Clinical prediction of the sleep apnea syndrome

Relation between oro-facial thermographic findings and myofunctional characteristics in patients with obstructive sleep apnoea

AIM

To evaluate the thermographic characteristics of oro-facial structures and submental triangle of participants with obstructive sleep apnoea (OSA), as well as to investigate its correlation with the anatomy, posture and functions of the oro-facial structures.

METHOD

Eighteen patients diagnosed with OSA by polysomnography (OSA group; 57.4 ± 15.8 years) and 13 healthy participants screened for OSA (control group; 57.8 ± 18.1 years) were included. All participants answered to questionnaires for OSA and excessive daytime sleepiness, and were submitted to infrared image thermography analysis of facial regions of interest (ROIs), oro-facial myofunctional evaluation (OMES-E protocol) and masticatory performance. Statistical analysis included one-way ANOVA and Pearson/Spearman correlation test.

RESULTS

Obstructive sleep apnoea group showed lower thermographic measures in many ROIs in the frontal and lateral views of the face, including the submental triangle region, and lower scores of aspect/posture and performance of oro-facial structures, as well lower total score of OMES-E evaluation (P < .05). Scores of aspect/posture and mobility were correlated with the temperature of some ROIs in the frontal and lateral views.

CONCLUSION

Lower facial skin and submental triangle region temperatures, measured by infrared thermography, and a worse oro-facial myofunctional condition were identified in the group of individuals with OSA. The higher temperatures of the ROIs were correlated with the better status of aspect/posture and performance of the oro-facial myofunctional structures.

CPAP treatment in REM-related obstructive sleep apnea: a distinct clinical phenotype of sleep disordered breathing

PURPOSE

REM-related obstructive sleep apnea (REM-OSA), as defined using revised apnea-hypopnea index (AHI) criteria, might represent a specific OSA phenotype. However, there is a lack of data on outcomes of treatment in this population. This study evaluated the effects of CPAP treatment over 12 months on clinical outcomes for patients with the polysomnography phenotype of REM-OSA.

METHODS

We conducted a prospective observational study with the following inclusion criteria: subjective sleepiness and diagnostic polysomnography demonstrating AHI_REM≥15 events/h, AHI_NREM<5 events/h, and ≥ 30 min of REM sleep. Clinical outcomes assessed included Epworth Sleepiness Scale (ESS), psychomotor vigilanc test reaction time (PVT-RT), and CPAP adherence at baseline, 1, 3, 6, and 12 months; Functional Outcomes of Sleep Questionnaire (FOSQ) and Depression Anxiety Stress Scales (DASS-21) at baseline, 1, 3 and 12 months. The reason is the first 3 outcomes (ESS, PVT, adherence) were assessed at baseline, 1, 3, 6, and 12 months, while the next 2 outcomes (FOSQ, DASS) were assessed at baseline, 1, 3, and 12 months. The edited version is not as clear in separating these outcomes into 2 groups; Functional Outcomes of Sleep Questionnaire (FOSQ); and Depression Anxiety Stress Scales (DASS-21) at baseline, 1, 3, and 12 months. Linear mixed effects models were used to investigate the joint effects of time and average CPAP adherence on our outcomes of interest.

RESULTS

Twenty participants completed a minimum of 1 month of CPAP treatment and were included for analysis. During the trial, 8 participants discontinued CPAP (4 before 3 months, 1 before 6 months, 3 before 12 months), and 19 participants completed 12 months of treatment. Baseline ESS was elevated at 12.6 units. Average CPAP usage for all 27 participants over 12 months was 2.9 ± 2.4 h. There was a significant decrease in ESS and increase in FOSQ at all time points, and the decrease in ESS was only seen in the CPAP-adherent subgroup. Decreases in DASS-21 and PVT-RT were not sustained.

CONCLUSIONS

CPAP treatment in sleepy patients with moderate to severe REM-OSA is associated with reduced sleepiness and improved quality of life.

TRIAL REGISTRATION

The trial was registered in the Australian New Zealand Clinical Trials Registry: ACTRN12620000576921, 18/05/2020 (retrospectively registered).

