State of home sleep studies
Section snippets
Classification of portable monitors
The technology for data acquisition and analysis for home monitors has evolved rapidly, and several devices have been modified repeatedly over the years. The American Academy of Sleep Medicine, formerly the American Sleep Disorders Association, developed a classification system for portable monitors based on the number and type of parameters recorded (Table 1) [7].
Defining breathing-disordered events
Although polysomnography is widely recognized as the reference standard for evaluating patients who are suspected of sleep apnea, the methods and criteria for defining events are not standardized across sleep laboratories or research studies [5]. In general, breathing disturbances are identified during polysomnography by a clear reduction in a measurement of breathing, with or without an accompanying decrease in oxygen saturation or arousal [5]. The most common method for detecting reductions
Existing guidelines and reviews
In 1994, the American Sleep Disorders Association practice parameters recommended that polysomnography remain the standard for the diagnosis, determination of severity, and treatment of sleep apnea [22]. Unattended portable recording was viewed as an acceptable alternative only under the following circumstances: (1) when initiation of treatment was urgent and polysomnography unavailable, (2) when patients could not undergo polysomnography because of mobility issues, or (3) as a follow-up to
Rating the evidence
To avoid bias in assessing a diagnostic test such as a portable monitor, several key factors must be considered. Selection bias may be introduced if consecutively referred patients are not used. Verification bias may be introduced if the decision to perform a reference standard (in this case, polysomnography) is influenced by the results of the test being evaluated (a portable monitor). Table 2 depicts how the system by Sackett et al [26] for rating evidence would apply to studies evaluating a
Further research directions
Additional research on portable monitors is required to address several issues. Most monitors have been studied by only a single group of investigators. All studies have taken place on patients referred to a sleep center. It is yet to be proven what the effect of changing the studied clinical population would have on the diagnostic performance of these monitors. Primary care populations, women, non-whites, and patients with comorbid illness have not been studied adequately; therefore, the
Portable monitors in a clinical decision algorithm
Like any diagnostic test, the results of testing with portable monitors are most useful when applied to the appropriate clinical context. The results of a negative portable monitoring study would have different implications for a mildly symptomatic patient with a low pretest probability compared with a symptomatic patient with a high pretest probability. The probability that a patient has sleep apnea based on clinical factors alone can be estimated using one of several clinical prediction rules
Summary
Many different portable monitors have been used to assess patients with suspected sleep apnea. There is limited evidence for the use of type 2 monitors, especially in the unattended setting in which there may be high rates of data loss. Type 3 monitors have low likelihood ratios for negative tests and can be used to “rule out” sleep apnea. The ability of type 3 monitors to “rule in” sleep apnea is less convincing, but this may improve with the use of improved technology, such as nasal pressure
References (43)
- et al.
Clinical value of polysomnography
Lancet
(1992) - et al.
Home oximetry studies for diagnosis of sleep apnea/hypopnea syndrome: limitation of memory storage capabilities
Chest
(2001) - et al.
Does oximetry contribute to the detection of apneic events? Mathematical processing of the SaO2 signal
Chest
(1991) - et al.
Portable computerized polysomnography in attended and unattended settings
Chest
(1999) - et al.
Validation of the POLY-MESAM seven-channel ambulatory recording unit
Chest
(2000) - et al.
MESAM 4: an ambulatory device for the detection of patients at risk for obstructive sleep apnea syndrome (OSAS)
Chest
(1992) Obstructive sleep apnea
N Engl J Med
(2002)- et al.
The occurrence of sleep-disordered breathing among middle-aged adults
N Engl J Med
(1993) - et al.
Prospective study of the association between sleep-disordered breathing and hypertension
N Engl J Med
(2000) - et al.
The natural history of the development of obesity in a cohort of young US adults between 1981 and 1998
Ann Intern Med
(2002)
Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research
Sleep
Portable recording in the assessment of obstructive sleep apnea
Sleep
Assessment of accuracy and analysis time of a novel device to monitor sleep and breathing in the home
Sleep
Verification of sleep apnea using a portable sleep apnea screening device
South Med J
Importance of the pulse oximeter averaging time when measuring oxygen desaturation in sleep apnea
Sleep
Accuracy of oximetry with thermistor (oxiflow) for diagnosis of obstructive sleep apnea and hypopnea
Sleep
Model for investigating snorers with suspected sleep apnea
Thorax
Automated analysis of digital oximetry in the diagnosis of obstructive sleep apnoea
Thorax
A comparison of clinical assessment and home oximetry in the diagnosis of obstructive sleep apnea
Am Rev Respir Dis
Digital monitoring of sleep-disordered breathing using snoring sound and arterial oxygen saturation
Am Rev Respir Dis
Diagnostic accuracy of a portable recording device (MESAM IV) in suspected obstructive sleep apnoea
Eur Respir J
Cited by (13)
Pulse transit time in paediatric respiratory sleep studies
2007, Medical Engineering and Physics