Nightly variability of sleep-disordered breathing measured over 3 nights

Novel oxygen desaturation parameters are associated with cardiac troponin I: Data from the Akershus Sleep Apnea Project

Novel diagnostic markers for obstructive sleep apnea beyond the apnea-hypopnea index (AHI) have been introduced. There are no studies on their association with markers of subclinical myocardial injury. We assessed the association between novel desaturation parameters and elevated cardiac troponin I and T. Participants with polysomnography (498) from the Akershus Sleep Apnea study were divided into normal and elevated biomarker groups based on sex-specific concentration thresholds (cardiac troponin I: ≥4 ng/L for women, ≥6 ng/L for men; and cardiac troponin T: ≥7 ng/L for women, ≥8 ng/L for men). Severity of obstructive sleep apnea was evaluated with the AHI, oxygen desaturation index, total sleep time with oxygen saturation below 90% (T90), lowest oxygen saturation (Min SpO₂ %), and novel oxygen desaturation parameters: desaturation duration and desaturation severity. How the AHI and novel desaturation parameters predicted elevated cardiac troponin I and cardiac troponin T levels was assessed by the area under the curve (AUC). Based on multivariable-adjusted linear regression, the AHI (β = 0.004, p = 0.012), desaturation duration (β = 0.007, p = 0.004), and desaturation severity (β = 0.147, p = 0.002) were associated with cardiac troponin I levels but not cardiac troponin T. T90 was associated with cardiac troponin I (β = 0.006, p = 0.009) and cardiac troponin T (β = 0.005, p = 0.007). The AUC for the AHI 0.592 (standard error 0.043) was not significantly different from the AUC of T90 (SD 0.640, p = 0.08), desaturation duration 0.609 (SD 0.044, p = 0.42) or desaturation severity 0.616 (SD 0.043, p = 0.26) in predicting myocardial injury as assessed by cardiac troponin I. Oxygen desaturation parameters and the AHI were associated with cardiac troponin I levels but not cardiac troponin T levels. Novel oxygen desaturation parameters did not improve the prediction of subclinical myocardial injury compared to the AHI.

Evaluation Parameter of Excessive Daytime Sleepiness for Obstructive Sleep Apnea Patients

Background and Objective Obstructive sleep apnea (OSA) is a sleep-related breathing disorder caused by repetitive obstruction of the upper airway. Repetitive obstruction of the upper airway causes impaired gaseous exchange, resulting hypoxia, hypercapnia, and frequent arousals of sleep architecture. Polysomnography (PSG) is a gold standard for diagnosing OSA. Excessive daytime sleepiness (EDS) is a common accompanying daytime symptoms in OSA patients. Since EDS can cause unexpected events such as traffic accident or poor performance in workplace, it is regarded as a significant public health problem. Therefore, accurate assessment and prediction of this symptom is important. The Epworth Sleepiness Scale (ESS) and multiple sleep latency test are most commonly used to evaluate EDS, but their efficacies are controversial. The purpose of this study is to find the parameter to evaluate and predict the EDS for OSA patients.Methods We retrospectively reviewed the medical records of 88 OSA patients. Patients were divided into two groups according to the presence of EDS. We analyzed the clinical records, questionnaire scores, and PSG data to find the difference between two groups.Results ESS was 10.64 ± 4.28 in EDS patients and 8.63 ± 4.86 in non-EDS patients. ESS showed a statistically significant difference between two groups (p = 0.044). Also, the percentage of 1st stage non-REM sleep in total sleep time (N1%) was 25.09 ± 15.24 in EDS patients and 18.97 ± 10.30 in non-EDS patients and showed a statistically significant difference between groups (p = 0.033). Patients’ weight was 81.59 ± 20.52 in EDS patients and 74.14 ± 12.63 in non-EDS patients and showed a statistically significant difference between groups (p = 0.046).Conclusions ESS, N1% and patients’ weight were significant parameter which is related with the presence of EDS for OSA patients. These parameters will be useful in evaluating the presence of EDS for OSA patients. Also, in patients diagnosed with sleep disorder with high N1%, EDS must be accurately evaluated as well.

Night to night variability of pulse oximetry features in children at home and at the hospital

Objective. Investigation of the night-to-night (NtN) variability of pulse oximetry features in children with suspicion of Sleep Apnea.Approach. Following ethics approval and informed consent, 75 children referred to British Columbia Children's Hospital for overnight PSG were recorded on three consecutive nights, including one at the hospital simultaneously with polysomnography and 2 nights at home. During all three nights, a smartphone-based pulse oximeter sensor was used to record overnight pulse oximetry (SpO2 and photoplethysmogram). Features characterizing SpO2 dynamics and heart rate were derived. The NtN variability of these features over the three different nights was investigated using linear mixed models.Main results. Overall most pulse oximetry features (e.g. the oxygen desaturation index) showed no NtN variability. One of the exceptions is for the signal quality, which was significantly lower during at home measurements compared to measurements in the hospital.Significance. At home pulse oximetry screening shows an increasing predictive value to investigate obstructive sleep apnea (OSA) severity. Hospital recordings affect subjects normal sleep and OSA severity and recordings may vary between nights at home. Before establishing the role of home monitoring as a diagnostic test for OSA, we must first determine their NtN variability. Most pulse oximetry features showed no significant NtN variability and could therefore be used in future at-home testing to create a reliable and consistent OSA screening tool. A single night recording at home should be able to characterize pulse oximetry features in children.

Night-to-night variability of sleep apnea detected by cyclic variation of heart rate during long-term continuous ECG monitoring

Background

Sleep apnea is common in patients with cardiovascular disease and is a factor that worsens prognosis. Holter 24‐h ECG screening for sleep apnea is beneficial in the care of these patients, but due to high night‐to‐night variability of sleep apnea, it can lead to misdiagnosis and misclassification of disease severity.

Methods

To investigate the long‐term dynamic behavior of sleep apnea, seven‐day ECGs recorded with a patch ECG recorder in 120 patients were analyzed for the cyclic variation of heart rate (CVHR) during sleep periods as determined by a built‐in three‐axis accelerometer.

Results

The frequency of CVHR (Fcv) showed considerable night‐to‐night variability (coefficient of variance, 66 ± 35%), which was consistent with the night‐to‐night variability in apnea‐hypopnea index and oxygen desaturation index reported in earlier studies. In patients with presumed moderate‐to‐severe sleep apnea (Fcv > 15 cph at least one night), it was missed on 62% of nights, and on at least one night in 88% of patients. The CV of Fcv was negatively correlated with the average of Fcv, suggesting that patients with mild sleep apnea show greater night‐to‐night variability and would benefit from long‐term assessment. The average Fcv was higher in the supine position, but the night‐to‐night variability was not explained by the night‐to‐night variability of time spent in the supine position.

Conclusions

CVHR analysis of long‐term ambulatory ECG recordings is useful for improving the reliability of screening for sleep apnea without placing an extra burden on patients with cardiovascular disease and their care.

Night-to-night variability in obstructive sleep apnea using peripheral arterial tonometry: a case for multiple night testing

STUDY OBJECTIVES

Night-to-night variability of obstructive sleep apnea severity (OSA) is considerable and may depend on the diagnostic modality used. We investigated the night-to-night variability using peripheral arterial tonometry (PAT).

METHODS

Home sleep apnea testing was performed in 51 patients during three consecutive nights using PAT. Patients referred to our sleep clinic were screened and prospectively recruited for this study. All recordings were automatically and manually scored according to the PAT scoring guidelines.

RESULTS

No systematic differences in pAHI were found between the nights. The night-to-night variability was comparable between manually and automatically scored data. PAT-derived apnea-hypopnea index (pAHI) varied in 35% of patients more than 10/h between the nights. The OSA severity of 24% of patients was misclassified when using one night compared to the average of all nights. On average, pAHI varied by 57% from night-to-night. The variability of pAHI could partially be explained by the variability of time spent in the supine position with more time supine leading to a higher pAHI. On measuring a subsequent night, 12-14% of patients spontaneously fulfilled the commonly accepted criteria for treatment success without any intervention.

