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W Ward Flemons

Publications and source records attributed to W Ward Flemons.

13 recordsLinked to original sources
PubMed2004

Clinical usefulness of home oximetry compared with polysomnography for assessment of sleep apnea.

The practical purpose of diagnostic assessment in most cases of obstructive sleep apnea is to predict which patients have symptoms that will improve on treatment. We measured the accuracy with which clinicians make this prediction using polysomnography compared with oximeter-based home monitoring. Patients referred to a sleep center with suspicion of symptomatic obstructive sleep apnea were randomized to have polysomnography or home monitoring. Patients with comorbidity or physiologic consequences of sleep apnea were excluded. Sleep specialists estimated the likelihood of success of treatment as greater than 50% (predicted success) or less than 50% (predicted failure) on the basis of clinical data and test results. All patients were treated for 4 weeks with autoadjusting continuous positive airway pressure. Success was defined as an increase greater than 1.0 in Sleep Apnea Quality of Life Index. Correct prediction rates were compared. Two hundred eighty-eight patients were enrolled. Initial patient characteristics, compliance, and improvement in quality of life at 4 weeks were not different in the two groups. The correct prediction rate was 0.61 with polysomnography and 0.64 with home monitoring (not significant). We conclude that the ability of physicians to predict the outcome of continuous positive airway treatment in individual patients is not significantly better with polysomnography than with home oximeter-based monitoring.

Continuous Positive Airway Pressure↗
PubMed2003

A decision rule for diagnostic testing in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is traditionally diagnosed using overnight polysomnography. Decision rules may provide an alternative to polysomnography. A consecutive series of patients referred to a tertiary sleep center underwent prospective evaluation with the upper airway physical examination protocol, followed by determination of the respiratory disturbance index using a portable monitor. Seventy-five patients were evaluated with the upper airway physical examination protocol. Historic predictors included age, snoring, witnessed apneas, and hypertension. Physical examination-based predictors included body mass index, neck circumference, mandibular protrusion, thyro-rami distance, sterno-mental distance, sterno-mental displacement, thyro-mental displacement, cricomental space, pharyngeal grade, Sampsoon-Young classification, and over-bite. A decision rule was developed using three predictors: a cricomental space of 1.5 cm or less, a pharyngeal grade of more than II, and the presence of overbite. In patients with all three predictors (17%), the decision rule had a positive predictive value of 95% (95% confidence interval [CI], 75-100%) and a negative predictive value of 49% (95% CI, 35-63%). A cricomental space of more than 1.5 cm (27% of patients) excluded OSA (negative predictive value of 100%, 95% CI, 75-100%). Comparable performance was obtained in a validation sample of 50 patients referred for diagnostic testing. This decision rule provides a simple, reliable, and accurate method of identifying a subset patients with, and perhaps more importantly, without OSA.

Adult↗
PubMed2003

State of home sleep studies.

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 transducers. Type 4 monitors usually use oximetry and can be used to "rule out" sleep apnea. Higher sampling rates and improved analysis algorithms can improve the specificity of these monitors; hence, likelihood ratios for a positive test result can be high enough with some monitors to "rule in" sleep apnea as well. Not all monitors record and analyze signals in the same way; it is not possible to generalize results from one monitor across all monitors of a particular type. Limited evidence is available for many portable monitors in the unattended setting, and further research is required in this area. Clinicians should identify how they plan to use a portable monitor: as a mechanism to exclude disease in asymptomatic snorers, to confirm disease in [figure: see text] patients with a high clinical probability of disease, or to risk stratify patients so that proper priority for polysomnography can be determined. This determination allows them to select a portable monitor with signals most appropriate to their needs. The quality of the validation studies for each portable monitor also should be evaluated carefully before implementation in clinical practice. The ability for a clinician to review raw data manually and consider artifact is a necessary feature. Measurement of oxygen saturation also is important to identify patients with previously unsuspected serious desaturation that would indicate the need for more urgent treatment. In centers in which polysomnography is not readily available, a clinical decision algorithm that incorporates a clinical prediction rule with the use of portable monitors can guide clinicians toward institution of therapy or further investigations. Intuitively, this approach could reduce waiting times for polysomnography and delays in diagnosis, but additional evidence for the validity and cost effectiveness of this approach is required.

