• 대한의생명과학회지
• /
• 제11권4호
• /
• pp.435-439
• /
• 2005

To determine the appropriate concentration of papaverine hydrochloride(PPV) for therapeutic intraarterial infusion against cerebral vasospasm and to measure the mean blood flow velocity of the middle cerebral artery in rabbits. Vasospasm was induced in the experimental groups (3 days after infusion; group 1, n=3, 7 days after infusion; group 2, n=3) and a control group (n=l) by placing a blood clot in the subarachnoid space around the top of the internal carotid siphon. PPV (5 mg/kg) was infused into the internal carotid artery. The vascular diameters of the internal carotid artery (ICA) and middle cerebral artery (MCA) were measured on angiograms before and after infusion. The mean blood flow velocity in the MCA was measured on transcranial doppler sonograms before and 24 hours after infusion. After fixation, the MCA was dissected out, stained, and examined microscopically. After PPV infusion in both groups, vascular dilatation of about $20\%$ was seen. The mean increase in blood flow velocity in the group $1(30\%)$ was smaller than in the group $2(70\%)$. The mean blood flow velocity in the MCA decreased by about $30\%$ in both groups, but increased again after 24 hours nearly to the level before PPV infusion. PPV infusion may be more effective in early stages of vasospasm when vascular walls have fewer histologic changes.

• 한국임상수의학회지
• /
• 제19권3호
• /
• pp.277-282
• /
• 2002

본 실험은 각각의 마취방법이 체성감각유발전위 (SEPs) 파형에 미치는 영향을 알아보고 SEP의 측정에 적절한 마취방법을 찾고자 시행하였다. 임상적으로 건강하고 크기와 나이가 비슷한 다섯 마리의 잡종견을 대상으로 SEPs를 측정하고 각각의 측정값을 분석하였다. SEPs측정을 위해 후 경골신경을 자극하였고 요추 5-6번 사이에서 channel 1의 LP1과 LN1, 흉추 11-12사이에서 channel 2의 TP1, TN1을 기록하였다. 실험에 사용한 마취방법 중. Acepromazine + Thiopental Na + Isoflurane, Acepromazine + Propofol + Isoflurane, Diazepam + Xylazine, Xylazine + Ketamine, Acepromazine + Propofol infusion, 및 Propofol infusion등의 방법만이 SEPs측정이 가능하였고, 파형은 명확하였으며, 측정에 요구되어지는 일정 시간인 25분 이상 동안 마취 유지가 가능하였다. 또한 각 마취군에서의 SEPs 파형을 Acepromazine + Thiopental Na + Isoflurane군과 비교해 보았을 때 latency의 경우, Acepromazine + Propofol + Isoflurane군의 ST(stimulating point)-LN1, SP-TP1, Diazepam + Xylazine 군의 Chl-Ch2, Xylazine + Ketamine군의 Chl-Ch2, Acepromazine + Propofol infusion군의 ST-LP1와 Chl-Ch2에서 부분적으로 유의적인 차가 있었다. Conduction velocity의 경우, Acepromazine + Propofol + Isoflurane군의 ST-LN1, Diazepam + Xylazine군의 Chl-Ch2, Xylazine + Ketamine군의 Chl-Ch2, Acepromazine + Propofol infusion군의 ST-LP1, 그리고 Propofol infusion군의 ST-LN1의 측정값에서 유의적인 차가 있었지만 전반적으로는 전체적인 파형의 유의적인 변화는 없었다. 이상의 결과를 토대로 SEPs 측정시 흡입마취로는 Acepromazine + Thiopental + Isoflurane과 Acepromazine + Propofol + Isoflurane, 주사마취로는 Diazepam + Xylazine과 Xylazine + Ketamine, 점적마취로는 Acepromazine + Propofol infusion과 Propofol infusion 방법이 사용 가능한 것으로 확인되었다.

