Upper airway and soft tissue structural changes induced by CPAP in normal subjects

Oronasal vs Nasal Masks: The Impact of Mask Type on CPAP Requirement, Pharyngeal Critical Closing Pressure (Pcrit), and Upper Airway Cross-Sectional Areas in Patients With OSA

BACKGROUND

CPAP delivered via an oronasal mask is associated with lower adherence, higher residual apnea-hypopnea index (AHI), and increased CPAP therapeutic pressure compared with nasal masks. However, the mechanisms underlying the increased pressure requirements are not well understood.

RESEARCH QUESTION

How do oronasal masks affect upper airway anatomy and collapsibility?

STUDY DESIGN AND METHODS

Fourteen patients with OSA underwent a sleep study with both a nasal and oronasal mask, each for one-half of the night (order randomized). CPAP was manually titrated to determine therapeutic pressure. Upper airway collapsibility was assessed using the pharyngeal critical closing pressure (Pcrit) technique. Cine MRI was done to dynamically assess the cross-sectional area of the retroglossal and retropalatal airway throughout the respiratory cycle with each mask interface. Scans were repeated at 4 cm H2O and at the nasal and oronasal therapeutic pressures.

RESULTS

The oronasal mask was associated with higher therapeutic pressure requirements (ΔM ± SEM; +2.6 ± 0.5; P < .001) and higher Pcrit (+2.4 ± 0.5 cm H2O; P = .001) compared with the nasal mask. The change in therapeutic pressure between masks was strongly correlated with the change in Pcrit (r2 = 0.73; P = .003). Increasing CPAP increased both the retroglossal and retropalatal airway dimensions across both masks. After controlling for pressure and breath phase, the retropalatal cross-sectional area was moderately larger when using a nasal vs an oronasal mask (+17.2 mm2; 95% CI, 6.2-28.2, P < .001) while nasal breathing.

INTERPRETATION

Oronasal masks are associated with a more collapsible airway than nasal masks, which likely contributes to the need for a higher therapeutic pressure.

The effect of CPAP on the upper airway and ventilatory flow in patients with obstructive sleep apnea

BACKGROUND

Continuous positive airway pressure (CPAP) is the mainstay of treatment for obstructive sleep apnea (OSA). However, data about its effect on the upper airway, especially the epiglottis, are scarce. The aim of this study was to investigate the changes in upper airway dimensions and inspiratory flow in response to incremental pressure levels.

METHODS

This is a secondary analysis of a prospective clinical trial in which patients with moderate to severe OSA underwent drug-induced sleep endoscopy with simultaneous recordings of flow and mask pressure. CPAP was titrated in small increments. For each pressure level a representative 3-breath segment was selected to determine specific flow features. The corresponding endoscopic footage was reviewed to assess the degree of upper airway collapse in a semi-quantitative manner.

RESULTS

A total of 214 breath segments were obtained from 13 participants (median [Q1-Q3]; apnea-hypopnea index, 24.9 [20.1-43.9] events/h; body mass index 28.1 [25.1-31.7] kg/m²). CPAP significantly increased cross-sectional dimensions of the soft palate, lateral walls and tongue base, but not of the epiglottis, and induced epiglottis collapse in one subject. Increased pressure improved peak inspiratory flow and median ventilation in all patients, even in the presence of persistent epiglottis collapse.

CONCLUSION

CPAP does not effectively address epiglottis collapse in patients with OSA. However, it normalizes inspiratory flow regardless of its effect on the epiglottis. This clinical trial was registered on January 18th, 2020 on ClinicalTrials.gov with identifier NCT04232410.

Impact of occlusal reconstruction positions on airway dimensions in patients with edentulism and long centric occlusion

OBJECTIVE

To study the airway changes of edentulous patients with a magnitude of long centric (MLC) ≥ 1.5 mm during occlusal reconstruction at the centric relation position (CRP) and muscular position (MP).

METHODS

The CRP and MP were determined by Gothic arch. The cephalometric analysis was taken at the two occlusal positions. The sagittal distance of each part of the upper airway was measured. The differences between two occlusal positions were compared. The difference values were calculated by subtracting the two. The correlation between the MLC and the difference value was analyzed.

RESULTS

The sagittal diameters of palatopharynx and glossopharynx airway at MP were statistically larger than those at CRP (P < 0.05). The MLC had a strong correlation with the ANB angle (r = 0.745, P < 0.001).

CONCLUSION

Compared with the occlusal position of CRP, occlusion reconstruction at MP can provide better airway condition for edentulous patients with large MLC.

Pharyngeal Inflammation on Positron Emission Tomography/Magnetic Resonance Imaging Before and After Obstructive Sleep Apnea Treatment

Rationale: There is upper airway inflammation in patients with obstructive sleep apnea (OSA), which reduces with continuous positive airway pressure (CPAP) therapy. Objectives: Validate the use of positron emission tomography (PET)/magnetic resonance imaging (MRI) to quantify metabolic activity within the pharyngeal mucosa of patients with OSA against nasal lavage proteomics and assess the impact of CPAP therapy. Methods: Adults with OSA underwent [18F]-Fluoro-2-deoxy-D-glucose PET/MRI of the neck before and 3 months after initiating CPAP. Nasal lavage samples were collected. Inflammatory protein expression from samples was analyzed using the Olink platform. Upper airway imaging segmentation was performed. Target-to-background ratio (TBRmax) was calculated from target pharyngeal maximum standard uptake values (SUV) and personalized background mean SUV. Most-diseased segment TBRmax was identified per participant at locations with the highest PET avidity. Correlation analysis was performed between baseline TBRmax and nasal lavage proteomics. TBRmax was compared before and after CPAP using linear mixed-effect models. Results: Among 38 participants, the baseline mean age was 46.3 years (standard deviation [SD], 12.5), 21% were female, the mean body mass index was 30.9 kg/m2 (SD, 4.6), and the mean respiratory disturbance index measured by peripheral arterial tonometry was 31 events/h (SD, 16.4). There was a significant positive correlation between pharyngeal mucosa most-diseased segment TBRmax and nasal lavage proteomic inflammation (r = 0.41 [P < 0.001, false discovery rate = 0.002]). Primary analysis revealed a reduction in the most-diseased segment TBRmax after a median of 2.91 months of CPAP therapy (-0.86 [standard error (SE) ± 0.30; P = 0.007]). Stratified analysis by smoking status revealed a significantly decreased most-diseased segment TBRmax after CPAP therapy among never-smokers but not among ever-smokers (-1.01 [SE ± 0.39; P = 0.015] vs. -0.64 [SE ± 0.49; P = 0.201]). Conclusions: CPAP therapy reduces metabolic activity measured by PET/MRI within the upper airway of adults with OSA. Furthermore, PET/MRI measures of upper airway metabolic activity correlate with a noninvasive marker of inflammation (i.e., nasal lavage inflammatory protein expression).

The Effects of Anterior Palatoplasty and Functional Expansion Sphincter Pharyngoplasty on Voice Quality in Patients with Obstructive Sleep Apnea

OBJECTIVES

We aimed to examine the effects of anterior palatoplasty (AP) and functional expansion sphincter pharyngoplasty (FESP) on voice quality in patients with OSAS and to compare them with each other.

MERHODS

The study included 380 patients who came to the Otorhinolaryngology Clinic of our hospital with symptoms of snoring and sleep apnea between April 2020 and April 2022 and were referred to the sleep laboratory for polysomnography (PSG).Forty patients who met the study criteria and underwent AP and 26 patients who underwent FESP were included in the study. All surgeries were performed under general anesthesia by the same otolaryngologist within 1 month at the latest after sleep endoscopy. Acoustic voice analysis was performed using the Praat voice analysis program preoperatively and postoperatively at 6 months. F0, jitter, shimmer, and NHR (noise-to-harmonic ratio) were compared between the groups pre and postoperatively.

