Effect of increased lung volume on sleep disordered breathing in patients with sleep apnoea Oral Appliance Therapy versus Nasal Continuous Positive Airway Pressure in Obstructive Sleep Apnea: A Randomized, Placebo-Controlled Trial Eszopiclone increases the respiratory arousal threshold and lowers the apnoea/hypopnoea index in obstructive sleep apnoea patients with a low arousal threshold. The impact of pharyngeal fat tissue on the pathogenesis of obstructive sleep apnea Assessment of the Airway in Obstructive Sleep Apnea Syndrome with 3-Dimensional Airway Computed Tomography Trazodone increases the respiratory arousal threshold in patients with obstructive sleep apnea and a low arousal threshold. Airway assessment by volumetric computed tomography in snorers and subjects with obstructive sleep apnea in a Far-East Asian population (Chinese). Computed tomographic cephalometric analysis of Chinese patients with obstructive sleep apnoea. Change in upper airway geometry between upright and supine position during tidal nasal breathing. Understanding the anatomic basis for obstructive sleep apnea syndrome in adolescents.
Background : Previous studies have shown that changes in lung volume influence upper airway size and resistance , particularly in patients with obstructive sleep apnoea ( OSA ) , and that continuous positive airway pressure ( CPAP ) requirements decrease when the lung volume is increased . We sought to determine the effect of a constant lung volume increase on sleep disordered breathing during non-REM sleep . Methods : Twelve subjects with OSA were studied during non-REM sleep  in a rigid head-out shell equipped with a positive/negative pressure attachment for manipulation of extrathoracic pressure . The increase in lung volume due to CPAP ( at a therapeutic level ) was determined with four magnetometer coils placed on the chest wall and abdomen . CPAP was then stopped and the subjects were studied for 1 hour in three conditions ( in r and om order ) : ( 1 ) no treatment ( baseline ) ; ( 2 ) at “ CPAP lung volume ” , with the increased lung volume being reproduced by negative extrathoracic pressure alone ( lung volume 1 , LV1 ) ; and ( 3 ) 500 ml above the CPAP lung volume(lung volume 2 , LV2 ) . Results : The mean ( SE ) apnoea/hypopnoea index ( AHI ) for baseline , LV1 , and LV2 , respectively , was 62.3 ( 10.2 ) , 37.2 ( 5.0 ) , and 31.2 ( 6.7 ) events per hour ( p = 0.009 ) ; the 3 % oxygen desaturation index was 43.0 ( 10.1 ) , 16.1 ( 5.4 ) , and 12.3 ( 5.3 ) events per hour ( p = 0.002 ) ; and the mean oxygen saturation was 95.4 (0.3)% , 96.0 (0.2)% , 96.3 (0.3)% , respectively ( p = 0.001 ) . Conclusion : An increase in lung volume causes a substantial decrease in sleep disordered breathing in patients with OSA during non-REM sleep Background : Previous r and omized controlled trials have addressed the efficacy of m and ibular advancement devices ( MADs ) in the treatment of obstructive sleep apnea ( OSA ) . Their common control condition , nasal continuous positive airway pressure ( nCPAP ) , was frequently found to be superior to MAD therapy . However , in most of these studies , only nCPAP was titrated objective ly but not MAD . To enable an unbiased comparison between both treatment modalities , the MAD should be titrated objective ly as well . Objective : The aim of the present study was to compare the treatment effects of a titrated MAD with those of nCPAP and an intra-oral placebo device . Methods : Sixty-four mild/moderate patients with obstructive sleep apnea ( OSA ; 52.0 ± 9.6 years ) were r and omly assigned to three parallel groups : MAD , nCPAP and placebo device . From all patients , two polysomnographic recordings were obtained at the hospital : one before treatment and one after approximately 6 months of treatment . Results : The change in the apnea-hypopnea index ( ΔAHI ) between baseline and therapy evaluation differed significantly between the three therapy groups ( ANCOVA ; p = 0.000 ) . No differences in the ΔAHI were found between the MAD and nCPAP therapy ( p = 0.092 ) , whereas the changes in AHI in these groups were significantly larger than those in the placebo group ( p = 0.000 and 0.002 , respectively ) . Conclusion : There is no clinical ly relevant difference between MAD and nCPAP in the treatment of mild/moderate OSA when both treatment modalities are titrated objective ly Recent insights into sleep apnoea pathogenesis reveal that a low respiratory arousal threshold ( awaken easily ) is important for many patients . As most patients experience stable breathing periods mediated by upper-airway dilator muscle activation via accumulation of respiratory stimuli , premature awakening may prevent respiratory stimuli build up as well as the result ing stabilization of sleep and breathing . The aim of the present physiological study was to determine the effects of a non-benzodiazepine sedative , eszopiclone , on the arousal threshold and the