ORCID Profile
0000-0003-4017-821X
Current Organisations
University of Queensland
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University of Eastern Finland
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Publisher: Elsevier BV
Date: 09-2020
Publisher: Springer Science and Business Media LLC
Date: 11-07-2019
Publisher: American Academy of Sleep Medicine (AASM)
Date: 15-08-2019
DOI: 10.5664/JCSM.7806
Publisher: Springer Science and Business Media LLC
Date: 23-09-2022
DOI: 10.1038/S41598-022-19892-0
Abstract: Sleep research often relies on large retrospective clinical datasets. However, as the data is usually stored in proprietary formats specific for each sleep software, the raw data cannot be easily accessed and analyzed with external tools. While the raw data can usually be exported to more common data formats, this is often a cumbersome and labor-intensive task as it is not required for clinical purposes. Additionally, the recordings often include sensitive patient information which must be removed before the data can be shared or analyzed externally. This anonymization can be difficult to perform manually without the correct tools or knowledge of the file types and how they internally store the data. The STAR sleep recording export software provides a simple tool that can be used to perform the sleep study exports automatically. This allows the user to easily export a batch of sleep studies with minimal effort. In addition, the software can also be used to automatically anonymize the exported sleep recordings allowing researchers to save time and personnel resources as these do not need to be allocated for exporting and anonymizing sleep studies. The software supports Noxturnal, RemLogic, Profusion PSG and Sleepware G3 and it is free and openly available for anyone to download and use.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2023
Publisher: Frontiers Media SA
Date: 28-04-2021
DOI: 10.3389/FNINS.2021.657126
Abstract: Obesity, older age, and male sex are recognized risk factors for sleep apnea. However, it is unclear whether the severity of hypoxic burden, an essential feature of sleep apnea, is associated with the risk of sleep apnea worsening. Thus, we investigated our hypothesis that the worsening of sleep apnea is expedited in in iduals with more severe desaturations. The blood oxygen saturation (SpO 2 ) signals of 805 Sleep Heart Health Study participants with mild sleep apnea [5 ≤ oxygen desaturation index (ODI) & 15] were analyzed at baseline and after a mean follow-up time of 5.2 years. Linear regression analysis, adjusted for relevant covariates, was utilized to study the association between baseline SpO 2 -derived parameters and change in sleep apnea severity, determined by a change in ODI. SpO 2 -derived parameters, consisting of ODI, desaturation severity (DesSev), desaturation duration (DesDur), average desaturation area (avg. DesArea), and average desaturation duration (avg. DesDur), were standardized to enable comparisons between the parameters. In the group consisting of both men and women, avg. DesDur (β = 1.594, p = 0.001), avg. DesArea (β = 1.316, p = 0.004), DesDur (β = 0.998, p = 0.028), and DesSev (β = 0.928, p = 0.040) were significantly associated with sleep apnea worsening, whereas ODI was not (β = −0.029, p = 0.950). In sex-stratified analysis, avg. DesDur (β = 1.987, p = 0.003), avg. DesArea (β = 1.502, p = 0.024), and DesDur (β = 1.374, p = 0.033) were significantly associated with sleep apnea worsening in men. Longer and deeper desaturations are more likely to expose a patient to the worsening of sleep apnea. This information could be useful in the planning of follow-up monitoring or lifestyle counseling in the early stage of the disease.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 22-01-2015
DOI: 10.1007/S11325-015-1118-X
Abstract: Recently, there has been a debate about the rules used to score hypopnea events. The purpose of this study was to examine the effect of different oxygen desaturation threshold (ODT) levels on the apnea-hypopnea index (AHI) and on a recently introduced parameter, adjusted AHI. Adjusted AHI incorporates the severity of in idual breathing cessation events. We also aimed to clarify the impact of the different ODT levels on the current classification of obstructive sleep apnea (OSA) severity. Ambulatory polygraphic recordings of 68 patients (19 F/49 M, median age 53.2 years, AHI ≥5) were analyzed retrospectively. Hypopneas were defined as ≥30% drop in airflow for ≥10 s associated with ≥2% oxygen desaturation (ODT2%), and after that, using stricter ODT criteria (ODT3%-ODT8%). Compared to ODT4%, the ODT3% resulted in 5.6 events/h higher median conventional AHI, but only 1.5 events/h higher median adjusted AHI. A significant rearrangement of patients between the clinical severity categories took place when using different ODTs. When assessing with ODT3% instead of ODT4%, the portion of the patients with moderate or severe OSA (AHI ≥15) raised from 29.4 to 73.5% using conventional AHI, but only marginally, i.e., from 73.5 to 77.9%, using the adjusted AHI. The conventional AHI was found to be susceptible even to minor changes in ODT level which may lead to substantial variability in AHI-based classification of disease severity. Since the adjusted AHI comprises information on severity of in idual breathing cessations, it reduces the variability related to ODT levels used in hypopnea scoring and can increase the accuracy of estimation of OSA severity.
Publisher: Wiley
Date: 10-08-2021
DOI: 10.1111/JSR.13441
Abstract: Intermittent hypoxaemia is a risk factor for numerous diseases. However, the reverse pathway remains unclear. Therefore, we investigated whether pre‐existing hypertension, diabetes or cardiovascular diseases are associated with the worsening of intermittent hypoxaemia. Among the included 2,535 Sleep Heart Health Study participants, hypertension ( n = 1,164), diabetes ( n = 170) and cardiovascular diseases ( n = 265) were frequently present at baseline. All participants had undergone two polysomnographic recordings approximately 5.2 years apart. Covariate‐adjusted linear regression analyses were utilized to investigate the difference in the severity of intermittent hypoxaemia at baseline between each comorbidity group and the group of participants free from all comorbidities ( n = 1,264). Similarly, we investigated whether the pre‐existing comorbidities are associated with the progression of intermittent hypoxaemia. Significantly higher oxygen desaturation index (β = 1.77 [95% confidence interval: 0.41–3.13], p = 0.011), desaturation severity (β = 0.07 [95% confidence interval: 0.00–0.14], p = 0.048) and desaturation duration (β = 1.50 [95% confidence interval: 0.31–2.69], p = 0.013) were observed in participants with pre‐existing cardiovascular diseases at baseline. Furthermore, the increase in oxygen desaturation index (β = 3.59 [95% confidence interval: 1.78–5.39], p 0.001), desaturation severity (β = 0.08 [95% confidence interval: 0.02–0.14], p = 0.015) and desaturation duration (β = 2.60 [95% confidence interval: 1.22–3.98], p 0.001) during the follow‐up were higher among participants with diabetes. Similarly, the increase in oxygen desaturation index (β = 2.73 [95% confidence interval: 1.15–4.32], p = 0.001) and desaturation duration (β = 1.85 [95% confidence interval: 0.62–3.08], p = 0.003) were higher among participants with cardiovascular diseases. These results suggest that patients with pre‐existing diabetes or cardiovascular diseases are at increased risk for an expedited worsening of intermittent hypoxaemia. As intermittent hypoxaemia is an essential feature of sleep apnea, these patients could benefit from the screening and follow‐up monitoring of sleep apnea.