CONCLUSIONS

With repeated recordings of PAT, we found no first night effect. However, there is considerable night-to-night variability similar to values found for polysomnography, which can partially be explained by the variability of time spent in the supine position. OSA severity was frequently misclassified due to the night-to-night variability. Our findings make a strong case for multiple testing in the diagnostic work-up of OSA patients.

Night-to-night variability of respiratory events in obstructive sleep apnoea: a systematic review and meta-analysis

Background

It is current practice to use a single diagnostic sleep study in the diagnostic workup of obstructive sleep apnoea (OSA). However, a relevant night-to-night variability (NtNV) of respiratory events has been reported.

Methods

We evaluated the NtNV of respiratory events in adults with suspected or already diagnosed OSA who underwent more than one diagnostic sleep study. Data sources were PubMed, Cochrane and Embase up to 23 January 2019. Random-effects models were used for evidence synthesis. For moderator analysis, mixed-effects regression analysis was performed. The study was registered with PROSPERO (CRD42019135277).

Results

Of 2143 identified papers, 24 studies, comprising 3250 participants, were included. The mean Apnoea-Hypopnoea Index (AHI) difference between the first and second night was −1.70/hour (95% CI −3.61 to 0.02). REM time differences (first to second night) were significantly positive associated with differences in mean AHI (β coefficient 0.262 (95% CI 0.096 to 0.428). On average, 41% (95% CI 27% to 57%) of all participants showed changes of respiratory events >10/hour from night to night. Furthermore, 49% (95% CI 32% to 65%) of participants changed OSA severity class (severity thresholds at 5/hour, 15/hour and 30/hour) at least once in sequential sleep studies. Depending on the diagnostic threshold (5/hour, 10/hour or 15/hour), on average 12% (95% CI 9% to 15%), 12% (95% CI 8% to 19%) and 10% (95% CI 8% to 13%) of patients would have been missed during the first night due to single night testing.

Conclusion

While there was no significant difference between mean AHI in two sequential study nights on a group level, there was a remarkable intraindividual NtNV of respiratory events, leading to misdiagnosis and misclassification of patients with suspected OSA.

High-flow nasal cannula ventilation therapy for obstructive sleep apnea in ischemic stroke patients requiring nasogastric tube feeding: a preliminary study

Obstructive sleep apnea (OSA) is associated with increasing risk of recurrent stroke and mortality. Nasogastric tubes used by dysphagic stroke patients may interfere with nasal continuous positive airway pressure (CPAP) due to air leakage. This study was evaluated the effects and short-term tolerability of high-flow nasal cannula (HFNC) therapy for OSA in stroke patients with nasogastric intubation. The HFNC titration study was performed in post-acute ischemic stroke patients with nasogastric intubation and OSA. Then, participants were treated with HFNC therapy in the ward for one week. Eleven participants (eight males) who were all elderly with a median age of 72 (IQR 67-82) years and a body mass index of 23.5 (IQR 22.0-26.6) completed the titration study. The HFNC therapy at a flow rate up to 50~60 L/min significantly decreased the apnea-hypopnea index from 52.0 events/h (IQR 29.9-61.9) to 26.5 events/h (IQR 3.3-34.6) and the total arousal index from 34.6 (IQR 18.6-42.3) to 15.0 (IQR 10.3-25.4). The oxygen desaturation index was also significantly decreased from 53.0 events/h (IQR 37.0-72.8) to 16.2 events/h (IQR 0.8-20.1), accompanied by a significant improvement in the minimum SpO2 level. Finally, only three participants tolerated flow rates of 50~60 L/minute in one-week treatment period. Conclusively, HFNC therapy at therapeutic flow rate is effective at reducing the OSA severity in post-acute ischemic stroke patients with nasogastric intubation. Owing to the suboptimal acceptance, HFNC might be a temporary treatment option, and CPAP therapy is suggested after the nasogastric tube is removed.

Long-term variability of the apnea-hypopnea index in a patient with mild to moderate obstructive sleep apnea

None

Night-to-night variability (NNV) of the degree of obstructive sleep apnea (OSA) over the long term is not well investigated. In our case, we investigated the NNV of the apnea-hypopnea index (AHI) with regard to sleep structure. Unattended polysomnography (PSG) at home was used to determine the AHI in the course of 4 weeks in a single patient with a mild-to-moderate OSA, by using the Somnocheck R&K system. The mean sleep period was 6.7 ± 1.1 hours and the mean AHI was 14.1 ± 5.7 events/h (range: 5.1-28.3 events/h; coefficient variability [CV] 40.4%). Independent of non-rapid eye movement and rapid eye movement (REM) sleep, the AHI in supine position (43.6 ± 16.9 events/h; CV 38.8%) was greater than during lateral-recumbent sleep (4.8 ± 4.1 events/h; CV 85.4%, P < .0001). A negative correlation was found for both: the AHI in supine position with the duration of supine position sleep (r = .59, P < .001), as well as the AHI in REM with the duration of REM sleep (r = -.37, P < .025). The AHI shows no rhythmicity neither from day to day nor from week to week. We found a high long-term NNV of the AHI, which was typically not influenced by the particular day of the week. Supine AHI is evidently dependent on the duration spent in that position throughout the night. We found it advisable to consider the existence of NNV in association with the degree of OSA, especially for patients with questionable therapeutic indication.

Tonsil size and outcome of uvulopalatopharyngoplasty with tonsillectomy in obstructive sleep apnea

OBJECTIVES/HYPOTHESIS

To investigate the relationship of tonsil volume and grade on outcomes of uvulopalatopharyngoplasty (UPPP) with tonsillectomy in patients with obstructive sleep apnea (OSA).

STUDY DESIGN

Retrospective cohort analysis.

METHODS

Data of 70 consecutive patients undergoing UPPP with tonsillectomy between 2015 and 2018 were analyzed. Patients with an apnea-hypopnea index (AHI) <10/hr or concomitant surgery other than nasal surgery were excluded. Tonsil volume was measured intraoperatively. Preoperatively and 3 months after surgery we assessed the AHI using respiratory polygraphy, daytime sleepiness using the Epworth Sleepiness Scale (ESS), and a visual analog scale for the snoring index (SI).

RESULTS

Tonsil grade and volume both showed a significant correlation with preoperative AHI. Postoperative AHI was not significantly different between grades and volume. The AHI reduction after surgery increased significantly with larger volume and higher tonsil grade. For all grades, the postoperative ESS was significantly reduced compared to the preoperative value, but was not significantly correlated with tonsil volume. Preoperative and postoperative SI was not significantly correlated between tonsil grade or volume. In all grades, SI was significantly reduced after surgery.

CONCLUSIONS

In our study, we found that large tonsils are responsible for higher preoperative AHI values, and their removal leads to greater reduction of initial AHI. However, the postoperative effect on daytime sleepiness and snoring reduction is not significantly correlated with tonsil size and volume, indicating that these parameters are mainly influenced by other factors. The knowledge of the significance of tonsil size and volume is important for ear, nose, and throat physicians when counseling OSA patients.

LEVEL OF EVIDENCE

2c Laryngoscope, 129:E449-E454, 2019.

