Detection of sleep disordered breathing and its central/obstructive character using nasal cannula and finger pulse oximeter

Obstructive sleep apnea diagnosis and beyond using portable monitors

Obstructive sleep apnea (OSA) is a chronic sleep and breathing disorder with significant health complications, including cardiovascular disease and neurocognitive impairments. To ensure timely treatment, there is a need for a portable, accurate and rapid method of diagnosing OSA. This review examines the use of various physiological signals used in the detection of respiratory events and evaluates their effectiveness in portable monitors (PM) relative to gold standard polysomnography. The primary objective is to explore the relationship between these physiological parameters and OSA, their application in calculating the apnea hypopnea index (AHI), the standard metric for OSA diagnosis, and the derivation of non-AHI metrics that offer additional diagnostic value. It is found that increasing the number of parameters in PMs does not necessarily improve OSA detection. Several factors can cause performance variations among different PMs, even if they extract similar signals. The review also highlights the potential of PMs to be used beyond OSA diagnosis. These devices possess parameters that can be utilized to obtain endotypic and other non-AHI metrics, enabling improved characterization of the disorder and personalized treatment strategies. Advancements in PM technology, coupled with thorough evaluation and validation of these devices, have the potential to revolutionize OSA diagnosis, personalized treatment, and ultimately improve health outcomes for patients with OSA. By identifying the key factors influencing performance and exploring the application of PMs beyond OSA diagnosis, this review aims to contribute to the ongoing development and utilization of portable, efficient, and effective diagnostic tools for OSA.

Correlation between Apnea Severity and Sagittal Cephalometric Features in a Population of Patients with Polysomnographically Diagnosed Obstructive Sleep Apnea

Background and Objective: Obstructive sleep apnea (OSA) is a sleep-related breathing disorder featuring a repeated closure of the upper airway during sleep. Craniofacial anatomy is a potential risk and worsening factor for OSA. This study aims to assess the relationship between cephalometric features of craniofacial morphology and OSA severity in a population of patients with OSA. Material and Methods: A sample of forty-two patients (n = 42, M = 76%, mean age = 57.8 ± 10.8) with a polysomnographically (PSG) confirmed diagnosis of OSA were recruited and underwent cephalometric evaluation of 16 cephalometric variables. In addition, the apnea−hypopnea index (AHI), oxygen desaturation (SatMin), Epworth sleepiness scale (ESS), and body mass index (BMI) were assessed. Then t-tests were performed to compare the values of all cephalometric variables between two AHI severity-based groups (mild-to-moderate = AHI ≤ 30; severe = AHI > 30). Single- and multiple-variable regression analyses were performed to assess the associations between AHI scores and cephalometric features. Results: Mean AHI, SatMin, and BMI were 31.4 ev/h, 78.7%, and 28.1, respectively. The cephalometric variables were not significantly different between the two OSA-severity groups (p > 0.05). Multiple-variable regression analyses showed that gonial angle and nasopharynx space were negatively associated with AHI, explaining 24.6% of the total variance. Conclusion: This investigation reported that severity of AHI scores in patients with OSA showed a negative correlation with gonial angle and nasopharynx space. As a general remark, although maxillofacial anatomy can be a predisposing factor for OSA, disease severity depends mainly upon other variables.

Multispectral Video Fusion for Non-Contact Monitoring of Respiratory Rate and Apnea

Continuous monitoring of respiratory activity is desirable in many clinical applications to detect respiratory events. Non-contact monitoring of respiration can be achieved with near- and far-infrared spectrum cameras. However, current technologies are not sufficiently robust to be used in clinical applications. For example, they fail to estimate an accurate respiratory rate (RR) during apnea. We present a novel algorithm based on multispectral data fusion that aims at estimating RR also during apnea. The algorithm independently addresses the RR estimation and apnea detection tasks. Respiratory information is extracted from multiple sources and fed into an RR estimator and an apnea detector whose results are fused into a final respiratory activity estimation. We evaluated the system retrospectively using data from 30 healthy adults who performed diverse controlled breathing tasks while lying supine in a dark room and reproduced central and obstructive apneic events. Combining multiple respiratory information from multispectral cameras improved the root mean square error (RMSE) accuracy of the RR estimation from up to 4.64 monospectral data down to 1.60 breaths/min. The median F1 scores for classifying obstructive (0.75 to 0.86) and central apnea (0.75 to 0.93) also improved. Furthermore, the independent consideration of apnea detection led to a more robust system (RMSE of 4.44 vs. 7.96 breaths/min). Our findings may represent a step towards the use of cameras for vital sign monitoring in medical applications.