Publisher: Oxford University Press (OUP)
Date: 13-09-2022
Abstract: Sleep stability can be studied by evaluating the cyclic alternating pattern (CAP) in electroencephalogram (EEG) signals. The present study presents a novel approach for assessing sleep stability, developing an index based on the CAP A-phase characteristics to display a sleep stability profile for a whole night’s sleep. Two ensemble classifiers were developed to automatically score the signals, one for “A-phase” and the other for “non-rapid eye movement” estimation. Both were based on three one-dimension convolutional neural networks. Six different inputs were produced from the EEG signal to feed the ensembles’ classifiers. A proposed heuristic-oriented search algorithm in idually tuned the classifiers’ structures. The outputs of the two ensembles were combined to estimate the A-phase index (API). The models can also assess the A-phase subtypes, their API, and the CAP cycles and rate. Four dataset variations were considered, examining healthy and sleep-disordered subjects. The A-phase average estimation’s accuracy, sensitivity, and specificity range was 82%–87%, 72%–80%, and 82%–88%, respectively. A similar performance was attained for the A-phase subtype’s assessments, with an accuracy range of 82%–88%. Furthermore, in the examined dataset’s variations, the API metric’s average error varied from 0.15 to 0.25 (with a median range of 0.11–0.24). These results were attained without manually removing wake or rapid eye movement periods, leading to a methodology suitable to produce a fully automatic CAP scoring algorithm. Metrics based on API can be understood as a new view for CAP analysis, where the goal is to produce and examine a sleep stability profile.
Publisher: Wiley
Date: 08-12-2022
DOI: 10.1111/JSR.13803
Abstract: Obstructive sleep apnea (OSA)‐related intermittent hypoxaemia is a potential risk factor for different OSA comorbidities, for ex le cardiovascular disease. However, conflicting results are found as to whether intermittent hypoxaemia is associated with impaired vigilance. Therefore, we aimed to investigate how desaturation characteristics differ between the non‐impaired vigilance and impaired vigilance patient groups formed based on psychomotor vigilance task (PVT) performance and compared with traditional OSA severity parameters. The study population comprised 863 patients with suspected OSA who underwent a PVT test before polysomnography. The conventional OSA parameters, for ex le, the apnea‐hypopnea index, oxygen desaturation index, and arousal index were computed. Furthermore, the median desaturation area, fall area, recovery area, and desaturation depth were computed with the pre‐event baseline reference and with reference to the 100% oxygen saturation level. Patients were grouped into best‐ and worst‐performing quartiles based on the number of lapses in PVT (Q1: PVT lapses and Q4: PVT lapses ). The association between parameters and impaired vigilance was evaluated by cumulative distribution functions (CDFs) and binomial logistic regression. Based on the CDFs, patients in Q4 had larger desaturation areas, recovery areas, and deeper desaturations when these were referenced to 100% saturation compared with Q1. The odds ratio (OR) of the median desaturation area (OR = 1.56), recovery area (OR = 1.71), and depth (OR = 1.65) were significantly elevated in Q4 in regression models. However, conventional OSA parameters were not significantly associated with impaired vigilance (ORs: 0.79–1.09). Considering desaturation parameters with a 100% SpO 2 reference in the diagnosis of OSA could provide additional information on the severity of OSA and related daytime vigilance impairment.
Publisher: IOP Publishing
Date: 28-11-2018
Abstract: Adherence to continuous positive airway pressure (CPAP) is often limited. The aim of the current work was to create a simulation tool to enable determination of the in idual CPAP therapy time required to normalize apnea-hypopnea index (AHI) (<5 events h Polygraphic studies of 1989 consecutive patients were analyzed. CPAP therapy was simulated in 5 min intervals starting from the beginning of the night and continuing until the end. In simulation, events inside the simulated CPAP therapy periods were considered to be prevented. The cutoff points where AHI reached a normal level of < 5 events h The median values of the required simulated CPAP usage times to normalize the AHI values were 3.3 h, 5.6 h and 6.5 h in the mild, moderate and severe OSA categories, respectively. However, there were great differences between in iduals in the CPAP usage times required to normalize AHI. An arbitrary threshold for CPAP adherence (e.g. 4 h) leaves many OSA patients with a significant residual AHI, which could explain why some clinical trials fail to show significant benefits. Thresholds for adherence should be adjusted based on the patient-specific distribution of obstruction events during the night.
Publisher: MDPI AG
Date: 17-05-2023
DOI: 10.3390/DIAGNOSTICS13101776
Abstract: Obstructive sleep apnea (OSA) severity assessment is based on manually scored respiratory events and their arbitrary definitions. Thus, we present an alternative method to objectively evaluate OSA severity independently of the manual scorings and scoring rules. A retrospective envelope analysis was conducted on 847 suspected OSA patients. Four parameters were calculated from the difference between the nasal pressure signal’s upper and lower envelopes: average (AV), median (MD), standard deviation (SD), and coefficient of variation (CoV). We computed the parameters from the entirety of the recorded signals to perform binary classifications of patients using three different apnea–hypopnea index (AHI) thresholds (5-15-30). Additionally, the calculations were undertaken in 30-second epochs to estimate the ability of the parameters to detect manually scored respiratory events. Classification performances were assessed with areas under the curves (AUCs). As a result, the SD (AUCs ≥ 0.86) and CoV (AUCs ≥ 0.82) were the best classifiers for all AHI thresholds. Furthermore, non-OSA and severe OSA patients were separated well with SD (AUC = 0.97) and CoV (AUC = 0.95). Respiratory events within the epochs were identified moderately with MD (AUC = 0.76) and CoV (AUC = 0.82). In conclusion, envelope analysis is a promising alternative method by which to assess OSA severity without relying on manual scoring or the scoring rules of respiratory events.
Publisher: Springer Science and Business Media LLC
Date: 13-12-2016
DOI: 10.1007/S11325-016-1430-0
Abstract: In obstructive sleep apnea (OSA), severity of in idual obstruction events is connected to increased mortality rate and it can be significantly different in patients with similar apnea-hypopnea index (AHI). However, possible gender-dependent variation in severity of obstruction events in different OSA categories is unknown. We investigated whether the severity of obstruction events differs between genders with similar AHI and if this difference varies between OSA categories. Polygraphic recordings of 2057 consecutive patients with suspected OSA were reanalyzed and those with AHI ≥5/h were included for further analysis (n Apneas were 16.9 and 19.6% longer (MWU p ≤ 0.015, GLM p ≤ 0.036) and desaturation areas were 15.4 and 23.7% larger (MWU p ≤ 0.024, GLM p ≤ 0.053) in males compared to females with moderate and severe OSA, respectively. In contrast, hypopneas were 9.1% shorter (MWU p = 0.001, GLM p ≤ 0.001) and desaturation areas were 6.0% smaller (MWU p = 0.114, GLM p = 0.025) in men with mild OSA. The apnea index was 433.3 and 313.1% higher (MWU p ≤ 0.001, GLM p ≤ 0.043) and the hypopnea index was 12.2 and 17.8% lower (MWU p ≤ 0.001, GLM p = 0.002, p = 0.083) in males with mild and moderate OSA, respectively. As severity of in idual obstruction events was significantly different in males and females, the overall severity of OSA may not be similar despite the similarity in AHI.
Publisher: Wiley
Date: 13-11-2019
DOI: 10.1002/LARY.28387
Abstract: Obstructive sleep apnea (OSA) patients with breathing abnormalities only or mainly in the supine posture are designated positional patients (PPs), whereas nonpositional patients (NPPs) have many breathing abnormalities in both lateral and supine postures. Positional therapy (PT), the avoidance of the supine posture during sleep, is the obvious treatment for PPs. The stability over time of being PP and leading factors that are involved in converting a PP to an NPP are addressed. We analyzed polysomnographic (PSG) recordings of 81 consecutive adult patients with OSA who were judged to be PPs at the first PSG evaluation, and their follow-up PSGs were obtained after an average period of 6.6 years. The follow-up PSGs indicated that 57 PPs (70.4%) remained PPs, whereas 24 (29.6 %) converted to NPPs. Among PPs and NPPs, body mass index (P ≤ 0.05), overall Apnea-Hypopnea Index (AHI, P ≤ 0.087), and lateral AHI (P ≤ 0.046) increased and minimum SpO After an average of 6.6 years, 70.4% of PPs remained PPs. Therefore, if adherence for PT is good, they could continue to benefit from this therapy. For those who turned to NPPs, PT will not be the optimal treatment anymore thus, these patients should be frequently monitored. Furthermore, an early treatment of PPs with PT would be highly beneficial to prevent worsening of their OSA. 2b Laryngoscope, 130:2263-2268, 2020.
