• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.2
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• pp.135-138
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• 2017

Intraoperative airway obstruction is perplexing to anesthesiologists because the patient may fall into danger rapidly. A 74-year-old woman underwent an emergency incision and drainage for a deep neck infection of dental origin. She was orally intubated with a 6. 0 mm internal diameter reinforced endotracheal tube by video laryngoscope using volatile induction and maintenance anesthesia (VIMA) with sevoflurane, fentanyl ($100{\mu}g$), and succinylcholine (75 mg). During surgery, peak inspiratory pressure increased from 22 to $38cmH_2O$ and plateau pressure increased from 20 to $28cmH_2O$. We maintained anesthesia because we were unable to access the airway, which was covered with surgical drapes, and tidal volume was delivered. At the end of surgery, we found a longitudinal fold inside the tube with a fiberoptic bronchoscope. The patient was reintubated with another tube and ventilation immediately improved. We recognized that the tube was obstructed due to dissection of the inner layer.

• Sleep Medicine and Psychophysiology
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• v.18 no.2
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• pp.63-66
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• 2011

It has been controversial whether upper airway resistance syndrome (UARS) is a distinct syndrome or not since it was reported in 1993. The International Classification of Sleep Disorders classified UARS under obstructive sleep apnea syndrome (OSAS) in 2005. UARS can be diagnosed when the apnea-hypopnea index (AHI) is fewer than 5 events per hour, the simultaneously calculated respiratory disturbance index (RDI) is more than 5 events per hour due to abnormal non-apneic non-hypopneic respiratory events accompanying respiratory effort related arousals (RERAs), and oxygen saturation is greater than 92% at termination of an abnormal breathing event. Although esophageal pressure measurement remains the gold standard for detecting subtle breathing abnormality other than hypopnea and apnea, nasal pressure transducer has been most commonly used. RERAs include phase A2 of cyclical alternating patterns (CAPs) associated with EEG changes. Symptoms of OSAS can overlap with UARS, but chronic insomnia tends to be more common in UARS than in OSAS and clinical symptoms similar with functional somatic syndrome are also more common in UARS. In this journal, diagnostic and clinical differences between UARS and OSAS are reviewed.

• Journal of Sleep Medicine
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• v.15 no.2
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• pp.48-54
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• 2018

Objectives: The aim of this study was to develop a predicting model for the optimal continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) patient with obesity by using a machine learning. Methods: We retrospectively investigated the medical records of 162 OSA patients who had obesity [body mass index (BMI) ≥ 25] and undertaken successful CPAP titration study. We divided the data to a training set (90%) and a test set (10%), randomly. We made a random forest model and a least absolute shrinkage and selection operator (lasso) regression model to predict the optimal pressure by using the training set, and then applied our models and previous reported equations to the test set. To compare the fitness of each models, we used a correlation coefficient (CC) and a mean absolute error (MAE). Results: The random forest model showed the best performance {CC 0.78 [95% confidence interval (CI) 0.43-0.93], MAE 1.20}. The lasso regression model also showed the improved result [CC 0.78 (95% CI 0.42-0.93), MAE 1.26] compared to the Hoffstein equation [CC 0.68 (95% CI 0.23-0.89), MAE 1.34] and the Choi's equation [CC 0.72 (95% CI 0.30-0.90), MAE 1.40]. Conclusions: Our random forest model and lasso model ($26.213+0.084{\times}BMI+0.004{\times}$apnea-hypopnea index+$0.004{\times}oxygen$ desaturation index-$0.215{\times}mean$ oxygen saturation) showed the improved performance compared to the previous reported equations. The further study for other subgroup or phenotype of OSA is required.

• Archives of Craniofacial Surgery
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• v.18 no.4
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• pp.223-229
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• 2017

The beauty of the laryngeal mask is that it forms an air tight seal enclosing the larynx rather than plugging the pharynx, and avoid airway obstruction in the oropharynx. The goal of its development was to create an intermediate form of airway management face mask and endotracheal tube. Indication for its use includes any procedure that would normally involve the use of a face mask. The laryngeal mask airway was designed as a new concept in airway management and has been gaining a firm position in anesthetic practice. Despite wide spread use the definitive role of the laryngeal mask airway is yet to be established. In some situations, such as after failed tracheal intubation or in oral surgery its use is controversial. There are several unresolved issues, for example the effect of the laryngeal mask on regurgitation and whether or not cricoids pressure prevents placement of mask. We review the techniques of insertion, details of misplacement, and complications associated with use of the laryngeal mask. We then attempt to clarify the role of laryngeal mask in air way management during anesthesia, discussing the advantages and disadvantages as well as indications and contraindications of its use in oral and maxillofacial surgery.

• Tuberculosis and Respiratory Diseases
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• v.42 no.2
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• pp.218-225
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• 1995

Background: Airway resistance(Raw) is measured with the body plethysmograph by displaying the relationship between airflow and alveolar pressure($V/P_A$). If the resistance curve on $V/P_A$ tracing is curved or looped, the estimation of Raw is difficult. This study was designed to examine wheather there is any correlation between the shape of resistance curve and the clinical status and the pulmonary function of patients. Methods: The 146 pulmonary disease patients with increased Raw were included in this study. The shapes of resistance curves on $V/P_A$ tracing with body plethysmograph during quiet breathing were analyzed and compared with pulmonary function. Results: The results were as follows ; 1) The shapes of resistance curves were summarized in 5 categories; type 1: linear, type 2: ovoid, type 3: sigmoid, type 4: scoop, type 5: paisley. The type 3 except 1 case, type 4 and type 5 were found to have loop mainly in expiratory phase. 2) Although the shapes of resistance curves were not typical for specific disease, the resistance curves of acute disease tended to belong to type 1 or 2 and those of chronic airflow obstruction tended to belong to type 3, 4 or 5. But resistance curves of bronchial asthma and destructive lung with tuberculosis showed all types in proportion to degree of airflow obstruction or destruction of parenchyme. 3) In the cases of resistance curves going to type 5 rather than type 1 and those with looping, airflow obstuction tended to be severe and airway resistance and residual volume tended to increase. Conclusions: Analysis of resistance curve on $V/P_A$ tracing measuring airway resistance is helpful for judging degree of airflow obstruction and air trapping. Although the shape of resistance curve is not typical for specific disease, there is a close association between looping and airway obstruction.

• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.69-74
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• 2010

Obstructive sleep apnea syndrome is associated with significant cardiovascular morbidity and increased mortality. However, it was controversial whether obstructive sleep apnea syndrome could cause pulmonary hypertension. The controversy was resolved by several studies that have shown pulmonary hypertension in 20% to 40% of patients with obstructive sleep apnea syndrome without underlying other cardiopulmonary diseases and reductions in pulmonary arterial pressure in patients with obstructive sleep apnea syndrome after treatment with nocturnal continuous positive airway pressure. Recent studies provide strong evidence for endothelial dysfunction in obstructive sleep apnea syndrome and pulmonary hypertension. Endothelin-1 is a 21 amino acid peptide with diverse biologic activity such as highly potent vasoconstrictor and mitogen regulator that may play a key role in obstructive sleep ap-nea syndrome and pulmonary hypertension. Continuous positive airway pressure therapy is moderately effective in reducing pulmonary arterial pressure. Further researches are needed to assess the therapeutic efficacy of pharmacologic therapy with agents that inhibit the action of endothelin-1 in obstructive sleep apnea syndrome patients with pulmonary hypertension.

• Phonetics and Speech Sciences
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• v.4 no.3
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• pp.171-177
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• 2012

The purpose of this study was to investigate whether CPAP therapy was effective for reducing the degree of hypernasality in individuals with repaired cleft palate and whether the efficacy of CPAP therapy was maintained. Five individuals with cleft palate participated in an 8-week home-based CPAP program. Results from perceptual evaluation of hypernasality and nasalance scores before and after CPAP therapy and at the follow-up speech evaluation were compared. The results of the study showed that the responses of the CPAP therapy were various among individuals. Three individuals exhibited reductions in the degree of perceived hypernasality, while nasalance scores in all individuals decreased after the therapy. The results showed that the effect of CPAP therapy was generally maintained until approximately three months after the completion of CPAP therapy.

• The Korean Journal of Emergency Medical Services
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• v.17 no.3
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• pp.21-28
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• 2013

Purpose: The purpose of this study is to get basic user guidelines of safe and efficient bag-valve-mask application on patients having abnormal pathophysiological pulmonary conditions. Methods: This study was performed by pre-qualified 35 EMS junior and senior students. Participants were instructed to compress ambulatory bag randomly about half, one-third, one-fourth within different airway resistance and pulmonary compliance. Resultant tidal volume and pulmonary wedge pressures on RespiTranier monitor were analysed in relation to pulmonary physiologic index. Results: At least over half compression of bag guaranteed minimal tidal volume regardless of pulmonary conditions. There was no increase of pulmonary wedge pressure above the level of barotrauma on half compression at any pulmonary conditions. Conclusion: Assisted ventilation with ambulatory bag on patients with pathological pulmonary conditions should be over half compressed regardless of respiratory disease entity.

• Clinical and Experimental Pediatrics
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• v.63 no.1
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• pp.3-7
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• 2020

High-flow nasal cannula (HFNC) is a relatively safe and effective noninvasive ventilation method that was recently accepted as a treatment option for acute respiratory support before endotracheal intubation or invasive ventilation. The action mechanism of HFNC includes a decrease in nasopharyngeal resistance, washout of dead space, reduction in inflow of ambient air, and an increase in airway pressure. In preterm infants, HFNC can be used to prevent reintubation and initial noninvasive respiratory support after birth. In children, flow level adjustments are crucial considering their maximal efficacy and complications. Randomized controlled studies suggest that HFNC can be used in cases of moderate to severe bronchiolitis upon initial low-flow oxygen failure. HFNC can also reduce intubation and mechanical ventilation in children with respiratory failure. Several observational studies have shown that HFNC can be beneficial in acute asthma and other respiratory distress. Multicenter randomized studies are warranted to determine the feasibility and adherence of HFNC and continuous positive airway pressure in pediatric intensive care units. The development of clinical guidelines for HFNC, including flow settings, indications, and contraindications, device management, efficacy identification, and safety issues are needed, particularly in children.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.96-102
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• 2020

Oral cancer surgery changes the morphologic characteristics of the human upper airway. These changes can affect the flow patterns. In this study, computational fluid dynamics (CFD) simulations with transient solver were performed to numerically investigate the air flows in the human upper airways depending oral cancer surgery. 3D reconstructed models were obtained from 2D CT images of one patient. For the boundary condition, the realistic breathing cycle of human was applied. The hydraulic diameters of cross-sections for post-surgical model are changed greatly along streamwise direction, so these variations can cause higher wall shear stress and flow disturbance compared to pre-surgical model. The recirculation flows observed in the protruding region result in the relatively large pressure drop. These results can be helpful to understand the flow variations after resection surgery of oral cancer.