Causal role of immune cells in obstructive sleep apnea hypopnea syndrome:Mendelian randomization study

BACKGROUND Despite being one of the most prevalent sleep disorders,obstructive sleep apnea hypoventilation syndrome(OSAHS)has limited information on its immunologic foundation.The immunological underpinnings of certain major psychiatric diseases have been uncovered in recent years thanks to the extensive use of genome-wide association studies(GWAS)and genotyping techniques using highdensity genetic markers(e.g.,SNP or CNVs).But this tactic hasn't yet been applied to OSAHS.Using a Mendelian randomization analysis,we analyzed the causal link between immune cells and the illness in order to comprehend the immunological bases of OSAHS.AIM To investigate the immune cells'association with OSAHS via genetic methods,guiding future clinical research.METHODS A comprehensive two-sample mendelian randomization study was conducted to investigate the causal relationship between immune cell characteristics and OSAHS.Summary statistics for each immune cell feature were obtained from the GWAS catalog.Information on 731 immune cell properties,such as morphologic parameters,median fluorescence intensity,absolute cellular,and relative cellular,was compiled using publicly available genetic databases.The results'robustness,heterogeneity,and horizontal pleiotropy were confirmed using extensive sensitivity examination.RESULTS Following false discovery rate(FDR)correction,no statistically significant effect of OSAHS on immunophenotypes was observed.However,two lymphocyte subsets were found to have a significant association with the risk of OSAHS:Basophil%CD33dim HLA DR-CD66b-(OR=1.03,95%CI=1.01-1.03,P<0.001);CD38 on IgD+CD24-B cell(OR=1.04,95%CI=1.02-1.04,P=0.019).CONCLUSION This study shows a strong link between immune cells and OSAHS through a gene approach,thus offering direction for potential future medical research.

Processing obstructive sleep apnea syndrome (OSAS) data

In this study, the EEG signals were processed. Thirteen ICA algorithms were tested to verify the performance efficiency. The EEG signals were recorder using 10/20 international system, based on a 20 minute sleep recording of a severe Obstructive Sleep Apnea Syndrome (OSAS) during NREM and REM sleep. Seven channels were used to record the EEG signals which are sampled at 100 Hz. The performance analysis of the algorithms were investigated to eliminate the loss of the informative EEG signal during the data processing. The denoising results were magnified with the purpose of evaluating the robustness of the denoising algorithms. From the result we obtained, we are able to understand the denoising algorithm is more suitable to process the EEG signal with lower amplitude.

Relationship between brain—derived neurotrophic factor and cognitive function of obstructive sleep apnea/hypopnea syndrome patients

Objective:To determine the relationship between the blood serum brain-derived neurotrophic factor（BDNF） level and cognitive function deterioration in patients with obstructive sleep apnea/ hypopnea syndrome（OSAHS）,and to explore the possible mechanism of cognitive impairment. Methods:Twenty-eight male OSAHS patients and 14 normal males（as controls） were enrolled in the study.Polysomnography and the Montreal cognitive assessment（MoCA） were conducted. The blood serum BDNF levels were measured using ELISA.Results:The OSAHS group had significantly decreased blood serum BDNF levels compared with the control group（t=-10.912, P=0.000）.The blood serum BDNF level of the subjects was significantly positively associated with the MoCA score（r=0.544,P=0.000）,significantly negatively associated with the apneahypopnea index（AHI） and shallow sleep（S1+S2）（AHI:r=-0.607,P=0.000;S1+S2:r =-0.768,P= 0.000）,and significantly positively associated with the lowest SaO2（LSO）,slow wave sleep（S3+S4）, and rapid eye movement sleep（REM）（LSO:r=0.566,P = 0.000;S3+S4:r=0.778,P=0.000;REM: r=0.575,P=0.000）.Conclusions:OSAHS patients have significantly decreased blood serum BDNF levels compared with the control.Nocturnal hypoxia as well as the deprivation of slow wave sleep and REM may lead to the decreased serum BDNF level of OSAHS patients.This decreased blood serum BDNF level may contribute to the cognitive impairment in OSAHS.