Publisher: Springer Science and Business Media LLC
Date: 21-04-2015
DOI: 10.1007/S11325-015-1180-4
Abstract: Weight loss leads to improvement of obstructive sleep apnea (OSA), based on frequency of respiratory events (apnea-hypopnea index, AHI). However, AHI does not incorporate the severity of in idual obstruction events. The American Academy of Sleep Medicine suggests two alternative oxygen desaturation thresholds (ODT) for scoring of hypopneas. We hypothesize that lowering the ODT level increases the determined impact of weight loss on OSA severity. We investigate this during weight change with AHI and adjusted AHI. Adjusted AHI is a novel parameter incorporating both severity and number of the events. Ambulatory polygraphic data of 54 OSA patients (F 15/M 39, 51.7 ± 8.4 years), ided into weight loss (>5 %, n = 20), control (weight change 0-5 %, n = 26), and weight gain (>5 %, n = 8) groups, were evaluated at baseline and after 5-year follow-up. Effect of ODT (ODT2%-ODT6%) on AHI and adjusted AHI was investigated. The greatest changes in AHI (decrease in weight loss group and increase in weight gain group) were observed with ODT2%. Changes in AHI diminished with increasing ODT. In weight loss group, adjusted AHI showed a similar but non-significant trend. In contrast, the higher ODT was used in weight gain group, the greater increase in adjusted AHI resulted. Using adjusted AHI instead of AHI, led to a smaller number of patients (20 vs. 55 %, ODT3%) whose OSA severity category improved along weight loss. Weight loss significantly reduced AHI. This reduction was highly dependent on selected ODT. The change in adjusted AHI did not occur in the same extent. This was expected as the more severe events which tend to remain during the weight loss have greater importance in adjusted AHI, while the event severity is neglected in AHI.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: Springer Science and Business Media LLC
Date: 14-01-2020
DOI: 10.1007/S11325-019-02010-2
Abstract: Obstructive sleep apnea (OSA) is associated with increased risk for stroke, which is known to further impair respiratory functions. However, it is unknown whether the type and severity of respiratory events are linked to stroke or transient ischemic attack (TIA). Thus, we investigate whether the characteristics of in idual respiratory events differ between patients experiencing TIA or acute ischemic stroke and matched patients with clinically suspected sleep-disordered breathing. Polygraphic data of 77 in-patients with acute ischemic stroke ( n = 49) or TIA ( n = 28) were compared to age, gender, and BMI-matched patients with suspected sleep-disordered breathing and no cerebrovascular disease. Along with conventional diagnostic parameters (e.g., apnea-hypopnea index), durations and severities of in idual apneas, hypopneas and desaturations were compared between the groups separately for ischemic stroke and TIA patients. Stroke and TIA patients had significantly shorter apneas and hypopneas ( p 0.001) compared to matched reference patients. Furthermore, stroke patients had more central apnea events ( p = 0.007) and a trend for higher apnea/hypopnea number ratios ( p = 0.091). The prevalence of OSA (apnea-hypopnea index ≥ 5) was 90% in acute stroke patients and 79% in transient ischemic attack patients. Stroke patients had different characteristics of respiratory events, i.e., their polygraphic phenotype of OSA differs compared to matched reference patients. The observed differences in polygraphic features might indicate that stroke and TIA patients suffer from OSA phenotype recently associated with increased cardiovascular mortality. Therefore, optimal diagnostics and treatment require routine OSA screening in patients with acute cerebrovascular disease, even without previous suspicion of OSA.
Publisher: Oxford University Press (OUP)
Date: 07-05-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: Wiley
Date: 18-06-2020
DOI: 10.1111/JSR.13070
Publisher: Wiley
Date: 30-06-2022
DOI: 10.1111/JSR.13630
Abstract: Obstructive sleep apnea is linked to severe health consequences such as hypertension, daytime sleepiness, and cardiovascular disease. Nearly a billion people are estimated to have obstructive sleep apnea with a substantial economic burden. However, the current diagnostic parameter of obstructive sleep apnea, the apnea–hypopnea index, correlates poorly with related comorbidities and symptoms. Obstructive sleep apnea severity is measured by counting respiratory events, while other physiologically relevant consequences are ignored. Furthermore, as the clinical methods for analysing polysomnographic signals are outdated, laborious, and expensive, most patients with obstructive sleep apnea remain undiagnosed. Therefore, more personalised diagnostic approaches are urgently needed. The Sleep Revolution, funded by the European Union's Horizon 2020 Research and Innovation Programme, aims to tackle these shortcomings by developing machine learning tools to better estimate obstructive sleep apnea severity and phenotypes. This allows for improved personalised treatment options, including increased patient participation. Also, implementing these tools will alleviate the costs and increase the availability of sleep studies by decreasing manual scoring labour. Finally, the project aims to design a digital platform that functions as a bridge between researchers, patients, and clinicians, with an electronic sleep diary, objective cognitive tests, and questionnaires in a mobile application. These ambitious goals will be achieved through extensive collaboration between 39 centres, including expertise from sleep medicine, computer science, and industry and by utilising tens of thousands of retrospectively and prospectively collected sleep recordings. With the commitment of the European Sleep Research Society and Assembly of National Sleep Societies, the Sleep Revolution has the unique possibility to create new standardised guidelines for sleep medicine.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Oxford University Press (OUP)
Date: 09-2021
Publisher: Wiley
Date: 29-07-2021
DOI: 10.1111/JSR.13431
Abstract: To aim is investigate whether demographic, polysomnographic or sleep behaviour data differ between non‐sleepy, sleepy and very sleepy patients with mild obstructive sleep apnea. The study population consisted of 439 consecutive adult patients diagnosed with mild obstructive sleep apnea (5 ≤ apnea–hypopnea index 15) after a complete polysomnographic evaluation. The patients were ided into three groups based on subjective sleepiness: very sleepy (Epworth Sleepiness Scale ≥ 16, n = 59) sleepy (10 Epworth Sleepiness Scale 16, n = 102) and non‐sleepy (Epworth Sleepiness Scale ≤ 10, n = 278). Demographic, polysomnographic and sleep behaviour data were compared between the groups. There were no statistically significant differences in breathing abnormality indices and most of the demographic features between the groups. The number of arousals was significantly higher in the very sleepy group compared with the non‐sleepy group (140.8 ± 105.2 versus 107.6 ± 72.2). Very sleepy patients reported feeling sleepy during the daytime more often (42.4% versus 31.7%) and sleeping significantly less during the week compared with non‐sleepy patients. Also, a significantly higher proportion of sleepy (47.1%) and very sleepy patients (44.1%) reported taking naps during weekends compared with non‐sleepy patients (35.6%). In a regression analysis, also total sleep time ( β = 0.045), sleep efficiency ( β = −0.160), apnea index ( β = −0.397), apnea–hypopnea index in supine position ( β = 0.044), periodic limb movement index ( β = 0.196) and periodic limb movement‐related arousal index ( β = −0.210) affected subjective daytime sleepiness. The results suggest that excessive daytime sleepiness in patients with mild obstructive sleep apnea appears to be related to inadequate sleeping habits (i.e. insufficient sleep during working days) and decreased sleep quality rather than differences in breathing abnormalities.