Detecting central sleep apnea in adult patients using WatchPAT-a multicenter validation study

Study objectives

To assess the accuracy of WatchPAT (WP—Itamar-Medical, Caesarea, Israel) enhanced with a novel systolic upstroke analysis coupled with respiratory movement analysis derived from a dedicated snoring and body position (SBP) sensor, to enable automated algorithmic differentiation between central sleep apnea (CSA) and obstructive sleep apnea (OSA) compared with simultaneous in-lab sleep studies with polysomnography (PSG).

Methods

Eighty-four patients with suspected sleep-disordered breathing (SDB) underwent simultaneous WP and PSG studies in 11 sleep centers. PSG scoring was blinded to the automatically analyzed WP data.

Results

Overall WP apnea-hypopnea index (AHI; mean ± SD) was 25.2 ± 21.3 (range 0.2–101) versus PSG AHI 24.4 ± 21.2 (range 0–110) (p = 0.514), and correlation was 0.87 (p < 0.001). Using a threshold of AHI ≥ 15, the sensitivity and specificity of WP versus PSG for diagnosing sleep apnea were 85% and 70% respectively and agreement was 79% (kappa = 0.867). WP central AHI (AHIc) was 4.2 ± 7.7 (range 0–38) versus PSG AHIc 5.9 ± 11.8 (range 0–63) (p = 0.034), while correlation was 0.90 (p < 0.001). Using a threshold of AHI ≥ 15, the sensitivity and specificity of WP versus PSG for diagnosing CSA were 67% and 100% respectively with agreement of 95% (kappa = 0.774), and receiver operator characteristic (ROC) area under the curve of 0.866, (p < 0.01). Using a threshold of AHI ≥ 10 showed comparable overall sleep apnea and CSA diagnostic accuracies.

Conclusions

These findings show that WP can accurately detect overall AHI and effectively differentiate between CSA and OSA.

Reliability of autonomic activations as surrogates of cortical arousals in ventilated patients affected by amyotrophic lateral sclerosis

PURPOSE

The study aims to evaluate the performance of autonomic activations as a tool to assess sleep fragmentation and to recognize hypopneas in patients with amyotrophic lateral sclerosis (ALS) under non-invasive mechanical ventilation and secondarily, to evaluate, in patients with the same disease, the relationship between disruption of autonomic nervous system (ANS) activity and the usefulness of the autonomic activations as surrogates of cortical arousals.

METHODS

Sixteen ALS patients underwent simultaneous polysomnography and portable cardiorespiratory monitoring (PM). On the polysomnography, standard rules were used for scoring arousals and respiratory events. On the PM, autonomic arousals were scored as ≥ 15% heart rate (HR) increase with a ≥ 35% pulse wave amplitude (PWA) reduction, HR increase ≥ 20%, or PWA decrease ≥ 40%. Nocturnal HR variability was analyzed in the ALS patients and in 11 control subjects as an index of ANS activity.

RESULTS

Synchronized epoch by epoch analysis of the polysomnography and PM recordings showed that only 31.0 (22.5-58.7)% cortical and 36.1 (20.5-47.2)% autonomic arousals were associated with one another. Among hypopneas scored at polysomnography, 71.7% were associated with a cortical arousal but not with a desaturation. On average, HR variability in ALS showed signs of depressed ANS activity that was particularly evident in the patients where the cortical arousals exceeded the autonomic ones.

CONCLUSIONS

In ventilated ALS patients, autonomic activations may hardly have a role as surrogates of cortical arousals for assessment of sleep fragmentation and for respiratory scoring. Depression of ANS activity may be related to their poor performance.