Effect of the duration of protease inhibitor therapy in HIV-infected individuals on the severity of obstructive sleep apnea

Background

Protease inhibitors (PIs) are a vital part of the antiretroviral therapy. Long-term use of PIs may cause lipodystrophy, a clinical syndrome characterized by peripheral lipoatrophy and central fat accumulation, which may increase the risk of developing obstructive sleep apnea (OSA) in HIV-infected patients. We hypothesize that a longer duration of PIs' use might be associated with increasing severity of OSA in HIV-infected patients.

Materials and Methods

This was a retrospective cohort study of HIV-infected patients who were treated with PIs, who presented with symptoms suggestive of OSA, and underwent nocturnal polysomnography. The primary objective of the study is to evaluate the association between the duration of PIs' use and the severity of OSA. The duration of PIs' use measured in months was recorded for each patient. The primary outcome of interest was the apnea-hypopnea index (AHI) obtained at the time of the sleep study. Data were analyzed using univariate and multivariate linear regression between AHIs with PIs' use as well as other predictors.

Results

A total of 54 patients diagnosed with HIV and OSA were included in the study cohort for the analysis. Sleep study body mass index (BMI; P = 0.042) and change in BMI (ΔBMI; P = 0.027) were the only statistically significant independent predictors of AHI. The association between AHI and PIs' use duration was found to be nonlinear and nonsignificant. Gender differences evaluation suggested possible duration-related effect relationship between PIs and OSA severity among HIV-infected men exposed to PIs within a 66-month duration.

Conclusion

We did not observe a significant association between PIs' use duration and the severity of OSA.

Comparing REM- and NREM-Related Obstructive Sleep Apnea in Jordan: A Cross-Sectional Study

Obstructive sleep apnea (OSA) is a common disorder that includes an intermittent mechanical obstruction of the upper airway during sleep, which can occur either during rapid eye movement (REM) phase or non-REM (NREM) phase. In this study, we aim to evaluate the differences in demographic and polysomnographic features between REM- and NREM-related OSA in a Jordanian sample, using both the broad and the restricted definitions of REM-related OSA. All patients who were referred due to clinical suspicion of OSA and underwent sleep study were screened. We included patients with a diagnosis of OSA who had Apnea-Hypopnea Index (AHI) greater than or equal to five. We classified patients into REM-related OSA according to either the broad definition (AHI_REM/AHI_NREM ≥ 2) or the strict definition (AHI_REM > 5 and AHI_NREM < 5 with a total REM sleep duration of at least 30 minutes), and patients with AHI_REM/AHI_NREM less than two were classified as NREM-related OSA. A total of 478 patients were included in this study with a mean age of 55.3 years (±12.6). According to the broad definition of REM-related OSA, 86 (18%) of OSA patients were classified as having REM-related OSA compared to only 13 (2.7%) patients according to the strict definition. Significant differences were found between both NREM-related OSA and REM-related OSA according to the broad and to the strict definitions for arousal index (p < 0.001 and p < 0.032), respectively, duration of saturation below 90% (p < 0.001 for both), and saturation nadir (p < 0.036 and p < 0.013), respectively. No significant differences were found between this group and other OSA patients regarding age, BMI, ESS, and snoring. Our study showed that the stricter the definition for REM-related OSA, the milder the associated clinical changes.

Can Statistical Machine Learning Algorithms Help for Classification of Obstructive Sleep Apnea Severity to Optimal Utilization of Polysomno graphy Resources?

Objectives: The goal of this study is to evaluate the results of machine learning methods for the classification of OSA severity of patients with suspected sleep disorder breathing as normal, mild, moderate and severe based on non-polysomnographic variables: 1) clinical data, 2) symptoms and 3) physical examination.

Methods: In order to produce classification models for OSA severity, five different machine learning methods (Bayesian network, Decision Tree, Random Forest, Neural Networks and Logistic Regression) were trained while relevant variables and their relationships were derived empirically from observed data. Each model was trained and evaluated using 10-fold cross-validation and to evaluate classification performances of all methods, true positive rate (TPR), false positive rate (FPR), Positive Predictive Value (PPV), F measure and Area Under Receiver Operating Characteristics curve (ROC-AUC) were used.

