• Neonatal Medicine
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• v.25 no.2
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• pp.78-84
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• 2018

Purpose: To investigate the hemodynamic risk factors for necrotizing enterocolitis (NEC), we analyzed the characteristics of descending aorta (DA) blood flow in preterm neonates, who later developed NEC. Methods: This was an observational case-control study on 53 preterm neonates at a tertiary referral center. Clinical and echocardiographic data were collected from 23 preterm neonates with NEC (NEC group), and compared with those of 30 preterm neonates without NEC (control group). Echocardiography was done at a median (interquartile range) of 5 (3-9) days after birth and 2 (1-2.5) days before the diagnosis of NEC. Results: Basic clinical characteristics including gestational age, birth weight, Apgar score, breast feeding status, use of umbilical catheters, and mode of invasive ventilator care were similar between the groups. Compared with the control group, the lowest diastolic velocity of DA was significantly decreased, whereas the diastolic reverse flow and the ratio of diastolic reverse to systolic forward flows were significantly increased in the NEC group. In addition, the resistive index (RI) of DA was significantly increased in the NEC group and showed a positive association with the development of NEC. Multivariate logistic regression analysis showed that increasing RI of DA was an independent risk factor for the development of NEC (P=0.008). Conclusion: Significant changes in DA flow characteristics including decreased diastolic velocity and increased diastolic reverse flow along with increased peripheral vascular resistance were observed before the development of NEC in preterm neonates. These findings may help clinicians stratify in advance neonates at a risk of developing NEC and may help improve outcomes in these neonates.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.927-932
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• 2013

The intracranial aneurysm model is extracted based on the Computed Tomography (CT) scan images. Computational fluid dynamics simulations were conducted under both steady and realistic flow conditions in ANSYS-FLUENT. The minimum wall shear stress in the intracranial aneurysm tended to occur in the aneurysmal region. The magnitude of wall shear stress along inner wall of the curvature in the right M1 segment of middle cerebral artery is approximately 20 times higher than that along both the proximal and distal walls. However, the magnitudes of the wall shear stress at the aneurysm region were considerably low. The blood flow has the complex distribution in the aneurysmal region during the systolic period. Complex helical flow patterns are observed inside the aneurysm. Through an analysis of the hemodynamic characteristics, one may predict the rupture of the cerebral aneurysms.

• Journal of The Korean Society of Clinical Toxicology
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• v.10 no.1
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• pp.1-7
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• 2012

Purpose: Herbal preparations have long been used for medical purposes by traditional cultures, and their use is increasing in modern societies. However, many herbal agents produce specific cardiovascular toxicities in humans. We performed this study in order to investigate the clinical characteristics of the cardiac toxicities associated with herbal remedies. Methods: We conducted a retrospective study of 45 patients (mean age $57{\pm}10$ years) who presented with cardiotoxicity between January 2007 and May 2011 due to ingestion of herbal remedy substances. Patients were identified as suffering cardiotoxicity if they presented with chest pain, EKG abnormality, and elevation of cardiac enzyme. Results: Of the 45 total cases, 17 included hemodynamic instability (37.8%), 7 with increasing cardiac enzyme (15.6%), 2 with cardiac arrest (4.4%) and one case of mortality (2.2%). The cardiotoxic herb group that demonstrated the worst clinical course was Ranunculaceae. Conclusions: In our study results, 57.6% of the herbal intoxication patients demonstrated the effects of cardiotoxicity. Thus, we recommend careful monitoring of herbal intoxication patients.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1989-1990
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• 2008

