Comparison of the selection of nasotracheal tube diameter based on the patient's sex or size of the nasal airway: A prospective observational study.

When selecting the nasotracheal tube diameter for nasotracheal intubation, atraumatic introduction of the tube through the nasal passage and a safe location of the tube's cuff and tip should be ensured simultaneously. To maintain safety margin for the tube's cuff and tip from the vocal cords and carina (2 cm and 3 cm, respectively), the maximum allowable proximal-cuff-to-tip distance was calculated as 5 cm less than the measured vocal cords-to-carina distance. The primary aim of this study was to find a single predictive preoperative factor of the nostril size and maximum allowable proximal-cuff-to-tip distance of nasotracheal tubes. The secondary aim was to compare the difference in the safety margin between the maximum allowable proximal-cuff-to-tip distance based on the patient's airway and the actual proximal-cuff-to-tip distance of the selected tube. We used fiberoptic bronchoscope to measure the distance from the vocal cords to the carina for the calculation of the maximum allowable proximal-cuff-to-tip distance. We analyzed the association of preoperative characteristics such as age, sex, height, and weight with the nostril size and maximum allowable proximal-cuff-to-tip distance. The proportion of patients with appropriate locations of both the cuff and tip was evaluated. Sex and height were significant predictive factors of the nostril size and maximum allowable proximal-cuff-to-tip distance, respectively (p = 0.0001 and p = 0.0048). The difference in the safety margin was significantly decreased when the tube diameter was selected based on the nostril size rather than by sex (p<0.0001). The proportion of patients who had the appropriate cuff/tip location was significantly larger (75.2%) when the tube diameter was selected by sex compared to when it was selected by the nostril size (65%) (p<0.0001). It is more suitable to select the nasotracheal tube diameter based on sex rather than by nostril size to ensure the safe location of the tube's cuff and tip simultaneously.

Influence of computed tomographic dimensions of the nasopharynx on middle ear effusion and inflammation in pugs and French bulldogs with brachycephalic airway syndrome.

OBJECTIVE: To compare the prevalence of middle ear abnormalities in pugs and in French bulldogs and evaluate the influence of nasopharyngeal dimensions on middle ear effusion. STUDY DESIGN: Retrospective study. ANIMALS: Thirty pugs and 30 French bulldogs with brachycephalic airway syndrome and no known history of ear disease. METHODS: Computed tomographic (CT) studies were reviewed for middle ear effusion, mucosal contrast enhancement, signs of osteitis, and tympanic wall thickness. Soft palate thickness and cross-sectional areas of the nasopharynx at the opening of the auditory tube were measured and normalized to each individual's skull index before statistical comparison between breeds. Statistical dependence of middle ear abnormalities and nasopharyngeal dimensions was assessed by using Spearman's rank correlation tests. RESULTS: Middle ear effusion was observed in 17 of 30 (56.7%) French bulldogs and five of 30 (16.7%) pugs. Contrast enhancement of the tympanic bulla was noted in 25 of 60 (41.6%) French bulldog ears and three of 60 (5.0%) pug ears. The cross-sectional airway dimensions (difference [Δ] = 0.31 cm2 , P < .0001) and soft palate thickness (Δ = 0.44 cm, P < .0001) were reduced in pugs compared with in French bulldogs. Weak correlations were detected between soft palate thickness and nasopharyngeal dimensions and presence of tympanic bulla effusion (r = 0.324 and r = 0.198, respectively) or contrast enhancement (r = 0.270 and r = 0.199, respectively). CONCLUSION: Middle ear effusion and inflammation were more common in French bulldogs than in pugs and did not seem related to nasopharyngeal dimensions. CLINICAL SIGNIFICANCE: French bulldogs with brachycephalic airway syndrome seem predisposed to middle ear effusion and inflammation.

Why and When to Treat Snoring.

It is estimated that half of the adult population older than 60 years snores. This article discusses the many aspects of snoring, including impacts on bed partners, the individual who snores, and when and how to appropriately evaluate, diagnose, and treat the perpetrator. The goal is for clinicians to expand their knowledge regarding diagnosis and treatment of the phenomenon of snoring.It is estimated that half of the adult population over the age of 60 years of age snores. This chapter discusses snoring, including the impact on bed partners, the individual that snores and when and how to treat the snorer. The goal is for clinicians to expand their knowledge regarding diagnosis and treatment of patients who snores.

