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Featured researches published by Hyun Ho Ryu.


Prehospital Emergency Care | 2012

Comparison of Emergency Medical Services Systems Across Pan-Asian Countries: A Web-based Survey

Sang Do Shin; Marcus Eng Hock Ong; Hideharu Tanaka; Matthew Huei-Ming Ma; Tatsuya Nishiuchi; Omer Alsakaf; Sarah Abdul Karim; Nalinas Khunkhlai; Chih-Hao Lin; Kyoung Jun Song; Hyun Wook Ryoo; Hyun Ho Ryu; Lai Peng Tham; David C. Cone

Abstract Background. There are great variations in out-of-hospital cardiac arrest (OHCA) survival outcomes among different countries and different emergency medical services (EMS) systems. The impact of different systems and their contribution to enhanced survival are poorly understood. This paper compares the EMS systems of several Asian sites making up the Pan-Asian Resuscitation Outcomes Study (PAROS) network. Some preliminary cardiac arrest outcomes are also reported. Methods. This is a cross-sectional descriptive survey study addressing population demographics, service levels, provider characteristics, system operations, budget and finance, medical direction (leadership), and oversight. Results. Most of the systems are single-tiered. Fire-based EMS systems are predominant. Bangkok and Kuala Lumpur have hospital-based systems. Service level is relatively low, from basic to intermediate in most of the communities. Korea, Japan, Singapore, and Bangkok have intermediate emergency medical technician (EMT) service levels, while Taiwan and Dubai have paramedic service levels. Medical direction and oversight have not been systemically established, except in some communities. Systems are mostly dependent on public funding. We found variations in available resources in terms of ambulances and providers. The number of ambulances is 0.3 to 3.2 per 100,000 population, and most ambulances are basic life support (BLS) vehicles. The number of human resources ranges from 4.0 per 100,000 population in Singapore to 55.7 per 100,000 population in Taipei. Average response times vary between 5.1 minutes (Tainan) and 22.5 minutes (Kuala Lumpur). Conclusion. We found substantial variation in 11 communities across the PAROS EMS systems. This study will provide the foundation for understanding subsequent studies arising from the PAROS effort.


Clinical Toxicology | 2010

Caustic injury: can CT grading system enable prediction of esophageal stricture?

Hyun Ho Ryu; Kyung Woon Jeung; Byung Kook Lee; Jun Hwan Uhm; Young Hun Park; Min Ho Shin; Hyun Lee Kim; Tag Heo; Yong Il Min

Background. The aim of this study was to test the utility of our computed tomography (CT) grading system, compared with endoscopy, for association with the development of esophageal stricture in patients with caustic ingestion. Methods. This retrospective case series involved 49 patients with caustic ingestion from 1998 to 2009. The degree of esophageal damage was graded using a scoring system based on the extent of esophageal wall edema and the damage in adjacent tissue as seen on thoracoabdominal CT scans. The presence of esophageal stricture was established by esophagography. Diagnostic performance was compared using receiver operating characteristic (ROC) analysis. Sensitivity and specificity were calculated for the grading system. Results. The CT grading score results showed that grade III was the most common injury (20 cases, 40.8%), followed by grade IV (14 cases, 28.6%), grade II (9 cases, 18.4%), and grade I (6 cases, 12.2%). In addition, damage to the esophagus was significantly correlated with esophageal stricture when the extent of damage approached grades III and IV (p < 0.001). The CT grading system for esophageal stricture resulted in a slightly larger area under the receiver operating characteristic curve (0.90) compared with endoscopic grading system (0.79). The sensitivity and specificity of CT grading system were moderately higher than those of endoscopic grading system. Conclusion. Assessment of the degree of esophageal damage using CT, a noninvasive modality, in patients who visit the emergency department following caustic ingestion should be useful in estimating the occurrence of complications including esophageal stricture.


