• Journal of the Ergonomics Society of Korea
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• v.29 no.6
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• pp.875-887
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• 2010

The quantitative effectiveness of powered support surfaces such as APAM in preventing and treating pressure ulcers has not been sufficiently evaluated because of uncertainty of alternating pressure load input and lack of interpretation of dynamic perfusion characteristics of soft tissue. The aim was to verify the dynamic loading effects to sacral tissue perfusion characteristics from alternating set pressure changes. We developed integrated experiment system to supply alternating load to supinely positioned sacrum and concurrently measured $TcPO_2$, $TcPCO_2$ and air cell pressure. Ten aged subjects (5 female, 5 male) were tested with alternating set pressure 20, 30, 40, 50 and 60mmHg. From the dynamic perfusion response eight characteristic parameters were proposed such as average, minimum, maximum and perfusion range regarding to $TcPO_2$ and $TcPCO_2$. A one-way ANOVA was carried out to determine whether the manipulation of alternating set pressure had any effect on $TcPO_2$ and $TcPCO_2$. From the dynamic tissue perfusion response we found mean $TcPO_2$ decreased exponentially as alternating pressure load increased and perfusion range varied mainly because of minimum level change of $TcPO_2$. And perfusion range of $TcPCO_2$ affected by increase of maximum value of $TcPCO_2$. From the results we can get more strict insights about actual physiological dynamic tissue perfusion mechanism under alternating pressure load.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.645-646
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• 2006

Pressure-induced decubitus is a serious disease among the elderly people. Interface pressure occluding vascular perfusion is known to be a cause of decubitus. Therefore, it is essential to quantify the relationship between vascular perfusion and interface pressure among the elderly people. Nine elderly normal people ($57.8{\pm}5.6\;years,\;63.3{\pm}7.0kg,\;1.68{\pm}0.05m$) were participated. Pressure was applied on the ischial tuberosity in the sitting posture from 0mmHg to 135mmHg as capillary vascular perfusion was recorded. The average interface pressure to occlude vascular perfusion under the ischial tuberosity is 120mmHg. Vascular perfusion values at the capillary occlusion is often lower than 60% of the vascular perfusion at 15mmHg. Higher sampling number is required to have more accurate results.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.7 s.196
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• pp.126-132
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• 2007

Pressure-induced decubitus is a serious disease among the elderly people. Interface pressure occluding vascular perfusion is known to be a cause of decubitus. Therefore, it is essential to quantify the relationship between vascular perfusion and interface pressure among the elderly people to understand more about decubitus. Nine healthy elderly people (57.8$\pm$ 5.6 years, 63.3$\pm$ 7.0kg, 1.68$\pm$ 0.05m) were participated. Three healthy young people (31.7$\pm$ 3.2 years, 74.7$\pm$ 8.4kg, 1.75$\pm$ 0.04m) were also examined to be compared with the elderly group. Capillary vascular perfusion on the ischial tuberosity was recorded in the sitting posture as pressures were applied from 15mmHg to 135mmHg. The average interface pressure to occlude vascular perfusion (the average occlusion pressure) under the ischial tuberosity was 115.7mmHg in the elderly group. This value was not significantly different from the average occlusion pressure of the young group. Obesity effect on the occlusion pressure was investigated among the elderly group. The result was not significantly different between the obesity and the normal group in this study. This is a preliminary study to unveil the complicated cause of pressure-induced decubitus associated with occlusion of vascular perfusion. More subjects are required for the future study.