A feasibility study in the treatment of obstructive sleep apnea syndrome and snoring: Nasopharyngeal stent.

OBJECTIVE: The objective of this study is to create a new choice of treatment with nasopharyngeal stent in isolated retro palatal obstruction and snoring for the treatment of obstructive sleep apnea syndrome (OSAS). MATERIAL AND METHOD: The study included five patients with mild OSAS and snoring. Nasopharyngeal stents were applied in these patients with drug-induced sedation endoscopy. RESULTS: With the nasopharyngeal stents, we aimed to prevent the soft palate to fall backwards while sleeping, especially at supine position in order to prevent the occurrence of apnea and hypopnea, providing a way for the airway to remain open as well as a support behind the soft palate and thus prevent snoring based on the vibration created by draught. CONCLUSION: We suggest a new alternative treatment approach to devices that need to be continuously used such as CPAP or intraoral devices or surgical methods that have many unwanted discomforts for the patients.

Changes of the upper airway and bone in microimplant-assisted rapid palatal expansion: A cone-beam computed tomography (CBCT) study.

OBJECTIVE: To evaluate the changes of maxillary expansion and upper airway structure after microimplant assisted rapid palatal expansion (MARPE) using cone-beam computed tomography (CBCT). METHODS: This retrospective study included 19 subjects (15 females and 4 males) aged 15-29 years old (mean, 19.95±4.39 years) with maxillary transverse deficiency treated with MARPE. CBCT was performed at the initial diagnosis and 3 months after MARPE treatment. Measurements were taken to evaluate the amount of total expansion, skeletal expansion, and dental expansion at the maxillary first premolar (P1), second premolar (P2), first molar (M1), second molar (M2) regions and upper airway changes. RESULTS: After MARPE treatment, the maxillary skeletal base expansion, skeletal expansion, alveolar expansion and dental expansion were achieved at the P1, P2, M1, M2 region. The nasopharyngeal volume significantly increased 8.48% after MARPE treatment compared with that before the treatment (P < 0.05). The change of nasal lateral width (NLW) was also significantly different before and after MARPE (P < 0.05). However, there were no statistically significant change in the oropharyngeal, palatopharyngeal, glossopharyngeal and airway total volume (all P > 0.05). CONCLUSIONS: MARPE can produce more transverse bone expansion, relieve maxillary transverse deficiency and improve upper airway ventilation.

Comparison of sonotubometry, impedance, tubo-tympano-aerography, and tubomanometry to test eustachian tube function.

PURPOSE: There is currently no gold standard for the diagnosis of eustachian tube (ET) dysfunction. To provide an objective basis for the clinical diagnosis of ET dysfunction, we explored the characteristics of sonotubometry, impedance, tubo-tympano-aerography (TTAG), and tubomanometry (TMM) in volunteers with healthy ETs. MATERIALS AND METHODS: Sonotubometry, impedance, TTAG, and TMM tests were performed in 110 healthy ears of 55 volunteers, and the characteristics of each ET test were compared and discussed. RESULTS: The ET opening rate was compared between sonotubometry with dry swallowing, impedance with the Valsalva maneuver, TTAG with the Valsalva maneuver, and TMM with a nasopharyngeal pressure of 50 mbar in 100 (90.9%), 102 (92.7%), 99 (90.0%), and 104 (94.5%) ears, respectively; there was no significant difference among the four methods (P = 0.575). In sonotubometry, both dry swallowing and the Valsalva maneuver were superior to wet swallowing in terms of detecting ET opening (P = 0.000). In TMM, both the opening rate and the external auditory canal pressure were positively correlated with the nasopharyngeal pressure. Specifically, the opening rate and external auditory canal pressure increased with an increase in the nasopharyngeal pressure (r = 0.271, P = 0.000; r = 0.315, P = 0.000, respectively). CONCLUSIONS: Sonotubometry, impedance, TTAG, and TMM have their own advantages and disadvantages. In clinical practice, the appropriate ET function test should be chosen on the basis of the patient's specific condition.