Publisher: Hindawi Limited
Date: 2016
DOI: 10.1155/2016/9645347
Abstract: Positional obstructive sleep apnea (OSA) is common among OSA patients. In severe OSA, the obstruction events are longer in supine compared to nonsupine positions. Corresponding scientific information on mild and moderate OSA is lacking. We studied whether in idual obstruction and desaturation event severity is increased in supine position in all OSA severity categories and whether the severity of in idual events is linked to OSA severity categories. Polygraphic recordings of 2026 patients were retrospectively analyzed. The in idual apnea, and hypopnea durations and desaturation event depth, duration, and area of 526 included patients were compared between supine and nonsupine positions in different OSA severity categories. Apnea events were 6.3%, 12.5%, and 11.1% longer ( p 0.001 ) in supine compared to nonsupine position in mild, moderate, and severe OSA categories, respectively. In moderate and severe OSA categories desaturation areas were 5.7% and 25.5% larger ( p 0.001 ) in supine position. In both positions the in idual event severity was elevated along increasing OSA severity category ( p 0.05 ). Supine position elevates apnea duration in all and desaturation area in moderate and severe OSA severity categories. This might be more hazardous for supine OSA patients and therefore, estimation of clinical severity of OSA should incorporate also information about in idual event characteristics besides AHI.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: Wiley
Date: 13-06-2023
DOI: 10.1111/JSR.13956
Abstract: Determining sleep stages accurately is an important part of the diagnostic process for numerous sleep disorders. However, as the sleep stage scoring is done manually following visual scoring rules there can be considerable variation in the sleep staging between different scorers. Thus, this study aimed to comprehensively evaluate the inter‐rater agreement in sleep staging. A total of 50 polysomnography recordings were manually scored by 10 independent scorers from seven different sleep centres. We used the 10 scorings to calculate a majority score by taking the sleep stage that was the most scored stage for each epoch. The overall agreement for sleep staging was κ = 0.71 and the mean agreement with the majority score was 0.86. The scorers were in perfect agreement in 48% of all scored epochs. The agreement was highest in rapid eye movement sleep ( κ = 0.86) and lowest in N1 sleep ( κ = 0.41). The agreement with the majority scoring varied between the scorers from 81% to 91%, with large variations between the scorers in sleep stage‐specific agreements. Scorers from the same sleep centres had the highest pairwise agreements at κ = 0.79, κ = 0.85, and κ = 0.78, while the lowest pairwise agreement between the scorers was κ = 0.58. We also found a moderate negative correlation between sleep staging agreement and the apnea–hypopnea index, as well as the rate of sleep stage transitions. In conclusion, although the overall agreement was high, several areas of low agreement were also found, mainly between non‐rapid eye movement stages.
Publisher: Springer Science and Business Media LLC
Date: 17-04-2015
DOI: 10.1007/S11517-015-1290-Y
Abstract: Severity of obstructive sleep apnea (OSA) is estimated based on respiratory events per hour [i.e., apnea-hypopnea index (AHI)]. The aim of this study was to investigate effects of weight change on the severity of respiratory events. Respiratory event severity, including duration and morphology, was estimated by determining parameters quantifying obstruction and desaturation event lengths and areas, respectively. Respiratory events of 54 OSA patients treated with dietary intervention were evaluated at baseline and after 5-year follow-up in subgroups with different levels of weight change. AHI, oxygen desaturation index (ODI) and obstruction event severities decreased during weight loss. In lower level weight loss, the decrease was milder in obstruction severity than in AHI and ODI, indicating that the decrease in the number of events is more focused on less severe events. In weight gain groups, parameters incorporating obstruction event severity, AHI and ODI increased, although increase was greater in parameters incorporating obstruction event severity. The number and severity of respiratory events were modulated differently by the level of weight change. AHI misses this change in the severity of respiratory events. Therefore, parameters incorporating information on the respiratory event severities may bring additional information on the health effects obtained with dietary treatment of OSA.
Publisher: The Korean Society of Medical Informatics
Date: 2018
Publisher: Daedalus Enterprises
Date: 21-12-2018
Abstract: Obesity is one of the most prominent risk factors for obstructive sleep apnea (OSA). Weight loss decreases the number of shorter respiratory events (<40 s), whereas the number of longer events remains almost unchanged. However, it is unknown how body mass index (BMI) affects in idual obstruction event severity within OSA severity categories when age, sex, smoking, daytime sleepiness, snoring, hypertension, heart failure, and sleeping posture are considered. Therefore, we investigated whether in idual obstruction event severity varies with BMI within the OSA severity categories when considering the most important confounding factors. Polygraphic recordings of 723 subjects without CPAP treatment and with an apnea-hypopnea index (AHI) of ≥5 events/hour were reanalyzed retrospectively. The effect of BMI on the severities of OSA and in idual obstruction events was evaluated in general, within OSA severity categories, and between different BMI groups (ie, BMI < 25 25 ≤ BMI < 30 30 ≤ BMI < 35 35 ≤ BMI < 40 and BMI ≥ 40 kg/m AHI increased in mild and severe (β ≥ 0.10, Because BMI is related to the duration of in idual obstruction events, its effect on OSA severity is more complex than its effect on AHI would implicate. Therefore, overall severity of OSA may not be the same for non-obese patient and obese patient who have similar AHI. Thus, these patient-specific characteristics of in idual breathing cessations should be considered when estimating the severity of disease and risk of related adverse health effects.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Elsevier BV
Date: 11-2022
DOI: 10.1016/J.CMPB.2022.107120
Abstract: Many sleep recording software used in clinical settings have some tools to automatically analyze the blood oxygen saturation (SpO ABOSA was programmed with MATLAB. ABOSA automatically detects desaturation and recovery events from the SpO The agreements between ABOSA and manual scorings were great in both Kuopio (MCC = 0.801) and Loewenstein (MCC = 0.898) datasets. However, ABOSA slightly overestimated the desaturation parameter values. The median differences in ODIs were 0.8 (Kuopio) and 0.0 (Loewenstein) events/h. Similarly, the median differences in DesSevs were 0.02 (Kuopio) and 0.01 (Loewenstein) percentage points. In a second-by-second analysis, ABOSA performed very similarly to Noxturnal and Profusion software in both Kuopio (MCC ABOSA is an accurate and freely available software that calculates both traditional clinical parameters and novel parameters, provides a detailed characterization of desaturation and recovery events, and enables batch analysis of large datasets. These are features that no other software currently provides making ABOSA uniquely suitable for scientific research use.
Publisher: Wiley
Date: 15-03-2022
DOI: 10.1111/JSR.13581
Abstract: 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 ided 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 SpO 2 %), 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.
Publisher: Oxford University Press (OUP)
Date: 05-06-2021
Abstract: To assess the relationship between obstructive sleep apnea (OSA) severity and sleep fragmentation, accurate differentiation between sleep and wakefulness is needed. Sleep staging is usually performed manually using electroencephalography (EEG). This is time-consuming due to complexity of EEG setup and the amount of work in manual scoring. In this study, we aimed to develop an automated deep learning-based solution to assess OSA-related sleep fragmentation based on photoplethysmography (PPG) signal. A combination of convolutional and recurrent neural networks was used for PPG-based sleep staging. The models were trained using two large clinical datasets from Israel (n = 2149) and Australia (n = 877) and tested separately on three-class (wake/NREM/REM), four-class (wake/N1 + N2/N3/REM), and five-class (wake/N1/N2/N3/REM) classification. The relationship between OSA severity categories and sleep fragmentation was assessed using survival analysis of mean continuous sleep. Overlapping PPG epochs were applied to artificially obtain denser hypnograms for better identification of fragmented sleep. Automatic PPG-based sleep staging achieved an accuracy of 83.3% on three-class, 74.1% on four-class, and 68.7% on five-class models. The hazard ratios for decreased mean continuous sleep compared to the non-OSA group obtained with Cox proportional hazards models with 5-s epoch-to-epoch intervals were 1.70, 3.30, and 8.11 for mild, moderate, and severe OSA, respectively. With EEG-based hypnograms scored manually with conventional 30-s epoch-to-epoch intervals, the corresponding hazard ratios were 1.18, 1.78, and 2.90. PPG-based automatic sleep staging can be used to differentiate between OSA severity categories based on sleep continuity. The differences between the OSA severity categories become more apparent when a shorter epoch-to-epoch interval is used.
