• Journal of Biomedical Engineering Research
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• v.33 no.4
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• pp.177-183
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• 2012

The inspiratory flow rate of a human is changed with the amount of the workload. The flow characteristic is affected by the inspiratory flow rate. In the flow field of airway, the both of turbulence intensity and secondary flow affect the deposition pattern of particles which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The relatively inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. The low Reynolds number k-${\omega}$ turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the turbulence kinetic energy and secondary flow intensity increase in airway. On the other hand, the area of recirculation zone is smaller.

• Journal of The Korean Dental Society of Anesthesiology
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• v.13 no.3
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• pp.127-131
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• 2013

We experienced failed airway management in a patient who had partial mandibulectomy and reconstruction with free-flap. 40 year-old man (height: 164 cm, body weight: 59 kg) with malignant melanoma on #38 tooth area of mandibular body was scheduled for partial mandibulectomy and reconstruction with free flap. Approximately fifteen-hours after surgery, the patient was extubated without complication. Seven hours after extubation, we experienced respiratory failure andfailed airway managementdue to airway edema and neck. We failed orotracheal intubation with direct laryngoscopy andlaryngeal mask airway, thus we tried tracheostomy but the patient was hypoxic state for more than 30 minutes. The patient had got hypoxic brain damage in whole cerebral cortex and basal ganglia. We should have the policy of airway management of the patients who have massive oro-maxillo-facial surgery and all medical personnel who treat these patients should be educated the policy and airway management methods.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.5
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• pp.443-448
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• 2015

Obstructive sleep apnea (OSA) is a syndrome characterized by the repetitive episodic collapse of the upper airway. Maxillomandibular advancement surgery is one of the most effective surgical treatment methods in treating obstructive sleep apnea. The advancement of both maxill and mandible can enlarge the cross-sectional areas and volumes of the postero-superior airway. The purpose of this study is to analyze flow patterns in the upper airway before and after maxillomandibular advancement surgery. Here, we analyzed flow phenomena of inspiration and expiration to prevent obstructive sleep apnea patient from happening side effect. Modeling of the upper airway carried out from clinical CT scanned images. We used time-dependent values for boundary condition. CFD analyses were performed and evaluated section of minimum area (SMA), compared with patient inside upper airway before and after maxillomandibular advancement surgery in SMA, and negative pressure effects. The study showed the greatest enlargment of the section of minimum cross-sectional area. Moreover, the velocity and the negative airway pressure were decreased. According to the result of this study, the maxillomandibular advancement surgery stabilizes the airflow in the postero-superior airway of OSA patients.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.1-11
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• 2021

The purpose of this study is to investigate factors influencing the upper airway dimensions in skeletal Class II children and adolescents. In total, 67 patients were selected. Airway volume and minimal cross-sectional area were three-dimensionally assessed. Craniofacial morphology and skeletal maturity were assessed on generated two-dimensional cephalograms. The measurements were analyzed using Mann-Whitney test, one-way ANOVA, Pearson's correlation, and multiple regression analysis. Upper airway dimensions were significantly smaller in pre-peak stage group, and positively associated with age. Anterior facial height and age were the most relevant factors for airway volume. Mandibular width and age were the most relevant factors for minimal cross-sectional area. Upper airway dimensions were significantly associated with age, skeletal maturity and craniofacial morphology in all three planes.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.33.1-33.11
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• 2018

Background: Bimaxillary orthognathic surgery with maxillomandibular setback is often accompanied by changes in airway space. We analyzed the changes in airway space before and after surgery and assessed their association with obstructive sleep apnea. Methods: This study is based on the cohort of 13 adult patients (9 males, 4 females, average age 23.85 years) who underwent bimaxillary orthognathic surgery with maxillomandibular setback. We performed computed tomography and portable polysomnography before and after the surgery to assess changes in airway space and Apnea-Hypopnea Index (AHI) values (total, supine, non-supine). Results: The oropharyngeal airway volume decreased by 29% after the surgery, which was statistically significant (p < .05). The upper airway volume and hypopharyngeal airway volume were decreased, but not significantly (4 and 19%, respectively). The changes in airway surface area were statistically significant at all levels examined (p < .05). Changes in the maximum anteroposterior width of the airway were also significant at all levels (p < .05). However, the changes in maximum lateral width were only statistically significant at C2 level (p < .05). AHI values were increased after the surgery but not significantly at any position. Conclusions: Although bimaxillary surgery with maxillomandibular setback significantly reduces the airway space, it does not affect AHI values or induce obstructive sleep apnea.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.2
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• pp.157-161
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• 2001

The purpose of this study cephalometrically evaluated changes in the posterior airway space for patients with obstructive sleep apnea syndrome(OSAS) before and after surgical advancement of the maxilla and mandible. The change in calculated airway resistance was correlated with the respiratory disturbance index(RDI). Twenty cephalometric radiographs were traced before and after surgery to determine the posterior airway area and calculate resistance. Polysomnograms of each patient were obtained before and after surgery. All patients had a decrease in calculated airflow resistance in the airway. The mean amount of resistance was 865.15 before surgery, decreasing to 192.65 after surgery (p<0.01). Eighty-five percent of the patients experienced improvement in their RDI. Reduction in the RDI appears to be due to an increase in the posterior airway space and decrease in flow resistance.