RESULTS

There were 20 females and 20 males in the AP group, 12 females and 14 males in the FESP group, There was no statistically significant difference in sex distribution between the groups (P = 0.952). The difference between the preop and postop F0, jitter, shimmer, and NHR in both the AP and FESP groups was statistically significant (P < 0.01). After AP and FESP surgeries, F0 values ​​increased, jitter, shimmer and NHR values ​​decreased (P < 0.01).F0, jitter, shimmer, and NHR changes were the greatest in the FESP group.(P < 0.01).

CONCLUSION

Positive changes in F0, jitter, shimmer, and NHR were greatest in the FESP group significantly. FESP surgery affects voice quality more than AP surgery in patients with OSAS.

Sleep Endoscopy with Positive Airway Pressure: A Method for Better Compliance and Individualized Treatment of Patients with Obstructive Sleep Apnea

In this study, we aimed to observe the effects of positive airway pressure (PAP) on individual levels of obstruction during drug-induced sleep endoscopy (DISE) of the upper airways (UA), to evaluate at which pressures the obstruction disappeared or worsened, and to identify cases in which PAP was ineffective. This prospective study was conducted from June 2018 to June 2022. PAP testing was performed during DISE in patients with moderate and severe OSA. The pressure was gradually increased over the range from 6.0 to 18.0 hPa. Our findings were evaluated using the VOTE classification. The examination was performed in 56 patients, with a median apnea-hypopnea index (AHI) of 26.4. Complete obstruction of the soft palate was observed in 51/56 patients (91%), oropharyngeal obstruction in 15/56 patients (27%), tongue base obstruction in 23/56 patients (41%), and epiglottic collapse in 16/56 patients (29%). PAP was most effective in cases of complete oropharyngeal obstruction, and least effective in cases of epiglottic collapse, where it was ineffective in 11/16 patients. DISE with PAP is a simple diagnostic method that can be helpful for identifying anatomic and dynamic reasons for PAP intolerance. The main indication is ineffective PAP treatment.

Continuous Positive Airway Pressure Titration During Pediatric Drug Induced Sleep Endoscopy

OBJECTIVE

To observe the degree of airway collapse at varying levels of continuous positive airway pressure (CPAP) during drug pediatric induced sleep endoscopy.

METHODS

Using our institutional anesthesia protocol for pediatric DISE procedures, patients were anesthetized followed by evaluation of the nasal airway, nasopharynx, velum, hypopharynx, arytenoids, tongue base, and epiglottis. CPAP titration was performed under vision to evaluate the degree of airway collapse at the level of the velum. Comparison was made with pre-operative polysomnography findings.

RESULTS

Twelve pediatric patients underwent DISE with intraoperative CPAP titration. In 7/12 patients, DISE observed CPAP titration was beneficial in elucidating areas of obstruction that were observed at pressures beyond those recommended during preoperative sleep study titrations. In 3 patients, DISE observations provided a basis for evaluation in children not compliant with sleep study CPAP titration testing. With regard to regions effected, airway collapse was observed at the velum and oropharynx to a greater degree when compared with the tongue base and epiglottis.

CONCLUSION

DISE evaluation of the pediatric patient with obstructive sleep apnea may present a source for further patient evaluation with respect to CPAP optimization and severity of OSA assessment, particularly in syndromic patients.

Reversibility of retinochoroidal vascular alteration in patients with obstructive sleep apnea after continuous positive air pressure and surgical intervention

Purpose

The aim of this work was to study various retinochoroidal parameters in patients with obstructive sleep apnea syndrome (OSAS) and the effect of interventions on these parameters at 6 months follow-up.

Methods

A total of 36 patients were recruited prospectively from the otorhinolaryngology clinics of a large tertiary center between September 2018 to March 2020. The subjects were divided into three groups depending upon intervention chosen for OSAS: Group A (surgery, i.e., uvulopalatopharyngoplasty), group B (medical therapy, i.e., continuous positive air pressure) and group C (no intervention). Various retinochoroidal parameters which were studied included retinal thickness (RT), choroidal thickness (CT), choroidal vascularity index (CVI), arteriovenous ratio (AVR), capillary density index (CDI) in superficial and deep retina, at baseline and 6 months of follow-up after the intervention.

Results

In group A, CT increased significantly at 6 months (332.76 ± 86.41 um) compared to baseline (306.28 ± 78.19) (P = 0.0004). Similarly, CDI at both superficial and deep capillary plexus increased significantly at 6 months (superficial CDI: 0.65 ± 0.04, deep CDI: 0.38 ± 0.01) compared to baseline (superficial CDI: 0.62 ± 0.03, deep CDI: 0.36 ± 0.02) (P = 0.004 and 0.002 respectively). In group B, CT increased significantly at 6 months (361.38 ± 78.63 um) compared to baseline (324.21 ± 76.97 um) (P = 0.008). Also, CVI showed a significant decrease at 6 months (65.74 ± 1.84%) compared to baseline (67.36 ± 1.57%) (P = 0.019). In group C, all except CDI in deep capillary plexus showed a significant decrease at 6 months (0.35 ± 0.01) compared to baseline (0.36 ± 0.02) (P = 0.003).

Conclusion

OSAS alters various retinochoroidal parameters and timely intervention in patients with OSAS can prevent these alterations. Also, these retinochoroidal parameters could serve as one of the markers to monitor the disease progression.

Can drug-induced sleep endoscopy (DISE) predict compliance with positive airway pressure therapy? A pilot study

PURPOSE

Drug-induced sleep endoscopy (DISE) has been poorly explored as an examination to assess positive airway pressure (PAP) therapy in patients with obstructive sleep apnea (OSA). The present study aimed to identify by DISE possible characteristics related to low compliance with PAP therapy due to respiratory complaints.

METHODS

Patients using PAP for OSA underwent DISE in two conditions: (1) baseline (without PAP) and (2) PAP (with the same mask and airway pressure used at home). We compared patients reporting low compliance to PAP due to respiratory complaints to those well-adapted to therapy. VOTE classification (assessment of velopharynx, oropharynx, tongue base, and epiglottis) and TOTAL VOTE score (the sum of VOTE scores at each anatomical site) were assessed. ROC curve analyzed the accuracy of TOTAL VOTE to predict low compliance due to persistent pharyngeal obstruction in both conditions.

RESULTS

Of 19 patients enrolled, all presented multilevel pharyngeal obstruction at baseline condition, with no difference between groups at this study point. When PAP was added, the median VOTE value was higher in the epiglottis (P value=0.02) and tended to be higher at the velum and tongue base in the poorly adapted group; TOTAL VOTE score was also significantly increased in patients with low compliance (P value<0.001). ROC curve demonstrated that patients with TOTAL VOTE scored 2.5 or more during DISE with PAP presented a 4.6-fold higher risk for low compliance with PAP therapy due to pharyngeal obstruction (AUC: 0.88±0.07; P value<0.01; sensitivity: 77%; specificity: 83%).

CONCLUSIONS

Adding PAP during a DISE examination may help to predict persistent pharyngeal obstruction during PAP therapy.

Effect of body weight on upper airway findings and treatment outcome in children with obstructive sleep apnea

OBJECTIVE/BACKGROUND

Surgical interventions for obstructive sleep apnea (OSA) are less effective in obese than in normal-weight children. However, the mechanisms that underpin this relationship are not fully understood. Therefore, this study aimed to explore how body weight influences upper airway collapse and treatment outcome in children with OSA.

METHODS

We conducted a retrospective analysis of prospectively collected data on polysomnography, drug-induced sleep endoscopy (DISE), and treatment outcome in otherwise healthy children with OSA. Associations between body mass index (BMI) z-score and upper airway collapse during DISE were assessed using logistic regression modelling. Treatment success was defined as obstructive apnea-hypopnea index (oAHI) < 5 events/hour and cure as oAHI < 2 events/hour with obstructive apnea index < 1 event/hour.

