Central Hypopneas Research Articles

P-SP003. Idiopathic central sleep apnea with periodicity presenting as cheyne-stokes breathing

Introduction . Cheyne-Stokes breathing (CSB) is described by a cyclic variation in breathing with periods of central apneas or hypopneas alternating with periods of hyperpneas in a gradual waxing and waning manner. We describe this rare case of idiopathic central sleep apnea coming in a periodic fashion presenting as CSB pattern without specific causes. Results . A 72-year-old male (body mass index: 21.9 kg/m 2 ) with the complaints of excessive daytime sleepiness and fatigue for about 2 years. On detailed sleep history patient denied snoring, cataplexy, hypnogogic hallucination, sleep paralysis and sleep attack. No neurological deficit was seen in clinical evaluation. ENT evaluation was normal. Cardiac evaluation showed artrial fibrillation with no cardiac failure. An overnight Polysomnography (PSG) test showed total sleep time of 443 minutes, sleep latency of 19.0 min, and sleep efficiency of 70.0%. Sleep architecture for stage 1 sleep was 31.7%, stage 2 sleep was 52.4%, slow wave sleep was 12.9%, REM sleep was 3.1%. Total arousal index was 21.8/hr. Mean SaO2 was 96.4%, the lowest SaO2 was 82.8%, and SaO2 below 90% was 0.1%. Snoring was not observed and periodic limb movement index was 8.8/hr. PSG also showed cyclic fluctuation in breathing with periods of central apneas; alternating with periods of hyperpneas in a gradual waxing and waning fashion; but cardiac evaluation and magnetic resonance imaging of the brain could not find any cause of this sleep-disordered breathing. Conclusion . The pathogenesis and etiology of CSA is still vague. We think that further studies and follow up will be required to determine whether idiopathic central sleep apnea presenting as CSB pattern is the initial indication of certain diseases. So we concluded that this case was an idiopathic central sleep apnea with periodicity; presenting as CSB pattern.

A comparison of 2 visual methods for classifying obstructive vs central hypopneas.

Rules for classifying apneas as obstructive, central, or mixed are well established. Although hypopneas are given equal weight when calculating the apnea-hypopnea index, classification is not standardized. Visual methods for classifying hypopneas have been proposed by the American Academy of Sleep Medicine and by Randerath et al (Sleep. 2013;36[3]:363-368) but never compared. We evaluated the clinical suitability of the 2 visual methods for classifying hypopneas as central or obstructive. Fifty hypopnea-containing polysomnographic segments were selected from patients with clear obstructive or clear central physiology to serve as standard obstructive or central hypopneas. These 100 hypopnea-containing polysomnographic segments were deidentified, randomized, and scored by 2 groups. We assigned 1 group to use the American Academy of Sleep Medicine criteria and the other the Randerath algorithm. After a washout period, re-randomized hypopnea-containing polysomnographic segments were scored using the alternative method. We determined the accuracy (agreement with standard), interrater (Fleiss's κ), and intrarater agreement (Cohen's κ) for obtained scores. Accuracy of the 2 methods was similar: 67% vs 69.3% for Randerath et al and the American Academy of Sleep Medicine, respectively. Cohen's κ was 0.01-0.75, showing that some raters scored similarly using the 2 methods, while others scored them markedly differently. Fleiss's κ for the American Academy of Sleep Medicine algorithm was 0.32 (95% confidence interval, 0.29-0.36) and for the Randerath algorithm was 0.27 (95% confidence interval, 0.23-0.30). More work is needed to discover a noninvasive way to accurately characterize hypopneas. Studies like ours may lay the foundation for discovering the full spectrum of physiologic consequences of obstructive sleep apnea and central sleep apnea.

Clinical Study of Autonomic Dysfunction in Patients With Anti-NMDA Receptor Encephalitis.