Reduction in Parasympathetic Tone During Sleep in Children With Habitual Snoring

Introduction: Changes in the autonomic nervous system due to Obstructive Sleep Apnea (OSA) during the life span have been described. Some pediatric studies have shown cardiovascular effects in children who do not fit the criteria for OSA; namely children with mild sleep disordered breathing. Objective: We investigated heart rate variability (HRV) during sleep in children with chronic snoring and flow limitation events during sleep. Methods: Ten children and adolescents with chronic snoring and an apnea hypopnea index < 1, associated to high Respiratory Index, and 10 controls matched for age, gender, and Tanner stage were monitored following one night of habituation in the sleep laboratory. HRV was studied at each sleep stage. The time and frequency domains were calculated for each 5-min period. Results: All patients were chronic heavy snorers. They presented an apnea hypopnea index = 0.8, respiratory disturbance index = 10.2/h with lowest O2 saturation 96.1 ± 2.4%. The total power of HRV was decreased in all stages (p < 0.05). There was also a decrease in NN50 and pNN50 during all sleep stages compared to healthy controls (p = 0.0003 and p = 0.03, respectively). Conclusion: A reduction in parasympathetic tone was found in the patient group. This may represent an autonomic impairment during sleep in children with mild SDB. A reduction in HRV in children with habitual snoring could be associated with possible increases in cardiovascular risk in adulthood. Significance: The study indicates that children with habitual snoring have important parasympathetic tone changes during sleep.

Predicting the night-to-night variability in the severity of obstructive sleep apnea: the case of the standard error of measurement

Study objectives

Night-to-night variability in the apnea-hypopnea index (AHI) may affect the accuracy of the diagnosis of obstructive sleep apnea (OSA) and treatment selection. This study was conducted to assess the utility of the standard error of measurement (SEM) in predicting the night-to-night variability in the OSA.

Methods

Ninety nine patients underwent a 3-consecutive nights of sleep monitoring with a validated home portable monitoring devise (BTI-APNiA, BTI Biotechnology Institute, Vitoria, Spain). The night-to-night variability in apnea- and hypopnea-related measures and blood desaturation were assessed. The agreement between the three nights was also assessed. The SEM and the AHI of the first night were used to calculate a range for the severity of the OSA. This range was then challenged to predict the most frequent OSA severity, the OSA severity in nights 2 and 3, and the OSA severity in the three nights.

Results

Ninety nine patients (mean age: 56±14 years) participated in the study. The mean body mass index was 25.4±4.0 Kg/m² and the mean score of Epworth questionnaire was 8±5. The AHI of the first, second and third nights were 13.96±13.46, 13.76±12.76 and 13.52±12.91 events/h, respectively. The night-to-night variability in the AHI and the sleep time in supine position over the three nights were not statistically significant. However, the differences in the severity of the OSA was statistically significant (range of agreement in the diagnosis: 41.7%-83.3%). The standard error of measurement (SEM) considering the AHI was 4.64 events/h.. The SEM was efficient in predicting the most frequent OSA severity (among the three nights) in more than 96% of the cases.

Conclusions

The night-to-night variability in the AHI might affect the diagnosis of OSA. The use of standard error of measurement and the AHI of one single night would be of interest to predict the night-to-night variability in the severity of OSA.

A validation study on three screening questionnaires for obstructive sleep apnea in a Korean community sample

PURPOSE

Obstructive sleep apnea (OSA) is highly prevalent and causes serious cardiovascular complications. Several screening questionnaires for OSA have been introduced, but only few validation studies have been conducted in general population. The aim of the present study was to assess the diagnostic value of three OSA screening questionnaires (Berlin Questionnaire, BQ; STOP-Bang Questionnaire, STOP-B; Four-Variable Screening Tool, Four-V) in a Korean community sample.

METHODS

A total of 1148 community-dwelling participants completed the BQ, STOP-B, and Four-V. An overnight in-laboratory polysomnography (PSG) was conducted in randomly selected 116 participants. Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio, and area under the curve (AUC) were calculated.

RESULTS

The Four-V with cutoff ≥ 8 showed high sensitivity for overall OSA (69.4%), and the Four-V with cutoff ≥ 9 showed high specificity for both overall OSA (81.5%) and moderate to severe OSA (69.0%). On the other hand, the STOP-B showed acceptable sensitivity and specificity for both overall OSA (61.3 and 79.6%, respectively) and moderate to severe OSA (72.4 and 67.8%, respectively). The STOP-Bang also showed the largest area under the receiver-operator characteristic curve for both overall OSA (0.752) and moderate to severe OSA (0.750). The BQ showed the lowest performance in predicting OSA.

CONCLUSIONS

Among the three questionnaires, the STOP-B was revealed as the most useful screening tool for OSA in terms of sensitivity, specificity, and area under the receiver-operator characteristic curve in the population of South Korea.

Night to night pulse oximetry variability in children with suspected sleep apnea

Obstructive Sleep Apnea (OSA) is the most common form of sleep-disordered breathing in children. The gold standard to screen for OSA, polysomnography (PSG), requires an overnight stay in the hospital and is resource intensive. The Phone Oximeter is a non-invasive smartphone-based tool to record pulse oximetry. This portable device is able to measure patients over multiple nights while at home, causing less sleep disturbance than PSG and is able to measure night to night variability in sleep. This study analyzed the Screen My Sleep children (SMS) dataset, in which 74 children were monitored over multiple nights with the Phone Oximeter, including one night simultaneously with PSG in the hospital and two nights at home. In this study, we aim to investigate the night to night variability and assess the accuracy of the oxygen desaturation index (ODI) screening for children with significant OSA. In order to assess the performance of the ODI calculation in children, we implemented different ODIs at different desaturation levels and time durations. The variability was studied using a one-way ANOVA, and ODI's performance screening for OSA using the area under the ROC curve (AUC). The implemented ODIs provide similar OSA screening results, using different apnea/hypopnea index (AHI) thresholds, as the ODI recommended for adults by the American academy of sleep medicine (AASM). The ODI provides an AUC of around 0.77, 0.76, 0.94 and 0.97 classifying children with an AHI > 1, AHI > 5 AHI > 10 and AHI > 15, respectively. The SMS dataset shows no significant night to night variability between the two nights at home. However, when comparing with the night at the hospital, both nights at home show a decrease in the lowest SpO₂ value as well as overall SpO₂ signal quality percentage. This study shows that there is variability in SpO₂ signal between at-home versus in hospital settings.

A weight-independent association between atypical antipsychotic medications and obstructive sleep apnea

BACKGROUND

With increasing use of atypical antipsychotic (AAP) agents, the concern has been raised about the association between AAP agents and medical complications. Obstructive sleep apnea (OSA) is a common breathing disorder that adversely affects health and quality of life. Because the major risk factors for OSA are weight gain and obesity by altering the upper airway anatomy, an association between AAP and development of OSA is predictable. However, we hypothesized that AAP may promote OSA not only by weight gain but also because of its potential effects on upper airway muscle function. In the present study, we evaluated the possible association between AAP use and the severity of OSA.

METHODS

A sample of patients using AAP for treatment of paradoxical insomnia was evaluated before and at least 8 weeks after AAP use. Patients were divided based on type of AAP use to olanzapine, risperidone, and quetiapine groups. Patients used olanzapine (5-10 mg), risperidone (2-4 mg), or quetiapine (100-200 mg) 2 h before bedtime. Before and after treatment, respiratory variables were recorded using polysomnography. BMI, neck circumference (NC), and waist circumference (WC) were measured before and after treatment period.

RESULTS

There was no significant difference between pre- and post-treatment apnea index (0.2 ± 0.6 vs. 2.6 ± 4.3; p = 0.094) in olanzapine group. However, significant differences in hypopnea index (5.1 ± 5 vs. 30 ± 10.8; p < 0.0001) and AHI (5.3 ± 4.9 vs. 32.6 ± 9.6; p < 0.0001) were observed. Similar results were found in quetiapine and risperidone groups, except that in quetiapine group, apnea index was significantly increased after treatment period (0.7 ± 1.2 in pre-treatment vs. 3.1 ± 2.4 in post-treatment; p = 0.007). There were no significant changes in BMI, NC, and WC during treatment period in all three groups.

CONCLUSION

While AAP medications are known cause of weight gain as a main risk factor of OSA, our finding demonstrated a weight-independent association between AAP medications and worsening respiration during sleep.

