Impact of different criteria for defining hypopneas in the apnea-hypopnea index

Association of cortical arousals with sleep-disordered breathing events

STUDY OBJECTIVES

The American Academy of Sleep Medicine recommends scoring hypopneas in adults when there is a ≥ 3% oxygen desaturation or when the event is associated with an arousal. However, there is no rule regarding the duration of the interval between the event termination and the associated arousal. The purpose of this study is to explore the timing between arousals and sleep-disordered breathing (SDB) events.

METHODS

We analyzed cortical arousals (> 1.6 million) and SDB events (> 350,000 apneas and > 1.9 million hypopneas) from 11,400 manually scored polysomnography recordings. Only arousals that started within ±30 seconds from the end of SDB events were included. We used the 2 local minimums on either side of the arousal distribution as the start/end times for the distribution and to define which arousals are associated with SDB events. Finally, we calculated arousal probability near the end of SDB events.

RESULTS

Cortical arousals with start times that fell within the 2 minimums were considered to be associated with SDB events. Using this definition, we found that 90% of apnea-associated arousals started no earlier than 4 seconds before and no later than 9 seconds after the end of apneas. Similarly, 90% of hypopnea-associated arousals started no earlier than 6 seconds before and no later than 14 seconds after the end of hypopneas, with the peak of the distribution coinciding with event end time. Arousal probability was highest during the first 10 seconds after the end of the event and was higher for longer events.

CONCLUSIONS

Our results suggest that 90% of SDB-associated arousals start no earlier than 6 seconds before and no later than 14 seconds after the end of the respiratory events.

CITATION

Zitting K-M, Lockyer BJ, Azarbarzin A, et al. Association of cortical arousals with sleep-disordered breathing events. J Clin Sleep Med. 2023;19(5):899-912.

Diet-induced obesity leads to sleep fragmentation independently of the severity of sleep-disordered breathing

Obesity is associated with sleep-disordered breathing (SDB) and unrefreshing sleep. Residual daytime sleepiness and sleep impairments often persist after SDB treatment in patients with obesity, which suggests an independent effect of obesity on breathing and sleep. However, examining the relationship between sleep architecture and SDB in patients with obesity is complex and can be confounded by multiple factors. The main goal of this study was to examine the relationship between obesity-related changes in sleep architecture and SDB. Sleep recordings were performed in 15 lean C57BL/6J and 17 diet-induced obesity (DIO) mice of the same genetic background. Arousals from sleep and apneas were manually scored. Respiratory arousals were classified as events associated with ≥30% drops in minute ventilation (VE) from baseline. We applied Poincaré analysis of VE during sleep to estimate breathing variability. Obesity augmented the frequency of arousals by 45% and this increase was independent of apneas. Respiratory arousals comprised only 15% of the arousals in both groups of mice. Breathing variability during non-rapid-eye-movment (NREM) sleep was significantly higher in DIO mice, but it was not associated with arousal frequency. Our results suggest that obesity induces sleep fragmentation independently of SDB severity.NEW & NOTEWORTHY Our diet-induced obesity (DIO) model reproduces sleep features of human obesity, including sleep fragmentation, increased apnea frequency, and larger breathing variability. DIO induces sleep fragmentation independently of apnea severity. Sleep fragmentation in DIO mice is mainly attributed to non-respiratory arousals. Increased breathing variability during sleep did not account for the higher arousal frequency in DIO. Our results provide a rationale to examine sleep in patients with obesity even when they are adequately treated for sleep-disordered breathing.

Improving outcomes of hypoglossal nerve stimulation therapy: current practice, future directions and research gaps. Proceedings of the 2019 International Sleep Surgery Society Research Forum

Hypoglossal nerve stimulation (HGNS) has evolved as a novel and effective therapy for patients with moderate-to-severe obstructive sleep apnea (OSA). Despite positive published outcomes of HGNS, there exist uncertainties regarding proper patient selection, surgical technique, and the reporting of outcomes and individual factors that impact therapy effectiveness. According to current guidelines, this therapy is indicated for select patients, and recommendations are based on the Stimulation Therapy for Apnea Reduction (STAR) trial. Ongoing research and physician experiences continuously improve methods to optimize the therapy. An understanding of the way in which airway anatomy, OSA phenotypes, individual health status, psychological conditions and comorbid sleep disorders influence the effectiveness of HGNS is essential to improve outcomes and expand therapy indications. This manuscript presents discussions on current evidence, future directions, and research gaps for HGNS therapy from the 10th International Surgical Sleep Society expert research panel.

Effect of Varying Definitions of Hypopnea on the Diagnosis and Clinical Outcomes of Sleep-Disordered Breathing: A Systematic Review and Meta-Analysis

STUDY OBJECTIVES

Various criteria have been used for scoring hypopneas, leading to difficulties when comparing results in clinical and research settings. We conducted a systematic review and meta-analysis to assess the effect of different hypopnea definitions on the diagnosis, severity, and clinical implications of sleep-disordered breathing (SDB).

METHODS

Ovid MEDLINE, Embase, and Scopus databases were queried for English-language publications from inception through March 7, 2017. Studies that directly compared various hypopnea definitions were eligible. The hierarchical summary receiver operating characteristic model was used to jointly estimate diagnostic performance for comparisons between criteria.

RESULTS

The initial search yielded 2,828 abstracts; 28 met inclusion criteria. After reviewing reference lists and expert review, five additional articles were identified. Most of the studies were cross-sectional or retrospective in nature. Eleven studies compared 2007 recommended criteria with 2012 criteria; 6 of these (evaluating 6,628 patients) were suitable for inclusion in the meta-analysis. Using the 2012 definition (≥ 3% desaturation or arousal) as the reference standard, the 2007 definition (≥ 4% desaturation) showed a sensitivity of 82.7% (95% confidence interval 0.72-0.90) and specificity of 93.2% (95% confidence interval 0.82-0.98). Although 2007 criteria were found to be associated with prevalent cardiovascular (CV) disease and increased risk of CV death, the 2012 criteria appeared to correspond better with intermediate CV risk markers based on two abstracts.