한의학에서 맥진은 한의사가 손가락으로 환자의 손목의 요골동맥을 짚어 맥박이 손가락에 닿는 느낌에 근거하여 병세를 감별하는 진찰방법으로 인체의 건강상태를 살피고, 정상인의 평맥(平脈)으로부터 환자의 병맥(病脈)을 분석하는 진단법이다. 손목에 있는 요골 경상돌기(styloid preocess) 부근의 볼록한 지점을 고골(高骨)이라하는데 이 돌기를 기준으로 맥이 느껴지는 위치를 검지, 중지, 약지를 이용해 진맥위치를 잡는다. 맥진 시 한의사는 맥진위치에 압력을 서서히 가하면서 손끝에 느껴지는 감각을 이용해 진단한다. 이 과정에서 맥진위치 요골동맥의 혈관이 서서히 occlusion 된다. 본 논문에서는 맥진과정 시 요골동맥의 혈류역학적인 변화를 초음파를 이용해 분석해보고자 한다. 건강한 남자 피험자(34세)를 대상으로 초음파 장비(Voluson 730Pro, GE Medical, U.S.)를 이용해 맥진 위치의 혈관특성을 관찰한다. 혈압계를 이용해 혈관에 압력을 0에서 130mmHg까지 10mmHg씩 단계별로 가압한 후 초음파를 측정한다. 그 결과, 요골동맥에 압력을 가할수록 혈류속도가 서서히 감소함을 알 수 있었으며, 회귀식을 분석할 수 있었다(y = -0.3509x +44.323, $R^2$ = 0.9547). 또한, 가압 단계를 0$\sim$10mmHg, 20$\sim$40mmHg, 50$\sim$70mmHg, 80$\sim$100mmHg 110$\sim$130mmHg으로 가압단계를 나누어 보면, 각 단계별로는 42.32cm/sec, 33.08cm/sec, 24.8cm/sec, 14.3cm/sec, 0cm/sec로 혈류속도가 변화를 보였다. 각 단계별로 혈류속도가 평균 10.58cm/sec의 차이를 보임을 알 수 있다. 본 연구를 통해 가압력에 대한 맥진위치의 혈류변화를 관찰하였다. 그러나 직접 맥진위치를 가압하면서 초음파를 통해 혈류속도를 측정할 수 있는 방법이 없어, 맥진 위치 바로 위쪽을 가압하고 초음파 측정을 하였다. 직접 혈관을 가압하고 그때의 혈류속도를 측정하면 보다 정확히 맥진시의 혈류역학적 특성을 분석할 수 있을 것으로 판단된다. 장비의 고안을 통해 다음 연구에서는 직접적인 가압 후 혈슈속도를 측정해 봄으로써 본 결과와 비교 분석해 보고자 한다.

• Journal of Trauma and Injury
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• v.22 no.2
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• pp.254-259
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• 2009

Purpose: Pelvic trauma is a serious skeletal injury with high mortality. Especially in cases of severe injury trauma, treatment outcomes depend on early diagnosis and intervention. We expect trauma surgeon to play an important role in the management of severe multiple trauma patients. Methods: A retrospective study was performed on pelvic trauma patients with hemodynamic instability between March 2005 and September 2009. We divided the time period into period I (March 2005~Feburary 2009) and period II (March 2009~September 2009). The trauma surgeon and team started to work from period II. Data were collected regarding demographic characteristics, mechanism of injury, type of pelvic fracture, ISS(injury severity score), treatment modality, transfusion requirement, time to definitive treatment, and mortality. Results: During period I, among 7 hemodynamically unstable patients, 4(57.1%) patients died. However during Period II, only one of 6(16.6%) patients died. The demographic data and injury scores showed no differences between the two time periods, but the time to definitive treatment was very short with trauma team intervention(14.4 hrs vs. 3.9 hrs). Also, the amount of transfusion was less(41.1 U vs. 13.9 U). With arterial embolization, early pelvic external fixation led to less transfusion and made patients more stable. Conclusion: This study demonstrated the importance of the trauma surgeon and the trauma team in cases of hemodynamically unstable pelvic trauma. Even with the same facility and resources, an active trauma team approach can increase the survival of severely injured multiple trauma patients.

• The Korean Journal of Pain
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• v.10 no.2
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• pp.166-169
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• 1997

Background: We have noted a high incidence of vasovagal episodes associated with use of interscalene block(ISB) for shoulder arthroscopy in the sitting position. The purpose of this retrospective study is to alert the possibility of potentially dangerous vasovagal events, describe the characteristics of this problem, and propose therapeutic devices. Methods: Results 62 patients who underwent shoulder arthroscopy in the sitting position with ISB were retrospectively analyzed. Group 1, 10 patients experienced vasovagal events characterized by sudden hypotension and bradycardia. Remaining 52 patients, Group 2, did not experience these symptoms. All patient charts were reviewed for age, sex, side of surgery, premedication, preoperative fluid and intraoperative medications. Perioperative hemodynamic changes were also compared between the two groups. Results: Vasovagal events experienced in 16% of patients(10/62) and occurred $39{\pm}18$ min after sitting position and $22{\pm}18$ min after start of operation. Number of patients who receiving anticholinergics for premedication were significantly lower in Group 1 than Group 2(2/10 vs. 28/52, p<0.05). Conclusions: Bezold-parish reflex is a potential mechanism for sudden hypotension and bradycardia which can occur during shoulder arthroscopy in sitting position. Therefore anticholinergic pretreatment and meticulous monitoring during operation are recommended to prevent B-J reflex.

