The effect of nasal and oral breathing on airway collapsibility in patients with obstructive sleep apnea: Computational fluid dynamics analyses

Does obstructive sleep apnea-induced intermittent hypoxia increase the incidence of solitary pulmonary nodules, thyroid nodules, and other disorders? A retrospective study based on 750 cardiovascular disease patients

BACKGROUND

Obstructive sleep apnea (OSA) has been shown to be an important risk factor for cardiovascular disease (CVD), and intermittent hypoxia is an important pathogenetic factor for it. In the clinic, it was found that most CVD patients combined with OSA were also combined with solitary pulmonary nodules (SPN) or thyroid nodules (TN). Are these disorders related to intermittent hypoxia? One study showed that intermittent hypoxia is a pathogenic factor for lung cancer in mice, but there have been no clinical reports. So we conducted a retrospective study to explore whether intermittent hypoxia caused by OSA increases the incidence of SPN, TN, and other disorders.

METHODS

We selected 750 patients with cardiovascular disease (CVD), who were divided into the control group and the OSA group according to the result of portable sleep monitoring. Retrospectively analyzed the comorbidities that patients with OSA are prone to and explored the correlation between OSA and those comorbidities.

RESULTS

The incidence of SPN, TN, cervical spondylosis, and carotid-artery plaques was higher in the OSA group than in the control group. These diseases are significantly associated with OSA (p < 0.05), and their incidence increased with an elevated apnea-hypopnea index. After excluding interference from age, gender, BMI, smoking history, history of lung disease, and history of tumors, OSA showed a significant correlation with SPN. After excluding age, gender, BMI, and thyroid disease, OSA was associated with TN. Patients with comorbidities have lower nocturnal oxygen saturation and more extended periods of apnea. Logistic multiple regression results revealed that male, advanced age, obesity, CS, and nasal septum deviation were independent risk factors for OSA.

CONCLUSIONS

Patients combined with OSA may further develop more comorbidities, such as SPN, TN, and carotid-artery plaques. It may be related to intermittent hypoxia caused by OSA.

Expiratory Velopharyngeal Obstruction: Sleep Endoscopy-Guided Treatment Strategies to Prevent Oral Breathing During Sleep

OBJECTIVE

Obstructive sleep apnea (OSA) is a prevalent disorder, with oral breathing influencing its severity. Expiratory velopharyngeal obstruction (EVO), observed during drug-induced sleep endoscopy (DISE), may contribute to oral breathing in OSA patients. EVO results in obstruction between the pharynx and nasal cavity during expiration. This study aims to identify factors associated with positive EVO during DISE.

STUDY DESIGN

Case series.

SETTING

Tertiary Medical Center.

METHODS

Seventy-two OSA patients underwent clinical evaluation, polysomnography, and DISE, utilizing interventions like intraoral negative airway pressure (iNAP), mouth closure, and oral appliances (OAs) in supine positions with head rotation. The findings, classified under velopharynx, oropharynx, tongue base, epiglottis, included the presence of EVO.

RESULTS

The results demonstrated that interventions including mouth closure and iNAP were associated with increased observation of EVO (43.1% and 34.7%) compared to OA (20.1%). However, head rotation was associated with decreased presence of EVO during DISE compare to supine (26% vs 35.8%). Noticeably, per 1 year increase of age was associated with an increased odds of EVO (odds ratio: 1.03, 95% confidence interval: 1.01-1.06). However, no other baseline characteristics were significantly associated the odds of EVO.

CONCLUSION

Our study reveals the effectiveness of head rotation and OA in reducing EVO and improving mouth breathing in OSA patients, offering valuable insights for future treatment strategies.

Does cosmetic rhinoplasty affect sleep quality and/or contribute to the development of obstructive sleep apnea?

OBJECTIVE

Rhinoplasty can reduce nasal airways' resistance. This study evaluates the effects of rhinoplasty on sleep quality, daytime drowsiness, and obstructive sleep apnea (OSA).