AHI ( apnoea/hypopnoea index ) in obstructive sleep apnoea patients . We hypothesized that eszopiclone would increase the arousal threshold and lower the AHI in patients with a low arousal threshold ( 0 to -15 cm H(2)O ) . Following a baseline overnight polysomnogram with an epiglottic pressure catheter to quantify the arousal threshold , 17 obstructive sleep apnoea patients , without major hypoxaemia [ nadir SaO(2 ) ( arterial blood oxygen saturation ) > 70 % ] , returned on two additional nights and received 3 mg of eszopiclone or placebo immediately prior to each study . Compared with placebo , eszopiclone significantly increased the arousal threshold [ -14.0 ( -19.9 to -10.9 ) compared with -18.0 ( -22.2 to -15.1 ) cm H(2)O ; P<0.01 ] , and sleep duration , improved sleep quality and lowered the AHI without respiratory event prolongation or worsening hypoxaemia . Among the eight patients identified as having a low arousal threshold , reductions in the AHI occurred invariably and were most pronounced ( 25±6 compared with 14±4 events/h of sleep ; P<0.01 ) . In conclusion , eszopiclone  increases the arousal threshold and lowers the AHI in obstructive sleep apnoea patients that do not have marked overnight hypoxaemia . The greatest reductions in the AHI occurred in those with a low arousal threshold . The results of this single night physiological study suggest that certain sedatives may be of therapeutic benefit for a definable subgroup of patients . However , additional treatment strategies are probably required to achieve elimination of apnoea Purpose Obesity is the most important risk factor for obstructive sleep apnea ( OSA ) ; however , the exact underlying mechanisms are still not fully understood . The aim of this study was to examine the morphology of upper airways in overweight habitual snorers and in mild OSA patients . Furthermore , the associations between weight loss , parapharyngeal fat pad area and OSA were assessed in a 1-year r and omised , controlled follow-up study originally conducted to determine the effects of lifestyle changes with weight reduction as a treatment of OSA . Methods Thirty-six overweight adult patients with mild OSA [ apnea – hypopnea index ( AHI ) 5–15 events/h ] and 24 weight-matched habitual snorers ( AHI < 5 events/h ) were included in the study . All patients underwent nocturnal cardiorespiratory recordings and multislice computed tomography ( CT ) of parapharyngeal fat pad area , the smallest diameter and area in naso- , oro- and hypopharynx , the smallest diameter and area of the whole pharyngeal airway , the distance from the hyoid bone to the m and ibular plane and to cervical tangent as well as the distance between m and ibular symphysis and cervical spine . In addition , OSA patients were further r and omised to receive either an active 1-year lifestyle intervention with an early weight loss programme or routine lifestyle counselling . After 1 year , the cardiorespiratory recordings and CT scans were repeated . Results The pharyngeal fat pad area was significantly larger , and the distance from the hyoid bone to cervical spine was longer in patients with OSA than in habitual snorers ( p = 0.002 and p = 0.018 , respectively ) . The multiple regression analysis showed that besides a large pharyngeal fat pad area and a long distance from the cervical spine to hyoid bone , also a short distance from the m and ibular symphysis to cervical tangent increased a risk to OSA . During the 1-year follow-up in OSA patients , the pharyngeal fat pad area and AHI decreased significantly in the intervention group ( p = 0.003 and p < 0.001 , respectively ) . Conclusions In the early stages of OSA , the pharyngeal fat pad seems to play an important role in the development of disease in overweight patients . Furthermore , weight reduction by lifestyle intervention-based programme reduces both central obesity and pharyngeal fat pads , result ing in an improvement of OSA OBJECTIVE : The goal was to evaluate 3-dimensional airway CT for upper airway assessment in obstructive sleep apnea syndrome ( OSAS ) . DESIGN : Airway CT was obtained and 3-dimensional airway models were constructed prospect ively for 40 patients with OSAS and 10 controls . Airway dimensions were correlated with polysomnography , and comparison was made between patients with and without OSAS . RESULTS : OSAS patients had a mean respiratory distress index of 51.9 events per hour . The mean minimum cross-sectional area ( XSA ) in the neutral position was 67.1 mm 2 . Minimum XSA decreased in both the inspiratory and expiratory phases to 16.3 mm 2 and 15.0 mm 2 , respectively ( P < 0.001 ) . Complete airway obstruction occurred in 1 or more phases of respiration in 28 patients . Neither airway XSA nor length of obstruction correlated with sleep apnea parameters . No statistically significant differences in airway dimensions were found between OSAS and control patients . CONCLUSIONS : Airway