Endovenous radiofrequency ablation using a new bipolar electrode in a canine model: a new endovenous radiofrequency electrode

Purpose@#This study aimed to determine the effectiveness and safety of a newly developed endovenous radiofrequency (RF) catheter compared with that of the existing RF catheter in a canine model. @*Methods@#Seven dogs underwent ablation using 1 control catheter (ClosureFAST, CF; Covidien) and 1 experimental catheter (VENISTAR, VS; STARmed Co., Ltd.) in the femoral and cephalic veins. The ablated vein was evaluated macroscopically (2,3,5-triphenyltetrazolium chloride staining, TTC), microscopically (hematoxylin and eosin staining), and ultrasonographically. Vessel injury score was used to evaluate the ablating effect objectively. Veins from 1 dog were evaluated on the day of ablation, while in the remaining 6 dogs, the ablated veins were evaluated 2 weeks later. @*Results@#A total of 23 veins (CF, 11 veins; VS, 12 veins) were ablated in 7 dogs. Non–TTC-stained vein wall areas were identified in all ablated veins. No significant difference was observed in the mean vessel injury score (2.54 ± 1.16 vs. 2.42 ± 1.13, P = 0.656) and the mean vessel wall thickness (0.32 ± 0.03 mm vs. 0.31 ± 0.05 mm, P = 0.212) between CF and VS. There was no blood flow in all veins ablated with VS, whereas there was remaining blood flow in 1 vein ablated with CF. Perivenous complication was not observed. @*Conclusion@#Endovenous RF ablation using a newly developed VS RF catheter seems to provide comparable occlusion rate and degree of vein wall injury without perivenous adverse events compared to the most commonly used RF catheter (CF).

Persistent Trigeminal Artery Variant Terminating in the Ipsilateral Superior Cerebellar Artery

Persistent trigeminal artery (PTA) represent an unusual remnant of the fetal carotid-basilar anastomosis. Persistent trigeminal artery variant (PTAV) is a rare anastomosis between the internal carotid artery and cerebellar artery, without an interposing basilar artery segment. We report the case of 49-year-old female with an incidentally discovered, rare variation of PTA that directly terminated in the ipsilateral superior cerebellar artery. The variation was observed on CT angiography, digital subtraction angiography, and MR angiography. Additionally, we reviewed the embryogenesis of PTA and PTAV and discussed the clinical implications of this variation.

The Influence of Pharyngeal Strength on the Outcome of Botulinum Toxin Treatment for Difficulty in Relaxation of the Upper Esophageal Sphincter / 대한연하장애학회지

Objective@#Botulinum toxin was used to treat patients with difficulty in relaxation of the upper esophageal sphincter (UES), but the treatment did not always yield good results. We, therefore, attempted to investigate if there was any other factor affecting the outcome and hypothesized that this could be caused due to pharyngeal constriction. @*Methods@#We conducted a retrospective study on a botulinum toxin injection treatment given to eleven patients with nasal backflow and pharyngeal stasis in the course of a videofluoroscopic swallowing study from August 2006 to December 2012. After the injection, the cases showing an esophageal passage of diluted barium regardless of aspiration were defined as “good”, and the cases showing no passage were defined as “bad”. Pharyngeal strength was measured using the pharyngeal constriction ratio (PCR), which was compared between the two groups using the Mann-Whitney U test for proving the hypothesis. @*Results@#Five of the eleven patients showed esophageal passage after the injection treatment and were assigned to the “good” group. The remaining 6 were assigned to the “bad” group. When comparing the average PCR of each group, the ‘good’ group’s ratio was at 0.09±0.03 and the ‘bad’ group was at 0.29±0.16, showing a statistically significant difference (P＜0.05). @*Conclusion@#The strength of pharyngeal constriction could be considered to be an important factor influencing the outcome after botulinum toxin treatment for the difficulty in relaxation of the UES.