Objectives: Autonomic dysfunction is a common symptom of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis; however, it has been poorly researched. The purpose of this study was to compare the clinical features, tumor occurrence, intensive care unit (ICU) admission, mechanical ventilation, imaging assessment, cerebrospinal fluid examination, disease severity, and immunotherapy in patients with anti-NMDAR encephalitis with or without autonomic dysfunction.Methods: A retrospective study of anti-NMDAR encephalitis patients diagnosed between January 2016 and April 2020 was performed at the First Affiliated Hospital of Zhengzhou University. Patients were divided into two groups according to whether they had autonomic dysfunction, and their clinical features, treatment, and prognosis were compared.Results: A total of 119 patients with anti-NMDAR encephalitis were included in this study. Seventy-three patients (61.3%) had autonomic dysfunction, while the remaining 46 (38.7%) did not. Sinus tachycardia (69.9%) was the autonomic dysfunction with the highest incidence, while the incidences of symptoms including constipation, central hypopnea, and others gradually decreased. Compared to the group without autonomic dysfunction, the prevalence of the main clinical symptoms such as epileptic seizure (P = 0.003), involuntary movement (P = 0.028), and decreased consciousness (P < 0.001) were higher in the group with autonomic dysfunction, which also more frequently presented with complications such as pulmonary infection (P < 0.001) and abnormal liver function (P = 0.001). Moreover, the rates of ICU admission (P < 0.001) and mechanical ventilation (P = 0.001), as well as the modified Rankin scale (mRS) scores at admission (P < 0.001), maximum mRS scores during the course of disease (P < 0.001), and mRS scores at discharge (P < 0.001) were higher in the patients with autonomic dysfunction than in those without. The number of patients in the autonomic dysfunction group who underwent ≥2 immunotherapies was also higher than that in the group without autonomic dysfunction (P < 0.001).Conclusion: Sinus tachycardia is the most common type of autonomic dysfunction in anti-NMDAR encephalitis. Compared to patients without autonomic dysfunction, those with autonomic dysfunction had a higher incidence of epilepsy, involuntary movements, decreased consciousness, pulmonary infections, abnormal liver function, ICU admissions, and mechanical ventilation; moreover, the severity of the disease was greater, and their prognosis worse. Therefore, such patients require intensive immunotherapy.

Portable Sleep Apnea Syndrome Screening and Event Detection Using Long Short-Term Memory Recurrent Neural Network.

Obstructive sleep apnea/hypopnea syndrome (OSAHS) is characterized by repeated airflow partial reduction or complete cessation due to upper airway collapse during sleep. OSAHS can induce frequent awake and intermittent hypoxia that is associated with hypertension and cardiovascular events. Full-channel Polysomnography (PSG) is the gold standard for diagnosing OSAHS; however, this PSG evaluation process is unsuitable for home screening. To solve this problem, a measuring module integrating abdominal and thoracic triaxial accelerometers, a pulsed oximeter (SpO2) and an electrocardiogram sensor was devised in this study. Moreover, a long short-term memory recurrent neural network model is proposed to classify four types of sleep breathing patterns, namely obstructive sleep apnea (OSA), central sleep apnea (CSA), hypopnea (HYP) events and normal breathing (NOR). The proposed algorithm not only reports the apnea-hypopnea index (AHI) through the acquired overnight signals but also identifies the occurrences of OSA, CSA, HYP and NOR, which assists in OSAHS diagnosis. In the clinical experiment with 115 participants, the performances of the proposed system and algorithm were compared with those of traditional expert interpretation based on PSG signals. The accuracy of AHI severity group classification was 89.3%, and the AHI difference for PSG expert interpretation was . The overall accuracy of detecting abnormal OSA, CSA and HYP events was 92.3%.

Detection and Classification of Sleep Apnea and Hypopnea Using PPG and SpO 2 Signals.

In this work, a detection and classification method for sleep apnea and hypopnea, using photopletysmography (PPG) and peripheral oxygen saturation (SpO 2) signals, is proposed. The detector consists of two parts: one that detects reductions in amplitude fluctuation of PPG (DAP)and one that detects oxygen desaturations. To further differentiate among sleep disordered breathing events (SDBE), the pulse rate variability (PRV) was extracted from the PPG signal, and then used to extract features that enhance the sympatho-vagal arousals during apneas and hypopneas. A classification was performed to discriminate between central and obstructive events, apneas and hypopneas. The algorithms were tested on 96 overnight signals recorded at the UZ Leuven hospital, annotated by clinical experts, and from patients without any kind of co-morbidity. An accuracy of 75.1% for the detection of apneas and hypopneas, in one-minute segments,was reached. The classification of the detected events showed 92.6% accuracy in separating central from obstructive apnea, 83.7% for central apnea and central hypopnea and 82.7% for obstructive apnea and obstructive hypopnea. The low implementation cost showed a potential for the proposed method of being used as screening device, in ambulatory scenarios.