CONCLUSIONS

As expected, 2012 hypopnea scoring criteria resulted in a greater prevalence and severity of SDB. Data regarding the effect of varying hypopnea definitions on clinical outcomes, quality of life, health care costs, and mortality rates are limited.

COMMENTARY

A commentary on this article appears in this issue on page 683.

Effect of Three Hypopnea Scoring Criteria on OSA Prevalence and Associated Comorbidities in the General Population

STUDY OBJECTIVES

Apnea-hypopnea index (AHI) is the main polysomnographic measure to diagnose obstructive sleep apnea (OSA). We aimed to evaluate the effect of three standard hypopnea definitions on the prevalence of OSA and its association with cardiometabolic outcomes in the general population.

METHODS

We analyzed data from the HypnoLaus study (Lausanne, Switzerland), in which 2,162 participants (51% women, 57 ± 19 years) underwent in-home full polysomnography. AHI was calculated using three hypopnea definitions: AASM₁₉₉₉ (≥ 50% decrease in airflow or lower airflow reduction associated with oxygen desaturation ≥ 3% or an arousal), AASM₂₀₀₇ (≥ 30% airflow reduction associated with ≥ 4% oxygen desaturation), and AASM_{2012 (≥} 30% airflow reduction associated with ≥ 3% oxygen desaturation or an arousal). Participants underwent clinical assessment for hypertension, diabetes, and metabolic syndrome.

RESULTS

Median AHI of AASM₁₉₉₉, AASM₂₀₀₇ and AASM₂₀₁₂ criteria were 10.9, 4.4, and 10.1 events/h, respectively. OSA prevalence defined as AHI ≥ 5, ≥ 15, and ≥ 30 events/h was 74.5%, 39.3%, and 16.3% using AASM₁₉₉₉; 46.9%, 18.8%, and 6.8% using AASM₂₀₀₇; and 72.2%, 36.6%, and 14.9% using AASM₂₀₁₂. Different AHI thresholds derived from AASM₁₉₉₉, AASM₂₀₀₇, and AASM₂₀₁₂ criteria_, respectively, were associated with hypertension (11.5, 4.8, 10.7 events/h), diabetes (15.7, 7.1, 14.4 events/h), and metabolic syndrome (12.8, 5.5, 11.8 events/h).

CONCLUSIONS

Hypopnea definition has a major effect on AHI and on OSA prevalence in the general population and, hence, important implications for public health policies. There is a twofold difference in the threshold above which an association with diabetes, hypertension, and metabolic syndrome is observed using AASM₂₀₀₇ compared to AASM₁₉₉₉ or AASM₂₀₁₂ criteria.

Varying Hypopnea Definitions Affect Obstructive Sleep Apnea Severity Classification and Association With Cardiovascular Disease

STUDY OBJECTIVES

To compare clinical features and cardiovascular risks in patients with obstructive sleep apnea (OSA) based on ≥ 3% desaturation or arousal, and ≥ 4% desaturation hypopnea criteria.

METHODS

This is a cross-sectional analysis of 1,400 veterans who underwent polysomnography for suspected sleep-disordered breathing. Hypopneas were scored using ≥ 4% desaturation criteria per the American Academy of Sleep Medicine (AASM) 2007 guidelines, then re-scored using ≥ 3% desaturation or arousal criteria per AASM 2012 guidelines. The effect on OSA disease categorization by these two different definitions were compared and correlated with symptoms and cardiovascular associations using unadjusted and adjusted logistic regression.

RESULTS

The application of the ≥ 3% desaturation or arousal definition of hypopnea captured an additional 175 OSA diagnoses (12.5%). This newly diagnosed OSA group (OSA_new) was symptomatic with daytime sleepiness similarly to those in whom OSA had been diagnosed based on ≥ 4% desaturation criteria (OSA_4%). The OSA_new group was more obese and more likely to be male than those without OSA based on either criterion (No-OSA). However, the OSA_new group was younger, less obese, more likely female, and had a lesser smoking history compared to the OSA_4% group. Those with any severity of OSA_4% had an increased adjusted odds ratio for arrhythmias (odds ratio = 1.95 [95% confidence interval 1.37-2.78], P = .0155). The more inclusive hypopnea definition (ie, ≥ 3% desaturation or arousal) resulted in recategorization of OSA diagnosis and severity, and attenuated the increased odds ratio for arrhythmias observed in mild and moderate OSA_4%. However, severe OSA based on ≥ 3% desaturation or arousals (OSA3%/Ar) remained a significant risk factor for arrhythmias. OSA based on any definition was not associated with ischemic heart disease or heart failure.

CONCLUSIONS

The most current AASM criteria for hypopnea identify a unique group of patients who are sleepy, but who are not at increased risk for cardiovascular disease. Though the different hypopnea definitions result in recategorization of OSA severity, severe disease whether defined by ≥ 3% desaturation/arousals or ≥ 4% desaturation remains predictive of cardiac arrhythmias.

COMMENTARY

A commentary on this article appears in this issue on page 1971.

