Seung-Kyu Chung

Effect of Endoscopic Sinus Surgery on Asthmatic Patients with Chronic Rhinosinusitis

There have been several reports on the effectiveness of endoscopic sinus surgery (ESS) in asthmatic patients with chronic rhinosinusitis. Whether ESS has a positive effect on the clinical course of asthma still remains controversial. There have been several subjective evaluations but few objective results. We performed a study to evaluate the effectiveness of ESS in 19 patients with asthma who underwent ESS for rhinosinusitis. The use of antiasthma medication and postoperative asthma symptoms was analyzed. Objective changes of pulmonary function tests were evaluated. There was a significant improvement in diurnal and nocturnal asthma symptoms. Improvements in asthma medication scores were also confirmed, and individual asthma symptoms (dyspnea, cough, wheezing, and sputum production) improved significantly. Despite a reduction in use of antiasthma medication after ESS, the parameters of the pulmonary function tests did not change. Both subjectively and objectively, it seems that ESS, when used to treat asthmatic patients with chronic rhinosinusitis, can play a significant role in the clinical improvement of asthma. (Otolaryngol Head Neck Surg 2001;124:99-104.)

Unsteady flow characteristics through a human nasal airway

Time-dependent characteristics of the flow in a human nasal airway constructed from the CT image of a healthy volunteer were investigated using a computational fluid dynamics (CFD) technique. To capture the time-varying nature of the flow as well as pressure and temperature fields, the large eddy simulation (LES) technique instead of the RANS (Reynolds Averaged Navier-Stokes) approach was adopted. To make the present analysis more relevant to a real human breathing cycle, the flow was designed to be induced by the pressure difference and the time-varying pressure at the end of trachea was described to reproduce the flow rate data from the measurement. Comparison of the present results with those of typical steady simulations showed that the difference in flow characteristics is magnified in the expiration phase. This fact may suggest that the inertial effect associated with unsteady flow is more important during the expiration period. Also, the fact that the distribution of the flow rate in a given cross-section of the airway changes significantly with time implies the importance of unsteady data for clinical decision. The wall shear stress was found to have relatively high values at the locations near nasopharynx and larynx but the magnitude changes with time during the whole respiratory cycle. Analysis of the temperature field showed that most of the temperature change occurs in the nasal cavity when the air is incoming and thus, the nasal cavity acts as a very efficient heat exchanger during an inspiration period.

Nasal airflow during respiratory cycle

Background Knowledge on the airflow patterns in the nasal cavity is essential to understanding the function of the nasal cavity. This study has attempted to observe the breath cycle of nasal airflow during respiration at rest. Methods We constructed a nasal cavity model by rapid prototyping using 1.25-mm-thick CT data and devised a piston pump driven by a cam, to simulate respiration at rest. The airflow was evaluated with particle image velocimetry and visualized in coronal reconstructed images. Results During the inspiration, a maximal velocity was observed at the valve area and the main stream occurred in the middle and superior airways. During the expiration, main stream was noted in the middle airway and was slow compared with the flow during inspiration. Vortexes were observed between inspiration and expiration. Conclusion This result widens our knowledge of nasal airflow and this technique will allow a more physiological understanding of nasal operations.

Digital particle image velocimetry studies of nasal airflow.

Understanding the properties of airflow in the nasal cavity is essential to understanding physiologic and pathologic aspects of nasal breathing. Many attempts have been made to evaluate nasal airflow patterns using the best possible analytical methods available at the time. Recently, digital particle image velocimetry (DPIV) and computational fluid dynamic methods have been applied to this area. Digital PIV is an experimental method used to evaluate airflow in an accurately reproduced transparent model of the nasal cavity. In this review, use of the DPIV procedure in the study of nasal airflow, airflow patterns in quiet respiration, and changes to airflow after modification of the nasal turbinates are reviewed, along with aspects of the DPIV technique and the future role of DPIV in this field of research.

Patient specific CFD models of nasal airflow: overview of methods and challenges.

Respiratory physiology and pathology are strongly dependent on the airflow inside the nasal cavity. However, the nasal anatomy, which is characterized by complex airway channels and significant individual differences, is difficult to analyze. Thus, commonly adopted diagnostic tools have yielded limited success. Nevertheless, with the rapid advances in computer resources, there have been more elaborate attempts to correlate airflow characteristics in human nasal airways with the symptoms and functions of the nose by computational fluid dynamics study. Furthermore, the computed nasal geometry can be virtually modified to reflect predicted results of the proposed surgical technique. In this article, several computational fluid mechanics (CFD) issues on patient-specific three dimensional (3D) modeling of nasal cavity and clinical applications were reviewed in relation to the cases of deviated nasal septum (decision for surgery), turbinectomy, and maxillary sinus ventilation (simulated- and post-surgery). Clinical relevance of fluid mechanical parameters, such as nasal resistance, flow allocation, wall shear stress, heat/humidity/NO gas distributions, to the symptoms and surgical outcome were discussed. Absolute values of such parameters reported by many research groups were different each other due to individual difference of nasal anatomy, the methodology for 3D modeling and numerical grid, laminar/turbulent flow model in CFD code. But, the correlation of these parameters to symptoms and surgery outcome seems to be obvious in each research group with subject-specific models and its variations (virtual- and post-surgery models). For the more reliable, patient-specific, and objective tools for diagnosis and outcomes of nasal surgery by using CFD, the future challenges will be the standardizations on the methodology for creating 3D airway models and the CFD procedures.

