Analysis on Behavior of Structural Details for Open Ribs Orthotropic Steel Deck according to Load Pattrens

강바닥판 교량은 비교적 얇은 강판을 사용하여 종&#8231횡리브 및 가로보 등이 용접에 의해 조립되는 구조이므로 연결부 등 여러 구조상세에서의 응력 상태가 매우 복잡하며, 용접에 의한 결함과 변형 등이 발생할 가능성이 매우 높다. 실제 강바닥판 교량에서 피로균열은 주부재가 아닌 2차부재의 용접연결부에서 발생하고 있다. 그러나 교량의 설계 시에는 주부재를 대상으로 한 응력 검토만 이루어지고 있으며, 피로균열이 발생하는 구조상세에 대한 상세 응력 검토 및 거동 특성 분석은 이루어지지 않고 있다. 따라서 본 연구에서는 공용년수 29년된 강바닥판 교량을 대상으로 피로균열이 발생한 원인을 조사하고, 재하시험 및 실교통류 흐름하에서의 계측을 통하여 대상 구조상세의 거동 특성을 분석하였다. 또한 공용중 응력빈도계측을 통해 잔존 피로수명을 예측하고, 기존 교량의 피로안전성을 검토하였다. 피로균열 발생이 보고되고 있는 세로리브 및 다이아프램 용접부를 대상으로 격자해석 및 상세해석을 실시하고, 강바닥판에 대한 상세 영향면해석을 이용하여 하중 이동에 따른 강바닥판의 거동 특성을 조사하였다. 이를 통하여 대상교량의 피로균열 발생 원인을 규명하고자 하였다. 연구 결과, 주거더의 응력파형은 전체 하중의 영향을 받아 장주기의 파형을 나타내나 대상 구조상세의 응력파형은 차축의 영향을 크게 받아 단주기의 응력파형을 나타내는 것으로 나타났다. 공용중 응력빈도계측을 통한 피로안전성 검토 결과, 피로균열이 발생한 구조상세는 거의 잔존피로수명이 없는 것으로 나타났으며, 조속한 유지·보수 방안이 강구되어야 할 것으로 판단된다. 그리고 구조해석 결과, 대상 구조상세에서의 최대응력 발생 위치는 주거더의 최대응력 발생 위치와 거의 일치하나 최소응력 발생 위치는 국부거동을 나타내는 대상 구조상세의 영향선해석에 기초하여 평가하는 것이 바람직하다고 판단된다. 또한 국부거동의 영향을 받는 구조상세에 대한 최대응력 및 최소응력의 변화는 재하차량의 대수에 크게 영향을 받지 않으므로 피로평가는 1대의 재하트럭을 사용하는 것이 효율적일 것이라 판단된다. 세로리브 용접부 등과 같은 구조상세에서 차량 진동 등으로 인하여 면외응력이 발생하였으며, 이러한 면외응력은 피로손상의 원인이라 판단된다.1장. 서 론 1 1.1 연구의 배경과 목적 1 1.2 연구 동향 3 1.3 연구의 범위 및 방법 5 2장. 강바닥판의 피로균열 및 피로수명 6 2.1 강바닥판의 피로균열 6 2.2 피로수명 평가 9 2.2.1 피로수명 평가 개요 9 2.2.2 응력빈도해석 10 2.2.3 잔존수명 평가 11 3장. 대상교량의 제원 및 계측데이터 분석 16 3.1 대상교량 제원 및 특성 16 3.2 피로균열 현황 18 3.3 현장계측 개요 23 3.3.1 재하하중에 의한 계측 23 3.3.2 실교통류 흐름하에서의 계측 25 3.4 실교통류 흐름하의 계측 분석 26 3.4.1 변위 계측 결과 분석 26 3.4.2 변형률 계측 결과 분석 29 3.5 피로수명 및 잔존수명 평가결과 33 4장. 구조해석을 통한 거동 특성 분석 36 4.1 재하하중에 의한 구조해석 36 4.1.1 구조해석 모델 검증 36 4.1.2 재하하중에 의한 상세 해석 39 4.1.3 재하하중에 의한 구조해석 결과 40 4.2 실교통 하중에 의한 구조해석 45 4.2.1 구조해석 모델 검증 45 4.2.2 구조해석을 통한 거동 특성 분석 48 5장. 결 론 62 5.1 결론 62 5.2 향후 과제 63 참고문헌 6