CT demonstrates dynamic airway obstruction in OSAS but does not correlate well with clinical ly important disease parameters . ( Otolaryngol Head Neck Surg 2000;123:444 - 9 . STUDY OBJECTIVES The effect of common sedatives on upper airway physiology and breathing during sleep in obstructive sleep apnea ( OSA ) has been minimally studied . Conceptually , certain sedatives may worsen OSA in some patients . However , sleep and breathing could improve with certain sedatives in patients with OSA with a low respiratory arousal threshold . This study aim ed to test the hypothesis that trazodone increases the respiratory arousal threshold in patients with OSA and a low arousal threshold . Secondary aims were to examine the effects of trazodone on upper airway dilator muscle activity , upper airway collapsibility , and breathing during sleep . DESIGN Patients were studied on 4 separate nights according to a within-subjects cross-over design . SETTING Sleep physiology laboratory . PATIENTS Seven patients with OSA and a low respiratory arousal threshold . INTERVENTIONS In-laboratory polysomnograms were obtained at baseline and after 100 mg of trazodone was administered , followed by detailed overnight physiology experiments under the same conditions . During physiology studies , continuous positive airway pressure was transiently lowered to measure arousal threshold ( negative epiglottic pressure prior to arousal ) , dilator muscle activity ( genioglossus and tensor palatini ) , and upper airway collapsibility ( Pcrit ) . MEASUREMENTS AND RESULTS Trazodone increased the respiratory arousal threshold by 32 ± 6 % ( -11.5 ± 1.4 versus -15.3 ± 2.2 cmH2O , P < 0.01 ) but did not alter the apnea-hypopnea index ( 39 ± 12 versus 39 ± 11 events/h sleep , P = 0.94 ) . Dilator muscle activity and Pcrit also did not systematic ally change with trazodone . CONCLUSIONS Trazodone increases the respiratory arousal threshold in patients with obstructive sleep apnea and a low arousal threshold without major impairment in dilator muscle activity or upper airway collapsibility . However , the magnitude of change in arousal threshold was insufficient to overcome the compromised upper airway anatomy in these patients OBJECTIVES To evaluate the airway dimension of simple snorers and subjects with obstructive sleep apnea ( OSA ) in a Far-East Asian population ( Chinese ) . STUDY DESIGN Prospect i ve study of 117 near-consecutive patients evaluated for snoring and possible OSA from January 1998 to December 1998 in a sleep laboratory .  Overnight polysomnography ( PSG ) was performed on all patients and the sleep parameters , including respiratory disturbance index ( RDI ) , snoring index , minimal oxygen saturation ( min O2 ) , percentage of slow wave sleep ( SWS ) , and rapid eye movement ( REM ) were recorded . Three-dimensional computerized tomography ( CT ) during awake periods was performed . The anteroposterior ( AP ) and the lateral distance of the retropalatal ( RP ) region in the oropharynx , the smallest area of RP , and retroglossal ( RG ) regions , and the total volume of the oropharynx were measured . RESULT Ninety-eight patients were diagnosed with OSA ( mean RDI , 41.48 + /- 26.45 events per hour ; min O2 , 72.82 + /- 12.86 % ) , whereas 19 were simple snorers . The AP and the lateral distance of the RP region , as well as the smallest area of the RP region , are significantly smaller in subjects with OSA . However , no differences in the RG region and the total volume of the oropharynx were found between the two groups . Linear regression analysis demonstrated that the lateral dimension and the smallest RP area in overweight subjects inversely correlated with the RDI , but only the AP dimension of the RP area was found to have an inverse correlation with the RDI in the underweight subjects . CONCLUSION In Far-East Asians ( Chinese ) , the RP airway was found to be the primary site of narrowing in subjects with OSA , and the narrowest RP area was inversely correlated with RDI . Furthermore , weight may influence the pattern of RP narrowing by contributing to lateral collapse Variations of craniofacial and upper airway structures are recognized to contribute to the phenomenon of obstructive sleep apnoea ( OSA ) . Most previous cephalometric studies were performed using erect lateral radiographs in Caucasian patients . The present project aims to determine cephalometric measurements , utilizing CT , in normal Chinese subjects and in Chinese patients with OSA .  