RESULTS

A total of 139 children were included [median (Q1─Q3); age 4.5 (3.1─8.4) years; BMI z-score 0.3 (-0.8 to 1.4); oAHI 10.8 (6.8─18.0) events/hour]. Twenty-five of them were overweight and 21 were obese. After adjusting for age and history of upper airway surgery, BMI z-score was significantly correlated with circumferential upper airway collapse during DISE (odds ratio 1.67; 95% confidence interval 1.12─2.65; P = 0.011). Outcome of DISE-directed treatment was similar in normal-weight (success: 91.4%; cure: 78.5%), overweight (success: 88.0%; cure: 80.0%), and obese (success: 90.5%; cure: 76.5%) children. Children with circumferential collapse responded better to continuous positive airway pressure than to (adeno)tonsillectomy.

CONCLUSION

Increasing body weight is associated with circumferential upper airway collapse during DISE and, accordingly, may require treatment strategies other than (adeno)tonsillectomy.

Evaluation of the effects of helmet continuous positive airway pressure on laryngeal size in dogs anesthetized with propofol and fentanyl using computed tomography

OBJECTIVE

To evaluate the effect of 5 cm H₂ O of continuous positive airway pressure (CPAP) on laryngeal size in spontaneously breathing anesthetized dogs via computed tomography (CT).

DESIGN

Prospective, randomized, cross-over clinical study.

SETTING

University teaching hospital and referral private practice.

ANIMALS

Eight healthy client-owned dogs undergoing CT.

INTERVENTIONS

Dogs were sedated with acepromazine 20 μg/kg IM and induced with fentanyl 2 μg/kg and propofol 3-5 mg/kg IV before being maintained on fentanyl (5 μg/kg/h) and propofol (0.3 mg/kg/min) constant rate infusion. Dogs received an air/oxygen mixture with (CPAP) and without (NO-CPAP) 5 cm H₂ O of CPAP in a random order. Each study step lasted 15 minutes.

MEASUREMENTS AND MAIN RESULTS

Ten minutes after the beginning of each study period, a CT scan of the laryngeal region was obtained at end-expiration. CT images were analyzed to determine the laryngeal cross-sectional area (CSA; cm² ), total volume (V_TOT ; cm³ ), and laterolateral and dorsoventral diameters (D_LL and D_DV , respectively; cm). Differences between the 2 treatments were analyzed with t-test for paired data (P < 0.05). Compared to the NO-CPAP, during CPAP the CSA increased by 53.3 ± 23.1% (ie, from 3.3 ± 0.8 to 5.1 ± 1.3 cm² , P = 0.0004), V_TOT increased by 52.4 ± 13.6% (from 6.2 ± 1.7 to 9.4 ± 2.4 cm³ , P < 0.0001), and D_LL and D_DV were 55.5 ± 13.3% (3.6 ± 0.8 vs 2.4 ± 0.5 cm, P = 0.006) and 20.3 ± 8.8% larger (3.2 ± 0.7 vs 2.7 ± 0.6 cm, P = 0.0002), respectively.

CONCLUSIONS

Laryngeal volume and cross sectional area increased during the application of 5 cm H₂ O of helmet CPAP in spontaneously breathing anesthetized dogs.

Drug-induced sleep endoscopy while administering CPAP therapy in patients with CPAP failure

Study objectives

To study the pattern of upper airway collapse in patients with CPAP failure by performing DISE while administering CPAP therapy and to determine the reason for CPAP failure accordingly.

Methods

This observational retrospective study comprised 30 patients diagnosed with OSA and CPAP failure, who underwent DISE while administering CPAP therapy. During DISE, the upper airway was assessed with and without CPAP therapy using the VOTE classification. Additionally, a jaw thrust maneuver was performed, in order to mimic the effect of an additional mandibular advancement device (MAD) in combination with CPAP therapy. Consequently, the outcome of DISE was translated into a clinically relevant categorization.

Results

Eleven patients (37%) had a persistent anteroposterior (AP) collapse, including a collapse at velum, tongue base, or epiglottis level and multilevel collapse. Eight patients (27%) had a floppy epiglottis. Five patients (17%) had a persistent complete concentric collapse (CCC) and three patients had a persistent laryngeal collapse (10%). In three patients (10%), no airway collapse was found after CPAP administration.

Conclusions

Based on the results of the reported study, in most cases, the potential cause of CPAP failure can be determined by this new diagnostic method. Consequently, suggestions can be made for additional therapy.

Long-Term Objective Adherence to Mandibular Advancement Device Therapy Versus Continuous Positive Airway Pressure in Patients With Moderate Obstructive Sleep Apnea

STUDY OBJECTIVES

Comparable health effects of mandibular advancement device (MAD) and continuous positive airway pressure (CPAP) therapy have been attributed to higher adherence with MAD compared with CPAP therapy. The objective of this study was to make a direct comparison of the objective adherence between MAD and CPAP in patients with moderate obstructive sleep apnea (OSA).

METHODS

Adherence was monitored for 12 months in 59 patients with moderate OSA (apnea-hypopnea index 15-30 events/h) as part of a randomized controlled trial. Objective adherence with MAD was assessed using the TheraMon microsensor. Objective adherence with CPAP was assessed using the built-in registration software with readout on SD card. Self-reported adherence with both therapies was assessed using a questionnaire.

RESULTS

Forty patients (68%) completed the study with the therapy to which they were randomly assigned. Median (interquartile range) objective adherence (h/night) in the 3rd month was 7.4 (5.2-8.2) for MAD and 6.8 (5.7-7.6) for CPAP (P = .41), compared to 6.9 (3.5-7.9) with MAD and 6.8 (5.2-7.6) with CPAP (P = .85) in the 12th month. There were no significant changes between the 3rd and 12th month for both MAD (P = .21) and CPAP (P = .46). Changes in adherence were not significantly different between MAD and CPAP (P = .51). Self-reported adherence was significantly higher with MAD than CPAP at all follow-ups. Self-reported adherence with CPAP was lower than objective CPAP adherence at the 6th and 12th month (P = .02).

CONCLUSIONS

Objective adherence with MAD and CPAP is comparable and consistent over time. Self-reported adherence is higher with MAD than with CPAP giving rise to interesting discrepancy between objective and self-reported adherence with CPAP.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Identifier: NCT01588275.

Heritability of the pharyngeal airway volume and dimensions as assessed from siblings with overt malocclusions

OBJECTIVE

To quantify the relative contributions of genetic and environmental factors to airway volume and dimensions in orthodontic patients.

MATERIALS AND METHODS

One hundred and twenty-five siblings from 57 families were selected. Cone beam computed tomography scans were taken as part of the orthodontic records and the Dolphin3D © imaging software was used to determine airway volume and dimensions. SOLAR program was implemented to calculate heritability.

RESULTS

The heritability of the airway volume was negligible but increased significantly from 5% to 72% (95% confidence interval was 27% to 100%) when anterior-posterior (AP) dimension was controlled in the calculating model.

CONCLUSION

The capacity to maintain, rather than having proper AP dimension of the airway, seems to be the most critical mark of a proper airway volume.

State-dependent changes in the upper airway assessed by multidetector CT in healthy individuals and during obstructive events in patients with sleep apnea

Objective:

To determine whether airway narrowing during obstructive events occurs predominantly at the retropalatal level and results from dynamic changes in the lateral pharyngeal walls and in tongue position.

Methods:

We evaluated 11 patients with severe obstructive sleep apnea (OSA) and 7 healthy controls without OSA during wakefulness and during natural sleep (documented by full polysomnography). Using fast multidetector CT, we obtained images of the upper airway in the waking and sleep states.