Association between Serum Homocysteine and Oxidative Stress in Elderly Patients with Obstructive Sleep Apnea/hypopnea Syndrome

Objective Elderly patients with obstructive sleep apnea/hypopnea syndrome （OSAHS） has a higher risk of cardiovascular and cerebrovascular disease. However, changes of homocysteine （Hey） as markers of cardiovascular and eerebrovascular disease associated with OSAHS and their mechanism have not been elucidated so far. This study aims to investigate the changes of both serum Hcy and oxidative stress and their possible links with OSAHS in elderly patients. Methods Based on polysomnogram （PSG） and age, 83 patients with OSAHS were recruited and divided into elderly-OSAHS （n=32） and non-elderly OSAHS groups （n=51）. Fifty two subjects without OSAHS were divided into elderly control （n=29） and non-elderly control groups （n-23）. A total of 135 subjects were included in the present study. All subjects were recorded for PSG variables and the contents of homocysteine （Hcy）, malonaldehyde （MDA）, and glutathione （GSH） which were detected after sleep. Serum homocysteine was measured by cyclophorase. MDA and GSH were measured by speetrophotometer. Results （1） The serum levels of Hcy showed significant difference among the four groups （P〈0.05）. The concentrations of Hcy in elderly OSAHS patients were higher than in other groups, while those in the elderly control group were higher than in the non-elderly control; the concentrations in the non-elderly OSAHS group were higher than in the non-elderly control. （2） The concentrations of MDA and GSH changed at an equal pace with Hcy in the four groups. （3） Multielement linearity regression analysis indicated a statistically significant relationship between Hcy concentration and age, MDA, GSH, and apnea hypopnea index （AHI）. Conclusions （1） The concentrations of Hcy and oxidative stress have increased with advancing age. （2） The concentrations of Hcy and oxidative stress have further increased in the elderly patients with OSAHS. （3） Oxidative stress might cause high-level serum Hcy in the elderly patients with OSAHS.

The Change of Interleukin-6 and Tumor Necrosis Factor in Patients with Obstructive Sleep Apnea Syndrome

The levels of lipopolysaccharide (LPS) induced interleukin 6 (IL 6) and tumor necrosis factor α (TNF α) expression in culture of peripheral blood mononuclear cells (PBMC) and the plasma levels of IL 6 and TNF α in the patients with obstructive sleep apnea syndrome (OSAS) were measured and the relationship between OSAS and IL 6 or TNF α expression studied. Both IL 6 and TNF α were detected by using ELISA in 22 patients with OSAS and 16 normal controls. The levels of LPS induced IL 6 (787.82±151.97 pg/ml) and TNF α (4165.45±1501.43 pg/ml) expression in the supernatant of the culture of PBMC and plasma level of IL 6 (50.67±4.70 pg/ml) and TNF α (299.09±43.57 pg/ml) in the patients with OSAS were significantly higher than those in the normal controls (in the supernatant of the culture of PBMC: 562.69±197.54 pg/ml and 1596.25±403.08 pg/ml respectively; in the plasma: 12.69±2.75 pg/ml and 101.88±21.27 pg/ml respectively). There were significantly positive correlation between the levels of IL 6 and TNF α and the percentage of time of apnea and hyponea, as well as the percentage of time spending at SaO 2 below 90 % in the total sleep time. It was concluded that LPS induced IL 6 and TNF α levels as well as plasma IL 6 and TNF α levels in the patients with OSAS were up regulated, which may be associated with the pathogenesis of OSAS.

Evaluation of Airway Obstruction at Soft Palate Level in Male Patients with Obstructive Sleep Apnea/Hypopnea Syndrome:Dynamic 3-Dimensional CT Imaging of Upper Airway