Computed tomography of 25 patients with OSA ( proven using overnight polysomnography ) , and of 25 age- , sex- , height- , bodyweight- and body mass index ( BMI ) -matched control subjects were prospect ively performed . Thirteen st and ard bony and soft-tissue measurements were obtained from the CT lateral scout view of the head and neck , taken with each subject in the neutral supine position . The cross-sectional area was calculated at two axial levels ( velopharynx and hypopharynx ) . The measurements in the two groups , OSA and control subjects , were compared . The measurements for hyoid position ( P = 0.00 ) , nasal cavity length ( P = 0.01 ) , m and ibular prognathism ( P = 0.05 ) , tongue size ( P = 0.02 ) , oropharyngeal airway space ( P = 0.02 ) , posterior tongue airway space ( P = 0.04 ) and cross-sectional areas at the level of the velopharynx ( P = 0.00 ) and hypopharynx ( P = 0.01 ) differed significantly between the two groups . In conclusion , CT cephalometric measurements show that certain anatomical variations in the head and neck are likely to contribute to the pathogenesis of OSA in Chinese patients BACKGROUND As the upper airway is the most important limiting factor for the deposition of inhalation medication in the lower airways , it is interesting to assess how its morphology varies between different postures . The goal of this study is to compare the upper airway morphology and functionality of healthy volunteers in the upright and supine positions during tidal nasal breathing and to search for baseline indicators for these changes . This is done by performing three-dimensional measurements on computed tomography ( CT ) and cone beam computed tomography ( CBCT ) scans . METHODS This prospect i ve study was approved by all relevant institutional review boards . All patients gave their signed informed consent . In this study , 20 healthy volunteers ( mean age , 62 years ; age range , 37 - 78 years ; mean body mass index , 29.26 ; body mass index range , 21.63 - 42.17 ; 16 men , 4 women ) underwent a supine low-dose CT scan and an upright CBCT scan of the upper airway . The ( local ) average ( Savg ) and minimal ( Smin ) cross-sectional area , the position of the latter , the concavity , and the airway resistance were examined to determine if they changed from the upright to the supine position . If changes were found , baseline parameters were sought that were indicators for these differences . RESULTS There were five dropouts due to movement artifacts in the CBCT scans . Savg and Smin were 9.76 % and 26.90 % larger , respectively , in the CBCT scan than in the CT scan , whereas the resistance decreased by 26.15 % in the upright position . The Savg of the region between the hard palate and the bottom of the uvula increased the most ( 49.85 % ) . In people with a high body mass index , this value changed the least . The airway resistance in men decreased more than in women . CONCLUSIONS This study demonstrated that there are differences in upper airway morphology and functionality between the supine and upright positions and that there are baseline indicators for these differences RATIONALE Structural risk factors for obstructive sleep apnea syndrome ( OSAS ) in adolescents have not been well characterized . Because many adolescents with OSAS are obese , we hypothesized that the anatomic OSAS risk factors would be more similar to those in adults than those in children . OBJECTIVES To investigate the anatomic risk factors in adolescents with OSAS compared with obese and lean control subjects using magnetic resonance imaging ( MRI ) . METHODS Three groups of adolescents ( age range : 12 - 16 yr ) underwent MRI : obese individuals with OSAS ( n = 49 ) , obese control subjects ( n = 38 ) , and lean control subjects ( n = 50 ) . MEASUREMENTS AND MAIN RESULTS We studied 137 subjects and found that ( 1 ) obese adolescents with OSAS had increased adenotonsillar tissue compared with obese and lean control subjects ; ( 2 ) obese OSAS adolescents had a smaller nasopharyngeal airway than control subjects ; ( 3 ) the size of other upper airway soft tissue structures ( volume of the tongue , parapharyngeal fat pads , lateral walls , and soft palate ) was similar between subjects with OSAS and obese control subjects ; ( 4 ) although there were no major craniofacial abnormalities in most of the adolescents with OSAS , the ratio of soft tissue to craniofacial space surrounding the airway was increased ; and ( 5 ) there were sex differences in the pattern of lymphoid proliferation . CONCLUSIONS Increased size of the pharyngeal lymphoid tissue , rather than enlargement of the upper airway soft tissue structures , is the primary anatomic risk factor for OSAS in obese adolescents . These results are important for clinical decision making and suggest that adenotonsillectomy should be considered as the initial treatment for OSAS in obese adolescents , a group that has poor continuous positive airway pressure adherence and difficulty in achieving weight loss
INTRODUCTION The pathogenesis of upper airway collapse in people with obstructive sleep apnea ( OSA ) is not fully understood .
The aim of this study was to systematic ally review the literature in order to assess the most relevant anatomical characteristics of the upper airway related to the pathogenesis of OSA by analyzing the three-dimensional upper airway anatomy .