METHODS

In this prospective cohort study, 80 rhinoplasty candidates were examined before and six months after rhinoplasty to evaluate symptom changes. STOP-BANG, Pittsburgh Sleep Quality Index (PSQI), and Epworth Sleepiness Scale (ESS) questionnaires, and nocturnal polysomnography were used, respectively, to screen for OSA, assess sleep quality, assess daytime drowsiness, and confirm results.

RESULTS

Seventeen men (21.2%) and 63 women (78.8%) were studied. PSQI results showed an increase only in post-operative sleep disturbance items (p = 0.04). STOP-BANG showed an increase in apnea (p = 0.06) and a decrease in snoring (p = 0.06), which were both insignificant. The polysomnography tests confirmed the results of the questionnaires.

CONCLUSION

Contrary to popular belief, rhinoplasty does not increase snoring, sleep disorders, or apnea.

[Effect of mouth breathing on upper airway structure in patients with obstructive sleep apnea]

Objective:To compare the changes of morphology of pharynx in patients with obstructive sleep apnea hypopnea syndrome （OSAHS） and healthy individuals during oral or nasal breathing, and explore the relevant influencing factors. Methods:Twenty-nine adult patients with OSAHS and 20 non-snoring controls underwent MRI to obtain upper airway structural measurements while the subjects were awake and during mouth breathing with a nasal clip.The following were analyzed. ①The changes of upper airway structure of oral and nasal respiration in non-snoring control/OSAHS patients were observed; ②The differences and influencing factors of upper airway structure changes between OSAHS patients and controls were compared during breathing. Results:The control group consisted of 15 males and 5 females, with an apnea-hypopnea index （AHI）<5 events/h, while the OSAHS group comprised 26 males and 3 females with an AHI of 40.4±23.1 events/h and the mean lowest arterial oxygen saturation （LSaO2） was 79.5% ±10.0%. In the both groups, the vertical distance between the mandible and the posterior pharyngeal wall decreased （P<0.05）; The long axis of tongue body decreased （P<0.05）, and the contact area between tongue and palate decreased. There was no significant change in the total volume of the retropalatine（RP） and retroglossal（RG） airway in the control group （P>0.05）. However, the minimum cross-sectional area and volume of the RP airway in OSAHS decreased （P<0.001）. The lateral diameters of uvula plane in OSAHS decreased during mouth breathing, which was contrary to the trend in the control group （P=0.017）. The AHI of patients was positively correlated with the reduction of the volume of the RP airway during oral breathing （P=0.001）; The reduction of the distance between the mandible and the posterior pharyngeal wall was positively correlated with the length of the airway （P<0.001）. Conclusion:Mouth breathing leads to the shortening of the long axis of the tongue, the reduction of the contact area between the soft palate and the tongue, vertical distance between the mandible and the posterior pharyngeal wall, and the cross-sectional area of the epiglottis plane. These changes vary between OSAHS patients and controls. During mouth breathing, the diameters, areas and volumes of the RP area decreased, and were more significant in severe cases.

Computational fluid-structure interaction analysis of flapping uvula on aerodynamics and pharyngeal vibration in a pediatric airway

The uvula flapping is one of the most distinctive features of snoring and is critical in affecting airway aerodynamics and vibrations. This study aimed to elucidate the mechanism of pharyngeal vibration and pressure fluctuation due to uvula flapping employing fluid-structure interaction simulations. The followings are the methodology part: we constructed an anatomically accurate pediatric pharynx model and put attention on the oropharynx region where the greatest level of upper airway compliance was reported to occur. The uvula was assumed to be a rigid body with specific flapping frequencies to guarantee proper boundary conditions with as little complexity as possible. The airway tissue was considered to have a uniform thickness. It was found that the flapping frequency had a more significant effect on the airway vibration than the flapping amplitude, as the flapping uvula influenced the pharyngeal aerodynamics by altering the jet flow from the mouth. Breathing only through the mouth could amplify the effect of flapping uvula on aerodynamic changes and result in more significant oropharynx vibration.

