• Journal of Chest Surgery
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• v.37 no.1
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• pp.1-10
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• 2004

Background: Currently, the cardiopulmonary machine with non-pulsatile pumps, which are low in internal circuit pressure and cause little damage to blood cells, is widely used. However, a great number of experimental studies shows that pulsatile perfusions are more useful than non-pulsatile counterparts in many areas, such as homodynamic, metabolism, organ functions, and micro-circulation. Yet, many concerns relating to pulsatile cardiopulmonary machines, such as high internal circuit pressure and blood cell damage, have long hindered the development of pulsatile cardiopulmonary machines. Against this backdrop, this study focuses on the safety and effectiveness of the pulsatile cardiopulmonary machines developed by a domestic research lab. Material and Method: The dual-pulsatile cardiopulmonary bypass experiment with total extracorporeal circulation was conducted on six calves, Extracorporeal circulation was provided between superior/inferior vena cava and aorta. The membrane oxygenator, which was placed between the left and right pumps, was used for blood oxygenation. Circulation took four hours. Arterial blood gas analysis and blood tests were also conducted. Plasma hemoglobin levels were calculated, while pulse pressure and internal circuit pressure were carefully observed. Measurement was taken five times; once before the operation of the cardiopulmonary bypass, and after its operation it was taken every hour for four hours. Result: Through the arterial blood gas analysis, PCO2 and pH remained within normal levels. PO2 in arterial blood showed enough oxygenation of over 100 mmHg. The level of plasma hemoglobin, which had total cardiopulmonary circulation, steadily increased to 15.87 $\pm$ 5.63 after four hours passed, but remained below 20 mg/㎗. There was no obvious abnormal findings in blood test. Systolic blood pressure which was at 97.5$\pm$5.7 mmHg during the pre-circulation contraction period, was maintained over 100 mmHg as time passed. Moreover, diastolic blood pressure was 72.2 $\pm$ 7.7 mmHg during the expansion period and well kept at the appropriate level with time passing by. Average blood pressure which was 83$\pm$9.2 mmHg before circulation, increased as time passed, while pump flow was maintained over 3.3 L/min. Blood pressure fluctuation during total extracorporeal circulation showed a similar level of arterial blood pressure of pre-circulation heart. Conclusion: In the experiment mentioned above, pulsatile cardiopulmonary machines using the doual-pulsatile structure provided effective pulsatile blood flow with little damage in blood cells, showing excellence in the aspects of hematology and hemodynamic. Therefore, it is expected that the pulsatile cardiopulmonary machine, if it becomes a standard cardiopulmonary machine in all heart operations, will provide stable blood flow to end-organs.

• Journal of computational fluids engineering
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• v.20 no.2
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• pp.88-95
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• 2015

Blood pump analysis process includes both mechanical and bio-mechanical aspects. Since a blood pump is a mechanical device, it has to be mechanically efficient. On the other hand, blood pumps function is sensitively related to the blood recirculation; hence, bio-factors such as hemolysis and thrombosis become important. This paper numerically investigates the mechanical and bio-mechanical performances of the Rotaflow in the extracorporeal membrane oxygenation(ECMO), Ventricular Assist Device(VAD), and full-load conditions. The operational conditions are defined as(400[mmHg], 5[L/min.]), (100[mmHg], 3[L/min.]), and (600[mmHg], 10[L/min.]) for ECMO, VAD, and full-load conditions, respectively. The results are presented and analyzed from the mechanical aspect via performance curves, and from bio-mechanical aspect via focusing on hemolytic characteristics. Regions of top and bottom cavities show recirculation in both ECMO and VAD condtions. In addition, Eulerian-based calculation of modified index of hemolysis(MIH) has been investigated. The results demonstrate that the VAD condition has the least risk of hemolysis among the others, while the full-load condition has the highest risk.

• Neonatal Medicine
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• v.25 no.3
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• pp.102-108
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• 2018

Purpose: Congenital diaphragmatic hernia (CDH) is rare but potentially fatal. The overall outcome is highly variable. This study aimed to identify a simple and dynamic parameter that helps predict the mortality of CDH patients in real time, without invasive tests. Methods: We conducted a retrospective chart review of 59 CDH cases. Maternal and fetal information included the gestational age at diagnosis, site of defect, presence of liver herniation, and lung-to-head ratio (LHR) at 20 to 29 weeks of gestational age. Information regarding postnatal treatment, including the number of days until surgery, the need for inhaled nitric oxide (iNO), the need for extracorporeal membrane oxygenation (ECMO), and survival, was collected. The highest respiratory severity score (RSS) within 24 hours after birth was also calculated. Results: Statistical analysis showed that a younger gestational age at the initial diagnosis (P<0.001), a lower LHR (P=0.001), and the presence of liver herniation (P=0.003) were prenatal risk factors for CDH mortality. The RSS and use of iNO and ECMO were significant factors affecting survival. In the multivariate analysis, the only remaining significant risk factor was the highest preoperative RSS within 24 hours after birth (P=0.002). The area under the receiver operating characteristic curve was 0.9375, with a sensitivity of 91.67% and specificity of 83.87% at the RSS cut-off value of 5.2. The positive and negative predictive values were 82.14% and 92.86%, respectively. Conclusion: Using the RSS as a prognostic predictor with simple calculations will help clinicians plan CDH management.