The utility of acoustic pharyngometry and rhinometry in pediatric obstructive sleep apnea syndrome.

OBJECTIVE: Our objective was to evaluate the usefulness of acoustic pharyngometry and rhinometry in assessing obstructive sleep apnea (OSA) syndrome in children. PATIENTS/METHODS: Patients who were hospitalized for polysomnography underwent acoustic pharyngometry and rhinometry in sitting and supine positions to measure anatomical (pharyngeal and nasopharyngeal) volumes and collapsibility characteristics (reduction of pharyngeal volume, estimated pharyngeal compliance, and reduction of nasopharyngeal volume). RESULTS: In this study, we prospectively enrolled 103 children (median age, 10.4 years; 47 girls). Measures obtained from rhinometry correlated with height and were further height-normalized whereas measures obtained from pharyngometry did not correlate with height. Sleep apnea was ruled out in 51 subjects, while 52 children fulfilled OSA criteria (35 with obstructive apnea-hypopnea index ≥ 2 and < 5.h-1 [mild] and 17 with an index ≥ 5). The three groups differed on the z-score of BMI, the reduction of pharyngeal volume when supine, the estimated pharyngeal compliance and the supine normalized nasopharyngeal volume. These four factors linearly correlated with the apnea index even though children without OSA and mild OSA were found to be similar overall. A multivariate analysis with apnea index as the dependent variable and BMI z-score, neck circumference, mean pharyngeal area in supine position, estimated pharyngeal compliance and normalized nasopharyngeal volume as independent variables, showed that only BMI z-score and estimated compliance remained independent predictors of obstructive apnea (r2 value = 0.25, p < 0.0001). CONCLUSION: An increase in pharyngeal compliance is an independent risk factor of OSA syndrome in children; it can be measured using acoustic pharyngometry while awake.

Comparison of Pharyngeal Airway between Mandibular Setback Surgery Patients (Skeletal Class III) and Nonsurgery Patients (Skeletal Classes I and II).

PURPOSE: We investigated the pharyngeal airway dimensions and their correlations in patients who underwent mandibular setback surgery versus those who did not. MATERIALS AND METHODS: One hundred and sixty cephalometric radiographs (120 patients) were obtained from patients with three skeletal malocclusion classifications: Class I and Class II in the nonsurgery group and Class III in the surgery group (preoperative and postoperative cephalograms). The following dimensions were measured: nasopharyngeal airway (NOP), uvulopharyngeal airway (UOP), shortest distance from the posterior tongue to the pharyngeal wall (TOP), and distance from the epiglottis to the pharyngeal wall (EOP). Paired t test, one-way analysis of variance, and Pearson correlation coefficients were used for statistical analysis. RESULTS: Preoperatively, UOP and TOP of skeletal Class III patients (15.2 mm and 16.6 mm) were significantly larger than those of skeletal Class II (11.5 mm and 12 mm) and Class II (12.3 mm and 12.9 mm) patients, respectively. No differences were observed in EOP between the three skeletal patterns. The hyoid bone of Class III patients was significantly anterior to that of Class I/II patients. Furthermore, UOP had a moderate negative correlation with soft palate length. Postoperatively, no significant difference (UOP, TOP, EOP, soft palate width, and hyoid bone) was found between the skeletal classes. CONCLUSION: Preoperatively, UOP and TOP of skeletal Class III patients were significantly wider than those of skeletal Class I/II patients. Pre- and postoperatively, EOP did not exhibit significant differences among the three skeletal classifications. No differences were found in all postoperative pharyngeal airway dimensions between Class III patients and nonsurgery patients (Class I and Class II).

Nasal Delivery Devices: A Comparative Study on Cadaver Model.