• Annals of Clinical Neurophysiology
• /
• 제1권1호
• /
• pp.64-69
• /
• 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.

• 대한의용생체공학회:의공학회지
• /
• 제26권3호
• /
• pp.157-161
• /
• 2005

Direct injection of a fibrinolytic agent to the intraarterial thrombosis may increase the effectiveness of thrombolysis by enhancing the permeation of thrombolytic agents into the blood clot. Permeation of fibrinolytic agents into a clot is influenced by the surface pressure, which is determined by the injection velocity of fibrinolytic agents. In order to calculate the pressure distribution on the clot surface for different jet velocities (1, 3, 5 m/sec) and nozzle arrangements (1, 9, 17 nozzles), computational fluid dynamic methods were used. Thrombolysis of a clot was mathematically modeled based on the pressure and lysis front velocity relationship. Direct injection of a thrombolytic agent increased the speed of thrombolysis significantly and the effectiveness was increased as the ejecting velocity increased. The nine nozzles model showed about $20\%$ increase of the lysed volume, and the one and seventeen nozzles models did not show significant differences. The wall shear stress decreased as the number of nozzles increased, and the wall shear stress in most vessel wall was lower than 25 Pa. The results implied that thrombolysis could be accelerated by direct injection of a drug with the moderate velocity without damaging the blood vessel wall.

• Annals of Clinical Neurophysiology
• /
• 제1권1호
• /
• pp.55-59
• /
• 1999

Vasoconstriction of intracerebral arteries is the leading cause of delayed cerebral infarction and mortality following aneurysmal subarachnoid hemorrhage. Transcranial Doppler studies show and increase in the flow velocities of basal cerebral arteries, which usually start around day 4 following a subarachnoid hemorrhage, and peaking by days 7 to 14. Angiographic studies confirm the presence of at least some degree of MCA vasospasm when the flow velocities are higher than 100 cm/sec. Mean velocities in the 120 to 200 cm/sec range correspond to 25 to 50% luminal narrowing. MCA and ACA vsospasm is detected with around 90% specificity. Sensitivity is 80% and 50% respectively. A 200cm/sec threshold and rapid flow velocity increase exceeding 50 cm/sec on consecutive days, has been associated with subsequent infarction. Transcranial Doppler is also used to monitor the effects of endovascular treatment of vasospasm. Flow velocities decrease following successful angioplasty or papaverine infusion. Overall, transcranial Doppler studies are considered to have acceptable accuracy for the evaluation of vasospasm in aneurysmal subarachnoid hemorrhage, with limitations that have to be taken into consideration in the clinical setting.

• Tribology and Lubricants
• /
• 제15권3호
• /
• pp.278-286
• /
• 1999

To predict the behavior of the intravascular micro active endoscope in the real human vascular system, a human mock circulation system was developed. The intravascular micro active endoscope which consists of micro active bending catheter and micro drug infusion catheter was driven in the velocity, Re number and temperature controlled flow. The three SMA (Shape Memory Alloy) zigzag type spring in the micro active bending catheter was heated by the electric current generated by PWM controller, and the shape memory effect made the actuator bend to any direction. The micro drug infusion catheter was driven through the inner hole of the micro active bending catheter. A mock circulation system is shaped from Ascending Arota to Femoral artery according to a human data (the data contains many vascular sizes and hydrographs of many control points). We developed a vascular model with glass and silicone tubes, and set the flow system with circulation parts, flow settling parts, and lots of valves. The heater and heat-controller was added to the How system to centre! the temperature of the How at 36.5$^{\circ}C$. The result showed that the developed intravascular micro active endoscope could be induced to any point in the vascular model.