Big data in sleep medicine: prospects and pitfalls in phenotyping

Clinical polysomnography (PSG) databases are a rich resource in the era of "big data" analytics. We explore the uses and potential pitfalls of clinical data mining of PSG using statistical principles and analysis of clinical data from our sleep center. We performed retrospective analysis of self-reported and objective PSG data from adults who underwent overnight PSG (diagnostic tests, n=1835). Self-reported symptoms overlapped markedly between the two most common categories, insomnia and sleep apnea, with the majority reporting symptoms of both disorders. Standard clinical metrics routinely reported on objective data were analyzed for basic properties (missing values, distributions), pairwise correlations, and descriptive phenotyping. Of 41 continuous variables, including clinical and PSG derived, none passed testing for normality. Objective findings of sleep apnea and periodic limb movements were common, with 51% having an apnea-hypopnea index (AHI) >5 per hour and 25% having a leg movement index >15 per hour. Different visualization methods are shown for common variables to explore population distributions. Phenotyping methods based on clinical databases are discussed for sleep architecture, sleep apnea, and insomnia. Inferential pitfalls are discussed using the current dataset and case examples from the literature. The increasing availability of clinical databases for large-scale analytics holds important promise in sleep medicine, especially as it becomes increasingly important to demonstrate the utility of clinical testing methods in management of sleep disorders. Awareness of the strengths, as well as caution regarding the limitations, will maximize the productive use of big data analytics in sleep medicine.

Association of sleep time in supine position with apnea-hypopnea index as evidenced by successive polysomnography

PURPOSE

The purpose of this study is to evaluate the impact of body position during sleep on apnea-hypopnea index (AHI) and night-to-night variability in polysomnography (PSG) parameters.

METHODS

Totally, 30 patients with obstructive sleep apnea syndrome (OSAS) were assessed prospectively with successive PSGs performed. The patients were categorized as increased (group A), decreased (group B), and unchanged (group C) AHI between the first and second PSG evaluations performed at least 1-week interval.

RESULTS

The mean AHI values were significantly higher in the second night (p = 0.02). A change in AHI was found in almost 85 % of the patients between two successive measurements. According to multivariate and correlation analyses and differences in total AHI in supine position (r = 0.897), it was found that the influence of the supine position was the primary factor contributing to the night-to-night variability. Supine AHI, non-supine AHI, and non-supine time findings did not add any significance on total AHI.

CONCLUSIONS

The variability observed in the AHI seems related to amount of sleeping time spent in supine position, suggesting that mean AHI alone is not that reliable in the accurate diagnosis of OSAS severity. A thorough evaluation of AHI in supine and non-supine positions is needed in order to understand better the severity of OSAS.

Short-Term Variability in Apnea-Hypopnea Index during Extended Home Portable Monitoring

STUDY OBJECTIVES

Apnea-hypopnea index (AHI) is the primary measure used to confirm a diagnosis of obstructive sleep apnea (OSA). However, there may be significant night-to-night variability (NNV) in AHI, limiting the value of AHI in clinical decision-making related to OSA management. We examined short-term NNV in AHI and its predictors during home portable monitoring (PM).

METHODS

Single center prospective observational study of patients (n = 84) with newly diagnosed OSA by polysomnography (PSG) AHI ≥ 5/h. All participants underwent 2 to 8 consecutive nights of PM.

RESULTS

Participants (n = 84) were middle-aged (47 ± 8.3 y, mean ± standard deviation; SD), including 28 women, with mean AHI on baseline PSG (AHIPSG) of 30.1 ± 31.8. Mean AHI on PM (AHIPM) was 27.4 ± 23.7. Intraclass correlation coefficient (ICC) for AHIPM in the entire sample was 0.73 (95% CI 0.66-0.8), indicating that 27% of the variability in AHIPM was due to intra-individual factors. Mild severity of OSA, defined by AHIPSG 5-15/h, was associated with higher NNV (likelihood ratio, -0.4 ± 0.14; p = 0.006) and absence of comorbidity showed a trend towards higher NNV (-0.54 ± 0.27, p = 0.05) on AHIPM.

CONCLUSIONS

The intraindividual short-term NNV in AHIPM is higher in mild versus moderately severe OSA, even in the home setting, where first-night effect is not expected. Larger studies of NNV focused on patients with mild OSA are needed to identify characteristics that predict need and timing for repeated diagnostic testing and treatment.

COMMENTARY

A commentary on this article appears in this issue on page 787.

Snoring Significance in Patients Undergoing Home Sleep Studies

OBJECTIVE: To analyze the impact of snoring, independent of obstructive sleep apnea syndrome on patients referred for home sleep studies and to report a new technology for the reporting of snoring, using sophisticated sound collection and noise-canceling technology.

STUDY DESIGN AND SETTING: A retrospective statistical review of consecutive anonymous data compiled from questionnaires and digital data of snoring loudness and duration measured at the upper lip during unattended home sleep studies in 4,860 patients referred for snoring and sleep-disturbed breathing.

RESULTS: A strong relationship exists between a history of snoring and complaints of daytime sleepiness (80%), obesity (73%), and chronic fatigue (78%) (all yield P < 0.001). By contrast, only 42% to 48% of patients without these symptoms complain of snoring. In 3 multiple-regression analyses, the percent of time snoring, average loudness, and peak loudness are all significantly predicted by the apnea hypopnea index (all P < 0.003), body mass index (all P < 0.001), and age ( P = 0.014). Daytime sleepiness was strongly predicted by percent time snoring ( P = 0.014), weakly by average loudness ( P = 0.046), and not at all by peak loudness (P = 0.303).

CONCLUSION: By using a pair of microphones placed at the upper lip, one that samples breath sounds and the other ambient sound and artifact noise, the NovaSOM QSG measures snoring while canceling ambient noise. The clinical impact of snoring on the patient as well as the bed partner, independent of obstructive sleep apnea syndrome, is an unrecognized factor in sleep-disturbed breathing.

SIGNIFICANCE: Measurable criteria to define snoring are suggested. Snoring loudness is not measured in most laboratory Polysomnograms.

EBM rating: B-3b

Soft Palate Implants for the Treatment of Mild to Moderate Obstructive Sleep Apnea

OBJECTIVE: To evaluate the initial short-term effectiveness of palatal implants in treating patients with mild to moderate obstructive sleep apnea (OSA). Previous published studies have focused on snoring without OSA.

STUDY DESIGN: A prospective, nonrandomized study of 25 previously untreated patients with an apnea-hypopnea index (AHI) of 10 to 30 and a body mass index (BMI) of ≤30. Three permanent implants (Pillar; Restore Medical, St Paul, MN) were placed in the soft palate of each patient with a specially designed delivery tool in an office setting under local anesthesia after a formal polysomnography. A repeat polysomnography was obtained after 90 days.

RESULTS: The AHI was reduced from a mean of 16.2 to a mean of 12.1 (P < 0.05) for the study group. Twenty of 25 patients (80%) experienced a decrease in the AHI. Twelve of 25 patients (48%) showed a post-90-day implant AHI of 10 or less, a benchmark for the possible cessation of continuous positive airway pressure therapy. The Epworth Sleepiness Score decreased from 9.7 to 5.5 ( P < 0.001) and the visual analog Scale of snoring intensity reported by bed partners decreased from 8.4 to 4.3 ( P < 0.001).

CONCLUSION: The palatal implant method can significantly improve AHI and other sleep-related parameters in patients with mild to moderate OSA and a BMI of ≤30. Short-term results are comparative to those reported for uvulopalatopharyngoplasty but achieved in a low-cost, single-stage, outpatient office setting with low morbidity.