Publisher: Oxford University Press (OUP)
Date: 21-05-2020
Abstract: Accurate identification of sleep stages is essential in the diagnosis of sleep disorders (e.g. obstructive sleep apnea [OSA]) but relies on labor-intensive electroencephalogram (EEG)-based manual scoring. Furthermore, long-term assessment of sleep relies on actigraphy differentiating only between wake and sleep periods without identifying specific sleep stages and having low reliability in identifying wake periods after sleep onset. To address these issues, we aimed to develop an automatic method for identifying the sleep stages from the photoplethysmogram (PPG) signal obtained with a simple finger pulse oximeter. PPG signals from the diagnostic polysomnographies of susptected OSA patients (n = 894) were utilized to develop a combined convolutional and recurrent neural network. The deep learning model was trained in idually for three-stage (wake/NREM/REM), four-stage (wake/N1+N2/N3/REM), and five-stage (wake/N1/N2/N3/REM) classification of sleep. The three-stage model achieved an epoch-by-epoch accuracy of 80.1% with Cohen’s κ of 0.65. The four- and five-stage models achieved 68.5% (κ = 0.54), and 64.1% (κ = 0.51) accuracies, respectively. With the five-stage model, the total sleep time was underestimated with a mean bias error (SD) of of 7.5 (55.2) minutes. The PPG-based deep learning model enabled accurate estimation of sleep time and differentiation between sleep stages with a moderate agreement to manual EEG-based scoring. As PPG is already included in ambulatory polygraphic recordings, applying the PPG-based sleep staging could improve their diagnostic value by enabling simple, low-cost, and reliable monitoring of sleep and help assess otherwise overlooked conditions such as REM-related OSA.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 07-2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2023
Publisher: IOP Publishing
Date: 26-07-2017
Abstract: Severity estimation of obstructive sleep apnea (OSA) is currently based on the apnea-hypopnea index (AHI), which ignores in idual breathing cessation event characteristics. Gender differences in the relationship between the breathing cessation event duration and the related desaturation event severity could mean that the severity of OSA is different in males and females despite a similar AHI. The aim of this work was to evaluate gender differences in the severity of peripheral oxygen desaturation events following obstructive apneas or hypopneas. Type I polysomnographic recordings of 220 males and 175 females were analyzed. The obstructive apnea and hypopnea events were ided into eight different durational categories from 10 s to 45 s with 5 s interval and >45 s. The desaturation event severities following obstructive apneas or hypopneas were compared between genders within these durational categories. Desaturations following obstructive apneas with a duration of 30-45 s were substantially more severe (p < 0.05) in females compared to males. In contrast, areas of desaturations following hypopneas (with related hypopnea event durations ⩽30 s) were smaller (p 30 s) could be more detrimental compared to those of males. As severe health consequences are related to the desaturation severity these aspects should be considered when estimating the severity of OSA.
Publisher: European Respiratory Society (ERS)
Date: 06-02-2020
DOI: 10.1183/13993003.01849-2019
Abstract: Current diagnostic parameters estimating obstructive sleep apnoea (OSA) severity have a poor connection to the psychomotor vigilance of OSA patients. Thus, we aimed to investigate how the severity of apnoeas, hypopnoeas and intermittent hypoxaemia is associated with impaired vigilance. We retrospectively examined type I polysomnography data and corresponding psychomotor vigilance tasks (PVTs) of 743 consecutive OSA patients (apnoea–hypopnoea index (AHI) ≥5 events·h −1 ). Conventional diagnostic parameters ( e.g. AHI and oxygen desaturation index (ODI)) and novel parameters ( e.g. desaturation severity and obstruction severity) incorporating duration of apnoeas and hypopnoeas as well as depth and duration of desaturations were assessed. Patients were grouped into quartiles based on PVT outcome variables. The odds of belonging to the worst-performing quartile were assessed. Analyses were performed for all PVT outcome variables using binomial logistic regression. A relative 10% increase in median depth of desaturations elevated the odds (OR range 1.20–1.37, p .05) of prolonged mean and median reaction times as well as increased lapse count. Similarly, an increase in desaturation severity (OR range 1.26–1.52, p .05) associated with prolonged median reaction time. Female sex (OR range 2.21–6.02, p .01), Epworth Sleepiness Scale score (OR range 1.05–1.07, p .01) and older age (OR range 1.01–1.05, p .05) were significant risk factors in all analyses. In contrast, increases in conventional AHI, ODI and arousal index were not associated with deteriorated PVT performance. These results show that our novel parameters describing the severity of intermittent hypoxaemia are significantly associated with increased risk of impaired PVT performance, whereas conventional OSA severity and sleep fragmentation metrics are not. These results underline the importance of developing the assessment of OSA severity beyond the AHI.
Publisher: IOP Publishing
Date: 14-08-2013
DOI: 10.1088/0967-3334/34/9/1013
Abstract: Apnea-hypopnea-index (AHI), disregarding the respiratory event morphology, is currently used in estimation of severity of obstructive sleep apnea (OSA). The purpose of the current study was to evaluate the potential of novel parameters in estimation of changes in severity of OSA during weight loss. Polygraphic data of 67 patients, 37 in the control (no weight loss) and 30 in the weight loss (>5%) groups was evaluated at baseline and after two year follow-up. Changes in the values of novel parameters, incorporating detailed information of respiratory event characteristics, were evaluated and compared with changes in AHI. The median AHI in the weight loss group decreased significantly during the follow-up. The number of shorter respiratory events decreased in the weight loss group, while the longer ones remained, increasing the median durations of the respiratory events by 20-62%. For this reason the decrease of the values of the novel parameters were smaller compared to AHI in the weight loss group. This suggests that the severity of OSA might not fall as linearly during weight loss as AHI suggests. Moreover, the novel parameters containing more detailed information on the morphology characteristics may provide valuable supplementary information for the assessment of the severity of OSA.
Publisher: Wiley
Date: 03-04-2019
DOI: 10.1111/JSR.12855
Abstract: The severity of obstructive sleep apnea is clinically assessed mainly using the apnea-hypopnea index. Based on the apnea-hypopnea index, patients are classified into four severity groups: non-obstructive sleep apnea (apnea-hypopnea index < 5) mild (5 ≤ apnea-hypopnea index < 15) moderate (15 ≤ apnea-hypopnea index < 30) and severe obstructive sleep apnea (apnea-hypopnea index ≥ 30). However, these thresholds lack solid clinical and scientific evidence. We hypothesize that the current apnea-hypopnea index thresholds are not optimal despite their global use, and aim to assess this clinical shortcoming by optimizing the thresholds with respect to the risk of all-cause mortality. We analysed ambulatory polygraphic recordings of 1,783 patients with suspected obstructive sleep apnea (mean follow-up 18.3 years). We simulated 79,079 different threshold combinations in 100 randomized subgroups of the population and studied the relative risk of all-cause mortality corresponding to each combination and randomization. The optimal thresholds were chosen according to three criteria: (a) the hazard ratios increase linearly between severity groups towards more severe obstructive sleep apnea (b) each group includes at least 15% of the study population (c) group sizes decrease with increasing obstructive sleep apnea severity. The risk of all-cause mortality varied greatly across simulations the threshold defining non-obstructive sleep apnea group having the largest effect on the hazard ratios. The apnea-hypopnea index threshold combination of 3-9-24 was optimal in most of the subgroups. In conclusion, the assessment of obstructive sleep apnea severity based on the current apnea-hypopnea index thresholds is not optimal. Our novel approach provides methods for optimizing apnea-hypopnea index-based severity classification, and the revised thresholds better differentiate patients into severity groups, ensuring that an increase in the severity corresponds to an increase in the risk of all-cause mortality.
