BACKGROUND Use of polysomnography (PSG) is the gold standard of diagnosis and measurement of treatment effectiveness for paediatric obstructive sleep apnoea (OSA). Although adenotonsillectomy (T&A) is effective in diminishing the apnoea-hypopnoea index (AHI), a meta-analysis of postoperative changes for all other PSG parameters and outcome comparisons between obese and non-obese children following T&A have never been conducted. OBJECTIVE OF REVIEW To comprehensively review polysomnographic findings after surgery for obese and non-obese children with OSA. SEARCH STRATEGY Study protocol was registered on PROSPERO (CRD42013004737). Two authors independently searched databases including PubMed, MEDLINE, EMBASE and Cochrane Review from January 1997 to July 2014. The keywords used included the following: sleep apnea, OSA, sleep apnea syndromes, tonsillectomy, adenoidectomy, infant, child, adolescent, and Humans. EVALUATION METHOD A comprehensive systematic review and meta-analysis for literature for OSA children treated by T&A with polysomnography data. Random-effects model was applied to determine postoperative sleep parameter changes and the surgical success rate between obese and non-obese groups. The quality of studies was assessed using the Newcastle-Ottawa Scale. RESULTS In total, 51 studies with 3413 subjects were enrolled. After surgery, sleep architecture was altered by a significant decrease in sleep stage 1, and an increase in slow-wave sleep and the rapid eye movement stage, and enhanced sleep efficiency. The mean difference between pre- and postoperative was a significant reduction of 12.4 event/h in AHI, along with a reduction of obstructive index, hypopnoea index, central index and arousal index. Mean and minimum oxygen saturation increased significantly after surgery. The overall success rate was 51% for postoperative AHI <1 (obese versus non-obese versus combined, 34% versus 49% versus 56%), and 81% for AHI <5 (obese versus non-obese versus combined, 61% versus 87% versus 84%). Meta-regression analyses demonstrate that postoperative AHI was positively correlated with AHI and body mass index z score before surgery. CONCLUSIONS Meta-analysis of current literature shows T&A offers prominent improvement in a variety of sleep parameters. Improvements in non-obese children exceeded those for obese children. Postoperative residual OSA remained in roughly half of the children, especially those with severe disease and obesity, making additional treatment strategies and/or long-term follow-up highly desirable.

Polysomnographic findings after adenotonsillectomy for obstructive sleep apnoea in obese and non-obese children: a systematic review and meta-analysis.

In this paper, we consider the application of texture features for antitank landmine detection in ground- penetrating-radar data in the difficult scenario of very high clutter environments. In particular, we develop a technique for 3-D texture feature extraction, and we compare the results for landmine/clutter discrimination using classifiers that are built on 3-D as well as on 2-D texture feature sets. Our results indicate performance improvements across several different challenging testing scenarios when using the relevance-vector-machine classifiers that are trained on our 3-D feature sets as compared to the performance using the 2-D texture feature sets.

Texture Features for Antitank Landmine Detection Using Ground Penetrating Radar

Sleep is involved in the regulation of major organ functions in the human body, and disruption of sleep potentially can elicit organ dysfunction. Obstructive sleep apnea (OSA) is the most prevalent sleep disorder of breathing in adults and children, and its manifestations reflect the interactions between intermittent hypoxia, intermittent hypercapnia, increased intra-thoracic pressure swings, and sleep fragmentation, as elicited by the episodic changes in upper airway resistance during sleep. The sympathetic nervous system is an important modulator of the cardiovascular, immune, endocrine and metabolic systems, and alterations in autonomic activity may lead to metabolic imbalance and organ dysfunction. Here we review how OSA and its constitutive components can lead to perturbation of the autonomic nervous system in general, and to altered regulation of catecholamines, both of which then playing an important role in some of the mechanisms underlying OSA-induced morbidities.

/pdf/sympathetic-and-catecholaminergic-alterations-in-sleep-apnea-2wjgsn83ho.pdf

Sympathetic and catecholaminergic alterations in sleep apnea with particular emphasis on children.

Sleep disordered breathing (SDB) has adverse effects on cardiovascular health in adults, partly due to changes in autonomic activity. However, there have been limited studies in children. We analysed the impact of SDB and sleep stage on autonomic control of heart rate in 7–12-year-old children, utilizing spectral heart rate variability (HRV) as a measure of autonomic activity. Eighty children underwent overnight polysomnography. Subjects were grouped according to their obstructive apnoea–hypopnoea index (OAHI): controls, OAHI ≤1 event/h and no history of snoring; primary snorers (PS) OAHI ≤1, Mild (OAHI 1–5) and moderate/severe (MS) OAHI >5. HRV was analysed during Wake, nonrapid eye movement (NREM) 1&2, slow wave sleep (SWS) and REM. Compared with controls, total power, low (LF) and high frequency (HF) power were reduced in all SDB severities during REM. LF/HF ratio was less in MS SDB (median = 0.34; range, 0.20–0.49; p < 0.05) versus controls (0.38; 0.26–0.55; p < 0.05) and PS (0.39; 0.23–0.57; p < 0.05) during SWS. In all groups, total power, LF and HF power were highest during NREM 1&2 while LF/HF ratio was lowest during SWS. Blood pressure was elevated in SDB in all sleep states. HRV was altered in 7–12-year-old children with SDB, which may signify an overall depression of autonomic tone, perhaps a consequence of their elevated blood pressure during sleep coupled with repeated exposure to SDB event-related cardiovascular disturbance. Further research is warranted to elucidate the long-term effects on the cardiovascular system of subjects exhibiting impaired HRV and elevated BP in childhood.