Resuscitation | 2015

Tilting for perfusion: Head-up position during cardiopulmonary resuscitation improves brain flow in a porcine model of cardiac arrest

Guillaume Debaty; Sang Do Shin; Anja Metzger; Taeyun Kim; Hyun Ho Ryu; Jennifer Rees; Scott McKnite; Timothy Matsuura; Michael Lick; Demetris Yannopoulos; Keith G. Lurie

INTRODUCTION Cerebral perfusion is compromised during cardiopulmonary resuscitation (CPR). We hypothesized that beneficial effects of gravity on the venous circulation during CPR performed in the head-up tilt (HUT) position would improve cerebral perfusion compared with supine or head-down tilt (HDT). METHODS Twenty-two pigs were sedated, intubated, anesthetized, paralyzed and placed on a tilt table. After 6min of untreated ventricular fibrillation (VF) CPR was performed on 14 pigs for 3min with an automated CPR device called LUCAS (L) plus an impedance threshold device (ITD), followed by 5min of L-CPR+ITD at 0° supine, 5min at 30° HUT, and then 5min at 30° HDT. Microspheres were used to measure organ blood flow in 8 pigs. L-CPR+ITD was performed on 8 additional pigs at 0°, 20°, 30°, 40°, and 50° HUT. RESULTS Coronary perfusion pressure was 19±2mmHg at 0° vs. 30±3 at 30° HUT (p<0.001) and 10±3 at 30° HDT (p<0.001). Cerebral perfusion pressure was 19±3 at 0° vs. 35±3 at 30° HUT (p<0.001) and 4±4 at 30° HDT (p<0.001). Brain-blood flow was 0.19±0.04mlmin(-1)g(-1) at 0° vs. 0.27±0.04 at 30° HUT (p=0.01) and 0.14±0.06 at 30° HDT (p=0.16). Heart blood flow was not significantly different between interventions. With 0, 10, 20, 30, 40 and 50° HUT, ICP values were 21±2, 16±2, 10±2, 5±2, 0±2, -5±2 respectively, (p<0.001), CerPP increased linearly (p=0.001), and CPP remained constant. CONCLUSION During CPR, HDT decreased brain flow whereas HUT significantly lowered ICP and improved cerebral perfusion. Further studies are warranted to explore this new resuscitation concept.


Resuscitation | 2011

Variable effects of high-dose adrenaline relative to standard-dose adrenaline on resuscitation outcomes according to cardiac arrest duration.

Kyung Woon Jeung; Hyun Ho Ryu; Kyung Hwan Song; Byung Kook Lee; Hyoung Youn Lee; Tag Heo; Yong Il Min

AIM OF THE STUDY Adjustment of adrenaline (epinephrine) dosage according to cardiac arrest (CA) duration, rather than administering the same dose, may theoretically improve resuscitation outcomes. We evaluated variable effects of high-dose adrenaline (HDA) relative to standard-dose adrenaline (SDA) on resuscitation outcomes according to CA duration. METHODS Twenty-eight male domestic pigs were randomised to the following 4 groups according to the dosage of adrenaline (SDA 0.02 mg/kg vs. HDA 0.2mg/kg) and duration of CA before beginning cardiopulmonary resuscitation (CPR): 6 min SDA, 6 min HDA, 13 min SDA, or 13 min HDA. After the predetermined duration of untreated ventricular fibrillation, CPR was provided. RESULTS All animals in the 6 min SDA, 6 min HDA, and 13 min HDA groups were successfully resuscitated, while only 4 of 7 pigs in the 13 min SDA group were successfully resuscitated (p=0.043). HDA groups showed higher right atrial pressure, more frequent ventricular ectopic beats, higher blood glucose, higher troponin-I, and more severe metabolic acidosis than SDA groups. Animals of 13 min groups showed more severe metabolic acidosis and higher troponin-I than animals of 6 min groups. All successfully resuscitated animals, except two animals in the 13 min HDA group, survived for 7 days (p=0.121). Neurologic deficit score was not affected by the dose of adrenaline. CONCLUSION HDA showed benefit in achieving restoration of spontaneous circulation in 13 min CA, when compared with 6 min CA. However, this benefit did not translate into improved long-term survival or neurologic outcome.


Journal of Korean Medical Science | 2009

The Protective Effects of Green Tea Extract against L-arginine Toxicity to Cultured Human Mesangial Cells

Byung Chul Shin; Hyun Ho Ryu; Jong Hoon Chung; Byoung Rai Lee; Hyun Lee Kim

The aim of this study was to investigate whether green tea extract (GTE) has the protective effects on excess L-arginine induced toxicity in human mesangial cell. Human mesangial cells treated with L-arginine were cultured on Dulbeccos modified eagle medium in the presence and absence of inducible nitric oxide synthase (iNOS) inhibitor and GTE. The cell proliferation was determined by 3 (4,5-dimethylthiazol-2-yl)-2, 5-diphengltetrqzolium bromide, a tetrazole assay. The iNOS mRNA and its protein expression were detected by reverse transcription polymerase chain reaction and Western blot, respectively. The concentration of nitric oxide (NO) was measured by NO enzyme-linced immuno sorbent assay kit. L-arginine significantly inhibited the proliferation of human mesangial cells, and induced the secretion of NO to the media. NO production by L-arginine was significantly suppressed by GTE and iNOS inhibitor (p<0.01). The expression level of iNOS mRNA and its protein that was significantly increased by L-arginine was decreased by iNOS inhibitor but not by GTE. GTE protected the mesangial cells from the NO-mediated cytotoxicity by scavenging the NO rather than by iNOS gene expression. Therefore, we conclude that GTE has some protective effect for renal cells against oxidative injury possibly by polyphenols contained in GTE.