Utility of portable monitoring in the diagnosis of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common but underdiagnosed sleep disorder, which is associated with systemic consequences such as hypertension, stroke, metabolic syndrome, and ischemic heart disease. Nocturnal laboratory-based polysomnography (PSG) is the gold standard test for diagnosis of OSA. PSG consists of a simultaneous recording of multiple physiologic parameters related to sleep and wakefulness including electroencephalography (EEG), electrooculography (EOG), surface electromyography (EMG), airflow measurement using thermistor and nasal pressure transducer, pulse oximetry and respiratory effort (thoracic and abdominal). Multiple alternative and simpler methods that record respiratory parameters alone for diagnosing OSA have been developed in the past two decades. These devices are called portable monitors (PMs) and enable performing sleep studies at a lower cost with shorter waiting times. It has been observed and reported that comprehensive sleep evaluation coupled with the use of PMs can fulfill the unmet need for diagnostic testing in various out-of-hospital settings in patients with suspected OSA. This article reviews the available medical literature on PMs in order to justify the utility of PMs in the diagnosis of OSA, especially in resource-poor, high-disease burden settings. The published practice parameters for the use of these devices have also been reviewed with respect to their relevance in the Indian setting.

Predictors of Obstructive Sleep Apnea on Polysomnography after a Technically Inadequate or Normal Home Sleep Test

STUDY OBJECTIVES

Home sleep testing (HST) is an accepted alternative to polysomnography (PSG) for diagnosing obstructive sleep apnea (OSA) in high-risk populations. Clinical guidelines recommend PSG in cases where the HST is technically inadequate (TI) or fails to establish the diagnosis of OSA in patients with high pretest probability. This retrospective study evaluated predictors of OSA on PSG within patients who had a TI or normal HST.

METHODS

Electronic medical records were reviewed on 1,157 patients referred for HST at our sleep center. Two hundred thirty-eight patients had a TI or normal HST with subsequent PSG. Age, BMI, Epworth score, HST result, and PSG-based apnea-hypopnea index (AHI) were abstracted.

RESULTS

Two hundred thirty-eight consecutive patients with either a normal HST (n = 127) or TI HST (n = 111) underwent subsequent PSG. Of 127 who had a normal HST, 76% had a normal PSG and 24% had OSA (23 mild, 6 moderate, 1 severe). Of 111 who had a TI HST, 29% had a normal PSG and 71% had OSA (43 mild, 19 moderate, 17 severe). Individuals younger than 50 years old with a normal HST were more likely to have a normal PSG. Older age predicted diagnosis of OSA on PSG among individuals with a TI HST.

CONCLUSION

In this retrospective analysis of a clinical sample, when the HST is interpreted as normal in a younger patient population, the subsequent PSG is likewise normal in majority of the patients, although significant OSA is sometimes discovered. When a HST is read as TI, the majority of patients have OSA.

Type III home sleep testing versus pulse oximetry: is the respiratory disturbance index better than the oxygen desaturation index to predict the apnoea-hypopnoea index measured during laboratory polysomnography?

OBJECTIVES

In its guidelines on the use of portable monitors to diagnose obstructive sleep apnoea, the American Academy of Sleep Medicine endorses home polygraphy with type III devices recording at a minimum airflow the respiratory effort and pulse oximetry, but advises against simple pulse oximetry. However, oximetry is widely available and simple to use in the home. This study was designed to compare the ability of the oxygen desaturation index (ODI) based on oximetry alone with a stand-alone pulse oximeter (SPO) and from the oximetry channel of the ApneaLink Plus (ALP), with the respiratory disturbance index (RDI) based on four channels from the ALP to predict the apnoea-hypopnoea index (AHI) from laboratory polysomnography.

DESIGN

Cross-sectional diagnostic accuracy study.

SETTING

Sleep medicine practice of a multispecialty clinic.

PARTICIPANTS

Patients referred for laboratory polysomnography with suspected sleep apnoea. We enrolled 135 participants with 123 attempting the home sleep testing and 73 having at least 4 hours of satisfactory data from SPO and ALP.

INTERVENTIONS

Participants had home testing performed simultaneously with both a SPO and an ALP. The 2 oximeter probes were worn on different fingers of the same hand. The ODI for the SPO was calculated using Profox software (ODI(SOX)). For the ALP, RDI and ODI were calculated using both technician scoring (RDI(MAN) and ODI(MAN)) and the ALP computer scoring (RDI(RAW) and ODI(RAW)).

RESULTS

The receiver-operator characteristic areas under the curve for AHI ≥ 5 were RDI(MAN) 0.88 (95% confidence limits 0.81-0.96), RDI(RAW) 0.86 (0.76-0.94), ODI(MAN) 0.86 (0.77-0.95), ODI(RAW) 0.84 (0.75-0.93) and ODI(SOX) 0.83 (0.73-0.93).

CONCLUSIONS

We conclude that the RDI and the ODI, measured at home on the same night, give similar predictions of the laboratory AHI, measured on a different night. The differences between the two methods are small compared with the reported night-to-night variation of the AHI.

Reliability of SleepStrip as a screening test in obstructive sleep apnea patients

Obstructive sleep apnea syndrome (OSAS) is a common sleep disorder and related to multiple conditions that cause mortality in adults. In the present study, reliability of SleepStrip, a disposable screening device for detection of OSAS, is tested. In this prospective, nonrandomized double-blinded single cohort study at an academic health center, the performance of the SleepStrip in detecting respiratory events and establishing an SleepStrip score (Sscore) in domestic use were compared to the apnea-hypopnea index (AHI) obtained by the standard polysomnography (PSG) recordings in the sleep laboratory. Forty-one patients who have the PSG results participated the study and wore the SleepStrips at home. Test efficiency rate was 75% and there was a positive correlation between PSG-AHI scores and Sscores (r = 0.71, p < 0.001). However, diagnostic accuracy analysis showed that the correlation between Sscores and PSG-AHI scores were significant only at AHI > 30 levels. The SleepStrip has 100% specificity and positive predictive values, but it also has low negative predictive and sensitivity values. The SleepStrip is not a reliable screening test in differential diagnosis among simple snorers, mild, moderate and severe OSAS patients. However, high Sscores highly indicate the presence of moderate-severe OSAS. We can safely send these patients to split-night PSG and continuous, automatic, bi-level positive airway pressure (CPAP/BPAP/APAP) titration at the same night. The SleepStrip may increase the effective use of the sleep laboratories.

Unattended home-based polysomnography for sleep disordered breathing: current concepts and perspectives

Recently, portable sleep recording devices became an accepted alternative to polysomnography (PSG) for obstructive sleep apnea (OSA) diagnosis in patients with a high pre-test probability of moderate to severe OSA but home polysomnography (H-PSG) was not recommended because there were insufficient data. The present review has analysed six prospective randomized crossover studies comparing H-PSG to in-lab PSG. These studies convincingly showed that H-PSG allows complete sleep evaluation. The quality of patients' sleep tends to be better at home. H-PSG is accurate for OSA diagnosis and the failure rate is low despite the absence of supervision. In addition, it could offer a final and comprehensive diagnosis for many other sleep disorders. It is also likely that H-PSG can reduce PSG-related costs but complete cost-effectiveness analyses are not yet available. Recently, remotely attended H-PSG via telemonitoring has been tested and may reduce H-PSG failure rate. In conclusion, H-PSG can be used to rule-in and rule out OSA in suspected patients, even in the presence of co-morbidities and is an alternative when simplified sleep testing is negative. Future developments should target simplification of technical aspects of H-PSG, together with remote monitoring, in order to obtain good quality H-PSG performed in adequate conditions.

Supine position related obstructive sleep apnea in adults: pathogenesis and treatment

The most striking feature of obstructive respiratory events is that they are at their most severe and frequent in the supine sleeping position: indeed, more than half of all obstructive sleep apnea (OSA) patients can be classified as supine related OSA. Existing evidence points to supine related OSA being attributable to unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses. The role of arousal threshold and ventilatory control instability in the supine position has however yet to be defined. Crucially, few physiological studies have examined patients in the lateral and supine positions, so there is little information to elucidate how breathing stability is affected by sleep posture. The mechanisms of supine related OSA can be overcome by the use of continuous positive airway pressure. There are conflicting data on the utility of oral appliances, while the effectiveness of weight loss and nasal expiratory resistance remains unclear. Avoidance of the supine posture is efficacious, but long term compliance data and well powered randomized controlled trials are lacking. The treatment of supine related OSA remains largely ignored in major clinical guidelines. Supine OSA is the dominant phenotype of the OSA syndrome. This review explains why the supine position so favors upper airway collapse and presents the available data on the management of patients with supine related OSA.