Arousal responses to respiratory events during sleep: the role of pulse wave amplitude

The study aims at assessing the changes in electroencephalography (as measured by the A-phases of cyclic alternating pattern) and autonomic activity (based on pulse wave amplitude) at the recovery of airway patency in patients with obstructive sleep apnea syndrome. Analysis of polysomnographic recordings from 20 male individuals with obstructive sleep apnea syndrome was carried out in total sleep time, non-rapid eye movement and rapid eye movement sleep. Scoring quantified the combined occurrence (time range of 4 s before and 4 s after respiratory recovery) or separate occurrence of A-phases (cortical activation), and pulse wave amplitude drops (below 30%) to apneas, hypopneas or flow limitation events. A dual response (A-phase associated with a pulse wave amplitude drop) was the most frequent response (71.8% in total sleep time) for all types of respiratory events, with a progressive reduction from apneas to hypopneas and flow limitation events. The highly significant correlation in total sleep time (r = 0.9351; P < 0.0001) between respiratory events combined with A-phases and respiratory events combined with pulse wave amplitude drops was confirmed both in non-rapid eye movement (r = 0.9622; P < 0.0001) and rapid eye movement sleep (r = 0.7162; P < 0.0006). In conclusion, a dual cortical and autonomic activation is the most common manifestation at the recovery of airway patency. The significant correlation between A-phases and relevant pulse wave amplitude drops suggests a possible role of pulse wave amplitude as a marker of cerebral response to respiratory events.

Pathway for the Management of Sleep Apnea in the Cardiac Patient

Sleep-disordered breathing is a highly prevalent medical condition, which if undiagnosed leads to increased morbidity and mortality, particularly related to increased incidence of cardiovascular events. It is therefore imperative that we identify patient population at high risk for sleep apnea and refer them to the appropriate therapy as early as possible. Up-to-date there is no management guideline specifically geared towards cardiac patients. Thus, we propose a (SAP) Sleep Apnea Pathway to correctly identify and triage these patients to the appropriate therapy.

Calibration Model for Apnea-Hypopnea Indices: Impact of Alternative Criteria for Hypopneas

STUDY OBJECTIVE

To characterize the association among apnea-hypopnea indices (AHIs) determined using three common metrics for defining hypopnea, and to develop a model to calibrate between these AHIs.

DESIGN

Cross-sectional analysis of Sleep Heart Health Study Data.

SETTING

Community-based.

PARTICIPANTS

There were 6,441 men and women age 40 y or older.

MEASUREMENT AND RESULTS

Three separate AHIs have been calculated, using all apneas (defined as a decrease in airflow greater than 90% from baseline for ≥ 10 sec) plus hypopneas (defined as a decrease in airflow or chest wall or abdominal excursion greater than 30% from baseline, but not meeting apnea definitions) associated with either: (1) a 4% or greater fall in oxyhemoglobin saturation-AHI4; (2) a 3% or greater fall in oxyhemoglobin saturation-AHI3; or (3) a 3% or greater fall in oxyhemoglobin saturation or an event-related arousal-AHI3a. Median values were 5.4, 9.7, and 13.4 for AHI4, AHI3, and AHI3a, respectively (P < 0.0001). Penalized spline regression models were used to compare AHI values across the three metrics and to calculate prediction intervals. Comparison of regression models demonstrates divergence in AHI scores among the three methods at low AHI values and gradual convergence at higher levels of AHI.

CONCLUSIONS

The three methods of scoring hypopneas yielded significantly different estimates of the apnea-hypopnea index (AHI), although the relative difference is reduced in severe disease. The regression models presented will enable clinicians and researchers to more appropriately compare AHI values obtained using differing metrics for hypopnea.

The effect of adding gender item to Berlin Questionnaire in determining obstructive sleep apnea in sleep clinics

BACKGROUND AND AIM

We aimed to validate the Turkish version of Berlin Questionnaire (BQ) and developped a BQ-gender (BQ-G) form by adding gender component. We aimed to compare the two forms in defining patients with moderate to severe obstructive sleep apnea (OSA) in sleep clinics.

METHODS

Four hundred and eighty five consecutive patients, refered to our sleep clinic for snoring, witnessed apnea and/or excessive daytime sleepiness were enrolled to the study. All patients underwent in-laboratory polysomnography (PSG). Patients with sleep efficiency less than 40% and total sleep time less than 4 hours, chronic anxiolitic/sedative drug usage, respiratory tract infection within past two weeks were excluded from the study. All the patients fulfilled BQ. The test and retest for BQ were applied in 15-day interval in 30 patients.

RESULTS

Totally 433 patients were enrolled to the study (285 male, 148 female). The mean age of the patients was 47,5 ± 10.5 (21-79). 180 patients (41.6%) had apnea-hypopnea index (AHI) ≤ 15, while 253 patients (58,4%) had AHI > 15. The κ value was 48-94 and the the truth value was 69-94% for the test-retest procedure. Sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and area under the curve AUC were 84.2%, 31.7%, 48.7%, 63.4%, and 0.579 in order for BQ and 79.9 %, 51.7%, 63.2% , 69.6%, and 0.652 for BQ-G.

CONCLUSION

The results showed that BQ-G is relatively better than BQ in determining moderate to severe OSA in sleep clinics where most of the patients are sleep apneic but both of the tests were found to have insufficient validities in defining moderate to severe OSA in sleep clinics.

A comparison between the AASM 2012 and 2007 definitions for detecting hypopnea

PURPOSE

To compare the apnea-hypopnea indices (AHIs) derived using three hypopnea definitions published by the American Academy of Sleep Medicine (AASM) and to determine the impact of the new modifications of the definition on AHIs and the diagnosis of obstructive sleep apnea (OSA).

METHODS

The study comprised 100 consecutive patients who were investigated for OSA using overnight diagnostic polysomnography (PSG). The hypopneas were scored in three passes by two certified sleep technologists; in the first pass, the hypopneas were scored using the 2007 AASM "Alternative" (H Alt) criteria. In the second pass, the hypopneas were scored using the 2007 AASM "Recommended" (H Rec) criteria. In the third pass, the hypopneas were scored according to the new AASM "2012" (H 2012) criteria. Agreement analysis of the results obtained using the three scoring criteria was performed using the Bland-Altman plot methodology.

RESULTS

The studied group had a mean age of 45.5±12.6 years and a body mass index of 30.2±5.8 kg/m2. Using the H 2012, H Rec and H Alt criteria, the AHIs were 37.9±27.6, 14.8±22.4 and 29.6±27.0/h, respectively (p<0.05). The Bland-Altman analysis of the AHI demonstrated that more events were nearly always detected using the H 2012 definition.

