• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.2
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• pp.71-84
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• 2015

A low-profile flow sensor has been designed, fabricated, and characterized to demonstrate the feasibility for monitoring hemodynamics in cerebral aneurysm. The prototype device is composed of three micro-membranes ($500-{\mu}m$-thick polyurethane film with $6-{\mu}m$-thick layers of nitinol above and below). A novel super-hydrophilic surface treatment offers excellent hemocompatibility for the thin nitinol electrode. A computational study of the deformable mechanics optimizes the design of the flow sensor and the analysis of computational fluid dynamics estimates the flow and pressure profiles within the simulated aneurysm sac. Experimental studies demonstrate the feasibility of the device to monitor intra-aneurysmal hemodynamics in a blood vessel. The mechanical compression test shows the linear relationship between the applied force and the measured capacitance change. Analytical calculation of the resonant frequency shift due to the compression force agrees well with the experimental results. The results have the potential to address important unmet needs in wireless monitoring of intra-aneurysm hemodynamic quiescence.

• Annals of Clinical Neurophysiology
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• v.1 no.1
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• pp.64-69
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• 1999

Background : Syncope was defined as transient loss of consciousness and postural tone. The mechanisms of changes in cerebral hemodynamics during syncope have not been fully evaluated. Transcranial Doppler Ultrasonography can continuously monitor the changes in cerebral hemodynamics during head-up tilt (HUT). TCD could reveal the different patterns of changes in cerebral hemodynamics during syncope. Syncope without hypotension or bradycardia could be detected by TCD. We investigated the changes in cerebral blood flow velocity during HUT using TCD in 33 patients with a history of recurrent syncope or presyncope of unknown origin. Methods & Results : The positive responses were defined as presyncope or syncope with hypotension, bradycardia, or both. During HUT without isoproterenol infusion, there were a $86{\pm}23%$ drop in DV and a $41{\pm}34%$ drop in SV in 5 patients with positive reponses, and mean changes in those were less than 10% in patients with negative reponses (p=.00, p=.00). During HUT with isoproterenol infusion, TCD showed a $80{\pm}18%$ drop in diastolic velocity in 14 patients with positive reponses, and a $47{\pm}10%$ drop in that in patients with negative reponses (p=.00), however the change in systolic velocity did not differ. TCD showed three patterns during positive responses; loss of all flow, loss of end diastolic flow, and a decrease in diastolic velocity. Loss of consciousness occurred in the patients with loss of all flow or end-diastolic flow during positive reponses. Conclusions : TCD shows different patterns of changes in cerebral hemodynamics during HUT. TCD can be used to investigate the pathophysiology of neurocardiogenic syncope.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.382-392
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• 2023

Objective : The use of indocyanine green videoangiography (ICG-VA) to assess blood flow in the brain during cerebrovascular surgery has been increasing. Clinical studies on ICG-VA have predominantly focused on qualitative analysis. However, quantitative analysis numerical modelling for time profiling enables a more accurate evaluation of blood flow kinetics. In this study, we established a multiple exponential modified Gaussian (multi-EMG) model for quantitative ICG-VA to understand accurately the status of cerebral hemodynamics. Methods : We obtained clinical data of cerebral blood flow acquired the quantitative analysis ICG-VA during cerebrovascular surgery. Varied asymmetric peak functions were compared to find the most matching function form with clinical data by using a nonlinear regression algorithm. To verify the result of the nonlinear regression, the mode function was applied to various types of data. Results : The proposed multi-EMG model is well fitted to the clinical data. Because the primary parameters-growth and decay rates, and peak center and heights-of the model are characteristics of model function, they provide accurate reference values for assessing cerebral hemodynamics in various conditions. In addition, the primary parameters can be estimated on the curves with partially missed data. The accuracy of the model estimation was verified by a repeated curve fitting method using manipulation of missing data. Conclusion : The multi-EMG model can possibly serve as a universal model for cerebral hemodynamics in a comparison with other asymmetric peak functions. According to the results, the model can be helpful for clinical research assessment of cerebrovascular hemodynamics in a clinical setting.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.3
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• pp.231-233
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• 2017

Wolf-Hirschhorn syndrome is a rare hereditary disease that results from a 4p chromosome deletion. Patients with this syndrome are characterized by craniofacial dysgenesis, seizures, growth delay, intellectual disability, and congenital heart disease. Although several cases have been reported, very little information is available on anesthetic management for patients with Wolf-Hirschhorn syndrome. We encountered a case requiring anesthetic management for a 2-year-old girl with Wolf-Hirschhorn syndrome. The selection of an appropriately sized tracheal tube and maintaining intraoperatively stable hemodynamics might be critical problems for anesthetic management. In patients with short stature, the tracheal tube size may differ from what may be predicted based on age. The appropriate size ( internal diameter ) of tracheal tubes for children has been investigated. Congenital heart disease is frequently associated with Wolf-Hirschhorn syndrome. Depending on the degree and type of heart disease, careful monitoring of hemodynamics is important.