Relationship between Anconeus Epitrochlearis and Ulnar Motor Nerve Conduction Velocity

Objective@#To determine the incidence of anconeus epitrochlearis (AE) muscle and evaluate the correlation between AE muscle and ulnar motor nerve conduction velocity (NCV). Method: Forty healthy volunteers (80 arms) were evaluated. Ulnar motor nerve conduction study was performed. NCVs at the forearm and across the elbow were calculated. Ultrasonography (US) was used to obtain a transverse scan view of the cubital tunnel and confirm the presence of the AE muscle. Cross-sectional areas (CSAs) of following structures were obtained: ulnar nerve (UNCSA), cubital tunnel (CTCSA), and AE (AECSA). AECSA was divided by CTCSA to obtain the AE/CT ratio. Pearson correlation coefficient (PCC) was calculated to evaluate the relationship between NCV across elbow and each variable obtained by US. @*Results@#Sixty-three (78.75%) of eighty arms showed the presence of AE muscle. NCV had no significant correlations with sonographic variables. However, when 17 arms with a relatively low NCV value (≤ 60 m/s) were analyzed, NCV showed significant correlations with AECSA (PCC: r = −0.674, p=0.003) and AE/CT ratio (PCC: r = −0.516, p=0.034). @*Conclusion@#When all 63 cases with AE muscle were analyzed, ulnar NCV showed no significant correlations with sonographic variables. However, when those with NCV value of 60 m/s or less were analyzed, NCV showed significant negative correlations with AECSA and AE/CT ratio.

Analysis of the root position and angulation of maxillary premolars in alveolar bone using cone-beam computed tomography

Purpose@#This study investigated whether the relationship between the maxillary sinus and the root of the maxillary premolar is correlated with the root position and whether there is a difference in the long axis angle of premolars and the buccal bone thickness according to the sinus-root relationship and root position. @*Materials and Methods@#Cone-beam computed tomographic images of 587 maxillary first premolars and 580 second premolars from 303 patients were retrospectively reviewed. The maxillary sinus floor-root relationship was classified into 4 types, and the root position in the alveolar bone was evaluated as buccal, middle, or palatal. The long axis angle of the maxillary premolars in the alveolar bone and the buccal bone thickness were measured. The correlation between these parameters was analyzed. @*Results@#The maxillary sinus floor-root relationship showed a statistically significant correlation with the root position in the alveolar bone. Most maxillary first premolars were buccally located, and more than half of the second premolars had their roots in the middle. The long axis angle of the premolars was significantly larger in buccal-positioned teeth than in middle-positioned teeth, and the buccal bone was thinner. @*Conclusion@#When the root of the maxillary premolar was separated from the sinus floor, the premolar was often located on the buccal side. Most of the maxillary first premolars had a thinner buccal bone and larger inclination than the second premolars. It is recommended to evaluate the root position, sagittal angle and buccal bone thickness using CBCT for implant treatment planning.

Aggressive central odontogenic fibroma in the maxilla: A case report

A central odontogenic fibroma is a rare benign tumor composed of mature fibrous connective tissue with variable amounts of odontogenic epithelium. It appears at similar rates in the maxilla and mandible. In the maxilla, it usually occurs anterior to the molars. Radiographically, central odontogenic fibroma commonly presents as a multilocular or unilocular radiolucency with a distinct border. This paper reports a case of an aggressive central odontogenic fibroma involving the right posterior maxilla of a 53-year-old man. Radiographs showed an extensive soft tissue mass involving the entire right maxilla with frank bone resorption. The patient had a history of 2 operations in the region, both more than 2 decades ago. Although it was impossible to confirm the previous diagnoses, it was presumed that this case was a recurrent lesion.

Hyperuricemia Is Not Predictive of Long-Term Outcome in Patients with Stable Chronic Obstructive Pulmonary Disease

BACKGROUND@#Although the association of hyperuricemia with an increased risk of mortality has been demonstrated in the context of acute exacerbation of chronic obstructive pulmonary disease (COPD), the long-term outcomes of hyperuricemia have not been studied in the case of stable COPD.@*METHODS@#We retrospectively analyzed baseline data of 240 men with stable COPD enrolled in the Korea Obstructive Lung Disease cohort. We evaluated associations between serum uric acid levels and clinical parameters, risk factors for all-cause mortality, and acute exacerbation of COPD.@*RESULTS@#The mean age of subjects was 66.4 ± 7.7 years, and the median follow-up time was 5.9 years. We identified no significant difference in terms of lung function or laboratory findings between patients with hyperuricemia and those without. Serum uric acid level was negatively associated with systemic inflammation indicated by neutrophil–lymphocyte ratio (r = −0.211, P = 0.001). Univariate Cox regression analysis revealed hyperuricemia to not be associated with an increased risk of all-cause mortality in men with stable COPD (hazard ratio [HR], 0.580; 95% confidence interval [CI], 0.250–1.370; P = 0.213). In the multivariate Cox regression model, hyperuricemia was not an independent predictor of acute exacerbation (HR, 1.383; 95% CI, 0.977–1.959; P = 0.068).@*CONCLUSION@#Among men with stable COPD, hyperuricemia is not an independent predictor of all-cause mortality or future acute exacerbation of COPD. These results differ from those of previous studies on patients with acute exacerbation of COPD.