Publisher: Wiley
Date: 13-07-2023
DOI: 10.1111/JSR.13988
Abstract: Oxygen saturation (SpO 2 )‐based parameters are more strongly linked to impaired daytime vigilance than the conventional diagnostic metrics in patients with obstructive sleep apnea (OSA). However, whether the association between SpO 2 ‐based parameters and impaired daytime vigilance is modulated by sex, remains unknown. Hence, we investigated the interplay between sex and detailed SpO 2 ‐based metrics and their association with impaired vigilance in patients with OSA. The study population consisted of 855 (473 males, 382 females) patients with suspected OSA who underwent overnight polysomnography and psychomotor vigilance task (PVT). The population was grouped by sex and ided into quartiles (Q1–Q4) based on median reaction times (RTs) in the PVT. In addition to conventional diagnostic metrics, desaturation severity (DesSev), fall severity (FallSev), and recovery severity (RecovSev) were compared between the sexes and between the best (Q1) and worst (Q4) performing quartiles by using cumulative distribution functions (CDFs). Additionally, sex‐specific covariate‐adjusted linear regression models were used to investigate the connection between the parameters and RTs. The CDFs showed significantly higher hypoxic load in Q4 in males compared to females. In addition, the DesSev ( β = 8.05, p 0.01), FallSev ( β = 6.48, p = 0.02), RecovSev ( β = 9.13, p 0.01), and Oxygen Desaturation Index ( β = 12.29, p 0.01) were associated with increased RTs only in males. Conversely, the Arousal Index ( β = 10.75–11.04, p 0.01) was associated with impaired vigilance in females. The severity of intermittent hypoxaemia was strongly associated with longer RTs in males whereas the Arousal Index had the strongest association in females. Thus, the impact of hypoxic load on impaired vigilance seems to be stronger in males than females.
Publisher: IOP Publishing
Date: 19-09-2014
DOI: 10.1088/0967-3334/35/10/2037
Abstract: Weight loss is an effective treatment for obstructive sleep apnea (OSA). The mechanisms of how weight loss affects nocturnal breathing are not fully understood. The severity of OSA is currently estimated by the number of respiratory events per hour of sleep (i.e. apnea-hypopnea-index, AHI). AHI neglects duration and morphology of in idual respiratory events, which describe the severity of in idual events. In the current paper, we investigate the novel Adjusted-AHI parameter (incorporating in idual event severity) and AHI after weight loss in relation to sleeping position. It was hypothesised that there are positional differences in in idual event severity changes during weight loss. Altogether, 32 successful (> 5% of weight) and 34 unsuccessful weight loss patients at baseline and after 1 year follow-up were analysed. The results revealed that in idual respiratory event severity was reduced differently in supine and non-supine positions during weight loss. During weight loss, AHI was reduced by 54% (p = 0.004) and 74% (p < 0.001), while Adjusted-AHI was reduced by 14% (p = 0.454) and 48% (p = 0.003) in supine and non-supine positions, respectively. In conclusion, the severity of in idual respiratory events decreased more in the non-supine position. The novel Adjusted-AHI parameter takes these changes into account and might therefore contribute additional information to the planning of treatment of OSA patients.
Publisher: Springer Science and Business Media LLC
Date: 13-03-2020
DOI: 10.1038/S41598-020-62003-0
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2022
Publisher: European Respiratory Society (ERS)
Date: 07-2023
Publisher: IOP Publishing
Date: 06-11-2018
Abstract: In obstructive sleep apnea (OSA), breathing cessations are often followed by arousals, leading to sleep fragmentation and thus impaired sleep quality. Arousals and fragmented sleep are also related to detrimental cardiovascular events. The key index for OSA diagnosis (i.e. the apnea-hypopnea index) attributes equal diagnostic value to apneas and hypopneas, despite the fact that the associated arousals and desaturations may be very different. Thus, considering the severity of the consequences of apneas and hypopneas could enhance the estimation of OSA severity. In this study, we investigate whether the probability and duration of apnea- and hypopnea-related arousals differ and whether the differences in desaturation severity following apneas and hypopneas are dependent on sleep stage. Polysomnographic recordings of 348 consecutive OSA patients were included for analysis. The severity of arousals and desaturations associated with hypopneas within different sleep stages was compared to that of arousals and desaturations associated with apneas. In addition, the probability of arousals related to apneas and hypopneas was evaluated within OSA severity categories. Apneas caused arousals less frequently than hypopneas in N1, N2, and N3 sleep in all OSA severity categories. However, the arousals caused by apneas were longer (p < 0.001) and the desaturations related to apneas were more severe (p < 0.001) than those related to hypopneas in N1, N2, and rapid eye movement sleep even after adjustment for respiratory event durations. Desaturations and arousals related to apneas are more severe than those related to hypopneas. Therefore, apneas followed by arousal or desaturation should have a different diagnostic value than hypopneas when assessing OSA severity and related risk for cardiovascular consequences.
Publisher: European Respiratory Society (ERS)
Date: 24-09-2020
DOI: 10.1183/23120541.00277-2020
Abstract: Besides hypoxaemia severity, heart rate variability has been linked to cognitive decline in obstructive sleep apnoea (OSA) patients. Thus, our aim was to examine whether the frequency domain features of a nocturnal photoplethysmogram (PPG) can be linked to poor performance in the psychomotor vigilance task (PVT). PPG signals from 567 suspected OSA patients, extracted from Type 1 diagnostic polysomnography, and corresponding results of PVT were retrospectively examined. The frequency content of complete PPGs was determined, and analyses were conducted separately for men (n=327) and women (n=240). Patients were grouped into PVT performance quartiles based on the number of lapses (reaction times ≥500 ms) and within-test variation in reaction times. The best-performing (Q1) and worst-performing (Q4) quartiles were compared due the lack of clinical thresholds in PVT. We found that the increase in arterial pulsation frequency (APF) in both men and women was associated with a higher number of lapses. Higher APF was also associated with higher within-test variation in men, but not in women. Median APF (β=0.27, p=0.01), time spent under 90% saturation (β=0.05, p .01), female sex (β=1.29, p .01), older age (β=0.03, p .01) and subjective sleepiness (β=0.07, p .01) were significant predictors of belonging to Q4 based on lapses. Only female sex (β=0.75, p .01) and depression (β=0.91, p .02) were significant predictors of belonging to Q4 based on the within-test variation. In conclusion, increased APF in PPG provides a possible polysomnography indicator for deteriorated vigilance especially in male OSA patients. This finding highlights the connection between cardiorespiratory regulation, vigilance and OSA. However, our results indicate substantial sex-dependent differences that warrant further prospective studies.