Validation of a photoplethysmography device for detection of obstructive sleep apnea in the perioperative setting

Obstructive sleep apnea (OSA) is a risk factor for perioperative complications, but many OSA patients present undiagnosed. While polysomnography (PSG) is the "gold standard" for diagnosis, its application is technology-intense, time-consuming, expensive, and requires specialists, often delaying surgery. Thus, miniaturized devices were developed for OSA screening aimed at ruling out major OSA while measuring a lesser number of biological signals. We evaluated the accuracy of a photoplethysmography (PPG)-based device for OSA detection. 48 patients with established or strongly suspected (STOP-Questionnaire) OSA scheduled for surgery underwent in their preoperative nights parallel recordings by PPG and a classic polygraphy (PG) devices (SomnoLab2®). We compared the diagnostic accuracy of the PPG in diagnosing mild [Apnea-/Hypopnea-Index (AHI) 5-14 events/h] and moderate-to-severe OSA (AHI > 15). PPG and PG-derived AHI correlated significantly (r = 0.85, p < 0.0001) and high area under curve (AUC) in receiver operator characteristics (ROC) values were seen for both AHI thresholds (0.93 and 0.95, respectively). For an AHI > 5, sensitivity was 100%, specificity 44%, positive predictive value (PPV) 62%, negative predictive value (NPV) 100%, likelihood ratio (LHR) 1.79, and Cohen κ was 0.43. For an AHI > 15, sensitivity was 92%, specificity 77%, PPV 60%, NPV 96%, LHR 4.04, and Cohen κ was 0.59. In a typical perioperative cohort of confirmed and suspected OSA patients, PPG reliably detected OSA patients while showing some false-positive results. Such devices are helpful for preoperative OSA screening.

Pediatric sleep-disordered breathing: an update on diagnostic testing

PURPOSE OF REVIEW

Recent advances in diagnostic testing for obstructive sleep apnea in children have refined the standard tests while identifying several new tools that hold promise to radically change how we diagnose sleep apnea.

RECENT FINDINGS

Studies have demonstrated that the polysomnogram may be modified to permit home assessment of sleep disturbed breathing in children to ensure more widespread access to the test. Alternately, questionnaires, nocturnal oximetry, and diagnostic urinary biomarkers have shown great promise as both sensitive and specific tools to diagnose sleep apnea in children as well as track the severity of the disease.

SUMMARY

The gold standard polysomnogram has been refined to permit its application in a modified form at home and for brief examinations in children. This standard has been challenged on several fronts, including questionnaires, nocturnal oximetry, drug-induced sleep endoscopy, and noninvasive urinary biomarkers that may ultimately supplant polysomnography as the gold standard to diagnose obstructive sleep apnea syndrome in children.

A novel postal-based approach to diagnosing obstructive sleep apnoea in a high-risk population

OBJECTIVE

More than 50% of patients with diabetic macular oedema (DMO) have obstructive sleep apnoea (OSA), but the majority remain undiagnosed. We used a four-channel device (ApneaLink [AL], ResMed, UK) to establish a remote postal-based diagnostic service for patients with DMO. Here we describe our experience.

METHODS

Patients with DMO were invited to participate. Interested patients returned a free-post reply slip to the study team, who posted an AL with pictorial and written instructions to them. Following a single night study, the AL was returned by a freepost service.

RESULTS

Responses from 733 patients meeting the inclusion criteria were received, comprising 469 males and 264 females, mean age 64 years (standard deviation 10.4 years). ALs were issued to 718 patients, of whom 606 completed a diagnostic study. A total of 71 patients (12%) required a repeat study due to inadequacy of the first attempt. Completed sleep studies showed that 75% of respondents had sleep disordered breathing: 4% ODI 0-4/h, 24%; 5-9/h, 19%; 10-19/h, 23%; ≥20/h, 34%; and AHI 0-4/h, 25%; 5-14/h, 38%; 15-29/h, 20%; ≥30/h, 17%. Among 1592 postal events through the national post service, 20 ALs were lost.

CONCLUSIONS

We have demonstrated that a remote postal-based diagnostic service for populations with a high risk of OSA can be successfully performed. This novel approach, which avoids clinic attendance, may be useful in clinical practice.

Speckle tracking echocardiography in chronic obstructive pulmonary disease and overlapping obstructive sleep apnea

Background

COPD and congestive heart failure represent two disease entities of growing global burden that share common etiological features. Therefore, we aimed to identify the degree of left ventricular (LV) dysfunction in COPD as a function of COPD severity stages and concurrently placed particular emphasis on the presence of overlapping obstructive sleep apnea (OSA).

Methods

A total of 85 COPD outpatients (64.1±10.4 years, 54.1% males) and 20 controls, matched for age, sex, and smoking habits, underwent speckle tracking echocardiography for LV longitudinal strain imaging. Complementary 12-lead electrocardiography, laboratory testing, and overnight screening for sleep-disordered breathing using the SOMNOcheck micro^® device were performed.

