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  1. Lee YK, Bister M, Salleh YM, Blanchfield P
    PMID: 18003041
    Effect of amplitude criteria on the operating characteristics of algorithms for detecting OSAH events based on the analysis of oxygen saturation alone is investigated. The objective is to establish that there exists an oxygen desaturation level that leverages these algorithms to be more sensitive or more specific, irrespective of the differences in detection mechanism and database, a first ever attempt. Linear classification of algorithms from previous studies discovered that a drop in oxygen saturation of 3% or less makes the detection algorithms more sensitive while a drop of 4% or more makes it more specific. Results from two algorithms developed here also supported this. This finding explains the contradiction cited in the performance of algorithms from the different authors, which casts doubts on their detection ability. It could lead to the establishment of standard oxygen desaturation levels for screening and diagnosis of moderate/severe OSA, thus providing a more credible comparison basis for automated detection algorithms or even clinical tests.
    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology*
  2. Faizal WM, Ghazali NNN, Badruddin IA, Zainon MZ, Yazid AA, Ali MAB, et al.
    Comput Methods Programs Biomed, 2019 Oct;180:105036.
    PMID: 31430594 DOI: 10.1016/j.cmpb.2019.105036
    Obstructive sleep apnea is one of the most common breathing disorders. Undiagnosed sleep apnea is a hidden health crisis to the patient and it could raise the risk of heart diseases, high blood pressure, depression and diabetes. The throat muscle (i.e., tongue and soft palate) relax narrows the airway and causes the blockage of the airway in breathing. To understand this phenomenon computational fluid dynamics method has emerged as a handy tool to conduct the modeling and analysis of airflow characteristics. The comprehensive fluid-structure interaction method provides the realistic visualization of the airflow and interaction with the throat muscle. Thus, this paper reviews the scientific work related to the fluid-structure interaction (FSI) for the evaluation of obstructive sleep apnea, using computational techniques. In total 102 articles were analyzed, each article was evaluated based on the elements related with fluid-structure interaction of sleep apnea via computational techniques. In this review, the significance of FSI for the evaluation of obstructive sleep apnea has been critically examined. Then the flow properties, boundary conditions and validation of the model are given due consideration to present a broad perspective of CFD being applied to study sleep apnea. Finally, the challenges of FSI simulation methods are also highlighted in this article.
    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology*
  3. Liam CK, Lim KH, Wong CMM, Lau WM, Tan CT
    Med J Malaysia, 2001 Mar;56(1):10-7.
    PMID: 11503285
    Introduction: The flow-volume curves of patients with obstructive sleep apnoea (OSA) obtained during the awake state are frequently abnormal.
    Objective: To determine 1) the relationship between the awake respiratory function and the severity of sleep-disordered breathing in a group of Malaysian patients with the OSA syndrome and 2) the frequency of flow-volume curve abnormality in these patients.
    Materials and methods: A retrospective analysis of the data from respiratory function tests during wakefulness and nocturnal polysomnography was performed on 48 patients with OSA. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) and the lowest oxygen saturation during sleep (SPO2nadir).
    Results: AHI had a significant relationship with alveolar-arterial oxygen gradient (r=0.34, p=0.046) and SPO2nadir (r=0.049, p<0.001) but not with any anthropometric parameter or the other awake respiratory function variables measured SPO2nadir, has a significant relationship with body mass index (r=0.54, P<0.001), neck circumference (r=-0.39, p=0.013), awake room air PaO2 (r=0.61, p<0.001), alveolar-arterial oxygen gradient (r=-0.41, p=0.015) and baseline supine SpO2 (r=0.53, p<0.001). there was no correlation between SPO2nadir and any spirometric or static lung volume parameters. The maximum inspiratory and maximum expiratory flow volume curves of 26 patients (54%) showed a ratio of forced expiratory flow to forced inspiratory flow at mid-vital capacity (FEF50/FIF50) greater than one. In addition, flow oscillations (the ‘sawtooth’ sign) were noted in the inspiratory and/or expiratory flow-volume curves of 21 patients (44%), 9 of who did not have an FEF50/FIF50>1. Altogether, the maximum flow-volume curves during wakefulness of 35 (&3%) of the 48 patients showed variable upper airway obstruction and/or flow oscillations. However, the presence of these two upper airway abnormalities, either occurring alone or together did not have an effect on the severity of OSA as measured by the AHI or SPO2nadir.
    Conclusions: Abnormalities of the flow-volume loop consistent with inspiratory flow limitation and/or upper airway instability during wakefulness are common in patients with the OSA syndrome. The degree of oxygen desaturation during sleep in these patients as related to their awake oxygenation status.
    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology*
  4. Tan SK, Leung WK, Tang ATH, Zwahlen RA
    PLoS One, 2017;12(10):e0185951.
    PMID: 29016682 DOI: 10.1371/journal.pone.0185951
    BACKGROUND: Mandibular setback osteotomies potentially lead to narrowing of the pharyngeal airways, subsequently resulting in post-surgical obstructive sleep apnea (OSA).

