• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.5
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• pp.610-614
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• 2012

This study was done to identify correlates of carotid artery ultrasonography's measurement and Inyoung pulse in college students. We measured the amplitude of Inyoung pulse, Chongu pulse, ratio of Inyoung to Chongu and ratio of Chongu to Inyoung on 30 college students. Also, We measured the Distance, Diameter), RI(resistivity index), S/D(systolic, diastolic ratio), PI(pulsatility index), PSV(peak systolic velocity), EDV(End diastolic velocity), Vmean using carotid artery ultrasonography. The data was analyzed by Pearson's correlation coefficient using SAS program. The results were as follow. Results showed a positive correlation between Inyoung pulse and diameter by carotid artery. It showed a positive correlation between Inyoung pulse and S/D. Also, It showed a positive correlation between Inyoung pulse and PSV. As a result, the strength of Inyoung pulse related with the diameter of carotid artery and blood flow velocity.

• Biomedical Science Letters
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• v.13 no.3
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• pp.231-237
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• 2007

Subway environments such as crowd, passenger's gab, or subway-generated mechanical noise may become a potential stressor. The present study was sought to determine whether subway noise with or without mental activity affects cerebral hemodynamics and sympathetic system. Fifty-four healthy volunteers were divided group I which underwent subway noise (n=24) and group II which underwent a combined mental activity (mental arithmetic) with subway noise (n=30). Sympathetic factors such as heart rate (HR), blood pressure (BP) and heart rate-systolic pressure product (RPP), and mean blood flow velocity in the middle cerebral artery (MCAV) were measured before (baseline), during and after the noise-exposure. Systolic and diastolic blood pressure, HR and RPP significantly increased in group II (P<0.05) but not in group I during the noise-exposure. Peak-MCAV, diastolic-MCAV and mean-MCAV in the both groups were elevated during the noise-exposure (P<0.05) and the increased ratios in group II were greater than those in group I. These results suggest that a combined mental activity with subway noise may be a stressor which affects cerebral hemodynamics and sympathetic system.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.552-557
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• 2007

Due to the recent improvement of living standard of residential buildings, the requirements of the thermal comfort and energy saving in heating system have been raised. The radiant floor heating system has been widely used as a residential heating method, which has been modernized to use hot water running into the tubes embedded in the floor structure. The uniform flow distribution is very important factor for a radiant floor heating system such as a blood vessel system in human body. Therefore, it is necessary to investigate the operating characteristics to develop an optimal radiant floor heating system. In this study, numerical analyses were carried out, using a commercial CFD code, FLUENT, to obtain the velocity distribution under steady, three-dimensional, standard k-$\varepsilon$ model and no-slip condition. Results are graphically depicted with various parameters.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.157-167
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• 1998

Background and Purpose : Cerebrovascular reactivity(CVR) can be estimated by measuring the change of cerebral blood flow that occurs during vasostimulation. To estimate the cerebrovascular reactivity, we investigated the change of flow velocity of the middle cerebral artery(MCA) during hyperventilation and hypoventilation with the transcranial doppler. So we studied whether the CVR measured by this method could show a significant difference between the normal and the cerebral infarction subjects and whether the CVR may decrease with age in normal subjects. Methods : Using transcranial doppler, we measured the mean velocity(Vm), the pulsatility index(P.I.) at the resting state, the end of breath-holding and the end of hyperventilation in 36 normal and 10 cerebral infarction subjects, so we calculated the percentile change of mean velocity(%${\Delta}$Vm) and P.I.(%${\Delta}$P.I.) after the vasostimulation. We estimated the change of Vm, P.I., %${\Delta}$Vm and %${\Delta}$P.I. by the age group and compared those parameters between the age-matched normal control and cerebral infarction subjects. Results : The Vm in MCA significantly decreased with age(p<0.05), but there was no significant difference in Vm and P.I. between normal and cerebral infarction subjects. The %${\Delta}$Vm and %${\Delta}$P.I. in response to hyperventilation significantly decreased with age in MCA and there was significant difference in $%{\Delta}Vm$ of MCA after breath-holding between the normal and cerebral infarction subjects. Conclusion : The breath-holding and hyperventilation tests could be non-invasive and useful methods in estimation of the cerebrovascular reactivity and could be applied in the basal and follow-up evaluation of the cerebrovascular reserve of the ischemic stroke patients.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.362-370
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• 2019