Results:

Upper airway narrowing during sleep was significantly greater at the retropalatal level than at the retroglossal level in the OSA group (p < 0.001) and in the control group (p < 0.05). The retropalatal airway volume was smaller in the OSA group than in the control group during wakefulness (p < 0.05) and decreased significantly from wakefulness to sleep only among the OSA group subjects. Retropalatal pharyngeal narrowing was attributed to reductions in the anteroposterior diameter (p = 0.001) and lateral diameter (p = 0.006), which correlated with an increase in lateral pharyngeal wall volume (p = 0.001) and posterior displacement of the tongue (p = 0.001), respectively. Retroglossal pharyngeal narrowing during sleep did not occur in the OSA group subjects.

Conclusions:

In patients with OSA, upper airway narrowing during sleep occurs predominantly at the retropalatal level, affecting the anteroposterior and lateral dimensions, being associated with lateral pharyngeal wall enlargement and posterior tongue displacement.

Barbed suspension pharyngoplasty for treatment of lateral pharyngeal wall and palatal collapse in patients affected by OSAHS

PURPOSE

The aim of this study is to analyze the efficacy of a new modified pharyngoplasty technique with barbed sutures: barbed suspension pharyngoplasty (BSP).

METHODS

We enrolled patients affected by obstructive sleep apnea-hypopnea syndrome (OSAHS), having the main site of obstruction at the palatal and lateral pharyngeal walls, who refused or failed to tolerate CPAP therapy and underwent non-resective pharyngoplasty with barbed sutures between January 2014 and October 2017. Two surgical techniques with barbed sutures were used: barbed reposition pharyngoplasty (BRP) and BSP; the main characteristics of the latter are a double passage of the needle, each side, through the soft palate.

RESULTS

Forty-two patients met the study inclusion criteria and were included in the analysis. Twenty-two patients underwent BRP and 20 BSP. Patients treated with both BRP and BSP achieved significant improvement in polysomnographic parameters: AHI, ODI, t90%, and daily sleepiness tested by the ESS questionnaire (p < 0.001). There were no significant differences between groups considering gender, age, or severity of OSAHS (p > 0.05). Outcomes were also comparable (p = 0.10) in the two groups; patients who underwent BSP had successful treatment in 100% of cases, compared to 86% with BRP, with a cure rate of 40% vs. 18%.

CONCLUSIONS

BSP is a novel surgical technique that is effective in treating oropharyngeal collapse and can be tailored for patients with high collapsibility of the soft palate who might benefit from the palatal stiffness given by multiple passages of the suture inside it.

Sleep and Nocturnal Gastroesophageal Reflux: An Update

Nocturnal gastroesophageal reflux has been associated with poor sleep quality. Normal physiological adaptations of the aerodigestive system to sleep prolong and intensify nocturnal reflux events. This occurrence leads to sleep disruption, as well as to esophageal, laryngeal, and laryngopharyngeal reflux. Controversy exists on whether OSA and nocturnal reflux are causally linked or merely associated because of shared risk factors. Advances in diagnostic technology have provided new insights into gastroesophageal reflux and the mechanisms of nocturnal reflux during sleep. This update reviews new data on causal links between sleep and gastroesophageal reflux disease.

Cardiorespiratory interaction with continuous positive airway pressure

The treatment of choice for obstructive sleep apnoea (OSA) is continuous positive airway pressure therapy (CPAP). Since its introduction in clinical practice, CPAP has been used in various clinical conditions with variable and heterogeneous outcomes. In addition to the well-known effects on the upper airway CPAP impacts on intrathoracic pressures, haemodynamics and blood pressure (BP) control. However, short- and long-term effects of CPAP therapy depend on multiple variables which include symptoms, underlying condition, pressure used, treatment acceptance, compliance and usage. CPAP can alter long-term cardiovascular risk in patients with cardiorespiratory conditions. Furthermore, the effect of CPAP on the awake patient differs from the effect on the patients while asleep, and this might contribute to discomfort and removal of the use interface. The purpose of this review is to highlight the physiological impact of CPAP on the cardiorespiratory system, including short-term benefits and long-term outcomes.

Magnetic resonance imaging of the upper airway in patients with quadriplegia and obstructive sleep apnea

The aim of this study was to investigate upper airway anatomy in quadriplegics with obstructive sleep apnea. Fifty subjects were recruited from three hospitals in Australia: people with quadriplegia due to spinal cord injury and obstructive sleep apnea (n = 11), able-bodied people with obstructive sleep apnea (n = 18), and healthy, able-bodied controls (n = 19). All underwent 3-Tesla magnetic resonance imaging of their upper airway. A subgroup (n = 34) received a topical vasoconstrictor, phenylephrine and post-phenylephrine magnetic resonance imaging. Mixed-model analysis indicated no significant differences in total airway lumen volume between the three groups (P = 0.086). Spinal cord injury-obstructive sleep apnea subjects had a significantly larger volume of soft palate (P = 0.020) and retroglossal lateral pharyngeal walls (P = 0.043) than able-bodied controls. Able-bodied-obstructive sleep apnea subjects had a smaller mandible volume than spinal cord injury-obstructive sleep apnea subjects and able-bodied control subjects (P = 0.036). No differences were seen in airway length between groups when controlling for height (P = 0.055). There was a marginal increase in velopharyngeal volume across groups post-phenylephrine (P = 0.050), and post hoc testing indicated the difference was confined to the able-bodied-obstructive sleep apnea group (P < 0.001). No other upper airway structures showed significant changes with phenylephrine administration. In conclusion, people with obstructive sleep apnea and quadriplegia do not have a structurally smaller airway than able-bodied subjects. They did, however, have greater volumes of soft palate and lateral pharyngeal walls, possibly due to greater neck fat deposition. The acute response to upper airway topical vasoconstriction was not enhanced in those with obstructive sleep apnea and quadriplegia. Changes in upper airway anatomy likely contribute to the high incidence in obstructive sleep apnea in quadriplegic subjects.

Barbed snore surgery for concentric collapse at the velum: The Alianza technique

Recently, new conservative and non-resective surgical techniques, including palatopharyngeal surgical lifting and suspension (the 'Roman blinds technique') and modular barbed snore surgery (MBSS), have been successfully introduced for the treatment of obstructive sleep apnea syndrome (OSAS). This pilot longitudinal study describes our preliminary experience with the 'Alianza technique' (the simultaneous use of Roman blinds and MBSS) in mild to moderate OSAS patients with concentric pharyngeal collapse at the velum, previously documented by means of drug-induced sleep endoscopy. Effectiveness of the surgical procedure was assessed by means of the Epworth sleepiness scale (ESS), overnight polysomnography, and a 0-10 snoring visual analogue scale (VAS); tolerability was assessed by means of a 0-10 pain VAS. The final analysis relating to 19 patients (18 males; 94.8%), with a mean age of 43.8 ± 8.8 years, showed a statistically significant reduction in mean post-operative apnea-hypopnea indexes (22.3 ± 5.1 vs 7.0 ± 9.4 events/hour; p-value = 0.002) and mean ESS scores (11.3 ± 5.4 vs 3.9 ± 4.0; p-value < 0.001). There was also a significant decrease in mean post-operative snoring VAS scores (9.5 ± 0.7 vs 2.1 ± 1.7; p-value < 0.001). Surgery was well tolerated in most patients (mean pain VAS scores on day seven: 2.4 ± 1.4), and there were no major complications. In experienced hands, the Alianza can be considered an effective and safe technique for the treatment of mild to moderate OSAS.

Impact of continuous positive airway pressure in patients with obstructive sleep apnea during drug-induced sleep endoscopy

OBJECTIVES

The primary objective of the study was to understand the differential impact of continuous positive airway pressure (CPAP) on the location, degree and pattern of airway collapse in obstructive sleep apnea (OSA) patients utilizing drug-induced sleep endoscopy (DISE).

STUDY DESIGN

Non-randomized trial.

SETTING

University Medical Center.

PARTICIPANTS

Fifteen consecutive OSA patients undergoing DISE.