Nasal nebulization is a more effective method of delivering topical medication than nasal spray. The purpose of this study was to assess the deposition patterns of nebulization in delivering topical agents to the nasal cavities in the human cadaveric model using a color-based method. We have compared these following nasal devices: single-dose vial irrigation, syringe-irrigation, common nasal spray, Spray-sol, MAD nasal, and Rinowash nasal douche. Endoscopic images were recorded at six anatomical regions prior to and following each nasal device application and four reviewers evaluated the amount of surface area staining. At the nasal vestibule, the blue dye distribution achieved with Spray-sol was more extensive than nasal sprays. At inferior turbinate and nasal cavity floor, single dose vial, syringe, MAD nasal, Spray-sol, and Rinowash demonstrated a greater extent of dye distribution than nasal spray. At the middle turbinate, the average score of both Spray-sol and MAD nasal was significantly higher than other nasal investigated devices. At the nasopharynx, Spray-sol nebulization covers a surface significantly greater than other devices. Compared to traditional sprays, Spray-sol and MAD nasal provided a more effective method of delivering topical agents to the deeper and higher portions of the nasal cavities.

Choanal atresia and stenosis: Development and diseases of the nasal cavity.

Proper craniofacial development in vertebrates depends on growth and fusion of the facial processes during embryogenesis. Failure of any step in this process could lead to craniofacial anomalies such as facial clefting, which has been well studied with regard to its molecular etiology and cellular pathogenesis. Nasal cavity invagination is also a critical event in proper craniofacial development, and is required for the formation of a functional nasal cavity and airway. The nasal cavity must connect the nasopharynx with the primitive choanae to complete an airway from the nostril to the nasopharynx. In contrast to orofacial clefts, defects in nasal cavity and airway formation, such as choanal atresia (CA), in which the connection between the nasal airway and nasopharynx is physically blocked, have largely been understudied. This is also true for a narrowed connection between the nasal cavity and the nasopharynx, which is known as choanal stenosis (CS). CA occurs in approximately 1 in 5,000 live births, and can present in isolation but typically arises as part of a syndrome. Despite the fact that CA and CS usually require immediate intervention, and substantially affect the quality of life of affected individuals, the etiology and pathogenesis of CA and CS have remained elusive. In this review I focus on the process of nasal cavity development with respect to forming a functional airway and discuss the cellular behavior and molecular networks governing this process. Additionally, the etiology of human CA is discussed using examples of disorders which involve CA or CS. This article is categorized under: Signaling Pathways > Cell Fate Signaling Comparative Development and Evolution > Model Systems Birth Defects > Craniofacial and Nervous System Anomalies.

Effect of Nasal Valve Shape on Downstream Volume, Airflow, and Pressure Drop: Importance of the Nasal Valve Revisited.

OBJECTIVES: The relative importance of the nasal valve relative to the remainder of the nasal airway remains unknown. The goal of this article was to objectively measure the shape of the nasal inlet and its effect on downstream airflow and nasal cavity volume using a physical model and a physiologic flow model. METHODS: A patient who had isolated nasal valve surgery and had pre- and postoperative computed tomography scans available for analysis was studied. Nasal inlet shape measurements, computational fluid dynamics, and nasal volume analysis were performed using the computed tomography data. In addition, a physical model was used to determine the effect of nasal obstruction on downstream soft tissue. RESULTS: The postoperative shape of the nasal inlet was improved in terms of length and degree of tortuosity. Whereas the operated-on region at the nasal inlet showed an only 25% increase in cross-sectional area postoperatively, downstream nonoperated sites in the nasal cavity revealed increases in area ranging from 33% to 51%. Computational fluid dynamics analysis showed that airway resistance decreased by 42%, and pressure drop was reduced by 43%. Intraluminal mucosal expansion was found with nasal obstruction in the physical model. CONCLUSION: By decreasing the degree of bending and length at the nasal valve, inspiratory downstream nonoperated sites of the nasal cavity showed improvement in volume and airflow, suggesting that the nasal valve could play an oversized role in modulating the aerodynamics of the airway. This was confirmed with the physical model of nasal obstruction on downstream mucosa.

Clinical application of MRI-respiratory gating technology in the evaluation of children with obstructive sleep apnea hypopnea syndrome.