CONCLUSION

A significant difference in detecting hypopnea events exists among the H 2012, H Rec and H Alt definitions. The 2007 AASM "Recommended" definition tended to result in lower AHI than the other two definitions.

Epidemiology of Obstructive Sleep Apnea: a Population-based Perspective

This review summarizes the recent literature on the epidemiology of adult obstructive sleep apnea (OSA) from various population-based studies. Despite methodologic differences, comparisons have yielded similar prevalence rates of the OSA syndrome in various geographic regions and amongst a number of ethnic groups. Risk factors for OSA including obesity, aging, gender, menopause, and ethnicity are analyzed. We also provide discussion on adverse medical conditions associated with OSA including hypertension, stroke, congestive heart failure, coronary artery disease, cardiovascular mortality, insulin resistance, and neurocognitive dysfunction. Finally with the progression of the global obesity epidemic, we focus on the economic health care burden of OSA and the importance of recognizing the largely undiagnosed OSA population with emphasis on strategies to improve access to diagnostic resources.

Envelope analysis of the airflow signal to improve polysomnographic assessment of sleep disordered breathing

STUDY OBJECTIVES

Given the detailed respiratory waveform signal provided by the nasal cannula in polysomnographic (PSG) studies, to quantify sleep breathing disturbances by extracting a continuous variable based on the coefficient of variation of the envelope of that signal.

DESIGN

Application of an algorithm for envelope analysis to standard nasal cannula signal from actual polysomnographic studies.

SETTING

PSG recordings from a sleep disorders center were analyzed by an algorithm developed on the Igor scientific data analysis software.

PATIENTS OR PARTICIPANTS

Recordings representative of different degrees of sleep disordered breathing (SDB) severity or illustrative of the covariation between breathing and particularly relevant factors and variables.

INTERVENTIONS

The method calculated the coefficient of variation of the envelope for each 30-second epoch. The normalized version of that coefficient was defined as the respiratory disturbance variable (RDV). The method outcome was the all-night set of RDV values represented as a time series.

MEASUREMENTS AND RESULTS

RDV quantitatively reflected departure from normal sinusoidal breathing at each epoch, providing an intensity scale for disordered breathing. RDV dynamics configured itself in recognizable patterns for the airflow limitation (e.g., in UARS) and the apnea/hypopnea regimes. RDV reliably highlighted clinically meaningful associations with staging, body position, oximetry, or CPAP titration.

CONCLUSIONS

Respiratory disturbance variable can assess sleep breathing disturbances as a gradual phenomenon while providing a comprehensible and detailed representation of its dynamics. It may thus improve clinical diagnosis and provide a revealing descriptive tool for mechanistic sleep disordered breathing modeling. Respiratory disturbance variable may contribute to attaining simplified screening methodologies, novel diagnostic criteria, and insightful research tools.

The effect of respiratory scoring on the diagnosis and classification of sleep disordered breathing in chronic heart failure

STUDY OBJECTIVES

To evaluate the effect of respiratory scoring criteria on diagnosis and classification of sleep disordered breathing (SDB) in chronic heart failure (CHF).

DESIGN

Cross-sectional observational study.

SETTING

Heart failure and general cardiology clinics at two London hospitals.

PATIENTS OR PARTICIPANTS

One hundred eighty stable patients with CHF and a median age of 69.6 y, 86% male.

INTERVENTIONS

SDB was diagnosed by polysomnography. The apnea-hypopnea index (AHI) was initially scored using a conservative hypopnea definition of a ≥ 50% decrease in nasal airflow with a ≥ 4% oxygen desaturation. The AHI was rescored with hypopnea defined according to the American Academy of Sleep Medicine (AASM) alternative scoring rule, requiring an associated ≥ 3% oxygen desaturation or arousal. SDB was defined as AHI ≥ 15/h. Diagnosis and classification of SDB as obstructive sleep apnea (OSA) or central sleep apnea (CSA) with each rule were compared. The effect of mixed apneas on classification of SDB as CSA or OSA was also investigated.

MEASUREMENTS AND RESULTS

Median AHI increased from 9.3/h to 13.8/h (median difference 4.6/h) when the AASM alternative rule was used to score hypopneas. SDB prevalence increased from 29% to 46% with the alternative scoring rule (P < 0.001). Classification of SDB as OSA or CSA was not significantly altered by hypopnea scoring rules or the categorization of mixed apneas.

CONCLUSION

Hypopnea scoring rules can significantly influence the apnea-hypopnea index and diagnosis of sleep disordered breathing in chronic heart failure but do not alter the classification as obstructive sleep apnea or central sleep apnea. Standardization of hypopnea scoring rules is important to ensure consistency in diagnosis of sleep disordered breathing in chronic heart failure patients.

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

RATIONALE

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Rules for scoring respiratory events in sleep: update of the 2007 AASM Manual for the Scoring of Sleep and Associated Events. Deliberations of the Sleep Apnea Definitions Task Force of the American Academy of Sleep Medicine