• Journal of Chest Surgery
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• v.46 no.1
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• pp.41-48
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• 2013

Background: We present our 12-year experience of pulmonary thromboendarterectomy in patients with chronic thromboembolic pulmonary hypertension. Materials and Methods: Between January 1999 and March 2011, 16 patients underwent pulmonary thromboendarterectomy. Eleven patients (69%) were classified as functional class III or IV based on the New York Heart Association (NYHA) classification. Seven patients had a history of inferior vena cava filter insertion, and 5 patients showed coagulation disorders. Pulmonary thromboendarterectomy was performed during total circulatory arrest with deep hypothermia in 14 patients. Results: In-hospital mortality and late death occurred in 2 patients (12.5%) and 1 patient (6.3%), respectively. Extracorporeal membrane oxygenation support was required in 4 patients who developed severe hypoxemia after surgery. Thirteen of the 14 survivors have been followed up for 54 months (range, 2 to 141 months). The pulmonary arterial systolic pressure and cardiothoracic ratio on chest radiography was significantly decreased after surgery ($76{\pm}26$ mmHg vs. $41{\pm}17$ mmHg, p=0.001; $55%{\pm}8%$ vs. $48%{\pm}3%$, p=0.003). Tricuspid regurgitation was reduced from $2.1{\pm}1.1$ to $0.7{\pm}0.6$ (p=0.007), and the NYHA functional class was also improved to I or II in 13 patients (81%). These symptomatic and hemodynamic improvements maintained during the late follow-up period. Conclusion: Pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension shows good clinical outcomes with acceptable early and long term mortality.

• Journal of Chest Surgery
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• v.43 no.3
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• pp.312-315
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• 2010

Infection of both native and prosthetic vessels in the groin is a very serious disease because of recurrent arterial rupture and sepsis, which can cause death. The successful treatment of groin infection, including infection of the femoral artery, requires extensive excision of the infected tissues and restoration of the circulation where the infected area is isolated. Here we describe a case of obturator bypass in a patient with infected femoral artery rupture that occurred after extracorporeal membrane oxygenation for myocarditis and severe heart failure.

• Communications for Statistical Applications and Methods
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• v.24 no.6
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• pp.561-581
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• 2017

Bayesian statistics can play a key role in the design and analysis of clinical trials and this has been demonstrated for medical device trials. By 1995 Bayesian statistics had been well developed and the revolution in computing powers and Markov chain Monte Carlo development made calculation of posterior distributions within computational reach. The Food and Drug Administration (FDA) initiative of Bayesian statistics in medical device clinical trials, which began almost 20 years ago, is reviewed in detail along with some of the key decisions that were made along the way. Both Bayesian hierarchical modeling using data from previous studies and Bayesian adaptive designs, usually with a non-informative prior, are discussed. The leveraging of prior study data has been accomplished through Bayesian hierarchical modeling. An enormous advantage of Bayesian adaptive designs is achieved when it is accompanied by modeling of the primary endpoint to produce the predictive posterior distribution. Simulations are crucial to providing the operating characteristics of the Bayesian design, especially for a complex adaptive design. The 2010 FDA Bayesian guidance for medical device trials addressed both approaches as well as exchangeability, Type I error, and sample size. Treatment response adaptive randomization using the famous extracorporeal membrane oxygenation example is discussed. An interesting real example of a Bayesian analysis using a failed trial with an interesting subgroup as prior information is presented. The implications of the likelihood principle are considered. A recent exciting area using Bayesian hierarchical modeling has been the pediatric extrapolation using adult data in clinical trials. Historical control information from previous trials is an underused area that lends itself easily to Bayesian methods. The future including recent trends, decision theoretic trials, Bayesian benefit-risk, virtual patients, and the appalling lack of penetration of Bayesian clinical trials in the medical literature are discussed.

• Journal of Chest Surgery
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• v.34 no.4
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• pp.356-360
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• 2001

일시적 혹은 단기간의 심폐보조는 여러 형태의 심부전에서 널리 이용되어 왔다. 이 중 체외막산소화장치는 고식적 치료에 반응없는 환자에서 주로 사용되는데, 소아에서는 자주 이용되어 왔으나 성인에서는 그 적응증이 명확하지 않았으며 결과도 만족스럽지 못했다. 환자는 승모판 협착증을 가진 32세의 여자로 제왕절개술후 발생한 폐부종으로 내원하였다. 내원시 환자는 쇽상태로 강심제, 폐혈관확장제, 이뇨제등에 반응이 없었다. 우측 대퇴정-동맥캐뉼라를 통하여 14시간동안 체외막산소화장치를 이용하였으며, 환자상태는 가동 즉시 호전을 보였다. 이후 양측판막치환술을 시행하였고 수술 후에도 체외막산호화장치를 지속하였다. 체외막산호화장치는 수술시간을 포함하여 모두 62시간동안 가동하였으며, 이탈(weaning)은 안정된 혈류역학, 호전된 폐부종, 기저질환의 교정등을 통하여 성공적으로 이루어졌다. 환자는 판막수술 후 30일째 특별한 합병증없이 퇴원하였다.

