Recurrent Obstructive Sleep Apnea Research Articles

Detecting Obstructive Apnea Episodes using Dynamic Bayesian Networks and ECG-based Time-Series.

In this study, we proposed an automatic detector for obstructive apnea episodes using only ECG-based time-series from a single-ECG channel. Several obstructive apnea episodes were provoked for different separated sequences of 15 minutes in anesthetized Sprague-Dawley rats. In this recurrent obstructive sleep apnea (OSA) model, each episode lasted 15s, while the number of total events per sequence was randomly selected. The beat-to-beat interval ( RR) and the R-wave amplitude ( Ra) time-series were extracted and processed for each sequence, and used to train Dynamic Bayesian Networks with different lags. An optimal trade-off between the lag ( L) and RMSE values was considered to select the best model to be used when detecting apnea episodes. The selected models were then used to estimate the occurrence probability of apnea episodes, p(At), by using a filtering approach. Finally, the time-series of the estimated probabilities were post-processed using non-overlapped 15-s epochs, to determine whether they are classified as apneic or non-apneic segments. Results showed that those lagged models with orders greater than 5, presented suitable RMSE values and become more sensitive as the order increased. A detection threshold of 0.2 seems to provide the best apnea detection performance overall, with Acc=0.81, Se=0.83 and Sp=0.79, using two ECG parameters and L=10. Clinical relevance- Dynamic Bayesian Networks represent a powerful tool to develop personalized models for apnea detection and diagnosis in OSA patients.

Hypoxia-induced Effects on ECG Depolarization by Time Warping Analysis during Recurrent Obstructive Apnea.

In this work, we evaluated a non-linear approach to estimate morphological variations in ECG depolarization, in the context of intermittent hypoxia (IH). Obstructive apnea sequences were provoked for 15 minutes in anesthetized Sprague-Dawley rats, alternating with equal periods of normal breathing, in a recurrent obstructive sleep apnea (OSA) model. Each apnea episode lasted 15 s, while the frequency used for each sequence was randomly selected. Average heartbeats obtained before the start and at the end of each episode, were delineated to extract only the QRS wave. Then, the segmented QRS waves were non-linearly aligned using the dynamic time warping (DWT) algorithm. Morphological QRS changes in both the amplitude and temporal domains were estimated from this alignment procedure. The hypoxic and basal segments were analyzed using ECG (lead I) recordings acquired during the experiment. To assess the effects of IH over time, the changes relative to the basal QRS wave were determined, in the intervals prior to each successive events until the end of the experiment. The results showed a progressive increase in the amplitude and time-domain morphological markers of the QRS wave along the experiment, which were strongly correlated with the changes in traditional QRS markers (r ≈ 0.9). Significant changes were found between pre-apnea and hypoxic measures only for the time-domain analysis (p<0.001), probably due to the short duration of the simulated apnea episodes.Clinical relevance Increased variability in ECG depolarization morphology during recurrent hypoxic episodes would be closely related to the expression of cardiovascular dysfunction in OSA patients.

Adenoidectomy for Obstructive Sleep Apnea in Children.

Adenotonsillectomy is the recommended treatment for children with obstructive sleep apnea (OSA). Since adenoidectomy alone may be associated with significantly lower morbidity, mortality, and cost, we aimed to investigate whether adenoidectomy alone is a reasonable and appropriate treatment for children with OSA. Five-hundred fifteen consecutive children diagnosed with moderate-to-severe OSA (apnea-hypopnea index > 5) based on polysomnography and who underwent adenoidectomy or adenotonsillectomy were reevaluated after 17-73 months (mean 41) for residual or recurrent OSA using a validated questionnaire (Pediatric Sleep Questionnaire, PSQ). Failure of OSA resolution was defined as a positive mean PSQ score ≥ 0.33. Contribution of age, obesity, tonsil size, and OSA severity at baseline to adenoidectomy or adenotonsillectomy failure was examined. Positive PSQ score occurred in 15% of the entire sample and was not influenced by age or gender. No difference in failure rate was observed between adenoidectomy and adenotonsillectomy for children who were not obese with apnea-hypopnea index < 10 and had small tonsils (< 3). Children with apnea-hypopnea index ≥ 10 and/or tonsil size ≥ 3 showed a higher failure rate after adenoidectomy compared to adenotonsillectomy (20% versus 9.8%, p = 0.028). We suggest that subjective, long term outcomes of adenoidectomy are comparable to those of adenotonsillectomy in non-obese children under 7 years old with moderately OSA and small tonsils. Hence, adenoidectomy alone is a reasonable option in some children. Future prospective randomized studies are warranted to define children who may benefit from adenoidectomy alone and those children in whom adenoidectomy alone is unlikely to succeed.

Myofunctional Therapy to Treat Obstructive Sleep Apnea: A Systematic Review and Meta-analysis.