• The Korean Journal of Emergency Medical Services
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• v.25 no.2
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• pp.169-186
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• 2021

Purpose: This study aimed to analyze the data from public information disclosure about pre-hospital advanced airway management and identify the problem by considering domestic laws and guidelines. Methods: Data were collected between 2017 and 2018 and analyzed using SPSS 25.0. Then, the problems of the analysis results based on the relevant laws and practical guidelines were reviewed. Results: The review of domestic laws and practice guidelines revealed that ambulance nurses can implement supraglottic airway device only under the following three conditions: ① smart advanced life support pilot project area, ② trained to insert I-Gel, and ③ member of a special ambulance. In total, 21,574 cases of advanced airway management (endotracheal intubation: 2,428, I-Gel: 18,502, LMA : 499, KING AIRWAY: 144) were reported. In many cases, advanced airway management was performed by ambulance nurses who did not meet the above conditions, which was in violation of laws and guidelines. In addition, the prognosis of intubated patients was not followed up. Conclusion: The Korea National Fire Agency must stop all unlicensed medical practice by untrained, uneducated, and uncertified nurses and demand quality control programs for intubated patients.

• Journal of Digital Convergence
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• v.15 no.10
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• pp.307-314
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• 2017

In this study, a minimum amount of the vertical occlusion was secured differently in each type of mandibular advance devices snoring and Class I malocclusion patients wore these devices. This study analyzes, after the use of devices, a different amount of the vertical occlusion results in a change of the area of upper airway by additional changes such as mandibular position, muscle changes, tongue position. The higher the vertical amount, the area of the upper airway was shown smaller, And if the patient's tongues was prevented from the distal movement, the area of the upper airway had increased, To reduce snoring, doctors should accurately diagnose patients' occlusal relationships and select a MAD snoring that is appropriate for the occlusion. The dental technician who builds the selected device should also consider design settings such as the amount of vertical occlusion, the finish lines, and the thickness of the device to increase the effectiveness of the device.

• The korean journal of orthodontics
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• v.40 no.2
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• pp.66-76
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• 2010

Objective: Obstructive sleep apnea (OSA) is a common disorder which is characterized by a recurrence of entire or partial collapse of the pharyngeal airway during sleep. A given tidal volume must traverse the soft tissue tube structure of the upper airway, so the tendency for airway obstruction is influenced by the geometries of the duct and characteristics of the airflow in respect to fluid dynamics. Methods: Individualized 3D FEA models were reconstructed from pretreatment computerized tomogram images of three patients with obstructive sleep apnea. 3D computational fluid dynamics analysis was used to observe the effect of airway geometry on the flow velocity, negative pressure and pressure drop in the upper airway at an inspiration flow rate of 170, 200, and 230 ml/s per nostril. Results: In all 3 models, large airflow velocity and negative pressure were observed around the section of minimum area (SMA), the region which narrows around the velopharynx and oropharynx. The bigger the Out-A (outlet area)/ SMA-A (SMA area) ratio, the greater was the change in airflow velocity and negative pressure. Conclusions: Pressure drop meaning the difference between highest pressure at nostril and lowest pressure at SMA, is a good indicator for upper airway resistance which increased more as the airflow volume was increased.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.27.1-27.9
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• 2020

Background: Mandibular setback surgery can change the position of the mandible which improves occlusion and facial profile. Surgical movement of the mandible affects the base of the tongue, hyoid bone, and associated tissues, resulting in changes in the pharyngeal airway space. The aim of this study was to analyze the 3-dimensional (3D) changes in the hyoid bone and tongue positions and oropharyngeal airway space after mandibular setback surgery. Methods: A total of 30 pairs of cone-beam computed tomography (CBCT) images taken before and 1 month after surgery were analyzed by measuring changes in the hyoid bone and tongue positions and oropharyngeal airway space. The CBCT images were reoriented using InVivo 5.3 software (Anatomage, San Jose, USA) and landmarks were assigned to establish coordinates in a three-dimensional plane. The mean age of the patients was 21.7 years and the mean amount of mandibular setback was 5.94 mm measured from the B-point. Results: The hyoid bone showed significant posterior and inferior displacement (P < 0.001, P < 0.001, respectively). Significant superior and posterior movements of the tongue were observed (P < 0.05, P < 0.05, respectively). Regarding the velopharyngeal and glossopharyngeal spaces, there were significant reductions in the volume and minimal cross-sectional area (P < 0.001). The anteroposterior and transverse widths of the minimal cross-sectional area were decreased (P < 0.001, P < 0.001, respectively). In addition, the amount of mandibular setback positively correlated with the amount of posterior and inferior movement of the hyoid bone (P < 0.05, P < 0.05, respectively). Conclusion: There were significant changes in the hyoid bone, tongue, and airway space after mandibular setback surgery.