Results

Contrary to conventional echocardiographic parameters, speckle tracking echocardiography revealed significant impairment in global LV strain among COPD patients compared to control smokers (−13.3%±5.4% vs −17.1%±1.8%, P=0.04). On a regional level, the apical septal LV strain was reduced in COPD (P=0.003) and associated with the degree of COPD severity (P=0.02). With regard to electrocardiographic findings, COPD patients exhibited a significantly higher mean heart rate than controls (71.4±13.0 beats per minute vs 60.3±7.7 beats per minute, P=0.001) that additionally increased over Global Initiative for Chronic Obstructive Lung Disease stages (P=0.01). Albeit not statistically significant, COPD led to elevated N-terminal pro-brain natriuretic peptide levels (453.2±909.0 pg/mL vs 96.8±70.0 pg/mL, P=0.08). As to somnological testing, the portion of COPD patients exhibiting overlapping OSA accounted for 5.9% and did not significantly vary either in comparison to controls (P=0.07) or throughout the COPD Global Initiative for Chronic Obstructive Lung Disease stages (P=0.49). COPD-OSA overlap solely correlated with nocturnal hypoxemic events, whereas LV performance status was unrelated to coexisting OSA.

Conclusion

To conclude, COPD itself seems to be accompanied with decreased LV deformation properties that worsen over COPD severity stages, but do not vary in case of overlapping OSA.

Use of a portable monitoring device (Somnocheck Micro) for the investigation and diagnosis of obstructive sleep apnoea in comparison with polysomnography

OBJECTIVE

Polysomnography (PSG) remains the gold standard for the diagnosis of obstructive sleep apnoea syndrome (OSAS). While PSG is essential for OSAS, this technique is not suitable for epidemiological investigation due to its high cost. This study aimed to compare a portable monitoring device with PSG for the measurement of parameters related to the diagnosis of OSAS in rural areas.

METHODS

We conducted a descriptive study of 155 patients (30 women and 125 men; mean age, 52±12years) who visited to the Hendek Government Hospital Sleep Laboratory between February 2011 and January 2013 Apnoea hypopnea index (AHI), mean levels of O2 (meanO2), desaturation index (DI), and minimum oxygen saturation (minO2) variations as measured using both PSG and a portable Somnocheck Micro (SM) device were compared.

RESULTS

Differences were found between the meanO2 and DI, but not between AHI and minO2. Differences between the methods were not desired, but the relationship between the methods was distinct and supported our hypothesis.

CONCLUSIONS

The results of our study have shown that the SM portable device can be used as an alternative diagnostic tool in this population either at home or in sleep clinic.

Computer-Assisted Diagnosis of the Sleep Apnea-Hypopnea Syndrome: A Review

Automatic diagnosis of the Sleep Apnea-Hypopnea Syndrome (SAHS) has become an important area of research due to the growing interest in the field of sleep medicine and the costs associated with its manual diagnosis. The increment and heterogeneity of the different techniques, however, make it somewhat difficult to adequately follow the recent developments. A literature review within the area of computer-assisted diagnosis of SAHS has been performed comprising the last 15 years of research in the field. Screening approaches, methods for the detection and classification of respiratory events, comprehensive diagnostic systems, and an outline of current commercial approaches are reviewed. An overview of the different methods is presented together with validation analysis and critical discussion of the current state of the art.