• Journal of Korean Neurosurgical Society
• /
• 제46권3호
• /
• pp.239-244
• /
• 2009

Objective : Cerebral vasospasm leading to cerebral ischemic infarction is a major cause of morbidity and mortality in the patients who suffer with aneurysmal subarachnoid hemorrhage. Despite adequate treatment, some patients deteriorate and they develop symptomatic vasospasm. The objective of the present study was to investigate the efficacy and clinical outcome of intraarterial nimodipine infusion on symptomatic vasospasm that is refractory to hemodynamic therapy. Methods : We retrospectively reviewed the procedure reports, the clinical charts and the transcranial doppler, computed tomography and digital subtraction angiography results for the patients who underwent endovascular treatment for symptomatic cerebral vasospasm due to aneurysmal SAH. During the 36 months between Jan. 2005 and Dec. 2007, 19 patients were identified who had undergone a total of 53 procedures. We assessed the difference in the arterial vessel diameter, the blood flow velocity and the clinical outcome before and after these procedures. Results : Vascular dilatation was observed in 42 of 53 procedures. The velocities of the affected vessels before and after procedures were available in 33 of 53 procedures. Twenty-nine procedures exhibited a mean decrease of 84.1 cm/s. We observed clinical improvement and an improved level of consciousness with an improved GCS score after 23 procedures. Conclusion : Based on our results, the use of intraarterial nimodipine is effective and safe in selected cases of vasospasm following aneurysmal SAH. Prospective, randomized studies are needed to confirm these results.

• 대한의용생체공학회:의공학회지
• /
• 제27권5호
• /
• pp.267-273
• /
• 2006

Numerical analysis was performed on the enzyme transport and the flow fields in order to predict the effectiveness of urokinase injection regimens in clot dissolution. The species and momentum transport equations were numerically solved for the case of uniform perfusion of enzyme into a fibrin clot for an arterial thrombus and a deep vein thrombus models. In order to predict the thrombus lysis efficiency of continuous and forced intermittent injections, enzyme perfusion and clot lysis were simulated for the different injection velocities. Intermittent injection showed faster clot lysis compared to continuous perfusion, and lysis efficiency was increased as injection velocity increased.

• Steel and Composite Structures
• /
• 제48권3호
• /
• pp.305-320
• /
• 2023

The mechanical properties of polymeric composites are degraded under elevated temperatures due to the effect of temperature on the mechanical behavior of the resin and resin fiber interfaces. In this study, the effect of temperature on the impact response of the carbon fiber reinforced plastics (CFRP) was investigated at low-velocity impact (LVI) using a drop-weight impact tester machine. All the composite plates were fabricated using a vacuum infusion process with a stacking sequence of [45/0_2/-45/90_2]s, and a thickness of 2.9 mm. A group of the specimens was exposed to an environment with a temperature cycling at the range of -30 ℃ to 65 ℃. In addition, three other groups of the specimens were aged at ambient (28 ℃), -30 ℃, and 65 ℃ for ten days. Then all the conditioned specimens were subjected to LVI at three energy levels of 10, 15, and 20 J. To assess the behavior of the damaged composite plates, the force-time, force-displacement, and energy-time diagrams were analyzed at all temperatures. Finally, radiography, optical microscopy, and scanning electron microscopy (SEM) were used to evaluate the effect of the temperature and damages at various impact levels. Based on the results, different energy levels have a similar effect on the LVI behavior of the samples at various temperatures. Delamination, matrix cracking, and fiber failure were the main damage modes. Compared to the samples tested at room temperature, the reduction of temperature to -30 ℃ enhanced the maximum impact force and flexural stiffness while decreasing the absorbed energy and the failure surface area. The temperature increasing to 65 ℃ increased the maximum impact force and flexural stiffness while decreasing the absorbed energy and the failure surface area. Applying 200 thermal cycles at the range of -30 ℃ to 65 ℃ led to the formation of fine cracks in the matrix while decreasing the absorbed energy. The maximum contact force is recorded under cyclic temperature as 5.95, 6.51 and 7.14 kN, under impact energy of 10, 15 and 20 J, respectively. As well as, the minimum contact force belongs to the room temperature condition and is reported as 3.93, 4.94 and 5.71 kN, under impact energy of 10, 15 and 20 J, respectively.