This study was conducted to investigate effects of 12 weeks of combined exercise training with blood flow restriction (BFR) on body composition (weight, %body fat, lean body mass, body mass index (BMI)) and cardiovascular responses (brachial-ankle pulse wave velocity (ba PWV) and ankle-brachial index (ABI)) in elderly women. Participants (N = 43, Females) were randomly assigned into a combined exercise with BFR (n = 14, BFR), only combined exercise (n =14, EX) or non-exercise control group (n = 15, CON). Two-way repeated measures ANOVA with contrast testing was utilized for data analysis. Alpha was set at p < 0.05. Body composition (weight, %body fat, BMI) in BFR was significantly changed, and %body fat in EX was significantly decreased, but there was no change in the CON. In addition, the right and left ba PWV values in the BFR were significantly decreased, while only the left side ba PWV in EX was significantly decreased and there was no change in the CON. Moreover, the % change and effect size of most variables in the BFR were higher than the EX. Taken together, the results indicate that even though BFR and EX groups performed the same combined exercise training, BFR had additional stimulations of the sympathetic nerve system due to blood flow restriction. Thus, BFR training is more beneficial and has greater effects on body composition and cardiovascular responses in elderly females.

• Journal of Medicine and Life Science
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• v.20 no.3
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• pp.115-125
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• 2023

Arteriovenous fistula flow dysfunction is the leading cause of vascular access thrombosis and loss in patients undergoing hemodialysis. However, data regarding the influence of access flow rate measurements on the long-term outcomes of access are limited. This study aims to identify accesses at a high risk of thrombosis and loss among patients undergoing hemodialysis by measuring the access flow rate and exploring an optimal threshold value for predicting future access thrombosis. We enrolled 220 patients with arteriovenous fistula undergoing hemodialysis. The primary outcome was the occurrence of access thrombosis. Access flow rates were measured monthly using the ultrasound dilution method and were averaged using all measurements from patients with patent access. In patients experienced access thrombosis, those immediately before the thrombosis were selected. Using these data, we calculated the access flow rate threshold for thrombosis occurrence by analyzing the receiver operating characteristic curve, and the patients were divided into two groups according to whether access flow rates were higher or lower than 400 mL/min. During a median follow-up period of 3.1 years, 4,510 access flows were measured (median measurements per patient, 33 times; interquartile range, 11-54). A total of 65 access thromboses and 19 abandonments were observed. Access thrombosis and loss were higher in the lowflow group than in the high-flow group. This study revealed that low access flow rates are strongly associated with access thrombosis occurrence and subsequent loss of arteriovenous fistulas in patients undergoing hemodialysis.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.123-130
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• 2007

Hypoplastic left heart syndrome is currently the most lethal cardiac malformation of the newborn infant. Survival following a Norwood operation depends on the balance between systemic and pulmonary blood flow, which is highly dependent on the fluid dynamics through the interposition shunt between the two circulations. The purpose of this study is an optimization of the systemic-to-pulmonary artery shunt. In this study, We used computational fluid dynamic(CFD) models to determine the velocity profile in a systemic-to-pulmonary artery shunt and suggested a simplified method of calculating the blood flow in the shunt based on Ultrasound systems. We analyzed the flow characteristic variations and oscillatory shear index(OSI) due to the anastomosis angle and shunt diameter changing. Four different CFD models were constructed with the shunt sizes ranging from 3 to 3.5mm. The angle between the brachiocephalic trunk(BCT) and the shunt were $30^{\circ}$ and $45^{\circ}$, respectively. When the diameter is 3.0 mm, the oscillatory shear index decreased by 1.2% at $30^{\circ}$ as opposed to at $45^{\circ}$. When the diameter is 3.5 mm, it increased by 18% more at $30^{\circ}$ as opposed to at $45^{\circ}$. When the joint angle is $30^{\circ}$ and the diameter is 3.0 mm, the oscillatory shear index decreased by 4.1% in comparison with the 3.5 mm diameter. When the angle is $45^{\circ}$ and the diameter is 3.0 mm, the index increased by 14.6% in comparison with the 3.5 mm diameter.