Results: Results of 10-fold cross validated tests with different variable settings promisingly indicated that the OSA severity of suspected OSA patients can be classified, using non-polysomnographic features, with 0.71 true positive rate as the highest and, 0.15 false positive rate as the lowest, respectively. Moreover, the test results of different variables settings revealed that the accuracy of the classification models was significantly improved when physical examination variables were added to the model.

Conclusions: Study results showed that machine learning methods can be used to estimate the probabilities of no, mild, moderate, and severe obstructive sleep apnea and such approaches may improve accurate initial OSA screening and help referring only the suspected moderate or severe OSA patients to sleep laboratories for the expensive tests.

Nasopharyngeal dimensions in normal individuals: normative data

OBJECTIVE

To establish normative values of minimum cross-sectional nasopharyngeal area in individuals without craniofacial anomalies at different age ranges.

MATERIAL AND METHOD

Ninety-six individuals of both genders, without craniofacial anomalies, and with normal body mass index and neck circumference were evaluated. Participants were divided into 4 age groups: children, aged 6 to 10 years (G1); adolescents, aged 11 to 17 years (G2); young adults, 18 to 39 years (G3), and middle-aged adults, 40 to 59 years (G4). Minimum cross-sectional nasopharyngeal area (nasopharyngeal area - NPA) was assessed by means of modified anterior rhinomanometry (pressure-flow technique) using a PERCI-SARS system (version 3.50 - Microtronics Corp.).

RESULTS

Mean±SD values of NPA were 1.025±0.054cm2, 1.055±0.081cm2, 1.050±0.083cm2, and 1.054±0.081cm2, respectively for groups G1, G2, G3, and G4, showing that there were no differences between the four age groups.

CONCLUSION

Normative data of NPA were established for individuals without craniofacial anomalies from different age ranges, and they may be used as reference values in the clinical routine and for future studies regarding nasopharyngeal obstruction diagnosis, particularly in cases of craniofacial anomalies.

Obstructive sleep apnea, sleep disorders, and perioperative considerations

Data suggest that surgical patients with obstructive sleep apnea (OSA) may be difficult to ventilate and intubate, and may be prone to postoperative complications. This article addresses the identification of patients at risk for OSA, epidemiology of the disorder, and treatment options, as well as the perioperative management of this population.

Obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common clinical condition in which the throat narrows or collapses repeatedly during sleep, causing obstructive sleep apnoea events. The syndrome is particularly prevalent in middle-aged and older adults. The mechanism by which the upper airway collapses is not fully understood but is multifactorial and includes obesity, craniofacial changes, alteration in upper airway muscle function, pharyngeal neuropathy and fluid shift towards the neck. The direct consequences of the collapse are intermittent hypoxia and hypercapnia, recurrent arousals and increase in respiratory efforts, leading to secondary sympathetic activation, oxidative stress and systemic inflammation. Excessive daytime sleepiness is a burden for the majority of patients. OSAS is also associated with cardiovascular co-morbidities, including hypertension, arrhythmias, stroke, coronary heart disease, atherosclerosis and overall increased cardiovascular mortality, as well as metabolic dysfunction. Whether treating sleep apnoea can fully reverse its chronic consequences remains to be established in adequately designed studies. Continuous positive airway pressure (CPAP) is the primary treatment modality in patients with severe OSAS, whereas oral appliances are also widely used in mild to moderate forms. Finally, combining different treatment modalities such as CPAP and weight control is beneficial, but need to be evaluated in randomized controlled trials. For an illustrated summary of this Primer, visit: http://go.nature.com/Lwc6te.

Screening for obstructive sleep apnoea in obesity and diabetes--potential for future approaches

BACKGROUND

It is recognised that sleep-disordered breathing (SDB), in particular, obstructive sleep apnoea (OSA) is associated with obesity and diabetes. The complications of OSA include dysregulation of metabolic and cardiovascular homeostasis. With the growing population of diabetes and obesity globally, it is becoming apparent that identifying and screening patients who are at risk is becoming increasingly crucial. Many patients may remain unaware of the potential diagnosis and continue to be undiagnosed. The high prevalence of OSA poses a demanding challenge to healthcare providers in order to provide sufficient resources and facilities for patient diagnosis and treatment.