The American Academy of Sleep Medicine (AASM) Sleep Apnea Definitions Task Force reviewed the current rules for scoring respiratory events in the 2007 AASM Manual for the Scoring and Sleep and Associated Events to determine if revision was indicated. The goals of the task force were (1) to clarify and simplify the current scoring rules, (2) to review evidence for new monitoring technologies relevant to the scoring rules, and (3) to strive for greater concordance between adult and pediatric rules. The task force reviewed the evidence cited by the AASM systematic review of the reliability and validity of scoring respiratory events published in 2007 and relevant studies that have appeared in the literature since that publication. Given the limitations of the published evidence, a consensus process was used to formulate the majority of the task force recommendations concerning revisions.The task force made recommendations concerning recommended and alternative sensors for the detection of apnea and hypopnea to be used during diagnostic and positive airway pressure (PAP) titration polysomnography. An alternative sensor is used if the recommended sensor fails or the signal is inaccurate. The PAP device flow signal is the recommended sensor for the detection of apnea, hypopnea, and respiratory effort related arousals (RERAs) during PAP titration studies. Appropriate filter settings for recording (display) of the nasal pressure signal to facilitate visualization of inspiratory flattening are also specified. The respiratory inductance plethysmography (RIP) signals to be used as alternative sensors for apnea and hypopnea detection are specified. The task force reached consensus on use of the same sensors for adult and pediatric patients except for the following: (1) the end-tidal PCO(2) signal can be used as an alternative sensor for apnea detection in children only, and (2) polyvinylidene fluoride (PVDF) belts can be used to monitor respiratory effort (thoracoabdominal belts) and as an alternative sensor for detection of apnea and hypopnea (PVDFsum) only in adults.The task force recommends the following changes to the 2007 respiratory scoring rules. Apnea in adults is scored when there is a drop in the peak signal excursion by ≥ 90% of pre-event baseline using an oronasal thermal sensor (diagnostic study), PAP device flow (titration study), or an alternative apnea sensor, for ≥ 10 seconds. Hypopnea in adults is scored when the peak signal excursions drop by ≥ 30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative sensor, for ≥ 10 seconds in association with either ≥ 3% arterial oxygen desaturation or an arousal. Scoring a hypopnea as either obstructive or central is now listed as optional, and the recommended scoring rules are presented. In children an apnea is scored when peak signal excursions drop by ≥ 90% of pre-event baseline using an oronasal thermal sensor (diagnostic study), PAP device flow (titration study), or an alternative sensor; and the event meets duration and respiratory effort criteria for an obstructive, mixed, or central apnea. A central apnea is scored in children when the event meets criteria for an apnea, there is an absence of inspiratory effort throughout the event, and at least one of the following is met: (1) the event is ≥ 20 seconds in duration, (2) the event is associated with an arousal or ≥ 3% oxygen desaturation, (3) (infants under 1 year of age only) the event is associated with a decrease in heart rate to less than 50 beats per minute for at least 5 seconds or less than 60 beats per minute for 15 seconds. A hypopnea is scored in children when the peak signal excursions drop is ≥ 30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative sensor, for ≥ the duration of 2 breaths in association with either ≥ 3% oxygen desaturation or an arousal. In children and adults, surrogates of the arterial PCO(2) are the end-tidal PCO(2) or transcutaneous PCO(2) (diagnostic study) or transcutaneous PCO(2) (titration study). For adults, sleep hypoventilation is scored when the arterial PCO(2) (or surrogate) is > 55 mm Hg for ≥ 10 minutes or there is an increase in the arterial PCO(2) (or surrogate) ≥ 10 mm Hg (in comparison to an awake supine value) to a value exceeding 50 mm Hg for ≥ 10 minutes. For pediatric patients hypoventilation is scored when the arterial PCO(2) (or surrogate) is > 50 mm Hg for > 25% of total sleep time. In adults Cheyne-Stokes breathing is scored when both of the following are met: (1) there are episodes of ≥ 3 consecutive central apneas and/or central hypopneas separated by a crescendo and decrescendo change in breathing amplitude with a cycle length of at least 40 seconds (typically 45 to 90 seconds), and (2) there are five or more central apneas and/or central hypopneas per hour associated with the crescendo/decrescendo breathing pattern recorded over a minimum of 2 hours of monitoring.

Circadian blood pressure rhythm and increased body weight in patients with arterial hypertension and obstructive sleep apnoea syndrome

Aim. To assess the specifics of 24-hour blood pressure monitoring (BPM) parameters and their association with body mass index (BMI) in patients with arterial hypertension (AH) and obstructive sleep apnoea (OSA) syndrome. Material and methods. The study included 120 AH patients with BMI under or over 25 kg/m2, who underwent 24-hour BMP and combined monitoring of electrocardiogram (ECG) and breathing. Results. AH patients with OSA syndrome demonstrated increased mean daytime and nighttime levels of systolic and diastolic BP (SBP, DBP) and a 1,5-fold increase in SBP and DBP pressure load indices. Patients with increased BMI had disturbed circadian BP profile, with reduced mean 24-hour difference, more pronounced for DBP (2,4-fold difference), and an increase in the “over-dipper” prevalence (from 13,3 % to 42,1 %). Conclusion. The combination of AH, OSA syndrome, and increased BMI substantially affected 24-hour BPM parameters. Increased BMI was associated with disturbed circadian BP profile and increased levels of mean 24-hour BP and nighttime BP

Current hypopnea scoring criteria underscore pediatric sleep disordered breathing

OBJECTIVE

This is a retrospective study comparing 2007 American Academy of Sleep Medicine (AASM) pediatric scoring criteria and Stanford scoring criteria of pediatric polysomnograms to characterize the impact different scoring systems have upon the diagnosis of sleep disordered breathing in children.

METHODS

The diagnostic and post-treatment nocturnal polysomnograms (PSGs) of children (age 2-18 years) consecutively referred to an academic sleep clinic for evaluation of suspected sleep disordered breathing (SDB) for 1 year were independently analyzed by a single researcher using AASM and Stanford scoring criteria in a blinded fashion.

RESULTS

A total of 209 (83 girls) children with suspected SDB underwent clinical evaluation and diagnostic PSG. Analysis of the diagnostic PSGs using the Stanford and AASM criteria classified 207 and 39 studies as abnormal, respectively. The AASM scoring criteria classified 19% of subjects as having obstructive sleep apnea (OSA) while the Stanford criteria diagnosed 99% of the subjects with OSA who were referred for evaluation of suspected sleep disordered breathing. There was a positive correlation between SDB-related clinical symptoms and anatomic risk factors for SDB. Scatter-plot analyses showed that the AASM apnea hypopnea index (AHI) was not only significantly lower compared to the Stanford AHI but also skewed in distribution. Ninety-nine children were restudied with PSG (9 were initially diagnosed with SDB with AASM criteria, whereas all 99 were diagnosed with SDB with Stanford criteria). All 99 children had been treated and had a post-treatment clinical evaluation and post-treatment PSG during the study period. All 99 children evaluated after treatment showed improvement in clinical presentation, Stanford AHI, and oxygen saturation during sleep.