Underdiagnosis of Obstructive Sleep Apnoea in Peripheral Arterial Disease

Background: Obstructive sleep apnoea (OSA) has interdependently been related to the onset and progression of a large portion of atherosclerotic cardiovascular disorders. In due consideration of OSA-mediated endothelial dysfunction, its impact on peripheral artery disease is conceivable, but undefined. Objectives: The aim of this study was to identify the prevalence of OSA in a lower extremity artery disease (LEAD) study population. Methods: A total of 91 patients receiving in- and outpatient treatment for LEAD were included in this prospectively conducted trial. In addition to an angiological examination, all patients underwent nocturnal screening for sleep-disordered breathing by use of SOMNOcheck micro® (SC micro) and - depending on the results obtained - polysomnography. Results: Patients were principally late middle-aged (69.3 ± 10.8 years), male (71.4%) and slightly overweight (BMI 26.8 ± 3.9). Overnight screening determined a sleep apnoea prevalence of 78.0%, of which 90.1% exhibited a predominantly obstructive genesis. The mean apnoea-hypopnoea index (AHI; events/h) and oxygen desaturation index (events/h) averaged 11.8 ± 13.4 and 8.9 ± 14.2, respectively. The individual AHI categories of non-pathological (<5), mild (5 to <15), moderate (15 to <30) and severe sleep apnoea (≥30) accounted for 22.0, 59.3, 13.2 and 5.5%, respectively. A distributive examination of AHI within LEAD severity groups evinced a significant association (p = 0.047). In cases of at least moderate sleep apnoea (AHI ≥15) polysomnography was performed (n = 17, 18.7% of the whole collective). Correlative analysis revealed a significant correlation between values obtained by SC micro recording and polysomnography, establishing the diagnostic accuracy of the screening results. Conclusions: OSA exhibits an important prevalence of 70.3% in LEAD patients with prior undiagnosed sleep-disordered breathing, indicating major OSA unawareness in this cardiovascular cohort. However, the impact of OSA treatment on LEAD propagation remains to be determined. © 2015 S. Karger AG, Basel.

Overnight pulse oximetry for evaluation of sleep apnea among children with trisomy 21

STUDY OBJECTIVES

For children with trisomy 21, polysomnography at age 4 to assess obstructive sleep disordered breathing (OSDB) is the standard of care. Oximetry alone has been used to screen for disease among children without trisomy 21. This study evaluates the potential usefulness of oximetry scoring in diagnosing OSDB among children with trisomy 21.

METHODS

A McGill oximetry score from 1 to 4 was derived from a full overnight PSG done on 119 consecutive pediatric subjects with trisomy 21. Most were referred to the sleep laboratory because of suspicion for OSDB. Oximetry scorers were blinded to the child's full PSG and clinical course. Results of the complete PSG were then compared to oximetry scores.

RESULTS

Obstructive apnea-hypopnea index (OAHI) was ≥ 2.5 for 50% of all subjects. Fifty-nine subjects (49.6%) had McGill Score 1 ("inconclusive"); median OAHI was 1.0 (IQR 0.4-3.3). McGill Score was 2 for 43 subjects (36.1%); median OAHI was 4.5 (IQR 1.3-8.8). Seventeen subjects (14.3%) had McGill Scores of 3 or 4; median OAHI was 16.1 (IQR 9.3-45.5, range 2.1 to 101.1). Ten percent of subjects had a considerable number of central events (≥ 2.5 respiratory events/h but OAHI < 2.5), including 7 with McGill Score 2.

CONCLUSIONS

In a retrospective cohort of children with trisomy 21, McGill oximetry scores of 3 or 4 reliably identified patients with marked OSDB. The possibility of central apneas causing hypoxemia must be considered in those with McGill Score 2. With these caveats, oximetry screening should be considered when developing streamlined protocols for early intervention to treat OSDB in this population.

The Effect of the Transition to Home Monitoring for the Diagnosis of OSAS on Test Availability, Waiting Time, Patients' Satisfaction, and Outcome in a Large Health Provider System

During 2009, the Haifa district of Clalit Health Services (CHS) has switched from in-lab polysomnography (PSG) to home studies for the diagnosis of obstructive sleep apnea (OSA). We assessed the effects of this change on accessibility, waiting time, satisfaction, costs, and CPAP purchase by the patients. Data regarding sleep studies, CPAP purchase, and waiting times were collected retrospectively from the computerized database of CHS. Patients' satisfaction was assessed utilizing a telephone questionnaire introduced to a randomized small sample of 70 patients. Comparisons were made between 2007 and 2008 (in-lab PSGs) and 2010 and 2011 (when most studies were ambulatory). Of about 650000 insured individuals in the Haifa district of CHS, 1471 sleep studies were performed during 2007-2008 compared to 2794 tests during 2010-2011. The average waiting time was 9.9 weeks in 2007-2008 compared to 1.1 weeks in 2010-2011 (P < 0.05). 597 CPAPs were purchased in 2007-2008 compared to 831 in 2010-2011. The overall patients' satisfaction was similar, but discomfort tended to be higher in the in-laboratory group (4.1 vs 2.7 in a scale of 0-10; P = 0.11). Switching to ambulatory diagnosis improved the test accessibility and reduced the waiting times. Patients' satisfaction remained similarly high. The total direct cost of OSA management was reduced.