The objective of the present study was to investigate the clinical application of magnetic resonance imaging (MRI)-respiratory gating technology for assessing illness severity in children with obstructive sleep apnea hypopnea syndrome (OSAHS).MRI-respiratory gating technology was used to scan the nasopharyngeal cavities of 51 children diagnosed with OSAHS during 6 respiratory phases. Correlations between the ratio of the area of the adenoid to the area of the nasopalatine pharyngeal cavity (Sa/Snp), with the main indexes of polysomnography (PSG), were analyzed. Receiver operator characteristic (ROC) curve and Kappa analysis were used to determine the diagnostic accuracy of Sa/Snp in pediatric OSAHS.The Sa/Snp was positively correlated with the apnea hypopnea index (AHI) (P < .001) and negatively correlated with the lowest oxygen saturation of blood during sleep (LaSO2) (P < .001). ROC analysis in the 6 respiratory phases showed that the area under the curve (AUC) of the Sa/Snp in the end-expiratory phase was the largest (0.992, P < .001), providing a threshold of 69.5% for the diagnosis of severe versus slight-moderate OSAHS in children. Consistency analysis with the AHI showed a diagnosis accordance rate of 96.0% in severe pediatric OSAHS and 96.2% in slight-moderate pediatric OSAHS (Kappa = 0.922, P < .001).Stenosis of the nasopalatine pharyngeal cavity in children with adenoidal hypertrophy was greatest at the end-expiration phase during sleep. The end-expiratory Sa/Snp obtained by a combination of MRI and respiratory gating technology has potential as an important imaging index for diagnosing and evaluating severity in pediatric OSAHS.

Study on the Short-Time Remolding of Upper Airway After Uvulopalatopharyngoplasty.

OBJECTIVE: To verify the short-time remolding of upper airway in patients diagnosed with obstructive sleep disordered breathing after Uvulopalatopharyngoplasty (UPPP). METHODS: Twenty-one male adult patients aged 27 to 52 years followed up ranged from preoperation to 6 months after the operation. Lateral cephalometric radiographs (conventional and when pronouncing "i") were obtained 2 weeks preoperatively, 3 days postoperatively, and 1, 2, 3, 6 months after the surgery. The anterolateral diameters of different levels of upper airway and parameters of hyoid position of the patients were then measured. SAS 8.02 was used to analyze the differences by time. RESULTS: The study illustrated that the UPPP major affected the velopharyngeal and glossopharyngeal areas: parameters wane (P <0.05). On the other hand, UPPP leaded to the decline and retreat of hyoid. Most of the parameters remained metabolic. The nasopharynx kept statical (P >0.05) while the velopharyngeal parameters were increasing (P <0.05). The glossopharyngeal parameters increased in the first month after UPPP (P <0.05), while hypopharyngeal parameters underwent decline since 2 months after UPPP (P <0.05). The hyoid obtained decline and retreat (P <0.05) overall, while it endured a short-time climb in the first month after UPPP (P <0.05). CONCLUSION: Short-time upper airway remolding after UPPP existed.

High-flow nasal cannula therapy for adult patients.

High-flow nasal cannula (HFNC) oxygen therapy has several physiological advantages over traditional oxygen therapy devices, including decreased nasopharyngeal resistance, washing out of the nasopharyngeal dead space, generation of positive pressure in the pharynx, increasing alveolar recruitment in the lungs, humidification of the airways, increased fraction of inspired oxygen and improved mucociliary clearance. Recently, the use of HFNC in treating adult critical illness patients has significantly increased, and it is now being used in many patients with a range of different disease conditions. However, there are no established guidelines to direct the safe and effective use of HFNC for these patients. This review article summarizes the available published literature on the positive physiological effects, mechanisms of action, and the clinical applications of HFNC, compared with traditional oxygen therapy devices. The available literature suggests that HFNC oxygen therapy is an effective modality for the early treatment of critically adult patients.

Case Study: Imaging of Apnea Termination in a Patient with Obstructive Sleep Apnea during Natural Sleep.