Submental Intubation in Panfacial Trauma Patient: A Case Report

The technique of submental intubation in patient with multiple facial fracture and skull base fracture was originally described by Altemir. Not only is intermaxillary fixation feasible when using this surgical technique but a good field of vision is acquirable, and postoperative complications due to tracheostomy can be prevented. After Altemir presented submental intubation, many modified techniques were reported, applicable not only to trauma patients but also to elective surgeries such as orthognathic surgery including Lefort II or III osteotomy. This technique is easy to use, rapid and free of complications compared to alternative intubation method especially tracheostomy for multiple facial trauma patients.ope

Motor Weakness on Lower Extremities after the Combined Spinal-epidural Anesthesia and Analgesia

The spinal-epidural nerve block is widely used for anesthesia or postoperative pain control. The incidence of neurological complications after spinal and epidural anesthesia is increased although it is usually transient. Such complications may be caused by various mechanical, chemical, and ischemic factors. We experienced a case of motor weakness following combined spinal-epidural anesthesia and analgesia. The motor weakness and hypoesthesia were reversible on right leg, but persistent on left leg.ope

Effects of Acute Normovolemic Hemodilution under Induced Hypotension on Blood Saving and Homologous Transfusion in Orthognathic Two Jaw Surgery

Backgroungd: To avoid complications of homologous transfusion, many methods are being used in patients who undergo an operation, and autologous transfusion is the most popular modality. Acute normovolimic hemodilution (ANH) is recognized as the easiest, the most economical and valuable autologous blood saving method among the types of autotransfusion. This study was performed to investigate the clinical usefulness of ANH under inducd hypotensive anesthesia to reduce blood loss and homologous transfusion in orthognathic two jaw operation. Methods: Thirty patients were randomized divided into two groups; with ANH (n = 15) and without ANH (n = 15). The surgery was limited to one surgeon, with genioplasty, and no bone graft. All patients were pre-donated 2 units of autologous blood before operation. All the surgery was done under induced hypotension by nitroglycerine and esmolol, target mean arterial pressure was aimed at 70% of preoperative blood pressure. In with ANH group, autologous blood were procured immediately after anesthetic induction while 6% hydroxyethyl starch solution were infused to maintain normovolemia until lowering hematocrit to 28%. Results: The two groups did neither differ significantly with demographic data and preoperative evaluation finding. Nor in operation time, surgeon´s satisfiaction to surgical field, serial central venous pressure, hematocrit´s value, prothrombin time, activated partial thromboplastin time. All patients needed transfusion of pre-dunated 2 units of autologous blood during operation, but there was significantly reduced demand for homologous packed RBC transfusion in the with ANH group compared with the control group (0.0 ± 0.0 unit vs. 1.7 ± 1.2 unit, P = 0). Blood saving effects was so greater in with ANH group (total blood loss; 1110.0 ± 154.9 ㏄ vs. 833.3 ± 156.6 ㏄, P = 0). In addition, the amount of agents for induced hypotension was smaller in with ANH group (nitroglycerine: 11.3 ± 2.4 ㎎ vs. 9.9 ± 2.4 ㎎, P = 0.012, esmolol: 52.0 ± 28.2 ㎎ vs. 14.6 ± 8.3 ㎜, P = 0). Conclusions: ANH with pre-donated antologous blood under induced hypotension can reduce intraoperative blood loss and homologous transfusion requirements in othhognathic two jaw operation.ope

Efficacy of Remifentanil-induced Controlled Hypotension for Orthognathic Two Jaw Surgery