This study examined the dynamic characteristics of upper airway collapse at soft palate level in patients with obstructive sleep apnea/hypopnea syndrome（OSAHS） by using dynamic 3-Dimensional（3-D） CT imaging.A total of 41 male patients who presented with 2 of the following symptoms,i.e.,daytime sleepiness and fatigue,frequent snoring,and apnea with witness,were diagnosed as having OSAHS.They underwent full-night polysomnography and then dynamic 3-D CT imaging of the upper airway during quiet breathing and in Muller＇s maneuver.The soft palate length（SPL）,the minimal cross-sectional area of the retropalatal region（mXSA-RP）,and the vertical distance from the hard palate to the upper posterior part of the hyoid（hhL） were compared between the two breathing states.These parameters,together with hard palate length（HPL）,were also compared between mild/moderate and severe OSAHS groups.Association of these parameters with the severity of OSAHS [as reflected by apnea hypopnea index（AHI） and the lowest saturation of blood oxygen（LSaO2）] was examined.The results showed that 31 patients had severe OSAHS,and 10 mild/moderate OSAHS.All the patients had airway obstruction at soft palate level.mXSA-RP was significantly decreased and SPL remarkably increased during Muller＇s maneuver as compared with the quiet breathing state.There were no significant differences in these airway parameters（except the position of the hyoid bone） between severe and mild/moderate OSAHS groups.And no significant correlation between these airway parameters and the severity of OSAHS was found.The position of hyoid was lower in the severe OSAHS group than in the mild/moderate OSAHS group.The patients in group with body mass index（BMI）≥26 had higher collapse ratio of mXSA-RP,greater neck circumference and smaller mXSA-RP in the Muller＇s maneuver than those in group with BMI26（P0.05 for all）.It was concluded that dynamic 3-D CT imaging could dynamically show the upper airway changes at soft palate level in OSAHS patients.All the OSAHS patients had airway obstruction of various degrees at soft palate level.But no correlation was observed between the airway change at soft palate level and the severity of OSAHS.The patients in group with BMI≥26 were more likely to develop airway obstruction at soft palate level than those with BMI26.

Detection of cognitive impairment in patients with obstructive sleep apnea hypopnea syndrome using mismatch negativity

In this experiment, 97 patients with obstructive sleep apnea hypopnea syndrome were divided into three groups （mild, moderate, severe） according to minimum oxygen saturation, and 35 healthy subjects were examined as controls. Cognitive function was determined using the mismatch negativity paradigm and the Montreal Cognitive Assessment. The results revealed that as the disease worsened, the mismatch negativity latency was gradually extended, and the amplitude gradually declined in patients with obstructive sleep apnea hypopnea syndrome. Importantly, mismatch negativity latency in severe patients with a persistent time of minimum oxygen saturation 〈 60 seconds was significantly shorter than that with a persistent time of minimum oxygen saturation 〉 60 seconds. Correlation analysis revealed a negative correlation between minimum oxygen saturation latency and Montreal Cognitive Assessment scores. These findings indicate that intermittent night-time hypoxemia affects mismatch negativity waveforms and Montrea Cognitive Assessment scores. As indicators for detecting the cognitive functional status of obstructive sleep apnea hypopnea syndrome patients, the sensitivity of mismatch negativity is 82.93%, the specificity is 73.33%, the accuracy rate is 81.52%, the positive predictive value is 85.00%, the negative predictive value is 70.21%, the positive likelihood ratio is 3, and the negative likelihood ratio is 0.23. These results indicate that mismatch negativity can be used as an effective tool for diagnosis of cognitive dysfunction in obstructive sleep apnea hypopnea syndrome patients.

Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome: one year follow-up results

·AIM: To investigate the retinal nerve fiber layer(RNFL)thickness changes in patients with obstructive sleep apnea syndrome(OSAS) for one year follow-up. To discuss the possibility of detecting tendency of glaucoma in this population by using spectral domain optical coherence tomography(3D-OCT-2000 Spectral domain).·METHODS: After polysomnographic study, all subjects(64 OSAS patients and 40 controls) underwent detailed ophthalmological examination. After these examinations,patients with glaucoma and patients who had ophthalmological and/or systemic disease were excluded from the study.Totally, 20 patients in OSAS group and five patients in controls were excluded from the study in the first examination and follow-up period. The RNFL thickness was assessed with OCT. Forty-four OSAS patients and 35 control subjects were followed up for12 mo. RNFL thickness change and OSAS patients were evaluated for severity of disease by Apnea-Hypopnea Index(AHI).·RESULTS: Forty-four OSAS patients and 35 controls were enrolled in the study. Statistically significance was found between OSAS patients and controls at the 12 thmo.Average RNFL thickness was found to be significantly lower in last measurements in OSAS patients when compared with first measurements and control subjects(P 【0.001, 0.002, respectively). There was a statistically significant correlation among AHI, and RNFL thickness(P 【0.05).·CONCLUSION: The results suggest that the patients with OSAS were related with a proportional decrease in the RNFL thickness. These patients should be followed up regularly for glaucomatous changes. Detecting more RNFL thinning in severe OSAS was important.