ABSTRACT: A 55-year-old woman who presented to the sleep clinic with severe sleep apnea (OSA) (apnea-hypopnea index [AHI] 62) and excessive somnolence (Epworth Sleepiness Scale score 18/24), was imaged with MRI using the Spatial Modulation of Magnetization tagging sequence awake and asleep to visualize upper airway tissue movement. Awake quiet breathing resulted in minimal movement of upper airway tissues. Asleep sequences taken during airway opening post-apnea demonstrated neck extension, mandibular advancement, and widespread tongue deformation accompanying contraction of genioglossus. At the end of the asleep image sequence, the nasopharyngeal airway had a cross-sectional area larger than during quiet breathing awake and there was antero-lateral movement in the lateral walls. In conclusion, the airway responds to apnea by widespread contraction of the genioglossus, followed by mandibular advancement and neck extension. All these maneuvers stabilize and open the airway.

Impact of nasal septal perforations of varying sizes and locations on the warming function of the nasal cavity: A computational fluid-dynamics analysis of 5 cases.

Patients with a nasal septal perforation often exhibit symptoms associated with disturbed airflow, which can have an adverse effect on the warming function of the nasal cavity. The impact of this effect is not fully understood. The warming function is an important factor in the maintenance of nasal physiology. We conducted a study to investigate the impact of septal perforations of various sizes and locations on the warming function during inspiration in 5 patients-3 men and 2 women, aged 25 to 47 years. Three-dimensional computed tomography and computational fluid dynamics were used to model the flux of communication and temperature, and differences among patients were compared. All 5 patients exhibited an impairment of their nasal warming function. As the size of the perforation increased, the flux of communication increased and the warming function decreased. Perforations located in an anterior position were associated with greater damage to the warming function than those in a posterior position. In patients with a large or anteriorly located perforation, airflow temperature in the nasopharynx was decreased. Our findings suggest that septal perforations not only induce airflow disturbance, but they also impair the nasal warming function. Further analysis of warming function is necessary to better explore flow mechanisms in patients with structural abnormalities.

Upper airway morphology in Down Syndrome patients under dexmedetomidine sedation / Morfologia das vias aéreas superiores em pacientes com síndrome de Down sob sedação com dexmedetomidina

Abstract Background and objectives: Children with Down Syndrome are vulnerable to significant upper airway obstruction due to relative macroglossia and dynamic airway collapse. The objective of this study was to compare the upper airway dimensions of children with Down Syndrome and obstructive sleep apnea with normal airway under dexmedetomidine sedation. Methods: IRB approval was obtained. In this retrospective study, clinically indicated dynamic sagittal midline magnetic resonance images of the upper airway were obtained under low (1 mcg/kg/h) and high (3 mcg/kg/h) dose dexmedetomidine. Airway anteroposterior diameters and sectional areas were measured as minimum and maximum dimensions by two independent observers at soft palate (nasopharyngeal airway) and at base of the tongue (retroglossal airway). Results and conclusions: Minimum anteroposterior diameter and minimum sectional area at nasopharynx and retroglossal airway were significantly reduced in Down Syndrome compared to normal airway at both low and high dose dexmedetomidine. However, there were no significant differences between low and high dose dexmedetomidine in both Down Syndrome and normal airway. The mean apnea hypopnea index in Down Syndrome was 16 ± 11. Under dexmedetomidine sedation, children with Down Syndrome and obstructive sleep apnea when compared to normal airway children show significant reductions in airway dimensions most pronounced at the narrowest points in the nasopharyngeal and retroglossal airways.

Resumo Justificativa e objetivos: As crianças com síndrome de Down (SD) são vulneráveis à obstrução significativa das vias aéreas superiores devido à macroglossia relativa e ao colapso dinâmico das vias aéreas. O objetivo deste estudo foi comparar as dimensões das vias aéreas superiores de crianças com SD e apneia obstrutiva do sono (AOS) com vias aéreas normais (VAN) sob sedação com dexmedetomidina (DEX). Métodos: Aprovação IRB foi obtida. Neste estudo retrospectivo, imagens clinicamente indicadas de ressonância magnética da dinâmica das vias aéreas superiores em plano sagital na linha média foram obtidas sob dose baixa (1 mcg/kg/h) e dose alta (3 mcg/kg/h) de DEX. Os diâmetros anteroposteriores das vias aéreas e as áreas seccionais foram medidas como dimensões mínimas e máximas por dois observadores independentes, no palato mole (região nasofaríngea) e na base da língua (região retroglossal). Resultados e conclusões: O diâmetro mínimo anteroposterior e a área seccional mínima das regiões nasofaríngea e retroglossal estavam significativamente reduzidos na SD em comparação com VAN, tanto com a dose baixa quanto com a dose alta de DEX. Contudo, não houve diferenças significativas entre as doses baixa e alta de DEX em SD e VAN. A média do índice de apneia e hipopneia na SD foi de 16 ± 11. Sob sedação com DEX, as crianças com SD e AOS, quando comparadas com as crianças com VAN, apresentaram reduções significativas nas dimensões das vias aéreas, mais pronunciadas nos pontos mais estreitos das regiões nasofaríngea e retroglossal.

