Primary site identification in children with OSA

Study Objectives: Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The identification of the primary site of OSA is essential to determine treatment strategy. This study aimed to establish computational fluid dynamics (CFD) analysis for determining the clinical severity of OSA and the primary site of OSA. Methods: Twenty children (mean age, 6 years) were divided into OSA and control groups according to their apnea hypopnea index. Three-dimensional airways were constructed from computed tomography data. The pharyngeal airway morphology and the pressure and velocity of the upper airway were evaluated using CFD analysis. Results: The maximum velocity and pressure of the upper airway in the OSA group were significantly correlated with the severity of OSA (rs = 0.741, P < 0.001; rs = 0.653, P = 0.002). A velocity higher than 12 m/s indicated the primary site of OSA. In addition, we found that the primary site of OSA is not necessarily the same as the collapsible conduit site. Conclusions: CFD analysis allows both the evaluation of the disease severity of OSA and the identification of the primary site of OSA in children. The primary site of OSA is not necessarily the same as the collapsible conduit site; therefore, CFD analysis can be used to identify the appropriate intervention for treating OSA

Evaluation of Pharyngeal Airway in Acromegaly

Objectives: Perioperative airway management may be particularly challenging in patients with acromegaly undergoing trans‐sphenoidal pituitary surgery (TSS). Management for airway obstruction is required prior to pituitary surgery to minimize perioperative hypoxia. The purpose of this retrospective study was to evaluate airway obstruction by simulation of computational fluid dynamics (CFD) using computed tomography (CT) images in patients who had undergone TSS. Methods: CT images of the nasopharyngeal airways of patients with acromegaly (n = 5) or nonfunctional pituitary adenoma (n = 6) undergoing TSS from April 2012 to January 2017 were used to construct these airways in three dimensions. Estimated airflow pressure and velocity in the retropalatal airway (RA), oropharyngeal airway (OA), and hypopharyngeal airway (HA) were simulated using CFD. Results: Estimated pharyngeal airflow pressure in the HA, OA, and RA was significantly greater in patients with acromegaly than in those with nonfunctional pituitary adenomas whereas the estimated pharyngeal airflow velocity was significantly impaired only in the RA of patients with acromegaly. Minimum postoperative SpO2 both within 3 hours and from 3 to 12 hours after the end of anesthesia was significantly lower in the patients with acromegaly. Additionally, estimated volume of tongue and pharyngeal airflow pressure in the HA, OA, and RA correlated with minimum postoperative SpO2. Conclusion: Pharyngeal airflow pressure estimated from CT images is high in patients with acromegaly, and these values correlate with postoperative minimum values for SpO2. Preoperative evaluation of CT images by CFD can predict difficulty in airway management and perioperative hypoxia

High-temperature thermoelectric properties of the double-perovskite ruthenium oxide (Sr1−x_{1-x}Lax_x)2_2ErRuO6_6

We have prepared polycrystalline samples of (Sr$_{1-x}$La$_x$)$_2$ErRuO$_6$ and (Sr$_{1-x}$La$_x$)$_2$YRuO$_6$, and have measured the resistivity, Seebeck coefficient, thermal conductivity, susceptibility and x-ray absorption in order to evaluate the electronic states and thermoelectric properties of the doped double-perovskite ruthenates. We have observed a large Seebeck coefficient of -160 $\mu$V/K and a low thermal conductivity of 7 mW/cmK for $x$=0.1 at 800 K in air. These two values are suitable for efficient oxide thermoelectrics, although the resistivity is still as high as 1 $\Omega$cm. From the susceptibility and x-ray absorption measurements, we find that the doped electrons exist as Ru$^{4+}$ in the low spin state. On the basis of the measured results, the electronic states and the conduction mechanism are discussed.Comment: 6 pages, 4 figures, J. Appl. Phys. (accepted

Evaluation of the effect of oral appliance treatment on upper-airway ventilation conditions in obstructive sleep apnea using computational fluid dynamics

Objective: To evaluate the effect of oral appliance (OA) treatment on upper-airway ventilation conditions in patients with obstructive sleep apnea (OSA) using computational fluid dynamics (CFD). Methods: Fifteen patients received OA treatment and underwent polysomnography (PSG) and computed tomography (CT). CT data were used to reconstruct three-dimensional models of nasal and pharyngeal airways. Airflow velocity and airway pressure measurements at inspiration were simulated using CFD. Results: The apnea–hypopnea index (AHI) improved from 23.1 to 10.1 events/h after OA treatment. On CFD analysis, airflow velocity decreased at the retropalatal and epiglottis-tip levels, while airway pressure decreased at the retropalatal, uvular- and epiglottis-tip levels. The AHI of patients with OSA before OA treatment was correlated with airway pressure at the epiglottis-tip level. Discussion: Treatment with OA improved the ventilation conditions of the pharyngeal airway and AHI. Results of CFD analysis of airway pressure and airflow velocity helped determine the severity and ventilatory impairment site of OSA, respectively

Effect of adenoids and tonsil tissue on pediatric obstructive sleep apnea severity determined by computational fluid dynamics