Intermittent hypoxia is involved in gut microbial dysbiosis in type 2 diabetes mellitus and obstructive sleep apnea-hypopnea syndrome

BACKGROUND Obstructive sleep apnea(OSA)-hypopnea syndrome(OSAHS)has been recognized as a comorbidity of type 2 diabetes mellitus(T2DM);more than half of T2DM patients suffer from OSAHS.Intermittent hypoxia(IH)plays an important role in metabolic diseases,such as obesity and OSAHS,through various mechanisms,including altering the gut microecological composition and function.Therefore,it is important to study the role of gut microbiota in T2DM patients with OSAHS,which has a high incidence and is prone to several complications.AIM To assess whether IH is involved in altering the fecal microbiome in T2DM patients with OSAHS.METHODS Seventy-eight participants were enrolled from Henan Province People’s Hospital and divided into healthy control(HC,n=26),T2DM(n=25),and T2DM+OSA(n=27)groups based on their conditions.The fecal bacterial DNA of the research participants was extracted and subjected to 16S ribosomal RNA sequencing.The clinical indices,such as insulin resistance index,homocysteine(HCY)concentration,and the concentrations of inflammatory factors in the peripheral blood,were assessed and recorded.RESULTS Group T2DM+OSA had the highest apnea-hypopnea index(AHI)(2.3 vs 3.7 vs 13.7),oxygen desaturation index(0.65 vs 2.2 vs 9.1),HCY concentration(9.6μmol/L vs 10.3μmol/L vs 13.81μmol/L)and C-reactive protein(CRP)concentrations(0.3 mg/L vs 1.43 mg/L vs 2.11 mg/L),and lowest mean oxygen saturation(97.05%vs 96.6%vs 94.7%)among the three groups.Twelve and fifteen key differences in amplicon sequence variants were identified when comparing group T2DM+OSA with groups T2DM and HC,respectively.We found progressively decreased levels of Faecalibacterium,Eubacterium,and Lachnospiraceae,and an increase in the level of Actinomyces,which strongly correlated with the HCY,CRP,fasting plasma glucose,and hemoglobin A1c concentrations,AHI,mean oxygen saturation,and insulin resistance index in group T2DM+OSA(P<0.05).CONCLUSION For T2DM patients with OSAHS,IH may be involved in selective alterations of the gut microbiota,which may affect the pathophysiological development of T2DM and DM-related complications.

COGNITIVE AND EMOTIONAL IMPAIRMENT IN OBSTRUCTIVE SLEEP APNEA SYNDROME

Objective To evaluate the emotional and cognitive status in patients with obstructive sleep apnea syndrome (OSAS), using neuropsychological tests and evoked-related potential (P3). Methods Sixteen patients diagnosed of OSAS were tested by Hamilton rating scale for anxiety (HRSA) and Hamilton rating scale for depression (HRSD). Other three groups, OSAS patient group (n=21), snoring group (n=21), and control group (n=21), were administered polysomnography (PSG), auditory evoked event-related potential (P3), and clinic memory test. The results were analyzed using general linear model (GLM) analysis and Post Hoc test. Results Twelve OSAS patients’ scores of HRSA and HRSD were beyond the normal range, 26.42 ±4.48 and 22.08 ±3.97 respectively. The auditory P3 latency in OSAS group was 363.1 ±22.9 ms (Fz), 368.57 ±28.03 ms (Cz), in snoring group 336.57 ±31.08 ms (Fz), 339.81 ±31.76 ms (Cz), in control group 340.8 ±28.7 ms (Fz), 338.29 ±29.21 ms (Cz). There were significant differences between OSAS group and snoring group, as well as control group (P< 0.05). No significant difference was seen between snoring group and control group. No significant difference was noted in P3 amplitude among three groups. Memory quotient (MQ) reduced in snoring group compared with control group. Conclusions Emotional disturbances are common clinical features in OSAS patients. Abnormal auditory P3 latency indicates the cognitive dysfunction in OSAS patients. Nocturnal hypoxaemia may play an important role on it. Snorers should be monitored because of the tendency to develop cognitive impairment.