    OBJECTIVE: To summarize current evidence from systematic reviews that has evaluated pharyngeal airway changes after mandibular setback with or without concomitant upper jaw osteotomies.

    METHODOLOGY: PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched with no restriction of language or date. Systematic reviews studying changes in pharyngeal airway dimensions and respiratory parameters after mandibular setback with or without concomitant upper jaw osteotomies have been identified, screened for eligibility, included and analyzed in this study.

    RESULTS: Six systematic reviews have been included. While isolated mandibular setback osteotomies result in reduced oropharyngeal airway dimensions, the reduction is lesser in cases with concomitant upper jaw osteotomies. Only scarce evidence exists currently to what happens to naso- and hypo-pharyngeal airways. There is no evidence for post-surgical OSA, even though some studies reported reduced respiratory parameters after single-jaw mandibular setback with or without concomitant upper jaw osteotomies.

    CONCLUSION: Although mandibular setback osteotomies reduce pharyngeal airway dimensions, evidence confirming post-surgical OSA was not found. Nevertheless, potential post-surgical OSA should be taken into serious consideration during the treatment planning of particular orthognathic cases. As moderate evidence exists that double-jaw surgeries lead to less compromised post-surgical pharyngeal airways, they should be considered as the method of choice especially in cases with severe dentoskeletal Class III deformity.

    STUDY REGISTRATION: PROSPERO (registration number: CRD42016046484).

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology*
  5. Fang SY, Wan Abdul Halim WH, Mat Baki M, Din NM
    Graefes Arch Clin Exp Ophthalmol, 2018 Apr;256(4):783-790.
    PMID: 29492688 DOI: 10.1007/s00417-018-3919-7
    PURPOSE: Obstructive sleep apnea syndrome (OSAS) patients are at risk of glaucoma but the risk increases if they have higher intraocular pressure (IOP) while sleeping. We aim to evaluate the postural effect of upright and prolong supine positions on IOP in these patients.

    METHODS: This is a cross-sectional study involving 27 patients with symptoms of OSAS seen at a tertiary institutional center and 25 normal controls performed between June 2015 and June 2016. All patients and controls underwent a polysomnography (PSG) test and were diagnosed with OSAS based on the apnea-hypopnea index (AHI). Patients are those with OSAS symptoms and had AHI > 5, whereas controls are staffs from the ophthalmology clinic without clinical criteria for OSAS and had PSG result of AHI

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology
  6. Doufas AG, Shafer SL, Rashid NHA, Kushida CA, Capasso R
    Anesthesiology, 2019 02;130(2):213-226.
    PMID: 30247202 DOI: 10.1097/ALN.0000000000002430
    BACKGROUND: Evidence suggests that obstructive sleep apnea promotes postoperative pulmonary complications by enhancing vulnerability to opioid-induced ventilatory depression. We hypothesized that patients with moderate-to-severe obstructive sleep apnea are more sensitive to remifentanil-induced ventilatory depression than controls.

    METHODS: After institutional approval and written informed consent, patients received a brief remifentanil infusion during continuous monitoring of ventilation. We compared minute ventilation in 30 patients with moderate-to-severe obstructive sleep apnea diagnosed by polysomnography and 20 controls with no to mild obstructive sleep apnea per polysomnography. Effect site concentrations were estimated by a published pharmacologic model. We modeled minute ventilation as a function of effect site concentration and the estimated carbon dioxide. Obstructive sleep apnea status, body mass index, sex, age, use of continuous positive airway pressure, apnea/hypopnea events per hour of sleep, and minimum nocturnal oxygen saturation measured by pulse oximetry in polysomnography were tested as covariates for remifentanil effect site concentration at half-maximal depression of minute ventilation (Ce50) and included in the model if a threshold of 6.63 (P < 0.01) in the reduction of objective function was reached and improved model fit.

    RESULTS: Our model described the observed minute ventilation with reasonable accuracy (22% median absolute error). We estimated a remifentanil Ce50 of 2.20 ng · ml (95% CI, 2.09 to 2.33). The estimated value for Ce50 was 2.1 ng · ml (95% CI, 1.9 to 2.3) in patients without obstructive sleep apnea and 2.3 ng · ml (95% CI, 2.2 to 2.5) in patients with obstructive sleep apnea, a statistically nonsignificant difference (P = 0.081). None of the tested covariates demonstrated a significant effect on Ce50. Likelihood profiling with the model including obstructive sleep apnea suggested that the effect of obstructive sleep apnea on remifentanil Ce50 was less than 5%.

