. Section 4-4 presents the sleep quality evaluation. In summary, Section 4.5 describes the applications and benefit of the Sleep Guardian system.

4.1     Management of Sleep Guardian systems

The Sleep Guardian system is designed for the remote monitoring of multi-clients. Doctors and caregivers can access several clients at the same time. Figure 4-1 shows the Management page of clients’ information, such as ID, name, IP of SOD and PAD-Mat, mobile phone number and E-mail address, which are stored in a Microsoft Access database. Three clients can be selected on the left side of the panel for real-time monitoring or for further analysis (described in section 4-2 ~ 4-4). Real-time information of the selected SOD and PAD-Mat, such as snore count, intermittent snore count, W-ISR value of an SOD, as well as the activity indexes and sleep state of a PAD-Mat are displayed.

Figure 4-1. Management page of clients’ information

Devices configuration page is an interface to test the performance of an SOD and a PAD-Mat. As show in Figure 4-2, the real-time data of an SOD and a PAD-Mat are displayed. An SOD and PAD-Mat work as a pair. It is very important to ensure the time on the SOD and the PAD-Mat are synchronized. The time adjusting function helps users to synchronize the time on the SOD and the PAD-Mat.

Figure 4-2. Devices configuration page of the Sleep Guardian system

4.2     SOD report

Figure 4-3 shows the SOD report panel of the sleep diagnosis program. After selecting a client, the user can download historical data from the SOD at this IP address (select a date and time interval and click the “download” button). Snore count and intermittent snoring count are displayed immediately in this window. Raw data of this client can be saved as a Microsoft Excel file by clicking the “SAVE” button.

Full diagnosis reports for total snore count, total intermittent snore count and total OSAS segments (in minutes) within the selected time interval can be tallied automatically. Charts of snore counts per minute versus time, intermittent snore counts per minute versus time, and OSAS segments versus time can also be drawn for further analysis (Figure 4-4). Threshold of W-ISR values can be changed for advance diagnosis (Default value of W-ISR is 0.25). Different W-ISR threshold affects sensitivity and PPV of locating OSAS segments. This adjusting feature allows doctors’ experience to be involved in the diagnosis process.

Figure 4-3. SOD report panel

Figure 4-4. Full report of SOD (OSAS patient E)

The SOD can also be combined with PAD-Mat for further OSAS diagnosis. The OSAS symptoms detected by SOD (a pause of snoring sounds) can also be caused by body position change. Therefore when combined with PAD-Mat, a one-minute segment is recognized as a normal segment if body movements are also detected. Figure 4-5 shows the SOD diagnosis report with body activity, the total OSAS segment reduced from 114 minutes to 105 minutes.

Figure 4-5. SOD diagnosis report with body activity

4.3 PAD-Mat report

Figure 4-6 shows the PAD-MAT report panel of the sleep diagnosis program. After selecting a client, the user can download historical data from the PAD-Mat at this IP address (select a date and time interval and click the “download” button). Snore count and intermittent snoring count are displayed immediately in this window. Raw data of this client can be saved as a Microsoft Excel file by clicking the “SAVE” button.

Full diagnosis reports for sleep time and total in-bed time (in minutes) within the selected time interval can be tallied automatically. Charts of ULAI per minute versus time, BAI per minute versus time, LAI versus time, In-Bed code versus time and sleep state versus time can also be drawn for further analysis (Figure 4-7). Threshold of sleep depth can be changed for advance diagnosis (Default value of sleep depth is 0.5). Different sleep depth threshold affects sensitivity and PPV of recognizing sleep segments. This adjusting feature allows the doctors’ experience to be involved in the diagnosis process.

Figure 4-6. Full report of PAD-Mat (Normal Group C)

Figure 4-7. Full report of PAD-Mat (Normal Group C)

4.4 Sleep quality report

The most commonly used measure of sleep quality is the Pittsburgh Sleep Quality Index (PSQI), which evaluates sleep quality with seven “component” scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The sum of scores for these seven components yields one global score of 1-21. Table 4-1 shows the rules for scoring sleep latency, sleep duration, sleep efficiency and sleep disturbance of the Pittsburgh Sleep Quality Index.

Table 4-1. Sleep latency, sleep duration, sleep efficiency and sleep disturbance of the Pittsburgh sleep quality index

Component

Score

0

1

2

3

Sleep Latency

15 min

16-30 min

31-60 min

> 60 min

Total Sleep Time

>480 min

360-480 min

300-360 min

<300 min

Sleep Efficiency

>85%

75-84%

65-74%

<65%

Sleep Disturbances

0

1-9

10-18

19-27

The PSQI Scores of three objective components, namely sleep latency, sleep duration, and habitual sleep efficiency, can be estimated through the asleep/awake detection of PAD-Mat. Snoring, OSAS and PLMS are 3 common sleep disturbances, which can be detected by the SOD and PAD-Mat. To smooth the strict threshold of the Pittsburgh sleep quality index, Figure 4-8 shows the fitting curves used in this research for scoring the PSQI scores. Subjects who have OSAS segments, snoring problems for 30 minutes, or awake during sleep, are scored 1 for sleep disturbances score. Figure 4-9 shows the sleep quality report of a subject with good subjective sleep quality. The subject slept well and did not go to bathroom. Figure 4-10 shows the sleep quality report of a subject with bad subjective sleep quality. The subject was unable to fall asleep for 35 minutes, and went to bathroom for 4 times. The sleep quality result of PSQI scores and subjective sleep quality are the same.

Figure 4-8. The fitting curves of PSQI

Figure 4-9. Sleep quality report of a subject with good subjective sleep quality

Figure 4-10. Sleep quality report of a subject with bad subjective sleep quality