Publisher: Elsevier BV
Date: 05-2021
Publisher: Informa UK Limited
Date: 15-03-2016
DOI: 10.3109/03091902.2016.1148791
Abstract: Obstructive sleep apnea (OSA) is diagnosed based on obstruction event incidence, albeit in idual obstruction event severity is connected to increased mortality rate. Adjusted-AHI parameter, incorporating number and severity of obstruction events, has shown good potential, but is calculated using custom-made MATLAB(®) functions. To allow its clinical use, this study introduces the RemLogic™ plug-in. It is tested comparing adjusted-AHI values calculated with the plug-in and MATLAB(®) with a hundred patients. Furthermore, retrospective follow-up (mean ± SD = 194.1 ± 54.0 months) of 1128 working-age men was conducted to evaluate potential of adjusted-AHI to enhance diagnostic of OSA. Adjusted-AHI values were strongly correlated (r = 1.000, p < 0.001) and their average difference (mean ± SD) was minimal (0.08 ± 0.19%). Using adjusted-AHI to define OSA severity resulted in a higher hazard ratio of mortality in the severe OSA group and, for the first time, adjusted-AHI was found to explain independently the overall mortality and non-fatal cardiovascular events. Importantly, the present plug-in enables clinical use of adjusted-AHI, enhancing assessment of OSA severity.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.SLEEP.2017.06.004
Abstract: Age is a risk factor of obstructive sleep apnea (OSA). It has been shown that OSA progresses over time, although conflicting results have been reported. However, the effect of age on the severity of OSA and in idual obstruction events has not been investigated within different OSA severity categories by taking the most prominent confounding factors (i.e., body mass index, gender, smoking, daytime sleepiness, snoring, hypertension, heart failure, and proportion of supine sleep) into account. Polygraphic data of 1090 patients with apnea-hypopnea index (AHI) ≥5 were retrospectively reanalyzed. The effect of age on the severity of OSA and obstruction events was investigated in general, within different OSA severity categories, and in different age groups (age <40, 40≤ age <50, 50≤ age <60, and age ≥60 years). In the whole population, AHI and durations of apneas, hypopneas, and desaturations increased with increasing age (B ≥ 0.108, p ≤ 0.010). In more detailed analysis, AHI increased with age only in the moderate OSA category (B = 0.075, p = 0.022), although durations of apneas increased in mild and severe OSA categories (B ≥ 0.076, p ≤ 0.038). Furthermore, durations of hypopneas increased with age in mild and moderate OSA categories (B ≥ 0.105, p ≤ 0.038), and durations of desaturations (B ≥ 0.120, p ≤ 0.013) in all OSA severity categories. AHI was not statistically significantly different between the age groups, although durations of obstruction events tended to increase towards older age groups. As obstruction event severity was more strongly dependent on the age than it was dependent on AHI, considering the severity of obstruction events could be beneficial while estimating the long-term effects of the treatments and prognosticating the disease progression.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2019
Publisher: European Respiratory Society (ERS)
Date: 28-07-2022
DOI: 10.1183/23120541.00121-2022
Abstract: Obstructive sleep apnoea (OSA) causes, among other things, intermittent blood oxygen desaturations, increasing the sympathetic tone. Yet the effect of desaturations on heart rate variability (HRV), a simple and noninvasive method for assessing sympathovagal balance, has not been comprehensively studied. We aimed to study whether desaturation severity affects the immediate HRV. We retrospectively analysed the electrocardiography signals in 5-min segments (n=39 132) recorded during clinical polysomnographies of 642 patients with suspected OSA. HRV parameters were calculated for each segment. The segments were pooled into severity groups based on the desaturation severity ( i.e. the integrated area under the blood oxygen saturation curve) and the respiratory event rate within the segment. Covariate-adjusted regression analyses were performed to investigate possible confounding effects. With increasing respiratory event rate, the normalised high-frequency band power (HF NU ) decreased from 0.517 to 0.364 (p .01), the normalised low-frequency band power (LF NU ) increased from 0.483 to 0.636 (p .01) and the mean RR interval decreased from 915 to 869 ms (p .01). Similarly, with increasing desaturation severity, the HF NU decreased from 0.499 to 0.364 (p .01), the LF NU increased from 0.501 to 0.636 (p .01) and the mean RR interval decreased from 952 to 854 ms (p .01). Desaturation severity-related findings were confirmed by considering the confounding factors in the regression analyses. The short-term HRV response differs based on the desaturation severity and the respiratory event rate in patients with suspected OSA. Therefore, a more detailed analysis of HRV and desaturation characteristics could enhance OSA severity estimation.
Publisher: Springer Science and Business Media LLC
Date: 20-07-2019
DOI: 10.1007/S11325-019-01897-1
Abstract: We assessed the prevalence of positional patients (PPs) and the main predictors of positional dependency in severe obstructive sleep apnea (OSA). A simulated effect of positional therapy (PT) vs. continuous positive airway pressure (CPAP) was also assessed. Polysomnographic recordings of 292 consecutive patients with severe OSA (Apnea-Hypopnea Index (AHI) ≥ 30) who slept > 4 h and had ≥ 30 min sleep in both supine and lateral positions were assessed. PPs were defined to have a supine AHI/lateral AHI ratio ≥ two and non-positional patients (NPPs) a supine AHI/lateral AHI ratio < two. A total of 35.3% of the severe OSA patients were PPs. They were less obese and had less severe OSA (p < 0.001) compared with NPPs. The percentage of total apnea-hypopnea time from total sleep time (AHT%) was the most significant predictor for positional dependency. By sleeping in the lateral posture (i.e. after simulated PT), 78 (75.7%) PPs obtained significant improvement of their OSA severity and 9 (8.7%) of them became "non-OSA". Moreover, if CPAP was used only for 50% of total sleep time, 53 patients (18.2%) gained more benefit from avoiding the supine posture than from CPAP therapy. More than a third of the studied severe OSA patients were PPs. These patients could achieve a significant decrease in the number and severity of apneas and hypopneas by adopting the lateral posture, suggesting that PT may be a valuable therapy for a significant portion of these severe OSA patients who for whatever reason are not being treated by CPAP. ClinicalTrials.gov Identifier: NCT03232658.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2021
Publisher: Elsevier BV
Date: 03-2021
Publisher: Oxford University Press (OUP)
Date: 27-05-2020
Abstract: A common symptom of obstructive sleep apnea (OSA) is excessive daytime sleepiness (EDS). The gold standard test for EDS is the multiple sleep latency test (MSLT). However, due to its high cost, MSLT is not routinely conducted for OSA patients and EDS is instead evaluated using sleep questionnaires. This is problematic however, since sleep questionnaires are subjective and correlate poorly with the MSLT. Therefore, new objective tools are needed for reliable evaluation of EDS. The aim of this study was to test our hypothesis that EDS can be estimated with neural network analysis of previous night polysomnographic signals. We trained a convolutional neural network (CNN) classifier using electroencephalography, electrooculography, and chin electromyography signals from 2,014 patients with suspected OSA. The CNN was trained to classify the patients into four sleepiness categories based on their mean sleep latency (MSL) severe (MSL & 5min), moderate (5 ≤ MSL & 10), mild (10 ≤ MSL & 15), and normal (MSL ≥ 15). The CNN classified patients to the four sleepiness categories with an overall accuracy of 60.6% and Cohen’s kappa value of 0.464. In two-group classification scheme with sleepy (MSL & 10 min) and non-sleepy (MSL ≥ 10) patients, the CNN achieved an accuracy of 77.2%, with sensitivity of 76.5%, and specificity of 77.9%. Our results show that previous night’s polysomnographic signals can be used for objective estimation of EDS with at least moderate accuracy. Since the diagnosis of OSA is currently confirmed by polysomnography, the classifier could be used simultaneously to get an objective estimate of the daytime sleepiness with minimal extra workload.