CONCLUSION

The AASM scoring criteria classified 19% of subjects as having OSA while the Stanford criteria diagnosed 99% of the subjects with OSA who were referred for evaluation of suspected sleep disordered breathing. The primary factor differentiating the AASM and Stanford criteria was the scoring of hypopneas. The AASM definition of hypopnea may be detrimental to the recognition of SDB in children.

Trends in anthropometry and severity of sleep-disordered breathing over two decades of diagnostic sleep studies in an Australian adult sleep laboratory

OBJECTIVE

To document trends in subject demographics, anthropometry and sleep disorder severity over 21 years of diagnostic sleep studies.

DESIGN, PARTICIPANTS AND SETTING

A retrospective observational study of consecutive subjects undergoing initial diagnostic polysomnography for investigation of possible sleep disorders in a university-affiliated tertiary public metropolitan hospital in the Hunter New England region of New South Wales between 1987 and 2007.

MAIN OUTCOME MEASURES

Body weight, body mass index (BMI) and severity of sleep-related breathing disorders (apnoea-hypopnoea index [AHI]).

RESULTS

Between 1987 and 2007, 14 648 new diagnostic sleep studies were performed. The median age of subjects (51 years; interquartile range, 41-61 years) did not change over time and the proportion of women increased from 20% to 39%. Median body weight increased from 89 kg to 99 kg for men (11%) and from 73 kg to 85 kg for women (16%), equating to a yearly increase in median BMI of 0.15 kg/m(2) for men and 0.14 kg/m(2) for women. The proportion of subjects who were morbidly obese (BMI > or = 40) increased from 3% in 1987 to 16% in 2007. Median AHI progressively increased from 1992-1995 to 2004-2007 (from 6.5 events/h to 14.3 events/h; P < 0.001), indicating increasing disease severity. Over the same period, for every unit increase in BMI, AHI increased by 5.5 events/h for men and by 2.8 events/h for women. About 80% of the observed variance in AHI over this period was attributable to variance in BMI.

CONCLUSION

There is a continuing trend towards increasing body weight and BMI in people undergoing diagnostic sleep studies. Our data do not support the hypothesis that increased accessibility to diagnostic services and increased awareness of sleep disorders are resulting in a decline in disease severity. These findings are consistent with the premise that worsening severity in sleep-disordered breathing is primarily attributable to increasing obesity.

The new AASM criteria for scoring hypopneas: impact on the apnea hypopnea index

STUDY OBJECTIVES

To compare apnea-hypopnea indices (AHIs) derived using 3 standard hypopnea definitions published by the American Academy of Sleep Medicine (AASM); and to examine the impact of hypopnea definition differences on the measured prevalence of obstructive sleep apnea (OSA).

DESIGN

Retrospective review of previously scored in-laboratory polysomnography (PSG).

SETTING

Two tertiary-hospital clinical sleep laboratories.

PATIENTS OR PARTICIPANTS

328 consecutive patients investigated for OSA during a 3-month period.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

AHIs were originally calculated using previous AASM hypopnea scoring criteria (AHI(Chicago)), requiring either >50% airflow reduction or a lesser airflow reduction with associated >3% oxygen desaturation or arousal. AHIs using the "recommended" (AHI(Rec)) and the "alternative" (AHI(Alt)) hypopnea definitions of the AASM Manual for Scoring of Sleep and Associated Events were then derived in separate passes of the previously scored data. In this process, hypopneas that did not satisfy the stricter hypopnea definition criteria were removed. For AHI(Rec), hypopneas were required to have > or =30% airflow reduction and > or =4% desaturation; and for AHI(Alt), hypopneas were required to have > or =50% airflow reduction and > or =3% desaturation or arousal. The median AHI(Rec) was approximately 30% of the median AHI(Chicago), whereas the median AHI(Alt), was approximately 60% of the AHI(Chicago), with large, AHI-dependent, patient-specific differences observed. Equivalent cut-points for AHI(Rec) and AHI(Alt), compared to AHI(Chicago) cut-points of 5, 15, and 30/h were established with receiver operator curves (ROC). These cut-points were also approximately 30% of AHI(Chicago) using AHI(Rec) and 60% of AHI(Chicago) using AHI(Alt). Failure to adjust cut-points for the new criteria would result in approximately 40% of patients previously classifled as positive for OSA using AHI(Chicago) being negative using AHI(Rec) and 25% being negative using AHI(Alt).

CONCLUSIONS

This study demonstrates that using different published standard hypopnea definitions leads to marked differences in AHI. These results provide insight to clinicians and researchers in interpreting results obtained using different published standard hypopnea definitions, and they suggest that consideration should be given to revising the current scoring recommendations to include a single standardized hypopnea definition.

Prevalence and severity of sleep apnea in a group of morbidly obese patients

BACKGROUND

Obesity is the most important risk factor for obstructive sleep apnea. It is estimated that 70% of sleep apnea patients are obese. In the morbidly obese, the prevalence may reach 80% in men and 50% in women. The aim of this study was to determine the prevalence and severity of sleep apnea in a group of morbidly obese patients, leading to bariatric surgery.

METHODS

In a cross-sectional study developed in Bahia, northeastern Brazil. 108 patients (78 women and 30 men) from the Obesity Treatment and Surgery Center--"Núcleo de Tratamento e Cirurgia da Obesidade" underwent standard polysomnography. Patients with an apnea-hypopnea index (AHI) > or = 5 events/hour were considered apneic.