/pdf/autonomic-dysfunction-in-children-with-sleep-disordered-c6lwpr4gv1.pdf

Autonomic dysfunction in children with sleep disordered breathing

Study objectives Obstructive sleep apnea syndrome (OSAS) has been associated with cardiometabolic disease in adults. In children, this association is unclear. We evaluated the effect of early adenotonsillectomy (eAT) for treatment of OSAS on blood pressure, heart rate, lipids, glucose, insulin, and C-reactive protein. We also analyzed whether these parameters at baseline and changes at follow-up correlated with polysomnographic indices. Design Data collected at baseline and 7-mo follow-up were analyzed from a randomized controlled trial, the Childhood Adenotonsillectomy Trial (CHAT). Setting Clinical referral setting from multiple centers. Participants There were 464 children, ages 5 to 9.9 y with OSAS without severe hypoxemia. Interventions Randomization to eAT or Watchful Waiting with Supportive Care (WWSC). Measurements and results There was no significant change of cardiometabolic parameters over the 7-mo interval in the eAT group compared to WWSC group. However, overnight heart rate was incrementally higher in association with baseline OSAS severity (average heart rate increase of 3 beats per minute [bpm] for apnea-hypopnea index [AHI] of 2 versus 10; [standard error = 0.60]). Each 5-unit improvement in AHI and 5 mmHg improvement in peak end-tidal CO2 were estimated to reduce heart rate by 1 and 1.5 bpm, respectively. An increase in N3 sleep also was associated with small reductions in systolic blood pressure percentile. Conclusions There is little variation in standard cardiometabolic parameters in children with obstructive sleep apnea syndrome (OSAS) but without severe hypoxemia at baseline or after intervention. Of all measures, overnight heart rate emerged as the most sensitive parameter of pediatric OSAS severity. Clinical trial registration Clinicaltrials.gov (#NCT00560859).

/pdf/the-effect-of-adenotonsillectomy-for-childhood-sleep-apnea-2vsem65yoq.pdf

The Effect of Adenotonsillectomy for Childhood Sleep Apnea on Cardiometabolic Measures.

Changes in Heart Rate Variability After Adenotonsillectomy in Children With Obstructive Sleep Apnea

This article presents a lossless compression of volumetric medical images with the improved three-dimensional (3-D) set partitioning in hierarchical tree (SPIHT) algorithm that searches on asymmetric trees. The tree structure links wavelet coefficients produced by 3-D reversible integer wavelet transforms. Experiments show that the lossless compression with the improved 3-D SPIHT gives improvement about 42% on average over two-dimensional techniques and is superior to those of prior results of 3-D techniques. In addition, we can easily apply different numbers of decomposition between the transaxial and axial dimensions, which is a desirable function when the coding unit of a group of slices is limited in size.

/pdf/lossless-compression-of-volumetric-medical-images-with-151pv8nnd7.pdf

Lossless Compression of Volumetric Medical Images with Improved Three-Dimensional SPIHT Algorithm

This paper presents a lossless compression of volumetric medical images with the improved 3-D SPIHT algorithm that searches on asymmetric trees. The tree structure links wavelet coefficients produced by three-dimensional reversible integer wavelet transforms. Experiments show that the lossless compression with the improved 3-D SPIHT gives improvement about 42% on average over two-dimensional techniques, and is superior to those of prior results of three-dimensional techniques. In addition to that, we can easily apply different numbers of decompositions between the transaxial and axial dimensions, which is a desirable function when the coding unit of a group of slices is limited in size.

/pdf/lossless-compression-of-volumetric-medical-images-with-1upoo8igy4.pdf

Lossless Compression of Volumetric Medical Images with Improved 3-D SPIHT Algorithm

Tractography using diffusion tensor magnetic resonance imaging (DT-MRI) is a method to determine the architecture of axonal fibers in the central nervous system by computing the direction of greatest diffusion in the white matter of the brain. To reduce the noise in DT-MRI measurements, a tensor-valued median filter, which is reported to be denoising and structure preserving in the tractography, is applied. In this paper, we proposed the successive Fermat (SF) method, successively using Fermat point theory for a triangle contained in the two-dimensional plane, as a median filtering method. We discussed the error analysis and numerical study about the SF method for phantom and experimental data. By considering the computing time and the image quality aspects of the numerical study simultaneously, we showed that the SF method is much more efficient than the simple median (SM) and gradient descents (GD) methods.

Regularization of DT-MR images using a successive Fermat median filtering method.

The authors propose multi texture feature vector (MTFV) classifiers to diagnose the ultrasound liver images, since single texture feature vector (i.e. coarseness, orientation, regularity, granularity etc.) from the ultrasound images was not sufficiently enough to classify the characteristics of liver diseases. In the authors' simulation, they used the Bhattacharyya distance (B-distance) and Hotelling Trace Criterion (HTC) to select the best texture feature vectors for the MTFV classifiers and obtained less classification errors than other methods using single texture feature vector. The proposed MTFV classifiers, which used the texture feature vectors and Bayes decision rule, performed well for the classification of normal, fat and cirrhosis liver.

http://ieeexplore.ieee.org/iel4/5216/14220/00652748.pdf

Dongyoun Kim

Papers

Changes in Heart Rate Variability After Adenotonsillectomy in Children With Obstructive Sleep Apnea

Lossless Compression of Volumetric Medical Images with Improved Three-Dimensional SPIHT Algorithm

Lossless Compression of Volumetric Medical Images with Improved 3-D SPIHT Algorithm

Regularization of DT-MR images using a successive Fermat median filtering method.

The design of multi texture feature vector classifiers for the diagnosis of ultrasound liver images