DESIGN

In this article, we review the evidence in favour of screening populations deemed to be at increased risk of OSA, with particular reference to patients with obesity and diabetes. We consider the recent advances in potential screening methods that may allow new prognostic and predictive tools to be developed. A detailed search of Medline and Web of Science electronic databases for relevant articles in English was performed.

RESULTS

Apart from the use of screening tools such as questionnaires and clinical decision models, there is increasing evidence to suggest that there are differences in biological parameters in patients with OSA. Although further studies are required, there may be potential for such biomarkers to contribute to and augment the screening process. However, the significance of such biological tools remains to be elucidated.

CONCLUSIONS

A fundamental role for improved screening in patients with conditions such as obesity and diabetes can enable early interventions that may improve health outcomes relating to the adverse consequences of OSA. The future will see further research being carried out in the development of potential screening methods with emphasis on the selection of patients at risk of sleep disorders, thereby allowing more detailed physiological studies to be carried out where needed.

Functional outcomes in patients with REM-related obstructive sleep apnea treated with positive airway pressure therapy

STUDY OBJECTIVES

To evaluate functional outcomes in adults with REM-related obstructive sleep apnea (OSA) treated with positive airway pressure (PAP) therapy.

DESIGN

Retrospective observational study.

SETTING

Outpatient sleep clinic.

PATIENTS

330 adults (171 males) with OSA receiving PAP therapy, including 130 with REM OSA and 200 with OSA not restricted to REM.

MEASUREMENTS AND RESULTS

REM OSA was defined as a REM apnea-hypopnea index (AHI) / NREM AHI > 2 and NREM AHI < 15. Patients had baseline and post-PAP functional outcomes, including Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), Patient Health Questionnaire-9 (PHQ-9), and Functional Outcomes Sleep Questionnaire (FOSQ) scores. We compared functional outcomes, demographic, clinical and polysomnographic features, and PAP adherence in patients with REM OSA and OSA not restricted to REM. Female gender was significantly more common in REM OSA. Age, BMI, neck girth, and baseline ESS, FSS, PHQ-9, and FOSQ were similar between groups. Smoking history and comorbid disorders were also similar except for a higher prevalence of depression and cardiovascular disease in OSA not restricted to REM. All functional outcomes improved significantly after PAP therapy in both groups. Change from baseline to post treatment was similar for all functional outcomes between groups.

CONCLUSIONS

The study is the first addressing clinical outcomes in REM OSA using validated measures. Functional outcomes in patients with REM OSA improve after treatment with PAP therapy comparable to that observed in patients with OSA not restricted to REM.

COMMENTARY

A commentary on this article appears in this issue on page 249.

Frequently used sleep questionnaires in epidemiological and genetic research for obstructive sleep apnea: a review

BACKGROUND & AIMS

Many sleep questionnaires are utilized by the epidemiological and genetic research communities. This paper reviewed sleep-related questions and answers commonly used in epidemiological studies (focused on sleep apnea and snoring), with an emphasis on the utility of the response options.

METHODS

A literature search was conducted to identify relevant sleep questionnaires. Questionnaires were limited to the English language and had to include questions specific to snoring or stop breathing during sleep. Questionnaires had to demonstrate a citation count >10 through Web of Science. A comparison of questions and answers, and elements important in the design of good quality instruments was conducted.

RESULTS

Fourteen questionnaires met the inclusion criteria for final review. Validation was conducted for many of these instruments, though the methods and validation populations were highly variable. Study sample sizes were also relatively small and differed in methods of data analysis. These questionnaires were very heterogeneous, with only some (n = 6) allowing a "don't know" alternative. Six specified the time period referred to as "past month", one referred to "last three months" and the remaining questionnaires had no specific timeframe. The response alternatives to specific questions were Yes/No (n = 5), wording only like "never", "seldom", "often" (n = 4), or a frequency scale indicating times per week (n = 8).

CONCLUSIONS

There is a need for improved standardized instruments not only to capture relevant sleep information but also to allow greater comparability between studies.