• The Journal of Internal Korean Medicine
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• v.22 no.2
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• pp.199-205
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• 2001

Background and Purpose : Transcranial doppler ultrasonography(TCD) is a noninvasive and nonradioactive technique for evaluation of the hemodynamics in large cerebral vessels. Sahyangsohap-won(SS) has been considered to be effective for the treatment of various disease, especially cerebrovascular, cardiovascular, and psychosomatoform disorders. But, there is no study about the effect of SS on the cerebral hemodynamics in humans. The aim of this study was to assess the effect of SS on the changes in cerebral hemodynamics and the dose-dependant effect by using TCD. Subjects and Methods : 30 healthy subjects were randomly divided into three group: group 1 took no drug, group 2 took SS one pill, and group 3 took SS 2 pills. Changes in the mean blood flow velocity(MBFV) and pulsatility index(PI) in the middle cerebral artery were evaluated by means of TCD. We obtained hypercapnia with breath-holding and evaluated cerebrovascular reactivity with the breath-holding index(BHI). Systolic blood pressure(SBP), diastolic blood pressure(DBP), and heart rate(HR) were measured by means of ambulatory blood pressure monitoring. In group 2 and group 3, the evaluations were performed during the baseline and were repeated at 20, 40, and 60 minutes after SS administration. In group 1, the evaluation was performed at corresponding time intervals. Results : In mean values of MSFV, PI, SSP, DBP, and HR, no stastically significant differences were found between the 3 groups. However, BHI values were significantly lower in groups 2 and 3 than in group 1 at 40 minutes after SS administration(P<0.05, group 1 vs group 2, group 1 vs group 3 by post-hoc analysis: Scheffe's test) but in dose-dependant effect, there was no difference between group 2 and group 3. Conclusion : These results suggest that SS can decrease vascular resistance in cerebral small arteries or arterioles and enhance their distensibility. Further studies on larger numbers of subjects are needed to confirm these effects and the dose-dependant effects.

• Current Optics and Photonics
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• v.4 no.1
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• pp.57-62
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• 2020

The selection of anesthetic agent is important in preclinical studies, since each agent affects the systemic hemodynamics in different ways. For that reason, we hypothesized that different anesthetic agents will result in different vaginal hemodynamic response and temperature during sexual arousal, in an animal model. To validate the hypothesis, animal experiments were performed using female rats with two anesthetic agents widely used in preclinical studies: ketamine and isoflurane. Our previously developed near-infrared-spectroscopy-based probe was used to measure the changes of oxyhemoglobin (OHb), deoxyhemoglobin (RHb), and total hemoglobin (THb) concentrations along with temperature from the animal vaginal wall. As a control, saline was administered to both isoflurane- and ketamine-anesthetized animals, and did not show any significant changes in OHb, RHb, THb, or temperature. However, an administration of apomorphine (APO, 80 ㎍/kg) induced increases of OHb (63 ± 28 μM/DPF), RHb (35 ± 20 μM/DPF), and THb (98 ± 49 μM/DPF) in ketamine-anesthetized animals, while decreases of OHb (52 ± 76 μM/DPF) and THb (38 ± 30 μM/DPF) and an increase of RHb (28 ± 51 μM/DPF) were found in isoflurane-anesthetized animals. The vaginal temperature decreased from the baseline in both ketamine-(0.42℃) and isoflurane-(1.22℃)anesthetized animals. These results confirmed our hypothesis, and suggest that a preclinical study monitoring hemodynamic responses under anesthesia should employ an appropriate anesthetic agent for the study.