Clinical Trials as Topic↗
PubMed2003

Quality of life in sleep disorders.

Quality of life is a major outcome variable in choosing and evaluating treatment alternatives for sleep disorders. However, the number of well validated and sufficiently responsive quality of life measures for use with this population is limited. The SF-36, Nottingham Health Profile (NHP) and Sickness Impact Profile (SIP) are the most frequently used generic measures. The Functional Outcomes of Sleep Questionnaire (FOSQ) and Sleep Apnoea Quality of Life Index (SAQLI) are useful as condition/disease specific measures. However there are not yet specific measures in common use for other sleep disorders. Results across the sleep disorders that have been studied, primarily sleep apnea, narcolepsy, restless legs and insomnia, have consistently shown poorer quality of life than population norms prior to treatment, particularly in those dimensions related to sleep, energy and fatigue. Before treatment scorespes typically are of similar magnitude to those found among individuals with other chronic diseases such as hypertension and chronic obstructive pulmonary disease. With treatment quality of life scores may or may not improve to the level of population norms, suggesting that currently available treatments may not fully reverse the effects of the common sleep disorders.

Chronic Disease↗
PubMed2003

Measuring agreement between diagnostic devices.

There is growing interest in using portable monitoring for investigating patients with suspected sleep apnea. Research studies typically report portable monitoring results in comparison with the results of sleep laboratory-based polysomnography. A systematic review of this research has recently been completed by a joint working group of the American College of Chest Physicians, the American Thoracic Society, and the American Academy of Sleep Medicine. The methods for comparing the results of portable monitors and polysomnography include product-moment correlation, intraclass correlation, mean differences/limits of agreement, sensitivity, specificity, and likelihood ratios. Each approach has advantages and limitations, which are highlighted in this review.

Humans↗
PubMed2003

Comparison of home oximetry monitoring with laboratory polysomnography in children.

STUDY OBJECTIVES: To measure the accuracy and reliability of a portable home oximetry monitor with an automated analysis for the diagnosis of obstructive sleep apnea (OSA) in children. DESIGN: Prospective cohort study. SETTING: Alberta Lung Association Sleep Center, Alberta Children's Hospital Sleep Clinic. STUDY SUBJECTS: Consecutive, otherwise healthy children, aged 4 to 18 years, presenting to the Pediatric Sleep Service at the Alberta Children's Hospital for assessment of possible OSA. INTERVENTIONS: All subjects underwent 2 nights of monitoring in the home with an oximetry-based portable monitor with an automatic internal scoring algorithm. A third night of monitoring was done simultaneously with computerized laboratory polysomnography according to American Thoracic Society guidelines. MEASUREMENTS AND RESULTS: Both test-retest reliability of the portable monitor-based desaturation index (DI) between 2 nights at home and between laboratory and home were high using the Bland and Altman analysis (mean agreement, 0.32 and 0.64; limits of agreement, - 8.00 to 8.64 and - 0.75 to 6.50, respectively). The polysomnographic apnea-hypopnea index (AHI) agreed poorly with the portable monitor DI (mean difference, 1.27; limits of agreement, - 12.02 to 15.02). The sensitivity and specificity of the monitor for the identification of moderate sleep apnea (polysomnography AHI > 5/h) were 67% and 60%, respectively. CONCLUSION: Portable monitoring based only on oximetry alone is not adequate for the identification of OSA in otherwise healthy children.

Adolescent↗
PubMed2002

Validation of nasal pressure for the identification of apneas/hypopneas during sleep.