Consenso brasileiro de ronco e apneia do sono: aspectos de interesse aos ortodontistas

O objetivo deste artigo é explicitar o posicionamento das sociedades médicas que, reunidas, estabeleceram consenso sobre os parâmetros clínico-laboratoriais que envolvem os distúrbios respiratórios do sono, em especial o ronco e a síndrome da apneia obstrutiva do sono (SAOS). Os ortodontistas, que vêm ocupando gradativamente seu espaço em equipes multidisciplinares que atuam na área do sono humano, pouco conhecem sobre essa uniformização coordenada pela Associação Brasileira de Sono. Os trabalhos clínicos e as pesquisas científicas oriundos da Odontologia, e em particular da Ortodontia, também devem observar e seguir esses critérios de diagnóstico e tratamento estabelecidos pela comunidade médica brasileira.

Clinical assessment of the obstructive sleep apnoea/hypopnoea syndrome

This review focuses on the clinical presentation of the obstructive sleep apnoea/hypopnoea syndrome in adults. Features consistent with the diagnosis are described. A brief discussion of the objective measurement of sleep-disordered breathing, largely in the form of overnight monitoring, is undertaken.

Nocturia and snoring: predictive symptoms for obstructive sleep apnea

PURPOSE

Current screening for obstructive sleep apnea (OSA) emphasizes self-reported snoring and other breathing symptoms. Nocturia, a symptom with a precise pathophysiological link to sleep apnea, has not been assessed as a screening tool for this common disorder of sleep respiration. In a large sample of adults presenting to area sleep centers, we aimed to determine the predictive power of nocturia for OSA and compare findings with other markers of OSA commonly used to screen for this disease.

METHODS

This was a retrospective chart review. A consecutive sample of 1,007 adult patients seeking treatment at two sleep centers in New Mexico completed detailed medical and sleep history questionnaires and completed diagnostic polysomnography testing. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of nocturia, snoring, high body mass index, sex, and age for OSA were determined. Hierarchical linear regression determined unique variance contribution to the apnea-hypopnea index, the objective measure of sleep apnea severity.

RESULTS

The results are as follows: sensitivities--snoring, 82.6% and nocturia, 84.8%; specificities--snoring, 43.0% and nocturia, 22.4%; PPVs--snoring, 84.7% and nocturia, 80.6%; and NPVs--snoring, 39.6% and nocturia, 27.9%. With hierarchical linear regression, patient-reported nocturia frequency predicted apnea-hypopnea index (OSA severity) above and beyond body mass index, sex, age, and self-reported snoring (P<0.0001).

CONCLUSIONS

Nocturia appears comparable to snoring as a screening tool for OSA in patients presenting to a sleep medical center. Research in urology and primary care clinics is needed to definitively clarify the use of nocturia as a screening instrument for obstructive sleep apnea.

Prevalence of Sleep Apnea in Morbidly Obese Patients who Presented for Weight Loss Surgery Evaluation: More Evidence for Routine Screening for Obstructive Sleep Apnea before Weight Loss Surgery

The incidence of obstructive sleep apnea has been underestimated in morbidly obese patients who present for evaluation for weight loss surgery. This retrospective study shows that the incidence of obstructive sleep apnea in this patient population is greater than 70 per cent and increases in incidence as the body mass index increases. Obstructive sleep apnea (OSA) is a common comorbidity in obese patients who present for evaluation for gastric bypass surgery. The incidence of sleep apnea in obese patients has been reported to be as high as 40 per cent. A retrospective review of our prospectively collected database was performed. All patients being evaluated for weight loss surgery for obesity were screened preoperatively for OSA using a sleep study. The overall incidence of sleep apnea in our patients was 78 per cent (227 of 290). All 227 were diagnosed by formal sleep study. There were 63 (22%) males and 227 (78%) females. The mean age was 43 years (range, 17–75 years). The mean body mass index (BMI) was 52 kg/m2 (range, 31–94 kg/m2). The prevalence of OSA in the severely obese group (BMI 35–39.9 kg/m2) was 71 per cent. For the morbidly obese group (BMI 40–40.9 kg/m2), the prevalence was 74 per cent and for the superobese group (BMI 50–59.9 kg/m2) 77 per cent. Those with a BMI 60 kg/m2 or greater, the prevalence of OSA rose to 95 per cent. The incidence of sleep apnea in patients presenting for weight loss surgery was greater than 70 per cent in our study. Patients presenting for weight loss surgery should undergo a formal sleep study to diagnose OSA before bariatric surgery.