MAIN OUTCOMES AND MEASURES

The patterns of airway collapse were videorecorded at baseline and under differential application of nasal CPAP (nCPAP) at 5, 10 and 15 cm H₂ O. For each modality, the pattern and degree of airway collapse were analyzed by three independent observers using the velum, oropharynx, tongue base, epiglottis (VOTE) classification system.

RESULTS

The modest nCPAP pressures (10 cm H₂ O) had the greatest impact on the lateral walls of the pharynx, followed by the palatal region. The collapsibility of the tongue base and epiglottis demonstrated significant resistance to nCPAP application, which was overcome by increasing nCPAP to 15 cm H₂ O. Compared to 5 cm H₂ O, nCPAP pressures of 10 and 15 cm H₂ O improved complete collapse at least at one level of the upper airway (P=.016 and .001, respectively). Increased nCPAP pressures also led to changes in the configuration of airway collapse at the level of the velum.

CONCLUSIONS

The differential nCPAP effects observed in this study may help to understand some of the mechanisms responsible for inadequate patient response and poor nCPAP compliance. The use of DISE in combination with CPAP may serve as a first step in optimizing patients that failed to adapt to treatment with CPAP. This approach can help the physician identify patterns of airway collapse that may require varying pressures different from the one the patient is using, as well as anatomical factors that may be corrected to help with compliance.

Opioid Toxicity

In recent years, there has been a substantial increase in opioid use and abuse, and in opioid-related fatal overdoses. The increase in opioid use has resulted at least in part from individuals transitioning from prescribed opioids to heroin and fentanyl, which can cause significant respiratory depression that can progress to apnea and death. Heroin and fentanyl may be used individually, together, or in combination with other substances such as ethanol, benzodiazepines, or other drugs that can have additional deleterious effects on respiration. Suspicion that a death is drug-related begins with the decedent's medical and social history, and scene investigation, where drugs and drug paraphernalia may be encountered, and examination of the decedent, which may reveal needle punctures and needle track marks. At autopsy, the most significant internal finding that is reflective of opioid toxicity is pulmonary edema and congestion, and frothy watery fluid is often present in the airways. Various medical ailments such as heart and lung disease and obesity may limit an individual's physiologic reserve, rendering them more susceptible to the toxic effects of opioids and other drugs. Although many opioids will be detected on routine toxicology testing, more specialized testing may be warranted for opioid analogs, or other uncommon, synthetic, or semisynthetic drugs.

Submental Ultrasonographic Parameters among Patients with Obstructive Sleep Apnea

Objective

This study aimed to determine the value of submental ultrasonography (US) parameters for diagnostic workup among patients with obstructive sleep apnea (OSA) and to determine whether there is a correlation between US findings and the severity of OSA.

Study Design

Cross-sectional analysis.

Setting

Tertiary education hospital.

Subjects and Methods

The study included 147 patients with suspected OSA who underwent submental US to evaluate various parameters following overnight polysomnography. US findings were compared with the apnea-hypopnea index and other parameters.

Results

All US parameters, except for subcutaneous tissue thickness, were significantly different among patients with OSA. Of note, distance between lingual arteries (DLA), geniohyoid muscle thickness (GMT), and lateral parapharyngeal wall thickness (LPWT) were significantly greater in the patients with severe OSA than those with mild and moderate OSA ( P < .001). GMT had the strongest correlation with OSA ( r = 0.419, P < .001); LPWT and DLA also had high correlation coefficient values ( r = 0.343, P < .001, and r = 0.342, P < .001, respectively). Stepwise regression analysis showed that GMT (beta = 0.243, P = 0.004), LPWT (beta = 0.236, P = 0.004), and DLA (beta = 0.204, P = 0.008) were the most significant factors for predicting the severity of OSA according to the apnea-hypopnea index.

Conclusion

Submental US can be used to determine whether there is a correlation between US findings and severity of OSA. GMT could be considered a novel parameter for determining the severity of OSA.

Cervical computed tomography in patients with obstructive sleep apnea: influence of head elevation on the assessment of upper airway volume

OBJECTIVE

Obstructive sleep apnea syndrome (OSAS) has a high prevalence and carries significant cardiovascular risks. It is important to study new therapeutic approaches to this disease. Positional therapy might be beneficial in reducing the apnea-hypopnea index (AHI). Imaging methods have been employed in order to facilitate the evaluation of the airways of OSAS patients and can be used in order to determine the effectiveness of certain treatments. This study was aimed at determining the influence that upper airway volume, as measured by cervical CT, has in patients diagnosed with OSAS.

METHODS

This was a quantitative, observational, cross-sectional study. We evaluated 10 patients who had been diagnosed with OSAS by polysomnography and on the basis of the clinical evaluation. All of the patients underwent conventional cervical CT in the supine position. Scans were obtained with the head of the patient in two positions (neutral and at a 44° upward inclination), and the upper airway volume was compared between the two.

RESULTS

The mean age, BMI, and neck circumference were 48.9 ± 14.4 years, 30.5 ± 3.5 kg/m2, and 40.3 ± 3.4 cm, respectively. The mean AHI was 13.7 ± 10.6 events/h (range, 6.0-41.6 events/h). The OSAS was classified as mild, moderate, and severe in 70%, 20%, and 10% of the patients, respectively. The mean upper airway volume was 7.9 cm3 greater when the head was at a 44° upward inclination than when it was in the neutral position, and that difference (17.5 ± 11.0%) was statistically significant (p = 0.002).

CONCLUSIONS

Elevating the head appears to result in a significant increase in the caliber of the upper airways in OSAS patients.

The size and behavior of the human upper airway during inhalation of aerosols

INTRODUCTION

The mouth, the pharynx and the larynx are potential sites of aerosol deposition in the upper airway during inhalation of aerosolized drugs. The right angle bend of the lumen at the back of the mouth, the position of the tongue, the variable size and shape of the lumen in the pharynx and the larynx, and the breathing pattern could increase aerosol deposition in the upper airway and decrease lung deposition. Areas covered: In this review, the anatomy of the upper airway from the oral cavity to the glottis and the impact of mandibular protrusion and incisal opening on the size of the upper airway are highlighted. In addition, the impact of inhalation maneuvers, inhaler mouthpiece geometries and a stepped mouthpiece on the size of the upper airway are discussed. Expert opinion: The structure of the upper airway lumen does not have a fixed cross sectional area and is susceptible to both constriction and distension during inhalation. The size of the upper airway can be enlarged through mandibular protrusion and/or incisal opening which might decrease aerosol deposition in the upper airway and increase lung deposition.

Sleep apnea is associated with an increased risk of mood disorders: a population-based cohort study

PURPOSE

The symptoms of sleep apnea, such as sleep fragmentation and oxygen desaturation, might be risk factors for subsequent mood disorder (MD), but associations between sleep apnea and MD remain unclear. This nationwide population-based study thus aimed to identify the risk of MD in patients with vs. without sleep apnea.

METHODS

This cohort study used data from the National Health Insurance database. In total, 5415 patients diagnosed with sleep apnea between 2000 and 2010 were evaluated, and 27,075 matched non-sleep apnea enrollees were included as a comparison cohort. All subjects were followed until 2011. The Cox proportional hazard ratio (HR) was used to investigate the relationship between MD and sleep apnea while controlling covariates and comorbidities of sleep apnea.

RESULTS

Of 5415, 154 patients with sleep apnea (2.84 %) were diagnosed with MD during the follow-up period in comparison with 306 of 27,075 individuals (1.13 %) without antecedent sleep apnea. After adjusting for the selected factors and comorbidities, we found that patients with sleep apnea were from 1.82- to 2.07-fold greater risk of MD than the comparisons. Of the three subcategories of MD (major depressive disorder, bipolar disorder, and unspecified MD), sleep apnea had the highest predisposing risk with respect to major depressive disorder (adjusted HR from 1.82 to 2.07) and bipolar disorder (adjusted HR from 2.15 to 3.24).