Epidemiology of Antiphospholipid Syndrome in Korea: a Nationwide Population-based Study

BACKGROUND@#Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by arterial and venous thrombosis or pregnancy morbidity in patients with persistent antiphospholipid antibodies. However, nationwide population-based epidemiology studies regarding APS are still unavailable.@*METHODS@#We analyzed claims data extracted from the Korean Health Insurance and Review Agency (HIRA) covering more than 52 million Koreans, between January 1, 2008, and December 31, 2017. Patients diagnosed with APS, as determined by the Korean Classification of Disease, 7th edition (D68.6), and a rare intractable disease program (V253), were identified in HIRA.@*RESULTS@#A total of 3,088 newly diagnosed incident cases of 1,215 men and 1,873 women were identified during 2009–2016. The mean age was 44.6 ± 16.6 (men, 47.4 ± 16.3; women, 42.8 ± 16.6) years. The incidence was 0.75 per 105 person-year (95% confidence interval, 0.73–0.78). The prevalence in 2016 was 6.19 per 105 people. For incident cases, women showed incidence peak at ages of 30–39 years and 70–79 years, whereas for men, it was highest at ages of 70–79 years only. Of all patients, 1,766 (57%, 810 men and 956 women) had primary APS, 1,322 (43%, 405 men and 917 women) had secondary APS, and 845 (27%, 216 men and 629 women) were associated with systemic lupus erythematosus (SLE).@*CONCLUSION@#The incidence of APS differs according to age groups and gender. The incidence of primary APS was higher than that of secondary APS in both gender. Furthermore, as already reported, secondary APS is highly associated with SLE; however, we observed that rheumatoid arthritis is also highly related.

Hyperuricemia Is Not Predictive of Long-Term Outcome in Patients with Stable Chronic Obstructive Pulmonary Disease

BACKGROUND@#Although the association of hyperuricemia with an increased risk of mortality has been demonstrated in the context of acute exacerbation of chronic obstructive pulmonary disease (COPD), the long-term outcomes of hyperuricemia have not been studied in the case of stable COPD.@*METHODS@#We retrospectively analyzed baseline data of 240 men with stable COPD enrolled in the Korea Obstructive Lung Disease cohort. We evaluated associations between serum uric acid levels and clinical parameters, risk factors for all-cause mortality, and acute exacerbation of COPD.@*RESULTS@#The mean age of subjects was 66.4 ± 7.7 years, and the median follow-up time was 5.9 years. We identified no significant difference in terms of lung function or laboratory findings between patients with hyperuricemia and those without. Serum uric acid level was negatively associated with systemic inflammation indicated by neutrophil–lymphocyte ratio (r = −0.211, P = 0.001). Univariate Cox regression analysis revealed hyperuricemia to not be associated with an increased risk of all-cause mortality in men with stable COPD (hazard ratio [HR], 0.580; 95% confidence interval [CI], 0.250–1.370; P = 0.213). In the multivariate Cox regression model, hyperuricemia was not an independent predictor of acute exacerbation (HR, 1.383; 95% CI, 0.977–1.959; P = 0.068).@*CONCLUSION@#Among men with stable COPD, hyperuricemia is not an independent predictor of all-cause mortality or future acute exacerbation of COPD. These results differ from those of previous studies on patients with acute exacerbation of COPD.