• Journal of Korean Biological Nursing Science
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• v.9 no.1
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• pp.85-102
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• 2007

Purpose: Knowledge on pathophysiology is important to understand diseases and patient conditions and also in providing advanced nursing care. This study was performed to investigate the present situation, knowledge, and educational need on pathophyiology of advanced practice nurses(APN). Method: Eighty-four APN, who is practicing in hospitals nationwide, were surveyed with structured questionnaires developed by researchers. The questionnaire were composed of 109 items with 4 point scales with the contents of general characteristics, educational experience on pathophyisology, educational need, and knowledge on major and subcategories of pathophysiology. Result: The 77.1% of APN had experience of taking pathophysiology lecture and the lecturer were mainly medical doctors(39.8%) and APN(32.4%). The 61.5% of APN answered that the knowledge on pathophysiology was helpful and 97.6% of APN thought pathphysiologic education is needed in clinical practice. Seven major categories of pathophysiology showed higher scores were water imbalance, heart diseases, hemodynamic disorders, arterial vessel disorders, electrolyte imbalance, diseases of the digestive system, and diseases of the respiratory systems. Educational needs on the major and subcategories of pathphysiology were different by the field of APN and also by the clinical experiences as APN. APN also responded that there is a necessity to change the present curricular more specific to each practice field and more focus on the clinical practice. Conclusion: It was confirmed that educational and clinical need on the pathophysiology is very high and there is urgent need to change current curricular more specific to the field of APN and also clinical practice. This survey will help to identify and clarify the areas of change and to improve the education for the APN.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1191-1198
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• 2011

The use of a ventricular assist device (VAD) can raise the one-year survival rate without cardiac transplantation from 25% to 52%. However, malfunction of the VAD system causes 6% of VAD patients' deaths, which could possibly be avoided through the development of new VADs in which VAD malfunctions do not affect the patient's heart movement or hemodynamic state. A conventional VAD has an impeller or vane for propelling blood that can allow blood to regurgitate when the propelling force is weaker than the aortic pressure. In this paper, we developed a new pulsatile conduit-shaped VAD that has two valves. This device removes the possibility of blood regurgitation and has a small stationary area even when the pumping force is extremely weak. We estimated the characteristics of the device by measuring the outflow and the pressure of the pump in in-vitro and in-vivo experiments.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.82-83
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• 1996

In this paper, we present a simplified model for complicance determination of the moving-actuator type totally implantable artificial heart (TAH). The modeling equations are derived from the mechanics and geometry of the TAH components. The interventricular pressure and volume are computed for determining the compliance of the interventricular space using this model. The model is capable of generating realistic hemodynamic variables such as the left atrial pressure and interventricular pressure and is proved to be acceptable. This model can be used as an initial step for analyzing characteristics of the moving-actuator type TAH.

• Journal of Chest Surgery
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• v.54 no.1
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• pp.31-35
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• 2021

Background: Arteriovenous fistula (AVF) for hemodialysis is essential for patients with end-stage renal disease. However, it is difficult to maintain AVF reliably. It is vitally important to select proper blood vessels for AVF formation. In a previous study, a minimum diameter of 3 mm for the autologous vein was proposed. However, patients who did not meet the minimum vascular diameter before anesthesia, but fulfilled other criteria, showed satisfactory venous dilatation after brachial plexus block (BPB). This study investigated the extent of vein expansion by BPB and the surgical outcomes of dilated veins after BPB. Methods: Sixty-one patients who underwent AVF formation using an autologous vein between August 2018 and December 2019 were included in the study. The clinical characteristics of the patient groups, hemodynamic parameters including the diameter of blood vessels before and after BPB, and complications were investigated. Based on the venous diameter measured by sonography before anesthesia, patients were divided into group A (26 patients) and group B (35 patients), with venous diameters <3 mm and ≥3 mm, respectively. Results: The venous diameter expanded after anesthesia by 41% overall, by 62% in group A, and by 25% in group B. This difference between groups A and B was statistically significant (p=0.001). No other variables showed statistically significant differences. Conclusion: Sufficient venous dilatation was observed after BPB. Therefore, if the vein is sufficiently dilated after BPB, even in patients with a pre-anesthesia venous diameter <3 mm, surgery may still be performed with an expected desirable outcome.