Electrical Stimulation Therapy Improves Sleep Respiratory Parameters in Obstructive Sleep Apnea Syndrome: A Meta-analysis

Recent clinical trials have shown that electrical stimulation has beneficial effects in obstruc- tive sleep apnea syndrome （OSAS）. The purpose of this study was to evaluate the efficacy of electrical stimulation therapy for OSAS with a meta-analysis. The meta-analysis of all relative studies was per- formed through searching international literature, including PUBMED, CNKI, and EMBASE databases. This literature analysis compared all patients undergoing electrical stimulation therapy with respect to the respiratory disturbance index （RDI） and changes in sleep structure. Six studies were selected in- volving a total of 91 patients. The meta-analysis indicated that electrical stimulation therapy reduced RDI, longest apnea time, and improved the minimum SaO2. Based on the evidence found, electrical stimulation may be a potential therapy for OSAS, warranting further clinical trials.

Correlation of obstructive sleep apnea hypopnea syndrome with metabolic syndrome in snorers

Though obstructive sleep apnea hypopnea syndrome（OSAHS） and metabolic syndrome（MS） are correlated;the contributing factors for the occurrence of MS in Chinese snorers remain largely undefined.We aimed to investigate the associated pathogenesis of coexistence of OSAHS and MS in Chinese snorers.A total of 144 Chinese habitual snorers were divided into 3 groups,the control group（simple snorers）（n = 36）,the mild OSAHS group（n= 52）and the moderate-to-severe OSAHS group（n = 56）.The incidence of MS in the moderate-to-severe OSAHS group（26.8%） was significantly higher than that in the control group（8.3%）,the mild OSAHS group（11.1%） and all the OSAHS patients（19.45%）（all P 〈 0.05）.Homeostatic model assessment（HOMA） index and proinsulin（PI） were negatively correlated with nocturnal meanSpO2 and miniSpO2.Meanwhile,nocturnal SpO2 were negatively correlated with body mass index,waist and neck circumferences and diastolic blood pressure,but positively correlated with total cholesterol and high-density lipoprotein cholesterol.The study indicated that in Chinese snorers,moderate-to-severe OSAHS was closely associated with MS via nocturnal hypoxemia.

Clinical observation of soft palate-pharyngoplasty in the treatment of obstructive sleep apnea hypopnea syndrome in children

BACKGROUND Childhood obstructive sleep apnea hypopnea syndrome(OSAHS)is a common clinical disease that can cause serious complications if not treated in time.The preferred treatment for OSAHS in children is surgery.AIM To observe the effects of soft palate-pharyngoplasty on postoperative outcome,pharyngeal formation,and possible complications.METHODS A total of 150 children with snoring,hernia,and mouth breathing were selected.A polysomnography test was performed to confirm the diagnosis of OSAHS.The children were randomly divided into experimental and control groups.The experimental group underwent adenoidectomy,tonsillectomy,and soft palatepharyngoplasty.The control group underwent adenoidectomy and tonsillectomy.The t-test and chi-square test were used to compare conditions such as postoperative fever,postoperative hemorrhage,and pharyngeal reflux.Postoperative efficacy and complications were interrogated and observed in the form of outpatient follow-up and telephone follow-up at 6 mo and 1 year after surgery.The curative effects were divided into two groups:Cure(snoring,snoring symptoms disappeared)and non-cure.RESULTS The effective rate of the experimental group was significantly higher than that of the control group,but the difference was not statistically significant(P>0.05).The incidence of postoperative bleeding was lower in the experimental group.There was no postoperative pharyngeal reflux in either group.In the experimental group,the incidence of hyperthermia(body temperature exceeded 38.5°C)was lower than that in the control group.The difference in postoperative swallowing pain scores between the experimental and control groups was significant.CONCLUSION Soft palate-pharyngoplasty can more effectively enlarge the anteroposterior diameter and transverse diameter of the isthmus faucium.Compared with surgery alone,it can better treat OSAHS in children,improve the curative effect,reduce the risk of perioperative bleeding,close the surgical cavity,reduce the risk of postoperative infection,reduce the proportion of postoperative fever,and accelerate healing.Although this process takes more time,it is simple,safe,and effective.

Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome:a systematic review and Metaanalysis

AIM： To evaluate the retinal nerve fiber layer（RNFL）thickness changes in patients with obstructive sleep apnoea syndrome（OSAS）, and detect possible prevalence of glaucoma in this population.METHODS： Comprehensive studies were conducted on the Cochrane Library, Pub Med and Embase through March, 2015. Only studies that fit the selection criteria about RNFL and OSAS would be included. For the measures, we calculated the 95% confidence interval（CI）and weighted mean differences（WMD）. The systematic review and Meta-analysis was performed by Rev Man 5.2software.RESULTS： Nine case-control studies were analyzed containing a total of 1086 cases and 580 controls.Average RNFL thickness in OSAS was reduced significantly compared with healthy controls in random effects model（WMD =-2.56, 95% CI：-4.82 to-0.31, P =0.003, I2=57%）. A significant RNFL thickness reduction were found between the two groups in inferior quadrant（WMD =-3.11, 95% CI：-5.53 to-0.69, P =0.01）, superior quadrant（WMD =-2.37, 95% CI：-4.7 to 0.04, P =0.05）. In nasal quadrant（WMD =-2.54, 95% CI：-6.53 to 1.45, P =0.21） and temporal quadrant（WMD=-1.26, 95% CI：-2.19 to 0.47, P =0.15） there was no difference of RNFL thickness between the two groups.CONCLUSION： The results show that RNFL thickness is lower in patients with moderate or severe OSAS than in normal subjects or patients with mild OSAS according to the nine homogeneity studies.

Evaluation of choroidal thickness using spectral-domain optical coherence tomography in patients with severe obstructive sleep apnea syndrome: a comparative study

AIM: To assess choroidal thickness in patients with severe obstructive sleep apnea syndrome(OSAS) and compare them with healthy controls, using spectral domain optical coherence tomography(OCT).METHODS: In this observational, cross-sectional study,choroidal thicknesses of 23 newly severe OSAS patients and 23 body mass index- age- and sex-matched healthy subjects were measured using a high-speed, high-resolution frequency domain- OCT device( λ = 840 nm,26 000 A-scans/s, 5 μm axial resolution). All patients underwent a complete ophthalmic examination before the measurements. OCT measurements were taken at the same time of day(9:00 a.m.), in order to minimize the effects of diurnal variation.RESULTS: There was a statistically significant difference in median choroidal thickness between the OSAS patients(201 μm; range 145-237 μm) and the controls(324 μm; range 296-383 μm;P 【0.001). There were significant differences at all measurement points(P 【0.001 for all). The apnea-hypopnea index(AHI)values were more than 30 in all OSAS patients and the mean AHI was 48.57 ±6.54. The interexaminer intraclass correlation coefficient(ICC) for the mean choroidal thickness was 0.938(95% CI, 0.908-0.985) and ICC was greater than 0.90 for all measurement points.CONCLUSION: The decreased choroidal thickness of patients with severe OSAS might be related to the the autonomic disregulation associated with this disease.Further studies are needed to evaluate the etiopathologic relationship between choroidal thickness and OSAS.

Stem/progenitor cells and obstructive sleep apnea syndrome - new insights for clinical applications

Obstructive sleep apnea syndrome(OSAS) is a widespread disorder, characterized by recurrent upper airway obstruction during sleep, mostly as a result of complete or partial pharyngeal obstruction. Due to the occurrence of frequent and regular hypoxic events, patients with OSAS are at increased risk of cardiovascular disease, stroke, metabolic disorders, occupational errors, motor vehicle accidents and even death. Thus, OSAS has severe consequences and represents a significant economic burden. However, some of the consequences, as well as their costs can be reduced with appropriate detection and treatment. In this context, the recent advances that were made in stem cell biology knowledge and stem cell- based technologies hold a great promise for various medical conditions, including respiratory diseases. However, the investigation of the role of stem cells in OSAS is still recent and rather limited, requiring further studies, both in animal models and humans. The goal of this review is to summarize the current state of knowledge regarding both lung resident as well as circulating stem/progenitor cells and discuss existing controversies in the field in order to identify future research directions for clinical applications in OSAS. Also, the paper highlights the requisite for inter-institutional, multi-disciplinary research collaborations in order to achieve breakthrough results in the field.

Numerical analysis for the effcacy of nasal surgery in obstructive sleep apnea hypopnea syndrome

In the present study, we reconstructed upper airway and soft palate models of 3 obstructive sleep apnea-hypopnea syndrome（OSAHS） patients with nasal obstruction. The airflow distribution and movement of the soft palate before and after surgery were described by a numerical simulation method. The curative effect of nasal surgery was evaluated for the three patients with OSAHS. The degree of nasal obstruction in the 3 patients was improved after surgery. For 2 patients with mild OSAHS, the upper airway resistance and soft palate displacement were reduced after surgery. These changes contributed to the mitigation of respiratory airflow limitation. For the patient with severe OSAHS, the upper airway resistance and soft palate displacement increased after surgery, which aggravated the airway obstruction. The effcacy of nasal surgery for patients with OSAHS is determined by the degree of improvement in nasal obstruction and whether the effects on the pharynx are beneficial. Numerical simulation results are consistent with the polysomnogram（PSG） test results, chief complaints, and clinical findings, and can indirectly reflect the degree of nasal patency and improvement of snoring symptoms, and further,provide a theoretical basis to solve relevant clinical problems.