Holistic care for obstructive sleep apnea (OSA) with an emphasis on restoring nasal breathing: A review and perspective

Obstructive sleep apnea (OSA) is characterized by partial or complete airway blockage during sleep. Nocturnal nasal obstruction usually leads to mouth breathing while sleeping, which worsens sleep apnea by aggravating tongue base and lateral pharyngeal wall collapse. The pathogenesis of OSA is multifactorial, and the precipitating factors vary significantly among individuals. Although continuous positive airway pressure (CPAP) is considered the first-line therapy for OSA, its adherence rate remains a challenge. Oral appliances are more suitable for simple snorers or patients with mild OSA. Maxillomandibular advancement (MMA) is highly effective for treating those with mandibular retrognathia and moderate-to-severe OSA. Intrapharyngeal surgeries yield favorable outcomes in patients with large tonsils and low tongue resting position (Friedman Stage I); however, their efficacy declines with time. Each therapy has its own strength and weakness; thus, the principle of multimodality treatment should be adopted. Nasal surgery plays an indispensable role in the holistic care for OSA. In addition to alleviating nasal congestion, nasal surgery significantly reduces snoring intensity and daytime sleepiness, which improves the quality of life of patients with OSA. Although it significantly reduces the respiratory disturbance index, its effect on the apnea-hypopnea index remains controversial. A combination of nasal surgery and multilevel pharyngeal surgery may result in better prognosis. Nasal surgery can significantly reduce the therapeutic pressure and improve the CPAP compliance of patients undergoing CPAP therapy. In conclusion, multimodality treatment and holistic care for OSA should involve nasal surgery for optimizing treatment outcomes.

Breathing Exercises for Improving Cognitive Function in Patients with Stroke

Patients with stroke may experience a certain degree of cognitive decline during the period of recovery, and a considerable number of such patients have been reported to show permanent cognitive damage. Therefore, the period of recovery and rehabilitation following stroke is critical for rapid cognitive functional improvements. As dysfunctional breathing has been reported as one of the factors affecting the quality of life post stroke, a number of studies have focused on the need for improving the breathing function in these patients. Numerous breathing exercises have been reported to enhance the respiratory, pulmonary, cognitive, and psychological functions. However, scientific evidence on the underlying mechanisms by which these exercises improve cognitive function is scattered at best. Therefore, it has been difficult to establish a protocol of breathing exercises for patients with stroke. In this review, we summarize the psychological, vascular, sleep-related, and biochemical factors influencing cognition in patients and highlight the need for breathing exercises based on existing studies. Breathing exercises are expected to contribute to improvements in cognitive function in stroke based on a diverse array of supporting evidence. With relevant follow-up studies, a protocol of breathing exercises can be developed for improving the cognitive function in patients with stroke.

Nasopharyngeal collapse can be identified on radiography in healthy male Beagle dogs without cardiopulmonary diseases

Pharyngeal collapse has been described as a decrease of more than 50% in the diameter of the lumen. However, there has been no study on changes in the pharyngeal lumen in clinically normal dogs. The hypothesis of this prospective, observational, and pilot study was that change in nasopharyngeal lumen would be over 50% in Beagle dogs without cardiopulmonary diseases. Thus, we assessed the nasopharyngeal luminal change using cervical radiography in Beagle dogs without respiratory signs or cardiac abnormalities. The study sample included 42 Beagle dogs without cardiopulmonary diseases. Cervical radiographies were acquired during inspiration and expiration, and nasopharyngeal luminal change (%) was calculated. The median nasopharyngeal luminal change was 16.6%, and nasopharyngeal luminal change over 50% was identified in two dogs. The nasopharyngeal luminal change was significantly associated with body condition score and body weight. There was no correlation between nasopharyngeal luminal change and age. This study revealed that change in nasopharyngeal lumen over 50% can be identified in Beagle dogs without cardiopulmonary diseases and may be over-diagnosed as partial pharyngeal collapse. Further studies for comparing change in nasopharyngeal lumen between clinically normal dogs and dogs with respiratory signs are warranted.

Mouth Closing to Improve the Efficacy of Mandibular Advancement Devices in Sleep Apnea

RATIONALE

Mouth breathing increases upper airway collapsibility, leading to decreased efficacy of obstructive sleep apnea (OSA) treatments. We hypothesized that the use of mandibular advancement devices (MAD) increases mouth breathing and, thus, using an adhesive mouthpiece (AMT), to prevent mouth breathing, in combination with MAD can improve the treatment efficacy.