Significance of including a surrogate arousal for sleep apnea-hypopnea syndrome diagnosis by respiratory polygraphy

RATIONALE

Respiratory polygraphy is an accepted alternative to polysomnography (PSG) for sleep apnea/hypopnea syndrome (SAHS) diagnosis, although it underestimates the apnea-hypopnea index (AHI) because respiratory polygraphy cannot identify arousals.

OBJECTIVES

We performed a multicentric, randomized, blinded crossover study to determine the agreement between home respiratory polygraphy (HRP) and PSG, and between simultaneous respiratory polygraphy (respiratory polygraphy with PSG) (SimultRP) and PSG by means of 2 AHI scoring protocols with or without hyperventilation following flow reduction considered as a surrogate arousal.

METHODS

We included suspected SAHS patients from 8 hospitals. They were assigned to home and hospital protocols at random. We determined the agreement between respiratory polygraphy AHI and PSG AHI scorings using Bland and Altman plots and diagnostic agreement using receiver operating characteristic (ROC) curves. The agreement in therapeutic decisions (continuous positive airway pressure treatment or not) between HRP and PSG scorings was done with likelihood ratios and post-test probability calculations.

RESULTS

Of 366 randomized patients, 342 completed the protocol. AHI from HRP scorings (with and without surrogate arousal) had similar agreement with PSG. AHI from SimultRP with surrogate arousal scoring had better agreement with PSG than AHI from SimultRP without surrogate arousal. HRP with surrogate arousal scoring had slightly worse ROC curves than HRP without surrogate arousal, and the opposite was true for SimultRP scorings. HRP with surrogate arousal showed slightly better agreement with PSG in therapeutic decisions than for HRP without surrogate arousal.

CONCLUSION

Incorporating a surrogate arousal measure into HRP did not substantially increase its agreement with PSG when compared with the usual procedure (HRP without surrogate arousal).

Obstructive sleep apnea, verbal memory, and executive function in a community-based high-risk population identified by the Berlin Questionnaire Akershus Sleep Apnea Project

PURPOSE

Cognitive functions in community-dwelling adults at high risk of obstructive sleep apnea have not been described and nor are associations between cognitive functions and obstructive sleep apnea severity fully understood. The study aimed to describe verbal memory and executive function in community-dwelling adults identified by the Berlin Questionnaire and to investigate associations between these cognitive domains and different obstructive sleep apnea severity indicators.

METHODS

Among 29,258 age- and gender-stratified persons 30-65 years who received the Berlin Questionnaire by mail, 16,302 (55.7%) responded. From 654 randomly drawn respondents with BQ high risk who were approached for study participation, 290 participants (55.9% males, mean age 48.2 years) were included. Verbal memory was assessed by Rey Auditory Verbal Learning Test and executive function by Stroop test. Obstructive sleep apnea severity indicators were assessed by polysomnography.

RESULTS

Mean (standard deviation) verbal learning score was 42.0 (8.9), mean interference time was 31.1 (12.7), median (25th percentile, 75th percentile) apnea-hypopnea index was 7.7 (2.4-22.2), and mean average oxygen saturation was 94.3 (2.0). Verbal learning score was independently associated with average oxygen saturation (β = 0.721, p = 0.025) in multivariate linear regression models adjusted for putative confounders. Interference time was only related to OSA severity indicators in bivariate analyses.

CONCLUSIONS

Verbal memory and executive function impairments were mild in community-dwelling adults at high risk of obstructive sleep apnea. Average oxygen saturation was the indicator of obstructive sleep apnea severity most strongly associated with cognitive function.

Type 2 diabetes and pre-diabetes are associated with obstructive sleep apnea in extremely obese subjects: a cross-sectional study

Background

Obstructive sleep apnea (OSA) is a common yet underdiagnosed condition. The aim of our study is to test whether prediabetes and type 2 diabetes are associated with obstructive sleep apnea (OSA) in extremely obese (BMI ≥ 40 kg/m²) subjects.

Methods

One hundred and thirty seven consecutive extremely obese patients (99 females) from a controlled clinical trial [MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)] underwent somnography with Embletta^® and a 2-hour oral glucose tolerance test (OGTT). OSA was defined by an apnea-hypopnea index (AHI) ≥ 5 events/hour. Patients were categorized into three groups according to criteria from the American Diabetes Association: normal glucose tolerance, pre-diabetes and type 2 diabetes. Multiple logistic regression analysis was used to identify possible determinants of OSA.

Results

The patients had a mean (SD) age of 43 (11) years and a body mass index (BMI) of 46.9 (5.7) kg/m². Males had significantly higher AHI than females, 29 (25) vs 12 (17) events/hour, p < 0.001. OSA was observed in 81% of men and in 55% of women, p = 0.008. Twenty-nine percent of subjects had normal glucose tolerance, 42% had pre-diabetes and 29% had type 2 diabetes. Among the patients with normal glucose tolerance 33% had OSA, while 67% of the pre-diabetic patients and 78% of the type 2 diabetic patients had OSA, p < 0.001. After adjusting for age, gender, BMI, high sensitive CRP and HOMA-IR, both pre-diabetes and type 2 diabetes were still associated with OSA, odds ratios 3.18 (95% CI 1.00, 10.07), p = 0.049 and 4.17 (1.09, 15.88), p = 0.036, respectively. Mean serum leptin was significantly lower in the OSA than in the non-OSA group, while other measures of inflammation did not differ significantly between groups.

Conclusions

Type 2 diabetes and pre-diabetes are associated with OSA in extremely obese subjects.

Trial registration

MOBIL-study (Morbid Obesity treatment, Bariatric surgery versus Intensive Lifestyle intervention Study) (ClinicalTrials.gov number NCT00273104)

Effect of transnasal insufflation on sleep disordered breathing in acute stroke: a preliminary study

BACKGROUND AND PURPOSE

Sleep disordered breathing (SDB) is frequent in acute stroke patients and is associated with early neurologic worsening and poor outcome. Although continuous positive airway pressure (CPAP) effectively treats SDB, compliance is low. The objective of the present study was to assess the tolerance and the efficacy of a continuous high-flow-rate air administered through an open nasal cannula (transnasal insufflation, TNI), a less-intrusive method, to treat SDB in acute stroke patients.

METHODS

Ten patients (age, 56.8 ± 10.7 years), with SDB ranging from moderate to severe (apnea-hypopnea index, AHI, >15/h of sleep) and on a standard sleep study at a mean of 4.8 ± 3.7 days after ischemic stroke (range, 1-15 days), were selected. The night after, they underwent a second sleep study while receiving TNI (18 L/min).

RESULTS

TNI was well tolerated by all patients. For the entire group, TNI decreased the AHI from 40.4 ± 25.7 to 30.8 ± 25.7/h (p = 0.001) and the oxygen desaturation index >3% from 40.7 ± 28.4 to 31 ± 22.5/h (p = 0.02). All participants except one showed a decrease in AHI. The percentage of slow-wave sleep significantly increased with TNI from 16.7 ± 8.2% to 22.3 ± 7.4% (p = 0.01). There was also a trend toward a reduction in markers of sleep disruption (number of awakenings, arousal index).

CONCLUSIONS

TNI improves SDB indices, and possibly sleep parameters, in stroke patients. Although these changes are modest, our findings suggest that TNI is a viable treatment alternative to CPAP in patients with SDB in the acute phase of ischemic stroke.