RESULTS

Mean +/- SD for age and BMI were 37.1 +/- 10.2 years and 45.2 +/- 5.4 kg/m2, respectively. The calculated AHI ranged widely from 2.5 to 128.9 events/hour. Sleep apnea was detected in 93.6% of the sample, wherein 35.2% had mild, 30.6% moderate and 27.8% severe apnea. Oxyhemoglobin desaturation was directly related to the AHI and was more severe in men.

CONCLUSION

There was a high frequency of sleep apnea in this group of morbidly obese patients, for whom it was very important to request polysomnography, thus enabling therapeutic management and prognostication.

Atomoxetine improves sleepiness and global severity of illness but not the respiratory disturbance index in mild to moderate obstructive sleep apnea with sleepiness

BACKGROUND AND PURPOSE

Norepinephrine reuptake inhibitors such as protriptyline have been shown to improve sleepiness in sleep apnea, with or without improvement in the respiratory disturbance index (RDI). This study was performed to evaluate whether the selective norepinephrine reuptake inhibitor atomoxetine improves sleepiness, the clinical global impression (CGI) of severity of illness, and the RDI in patients with mild to moderate obstructive sleep apnea with excessive sleepiness.

METHODS

Patients aged 18-60 years with RDI (including apneas, hypopneas with desaturations and hypopneas with arousals) >5/h sleep, apnea-hypopnea index (AHI; including apneas, hypopneas with 4% desaturations, but not apneas with arousals) <15/h sleep, and excessive sleepiness (Epworth Sleepiness Scale [ESS]>or=10) received open-label treatment with atomoxetine 40-80 mg HS for 4 weeks, with repeat polysomnography at the end of treatment. Of 20 patients screened, 17 started treatment and 15 completed treatment.

RESULTS

ESS improved from 15.3 to 10.5 and CGI improved from 4.3 to 3.1 (both significant at p<0.01), but there was no significant change in RDI. ESS and CGI improved in a linear fashion across the weeks of treatment. Sleep efficiency and % stage rapid eye movement (REM) sleep were decreased, and % stage 1, awakenings and wake after sleep onset were increased.

CONCLUSIONS

Atomoxetine improved sleepiness and the CGI in patients with mild to moderate obstructive sleep apnea with sleepiness. However, it did not improve the RDI.

Sleep apnea syndrome: improved detection of respiratory events and cortical arousals using oxymetry pulse wave amplitude during polysomnography

Respiratory events (RE) during sleep induce cortical arousals (A) and marked changes in autonomic markers in sleep apnea syndrome (SAS). The aims of the study were double. First, we assessed whether pulse wave amplitude (PWA) added to polysomnography (PSG) could improve RE and A detection; second, we wanted to know whether the quality of detection of these two parameters could be improved using PWA. Respiratory disturbance index (RDI) and A were randomly scored twice by the same observer in 12 male patients with SAS. The first scoring was done using conventional PSG signals, the second scoring adding PWA to PSG. We also measured interobserver agreement by randomly selecting and reading 100 PSG sequences of 5 min with and without PWA by two observers. Adding PWA to PSG parameters allowed to detect significantly more RDI (53.9 +/- 21.6 h(-1) versus 48.3 +/- 22.3 h(-1), p < 0.001) and more A (68.0 +/- 14.4 versus 59.4 +/- 16.5, p < 0.001). Moreover, after using PWA, there was no significant disagreement between two observers for detecting RE, showing better quality of RE detection. PWA is a simple and cheap parameter that improves the diagnostic value of conventional PSG in sleep apnea syndrome by better detecting respiratory events and A.

Hypopnea in pediatric patients with obesity hypertension

Obesity is associated with the development of hypertension but it is still not clear why hypertension is not observed in all obese patients. Obesity is a risk factor for the development of obstructive sleep apnea syndrome (OSAS) in children. OSAS has been linked to the development of hypertension in adults and children. The purpose of this study was to test the hypothesis that OSAS is one of the reasons that some obese children are hypertensive and some are not. The overnight polysomnography records of 90 patients (aged 4.2-18.8 years) were reviewed. BMI(score) [body mass index (BMI)/95th percentile BMI for age, sex, and race] was used to express the degree of obesity. The severity of systolic hypertension and diastolic hypertension were expressed as SBP(score) (systolic BP/the 95th percentile systolic BP for age, sex, and height) and DBP(score) (diastolic BP/the 95th percentile diastolic BP for age, sex, and height), respectively. OSAS was defined as more than one episodes of apnea per hour (AI) or an O(2) saturation associated with obstructive apnea of less than 90%. There were 56 obese patients; 42 were hypertensive and 40 patients were diagnosed with OSAS. The incidence of hypertension (68% vs. 30%) and obesity (75% vs. 52%) was higher in OSAS patients than those without OSAS. Compared with the non-obese patients, obese patients had a higher incidence of hypertension or OSAS, a higher BMI(score), SBP(score), DBP(score), AI, hypopnea index (HI), and apnea-hypopnea index (AHI). In obese patients, both SBP(score) and DBP(score) correlated positively with BMI(score), arousal index, and HI. DBP(score) also correlated positively with AHI. Multiple regression analysis showed that HI and BMI(score) were significant independent predictors of SBP(score) or DBP(score). Obese and hypertensive patients had a higher HI, AHI, and incidence of OSAS (64% vs. 29%) than the obese and normotensive patients. In conclusion, HI had a significant correlation with the degree of hypertension in obese patients, which could not be attributed to the degree of obesity. These findings are consistent with the hypothesis that OSAS is one of the reasons why some obese children are hypertensive and some are not.

Comparison of Nasal Prong Pressure and Thermistor Measurements for Detecting Respiratory Events during Sleep

INTRODUCTION AND OBJECTIVES

Thermistor (TH) measurements have been traditionally used to determine airflow during polysomnographic studies (PSG). However, low accuracy in detecting hypopneas is a major drawback. Nasal prong pressure (NPP) measurements are becoming increasingly popular for quantifying respiratory events during sleep. We prospectively compared NPP and TH measurements with respect to their ability to detect respiratory events during routine PSG.