The reference standard for identifying apneas and hypopneas is a pneumotachograph, but using this can disrupt sleep. Nasal airflow estimation by measuring nasal pressure via nasal prongs is better tolerated by patients. However, nasal pressure has not been validated, using an event-by-event analysis, for detecting apneas/hypopneas during sleep. Eleven patients undergoing polysomnography wore a nasal mask capable of measuring nasal airflow (via pneumotachograph) and nasal pressure simultaneously. Each study was screened for respiratory disturbances, and from these 550 were randomly selected and blindly scored as an apnea/hypopnea or no event each using the pneumotachograph, nasal pressure, square root nasal pressure, and respiratory inductance sum signals independently. Agreement was measured using Cohen's kappa statistic. Intermeasurement agreements between the pneumotachograph and nasal pressure, square root nasal pressure, and respiratory inductance plethysmography sum were 0.76, 0.73, and 0.50, respectively. Inter- and intrarater agreements were, respectively, 0.68 and 0.60 for the pneumotachograph, 0.66 and 0.82 for nasal pressure, 0.61 and 0.78 for square root nasal pressure, and 0.47 and 0.76 for respiratory inductance plethysmography sum. These results indicate that nasal pressure has excellent agreement compared with a pneumotachograph and very good inter-/intrarater agreement. Square root transformation of the nasal pressure signal does not improve these levels of agreement, indicating that it is unnecessary in routine clinical practice for scoring apneas/hypopneas.

Adult↗
PubMed2002

Measurement properties of the calgary sleep apnea quality of life index.

Sleep apnea patients were studied three times prior to and 4 wk after a trial of nasal continuous positive airway pressure to determine the measurement properties of the Calgary Sleep Apnea Quality of Life Index (SAQLI), a disease-specific quality of life questionnaire. All patients completed the Medical Outcome Survey Short Form (SF-36), the Ferrans and Powers Quality of Life Index, and a global assessment of quality of life before and after treatment. The SAQLI was found to have a very high responsiveness index of 1.9 and an effect size of 1.1, which was much greater than the domains of the SF-36 and the FPQLI. There were statistically significant longitudinal correlations (range: 0.24 to 0.54) between the SAQLI and seven of the SF-36 domains in a pattern that was predicted beforehand and which demonstrated the validity of the SAQLI as an evaluative instrument. The SAQLI also had a range of correlations at baseline with the SF-36 (range: 0.36 to 0.71), the Epworth Sleepiness Scale (-0.26), and the FPQLI (0.29 to 0.66), and with a global rating of quality of life (0.61). The SAQLI had a high reliability coefficient of 0.92 on testing and retesting at 2 wk. We conclude that the SAQLI has excellent measurement properties for an evaluative instrument, and beginning evidence of validity as a discriminative index. It measures components of quality of life that are important to sleep apnea patients, and will be an important outcome measure in clinical trials.

Adult↗
PubMed1997

Clinical prediction of the sleep apnea syndrome.

Polysomnography, the standard diagnostic test for people suspected of having sleep apnea, is a limited resource due to its expense. Decisions about which patients to refer to a sleep center and which require polysomnography can be made based on an estimate of the probability that they have sleep apnea. Clinical features that are associated with the severity of sleep apnea, as judged by the apnea-hypopnea index, can be combined together using statistical modeling into a clinical prediction rule, whose diagnostic performance can be summarized by its sensitivity and specificity or by likelihood ratios. To date, at least seven different sleep apnea clinical prediction rules have been developed, most incorporate anthropomorphic variables such as the body mass index, waist circumference, and/or neck circumference, and some type of abnormal respiration during sleep (snoring, apneas, choking and/or gasping) witnessed by a bed partner. In general these rules have reasonably high sensitivities but only intermediate specificities, thus they can be useful in excluding the diagnosis but do not usually raise the probability of sleep apnea high enough to warrant initiating therapy without at least some type of additional testing to confirm the diagnosis. In isolation the apnea-hypopnea index is not an optimal indicator of disease severity, thus ultimately clinical decisions about the need for polysomnography and/or the need for treatment must take into account other important clinical information such as symptom severity, quality of life, and the presence or absence of comorbid illness.

Journal Article↗