Therapeutic decision-making for sleep apnea and hypopnea syndrome using home respiratory polygraphy: a large multicentric study

RATIONALE

Home respiratory polygraphy (HRP) is an alternative to polysomnography (PSG) for sleep apnea-hypopnea syndrome (SAHS) diagnosis. However, therapeutic decision-making is a different process than diagnosis.

OBJECTIVES

This study aimed to determine the agreement between HRP and in-hospital PSG for therapeutic decision-making in a large sample.

METHODS

Patients with an intermediate or high SAHS suspicion were included in a multicenter study (eight sleep centers) and assigned to home and hospital protocols in a random order. Therapeutic decisions (continuous positive airway pressure, no continuous positive airway pressure, or impossible decision) were made by an investigator in each center, based on using either HRP or PSG and a single set of auxiliary clinical variables. Patients and diagnostic methods (HRP and PSG) were assessed in random order using an electronic database. After a month the same therapeutic decision-making procedure was repeated with the same method.

MEASUREMENTS AND MAIN RESULTS

Of 366 randomized patients, 348 completed the protocol. The "impossible decision" case was not observed with either PSG or HRP. Therapeutic decisions using HRP had a sensitivity of 73%, a specificity of 77%, and an agreement level (sum of true positives and negatives) of 76%. Patients with higher HRP apnea-hypopnea index (AHI) scores (≥ 30; 41% of the total sample) had a sensitivity of 94%, a specificity of 44%, and the agreement level was 91%.

CONCLUSIONS

The HRP-based therapeutic decision was adequate when AHI was high, but deficient in the large population of patients with mild to moderate AHI. Therefore, both selecting patients with a high suspicion and severity of SAHS and future prospective cost-effectiveness studies are necessary.

A Norwegian population-based study on the risk and prevalence of obstructive sleep apnea. The Akershus Sleep Apnea Project (ASAP)

The Berlin Questionnaire (BQ) is a widely used screening tool for obstructive sleep apnea (OSA), but its performance in the general population setting is unknown. The prevalence of OSA in middle-aged adults is not known in Norway. Accordingly, the aims of the current study were to evaluate the utility of the BQ for OSA screening in the general population and to estimate the prevalence of OSA in Norway. The study population consisted of 29,258 subjects (aged 30-65 years, 50% female) who received the BQ by mail. Of these, 16,302 (55.7%) responded. Five-hundred and eighteen subjects were included in the clinical sample and underwent in-hospital polysomnography. Screening properties and prevalence were estimated by a statistical model that adjusted for bias in the sampling procedure. Among the 16,302 respondents, 24.3% (95% confidence interval (CI)=23.6-25.0%) were classified by the BQ to be at high-risk of having OSA. Defining OSA as an apnea-hypopnea index (AHI) ≥5, the positive predictive value of the BQ was estimated to be 61.3%, the negative predictive value 66.2%, the sensitivity 37.2% and the specificity 84.0%. Estimated prevalences of OSA were 16% for AHI≥5 and 8% for AHI≥15. In conclusion, the BQ classified one out of four middle-aged Norwegians to be at high-risk of having OSA, but the screening properties of the BQ were suboptimal. The estimated prevalence of OSA was comparable to previous estimates from general populations in the USA, Australia and Europe.

Migraine and sleep apnea in the general population

Objective is to investigate the relationship between migraine and obstructive sleep apnea in the general population. A cross-sectional population-based study. A random age and gender stratified sample of 40,000 persons aged 20-80 years residing in Akershus, Hedmark or Oppland County, Norway, were drawn by the National Population Register. A postal questionnaire containing the Berlin Questionnaire was used to classify respondents to be of either high or low risk of obstructive sleep apnea. 376 persons with high risk and 157 persons with low risk of sleep apnea aged 30-65 years were included for further investigations. They underwent an extensive clinical interview, a physical and a neurological examination by physicians, and in-hospital polysomnography. Those with apnea hypopnoea index (AHI) ≥5 were classified with obstructive sleep apnea. Migraine without aura (MO) and migraine with aura (MA) was diagnosed according to the International Classification of Headache Disorders. MO and MA occurred in 12.5 and 6.8% of the participants with obstructive sleep apnea. The logistic regression analyses showed no relationship between the two types of migraine and obstructive sleep apnea, with adjusted odds ratios for MO 1.15 (0.65-2.06) and MA 1.15 (0.95-2.39). Further, estimates using cutoff of moderate (AHI ≥ 15) and severe (AHI ≥ 30) obstructive sleep apnea, did not reveal any significant relationship between migraine and the AHI. Migraine and obstructive sleep apnea are unrelated in the general population.

Tension-type headache and sleep apnea in the general population

The main objective of this study is to investigate the relationship between tension-type headache and obstructive sleep apnea in the general population. The method involves a cross-sectional population-based study. A random age and gender stratified sample of 40,000 persons aged 20-80 years residing in Akershus, Hedmark or Oppland County, Norway were drawn by the National Population Register. A postal questionnaire containing the Berlin Questionnaire was used to classify respondents to be of either high or low risk of obstructive sleep apnea. Included in this study were 297 persons with high risk and 134 persons with low risk of sleep apnea, aged 30-65 years. They underwent an extensive clinical interview, a physical and a neurological examination by physicians, and in-hospital polysomnography. Those with apnea hypopnoea index (AHI) ≥5 were classified with obstructive sleep apnea. Tension-type headache was diagnosed according to the International Classification of Headache Disorders. Results showed the prevalence of frequent and chronic tension-type headache was 18.7 and 2.1% in the participants with obstructive sleep apnea. The logistic regression analyses showed no significant relationship between tension-type headache and obstructive sleep apnea, with adjusted odds ratios for frequent tension-type headache of 0.95 (0.55-1.62) and chronic tension-type headache of 1.91 (0.37-9.85). The results did not change when using cut-off of moderate (AHI ≥15) and severe (AHI ≥30) obstructive sleep apnea. Thus, we did not find any significant relationship between tension-type headache and the AHI. The presence and severity of sleep apneas seem not to influence presence and attack-frequency of tension-type headache in the general population.

Pitot-tube flowmeter for quantification of airflow during sleep

The gold-standard pneumotachograph is not routinely used to quantify airflow during overnight polysomnography due to the size, weight, bulkiness and discomfort of the equipment that must be worn. To overcome these deficiencies that have precluded the use of a pneumotachograph in routine sleep studies, our group developed a lightweight, low dead space 'pitot flowmeter' (based on pitot-tube principle) for use during sleep. We aimed to examine the characteristics and validate the flowmeter for quantifying airflow and detecting hypopneas during polysomnography by performing a head-to-head comparison with a pneumotachograph. Four experimental paradigms were utilized to determine the technical performance characteristics and the clinical usefulness of the pitot flowmeter in a head-to-head comparison with a pneumotachograph. In each study (1-4), the pitot flowmeter was connected in series with a pneumotachograph under either static flow (flow generator inline or on a face model) or dynamic flow (subject breathing via a polyester face model or on a nasal mask) conditions. The technical characteristics of the pitot flowmeter showed that, (1) the airflow resistance ranged from 0.065 ± 0.002 to 0.279 ± 0.004 cm H(2)O L(-1) s(-1) over the airflow rates of 10 to 50 L min(-1). (2) On the polyester face model there was a linear relationship between airflow as measured by the pitot flowmeter output voltage and the calibrated pneumotachograph signal a (β(1) = 1.08 V L(-1) s(-1); β(0) = 2.45 V). The clinically relevant performance characteristics (hypopnea detection) showed that (3) when the pitot flowmeter was connected via a mask to the human face model, both the sensitivity and specificity for detecting a 50% decrease in peak-to-peak airflow amplitude was 99.2%. When tested in sleeping human subjects, (4) the pitot flowmeter signal displayed 94.5% sensitivity and 91.5% specificity for the detection of 50% peak-to-peak reductions in pneumotachograph-measured airflow. Our data validate the pitot flowmeter for quantification of airflow and detecting breathing reduction during polysomnographic sleep studies. We speculate that quantifying airflow during sleep can differentiate phenotypic traits related to sleep disordered breathing.