    CONCLUSIONS: Obstructive sleep apnea status, apnea/hypopnea events per hour of sleep, or minimum nocturnal oxygen saturation measured by pulse oximetry did not influence the sensitivity to remifentanil-induced ventilatory depression in awake patients receiving a remifentanil infusion of 0.2 μg · kg of ideal body weight per minute.

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology*
  7. Nadarajah S, Samsudin A, Ramli N, Tan CT, Mimiwati Z
    Optom Vis Sci, 2017 10;94(10):981-985.
    PMID: 28858045 DOI: 10.1097/OPX.0000000000001117
    SIGNIFICANCE: To our knowledge, this is the first time a study looking at the association between corneal hysteresis (CH) and obstructive sleep apnea syndrome (OSAS) severity has been reported. We provide evidence that CH is lower in OSAS and speculate on the possible causes.

    PURPOSE: The present study aims to look at the association between CH and severity of OSAS, and whether CH could be another link between OSAS and the development of glaucoma.

    METHODS: This was a cross-sectional, observational study at the University Malaya Medical Centre, Kuala Lumpur. Patients undergoing polysomnography for assessment of OSAS were recruited. We measured central corneal thickness (CCT) using optical biometry, and CH using ocular response analysis. Intraocular pressure (IOP) and Humphrey visual field (HVF) indices were also measured. The Apnea Hypopnea Index (AHI) divided patients into normal, mild, moderate, and severe OSAS categories. The normal and mild categories (47.9%) were then collectively called group 1, and the moderate and severe categories (52.1%) were called group 2. T tests, Pearson correlation tests, and general linear model analysis were performed, with P .05). CH correlated negatively with AHI (r = -0.229, P = .013) and positively with lowest oxygen saturation (r = 0.213, P = .022).

    CONCLUSIONS: CH is lower in moderate/severe OSAS than in normal/mild cases. This may be another link between OSAS and the development of glaucoma; further studies are indicated to determine the significance of this connection.

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology
  8. Azman M, Sani A, Kamaruddin NA
    Ann Saudi Med, 2014;34(6):476-81.
    PMID: 25971819 DOI: 10.5144/0256-4947.2014.476
    BACKGROUND AND OBJECTIVES: Obstructive sleep apnea (OSA) is a common disease affecting middle-aged patients and is associated with significant cardiovascular, cerebrovascular, and metabolic complications. Current evidences show inconclusive association between OSA and insulin resistance (IR). This study aims to examine the possible correlation between OSA parameters and IR.

    DESIGN AND SETTINGS: This was a cross-sectional study to examine the association between OSA parameters and IR using homeostasis model assessment (HOMA) on patients who underwent polysomnogram (PSG) in a tertiary center between March 2011 and March 2012 (1 year).

    PATIENTS AND METHODS: A total of 62 patients underwent PSG within the study period, of which 16 patients were excluded due to abnormal fasting blood sugar. Information on patients' medical illnesses, medications, and Epworth sleepiness scale (ESS) was obtained. Patients' body mass index (BMI), neck circumference, and waist circumference (WC) were measured. Blood samples were collected after 8 hours of fasting to measure HOMA-IR value. Overnight PSG was performed for all patients. Data was recorded and analyzed using SPSS, version 12.0 (SPSS Inc, Chicago, USA).

    RESULTS: The prevalence of IR in OSA patients was 64.3%. There was significant correlation between OSA parameters (apnea-hypopnea index, ESS, BMI, and WC) and HOMA-IR with correlation coefficient of 0.529, 0.224, 0.261, and 0.354, respectively.

    CONCLUSION: A linear correlation exists between OSA parameters and IR concluding a definite causal link between OSA and IR. IR screening is recommended in severe OSA patients.

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology
  9. Abdullah B, Rajet KA, Abd Hamid SS, Mohammad WM
    Sleep Breath, 2011 Dec;15(4):747-54.
    PMID: 20957444 DOI: 10.1007/s11325-010-0431-7
    OBJECTIVES: We aimed to evaluate the severity of upper airway obstruction at the retropalatal and retroglossal regions in obstructive sleep apnea (OSA) patients.

    METHODOLOGY: This is a descriptive cross-sectional study at the Sleep Clinic, Department of Otorhinolaryngology-Head and Neck Surgery. Flexible nasopharyngolaryngoscopy was performed in seated erect and supine position. Retropalatal and retroglossal regions were continuously recorded during quiet breathing and Mueller's maneuver in both positions. Captured images were measured using Scion Image software and narrowing rate was calculated. Level of each site was classified based on Fujita classification and severity of obstruction using Sher scoring system for Mueller's maneuver.