• Clinical and Experimental Pediatrics
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• v.48 no.6
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• pp.649-654
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• 2005

Purpose : The present study examined how changes in cerebral hemodynamics in newborn piglets with bilirubin infusion can be evaluated by near infrared sepctroscopy(NIRS). Methods : Seventeen newborn piglets were randomly divided into the following three experimental groups : six in the control group(CG); seven in the bilirubin infusion group(BG), and four in the bilirubin infusion with 7-nitroindazole group(NG). To achieve the concentration of bilirubin above 20 mg/dL, we injected a bolus of 40 mg/kg of bilirubin intravenously, followed by 30 mg/kg/hr of bilirubin continuous intravenous infusion. All groups were monitored with cerebral hemodynamics using near infrared spectroscopy(NIRS) and their brain cortexes were harvested and the activities of $Na^+$, $K^+$-ATPase, level of conjugated dienes, ATP and phosphocreatine(PCr) were determined biochemically. Results : No changes took place in CG. In BG and NG, base excess, pH, and MABP decreased, and lactate level in blood increased. Cerebral $Na^+$, $K^+$-ATPase activity and ATP, PCr level in BG significantly decreased and conjugated dienes increased compared to CG. These abnormalities observed in the BG were significantly improved in the NG. In continuous NIRS monitoring, [$HbO_2$], [HbT], and [HbD] in BG were significantlly decreased compared to CG. However these abnormalities between NG and CG were not significantly different. There were no significant differences in $ScO_2$ between the study groups. Conclusion : Our study suggests cerebral hemodynamic changes could be monitored by non-invasive NIRS in newborn piglets with bilirubin infusion.

• Journal of Chest Surgery
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• v.17 no.1
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• pp.59-66
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• 1984

After open heart surgery, the patient must be carefully observed and adequately managed for his survival. This report reviewed 10 cases of ventricular septal defect and 12 mitral valvular diseases as hemodynamics early after open heart surgery. For postoperative 24 hours, clinical status was evaluated for left atrial pressure, central venous pressure,DP[LAP-CVP], peak systolic pressure, heart rate, urine amount, and other clinical findings. Especially, on postoperative fourth hour, cardiac output was most decreased, when the changes of monitoring were compared with two groups with or without using cardiotonics. Finally, we concluded as followings; 1.Postoperatively, variation of CVP was noted in VSD, but mitral valvular disease was more variable change of LAP. 2.DP was 1.3\ulcorner.4 cmH2O in VSD, and 6.4\ulcorner.2 cmH2O in mitral valvular disease. 3.Parameter using cardiotonic was CVP in VSD, and LAP in mitral valvular disease.

• Annals of Clinical Neurophysiology
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• v.21 no.2
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• pp.71-78
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• 2019

Transcranial Doppler (TCD) was introduced in 1982 to assess intracranial arteries noninvasively, since when it has been widely used to assess and monitor cerebrovascular hemodynamics. The clinical applications of TCD are broadening to include other fields that require monitoring of the cerebral blood flow. TCD has fewer temporal and spatial restrictions than other methods, can be performed on less-compliant patients, and causes no harm to the body. However, its reliance on high levels of examiner skill and experience, as well as a lack of standardized scanning protocols are obstacles that still need to be overcome. In this report we review TCD examination techniques and interpret their findings for several conditions.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.413-419
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• 2001

This study was performed to evaluate the renal hemodynamics using color Doppler ultrasonography in dogs with unilateral experimental hydronephrosis treated with transarterial embolization of the renal artery (TAE-RA). Experimental hydronephrosis was induced by ligation of unilateral ureter in 12 dogs. The mean resistive index (RI) value of kidney was significantly increased at 4, 9, 17 days after ligation of ureter. Unilateral hydronephrosis was established in 12 dogs at 17 days after ligation of ureter. Renal artery embolization was performed using selective catheterization in the hydronephrotic kidney of seven dogs and EKG, $SpO_2$body temperature, pulse, and respiratory rate were within normal ranges during procedures. There were no dogs expired after TAE-RA and no side effects associated with regurgitation of iohexol-ethanol solution. In color Doppler ultrasonographic findings, there was no blood flow into the embolized kidneys treated by TAE-RA, however, blood flow signal was found in contralateral normal kidney of dogs treated with TAE-RA compared to that of normal kidney in normal control group. It is concluded that TAE-RA does not affect the hemodynamics of contralateral normal kidney in dogs with experimental hydronephrosis and color Doppler ultrasonography is simple and non-invasive modality for the monitoring of the revascularization of the renal artery after TAE-RA.