To systematically review the literature for articles evaluating myofunctional therapy (MT) as treatment for obstructive sleep apnea (OSA) in children and adults and to perform a meta-analysis on the polysomnographic, snoring, and sleepiness data. Web of Science, Scopus, MEDLINE, and The Cochrane Library. The searches were performed through June 18, 2014. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement was followed. Nine adult studies (120 patients) reported polysomnography, snoring, and/or sleepiness outcomes. The pre- and post-MT apneahypopnea indices (AHI) decreased from a mean ± standard deviation (M ± SD) of 24.5 ± 14.3/h to 12.3 ± 11.8/h, mean difference (MD) -14.26 [95% confidence interval (CI) -20.98, -7.54], P < 0.0001. Lowest oxygen saturations improved from 83.9 ± 6.0% to 86.6 ± 7.3%, MD 4.19 (95% CI 1.85, 6.54), P = 0.0005. Polysomnography snoring decreased from 14.05 ± 4.89% to 3.87 ± 4.12% of total sleep time, P < 0.001, and snoring decreased in all three studies reporting subjective outcomes. Epworth Sleepiness Scale decreased from 14.8 ± 3.5 to 8.2 ± 4.1. Two pediatric studies (25 patients) reported outcomes. In the first study of 14 children, the AHI decreased from 4.87 ± 3.0/h to 1.84 ± 3.2/h, P = 0.004. The second study evaluated children who were cured of OSA after adenotonsillectomy and palatal expansion, and found that 11 patients who continued MT remained cured (AHI 0.5 ± 0.4/h), whereas 13 controls had recurrent OSA (AHI 5.3 ± 1.5/h) after 4 y. Current literature demonstrates that myofunctional therapy decreases apnea-hypopnea index by approximately 50% in adults and 62% in children. Lowest oxygen saturations, snoring, and sleepiness outcomes improve in adults. Myofunctional therapy could serve as an adjunct to other obstructive sleep apnea treatments.

Pontine A7 and A5 noradrenergic neuronal groups mediate long‐term facilitation of hypoglossal motor activity induced by episodic airway obstruction

In obstructive sleep apnea (OSA), decreased noradrenergic activation of genioglossus muscle during REM sleep results in repetitive upper airway occlusion, a neurodegenerative process that aggravates with age. Episodic end‐expiratory airway occlusion simulating OSA in anesthetized rats has been shown to induce a vagally‐mediated and noradrenergic‐dependent long‐term facilitation (LTF) of genioglossus muscle activity (Tadjalli et al, J Neurosci, 2010). To identify the brainstem noradrenergic pathways mediating this effect, we applied episodic end‐expiratory tracheal occlusion (10 sec x 12 episodes) in 6 urethane‐anesthetized rats to induce genioglossus LTF and reveal corresponding cFos expressions in the affected brainstem pathways, in comparison to 3 control rats in which tracheal occlusion was not performed. We found that the percentage of cFos immunopositive neurons was significantly higher in A7 and A5 noradrenergic groups in experimental rats than that in control rats (32.9±5.3% vs. 0.7±0.7% for A7 and 34.8±7.2% vs. 5.4±5.4% for A5, P&lt;0.01), while the expression of cFos was not significantly changed in A6 (locus coeruleus) and other medullary noradrenergic groups. In the second group of experiments, we examined the LTF induction after inhibition of A7 or A5 by microinjection of α2‐adrenoreceptor agonist clonidine. We found that after inhibition of either A7 (n=8) or A5 (n=4), the induction of genioglossus LTF was blocked. These studies demonstrated that the pontine noradrenergic neuronal groups A7 and A5 played a key role in the vagally‐mediated genioglossus LTF which, once fully developed, may help to defend against recurrent OSA. (Supported by HL093225)

Alternatives to tracheostomy in infants and children with obstructive sleep apnea

Purpose: Since 1989, 70 children have been treated surgically with varying degrees of obstructive sleep apnea (OSA). Of these, 29 patients had completely failed conventional medical and surgical treatment and were considered tracheostomy (T) candidates, whereas five had previously undergone T for severe OSA as infants and did not respond to standard decannulation protocols. The preoperative diagnoses were cerebral palsy (n = 5), Down's syndrome (n = 5), hemifacial microsomia (n = 4), Pierre Robin sequence (n = 6), and a mixed group of craniofacial disorders (n = 14). The patients ranged in age from 2.5 weeks to ≥18 months (mean, 7.32 years). Preoperatively, four patients were on ventilators and one suffered a cardiac arrest, attesting to the severity of OSA. Methods: To enlarge the caliber of the airway, each patient underwent an aggressive surgical treatment protocol. All sites of upper airway obstruction were treated simultaneously by a combination of craniofacial skeletal expansion and soft-tissue reduction. Results: Tracheostomy was avoided in 90.4% of patients. Temporary or “permanent T” were required in three patients (9.6%). One patient with cerebral palsy had recurrent OSA and died. A second patient with severe laryngotracheomalacia and retrognathia who did not respond to apnea surgery underwent a tracheostomy and ultimately died of pulmonary causes. Four patients (7.8%) required supplemental home oxygen or continuous positive airway pressure. The average preoperative respiratory disturbance index, defined as the average number of apneic and hypopneic events per hour of sleep, dropped from 25.9 to 4.4 after surgery. The average lowest recorded oxygen saturation during overnight polysomnography rose from 61% to 92% after surgery. Of the five patients with permanent T, four had thus far been decannulated. Complications occurred in 10 patients, 50% of which were related to minor problems with mandibular distraction devices. Conclusion: Our results confirm the efficacy of an aggresive surgical approach to the treatment of OSA in children, avoiding the necessity for tracheostomy or permitting decannulation of permanent T in the majority of cases.

Laryngomalacia: a cause for early near miss for SIDS

Six infants had recurrent apnea of infancy episodes (near miss sudden infant death syndrome) during their neonatal period. Physical examination and laboratory investigation were normal. Polygraphic sleep monitoring revealed recurrent obstructive sleep apnea. These infants underwent fiberoptic endoscopy which showed that airway obstruction occurred at the laryngeal orifice as a result of laryngomalacia. It is suggested that laryngomalacia may be a cause for early apnea of infancy.