    RESULTS: A total of 59 patients participated in this study. Twenty-nine (49.2%) participants had type 1 (retropalatal) obstruction, 23 (38.9%) had type 2 (retropalatal and retroglossal), and seven (11.9%) in type 3 (retroglossal) obstruction. Fifty (84.7%) of the patients have severe obstruction at the retropalatal region in supine position (SRP) followed by 35 (59.3%) at retropalatal region in erect position (ERP), 27 (45.8%) at retroglossal region in supine position (SRG) and eight (13.5%) at retroglossal region in erect position (ERG). The average oxygen saturation showed significant association in ERP (P = 0.012) and SRP (P < 0.001), but not significant in ERG and SRG.

    CONCLUSIONS: Videoendoscopy utilizing flexible nasopharyngolaryngoscopy and Scion Image software is reliable, minimally invasive, and useful as an office procedure in evaluating the multilevel obstruction of upper airway in OSA patients. The retropalatal region has more severe obstruction compared with retroglossal region either in erect or supine position.

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology
  10. Lim EWL, Chee ML, Sabanayagam C, Majithia S, Tao Y, Wong TY, et al.
    Invest Ophthalmol Vis Sci, 2019 05 01;60(6):1889-1897.
    PMID: 31042796 DOI: 10.1167/iovs.19-26810
    Purpose: The purpose of this study was to investigate the association between sleep (duration and quality) and symptoms of dry eye in Singapore Malay and Indian adults.

    Methods: This was a prospective cross-sectional study. A total of 3303 subjects aged 40 years and above from two large population-based cohorts, the Singapore Malay Eye Study-2 (n = 1191, 2011-2013) and the Singapore Indian Eye Study-2 (n = 2112, 2013-2015), were included. The presence of symptoms of dry eye was defined as having at least one of six symptoms often or all the time. Sleep questionnaires included the Epworth Sleepiness Scale, Berlin Questionnaire, STOP-bang questionnaire, and Insomnia Severity Index. Poor sleep quality was defined as meeting the respective questionnaire thresholds. General health questionnaires (including sleep duration) and standardized ocular and systemic tests were also used.

    Results: Of 3303 participants, 6.4% had excessive sleepiness, 20.5% had high risk for sleep apnea, 2.7% had clinical insomnia, and 7.8% had <5 hours of sleep. These sleep factors were associated with symptoms of dry eye. After adjusting for relevant demographic, medical, and social factors, the following were associated with higher odds of symptoms of dry eye: excessive sleepiness (Epworth Sleepiness Scale: odds ratio [OR] = 1.77 [1.15-2.71]), high risk of sleep apnea (Berlin Questionnaire: OR = 1.55 [1.17-2.07], STOP-Bang Questionnaire: OR = 2.66 [1.53-4.61]), clinical insomnia (Insomnia Severity Index: OR = 3.68 [2.17-6.26]) and <5 hours of sleep (OR = 1.73 [1.17-2.57], reference sleep duration 5-9 hours). Sleep apnea, insomnia, and sleep duration were each shown to be independently associated with symptoms of dry eye.

    Conclusion: Short sleep duration and poor quality are both significantly and independently associated with symptoms of dry eye.

    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology
  11. Wong ML, Sandham A, Ang PK, Wong DC, Tan WC, Huggare J
    Eur J Orthod, 2005 Feb;27(1):91-7.
    PMID: 15743868
    The aim of this study was to measure craniofacial morphology and nasal respiratory resistance (NRR) in Malay, Indian and Chinese subjects with obstructive sleep apnoea (OSA). The sample consisted of 34 male subjects, 27-52 years of age (Malay n = 11, which included five mild and six moderate-severe OSA; Indian n = 11, which included six mild and five moderate-severe OSA; and Chinese n = 12, which included six mild and six moderate-severe OSA) diagnosed using overnight polysomnography. After use of a decongestant, NRR was recorded using anterior and posterior rhinomanometry. Standardized lateral cephalometric radiographs were used to record linear and angular dimensions. Malay subjects with moderate-severe OSA had a shorter maxillary (sp-pm) and mandibular (gn-go) length when compared with a mild OSA reference sample (P < 0.05). The hyoid bone was located more caudally in the Chinese moderate-severe subjects (hy-NL, hy-ML)(P < 0.05), and may be a useful diagnostic indicator for severity in this racial group. No pattern of differences for NRR was seen between the moderate-severe and mild OSA subjects. The consistently lower values for nasopharyngeal resistance in all the moderate-severe subjects when compared with the mild group may indicate that some compensation at this level of the airway had taken place. Strong positive correlations between craniocervical angulation (NL/OPT) and total airway resistance and the turbulent component of flow (k(2)) suggest that head posture is sensitive to fluctuations in airway resistance (P < 0.01).
    Matched MeSH terms: Sleep Apnea, Obstructive/physiopathology
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