METHODS

Forty consecutive patients (26 male, 14 female) with clinically suspected sleep-disordered breathing (SDB) underwent routine diagnostic PSG. Airflow was measured using NPP and TH devices simultaneously. PSG was scored manually according to R and K criteria. Respiratory events were scored in two passes. During the first pass, the TH signal was disabled and the NPP signal was scored. During the second pass, the NPP signal was disabled and the TH signal was scored. Scorers for one method were blinded from the results of the other method. To assess respiratory events, we used the respiratory arousal index (RAI), which was defined as the number of apneas and/or hypopneas followed by an arousal per hour of sleep, as detected by TH (RAI-TH) or NPP (RAI- NPP). Agreement analysis of the results obtained using the two different techniques was performed using the methodology of Bland-Altman.

RESULTS

Twenty-six patients had obstructive sleep apnea, 10 had respiratory effort-related arousals and 4 had habitual snoring. The failure time of the flow signal on the raw data was not different between the two methods (NPP: 6 +/- 13 min, TH: 4 +/- 7 min). The Bland-Altman analysis of RAIs demonstrated that more events were nearly always detected using NPP compared to TH devices (44.4 +/- 37 vs. 35.4 +/- 31, p < 0.001). No difference in the index of central apneas between the two methods could be detected. Sleep position had no effect on either measurement method.

CONCLUSIONS

NPP measurements are superior to TH measurements for detecting obstructive respiratory events during sleep. Measurement of NPP is a simple, practical, sensitive and reliable method for detecting the whole spectrum of SDB. We recommend incorporating nasal prongs in routine polysomnographic monitoring.

Monitoring respiration during sleep

The sleep-related breathing disorders have been categorized in various ways. The most basic schema divides them into obstructive or central apneic events. An American Academy of Sleep Medicine (AASM) Task Force Report published in 1999 defined four separate syndromes associated with abnormal respiratory events during sleep among adults, namely, obstructive sleep apnea-hypopnea syndrome (OSAHS), central sleep apnea-hypopnea syndrome, Cheyne-Stokes breathing syndrome, and sleep hypoventilation syndrome. In this classification, the upper airway resistance syndrome was not regarded as a distinct syndrome; instead, respiratory event-related arousals (RERAs) were considered part of the syndrome of OSAHS.

Apneas, hypopneas, and respiratory effort-related arousals: moving closer to a standard

The spectrum of sleep disordered breathing ranges from intermittent snoring to the obesity hypoventilation syndrome with the obstructive sleep apnea/hypopnea syndrome fitting somewhere in between. Recently, improved definitions and monitoring techniques are allowing for clearer differentiation of the syndromes within this spectrum. These new standards have also produced better understanding of the prognosis and treatment options for patients fitting into different points within this spectrum. Furthermore, effective communication of current definitions and techniques has resulted in improved reimbursement for the treatments of patients with sleep disordered breathing.

The Victorian CPAP program: is there a need for additional education and support?

BACKGROUND

The Victorian Continuous Positive Airways Pressure (CPAP) Program provides CPAP services to financially disadvantaged individuals with moderate to severe sleep apnoea.

AIMS

To evaluate health outcomes in patients referred to the pilot program in order to: (i) assess the magnitude of health benefit from treatment in this highly selected population and (ii) identify patient characteristics or factors related to service provision that may influence outcome.

METHODS

We adopted a simple before-after research design. Patients who were referred to the program were recruited from five sleep centres. Questionnaires were administered at baseline and 1 and 3 months after commencing CPAP. Generic and disease-specific quality of life were assessed using the MOS 36-Item Short-form Health Survey and the Sleep Apnoea Quality-of-life Index, respectively. Subjective daytime sleepiness was measured using the Epworth Sleepiness Scale and the Sleep-Wake Activity Inventory.

RESULTS

Of the 68 subjects enrolled in the study, 59 were available for follow up. There were significant improvements in daytime sleepiness (P < 0.0005). Treatment-related symptoms had a negative impact on overall disease-specific quality of life, however there were significant improvements in all other domains of disease-specific quality of life (P < 0.0005). Improvements in generic quality of life were small but statistically significant (P < 0.05). Hospital, disease severity, baseline sleepiness, gender and CPAP-machine type were not predictors of outcome (P > 0.05).

CONCLUSION

This review of the Victorian CPAP Program identified significant improvements in subjective daytime sleepiness and quality of life, despite the negative impact of treatment-related symptoms. Future research should explore whether services can be modified to help reduce the impact of treatment-related side-effects.

Measurement variability in sleep disorders medicine: the Victorian experience

BACKGROUND

Surveys of laboratories in North America have documented significant diversity in the working definitions used for reporting respiratory events in sleep studies.

AIM

To assess sources of variability in the measurement of sleep-disordered breathing (as defined by the Apnoea-Hypopnoea Index) between sleep laboratories in Victoria, Australia.

METHODS

A self-complete written questionnaire was constructed following literature review and interviews with staff at three separate sleep laboratories. The survey was sent to all laboratories listed in Victoria by the Australasian Sleep Association. The first part of the survey related to the type of equipment used to record sleep and other variables during overnight polysomnography and the second part related to the definitions and methods used to report results.

RESULTS

Seventeen out of 18 laboratories returned the surveys. There were variations identified in the types of sensors used to measure particular signals. There were also inconsistencies identified in the criteria used to score arousals, apnoeas and hypopnoeas by different laboratories. The variability was greatest for hypopnoea definitions.

CONCLUSIONS

There is considerable variation in the methods used to measure and define sleep-disordered breathing between sleep laboratories in Victoria. The extent to which these variations influence the comparability of reported results between laboratories requires further evaluation. The survey findings may assist the process of developing and implementing local guidelines for the performance and reporting of polysomnography.