Nephrology Dialysis Transplantation | 2011

Renoprotective effects of green tea extract on renin-angiotensin-aldosterone system in chronic cyclosporine-treated rats

Hyun Ho Ryu; Hyun Lee Kim; Jong Hoon Chung; Byoung Rai Lee; Tae Hyoung Kim; Byung Chul Shin

BACKGROUND Renin-angiotensin-aldosterone system (RAAS) activation plays an important role in cyclosporine (CsA)-induced nephropathy. The main aim of this study was to test whether the administration of green tea extract (GTE) prevents the development of CsA-induced nephrotoxicity. METHODS The rats were treated for 21 days and divided into four groups (n = 6/group): control group (0.9% saline injection), CsA group (30 mg/kg/day by intraperitoneal injection), CsA-GTE group (CsA plus GTE 100 mg/kg/day subcutaneous injection) and GTE group (GTE alone). RESULTS There were significant increased levels of serum blood urea nitrogen and creatinine in the CsA group compared with that of the control group and significantly improved in the CsA-GTE group. Biochemical analysis showed that the plasma renin activity (PRA) and serum concentration of aldosterone were significantly increased in the CsA group compared with the control group and significantly decreased in the CsA-GTE group compared with the CsA group. The total level of renin protein expression was significantly higher in the CsA group than in the control group, and it was lower in the CsA-GTE group than in the CsA group. CONCLUSIONS CsA treatment increases the PRA and intrarenal renin levels and induces nephrotoxicity. The protective effects of GTE on CsA-induced structural and functional alternations of the kidney may be the blockage of RAAS.


Journal of Emergency Medicine | 2012

A case of pylephlebitis secondary to cecal diverticulitis.

Byung Kook Lee; Hyun Ho Ryu

BACKGROUND Pylephlebitis, which has high rates of morbidity and mortality, is thrombosis in the hepatic and portal veins. Hypercoagulability and intra-abdominal sepsis can lead to pylephlebitis, which can progress to liver abscess, mesenteric ischemia, and infarction. CASE REPORT A 47-year-old man presented to the Emergency Department complaining of fever, epigastric pain, and jaundice. He was diagnosed with pylephlebitis secondary to diverticulitis, as well as having a diverticular abscess, and was treated with antibiotic therapy without surgery or anticoagulation. CONCLUSION Early diagnosis is essential for the treatment of pylephlebitis. Antibiotics and anticoagulants are the mainstay of treatment for pylephlebitis; although the use of anticoagulants remains controversial. In the present case, pylephlebitis was treated successfully without anticoagulants.


Prehospital Emergency Care | 2013

Recommendations on Ambulance Cardiopulmonary Resuscitation in Basic Life Support Systems

Marcus Eng Hock Ong; Sang Do Shin; Soon Swee Sung; Hideharu Tanaka; Matthew Huei-ming; Kyoung Jun Song; Tatsuya Nishiuchi; Benjamin Sieu Hon Leong; Sarah Abdul Karim; Chih-Hao Lin; Hyun Wook Ryoo; Hyun Ho Ryu; Taku Iwami; Kentaro Kajino; Patrick Chow-In Ko; Kyung Won Lee; Nathida Sumetchotimaytha; Robert A. Swor; Brent Myers; Kevin E. Mackey; Bryan McNally