OBJECTIVES

To evaluate the efficacy of MAD + AMT in comparison to MAD alone.

METHODS

A prospective crossover pilot study was designed to test this hypothesis. Briefly, adult participants with an apnea-hypopnea index (AHI) between 10-50 events/h at the screening visit were randomized to no treatment (baseline), MAD treatment, AMT treatment, and MAD+AMT treatment. As a primary analysis, absolute AHI was compared between MAD and MAD + AMT arms. Secondary analyses included quantifying the percent change in AHI, percentage of complete (AHI < 5 events/h) and incomplete (AHI 5 - 10 events/h) responders, and the efficacy of AMT alone in comparison with other treatment arms.

RESULTS

A total 21 of participants were included. (Baseline AHI= 24.3±9.9 event/h) The median AHI (Interquartile [IQR]) in the MAD and MAD+AMT arms were 10.5 [5.4-19.6] events/h and 5.6 [2.2-11.7] events/h (p-value= 0.02), respectively. A total of 76% of individuals achieved an AHI < 10 events/h in the MAD + AMT arm vs. 43% in the MAD arm (p-value<0.01). Finally, the observed effect was similar in moderate to severe OSA (AHI ≥15 events/h) in terms of absolute reduction and treatment responders, and AMT alone did not significantly reduce the AHI compared to baseline.

CONCLUSION

Combination of an adhesive mouthpiece and MAD is a more effective therapy than MAD alone. These findings may help improve clinical decision-making in sleep apnea.

Analysis of conductive olfactory dysfunction using computational fluid dynamics

Conductive olfactory dysfunction (COD) is caused by an obstruction in the nasal cavity and is characterized by changeable olfaction. COD can occur even when the olfactory cleft is anatomically normal, and therefore, the cause in these cases remains unclear. Herein, we used computational fluid dynamics to examine olfactory cleft airflow with a retrospective cohort study utilizing the cone beam computed tomography scan data of COD patients. By measuring nasal–nasopharynx pressure at maximum flow, we established a cut-off value at which nasal breathing can be differentiated from combined mouth breathing in COD patients. We found that increased nasal resistance led to mouth breathing and that the velocity and flow rate in the olfactory cleft at maximum flow were significantly reduced in COD patients with nasal breathing only compared to healthy olfactory subjects. In addition, we performed a detailed analysis of common morphological abnormalities associated with concha bullosa. Our study provides novel insights into the causes of COD, and therefore, it has important implications for surgical planning of COD, sleep apnea research, assessment of adenoid hyperplasia in children, and sports respiratory physiology.

A preoperative predictive study of advantages of airway changes after maxillomandibular advancement surgery using computational fluid dynamics analysis

The purpose of this study was to develop a simulation approach for predicting maxillomandibular advancement-induced airway changes using computational fluid dynamics. Eight patients with jaw deformities who underwent maxillomandibular advancement and genioglossus advancement surgery were included in this study. Computed tomography scans and rhinomanometric readings were performed both preoperatively and postoperatively. Computational fluid dynamics models were created, and airflow simulations were performed using computational fluid dynamics software; the preferable number of computational mesh points was at least 10 million cells. The results for the right and left nares, including simulation and postoperative measurements, were qualitatively consistent, and surgery reduced airflow pressure loss. Geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. Simulations were performed with either the right or left naris blocked, and the predicted values were similar to those found clinically. In addition, geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. These findings suggest that geometry prediction simulation facilitates the preoperative prediction of the postoperative structural outcome.

Respiratory sleep disorders, nasal obstruction and enuresis in children with non-syndromic Pierre Robin sequence

INTRODUCTION

Obstructive sleep apnea is highly prevalent in non-syndromic Pierre Robin sequence patients. Studies have found a probable relationship between obstructive sleep apnea and nasal obstruction and between obstructive sleep apnea and enuresis. Assessment of the relationship between these variables in non-syndromic Pierre Robin sequence patients is scarce.