Epidemiology of Antiphospholipid Syndrome in Korea: a Nationwide Population-based Study

BACKGROUND@#Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by arterial and venous thrombosis or pregnancy morbidity in patients with persistent antiphospholipid antibodies. However, nationwide population-based epidemiology studies regarding APS are still unavailable.@*METHODS@#We analyzed claims data extracted from the Korean Health Insurance and Review Agency (HIRA) covering more than 52 million Koreans, between January 1, 2008, and December 31, 2017. Patients diagnosed with APS, as determined by the Korean Classification of Disease, 7th edition (D68.6), and a rare intractable disease program (V253), were identified in HIRA.@*RESULTS@#A total of 3,088 newly diagnosed incident cases of 1,215 men and 1,873 women were identified during 2009–2016. The mean age was 44.6 ± 16.6 (men, 47.4 ± 16.3; women, 42.8 ± 16.6) years. The incidence was 0.75 per 105 person-year (95% confidence interval, 0.73–0.78). The prevalence in 2016 was 6.19 per 105 people. For incident cases, women showed incidence peak at ages of 30–39 years and 70–79 years, whereas for men, it was highest at ages of 70–79 years only. Of all patients, 1,766 (57%, 810 men and 956 women) had primary APS, 1,322 (43%, 405 men and 917 women) had secondary APS, and 845 (27%, 216 men and 629 women) were associated with systemic lupus erythematosus (SLE).@*CONCLUSION@#The incidence of APS differs according to age groups and gender. The incidence of primary APS was higher than that of secondary APS in both gender. Furthermore, as already reported, secondary APS is highly associated with SLE; however, we observed that rheumatoid arthritis is also highly related.

Ameloblastic carcinoma of the mandible: A case report

Ameloblastic carcinoma is a rare odontogenic malignant tumor with the histologic features of both ameloblastoma and carcinoma. It occurs more frequently in the mandible than in the maxilla and it may appear de novo or develop from a preexisting ameloblastoma or odontogenic cyst. Rapidly progressing, painful swelling is the most common symptom, and radiographically, it shows significant bone resorption and cortical perforation. This report described a case of ameloblastic carcinoma in a 45-year-old man who presented with swelling in the left mandible. The lesion showed combined features of benign findings, such as an expansile cortex with a distinct border, and malignant findings, such as a large exophytic mass with frank bone resorption. Excisional biopsy was performed and a final diagnosis of ameloblastic carcinoma was made.

Comparison of panoramic radiography and cone-beam computed tomography for assessing radiographic signs indicating root protrusion into the maxillary sinus

Purpose@#This study investigated correlations between findings on panoramic radiographs and cone-beam computed tomography (CBCT) to assess the relationship between the maxillary sinus floor and the roots of maxillary posterior teeth. In addition, radiographic signs indicating actual root protrusion into the maxillary sinus were evaluated on panoramic radiographs. @*Materials and Methods@#Paired panoramic radiographs and CBCT images from 305 subjects were analyzed. This analysis classified 2,440 maxillary premolars and molars according to their relationship with the maxillary sinus floor on panoramic radiographs and CBCT images. In addition, interruption of the sinus floor was examined on panoramic radiographs. @*Results@#Root protrusion into the maxillary sinus occurred most frequently in the mesiobuccal roots of the second molars. The classification according to panoramic radiographs and CBCT images was the same in more than 90% of cases when there was no contact between the root apex and the sinus floor. When the panoramic radiograph showed root protrusion into the sinus, the CBCT images showed the same classification in 67.5% of second molars, 48.8% of first molars, and 53.3% of second premolars. There was a statistically significant relationship between interruption of the sinus floor on panoramic radiographs and root protrusion into the sinus on CBCT images. @*Conclusion@#The presence of root protrusion into the sinus on panoramic radiographs demonstrated a moderate ability to predict root protrusion into the maxillary sinus. Interruption of the maxillary sinus floor could be considered an indicator of actual root protrusion into the maxillary sinus.

Very deep super-resolution for efficient cone-beam computed tomographic image restoration

Purpose@#As cone-beam computed tomography (CBCT) has become the most widely used 3-dimensional (3D) imaging modality in the dental field, storage space and costs for large-capacity data have become an important issue. Therefore, if 3D data can be stored at a clinically acceptable compression rate, the burden in terms of storage space and cost can be reduced and data can be managed more efficiently. In this study, a deep learning network for super-resolution was tested to restore compressed virtual CBCT images. @*Materials and Methods@#Virtual CBCT image data were created with a publicly available online dataset (CQ500) of multidetector computed tomography images using CBCT reconstruction software (TIGRE). A very deep superresolution (VDSR) network was trained to restore high-resolution virtual CBCT images from the low-resolution virtual CBCT images. @*Results@#The images reconstructed by VDSR showed better image quality than bicubic interpolation in restored images at various scale ratios. The highest scale ratio with clinically acceptable reconstruction accuracy using VDSR was 2.1. @*Conclusion@#VDSR showed promising restoration accuracy in this study. In the future, it will be necessary to experiment with new deep learning algorithms and large-scale data for clinical application of this technology.