Inverted papilloma of the nasal cavity and paranasal sinuses: A Korean multicenter study

The study group for sinonasal tumors at the Korean Rhinologic Society analyzed the results of the Korean multicenter experience for sinonasal inverted papilloma (IP) surgeries.

Estrogen protects against 3-methylindole-induced olfactory loss

Olfactory dysfunction is among the first signs of Alzheimers disease (AD). Since estrogen therapy may mitigate the cognitive symptoms of AD, we determined whether 17beta-estradiol (E2) alters the olfactory discrimination performance of female rats exposed to the olfactotoxicant 3-methylindole (3-MI). Twelve ovariectomized rats received daily injections of E2 (1 mg/kg i.p.) in corn oil and 10 received daily injections of corn oil alone. Sensory testing occurred on a near-daily basis throughout a 10-week test period, midway in which a single injection of 3-MI was administered (300 mg/kg i.p.). On each pre- and post-3-MI test day, the rats were required to perform a series of successively more difficult odor discrimination tasks until one was reached where <80% performance was attained. The tasks were between the odor of a 10-4 v/v concentration of ethyl acetate (EA) and the odor of each of six different concentrations of butanol added to the EA (10-4, 10-4.5, 10-5.0, 10-5.5, 10-6.0, 10-6.5 v/v). Following 3-MI treatment, the performance of the E2-treated rats was found to be superior to that of the oil-treated rats and to return more quickly to the pre-3 MI baseline, suggesting that high doses of E2 mitigate 3-MI-induced smell loss in rats. Additional work is needed to determine the physiologic basis of this phenomenon.

Effects of single-sided inferior turbinectomy on nasal function and airflow characteristics.

Knowledge of airflow characteristics in the nasal cavity is essential to understanding the physiologic and pathologic aspects of nasal breathing. Airflows inside post-surgery models were investigated both experimentally and numerically to simulate the inferior turbinectomy. The left cavities of all three models are normal and right cavity is modified by (1) excision of the head of the inferior turbinate, (2) resection of the lower fifth of the inferior turbinate, and (3) resection of almost the entire inferior turbinate. Thin-slice CT (computed tomography) data (0.6mm deep) and meticulous refinement of the model surface by over a decade-long collaboration between engineers and an experienced ENT doctor resulted in the creation of sophisticated nasal cavity models. After numerical experiments and validation by comparison with the PIV results, the CFD code using the Reynolds stress turbulent model and variable temperature boundary condition on the mucosal wall was chosen as the proper numerical framework. Both global quantities (pressure drop, flow rate ratio, total wall heat transfer) and local changes (velocity, temperature, humidity, pressure gradient, and wall shear stress) were numerically investigated. The turbinectomy obviously altered the main stream direction. The flow rate in the upper airway near the olfactory slit decreased in models (1) and (3). This may weaken the olfactory function of the nose. Fluid and thermal properties that are believed to be related with physiology and prognosis are dependent on turbinate resection volume, position, and manner. Widening of the inferior airway does not always result in decreased flow resistance or wall heat transfer. The gains and losses of inferior turbinectomy were considered by analysis of the post-surgery model results. Nasal resistance was increased in model (1) due to sudden airway expansion. Nasal resistance increased and the wall heat transfer decreased in model (3) due to sudden airway expansion and excessive reduction of the mucosal wall surface area. Local shear stress and pressure gradient levels were increased in models (1) and (3).

Change of obstruction level during drug-induced sleep endoscopy according to sedation depth in obstructive sleep apnea.

We evaluated the change in upper airway collapse according to the depth of sedation during drug‐induced sleep endoscopy (DISE), as well as characteristics possibly associated with that change.

The correlation between pharyngeal narrowing and the severity of sleep-disordered breathing

OBJECTIVE: The aim of this study was to examine the correlation between the degree or shape of pharyngeal narrowing as observed during the Muller maneuver and the severity of sleep-disordered breathing (SDB). SUBJECTS AND METHODS: We enrolled 33 patients with SDB, and they underwent polysomnography (PSG). The degree of pharyngeal narrowing (grade I-IV) according to fiberoptic nasopharyngoscopy with the Muller maneuver (FNMM) and the shape of pharyngeal narrowing were evaluated at different anatomical levels. These variables were compared with the total apnea hypopnea index (AHI), the supine AHI, and the lateral AHI obtained by PSG. RESULTS: The retroglossal FNMM grades revealed significant correlation with total AHI (P = 0.030) and supine AHI (P = 0.012). The retropalatal FNMM grades were significantly correlated with lateral AHI (P = 0.020). The lateral-narrowing type at the retropalatal level is more significantly associated with higher total AHI compared with the anteroposterior-narrowing type (P = 0.010). CONCLUSION: The anatomic level and the degree of pharyngeal narrowing observed during FNMM revealed a correlation with the AHIs of different sleeping positions.