Amelioration of sleep-disordered breathing with supplemental oxygen in older adults.

Elderly adults demonstrate increased propensity for breathing instability during sleep compared with younger adults, and this may contribute to increased prevalence of sleep-disordered breathing (SDB) in this population. Hence, in older adults with SDB, we examined whether addition of supplemental oxygen (O2) will stabilize breathing during sleep and alleviate SDB. We hypothesized that exposure to supplemental O2 during non-rapid eye movement (NREM) sleep will stabilize breathing and will alleviate SDB by reducing ventilatory chemoresponsiveness and by widening the carbon dioxide (CO2) reserve. We studied 10 older adults with mild-to-moderate SDB who were randomized to undergo noninvasive bilevel mechanical ventilation with exposure to room air or supplemental O2 (Oxy) to determine the CO2 reserve, apneic threshold (AT), and controller and plant gains. Supplemental O2 was introduced during sleep to achieve a steady-state O2 saturation ≥95% and fraction of inspired O2 at 40%-50%. The CO2 reserve increased significantly during Oxy versus room air (-4.2 ± 0.5 mmHg vs. -3.2 ± 0.5 mmHg, P = 0.03). Compared with room air, Oxy was associated with a significant decline in the controller gain (1.9 ± 0.4 L/min/mmHg vs. 2.5 ± 0.5 L/min/mmHg, P = 0.04), with reductions in the apnea-hypopnea index (11.8 ± 2.0/h vs. 24.4 ± 5.6/h, P = 0.006) and central apnea-hypopnea index (1.7 ± 0.6/h vs. 6.9 ± 3.9/h, P = 0.03). The AT and plant gain were unchanged. Thus, a reduced slope of CO2 response resulted in an increased CO2 reserve. In conclusion, supplemental O2 reduced SDB in older adults during NREM sleep via reduction in chemoresponsiveness and central respiratory events.NEW & NOTEWORTHY This study demonstrates for the first time in elderly adults without heart disease that intervention with supplemental oxygen in the clinical range will ameliorate central apneas and hypopneas by decreasing the propensity to central apnea through decreased chemoreflex sensitivity, even in the absence of a reduction in the plant gain. Thus, the study provides physiological evidence for use of supplemental oxygen as therapy for mild-to-moderate SDB in this vulnerable population.

The influence of opioids and nonopioid central nervous system active medications on central sleep apnea: a case-control study.

Opioids are known to contribute to central sleep apnea (CSA), but the influence of nonopioid central nervous system active medications (CNSAMs) on CSA remains unclear. In light of the hypothesized impact of nonopioid CNSAMs on respiration, we examined the relationships between the use of opioids only, nonopioid CNSAMs alone, and their combination with CSA. Among all adults who underwent polysomnography testing at the University of Michigan's sleep laboratory between 2013 and 2018 (n = 10,606), we identified 212 CSA cases and randomly selected 300 controls. Participants were classified into four groups based on their medication use: opioids alone, nonopioid CNSAMs only, their combination, and a reference group, including those who did not use any of these medications. We defined CSA as a binary outcome and as a continuous variable using central apnea index data. Logistic and linear regression were used to examine associations between medication use, CSA diagnosis, and central apnea index. Study participants included 58% men, and mean age was 50 (± 14 standard deviation years. Nearly half of the study participants did not use opioids or nonopioid CNSAMs, 6% used opioids alone, 27% nonopioid CNSAMs alone, and 16% used a combination of these medications. In adjusted analyses, opioids-only users had a nearly twofold increase in CSA odds, whereas those who used a combination of opioids and nonopioid CNSAMs had fivefold higher odds of CSA relative to the reference group. In contrast, the use of nonopioid CNSAMs alone had protective associations with CSA. This report showed increased odds of CSA, particularly among patients with sleep complaints who were prescribed opioids in combination with nonopioid CNSAMs compared with those who did not use any of these medications.