Background : Controlled hypotension is used to reduce bleeding and improve surgical conditions during surgery. Remifentanil is an ultrashort-acting opioid with potent analgesic effect and is useful for rapid emergence. This study was performed to investigate the clinical usefulness of remifentanil for induced hypotension during orthognathic surgery. Methods : Fifty adult patients scheduled for orthognathic two jaw surgery were randomly allocated to nitroglycerin (group N) and remifentanil group (group R). After induction of anesthesia, group N (n = 25) was infused with nitroglycerin to induce hypotension, and group R (n = 25) was infused with remifentanil. Mean arterial pressure (MAP) and heart rate (HR) were measured before, 5, 10, 20, and 30 min after drug administration. Surgical field rating and blood loss were measured after surgery. Results : Heart rates at 10, 20, 30 minutes after continuous infusion of drug were lower in group R than in group N (P < 0.05). The time for the MAP to return to the baseline after discontinuation of drug infusion was shorter in group R than in group N (P < 0.05). There were no significant differences in the surgical field rating and blood loss between the groups. Conclusions : Remifentanil enabled controlled hypotension and provided good surgical conditions for orthognathic surgery with no need for additional use of a hypotensive agent.ope

Prediction of the Distance from Skin to Mid-Thoracic Epidural Space by Computed Tomography

BACKGROUND: Although thoracic epidural analgesia is a common practice in neuroaxial blockade for effective post-operative pain relief especially in major abdominal or thoracic surgery, difficult access to the thoracic epidural space is a frequent problem and can cause neurological complications like spinal cord injury and total spinal block. To minimize complications, we should to guess the distance for thoracic epidural space before this procedure. METHODS: One hundred fifty patients having preoperative upper abdominal computed tomography (CT) for diagnosis of their disease presented to major abdominal operation requiring mid-thoracic epidural analgesia for postoperative pain relief. The patient was placed in the sitting position and the levels of T7 and T8 spinous processes were identified. Using a paramedian approach with loss of resistance technique, when the insertion angles of Tuohy needle was measured by a protractor; inward angle (α) to the sagittal plane and downward angle (β) to the transverse section of the spine. Entry of the needle into the epidural space, actual length (A) of the needle was marked and then measured with a ruler. Reviewing the abdominal CT films using the Picture Archiving and Communication System (PACS), the distance (B) from epidural space to skin on the transverse CT plane was measured at the corresponding to T7-T8 seemed to the level of the lowest scapular. The estimated length (Ac) of the skin to the epidural space was calculated by principle of trigonometry with α, β and B. RESULTS: Mean (SD) age, height, weight, BMI were 56 (11) yr, 164 (6.9) cm, 61 (11.5) kg, and 37 (6.2) kg/m2, respectively. The A, B, Ac value and α, β were 5.4 (0.77), 4.3 (0.76), 5.4 (0.85), 12 (3.4)°, 33 (9.6)°. There were significant correlation of both actual length of the needle and the estimated distance on CT film. Actual length of the needle tended to have 1.25 times longer than the estimated distance on CT film. There were also significances both A and weight, BMI, but not age, height. CONCLUSIONS: The distance from epidural space to skin measured on the transverse CT plane may be helpful as a guide for mid-thoracic epidural catheter insertion.ope

Cerebral Oxygenation during Laparoscopic Surgery: Jugular Bulb versus Regional Cerebral Oxygen Saturation

PURPOSE: We hypothesized that regional cerebral oxygen saturation (rSO2) could replace jugular bulb oxygen saturation (SjvO2) in the steep Trendelenburg position under pneumoperitoneum. Therefore, we evaluated the relationship between SjvO2 and rSO2 during laparoscopic surgery. MATERIALS AND METHODS: After induction of anesthesia, mechanical ventilation was controlled to increase PaCO2 from 35 to 45 mm Hg in the supine position, and the changes in SjvO2 and rSO2 were measured. Then, after establishment of pneumoperitoneum and Trendelenburg position, ventilation was controlled to maintain a PaCO2 at 35 mm Hg and the CO2 step and measurements were repeated. The changes in SjvO2 (rSO2) -CO2 reactivity were compared in the supine position and Trendelenburg-pneumoperitoneum condition, respectively. RESULTS: There was little correlation between SjvO2 and rSO2 in the supine position (concordance correlation coefficient=0.2819). Bland-Altman plots showed a mean bias of 8.4% with a limit of agreement of 21.6% and -4.7%. SjvO2 and rSO2 were not correlated during Trendelenburg-pneumoperitoneum condition (concordance correlation coefficient=0.3657). Bland-Altman plots showed a mean bias of 10.6% with a limit of agreement of 23.6% and -2.4%. The SjvO2-CO2 reactivity was higher than rSO2-CO2 reactivity in the supine position and Trendelenburg- pneumoperitoneum condition, respectively (0.9 ± 1.1 vs. 0.4 ± 1.2% mm Hg(-1), p=0.04; 1.7 ± 1.3 vs. 0.5 ± 1.1% mm Hg(-1), p<0.001). CONCLUSION: There is little correlation between SjvO2 and rSO2 in the supine position and Trendelenburg-pneumoperitoneum condition during laparoscopic surgery.ope