CONCLUSIONS

There is a greater likelihood of MD manifesting in patients with a history of sleep apnea. Health professionals are thus advised to carefully monitor the psychological impacts of sleep apnea.

Upper airway structural changes induced by CPAP in OSAS patients: a study using drug-induced sleep endoscopy

We studied upper airway structural changes induced by continuous positive airway pressure (CPAP) in obstructive sleep apnea syndrome (OSAS) patients using drug-induced sleep endoscopy (DISE). This prospective study was conducted at an academic secondary referral center. In total, 28 male OSAS patients (mean age 41.1 years) with only retropalatal level obstructions were enrolled. Measurements of the obstruction site were obtained in two steps: first a measurement was taken of the obstruction site in accordance with sleep apnea, then, a measurement was taken of the obstruction site in accordance with DISE-assisted CPAP titration, including quantitative changes in the occlusion site before and after CPAP in pixel format using an area calculation program. There was a tendency for persistent closing in cases of antero-posterior (AP) obstruction versus cases of lateral (Lat) obstruction in the CPAP titration. Lat obstructions showed a tendency to be wider than AP obstructions in the quantitative analysis. These results show that the pattern and degree of airway expansion after CPAP differ in accordance with the obstruction site.

A novel implantable device for a minimally invasive surgical treatment of obstructive sleep apnea: design and preclinical safety assessment

BACKGROUND

In obstructive sleep apnea (OSA), occlusion of the upper airway by soft tissue causes intermittent hypoxemia and can have serious sequelae. A novel implantable medical device for OSA is composed of a linear silicone elastic element held in an extended state by a bioabsorbable external sheath. The implant is delivered to the tongue base or soft palate via a minimally invasive approach. Normal tissue healing anchors the device at the attachment points before the bioabsorbable material dissolves and the elastic element contracts to stabilize the surrounding tissue.

METHODS

Device prototypes were evaluated in multiple investigations: 1) a finite elements analysis model simulated the movement of the tongue base during sleep with and without the implant; 2) dynamic mechanical testing simulated 10 years' normal use; 3) cadaveric implantations were conducted; 4) an ovine study in which implants of varying design were evaluated via gross pathology and histological assessment; and 5) a canine study in which implants of varying design in the tongue base and soft palate were evaluated via gross pathology and histological assessment.

RESULTS

1) The implant was capable of reducing ~95% of tongue base movement during simulated sleep; 2) implants remained intact throughout the testing with no evidence of creep fatigue or change in dynamic modulus; 3) the device could be reliably deployed in the desired placement locations and was appropriate for various anatomies; and 4) all implants were well tolerated through 1 year, with minimal inflammatory responses.

CONCLUSION

This new minimally invasive device for OSA has been demonstrated, through various bench and animal testing, to be safe, well tolerated, suitable for long-term use, and to function as intended. No adverse health consequences were observed in the animals, and histological evaluation indicated good healing. This study establishes proof of concept and supports human trials.

Anterolateral Advancement Pharyngoplasty: A New Technique for Treatment of Obstructive Sleep Apnea

OBJECTIVE

To investigate the efficacy of anterolateral advancement pharyngoplasty to enlarge pharyngeal airspace and to decrease palatal and lateral pharyngeal wall collapse in the treatment of obstructive sleep apnea (OSA).

STUDY DESIGN

Prospective study.

SETTING

University medical hospital.

SUBJECTS AND METHOD

Forty-one patients underwent an anterolateral advancement pharyngoplasty procedure according to the following criteria: body mass index <30 kg/m(2), Friedman stage II or III, type I Fujita, nocturnal polysomnography diagnostic of OSA, retropalatal and lateral pharyngeal collapse, and diagnosis with flexible nasoendoscopy during a Müller's maneuver based on a 5-point scale. Patients with retroglossal airway collapse were excluded from the study. The principle of this technique is to advance and fix the palatopharyngeus muscle with the superior pharyngeus constrictor muscle without transecting any of their fascicules anterolateral to the pterygomandibular raphe and anterosuperior to the levator veli palatine muscle.

RESULTS

Pre- and postoperative polysomnography findings (mean ± SD) showed significant statistical differences: apnea hypopnea index (AHI) decreased from 42.1 ± 16.34 to 16.3 ± 10.3 (P ≤ .001); percentage of time with oxyhemoglobin saturation <90% decreased from 18.5% ± 4.2% to 10.1% ± 1.3% (P ≤ .001); and lowest oxygen saturation level increased from 79.9% ± 14.8% to 89.3% ± 11.1% (P ≤ .05). The mean time for patients to return to a normal diet was 12.2 days. There was no postoperative bleeding, velopharyngeal insufficiency, speech alternations, or taste loss. Based on a threshold of a 50% reduction in AHI and AHI <20, surgical success was 86.8%.

CONCLUSION

Anterolateral advancement pharyngoplasty appears to be an effective technique with a high surgical success rate in the treatment of OSA patients with lateral pharyngeal wall collapse.

New developments in the use of positive airway pressure for obstructive sleep apnea

Obstructive sleep apnea (OSA) is a disorder which afflicts a large number of individuals around the world. OSA causes sleepiness and is a major cardiovascular risk factor. Since its inception in the early 1980's, continuous positive airway pressure (CPAP) has emerged as the major treatment of OSA, and it has been shown to improve sleepiness, hypertension, and a number of cardiovascular indices. Despite its successes, adherence with treatment remains a major limitation. Herein we will review the evidence behind the use of positive airway pressure (PAP) therapy, its various modes, and the methods employed to improve adherence. We will also discuss the future of PAP therapy in OSA and personalization of care.

The Effect of Body Position on Physiological Factors that Contribute to Obstructive Sleep Apnea

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) resolves in lateral sleep in 20% of patients. However, the effect of lateral positioning on factors contributing to OSA has not been studied. We aimed to measure the effect of lateral positioning on the key pathophysiological contributors to OSA including lung volume, passive airway anatomy/collapsibility, the ability of the airway to stiffen and dilate, ventilatory control instability (loop gain), and arousal threshold.

DESIGN

Non-randomized single arm observational study.

SETTING

Sleep laboratory.

PATIENTS/PARTICIPANTS

20 (15M, 5F) continuous positive airway pressure (CPAP)-treated severe OSA patients.

INTERVENTIONS

Supine vs. lateral position.

MEASUREMENTS

CPAP dial-downs performed during sleep to measure: (i) Veupnea: asleep ventilatory requirement, (ii) passive V0: ventilation off CPAP when airway dilator muscles are quiescent, (iii) Varousal: ventilation at which respiratory arousals occur, (iv) active V0: ventilation off CPAP when airway dilator muscles are activated during sleep, (v) loop gain: the ratio of the ventilatory drive response to a disturbance in ventilation, (vi) arousal threshold: level of ventilatory drive which leads to arousal, (vii) upper airway gain (UAG): ability of airway muscles to restore ventilation in response to increases in ventilatory drive, and (viii) pharyngeal critical closing pressure (Pcrit). Awake functional residual capacity (FRC) was also recorded.

RESULTS

Lateral positioning significantly increased passive V0 (0.33 ± 0.76L/min vs. 3.56 ± 2.94L/min, P < 0.001), active V0 (1.10 ± 1.97L/min vs. 4.71 ± 3.08L/min, P < 0.001), and FRC (1.31 ± 0.56 L vs. 1.42 ± 0.62 L, P = 0.046), and significantly decreased Pcrit (2.02 ± 2.55 cm H2O vs. -1.92 ± 3.87 cm H2O, P < 0.001). Loop gain, arousal threshold, Varousal, and UAG were not significantly altered.

CONCLUSIONS

Lateral positioning significantly improves passive airway anatomy/collapsibility (passive V0, pharyngeal critical closing pressure), the ability of the airway to stiffen and dilate (active V0), and the awake functional residual capacity without improving loop gain or arousal threshold.