Central sleep apnea is uncommon after stroke

Objective/backgroundStroke is often considered a risk factor for central sleep apnea (CSA). The goal of this study was to determine the prevalence and clinical correlates of CSA in patients with ischemic stroke. Patients/methodsIn this analysis, 1346 participants in the Brain Attack Surveillance in Corpus Christi (BASIC) project underwent a home sleep apnea test shortly after ischemic stroke. Respiratory events during sleep were classified as central apneas, obstructive apneas, or hypopneas. Central apnea index (CAI) was defined as number of central apneas divided by recording time. CSA was defined as CAI ≥5/hour with at least 50% of all scored respiratory events classified as central apneas. Demographics and co-morbidities were ascertained from the medical record. ResultsMedian CAI was 0/hour. Nineteen participants (1.4%) met criteria for CSA. Participants with CSA were more likely to be male, and had lower prevalence of obesity than participants without CSA. There was no association between CSA and other co-morbidities. ConclusionsCSA was uncommon in this large cohort of patients with recent ischemic stroke.

0698 A Comparison Of Two Visual Hypopnea Classification Methods

Abstract Introduction The rules for classifying apneas as either obstructive or central using usual polysomnography (PSG) channels are well established, but classification of hypopneas is less straightforward without special sensors. Visual scoring methods have been proposed by the American Academy of Sleep Medicine (AASM) and by Randerath, et al. These two scoring methods have never been compared. We evaluated these two scoring methods for clinical use. Methods We selected 50 hypopnea segments from patient’s PSGs with very clear obstructive physiology (average total AHI 48.6, central AI 0), assumed to be obstructive hypopneas, and from patient’s PSGs with very clear central physiologies (average total AHI 34.3, obstructive AI 0.3), assumed to be central hypopneas. These 100 hypopnea-containing PSG segments (HCPS) were deidentified, placed in randomized order, and sent to two groups of 6 PSG scorers (2 RPSGTs, 2 sleep medicine fellows, 2 sleep medicine specialists). One group scored using the AASM criteria and the other used the Randerath algorithm. After a washout period, re-randomized HCPS were sent to be scored using the alternative method. We used Fleiss’ kappa to determine inter-rater reliability—i.e., how consistently multiple scorers came to the same conclusion about a given hypopnea segment using each method, and accuracy—how often the scorers rated the HCPS in a manner consistent with the assumed physiology. We also recorded the time it took to score. Results Overall accuracy of both methods was 68%. Among 12 scorers, Fleiss’ Kappa coefficient was 0.32 and 0.27 for the AASM and Randerath scoring methods, respectively. Average scoring time (24.3 minutes for AASM and 26.2 minutes for Randerath) was similar (p=0.79). Conclusion Inter-rater agreement was only fair using these methods, and accuracy was only 68%. More work is needed to discover a convenient, non-invasive way to reproducibly and accurately characterize hypopneas. Support This project does not have any funding support.

0451 Fully Automatic Detection of Sleep Disordered Breathing Events

Abstract Introduction Evaluation of sleep apnea involves manual annotation of Polysomnography (PSG) file, a time-consuming process subject to interscorer variations. The DOSED algorithm has been shown to be helpful in detecting Central Sleep Apnea (CSA), Obstructive Sleep Apnea (OSA), and Hypopnea when merged into a single event type. This work uses a modified version of DOSED capable of detecting each event type separately. Methods The network consists of 3 blocks of 1D convolutional layers followed by 6 blocks of 2D convolutional layers. The network has 2 classification layers, one determines the probability of each class, and the other determines the start and duration time of the event with the highest probability. Four channels from nasal and mouth airflow and position of abdomen and thorax are used as input to the model. The model was trained using 2800 PSG from 4 different cohorts (MESA, MROS, SSC, WSC) and tested on 70 PSG, which have been scored by six technicians (Stanford, U Penn, St Louis). Results On an event by event basis, model F1-scores versus a weighted consensus score based on 6 technicians were 0.60 for OSA, 0.43 for CSA, and 0.34 for Hypopnea. Average F1-scores for the 6 technicians were 0.48 (std 0.04) for OSA, 0.29 (std 0.145) for CSA, and 0.54 (std 0.183) for Hypopnea, indicating that the model functions better on an event-by-event basis than an average technician. Correlations between indices/hr for central apnea, obstructive apnea, and hypopnea indicate excellent correlations for apneas, but poor correlation for hypopnea. We are now adding the snoring channel to explore if predictions can be improved. Conclusion The result shows that deep learning-based models can detect respiratory events with an accuracy similar to technicians. The poor agreement between technicians from different universities indicates that we need better definitions of hypopnea. Support