Upper airway morphology in Down Syndrome patients under dexmedetomidine sedation.

BACKGROUND AND OBJECTIVES: Children with Down Syndrome are vulnerable to significant upper airway obstruction due to relative macroglossia and dynamic airway collapse. The objective of this study was to compare the upper airway dimensions of children with Down Syndrome and obstructive sleep apnea with normal airway under dexmedetomidine sedation. METHODS: IRB approval was obtained. In this retrospective study, clinically indicated dynamic sagittal midline magnetic resonance images of the upper airway were obtained under low (1mcg/kg/h) and high (3mcg/kg/h) dose dexmedetomidine. Airway anteroposterior diameters and sectional areas were measured as minimum and maximum dimensions by two independent observers at soft palate (nasopharyngeal airway) and at base of the tongue (retroglossal airway). RESULTS AND CONCLUSIONS: Minimum anteroposterior diameter and minimum sectional area at nasopharynx and retroglossal airway were significantly reduced in Down Syndrome compared to normal airway at both low and high dose dexmedetomidine. However, there were no significant differences between low and high dose dexmedetomidine in both Down Syndrome and normal airway. The mean apnea hypopnea index in Down Syndrome was 16±11. Under dexmedetomidine sedation, children with Down Syndrome and obstructive sleep apnea when compared to normal airway children show significant reductions in airway dimensions most pronounced at the narrowest points in the nasopharyngeal and retroglossal airways.

Effect of Nasal Obstruction on Continuous Positive Airway Pressure Treatment: Computational Fluid Dynamics Analyses.

OBJECTIVE: Nasal obstruction is a common problem in continuous positive airway pressure (CPAP) therapy for obstructive sleep apnea and limits treatment compliance. The purpose of this study is to model the effects of nasal obstruction on airflow parameters under CPAP using computational fluid dynamics (CFD), and to clarify quantitatively the relation between airflow velocity and pressure loss coefficient in subjects with and without nasal obstruction. METHODS: We conducted an observational cross-sectional study of 16 Japanese adult subjects, of whom 9 had nasal obstruction and 7 did not (control group). Three-dimensional reconstructed models of the nasal cavity and nasopharynx with a CPAP mask fitted to the nostrils were created from each subject's CT scans. The digital models were meshed with tetrahedral cells and stereolithography formats were created. CPAP airflow simulations were conducted using CFD software. Airflow streamlines and velocity contours in the nasal cavities and nasopharynx were compared between groups. Simulation models were confirmed to agree with actual measurements of nasal flow rate and with pressure and flow rate in the CPAP machine. RESULTS: Under 10 cmH2O CPAP, average maximum airflow velocity during inspiration was 17.6 ± 5.6 m/s in the nasal obstruction group but only 11.8 ± 1.4 m/s in the control group. The average pressure drop in the nasopharynx relative to inlet static pressure was 2.44 ± 1.41 cmH2O in the nasal obstruction group but only 1.17 ± 0.29 cmH2O in the control group. The nasal obstruction and control groups were clearly separated by a velocity threshold of 13.5 m/s, and pressure loss coefficient threshold of approximately 10.0. In contrast, there was no significant difference in expiratory pressure in the nasopharynx between the groups. CONCLUSION: This is the first CFD analysis of the effect of nasal obstruction on CPAP treatment. A strong correlation between the inspiratory pressure loss coefficient and maximum airflow velocity was found.