Publisher: Springer Science and Business Media LLC
Date: 13-09-2019
DOI: 10.1038/S41598-019-49330-7
Abstract: The severity of obstructive sleep apnea (OSA) is classified using apnea-hypopnea index (AHI). Accurate determination of AHI currently requires manual analysis and complicated registration setup making it expensive and labor intensive. Partially for these reasons, OSA is a heavily underdiagnosed disease as only 7% of women and 18% of men suffering from OSA have diagnosis. To resolve these issues, we introduce an artificial neural network (ANN) that estimates AHI and oxygen desaturation index (ODI) using only the blood oxygen saturation signal (SpO2), recorded during ambulatory polygraphy, as an input. Therefore, hypopneas associated only with an arousal were not considered in this study. SpO2 signals from 1692 patients were used for training and 99 for validation. Two test sets were used consisting of 198 and 1959 patients. In the primary test set, the median absolute errors of ANN estimated AHI and ODI were 0.78 events/hour and 0.68 events/hour respectively. Based on the ANN estimated AHI and ODI, 90.9% and 94.4% of the test patients were classified into the correct OSA severity category. In conclusion, AHI and ODI can be reliably determined using neural network analysis of SpO2 signal. The developed method may enable a more affordable screening of OSA.
Publisher: Wiley
Date: 03-07-2023
DOI: 10.1111/JSR.13977
Abstract: Sleep recordings are increasingly being conducted in patients’ homes where patients apply the sensors themselves according to instructions. However, certain sensor types such as cup electrodes used in conventional polysomnography are unfeasible for self‐application. To overcome this, self‐applied forehead montages with electroencephalography and electro‐oculography sensors have been developed. We evaluated the technical feasibility of a self‐applied electrode set from Nox Medical (Reykjavik, Iceland) through home sleep recordings of healthy and suspected sleep‐disordered adults ( n = 174) in the context of sleep staging. Subjects slept with a double setup of conventional type II polysomnography sensors and self‐applied forehead sensors. We found that the self‐applied electroencephalography and electro‐oculography electrodes had acceptable impedance levels but were more prone to losing proper skin–electrode contact than the conventional cup electrodes. Moreover, the forehead electroencephalography signals recorded using the self‐applied electrodes expressed lower litudes (difference 25.3%–43.9%, p 0.001) and less absolute power (at 1–40 Hz, p 0.001) than the polysomnography electroencephalography signals in all sleep stages. However, the signals recorded with the self‐applied electroencephalography electrodes expressed more relative power ( p 0.001) at very low frequencies (0.3–1.0 Hz) in all sleep stages. The electro‐oculography signals recorded with the self‐applied electrodes expressed comparable characteristics with standard electro‐oculography. In conclusion, the results support the technical feasibility of the self‐applied electroencephalography and electro‐oculography for sleep staging in home sleep recordings, after adjustment for litude differences, especially for scoring Stage N3 sleep.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 05-04-2020
DOI: 10.1007/S11325-020-02047-8
Abstract: Hypertension is a common finding in patients with obstructive sleep apnea (OSA), but it has remained unclear whether or not the amount of disturbed breathing and characteristics of in idual respiratory events differ between hypertensive and normotensive patients with severe OSA. Full polysomnographic recordings of 323 men and 89 women with severe OSA were analyzed. Differences in the duration of in idual respiratory events, total apnea and hypopnea times, and the percentage of disturbed breathing from total sleep time (AHT%) were compared between normotensive and hypertensive patients separately by genders. Furthermore, differences in the respiratory event characteristics were assessed between three AHT% groups (AHT% ≤ 30%, 30% AHT% ≤ 45%, and AHT% 45%). Hypertensive women had lower percentage apnea time (15.2% vs. 18.2%, p = 0.003) and AHT% (33.5% vs. 36.5%, p = 0.021) when compared with normotensive women. However, these differences were not observed between hypertensive and normotensive men. Percentage hypopnea time was higher in hypertensive men (13.5% vs. 11.2%, p = 0.043) but not in women (15.2% vs. 12.2%, p = 0.130) compared with their normotensive counterparts. The variation in AHI explained 60.5% ( ρ = 0.778) and 65.0% ( ρ = 0.806) of the variation in AHT% in normotensive and hypertensive patients, respectively. However, when AHT% increased, the capability of AHI to explain the variation in AHT% declined. There is a major inter- and intra-gender variation in percentage apnea and hypopnea times between hypertensive and normotensive patients with severe OSA. OSA is an important risk factor for hypertension and thus, early detection and phenotyping of OSA would allow timely treatment of patients with the highest risk of hypertension.
Publisher: Springer Science and Business Media LLC
Date: 06-06-2017
DOI: 10.1007/S11325-017-1513-6
Abstract: Frequency of apnea and hypopnea events is used to estimate the severity of obstructive sleep apnea (OSA). However, comprehensive information on whether apneas and hypopneas cause an equal biological effect is not available. The purpose of the present work was to evaluate the effect of the breathing cessation event type (i.e., obstructive apnea or hypopnea) and duration on the severity of related SpO Type 1 polysomnographies of 395 patients (220 males and 175 females) examined for suspected OSA were analyzed. Desaturation severity related to hypopnea and obstructive apnea events were compared and comparison was controlled for gender, sleep stage, sleeping position, age, and body mass index. Hypopneas and obstructive apneas were further ided into eight different durational categories and related desaturation event characteristics were compared between the categories. SpO Obstructive apneas led to more severe SpO
Publisher: Wiley
Date: 17-02-2023
DOI: 10.1111/JSR.13819
Abstract: There are concerns about the validation and accuracy of currently available consumer sleep technology for sleep‐disordered breathing. The present report provides a background review of existing consumer sleep technologies and discloses the methods and procedures for a systematic review and meta‐analysis of diagnostic test accuracy of these devices and apps for the detection of obstructive sleep apnea and snoring in comparison with polysomnography. The search will be performed in four databases (PubMed, Scopus, Web of Science, and the Cochrane Library). Studies will be selected in two steps, first by an analysis of abstracts followed by full‐text analysis, and two independent reviewers will perform both phases. Primary outcomes include apnea–hypopnea index, respiratory disturbance index, respiratory event index, oxygen desaturation index, and snoring duration for both index and reference tests, as well as the number of true positives, false positives, true negatives, and false negatives for each threshold, as well as for epoch‐by‐epoch and event‐by‐event results, which will be considered for the calculation of surrogate measures (including sensitivity, specificity, and accuracy). Diagnostic test accuracy meta‐analyses will be performed using the Chu and Cole bivariate binomial model. Mean difference meta‐analysis will be performed for continuous outcomes using the DerSimonian and Laird random‐effects model. Analyses will be performed independently for each outcome. Subgroup and sensitivity analyses will evaluate the effects of the types (wearables, nearables, bed sensors, smartphone applications), technologies (e.g., oximeter, microphone, arterial tonometry, accelerometer), the role of manufacturers, and the representativeness of the s les.
Start Date: 2021
End Date: 2025
Funder: European Commission
View Funded ActivityStart Date: 2020
End Date: 2021
Funder: Suomen Kulttuurirahasto
View Funded ActivityStart Date: 2019
End Date: 2020
Funder: Päivikki ja Sakari Sohlbergin Säätiö
View Funded ActivityStart Date: 2021
End Date: 2023
Funder: National Health and Medical Research Council
View Funded ActivityStart Date: 2019
End Date: 2022
Funder: Academy of Finland
View Funded ActivityStart Date: 2019
End Date: 2022
Funder: NordForsk
View Funded Activity