1266 Primary Central apnea and loss of muscle atonia during REM

Abstract Introduction Central sleep apnea (CSA) syndrome is defined when five or more central apneas and/or hypopneas are present per hour of sleep, more than 50% of all respiratory events. CSA usually occur during NREM stage and rarely during REM. CSA is important to recognize because of complications ranging from frequent nighttime awakenings,sleepiness to adverse cardiovascular outcomes. We present a 40 year old female patient with rare CSA during REM sleep and dream enactment. Report of Case 40yo African American female with history of loud snoring, witnessed sleep apnea, and daytime fatigue. She reported nightmares, sleep talking, and acting out her dreams without injury. Epworth sleepiness score was 5 /24. Her past medical history is significant for depression and anxiety. She has no history of head trauma, no neurologic or cardiovascular disorders. Her medications include fluoxetine and,quetiapine. She denied substance use, narcotic use, or alcohol use. Her level 1 sleep study showed predominantly REM-associated central sleep apneas which is rare. She also was observed to have loss of REM sleep muscle atonia suggestive of REM Behavior disorder. Her sleep architecture was atypical with decreased N3 sleep stage. REM sleep duration was adequate. She was noted to have loss of REM muscle atonia based on AASM guidelins elevated chin EMG, excessive transient muscle activity, and witnessed movement during REM stage via video monitoring. During the study, she had an apnea/hypopnea index (AHI) of 13.1 per hour of sleep, Central apneas were predominantly noted during REM stage, 10 per hour, comprised of 50% of her respiratory events. The minimum SpO2 value with CSA was 94%. She had normal sinus rhythm. Her sleep was fragmented. A total arousals were 28.4/hour,and 7.9/hour were respiratory arousals, and the rest were spontaneous arousals. An echocardiogram showed normal left ventricular ejection fraction of 55 to 60 %. Her room air arterial blood gas was normal with PaC02 of 37 mmHg. MRI of the brain/brainstem was ordered given her atypical REM sleep. She had no acute intracranial abnormalities. There is a non specific finding of a low lying cerebellar tonsils without evidence of Chiari I malformation. Conclusion Our patient has rare idiopathic central apnea in REM stage and is third case reported. She also has loss of muscle atonia during REM with dream enactment which is also rare in her age group. Injury precaution advised.

Effect of mild obstructive sleep apnea in mountaineers during the climb to Mount Aconcagua.

Objectiveto compare mountaineers with and without asymptomatic sleep apnea (OSA) before the ascent and to study high altitude-related sleep disorders, its interaction with metabolic, neuroendocrine and immunological components.Material and MethodsDuring an expedition to Mount Aconcagua, researchers assessed the respiratory polygraphy (RP), clinical condition and inflammatory parameters, and rhythm of cortisol secretion in mountaineers sleeping at different altitude camps.Results8 athletes (4 women), 36 years old (25-51) participated. Baseline and final BMI were; 23.6 (20.9-28.7) and 22.77 (20.9-27.7), respectively: p<0.01. 40 valid RP recordings were analyzed. At 746 m.a.s.l. (baseline), only 2 mountaineers presented mild asymptomatic OSA. The OSA group presented baseline apnea-hypopnea index (AHI) values between 5-15 events per hour, which evidence a mild respiratory sleep disorder with AHI increased by altitude depending of central apneas and hypopneas (p<0.05) as high altitude periodic breathing pattern but no increase in obstructive apneas (p<0.01). The circadian rhythm of cortisol was maintained in all cases in which they had not received treatment with dexamethasone and their values increased with the altitude reached. Increased systolic blood pressure was observed in the OSA group.ConclusionIn a context of hypobaric hypoxia, individuals with pre-existing asymptomatic OSA are prone to experiencing lower oxygen saturations and clinical deterioration.

Respiratory Mandibular Movement Signals Reliably Identify Obstructive Hypopnea Events During Sleep.