• Korean Journal of Clinical Laboratory Science
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• v.55 no.3
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• pp.219-226
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• 2023

Transcranial doppler ultrasonography (TCD) applies a low frequency of 2 MHz to measure the blood flow velocity and waveform within the skull. Medical technologists at several hospitals are conducting these examinations, and education is being imparted in many schools and academic societies. However, the skill of the tester is of utmost importance when performing TCD. Technicians who are conducting the procedure for the first time have trouble locating the blood vessels, and some experienced personnel are worried because too many blood vessels are present. Since this procedure does not directly look at and measure blood vessels, there are several limitations and difficulties. Therefore, this study aims to provide some help by introducing precautions and suggestions for TCD technicians conducting the test.

• Journal of Korean Neurosurgical Society
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• v.39 no.1
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• pp.20-25
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• 2006

Objective : The authors analyze prospectively the result of transcranial doppler[TCD] in normal pressure hydrocephalus and compared its cerebral blood flow parameters to radionuclide cerebrospinal fluid[CSF] flow study, postoperative brain computed tomography[CT] findings and clinical outcome, and studied the relationship between cerebral hemodynamics and clinical performance. Methods : Twenty five patients with hydrocephalus undertook pre- and post-operative TCD but only preoperative CSF flow study was performed. Mean flow velocity[Vm], pulsatility index[PI] and resistance index[RI] were assessed through TCD and changes in ventricle size and cortical gyral atrophy were checked through brain CT. Results : Postoperative hydrocephalus showed an increase in Vm[ACA P=0.037, MCA P=0.034], decrease in PI[ACA P=0.019, MCA P=0.017] and decrease in RI [ACA P=0.017, MCA P=0.021] compared to preoperative TCD parameters in the postoperative improvement group. In the postoperative improvement group, postoperative TCD parameters correlated with CSF flow study grade [Vm : $R^2=-0.75$, PI : $R^2=0.86$, RI : $R^2=0.78$] and ventriculocranial ratio change correlated with PI change [$R^2=0.73$]. The convexity gyral atrophy and initial TCD parameters showed close relationship to outcome. Conclusion : PI and RI can be used as an indicator of post operative prognosis, and with the addition of CSF flow study values, can also be used as a tool to predict pre-op and post-op patient status and successful shunt surgery.

• The Korean Journal of Physiology
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• v.6 no.2
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• pp.39-48
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• 1972

Two polyethylene tubes were inserted into the esophagus of anesthetized rabbit in order to record the fluctuation of the intraluminal pressure through the orifices located near the tips of the tubes. The orifice of the first tube was 10 cm apart from the incisor of the rabbit and the orifice of the second tube was 5 cm below that of the first one. The tubes were filled with saline solution running at various rates ranging from 1.5 ml/min. to 4.2 ml/min. The tubes were connected to the pressure transducers and the electrical signals were recorded by the physiograph. When the peristaltic wave approached to the orifice a rise in the pressure was recorded, returning to the base line when the portion of the orifice was quiescent. The frequency of the peristaltic motion and the velocity of the wave were studied in connection with the flow rate of saline solution through the tubes and in the case of massive acute hemorrhage. The results obtained were as follows: 1. There was reflux of fluid induced during the procedure of the experiment. This outwrad flow through the pharynx seemed to elicite swallowing reflexes. Accordingly, the frequency of peristalsis of the esophagus was largely dependent on the flow rate of the fluid through the inserted tubes. By the flow rate of 1.5 ml/min., 2.5 ml/min., or 4.2 ml/min., the frequencies of the peristalsis were revealed to be $8.6{\pm}3.6/10min.,\;14.5{\pm}4.8/10min.\;or\;21.1{\pm}6.3/10min.,$ respectively. The velocity of peristalsis also coincided with the enhanced motility of the esophagus, showing $6.6{\pm}1.5\;cm/sec.,\;8.9{\pm}3.9\;cm/sec.,\;or\;12.4{\pm}4.6\;cm/sec.,$ respectively. 2. By acute hemorrhage, amounting to 2% of the body weight, the frequency of the peristalsis increased to twofold of the control and the propagation velocity also increased by 52 percent. 3. Retransfusion of the shed blood resulted in divergent responses. In some cases there were noticable ameliorations of the effects brought by acute hemorrhage, and in the others there were still increasing tendenies of the motility after the transfusion. 4. Some speculation was made about the possibility of a kind of relationship between the irreversibility of the hemorrhagic shock and the absence of responses by transfusion. 5. The peristalsis persisted even after complete disconnection at the midportion of the esophagus, reaffirming the view of a central regulation of the spatiotemporally coordinated motility, peristalsis.