Hyperuricemia Is Not Predictive of Long-Term Outcome in Patients with Stable Chronic Obstructive Pulmonary Disease

BACKGROUND: Although the association of hyperuricemia with an increased risk of mortality has been demonstrated in the context of acute exacerbation of chronic obstructive pulmonary disease (COPD), the long-term outcomes of hyperuricemia have not been studied in the case of stable COPD.METHODS: We retrospectively analyzed baseline data of 240 men with stable COPD enrolled in the Korea Obstructive Lung Disease cohort. We evaluated associations between serum uric acid levels and clinical parameters, risk factors for all-cause mortality, and acute exacerbation of COPD.RESULTS: The mean age of subjects was 66.4 ± 7.7 years, and the median follow-up time was 5.9 years. We identified no significant difference in terms of lung function or laboratory findings between patients with hyperuricemia and those without. Serum uric acid level was negatively associated with systemic inflammation indicated by neutrophil–lymphocyte ratio (r = −0.211, P = 0.001). Univariate Cox regression analysis revealed hyperuricemia to not be associated with an increased risk of all-cause mortality in men with stable COPD (hazard ratio [HR], 0.580; 95% confidence interval [CI], 0.250–1.370; P = 0.213). In the multivariate Cox regression model, hyperuricemia was not an independent predictor of acute exacerbation (HR, 1.383; 95% CI, 0.977–1.959; P = 0.068).CONCLUSION: Among men with stable COPD, hyperuricemia is not an independent predictor of all-cause mortality or future acute exacerbation of COPD. These results differ from those of previous studies on patients with acute exacerbation of COPD.

Combination Therapy With Polydeoxyribonucleotide and Pirfenidone Alleviates Symptoms of Acute Respiratory Distress Syndrome in Human Lung Epithelial A549 Cells / 대한배뇨장애요실금학회지

Purpose@#Acute respiratory distress syndrome (ARDS) is characterized by its acute onset of symptoms such as bilateral pulmonary infiltrates, severe hypoxemia, and pulmonary edema. Many patients with ARDS survive in the acute phase, but then die from significant lung fibrosis. @*Methods@#The effect of combination therapy with polydeoxyribonucleotide (PDRN) and pirfenidone on ARDS was investigated using human lung epithelial A549 cells. ARDS environment was induced by treatment with lipopolysaccharide and transforming growth factor (TGF)-β. Enzyme-linked immunoassay for connective tissue growth factor (CTGF) and hydroxyproline were conducted. Western blot for collagen type I, fibroblast growth factor (FGF), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 was performed. @*Results@#In this study, 8-μg/mL PDRN enhanced cell viability. Combination therapy with PDRN and pirfenidone and pirfenidone monotherapy suppressed expressions of CTGF and hydroxyproline and inhibited expressions of collagen type I and FGF. Combination therapy with PDRN and pirfenidone and PDRN monotherapy suppressed expression of TNF-α and IL-1β. @*Conclusions@#The combination therapy with PDRN and pirfenidone exerted stronger therapeutic effect against lipopolysaccharide and TGF-β-induced ARDS environment compared to the PDRN monotherapy or pirfenidone monotherapy. The excellent therapeutic effect of combination therapy with PDRN and pirfenidone on ARDS was shown by promoting the rapid anti-inflammatory effect and inhibiting the fibrotic processes.

Epidemiology of Antiphospholipid Syndrome in Korea: a Nationwide Population-based Study

High-Altitude Cerebral Edema Evaluated with MRI: A Case Report

High-altitude cerebral edema (HACE) is a rare life-threatening condition observed in individuals who climb high altitudes. This report describes the case of a 38-year-old man who recently climbed a 5000-m-high mountain, showing the following radiologic findings at 3 different anatomical locations: 1) increased T2 signal intensity (SI) without restricted diffusion, with full recovery in the posterior limb of the left internal capsule; 2) increased T2 SI with restricted diffusion, with full recovery in the splenium of the corpus callosum; and 3) increased T2 SI with restricted diffusion and microbleeds, resulting in bilateral encephalomalacia in the globus pallidus. Herein, we report the concurrent typical and atypical radiologic findings of this rare condition caused by vasogenic and cytotoxic edema.