Computational Fluid Dynamics Simulation of the Upper Airway of Obstructive Sleep Apnea Syndrome by Muller Maneuver

This study aimed to use computer simulation to describe the fluid dynamic characteristics in patients with obstructive sleep apnea syndrome（OSAS） and to evaluate the difference between during quiet respiration and the Muller maneuver（MM）. Seven patients with OSAS were involved to perform computed tomographic（CT） scanning during quiet respiration and the MM. CT data in DICOM format were transformed into an anatomically three-dimensional computational fluid dynamics（CFD） model of the upper airway. The velocity magnitude, relative pressure, and flow distribution were obtained. Numerical simulation of airflow was performed to discuss how the MM affected airflow in the upper airway. To measure the discrepancy, the SPSS19.0 software package was utilized for statistic analysis. The results showed that the shape of the upper airway became narrower, and the pressure decreased during the MM. The minimal cross-sectional area（MCSA） of velopharynx was significantly decreased（P〈0.05） and the airflow velocity in MCSAs of velopharynx and glossopharynx significantly accelerated（P〈0.05） during the MM. This study demonstrated the possibility of CFD model combined with the MM for understanding pharyngeal aerodynamics in the pathophysiology of OSAS.

The Diagnosis Value and Its Implication of Impulse Oscillometry in Obstructive Sleep Apnea Syndrome Patients

The change of measurements of impulse oscillometry (105) in obstructive sleep apnea syn- drome (OSAS) patients and its mechanism were observed. The respiratory impedance was measured by using IOS technique and polysomnography (PSG) was monitored synchronously in 36 OSAS pa- tients,14 patients with chronic obstructive pulmonary disease (COPD) and 12 normal controls. Re- sults showed that R20 in OSAS group was significantly higher than in COPD group and control group (P<0.01). R5-R20 in OSAS group was lower than that in COPD group, but significantly higher than that in control group(P<0. 01). The levels of R20 and R5-R20 were positively correlated with severity degree of the disease. In addition, apnea-hyponea index (AHI) was positively correlated with R5 and R20 with the correlation index (r)being 0. 66 and 0. 86 respectively. The lowest SO2 was negatively correlated with R5 and R5-R20, with r being-0. 66 and- 0. 79 respectively. The mean SO2 was negatively correlated with R5 and R5-R20 with r being-0. 81 and-0. 69 respectively. IOS technique could be used as a valuable tool for assessing the degree of upper airway obstruction in the patients with OSAS, and could help to explore its pathological mechanism.

Serum Level of Vascular Endothelial Growth Factor in Patients with Obstructive Sleep Apnea Hypopnea Syndrome

To explore the relationship between the serum vascular endothelial growth factor （VEGF） level and the severity of obstructive sleep apnea hypopnea syndrome （OSAHS）, the concentrations of serum VEGF in 40 OSAHS patients and 9 healthy controls were measured by using ELISA method. Meanwhile the correlation between the concentration of VEGF and parameters of polysomnography （PSG） was examined. Our results showed that the concentrations of VEGF were significantly higher in OSAHS patients with severe hypoxia （536.8±334.7 pg/mL） than in those with mild hypoxia （329.2±174.7 pg/mL） and healthy controls （272. 8±211.0 pg/mL） （P〈0.05 for both）. The concentrations of VEGF were also significantly higher in OSAHS patients with hypertension （484.5±261.4 pg/mL） than in those without hypertension （311.0±158.4 pg/mL） and healthy controls （272. 8±211.0 pg/mL） （P〈0.05 for both）. There was a positive correlation between the concentration of VEGF and the apnea hypopnea index （AHI） （r=0.34, P〈0.05）. It is concluded that the concentration of the serum VEGF is positively related to the severity of OSAHS. The elevated serum VEGF level may be involved in the pathogenesis of the complications of obstructive sleep apnea hypopnea syndrome.