OBJECTIVE

The present study aims to evaluate the relationship between symptoms of obstructive sleep apnea, nasal obstruction and enuresis, determining the prevalence of symptoms suggestive of these conditions, in schoolchildren with non-syndromic Pierre Robin sequence, and describe the prevalence of excessive daytime sleepiness habitual snoring and voiding dysfunction symptoms associated with enuresis.

METHODS

This was a prospective analytical cross-sectional study developed at a reference center. Anthropometric measurements and a structured clinical interview were carried out in a sample of 48 patients. The instruments "sleep disorders scale in children" "nasal congestion index questionnaire" (CQ-5), and the "voiding dysfunction symptom score questionnaire" were used. Statistical analysis was performed for p < 0.05.

RESULTS

Positive "sleep disorders scale in children" scores for obstructive sleep apnea and CQ-5 for nasal obstruction were observed in 38.78% and 16.33%, respectively. Enuresis was reported in 16.33% of children, being characterized as primary in 71.43% and polysymptomatic in 55.55%; according to the "voiding dysfunction symptom score questionnaire". There was a significant relationship between nasal obstruction and obstructive sleep apnea symptoms (p < 0.05), but no significance was found between obstructive sleep apnea symptoms and enuresis, and between nasal obstruction and enuresis. The prevalence of excessive daytime sleepiness was 12.24% and of habitual snoring, 48.98%. A family history of enuresis, younger age in years and a positive "voiding dysfunction symptom score questionnaire" score were associated with a higher prevalence of enuresis (p < 0.05).

CONCLUSION

Children with non-syndromic Pierre Robin sequence are at high risk for obstructive sleep apnea symptoms and habitual snoring, with a correlation being observed between nasal obstruction and obstructive sleep apnea symptoms. In addition, the study showed that non-syndromic Pierre Robin sequence, obstructive sleep apnea and nasal obstruction symptoms were not risk factors for enuresis in these patients.

Construction of a computational mechanical model of bronchi for practical simulation of the optimal positive intrathoracic pressure conditions during general thoracic surgery

BACKGROUND

Thoracic CO2 insufflation with positive intrathoracic pressure is usually effective during thoracoscopic surgery, however, lung collapse is sometimes insufficient. We hypothesized that inappropriate bronchial collapse might cause this unsuccessful lung collapse.

OBJECTIVE

The objective of this study was to construct a computational mechanical model of bronchi for practical simulation to discover the optimal conditions of positive intrathoracic pressure during thoracoscopic surgery.

METHODS

Micro-focus high-resolution X-ray computed tomography measurements of lungs from just-slaughtered swine were extracted, and the three-dimensional geometries of the bronchi under pressurized and depressurized conditions were measured accurately. The mechanical properties of the bronchus were also measured. Computational fluid dynamics (CFD) and computational structural mechanics (CSM) analyses were conducted.

RESULTS

The CSM results indicated that the present structural model could simulate bronchial occlusion. The CFD results showed that airflows from pressed lung alveoli might cause low-internal-pressure regions when suddenly or heterogeneously pushed airflow was injected from a small branching bronchus to a large bronchus. A preliminary computational mechanical model of bronchi was constructed.

CONCLUSIONS

We demonstrated the performance of the mechanical model of bronchi in rough simulations of bronchial occlusions. However, this model should be verified further using human data to facilitate its introduction to clinical use.

Breathing Re-Education and Phenotypes of Sleep Apnea: A Review

Four phenotypes of obstructive sleep apnea hypopnea syndrome (OSAHS) have been identified. Only one of these is anatomical. As such, anatomically based treatments for OSAHS may not fully resolve the condition. Equally, compliance and uptake of gold-standard treatments is inadequate. This has led to interest in novel therapies that provide the basis for personalized treatment protocols. This review examines each of the four phenotypes of OSAHS and explores how these could be targeted using breathing re-education from three dimensions of functional breathing: biochemical, biomechanical and resonant frequency. Breathing re-education and myofunctional therapy may be helpful for patients across all four phenotypes of OSAHS. More research is urgently needed to investigate the therapeutic benefits of restoring nasal breathing and functional breathing patterns across all three dimensions in order to provide a treatment approach that is tailored to the individual patient.