Barbed Roman blinds technique for the treatment of obstructive sleep apnea: how we do it?

Retro-palatal obstruction is often involved in the pathogenesis of obstructive sleep apnea syndrome (OSAS), which is currently treated by means of various surgical procedures. The aim of this paper is to describe our preliminary results using a new, minimally invasive and non-resective procedure called the "barbed Roman blinds technique" (BRBT), which was used to treat severe OSAS due to retro-palatal obstruction. The apnea-hypopnea index (AHI), time with <90 % O2 saturation, and Epworth Sleepiness Scale (ESS) of 32 consecutive adult outpatients (mean age 47.3 ± 8.6 years) were compared before and after surgery. The tolerability of the procedure was assessed using a 0-10 visual analog scale (VAS). All of the treated patients experienced a clinical and subjective improvement as documented by the significant differences (P < 0.001) in their pre- and post-BRBT AHI, time with <90 % O2 saturation, and ESS scores. There were no minor or major adverse events, and the good tolerability of the procedure was documented by the short mean hospital stay (1.2 ± 0.5 days) and the mean VAS value of 4.3 ± 0.7. The mean follow-up period was 12.2 ± 2.0 months. The preliminary results indicate that the BRBT is safe and effective, but long-term follow-up and comparative studies of larger case series are needed to confirm these encouraging findings.

Pharyngeal mucosal wall folds in subjects with obstructive sleep apnea

Mechanical processes underlying pharyngeal closure have not been examined. We hypothesized that the pharyngeal mucosal surface would fold during closure, and lowering the upper airway lining liquid surface tension would unfold areas of mucosal apposition, i.e., folds. We compared baseline pharyngeal fold numbers and response to reduction in upper airway liquid surface tension in healthy and obstructive sleep apnea (OSA) subjects. Awake, gated magnetic resonance pharyngeal airway images of 10 healthy and 11 OSA subjects were acquired before and after exogenous surfactant administration (beractant). Upper airway liquid surface tension was measured at the beginning and end of image acquisition and averaged. Velopharyngeal and oropharyngeal images were segmented and analyzed separately for average cross-sectional area, circumference, and fold number. Compared with healthy subjects, at baseline, velopharynx for OSA subjects had a smaller cross-sectional area (98.3 ± 32.5 mm(2) healthy, 52.3 ± 23.6 mm(2) OSA) and circumference (46.5 ± 8.1 mm healthy, 30.8 ± 6.1 mm OSA; both P < 0.05, unpaired t-test), and fewer folds (4.9 ± 1.6 healthy, 3.1 ± 1.8 OSA, P < 0.03). There were no differences in oropharynx for cross-sectional area, circumference, or folds. Reduction in upper airway liquid surface tension from 61.3 ± 1.2 to 55.3 ± 1.5 mN/m (P < 0.0001) did not change cross-sectional area or circumference for velopharynx or oropharynx in either group; however, in OSA subjects, oropharyngeal folds fell from 6.8 ± 3.1 to 4.7 ± 1.2 (n = 8, P < 0.05), and velopharyngeal folds from 3.3 ± 1.9 to 2.3 ± 1.2 (P = 0.08), and were unchanged in healthy subjects. Subjects with OSA have fewer velopharyngeal wall folds, which decrease further when surface tension falls. We speculate that reduced pharyngeal wall folds contribute to an increase in pharyngeal collapsibility.

CPAP washout prior to reevaluation polysomnography: a sleep surgeon's perspective

PURPOSE

Obstructive sleep apnea (OSA) is characterized by repetitive upper airway collapse during sleep, leading to decreased oxygen blood levels and arousal from sleep. The gold standard treatment option for moderate to severe OSA is considered continuous positive airway pressure (CPAP). In case primary treatment with CPAP fails, a reevaluation of disease severity [by means of the apnea/hypopnea-index (AHI)] can be required. A subset of patients that prefer a CPAP alternative is still using CPAP until the reevaluation polysomnography (PSG), and a so-called washout effect is not ruled out. The purpose of this study is to evaluate the evidence on the existence and duration of this washout effect and its clinical relevance for current practice.

METHODS

To identify papers for this review, an extensive literature search was run electronically through MEDLINE and EMBASE databases.

RESULTS

An overview of currently available literature on this washout effect and the findings of 13 studies on this topic are discussed.

CONCLUSION

There is some evidence that CPAP washout exists in patients with a stable BMI throughout the follow-up period. However, the intensity and duration of this effect remains unclear. Within the limitations of the present study, it seems reasonable to maintain a washout period of 1 week, in case alternative treatments options are considered and especially when a baseline PSG (and subsequent repeat PSG after treatment) is needed in case of clinical trials.

Heritability of craniofacial structures in normal subjects and patients with sleep apnea

OBJECTIVES

Accumulating evidence has shown that there is a genetic contribution to obstructive sleep apnea (OSA).The objectives were to use magnetic resonance imaging (MRI) cephalometry to (1) confirm heritability of craniofacial risk factors for OSA previously shown by cephalometrics; and (2) examine the heritability of new craniofacial structures that are measurable with MRI.

DESIGN

A sib pair "quad" design examining apneics, apneic siblings, controls, and control siblings. The study design used exact matching on ethnicity and sex, frequency matching on age, and statistical control for differences in age, sex, ethnicity, height, and weight.

SETTING

Academic medical center.

PATIENTS

We examined 55 apneic probands (apnea-hypopnea index [AHI]: 46.8 ± 33.5 events/h), 55 proband siblings (AHI: 11.1 ± 15.9 events/h), 55 controls (AHI: 2.2 ± 1.7 events/h), and 55 control siblings (AHI: 4.1 ± 4.0 events/h).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Five independent domains reflecting different aspects of the craniofacial structure were examined. We confirmed heritability of sella-nasion-subspinale (38%, P = 0.002), saddle angle (55%, P < 0.0001), mandibular length (24%, P = 0.02) and lower facial height (33%, P = 0.006) previously measured by cephalometry. In addition, the current study added new insights by demonstrating significant heritability of mandibular width (30%, P = 0.005), maxillary width (47%, P < 0.0001), distance from the hyoid bone to the retropogonion (36%, P = 0.0018) and size of the oropharyngeal space (31%, P = 0.004). Finally, our data indicate that heritability of the craniofacial structures is similar in normal patients and those with apnea.

CONCLUSIONS

The data support our a priori hypothesis that the craniofacial structures that have been associated with obstructive sleep apnea (OSA) are heritable. We have demonstrated heritability for several intermediate craniofacial phenotypes for OSA. Thus, we believe that future studies should be able to identify genes associated with these intermediate craniofacial phenotypes.

Advances in airway clearance technologies for chronic obstructive pulmonary disease

Techniques to promote clearance of sputum from the airways (airway clearance techniques; ACTs) have existed in clinical practice for more than a century. This review examines current evidence and clinical recommendations regarding ACTs for individuals with chronic obstructive pulmonary disease. Comparisons between this literature and reports of current practice suggest that discrepancies may exist in relation to the clinical management of sputum in individuals with COPD. The novel application of newer technologies has enhanced our ability to assess the complex physiological processes underpinning airway clearance therapy. The potential for physiologically tailored ACT prescription may, however, depend on the capacity for translation of such technology from the research setting into the clinical environment. Future directions regarding this common form of therapy will be discussed, including identification of the key research priorities to optimize evidence-based practice in this area.