An overview of deep learning in the field of dentistry

PURPOSE: Artificial intelligence (AI), represented by deep learning, can be used for real-life problems and is applied across all sectors of society including medical and dental field. The purpose of this study is to review articles about deep learning that were applied to the field of oral and maxillofacial radiology. MATERIALS AND METHODS: A systematic review was performed using Pubmed, Scopus, and IEEE explore databases to identify articles using deep learning in English literature. The variables from 25 articles included network architecture, number of training data, evaluation result, pros and cons, study object and imaging modality. RESULTS: Convolutional Neural network (CNN) was used as a main network component. The number of published paper and training datasets tended to increase, dealing with various field of dentistry. CONCLUSION: Dental public datasets need to be constructed and data standardization is necessary for clinical application of deep learning in dental field.

Maxillary antroliths detected by cone-beam computed tomography in an adult dental population

PURPOSE: This study evaluated the prevalence and characteristics of maxillary antroliths using cone-beam computed tomography (CBCT) scans performed for maxillofacial diagnostic purposes. MATERIALS AND METHODS: CBCT scans of 13,946 patients over the age of 20 were reviewed for maxillary antroliths, and prevalence according to sex, age, and the side of the jaw was calculated. The relationships of single or multiple antroliths with sex, side, and the degree of sinus inflammation were evaluated. The shape and dimension of antroliths were also assessed. The data were analyzed using descriptive statistics, the chi-square or Fisher exact tests, and Kendall's tau-b. RESULTS: A total of 138 (0.99%) of the 13,946 patients showed an antrolith in at least 1 sinus. Only 18 patients presented a bilateral manifestation, which brought the total number of sinuses containing an antrolith to 156 (0.56%). Multiple antroliths were observed in 36 sinuses, and the total number of antroliths was 207: 110 punctate, 65 linear, and 32 amorphous. The antrolith dimensions varied from 1 mm2 to 91 mm2 (average, 10.2±15.5 mm2). No statistically significant differences were found according to sex, side, and age group (P>0.05). However, there was a statistically significant difference between the multiplicity of antrolith and the degree of sinus inflammation (P<0.05). CONCLUSION: Cone-beam computed tomography is an effective modality for the detection of incidental antroliths. Maxillary antroliths were found to be very rare and were usually asymptomatic. Dentists should have a comprehensive understanding of their diagnosis and treatment in light of possible associated dental problems.

Current Status of Noninvasive Ventilation Use in Korean Intensive Care Units: A Prospective Multicenter Observational Study / 결핵

BACKGROUND: Data on noninvasive ventilation (NIV) use in intensive care units (ICUs) are very limited in South Korea. METHODS: A prospective observational study was performed in 20 ICUs of university-affiliated hospitals from June 2017 to February 2018. Adult patients (age>18 years) who were admitted to the ICU and received NIV treatment for acute respiratory failure were included. RESULTS: A total of 156 patients treated with NIV were enrolled (mean age, 71.9±11.6 years). The most common indications for NIV were acute hypercapnic respiratory failure (AHRF, n=89) and post-extubation respiratory failure (n=44). The main device for NIV was an invasive mechanical ventilator with an NIV module (61.5%), and the majority of patients (87.2%) used an oronasal mask. After the exclusion of 32 do-not-resuscitate patients, NIV success rate was 68.5% (85/124); ICU and hospital mortality rates were 8.9% and 15.3%, respectively. However, the success rate was lower in patients with de novo respiratory failure (27.3%) compared to that of patients with AHRF (72.8%) or post-extubation respiratory failure (75.0%). In multivariate analysis, immunocompromised state, de novo respiratory failure, post-NIV (2 hours) respiratory rate, NIV mode (i.e., non-pressure support ventilation mode), and the change of NIV device were significantly associated with a lower success rate of NIV. CONCLUSION: AHRF and post-extubation respiratory failure were the most common indications for NIV in Korean ICUs. Overall NIV success was achieved in 68.5% of patients, with the lowest rate in patients with de novo respiratory failure.