Context: Accurate discrimination between obstructive and central hypopneas requires quantitative assessments of respiratory effort by esophageal pressure (OeP) measurements, which preclude widespread implementation in sleep medicine practice. Mandibular Movement (MM) signals are closely associated with diaphragmatic effort during sleep.Objective: We aimed at reliably detecting obstructive off central hypopneas events using MM statistical characteristics.Methods: A bio-signal learning approach was implemented whereby raw MM fragments corresponding to normal breathing (NPB; n = 501), central (n = 263), and obstructive hypopneas (n = 1861) were collected from 28 consecutive patients (mean age = 54 years, mean AHI = 34.7 n/h) undergoing in-lab polysomnography (PSG) coupled with a MM magnetometer, and OeP recordings. Twenty three input features were extracted from raw data fragments to explore distinctive changes in MM signals. A Random Forest model was built upon those input features to classify the central and obstructive hypopnea events. External validation and interpretive analysis were performed to evaluate the model's performance and the contribution of each feature to the model's output.Results: Obstructive hypopneas were characterized by a longer duration (21.9 vs. 17.8 s, p < 10−6), more extreme low values (p < 10−6), a more negative trend reflecting mouth opening amplitude, wider variation, and the asymmetrical distribution of MM amplitude. External validation showed a reliable performance of the MM features-based classification rule (Kappa coefficient = 0.879 and a balanced accuracy of 0.872). The interpretive analysis revealed that event duration, lower percentiles, central tendency, and the trend of MM amplitude were the most important determinants of events.Conclusions: MM signals can be used as surrogate markers of OeP to differentiate obstructive from central hypopneas during sleep.

Effectiveness of Sleep Apnea Detection Based on One vs. Two Symmetrical EEG Channels.

Typically, two symmetrical EEG channels are recorded during polysomnography (PSG). As a rule, only the recommended channel is used for sleep stage scoring or sleep apnea detection, and the other for backup. Concurrently, there are many works demonstrating the asymmetry in brain activity. The aim of this work was to compare the accuracy of sleep apnea detection with the use of features obtained from one (C3-A2 or C4-A1) versus these two symmetrical EEG channels. To this end, the relevant data from the PhysioBank database (25 whole-night PSGs) were used. The same methodology of feature extraction and selection was applied for one and combined EEG channels. Automated classification was performed using the k-nearest neighbors algorithm (kNN) with k = 12 and cityblock metric for the three classes of EEG epochs, representing normal breathing, obstructive apnea and hypopnea, and central apnea and hypopnea. The accuracy of kNN-based classification was 63.8 %, 64.3 % and 70.3 % for C3-A2, C4-A1 and both EEG channels, respectively. The statistical tests have indicated that the accuracy of classification based on two combined symmetrical EEG channels is significantly higher compared to the single-channel cases.

Periodic breathing in healthy young adults in normobaric hypoxia equivalent to 3500\xa0m, 4500\xa0m, and 5500\xa0m altitude

PurposeThe occurrence of periodic breathing (PB) at high altitude during sleep and the quality of sleep are individually different and influenced by multiple factors including sex. Although poor sleep quality at high altitude might not be directly linked to oxygen desaturations, the PB upsurge at high altitude leads to significant oscillations in oxygen saturation.MethodsThirty-three students were recruited. Participants were randomly assigned to three groups (A, B, C) sleeping one full night in a dormitory with normobaric hypoxia at a FIO2 of 14.29% (A), a FIO2 of 12.47% (B), or a FIO2 of 10.82% (C). Full polysomnography was performed in each participant.ResultsMean total sleeping time decreased significantly with increasing hypoxia (p < 0.001). Respiratory events changed from central hypopneas to central apneas (CA) with increasing hypoxia: CA = 17.8%, 50.0%, 92.2% of AHI (37.96 events per hour (n/h), 68.55 n/h, 93.44 n/h). AHI (p = 0.014) and time duration of respiratory events (p = 0.003) were significantly different between sexes, both greater in men. REM sleep was reduced.ConclusionsMen tend to be more prone to PB in normobaric hypoxia. Further research should implicate a longer acclimatization period around simulated 4500 m in order to find out if the exponential increase in PB between 4500 m and 5500 m could be shifted to lower hypoxic levels, i.e., higher altitudes.

