• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.281-286
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• 2003

Blood Pressure is one of the most fundamental Parameters which reflects physical conditions medically and the blood pressure measurement system using oscillometric method is a Non-Invasive Blood Pressure measurement device by measuring arterial Pressure through a cuff. In this paper. we designed a inflatable wrist blood pressure system which measures blood Pressure during the stepping inflation in the wrist cuff. The hardware system consists of a main power unit, a bladder in cuff unit, signal detection units, signal Processing units. a wireless data transmission unit, and a data display unit. We evaluated the reliability of this system by comparing and analyzing systolic. diastolic blood Pressure, and heart rate with other commercial blood Pressure measurement devices. Characteristic ratio values used to determine systolic and diastolic blood Pressure using MAA(Maximum Amplitude Algorithm) were 0.436 and 0.671 respectively.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2919-2922
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• 2003

In this paper, we present a new methodology to analyze the characteristics of artery by using 4 channels photophethysmography. The proposed parameter is a time difference of pulse transit time (PTT) between pulse waves at finger site and at toe site. As the results of experiments, the change of parameter was found according to ages. The result of regression analysis about relationships between the parameter and ages for n=51, the coefficient of correlation of non-normalized data has -0.79770 in left side and -0.80599 in right side and the coefficient of correlation of normalized data by height has -0.81345 in left side and -0.81605 in right side.

• Journal of Biomedical Engineering Research
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• v.31 no.1
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• pp.14-19
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• 2010

Baroreflex sensitivity (BRS) is a parameter of the cardiovascular system that is reflected in changes in pulse interval (PD and systolic blood pressure (SBP). BRS contains information about how the autonomic nervous system regulates hemodynamic homeostasis. Normally the beat-to-beat SBP measurement and the pulse interval measured from the electrocardiogram (ECG) are required to estimate the BRS. We investigated the possibility of measuring BRS in the absence of a beat-to-beat SBP measurement device. Pulse arrival time (PAT), defined as the time between the R-peak of the ECG and a single characteristic point on the pulse wave recorded from any arterial location was measured by photoplethysmography. By comparing the BRS obtained from conventional measurements with our method during controlled breathing, we confirmed again that PAT and SBP are closely correlated, with a correlation coefficient of -0.82 to -0.95. The coherence between SBP and PI at a respiration frequency of 0.07-0.12 Hz was similar to the coherence between PAT and PI. Although the ranges and units of measurement are different (ms/mmHg vs. ms/ms) for BRS measured conventionally and by our method, the correlation is very strong. Following further investigation under various conditions, BRS can be reliably estimated without the inconvenient and expensive beat-to-beat SBP measurement.

• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.189-194
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• 1992

As people's income and intake of animal fat rapidly increase, so does choresterol concentration in blood. Thus diseases such as non-insulin-dependent diabetes mellitus(NIDDM)myocardial infraction, high blood pressure, cerebral stroke resulting from atherosclerosis rapidly increase recently. It is very difficult to diagnose atherosclerosis early since its progress is so slow and there is no sypmtoms in the beginning of the disease. In this study a mechanical characteristic, compliance, of the lower leg arteries was measured noninvasively. Changes of blood volume and pressure were measured using impedance plethysmgraphy and mercury sphygmomanometer, respectively. The compliance was calculated by dividing the change of blood volume by the change of pulse pressure ( systolic-diastolic pressure ) . Subjects were 24 asymptomatic persons ranging (rom 30 Ic 58yeras and 14 diabetics from 41 to 59years. The compliances, mean, and systolic pressures were statistically analyzed using a t-test be- tween the healthy and diabetic groups. The average compliance of the healthy and diabetic group was measured 2.79 and 1.82U1/mmHg/cm, respectively and these were significantly different(p<0.01). It was also found that the compliance is a better parameter in differentiating the vascular disease than mean or systolic blood pressure.

• Korean Journal of Radiology
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• v.20 no.6
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• pp.863-879
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• 2019

Hepatocellular carcinoma (HCC) can be noninvasively diagnosed on the basis of its characteristic imaging findings of arterial phase enhancement and portal/delayed "washout" on computed tomography (CT) and magnetic resonance imaging (MRI) in cirrhotic patients. However, different specific diagnostic criteria have been proposed by several countries and major academic societies. In 2018, major guideline updates were proposed by the Association for the Study of Liver Diseases, European Association for the Study of the Liver (EASL), Korean Liver Cancer Association and National Cancer Center (KLCA-NCC) of Korea. In addition to dynamic CT and MRI using extracellular contrast media, these new guidelines now include magnetic resonance imaging (MRI) using hepatobiliary contrast media as the first-line diagnostic test, while the KLCA-NCC and EASL guidelines also include contrast-enhanced ultrasound (CEUS) as the second-line diagnostic test. Therefore, hepatobiliary MR contrast media and CEUS will be increasingly used for the noninvasive diagnosis and staging of HCC. In this review, we discuss the emerging role of hepatobiliary phase MRI and CEUS for the diagnosis of HCC and also review the changes in the HCC diagnostic criteria in major guidelines, including the KLCA-NCC practice guidelines version 2018. In addition, we aimed to pay particular attention to some remaining issues in the noninvasive diagnosis of HCC.