Obese obstructive sleep apnea patients with tonsil hypertrophy submitted to tonsillectomy

The physiopathology of obstructive sleep apnea-hypopnea syndrome (OSAHS) is multifactorial and obesity has been shown to be one of the main factors correlated with its occurrence. In obese patients with anatomical alterations of the upper airways it is often difficult to predict success for surgical correction since obesity is a limiting factor. Therefore, the aim of the present study was to evaluate the results of tonsillectomy in a specific group of patients, i.e., obese OSAHS patients with tonsil hypertrophy. Seven OSAHS patients with moderate obesity with obstructive palatine tonsil hypertrophy were submitted to tonsillectomy. All patients were submitted to pre- and postoperative appraisal of body mass index, otorhinolaryngology examination and polysomnography. Patients' average age was 36.4 +/- 10.3 years and average preoperative body mass index was 36.6 +/- 6.3 kg/m(2). Postoperative weight did not differ significantly from preoperative weight (P = 0.27). Average preoperative apnea and hypopnea index (AHI) was 81 +/- 26/h and postoperative AHI was 23 +/- 18/h (P = 0.0005). Average preoperative minimum oxyhemoglobin saturation (SaO2 min) was 69 +/- 14% and the postoperative value was 83 +/- 3% (P = 0.038). In relation to AHI, 6 (86%) of the 7 patients studied showed a reduction of 50% in relation to preoperative level and of these, 4 (57%) presented AHI of less than 20%. Only one patient presented a reduction of less than 50% in AHI, but even so showed improved SaO2 min. Tonsillectomy treatment for OSAHS in obese patients with obstructive palatine tonsil hypertrophy caused a significant reduction in AHI, with improvement in SaO2 min. This procedure could be eventually considered as an option of treatment for obese OSAHS patients with significant tonsil hypertrophy when continuous positive air pressure therapy is not possible as the first choice of treatment.

Patient- and bed partner-reported symptoms, smoking, and nasal resistance in sleep-disordered breathing

OBJECTIVES

Nocturnal and daytime symptoms are important determinants in clinical decision making in patients suspected of having sleep-disordered breathing (SDB). We compared patients' and bed partners' reporting of symptoms associated with SDB in a clinical sample of snoring men. The bed partners' view on snoring disturbance was assessed. The relationship between sleep parameters, anthropometric data, and selected subjective symptoms was assessed. Additionally, we evaluated the relationship between smoking, nasal resistance, and habitual snoring.

DESIGN

A cross-sectional, prospective study.

SETTING

University teaching hospital.

PATIENTS

Thirty-seven consecutive snoring men referred to ENT Hospital because of a snoring problem or suspicion of sleep apnea, and scheduled for surgical treatment of nasal obstruction.

INTERVENTIONS

The patients completed a sleep questionnaire, a questionnaire on nasal history, and the Epworth sleepiness scale. The bed partners were asked to complete a separate sleep questionnaire of the patient's daytime and nocturnal symptoms. Both patients and bed partners evaluated the intensity of snoring on a visual analog scale. The patients underwent polysomnography and anterior rhinomanometry.

RESULTS

Agreement of patients' and bed partners' reports on symptoms related to SDB was good in this material. One half of the bed partners were disturbed by snoring every night or almost every night, and one third of the bed partners reported disharmony in the relationship from time to time or repeatedly due to snoring. The combination of current smoking and total nasal resistance in a supine position higher than the median value in this patient sample was associated with history of habitual snoring.

CONCLUSIONS

Male patients and their bed partners seem to give congruent reports of snoring and symptoms related to SDB in a clinical population with mild SDB. One half of the bed partners found their sleep constantly disturbed. The combination of current smoking and high nasal resistance was related with habitual snoring.

A new method of negative expiratory pressure test analysis detecting upper airway flow limitation to reveal obstructive sleep apnea

BACKGROUND

Expiratory flow limitation (EFL) by negative expiratory pressure (NEP) testing, quantified as the expiratory flow-limited part of the flow-volume curve, may be influenced by airway obstruction of intrathoracic and extrathoracic origins. NEP application during tidal expiration immediately determines a rise in expiratory flow (V) followed by a short-lasting V drop (deltaV), reflecting upper airway collapsibility.