Predictors for treating obstructive sleep apnea with an open nasal cannula system (transnasal insufflation)

BACKGROUND

Obstructive sleep apnea (OSA) is a disorder that is associated with increased morbidity and mortality. Although continuous positive airway pressure effectively treats OSA, compliance is variable because of the encumbrance of wearing a sealed nasal mask throughout sleep. In a small group of patients, it was recently shown that an open nasal cannula (transnasal insufflation [TNI]) can treat OSA. The aim of this larger study was to find predictors for treatment responses with TNI.

METHODS

Standard sleep studies with and without TNI were performed in 56 patients with a wide spectrum of disease severity. A therapeutic response was defined as a reduction of the respiratory disturbance index (RDI) below 10 events/h associated with a 50% reduction of the event rate from baseline and was used to identify subgroups of patients particularly responsive or resistant to TNI treatment.

RESULTS

For the entire group (N = 56), TNI decreased the RDI from 22.6 +/- 15.6 to 17.2 +/- 13.2 events/h (P < .01). A therapeutic reduction in the RDI was observed in 27% of patients. Treatment responses were similar in patients with a low and a high RDI, but were greater in patients who predominantly had obstructive hypopneas or respiratory effort-related arousals and in patients who predominantly had rapid eye movement (REM) events. The presence of a high percentage of obstructive and central apneas appears to preclude efficacious treatment responses.

CONCLUSION

TNI can be used to treat a subgroup of patients across a spectrum from mild-to-severe sleep apnea, particularly if their sleep-disordered breathing events predominantly consist of obstructive hypopneas or REM-related events but not obstructive and central apneas.

The Berlin questionnaire for sleep apnea in a sleep clinic population: relationship to polysomnographic measurement of respiratory disturbance

The Berlin questionnaire (BQ) has been used to help identify patients at high risk of having sleep apnea in primary care and atrial fibrillation patients. The BQ may be a useful adjunct in sleep medicine and research, but it has never been validated in a sleep clinic population. The aim of the study is to determine the specificity and sensitivity of the BQ compared to the respiratory disturbance index (RDI) values obtained from two nights of polysomnographic recording in a sleep clinic population. This is a retrospective chart review study of 130 sleep clinic patients. Patients' demographics, BQ scores, RDI measurements, and sleep study parameters were extracted from the patients' chart. Of the 130 charts reviewed, the BQ identified 76 (58.5%) as being at high-risk of having sleep apnea, but overnight polysomnography found only 34 of the 130 patients (26.2%) had an RDI > 10. The BQ performed with 0.62 sensitivity and 0.43 specificity at the RDI > 10 level. Due to the low sensitivity and specificity as well as the large number of false negatives and positives, the Berlin questionnaire is not an appropriate instrument for identifying patients with sleep apnea in a sleep clinic population.

Clinical diagnosis of sleep apnea based on single night of polysomnography vs. two nights of polysomnography

PURPOSE

The purpose of this study was to investigate apnea-hypopnea index (AHI) across two polysomnographies (PSGs) to examine AHI variability and impact on clinical diagnosis.

MATERIALS AND METHODS

Two-night PSGs of 193 sleep clinic patients were reviewed, and the AHI variability was analyzed. Anonymized records from five patients with significant night-to-night AHI variability were used in this study: the two-night PSGs from two patients were represented as four individual PSGs; the two-night PSG for two others were represented as being obtained from two different sleep clinics; the last patient's PSG was shown as a two-night study. Twenty-two sleep experts attending the Associated Professional Sleep Societies meeting were recruited to make diagnoses based on the PSGs. They were told that the PSGs were from seven patients: four with single-night PSG; two with two PSGs, each one from a different clinic; and one patient with a two-night PSG.

RESULTS

Twenty-one percent of the 193 sleep clinic patients had a nightly PSG AHI variability of greater than 5. Forty-eight percent of all patients had a significantly higher AHI on the first night, and 41% had a significantly higher AHI on the second night. Using an AHI > 15 diagnostic criteria, sleep apnea would have been undetected in 20% (n = 39) of patients due to low AHI on one night. Furthermore, 13% of all patients had a more severe sleep apnea classification based on the second night of PSG. For the seven cases, 27-36% of sleep experts failed to identify sleep apnea especially when presented with the PSG containing the lower AHI. Incidences of missed sleep apnea diagnoses were reduced to 15-18% when information from two PSGs was presented to the sleep experts.

CONCLUSIONS

Utilizing a large patient population, this study supports the significant night-to-night variability in PSG respiratory variables. Identification of sleep apnea in some patients is reduced when sleep experts are provided with only one PSG recording. The clinical implication is that about 13% of sleep clinic patients might benefit from a second night of PSG.

Low night-to-night variability of sleep disordered breathing in patients with stable congestive heart failure

Sleep disordered breathing (SDB) has a high prevalence and prognostic impact in patients with chronic heart failure (CHF). Aim of this study was to investigate variability of SDB parameters in patients with stable CHF. Cardiorespiratory polygraphy was used to determine SDB in two consecutive nights in 50 CHF patients (NYHA class > or = II, LV-EF < or = 40%). The apnea-hypopnea-index (AHI) and apnoea-index (AI) were used to quantify SDB severity. Central, obstructive or mixed SDB were classified according to the majority of events. There was an excellent correlation in AHI (r = 0.948, P < 0.001) and AI (r = 0.842, P < 0.001) results of both nights. The overall number of detected apnea and hypopnea during the first night as compared to the maximum of both nights was 85% for the AHI and 77% for the AI. The reproducibility was dependent on SDB severity: AHI 15-29/h = 87%, AHI > or = 30/h = 92% and AI > or = 10/h = 83%. Classification was identical in 17 out of 19 patients with AI > or = 10/h. In patients with stable CHF a single night of cardiorespiratory monitoring leads to representative results on severity and type of SDB. This may enhance the applicability and dissemination of cardiorespiratory polygraphy in clinical practice.

Sleep-disordered breathing in the usual lifestyle setting as detected with home monitoring in a population of working men in Japan

STUDY OBJECTIVES

To examine (1) the prevalence of home-monitored sleep-disordered breathing (SDB) and obstructive sleep apnea syndrome in a Japanese working population and (2) whether home monitoring with a type 3 portable monitor and actigraphy can produce reliable data to analyze SDB in usual lifestyles.

METHODS

A cross-sectional survey using a self-administered questionnaire was conducted on a group of employees at a wholesale company in Osaka, Japan. Examinations by physicians and by sleep monitoring were also performed. Unattended home cardiorespiratory (type 3) sleep studies with actigraphy were conducted for 2 nights to diagnose SDB in 322 subjects. From the baseline questionnaires and sleep diaries, participants were assessed to follow their usual lifestyles during the study (e.g., time in bed, alcohol intake).

RESULTS

Of 466 Japanese male employees, 396 responded to the questionnaire survey (85.0%). Results from 322 male employees aged 23 to 59 (43.8 +/- 8.4 years) were analyzed. Respiratory disturbance index (RDI), calculated from the type 3 portable monitors and actigraphy, was highly reliable with an intraclass correlation of 0.98 for interscorer reliability and with an intraclass correlation of 0.95 for night-to-night reliability. Prevalence of mild (5 < or = RDI < 15), moderate (15 < or = RDI < 30) and severe (RDI < or = 30) SDB in this population were 37.4%, 15.7%, and 6.6%, respectively. The prevalence of obstructive sleep apnea syndrome (RDI > or = 5 and Epworth Sleepiness Scale score > 10) was 17.6%.

CONCLUSIONS

The prevalence of moderate to severe SDB (RDI > or = 15) was 22.3% in this Japanese male working population aged 23 to 59, measured in participant's usual life settings. Unattended home monitoring with type 3 portable monitors and actigraphy was highly reliable and may be suitable for analyzing SDB in the usual lifestyle setting.