• Journal of Chest Surgery
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• v.55 no.2
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• pp.143-150
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• 2022

Background: The effectiveness of extracorporeal membrane oxygenation (ECMO) for patients with refractory cardiogenic shock or cardiac arrest is being established, and serum lactate is well known as a biomarker of end-organ perfusion. We evaluated the efficacy of pre-ECMO lactate for predicting 6-month survival in patients with acute coronary syndrome (ACS) undergoing ECMO. Methods: We reviewed the medical records of 148 patients who underwent veno-arterial (VA) ECMO for ACS between January 2015 and June 2020. These patients were divided into survivors and non-survivors based on 6-month survival. All clinical data before and during ECMO were compared between the 2 groups. Results: Patients' mean age was 66.0±10.5 years, and 116 (78.4%) were men. The total survival rate was 45.9% (n=68). Cox regression analysis showed that the pre-ECMO lactate level was an independent predictor of 6-month mortality (hazard ratio, 1.210; 95% confidence interval [CI], 1.064-1.376; p=0.004). The area under the receiver operating characteristic curve of pre-ECMO lactate was 0.64 (95% CI, 0.56-0.72; p=0.002; cut-off value=9.8 mmol/L). Kaplan-Meier survival analysis showed that the cumulative survival rate at 6 months was significantly higher among patients with a pre-ECMO lactate level of 9.8 mmol/L or less than among those with a level exceeding 9.8 mmol/L (57.3% vs. 31.8%, p=0.0008). Conclusion: A pre-ECMO lactate of 9.8 mmol/L or less may predict a favorable outcome at 6 months in ACS patients undergoing VA-ECMO. Further research aiming to improve the accuracy of predictions of reversibility in patients with high pre-ECMO lactate levels is essential.

• Journal of Chest Surgery
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• v.10 no.2
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• pp.281-294
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• 1977

Superior vena cava to pulmonary arterial shunting operation was made between the superior vena cava and the right pulmonary artery in the fashion of end-to-end anastomosis in 20 mongrel dogs. The experimental animals were divided into three group and blood flow in the superior vena cava was occluded for 20, 30 and 60 minutes respectively, and observations were made for the changes in caval pressure and cerebrospinal fluid pressure. And pathologic examinations were also performed. On occluding the caval blood flow, the superior vena caval pressure was sharply and immediately elevated from $103.5{\pm}19.8mmH_2O$ at thoracotomy to $556.4{\pm}86.lmmH_2O$ within 2 minutes to make its plateau thereafter, and the cerebrospinal fluid pressure followed closely the changes of the superior vena caval pressure in its level and pattern being elevated from $102.0{\pm}19.9mmH_2O$ to $490.5{\pm}79.9mmH_2O$. The drops of both the caval and cerebrospinal fluid pressures were definite and marked on opening the shunt flow through the anastomosis, but these postoperative pressures retained still higher ones above their levels measured at thoracotomy. The pathological examinations of the brain and the spinal cord were also performed in six animals. Characteristic changes uniformly seen in all area and in all animals were the findings of capillary congestion and perivascular edema. On the other hand, ischemic nerve cell changes were rather evident, revealing their degrees and extents being related to the prolongation of the time of caval occlusion which has followed by the sustained high pressures in both the superior vena and the cerebrospinal fluid. The experiment suggests the safety of this surgical procedure with minimal, if any, permanent damage as long as the occlusion of the caval blood flow is not prolonged beyond the expected.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1966_1967
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• 2009

As an attempt to characterize the pulse behaviors at the three pulse diagnosis positions in the oriental medicine which are called Chon, Gwan, and Cheok, we measure the pluse waveforms by SphygmoCor apparatus, that has been used widely for the evaluation of the arterial stiffness, and examine the Augmentation Index (AIx) at the aorta. For the study, twenty healthy men at the age of twenties have participated as the subject group. The pulse has been measured twice at the three palpation positions, and by two-way repeated measures ANOVA we tested the repeatability and the mean differences in the aortic AIx between Chon, Gwan, and Cheok. The AIx was found to be statistically different between the measurement positions. Duncan's test shows that the AIx is statistically different between Chon and the other two positions. Our study may be used as a reference for further scientific quantification of the pulse diagnosis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.678-681
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• 2007

In this study, an implementation of a system for measuring more accurate blood pressure by non-invasive methods of oscillometric was performed. The system were composed of pressure control, signal measurement, blood pressure signal processing units and wireless sensor network parts. For verify the validity of the system, tests of characteristics evaluations for pressure measurement unit, extraction of characteristic ratios for blood pressure estimation, blood pressure tracking by oscillometric method were performed. A group of five adult male was selected for the clinical test of the implemented system. The results of the oscillometric method in comparison with auscultatory method are that the maximum ratios of PAD of average, systolic and diastolic arterial pressure are 1.38%, 1.63% and 2.97% with SEP of 5.00, 3.72 and 4.34.

• Journal of Biomedical Engineering Research
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• v.33 no.3
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• pp.148-154
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• 2012

Hemorrhagic shock is a primary cause of deaths resulting from injury in the world. Although many studies have tried to diagnose accurately hemorrhagic shock in the early stage, such attempts were not successful due to compensatory mechanisms of humans. The objective of this study was to construct a survival prediction model of rats in acute hemorrhagic shock using a random forest (RF) model. Heart rate (HR), mean arterial pressure (MAP), respiration rate (RR), lactate concentration (LC), and peripheral perfusion (PP) measured in rats were used as input variables for the RF model and its performance was compared with that of a logistic regression (LR) model. Before constructing the models, we performed 5-fold cross validation for RF variable selection, and forward stepwise variable selection for the LR model to examine which variables were important for the models. For the LR model, sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (ROC-AUC) were 0.83, 0.95, 0.88, and 0.96, respectively. For the RF models, sensitivity, specificity, accuracy, and AUC were 0.97, 0.95, 0.96, and 0.99, respectively. In conclusion, the RF model was superior to the LR model for survival prediction in the rat model.