Study objective: Obstructive sleep apnea (OSA) is a respiratory disorder caused by the obstruction of the upper airway during sleep. The most common cause of pediatric OSA is adenotonsillar hypertrophy. Adenotonsillectomy is the first-line treatment for pediatric OSA; however, OSA persists in a significant number of patients due, in part, to the method of evaluating enlarged adenoids and tonsil tissue (AT). The reason for these effects on OSA severity is not clear. This study aimed to establish a method to diagnose the need for adenoidectomy or tonsillectomy. Methods: Twenty-seven Japanese children (mean age 6.6 years) participated in this study, undergoing polysomnography and computed tomography examination. Pharyngeal airway morphology (AT size, volume, and cross-sectional area [CSA]) and pressure on the upper airway were evaluated at each site using computational fluid dynamic analysis. Results: Apnea hypopnea index (AHI) showed a strong linear association with maximum negative pressure (Pmax) (AHI = -0.055* Pmax -1.326, R2 = 0.805). The relationship between minimum CSA (CSAmin) and Pmax was represented by an inversely proportional fitted curve (Pmax = -4797/ CSAmin -5.1, R2 = 0.507). The relationship between CSAmin and AHI was also represented by an inversely proportional fitted curve (AHI = 301.6/ CSAmin 1.22, R2 = 0.680). Pmax greatly increased if CSAmin became ≤ 30 mm2. The negative pressure of each site increased when CSA measured ≤ 50 mm2. Conclusions: In children, when the CSA for each site is ≤ 50 mm2, AHI is likely to be elevated, and the patient may require tonsillectomy or adenoidectomy

Simultaneous Evaluation of Three-Dimensional Lip Kinetics and Tongue Pressure during Swallowing

Objectives: The purpose of this study was to evaluate the amount of lip movement and simultaneous tongue pressure changes on an artificial palatal plate during swallowing. Methods: Subjects were 9 healthy males (25.4 ± 2.1 years of age). Three-dimensional lip movement was measured by a wireless optoelectronic system, and tongue pressure was simultaneously recorded by a sensor sheet attached to the incisive papilla of an artificial palatal plate. Reflective markers were attached to the right and left corners of the mouth to measure the distance between them. All subjects were instructed to swallow 5 mL and 20 mL samples of water at will. The maximum change of distance between the corners of mouth, the maximum tongue pressure, and the time interval between the two maxima (lip-tongue interval) were calculated. Wilcoxon’s test was used to detect significant differences in these measurements between the two volumes. Results: Maximum tongue pressure did not differ significantly between swallowed volumes. The maximum change of distance between the corners of mouth was larger and the lip-tongue interval was significantly shorter with the larger volume. Conclusions: We suggest that swallowing a larger volume is accomplished by larger lip movement rather than larger tongue movement. These results indicate that lip movement during swallowing can be evaluated objectively

Relationships between nasal resistance, adenoids, tonsils, and tongue posture and maxillofacial form in Class II and Class III children

Introduction: The purpose of this study was to clarify the relationships between upper airway factors (nasal resistance, adenoids, tonsils and tongue posture) and maxillofacial form in Class II and III children Methods: Sixty-four subjects (mean age, 9.3 years) with malocclusion were divided into Class II and Class III groups by ANB angle. Nasal resistance was calculated using computational fluid dynamics from cone-beam computed tomography (CBCT) data. Adenoids, tonsils and tongue posture were evaluated in CBCT images. The groups were compared using Mann-Whitney U-tests and Student t-tests. Spearman’s rank test assessed the relationships between upper airway factors and maxillofacial form. Results: Nasal resistance of the Class II group was significantly larger than that of the Class III group (P = 0.005). Nasal resistance of the Class II group was significantly correlated with inferior tongue posture (P < 0.001), and negatively correlated with intermolar width (P = 0.028). Tonsil size of the Class III group was significantly correlated with anterior tongue posture (P < 0.001) and mandibular incisor anterior position (P = 0.007). Anterior tongue posture of the Class III group was significantly correlated with mandibular protrusion. Conclusions: The relationships of upper airway factors differed between Class II and Class III children

Does rapid maxillary expansion improve nasal airway obstruction? A computer fluid dynamics study in patients with nasal mucosa hypertrophy and obstructive adenoids

Introduction: Rapid maxillary expansion (RME) expands the maxillary dentition laterally and improves nasal airway obstruction. However, the incidence of nasal airway obstruction improvement following RME is approximately 60%. This study aimed to clarify the beneficial effects of RME on nasal airway obstruction in specific pathologic nasal airway diseases (nasal mucosa hypertrophy and obstructed adenoids) using computer fluid dynamics (CFD). Methods: Sixty subjects (21 boys, mean age 9.1 years) were divided into three groups according to their nasal airway condition (control, nasal mucosa hypertrophy, and obstructed adenoids), and those requiring RME had cone‐ beam computed tomography (CBCT) images taken before and after RME. CBCT data were used to evaluate the nasal airway ventilation condition (pressure) using CFD and measure the cross-sectional area (CSA) of the nasal airway. Results: The CSA of the nasal airway significantly increased after RME in all three groups. The pressures in the control and nasal mucosa groups significantly reduced after RME but did not change significantly in the adenoid group. The incidence of improvement in nasal airway obstruction in the control, nasal mucosa, and adenoid groups was 90%, 31.6%, and 23.1%, respectively. Conclusions: The incidence of improvement in nasal airway obstruction after RME depends on the nasal airway condition (nasal mucosa hypertrophy and obstructed adenoids). In patients with non-pathologic nasal airway conditions, the obstruction may be sufficiently improved with RME. Furthermore, RME may be effective, to some extent, in treating nasal mucosa hypertrophy. However, RME was not effective in patients with nasal airway obstruction due to obstructed adenoids