• Clinical and Experimental Pediatrics
• /
• 제49권12호
• /
• pp.1275-1281
• /
• 2006

목 적 : 뇌수막염은 뇌와 척수를 둘러싸는 막의 염증으로 여름과 가을에 소아들에 호발하여 합병증이 발생하면 신경학적 후유증을 야기할 수 있는 질환이다. 뇌수막염의 합병증으로 뇌부종이 발생한 경우 증상치료로서 mannitol과 고장성 식염수가 삼투성 이뇨치료로 이용되어진다. 고장성 식염수는 다양한 농도와 투여방법이 있을 수 있는데 본 연구는 고장성 식염수의 가장 효과적이고 안전한 투여 형태에 대해 고찰하였다. 방 법 : 2002년 1월부터 2005년 10월까지 부산의료원 소아과에 입원하였던 뇌수막염환아 283명중 뇌부종이 발생했던 42명의 환아를 대상으로 하였다. 20% mannitol과 4가지 형태의 고장성 식염수로 치료하였던 5가지 투여군을 분석하였다. 증상과 징후의 호전유무, 뇌압측정치, 뇌혈류속도 측정치, 검사소견으로 효과적인 투여형태에 대해 통계적 분석을 하였다. 결 과 : 1) 환아의 평균연령은 5.34세이었으며 남녀 비율은 남아가 22명이고 여아는 20명이었다. 주된 임상양상은 발열(97%), 두통(92%), 구토(71%), 경련(47%), 기면(35%), 경부강직(35%), 복통(35%), 기침(35%), 유두부종(35%), 보챔(28%), 수두증(11%) 순으로 나타났다. 2) 증상 및 징후의 호전유무는 치료 4일째 24명이 상기증상 및 징후의 50%이상의 호전을 나타내었다. 3% 고장성 식염수 농축괴와 3% 고장성 식염수 연속적 농축괴 그리고 7.5% 고장성 식염수 연속적 농축괴의 방법이 효과적인 것으로 분석되었다(P<0.05). 3) 뇌압측정치는 5가지 방법모두 뇌압하강효과가 있는 것으로 나타났다. 3% 고장성 식염수 연속적 농축괴 주입이 뇌압하강치가 1.86 kPa로서 가장 좋은 기록이었지만 통계학적 의미는 없었다(P=0.31). 4) Transcranial doppler에 의한 MFV와 PI 측정에서는 5가지 방법 모두 MFV도의 상승과 PI 하강을 보여주었다. PI와 MFV 상에서는 5가지 방법에서 치료효과의 차이가 없는 것으로 분석할 수 있었다(P=0.59, P=0.99). 5) 치료기간동안 다양한 검사소견을 비교할 수 있는데 나트륨, 염소, 수소이온농도, 젖산, 몰삼투압농도, 칼슘은 차이가 날 수 있는 것으로 관찰되었고(P<0.05), 칼륨, 혈색소, 중탄산염, 염기 과다는 차이가 없는 것으로 분석되었다. 나트륨, 염소, 몰 삼투압농도는 약간 상승되었고 수소이온농도, 젖산, 칼슘은 약간 하강하였으나 큰 변화는 없었다. 결 론 : 뇌수막염에서 뇌압상승, 뇌부종이 발생한 환아의 증상치료로서 고장성 식염수가 다양한 농도와 투입방법이 고려되어 질 수 있다. 본 연구의 결과로는 3% 고장성 식염수 연속적 농축괴의 투여방법이 가장 우수해 보이나 무작위 추출이 아니며 여러 가지 결과를 종합할 때 가장 우수하다고 하기에는 무리가 있었다. 향후 보다 더 많은 집단을 대상으로 한 무작위 추출의 다양하고 종합적인 연구가 필요할 것으로 사료된다.