Complex Sleep Apnea

The term complex sleep apnea syndrome (Comp-SAS) refers to a specific variant of respiratory impairment during sleep characterized by the appearance or significant increases in the number of episodes of central apnea and hypopnea after starting CPAP therapy for obstructive sleep apnea syndrome (OSAS). The mechanisms producing Comp-SAS are not fully understood. It is possible that respiration with positive pressure and elimination of pharyngeal obstruction in some patients lead to increases in pulmonary ventilation and decreases in PaCO2 to below the individual threshold required for stimulating respiration. The prevalence of Comp-SAS is 5–20% of patients with OSAS receiving CPAP therapy. Significant clinical predictors for Comp-SAS have not been established, though this respiratory disorder is known to occur more frequently in male patients, older patients, those with severe OSAS, and those with cardiovascular diseases such as ischemic heart diseases, atrial fibrillation, or chronic heart failure (CHF). In most cases, Comp-SAS settles spontaneously after 1–2 months of regular CPAP therapy. If positive pressure treatment has no effect, other contemporary treatment methods can be used, such as adaptive servo ventilation or BPAP treatment with controlled respiratory frequency, though these are contraindicated in systolic heart failure. The question of whether treatment of patients with Comp-SAS is obligatory when the course of illness is straightforward and symptom-free remains open.

National survey: current prevalence and characteristics of home mechanical ventilation in Hungary

BackgroundHome mechanical ventilation is an established treatment for chronic respiratory failure resulting in improved survival and quality of life. Technological advancement, evolving health care reimbursement systems and newly implemented national guidelines result in increased utilization worldwide. Prevalence shows great geographical variations and data on East-Central European practice has been scarce to date. The aim of the current study was to evaluate prevalence and characteristics of home mechanical ventilation in Hungary.MethodsWe conducted a nationwide study using an online survey focusing on patients receiving ventilatory support at home. The survey focused on characterization of the site (affiliation, type), experience with home mechanical ventilation, number of patients treated, indication for home mechanical ventilation (disease type), description of home mechanical ventilation (invasive/noninvasive, ventilation hours, duration of ventilation) and description of the care provided (type of follow up visits, hospitalization need, reimbursement).ResultsOur survey uncovered a total of 384 patients amounting to a prevalence of 3.9/100,000 in Hungary. 10.4% of patients received invasive, while 89.6% received noninvasive ventilation. The most frequent diagnosis was central hypopnea syndromes (60%), while pulmonary (20%), neuromuscular (11%) and chest wall disorders (7%) were less frequent indications. Daily ventilation need was less than 8 h in 74.2%, between 8 and 16 h in 15.4% and more than 16 h in 10.4% of patients reported. When comparing sites with a limited (< 50 patients) versus substantial (> 50 patients) case number, we found the former had significantly higher ratio of neuromuscular conditions, were more likely to ventilate invasively, with more than 16 h/day ventilation need and were more likely to provide home visits and readmit patients (p < 0,001).ConclusionsOur results show a reasonable current estimate and characterization of home mechanical ventilation practice in Hungary. Although a growing practice can be assumed, current prevalence is still markedly reduced compared to international data reported, the duality of current data hinting to a possible gap in diagnosis and care for more dependent patients. This points to the importance of establishing home mechanical ventilation centers, where increased experience will enable state of the art care to more dependent patients as well, increasing overall prevalence.