PURPOSES

This study investigated if a new NEP test analysis on the transient expiratory DeltaV after NEP application for detection of upper airway V limitation is able to identify obstructive sleep apnea (OSA) subjects and its severity.

METHODS

Thirty-seven male subjects (mean +/- SD age, 46 +/- 11 years; mean body mass index [BMI], 34 +/- 7 kg/m2) with suspected OSA and with normal spirometric values underwent nocturnal polysomnography and diurnal NEP testing at - 5 cm H2O and - 10 cm H2O in sitting and supine positions.

RESULTS

deltaV (percentage of the peak V [%Vpeak]) was better correlated to apnea-hypopnea index (AHI) than the EFL measured as V, during NEP application, equal or inferior to the corresponding V during control (EFL), and expressed as percentage of control tidal volume (%Vt). AHI values were always high (> 44 events/h) in subjects with BMI > 35 kg/m2, while they were very scattered (range, 0.5 to 103.5 events/h) in subjects with BMI < 35 kg/m2. In these subjects, AHI still correlated to deltaV (%Vpeak) in both sitting and supine positions at both NEP pressures.

CONCLUSIONS

OSA severity is better related to deltaV (%Vpeak) than EFL (%Vt) in subjects referred to sleep centers. DeltaV (%Vpeak) can be a marker of OSA, and it is particularly useful in nonseverely obese subjects.

The biology and genetics of obesity and obstructive sleep apnea

This article reviews current knowledge about a genetic approach to the causes and risk factors for sleep apnea. Recent evidence suggests that genetic variability may play a significant causal role in the pathogenesis of obstructive sleep apnea. The data supporting a genetic influence on sleep apnea, and the perioperative management of patients with sleep apnea are examined.

Obstructive Sleep Apnea-Hypopnea Syndrome

OSAHS should be an expected condition in many patients encountered by primary care providers. The diagnosis may arise because of patient daytime dysfunction, partner prompting, or in the course of managing comorbidities adversely influenced by the hemodynamic, neural, humoral,and inflammatory consequences of repetitive desaturations and arousals.OSAHS should be suspected in patients who exhibit habitually loud snoring, witnessed apneas/choking/gasping during sleep, hypertension, neck circumferences of 17 inches or greater, obesity, and laterally narrowed oropharynxes. Diagnosis is established by polysomnography. CPAP is the treatment of choice for most patients. Education, follow-up, and heated humidification may help bolster compliance. Lifestyle modifications, oral appliances, and upper surgeries are additional treatment options.

Two case study reports of sleep apnoea in patients with paraplegia

STUDY DESIGN

Case studies of sleep apnoea occurring in two patients with paraplegia.

OBJECTIVE

To raise awareness of sleep apnoea in paraplegia.

SETTING

Belfast, Northern Ireland.

CASE REPORT

We report two patients with paraplegia, one who was having apparent episodes of loss of consciousness and the other daytime somnolence, who were found to have sleep apnoea. The first patient had been medically investigated extensively and a diagnosis of epilepsy was being considered. A joint consultation with the respective partners in each case revealed periods of night-time apnoea and led to sleep study investigations.

CONCLUSION

Sleep apnoea is a treatable condition that can occur in patients with paraplegia who are not necessarily obese. Once diagnosed, resolution of symptoms can be rapid and can result in improved quality of life for patients.

Continuous positive airway pressure: new generations

Automatic positive airway pressure devices are the most technologically advanced positive airway pressure devices available for use in OSA. Although heterogeneous, they have in common the ability to detect and respond to changes in upper airway resistance. Data cannot necessarily be extrapolated from one device to another, and the field is rapidly advancing. Most studies of APAP have been performed in a supervised setting, or patients have been carefully selected to have a high likelihood of OSA uncomplicated by disorders such as alveolar hypoventilation or central apnea or technical problems such as mask leaks. Studies of APAP for the diagnosis of OSA have shown that APAP can diagnose severe OSA effectively, but the diagnosis of mild-moderate OSA is less reliable. APAP devices also can be effective therapy for selected patients with OSA, with overall similar results to conventional fixed CPAP in terms of respiratory disturbances, sleep quality, nocturnal oxygenation, and daytime sleepiness and performance, with less known or other long-term outcomes. In most studies, mean treatment pressures are lower, without change in side effect profile. Compliance and preference with APAP are similar to or somewhat better than CPAP in most studies. APAP also can be used in an attended setting to titrate an effective pressure for use in long-term conventional CPAP therapy, also with similar results to CPAP in many patients. APAP devices are more expensive than CPAP devices, but the cost may be outweighed if a group of patients who can be diagnosed, treated, or titrated safely in the unattended setting can be identified. Although diagnostic and therapeutic algorithms for APAP have been proposed, the best candidates for this modality must be defined better.