New frontiers in obstructive sleep apnoea

OSA (obstructive sleep apnoea), the most common respiratory disorder of sleep, is caused by the loss of upper airway dilating muscle activity during sleep superimposed on a narrow upper airway. This results in recurrent nocturnal asphyxia. Termination of these events usually requires arousal from sleep and results in sleep fragmentation and hypoxaemia, which leads to poor quality sleep, excessive daytime sleepiness, reduced quality of life and numerous other serious health consequences. Furthermore, patients with untreated sleep apnoea are at an increased risk of hypertension, stroke, heart failure and atrial fibrillation. Although there are many predisposing risk factors for OSA, including male gender, endocrine disorders, use of muscle relaxants, smoking, fluid retention and increased age, the strongest risk factor is obesity. The aim of the present review is to focus on three cutting-edge topics with respect to OSA. The section on animal models covers various strategies used to simulate the physiology or the effects of OSA in animals, and how these have helped to understand some of the underlying mechanisms of OSA. The section on diabetes discusses current evidence in both humans and animal models demonstrating that intermittent hypoxia and sleep fragmentation has a negative impact on glucose tolerance. Finally, the section on cardiovascular biomarkers reviews the evidence supporting the use of these biomarkers to both measure some of the negative consequences of OSA, as well as the potential benefits of OSA therapies.

Changes in the calibre of the upper airway and the surrounding structures after maxillomandibular advancement for obstructive sleep apnoea

Maxillomandibular advancement (MMA) is effective in the treatment of obstructive sleep apnoea. We aimed to assess changes in the calibre of the upper airway, facial skeleton, and surrounding structural position after MMA and their association with improvement in symptoms. Sixteen consecutive adults with moderate-to-severe apnoea were treated by primary MMA. Polysomnography and computed tomography (CT) of the head and neck were done before and at least 6 months after MMA. The calibre of the upper airway, the facial skeleton, and the surrounding structures were measured with image analysis software. After MMA, patients had a significant reduction in their apnoea-hypopnoea index (31.2 (18.8)number of events (n)/hour (h)). The mean (SD) volume of the airway increased significantly in the velopharynx (p<0.01), oropharynx (p=0.001), and hypopharynx (p<0.001) (by 2.3 (2.4), 2.1 (2.6), and 1.7 (1.1)cm(3), respectively) and the length of the airway was significantly decreased (by 3.1 (3.5)mm p<0.01). The soft palate (p<0.001), tongue (p<0.001), and hyoid (p=0.001) moved significantly anteriorly (by 4.4 (2.0), 7.5 (2.8), and 5.7 (5.0)mm, respectively), and these movements were related to the MMA (r=0.6-0.8). The improvement in the apnoea-hypopnoea index was associated with both maxillary advancement and anterior movements of the soft palate and hyoid (r=0.6-0.7). The results of this study suggest that MMA increases the volume in the upper airway and reduces its length. Improvement in obstructive sleep apnoea is associated with the extent of the anterior movements of the maxilla, soft palate, and hyoid.

Upper airway anatomical balance contributes to optimal continuous positive airway pressure for Japanese patients with obstructive sleep apnea syndrome

BACKGROUND

The aim of this study was to examine whether the upper airway anatomical balance, as reflected by tongue size relative to maxillomandibular size, is related to optimal nasal continuous positive airway pressure (PnCPAP).

METHODS

Sixty-six male Japanese obstructive sleep apnea syndrome (OSAS) patients (median apnea-hypopnea index [AHI] = 33.9 episodes/h [10th/90th percentile = 19.5/59.9], median body mass index [BMI] = 25.1 kg/m(2) [10th/90th percentile = 21.2/30.4]) were recruited. All patients underwent standard polysomnography (PSG), and PnCPAP was determined by nasal continuous positive airway pressure (nCPAP) titration. The anatomical balance was defined as the tongue area (TG) divided by the lower face cage (LFC) measured on cephalometry. A predictive equation of PnCPAP was created using demographic, polysomnographic, and cephalometric variables.

RESULTS

Significant correlations were found between PnCPAP and descriptive variables, including BMI, AHI, lowest SpO2, distance from the anterosuperior point of the hyoid bone to the mandibular plane (MP-H), and TG/LFC. Stepwise multiple regression analysis revealed that AHI and TG/LFC were independent predictors of PnCPAP. The predictive equation was: PnCPAP = 1.000 + 0.043 × AHI + 9.699 × TG / LFC, which accounted for 28.0% of the total variance in PnCPAP (R(2) = 0.280, p < 0.01).

CONCLUSIONS

Anatomical balance of upper airway in addition to the severity of OSAS is an important contributing factor for PnCPAP in Japanese OSAS patients.

The dimension of hyoid bone is independently associated with the severity of obstructive sleep apnea

Introduction

We hypothesized that the size of the hyoid bone itself may affect the severity of sleep apnea. The aim of this study was to identify the relationship between hyoid bone dimensions and the severity of sleep apnea using computerized tomography (CT) axial images.

Methods

We retrospectively measured the hyoid bone in axial images of neck CTs and correlated these measurements with results of polysomnography in a total of 106 male patients. The new hyoid bone parameters studied in this study were as follows: distance between bilateral lesser horns (LH-d), distance between bilateral greater horns (GH-d), distance from the most anterior end of the hyoid arch to GH-d (AP), distance from the greater to the lesser horn on right and left sides (GH-LH), and the anterior angle between bilateral extensive lines from the greater to the lesser horn (H-angle). Data was analyzed using univariate and multivariate logistic regression, and Pearson correlation tests.

Results

We found a significant inverse correlation between the apnea-hypopnea index (AHI) and GH-d or AP. Neither the LH-d, GH-LH, nor H-angle were associated with the AHI. The patient group that met the criteria of both GH-d<45.4 and AP<33.4 demonstrated the most severe AHI.

Conclusion

The lateral width or antero-posterior length of hyoid bone was associated with AHI and predicted the severity of sleep apnea in male patients. This finding supports the role of expansion hyoidplasty for treatment of sleep apnea. Pre-operative consideration of these parameters may improve surgical outcomes in male patients with sleep apnea.

Obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive collapse of the pharyngeal airway during sleep. Control of pharyngeal patency is a complex process relating primarily to basic anatomy and the activity of many pharyngeal dilator muscles. The control of these muscles is regulated by a number of processes including respiratory drive, negative pressure reflexes, and state (sleep) effects. In general, patients with OSA have an anatomically small airway the patency of which is maintained during wakefulness by reflex-driven augmented dilator muscle activation. At sleep onset, muscle activity falls, thereby compromising the upper airway. However, recent data suggest that the mechanism of OSA differs substantially among patients, with variable contributions from several physiologic characteristics including, among others: level of upper airway dilator muscle activation required to open the airway, increase in chemical drive required to recruit the pharyngeal muscles, chemical control loop gain, and arousal threshold. Thus, the cause of sleep apnea likely varies substantially between patients. Other physiologic mechanisms likely contributing to OSA pathogenesis include falling lung volume during sleep, shifts in blood volume from peripheral tissues to the neck, and airway edema. Apnea severity may progress over time, likely due to weight gain, muscle/nerve injury, aging effects on airway anatomy/collapsibility, and changes in ventilatory control stability.

Neural control of the upper airway: integrative physiological mechanisms and relevance for sleep disordered breathing

The various neural mechanisms affecting the control of the upper airway muscles are discussed in this review, with particular emphasis on structure-function relationships and integrative physiological motor-control processes. Particular foci of attention include the respiratory function of the upper airway muscles, and the various reflex mechanisms underlying their control, specifically the reflex responses to changes in airway pressure, reflexes from pulmonary receptors, chemoreceptor and baroreceptor reflexes, and postural effects on upper airway motor control. This article also addresses the determinants of upper airway collapsibility and the influence of neural drive to the upper airway muscles, and the influence of common drugs such as ethanol, sedative hypnotics, and opioids on upper airway motor control. In addition to an examination of these basic physiological mechanisms, consideration is given throughout this review as to how these mechanisms relate to integrative function in the intact normal upper airway in wakefulness and sleep, and how they may be involved in the pathogenesis of clinical problems such obstructive sleep apnea hypopnea.