• Tuberculosis and Respiratory Diseases
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• v.84 no.3
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• pp.217-225
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• 2021

Background: Despite the proven benefits of dexamethasone in hospitalized coronavirus disease 2019 (COVID-19) patients, the optimum time for the administration of dexamethasone is unknown. We investigated the progression of COVID-19 pneumonia based on the timing of dexamethasone administration. Methods: A single-center, retrospective cohort study based on medical record reviews was conducted between June 10 and September 21, 2020. We compared the risk of severe COVID-19, defined as the use of a high-flow nasal cannula or a mechanical ventilator, between groups that received dexamethasone either within 24 hours of hypoxemia (early dexamethasone group) or 24 hours after hypoxemia (late dexamethasone group). Hypoxemia was defined as room-air SpO₂ <90%. Results: Among 59 patients treated with dexamethasone for COVID-19 pneumonia, 30 were in the early dexamethasone group and 29 were in the late dexamethasone group. There was no significant difference in baseline characteristics, the time interval from symptom onset to diagnosis or hospitalization, or the use of antiviral or antibacterial agents between the two groups. The early dexamethasone group showed a significantly lower rate of severe COVID-19 compared to the control group (75.9% vs. 40.0%, p=0.012). Further, the early dexamethasone group showed a significantly shorter total duration of oxygen supplementation (10.45 days vs. 21.61 days, p=0.003) and length of stay in the hospital (19.76 days vs. 27.21 days, p=0.013). However, extracorporeal membrane oxygenation and in-hospital mortality rates were not significantly different between the two groups. Conclusion: Early administration of dexamethasone may prevent the progression of COVID-19 to a severe disease, without increased mortality.

• Health Policy and Management
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• v.31 no.4
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• pp.472-478
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• 2021

Background: Early identification of patients who are highly likely to develop severe illness among confirmed cases of coronavirus disease 19 (COVID-19) can be expected to lead to effective treatment. This study therefore aimed to determine whether the presence of nonalcoholic fatty liver disease (NAFLD) has an impact on the exacerbation of COVID-19 symptoms. Methods: The study used the Korean National Health Insurance claim data for treatment of COVID-19 patients in 2020. NAFLD includes nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). The outcome variables used were hospitalization and the use of medical devices. Hospitalization was defined by a length of stay exceeding one day and the use of medical devices was defined as one or more uses of a ventilator or extracorporeal membrane oxygenation. Multivariable logistic regression analysis was performed to determine if there was a difference in the hospitalization and use of medical devices of COVID-19 patients depending on the presence of NAFLD. Results: The odds ratio of hospitalization was 1.059, indicating slightly higher odds of hospitalization for patients with NAFL or NASH compared to those without the conditions, but it was not statistically significant (0.969-1.156). On the other hand, the odds ratio of use of medical devices was high at 1.667 and was statistically significant (1.111-2.501). Conclusion: The study results found NAFLD to be a risk factor that can exacerbate symptoms in COVID-19 patients. Accordingly, it is necessary to identify NAFLD patients through preemptive screening and provide them with appropriate treatments.

• Journal of Chest Surgery
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• v.52 no.5
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• pp.335-341
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• 2019

Background: The endovascular approach to aortic disease treatment has been increasingly utilized in the past 2 decades. This study aimed to determine the long-term results of using the Seal thoracic stent graft. Methods: We retrospectively reviewed the outcomes of patients who underwent thoracic endovascular aortic repair or a hybrid procedure using the Seal thoracic stent graft (S&G Biotech, Seongnam, Korea) from January 2008 to July 2018 at a single institution. We investigated in-hospital mortality and the incidence of postoperative complications. We also investigated the mid-term survival rate and incidence of aorta-related complications. Results: Among 72 patients with stent grafts, 15 patients underwent the hybrid procedure and 21 underwent emergency surgery. The mean follow-up period was $37.86{\pm}30.73$ months (range, 0-124 months). Five patients (6.9%) died within 30 days. Two patients developed cerebrovascular accidents. Spinal cord injury occurred in 2 patients. Postoperative renal failure, postoperative extracorporeal membrane oxygenation support, and pneumonia were reported in 3, 1, and 6 patients, respectively. Stent-related aortic complications were observed in 5 patients (6.8%). The 1- and 5-year survival and freedom from stent-induced aortic event rates were 81.5% and 58.7%, and 97.0% and 89.1%, respectively. Conclusion: The use of the Seal thoracic stent graft yielded good mid-term results. Further studies are needed to examine the long-term outcomes of this device.