Author: Chih-Ming Cheng (2007-07-15);
recommended: Yeh-Liang Hsu (2007-07-15).
Note: This article is Chapter 5 of Chih-Ming Cheng’s PhD thesis “Development
of a portable system for tele-monitoring of sleep in a home environment”.
Chapter 5. Conclusion and
Sleep is a basic
physiological need of all humans. About 35% of all adult American was afflicts
by insomnia during the course of a year [Mellinger, et al., 1985]. According to
statistics of “2001 Social Development Trends Survey”, over 10% of those 15 and
older Taiwanese rated their sleep quality less than perfect. About 15% of the
subjects reported to have PLMS and over 30% of the elder suffer from the same
problem [Directorate-General of Budget, Accounting and Statistics of Taiwan,
2001]. Significant research activities are underway in the development of sleep
monitoring systems. However, a basic problem is that, it requires specialists
with a high degree of technical expertise and the use of an expensive
polygraph. Nowadays, small, portable, non-invasive, non-constrictive, non-conscious
and remote monitoring techniques are new approaches for sleep monitoring at
develops a tele-monitoring system for sleep (called the Sleep Guardian system)
based on the Portable Telehomecare Monitoring System (PTMS) structure. This
system embraces a snoring and OSAS symptoms detector (SOD), a physical activity
detecting system (PAD-Mat) and a sleep diagnosis interface. The Sleep Guardian system
on-line monitors the symptoms of sleep-related disorders and evaluates sleep
stages and sleep quality via physical activity data. This portable
tele-monitoring system provides a convenient approach to better understand and
recognize sleep-related problems.
5.1 Possible applications of the Sleep Guardian system
applications are purposed in this research. The Sleep Guardian system can be
used as prior examinations for sleep-related breathing disorders and PLMS, a
tool for sleep quality evaluating and an assistant for nursing home supporting.
practices, excessive daytime sleepiness is the major symptom of patients with
obstructive sleep apnea syndrome (OSAS). Epworth Sleepiness Scale (ESS), a
simple questionnaire measuring the general level of daytime sleepiness, is used
to forewarn the possibility of OSAS. Patients with higher scores of ESS (over
10) were assigned to have PSG examinations. Although some researches showed the
relation of sleepiness to respiratory disturbance [Gottlieb, et al., 1999],
some others also have different point of view. Chervin and Aldrich used
regression models and retrospective data from a relatively large series of 237
patients and concluded that the ESS may not reflect objective measures of sleep
apnea [Chervin and Aldrich, 1999]. Guilleminault et al. also pointed out that respiratory
disturbance index and oxygen saturation indices did not significantly correlate
with daytime sleepiness [Guilleminault, eta al., 1988]. However, the ESS tends
to amplify the possible of OSAS. In this research, “Development of a portable system
for tele-monitoring of sleep in a home environment”, 18 patients who had high
scores were selected for one-night PSG examination. Only 5 of 18 patients
(27.8%) were classified as OSAS patient by PSG.
The SOD showed a
good performance in detecting snore and locating OSAS segments (an average
sensitivity of 94.0% and 79.6%). The SOD is not intended to be a diagnosis
device for OSAS, instead, this portable device is to be used as a home
appliance as a precautionary measure for monitoring snoring and OSAS.
Sleep quality assessment
research, the sleep quality evaluation is based on the Pittsburgh Sleep Quality
Index (PSQI). The PSQI was designed to differentiate between good and poor
sleepers, and to measures sleep disturbances using self-reports. Using a
cut-off score of 5, high sensitivity and specificity of 89.6% and 86.5% was
reported with the original publication of measure [Buysse, et al., 1988]. Nevertheless,
PSQI scores did not correlate well with their PSG counterparts, with the
strongest relationship between PSQI and PSG sleep latency being only r = 0.3.
Guardian system provides a quantitative measurement of sleep disturbances and
evaluates sleep quality with objective estimates by the PAD-Mat and the SOD.
Sleep/Awake cycle was recognized by the PAD-Mat and was validated with good
sensitivity and specificity in identifying sleep states (89.5% and 84.3%). This
portable device is to be used as a home appliance for better understanding
Physical activity detection
There are also
motor disturbances that are triggered by sleep, such as restless legs syndrome
(RLS) and periodic limb movements during sleep (PLMS). The PAD-Mat is a non-constrain
approach to detecting motor disturbances in sleep.
disturbances monitoring and sleep quality assessment, the PAD-Mat can be used
for detecting body position changes. Bed sore is a common problem in nursing
home. Usually caregivers have to change the subject’s body position every 2 hour.
Figure 5-1 shows a 3-day history of a subject in a nursing home. Caregivers and
family members can access the PAD-Mat for body activity tracking.
Figure 5-1. 3-day history of a subject in a
5.2 Future work
The future work
of this research will focus on the commercialization of the system. More user
trials are to be conducted to evaluate the user acceptance, clinical effect,
and economic analysis of the Sleep Guardian system. Besides the management
interface described in Chapter 4, an IE user interface written in Java is to be
developed, so that the caregiver can access SOD and PAD-Mat directly from any
client PC. With the two sensors (SOD and PAD-Mat) and the PTMS information
structure, there are more possible applications in home telehealth. Other
possible applications are to be explored in the future.
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and Aldrich, M. S., “The Epworth Sleepiness Scale may not reflect objective
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