The effect of epidural sufentanil in ropivacaine on urinary retention in patients undergoing gastrectomy

BACKGROUND: Although epidural opioids have excellent analgesic property, their side-effects limit its use in patient-controlled epidural analgesia (PCEA). This study was designed to compare side-effects of epidural sufentanil in ropivacaine with that of morphine in ropivacaine focusing on lower urinary tract function after major abdominal surgery. METHODS: In total 60 patients undergoing gastrectomy were randomly allocated to receive either sufentanil in ropivacaine (Group S, n=30) or morphine in ropivacaine (Group M, n=30) for their PCEA. Epidural catheter was inserted between the 7th and 8th thoracic spine. Visual analogue pain score and side-effects such as nausea, vomiting, pruritus, hypotension and urinary retention were evaluated during postoperative days (PODs) 1 and 2 in the postanaesthetic care unit. RESULTS: The incidence of serious to major micturition problem in Group S was lower than that in Group M (P<0.001). The incidence of pruritus, nausea and vomiting was also lower in Group S than in Group M on POD 1. CONCLUSIONS: The lower incidence of major/serious micturition problem in patients receiving sufentanil in ropivacaine thoracic epidural analgesia suggests that continuation of urinary drainage may not be necessary from POD 1 onwards.ope

Spinal anesthesia with isobaric tetracaine in patients with previous lumbar spinal surgery

PURPOSE: Previous lumbar spinal surgery (PLSS) is not currently considered as a contraindication for regional anesthesia. However, there are still problems that make spinal anesthesia more difficult with a possibility of worsening the patient's back pain. Spinal anesthesia using combined spinal-epidural anesthesia (CSEA) in elderly patients with or without PLSS was investigated and the anesthetic characteristics, success rates, and possible complications were evaluated. MATERIALS AND METHODS: Fifty patients without PLSS (Control group) and 45 patients with PLSS (PLSS group) who were scheduled for total knee arthroplasty were studied prospectively. A CSEA was performed with patients in the left lateral position, and 10 mg of 0.5% isobaric tetracaine was injected through a 27 G spinal needle. An epidural catheter was then inserted for patient controlled analgesia. Successful spinal anesthesia was defined as adequate sensory block level more than T12. The number of skin punctures and the onset time were recorded, and maximal sensory block level (MSBL), time to 2-segment regression, success rate and complications were observed. RESULTS: The success rate of CSEA in Control group and PLSS group was 98.0%, and 93.3%, respectively. The median MSBL in PLSS group was higher than Control group [T4 (T2-L1) vs. T6 (T3-T12)] (p < 0.001). There was a significant difference in the number of patients who required ephedrine for the treatment of hypotension in PLSS group (p = 0.028). CONCLUSION: The success rate of CSEA in patients with PLSS was 93.3%, and patients experienced no significant neurological complications. The MSBL can be higher in PLSS group than Control group.ope

Fiberoptic Bronchoscopic Treatment of Pulmonary Aspiration Occurring in a Child during Induction of Anesthesia: A case report

Pulmonary aspiration of gastric contents is a very rare but one of the most feared complications of anesthesia. The risk factors are gastroesophageal reflux, previous aspiration, renal failure, difficult intubation and trauma. The incidence of aspiration during anesthesia of children has been reported to be more common than adults. This report describes the case of a 7-year-old female patient who had experienced pulmonary aspiration during induction of anesthesia. With fiberoptic brochoscopy, the aspirates in both bronchi were carefully suctioned, and the following chest X-ray and blood gas findings improved. She was transferred to the intensive care unit for respiratory support and showed no further problems.ope