Cyclic alternating pattern in infants with congenital hypothyroidism

Congenital hypothyroidism is defined as thyroid hormone deficiency present at birth which is crucial for brain development. Recently, the cyclic alternating pattern, a rhythm present in electroencephalography recordings in non-Rapid eye movement sleep, has been related to brain development and cognition in different pediatric conditions. Therefore, we evaluated the cyclic alternating pattern rate in infants with congenital hypothyroidism, thyroxine supplementation, and healthy controls. The parameters of the cyclic alternating pattern were evaluated in 19 healthy infants (10 female, mean age 25.5 ± 15.5 months) and 21 infants diagnosed with congenital hypothyroidism (19 female, mean age 24.3 ± 19.0 months). We considered the transient electro-cortical activations (phase A of the cycle) in non-Rapid eye movement sleep and the subdivisions of the A phase in: A1, A2 and A3, based on their frequency content. All subjects were subjected to polysomnography recording in a standard laboratory setting. Sleep data were stored computer following the International 10–20 System. Data showed that congenital hypothyroidism infants exhibited higher frequency of central apnea, hypopnea, and arousals in comparison to controls. Particularly, central apnea index decreased with age in the control group but not in congenital hypothyroidism group. Regarding to cyclic alternating pattern measurements, congenital hypothyroidism infants exhibit a higher frequency in the percentage of A3 subtype (electroencephalographic desynchrony) and conversely a lower percentage of A1 subtype (electroencephalographic synchrony), than healthy infants. An important finding of this study is the positive correlation between A1 mean duration and age, which is bigger in control group than in congenital hypothyroidism group (time duration in control group (0.52 s/month) versus congenital hypothyroidism group (0.1 s/month). Infants with congenital hypothyroidism showed an increase of A3 subtype, of central apnea, and of arousals. The reduction of percentage and mean duration of A1 subtype could be a valuable indicator of sleep development in patients with congenital hypothyroidism and healthy infants.

Use of Chest Wall EMG to Classify Hypopneas as Obstructive or Central.

To compare classification of hypopneas as obstructive or central based on an effort signal derived from surface chest wall electromyography (CW-EMG-EF) coupled with airflow amplitude versus classification using The AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications (AASM Scoring Manual) criteria; and to characterize hypopneas classified as obstructive versus central using a resistance surrogate. CW-EMG was recorded in the eighth intercostal space at the right midaxillary line. Five hypopneas were randomly selected from 65 consecutive adult clinical positive airway pressure titration studies meeting study criteria. A blinded scorer classified the hypopneas based on two groups of signals: Group 1: positive airway pressure flow (PAP flow), chest and abdominal effort, and snoring; or Group 2: smoothed PAP flow (for blinding amplitude but not flattening visible) and effort (CW-EMG-EF). A resistance surrogate (CW-EMG-EF / PAP flow) normalized to a pre-event breath was compared between obstructive and central hypopneas classified by AASM Scoring Manual criteria. The percentage agreement (Group 1 versus Group 2) was 92% and the kappa was 0.75 (95% confidence interval 0.65 to 0.85). The resistance surrogate was significantly higher in obstructive hypopneas versus central hypopneas during the first and second half of hypopneas. The resistance surrogate (mean ± standard deviation) for the second half of hypopnea was obstructive: 7.59 ± 7.24 versus central: 1.27 ± 0.56, P < .001). The resistance surrogate increased from the first to second half of hypopnea only for obstructive hypopneas. CW-EMG provides a useful complementary signal for hypopnea classification and a resistance surrogate based on CW-EMG is much higher in hypopneas classified as obstructive by AASM Scoring Manual criteria.

Polysomnography for the management of oxygen supplementation therapy in infants with chronic lung disease of prematurity

Aim: Some infants with bronchopulmonary dysplasia (BPD) may require oxygen supplementation at home but a role for overnight polysomnography (PSG) in the management of home oxygen therapy has been rarely described.Methods: Forty-one infants with BPD born at less than 30 weeks gestational age were discharged with continuous home oxygen supplementation therapy between 2010 and 2013. PSG data were recorded on oxygen supplementation versus room air at median corrected age of 2 months (range 1–5 months) (first PSG after discharge to home). Those infants who continued oxygen supplementation therapy at home had at least one more PSG before oxygen therapy was discontinued (last PSG). We also collected PSG data in 10 healthy term infants (median age 3.5 months; range 2–4 months).Results: In infants with BPD in room air, increased numbers of central apneas, hypopneas, and SaO2 desaturations were the predominant PSG features with a median apnea–hypopnea index (AHI) of 16.8 events per hour (range 0–155). On oxygen supplementation therapy, median AHI dramatically improved (2.2, range 0–22; p < .001) and was not different from control infants (2.0, range 0–3.9; p = .31). AHI on room air at the last PSG when home oxygen was ceased was 4.1 per hour (range 0–13.8) slightly higher than in healthy infants.Conclusion: Central sleep disordered breathing in infants with BPD dramatically normalizes with low flow nasal cannula home oxygen therapy and improves with age. Mild central sleep disordered breathing remains detectable, although much improved, when compared with healthy infants at the time when the decision to cease home oxygen therapy was made by the physician.