AbstractAim. Cardiopulmonary resuscitation (CPR) during ambulance transport can be a safety risk for providers and can affect CPR quality. In many Asian countries with basic life support (BLS) systems, patients experiencing out-of-hospital cardiac arrest (OHCA) are routinely transported in ambulances in which CPR is performed. This paper aims to make recommendations on best practices for CPR during ambulance transport in BLS systems. Methods. A panel consisting of 20 experts (including 4 North Americans) in emergency medical services (EMS) and resuscitation science was selected, and met over two days. We performed a literature review and selected 33 candidate issues in five core areas. Using Delphi methodology, the issues were classified into dichotomous (yes/no), multiple choice, and ranking questions. Primary consensus between experts was reached when there was more than 70% agreement. Questions with 60–69% agreement were made more specific and were submitted for a second round of voting. Results. The panel agreed upon 24 consensus statements with more than 70% agreement (2 rounds of voting). The recommendations cover the following: length of time on the scene; advanced airway at the scene; CPR prior to transport; rhythm analysis and defibrillation during transport; prehospital interventions; field termination of resuscitation (TOR); consent for TOR; destination hospital; transport protocol; number of staff members; restraint systems; mechanical CPR; turning off of the engine for rhythm analysis; alternative CPR; and feedback for CPR quality. Conclusion. Recommendations for CPR during ambulance transport were developed using the Delphi method. These recommendations should be validated in clinical settings.


Emergency Medicine Australasia | 2010

Bowel perforations induced by multiple magnet ingestion.

Byung Kook Lee; Hyun Ho Ryu; Jeong Mi Moon; Kyung Woon Jeung

We report two cases of bowel perforation that presented to the ED after ingesting multiple magnets as diagnosed with exploratory laparotomy. Foreign body ingestion is a common occurrence in the paediatric population. Diagnosis is often delayed because it is difficult to obtain a precise history of foreign body ingestion. Fortunately, in many cases, ingested foreign bodies pass spontaneously without complications. However, surgical intervention is required for about one percent of foreign body ingestions. Multiple magnet ingestion produces bowel injuries, including bowel obstruction, ischaemia, necrosis, perforation and fistula formation, finally requiring surgical intervention. The incidence, which is rare, of magnet ingestion with complications has increased as a result of the popularity of magnetic toys. This case report highlights the complications that might occur with multiple magnet ingestion. We aim to alert physicians that multiple magnet ingestion can be a serious matter.


Resuscitation | 2016

The Effect of Head Up Cardiopulmonary Resuscitation on Cerebral and Systemic Hemodynamics.

Hyun Ho Ryu; Johanna C. Moore; Demetris Yannopoulos; Michael Lick; Scott McKnite; Sang Do Shin; Tae Yun Kim; Anja Metzger; Jennifer Rees; Adamantios Tsangaris; Guillaume Debaty; Keith G. Lurie

AIM Chest compressions during cardiopulmonary resuscitation (CPR) increase arterial and venous pressures, delivering simultaneous bidirectional high-pressure compression waves to the brain. We hypothesized that this may be detrimental and could be partially overcome by elevation of the head during CPR. MEASUREMENTS Female Yorkshire farm pigs (n=30) were sedated, intubated, anesthetized, and placed on a table able to elevate the head 30° (15cm) (HUP) and the heart 10° (4cm) or remain in the supine (SUP) flat position during CPR. After 8minutes of untreated ventricular fibrillation and 2minutes of SUP CPR, pigs were randomized to HUP or SUP CPR for 20 more minutes. In Group A, pigs were randomized after 2minutes of flat automated conventional (C) CPR to HUP (n=7) or SUP (n=7) C-CPR. In Group B, pigs were randomized after 2minutes of automated active compression decompression (ACD) CPR plus an impedance threshold device (ITD) SUP CPR to either HUP (n=8) or SUP (n=8). RESULTS The primary outcome of the study was difference in CerPP (mmHg) between the HUP and SUP positions within groups. After 22minutes of CPR, CerPP was 6±3mmHg in the HUP versus -5±3 in the SUP (p=0.016) in Group A, and 51±8 versus 20±5 (p=0.006) in Group B. Coronary perfusion pressures after 22minutes were HUP 6±2 vs SUP 3±2 (p=0.283) in Group A and HUP 32±5 vs SUP 19±5, (p=0.074) in Group B. In Group B, 6/8 pigs were resuscitated in both positions. No pigs were resuscitated in Group A. CONCLUSIONS The HUP position in both C-CPR and ACD+ITD CPR significantly improved CerPP. This simple maneuver has the potential to improve neurological outcomes after cardiac arrest.

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Byung Kook Lee

Chonnam National University

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Kyung Woon Jeung

Chonnam National University

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Sang Do Shin

Seoul Metropolitan Government

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Tag Heo

Chonnam National University

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Yong Il Min

Chonnam National University

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Hyoung Youn Lee

Chonnam National University

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Kyoung Jun Song

Seoul National University Hospital

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Hyun Wook Ryoo

Kyungpook National University

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Jeong Mi Moon

Chonnam National University

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