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.

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.

[Prevalence of sleep apnea-hypopnea syndrome among long-haul professional drivers]

Sleep apnea-hypopnea syndrome (SAHS) has been associated with traffic accidents. The aim of this study was to estimate the prevalence of SAHS and analyze risk factors. We studied 163 professional drivers (86.7%) of the 188 employed by 25 participating companies. The subjects completed a questionnaire on SAHS symptoms and risk factors and underwent physical examination and conventional nighttime polysomnographic testing.

RESULTS

The prevalence of an apnea-hypopnea index (AHI) ( 5 was 25.2% (95% CI 18.7-32.5) among the drivers. The prevalence of SAHS was 8.6% (95% CI 3.4-12.1). The prevalence increased with age (p = 0.012). Sleepiness while driving or habitual snoring had a sensitivity of 67.5%, specificity of 62.6% and a positive predictive value of 38.6% for detecting SAHS. Logistic regression modelling showed that the risk factors were a body mass index over 29 kg/m2 (OR: 3.56, 95% CI 1.53-8.4) and sleepiness while driving (OR: 3.7, 95% CI: 1.303-10.3).

CONCLUSION

These results suggest that detecting SAHS among drivers may be useful for preventing traffic accidents; a questionnaire on SAHS symptoms and objective measures such as polysomnography allow cases to be detected and treated.

Prediction formulae for sleep-disordered breathing

Prediction formulae for sleep-disordered breathing can be useful for excluding a diagnosis, establishing an a priori probability of having a positive test, and for prioritizing patient testing. In general, prediction models have high sensitivity but low specificity. In a study analyzing the performance of four previously described prediction models, sensitivities ranged from 76% to 96%, specificities ranged from 13% to 54%, while positive predictive values ranged between 69% and 77%. The models were useful in identifying patients with a respiratory disturbance index of > or = 20 so that these patients could undergo alternative diagnostic testing strategies. The Berlin Questionnaire was tested in primary care settings and was able to identify high-risk patients fairly accurately. A regression neural network performed well with a sensitivity of 99%, a specificity of 80%, a positive predictive value of 88%, and a negative predictive value of 98%. In obese snorers, a regression model utilizing daytime arterial O2 saturation and specific respiratory conductance was effective for excluding obstructive sleep apnea (OSA). In congestive heart failure patients, risk factors for central sleep apnea include male gender, atrial fibrillation, age >60 years, and wake time PaCO2 <38 mm Hg. In children, risk factors for sleep apnea include obesity, African-American race, sinus problems, and persistent wheezing. There are also racial anthropomorphic differences in OSA patients, with whites having a tendency towards brachycephaly facial types (reduced anterior-posterior cranial dimension) and African-Americans having a tendency toward leptoproscopic facial types (longer facial height and decreased facial width). Further refinement of prediction formulae will improve diagnostic accuracy.

Processing and representation of meta-data for sleep apnea diagnosis with an artificial intelligence approach

In this article, we revise and try to resolve some of the problems inherent in questionnaire screening of sleep apnea cases and apnea diagnosis based on attributes which are relevant and reliable. We present a way of learning information about the relevance of the data, comparing this with the definition of the information by the medical expert. We generate a predictive data model using a data aggregation operator which takes relevance and reliability information about the data into account to produce a diagnosis for each case. We also introduce a grade of membership for each question response which allows the patient to indicate a level of confidence or doubt in their own judgement. The method is tested with data collected from patients in a Sleep Clinic using questionnaires specially designed for the study. Other artificial intelligence predictive modeling algorithms are also tested on the same data and their predictive accuracy compared to that of the aggregation operator.