• Journal of Chest Surgery
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• v.19 no.1
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• pp.18-24
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• 1986

The mean perfusion pressure produced by 20 different design and size of disposable aortic perfusion cannulas [size range: 18F to 20F] at flow rates of 1 to 5 L/min was compared. A roller pump with perfusion tubing 10mm in inner diameter was used with a mixture of 0.9% normal saline and 100% glycerin [mixing ratio of 6.72:13.28] to make the viscosity as normal blood in 20oC as the test solution. Line pressure in these cannulas at a flow rate of 3L/min ranged from 13.2$\pm$4.47 to 157$\pm$1 34 mmHg in a case of absence of resistance, and from 11.4$\pm$1.14 to 227.2$\pm$4.47 mmHg in a case of presence of resistances 14 cannulas had gradients of less than 100Hg at a flow rate of 3L/min and 9 cannulas less than 100mmHg at 4L/min. The following results were obtained from this experimental study: .1] A wide range of line pressure was observed in disposable aortic perfusion cannulas currently in clinical use; 2] Some cannulas currently used for cardiopulmonary bypass in adults generated excessive line pressure; 3] Both the material and design affect function, with some designs safer than others. Cardiac surgeons should base the choice of aortic perfusion cannula on the best performance and safest design available to avoid cannula-related problems during operation.

• Journal of Chest Surgery
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• v.13 no.4
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• pp.338-345
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• 1980

We have modified an isolated perfusion rat heart model of cardiopulmonary bypass, with which we are able to screen the effects of various cardioplegic solutions and hypothermia upon the ability of the heart to survivie during and recover from period of ischemic arrest. The modified experimental model was differed from the original as follow : a heat coil chamber of atrial and aortic reservoir provided temperature control, and the perfusate was gassed with each pure oxygen and pure carbon dioxide in 95:5 ratio. The Langendorff perfusion was initiated for a 10 minute period by introducing perfusate at $37^{\circ}C.$ into the aorta from the aortic reservoir located 100 cm above the heart. The isolated perfused working rat heart model was a left heart preparation in which oxygenated perfusion medium (at $37^{\circ}C.$) entered the cannulated left atrium at a pressure of 20 cm $H_{2}O$ and was passed to the ventricle, from which it was sponeously elected(no electrical pacing) via an aortic cannula, against a hydrostatic pressure of 100cm $H_{2}O$. during this working period various indices of cardiac functin were measured. The cardiac functions were stable for over 3 hour with perfusion of Krebs-Henseleit bicarbonate buffer solution containing only glucose (11.1 mM/L). The percentage of cardiac functins were maintained about 94% on heart rate, 80.6% on peak aortic pressure, 87.7% on coronary flow and 76.3% on aortic flow rate after 3 hour of working heart perfusion at a pressure of 20 cm $H_{2}O$. We believe this preparation to be a good biochemical model for the human heart which offers many advantages including economic, speed of preparation, reproducibility, and the ability to handle large numbers.

• Neonatal Medicine
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• v.25 no.1
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• pp.1-6
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• 2018

Extremely low birth weight infants remain at increased risk of intraventricular hemorrhage from the fragile vascular bed of the germinal matrix; the roles of hypotension (ischemia) and reperfusion (hyperemia) in the development of intraventricular hemorrhage are still debated. Cerebrovascular pressure autoregulation protects the brain by maintaining constant cerebral blood flow despite changes in blood pressure. The ontogeny of cerebrovascular pressure autoregulation has not been well established and uncertainty remains about the optimal arterial blood pressure required to support brain perfusion. Another important aspect of premature cerebral hemodynamics is the critical closing pressure--the arterial blood pressure at which cerebral blood flow ceases. Interestingly, in premature infants, the critical closing pressure approximates the mean arterial blood pressure. Often in this unique population, cerebral blood flow occurs only during systole when the diastolic arterial blood pressure is equal to the critical closing pressure. Moreover, the diastolic closing margin, a metric of cerebral perfusion that normalizes diastolic arterial blood pressure to the critical closing pressure, may be a better measure than arterial blood pressure for defining cerebral perfusion in premature infants. Elevated diastolic closing margin has been associated with intraventricular hemorrhage. This review summarizes the current state of understanding of cerebral hemodynamics in premature infants.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.967-968
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• 2010

• Journal of Chest Surgery
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• v.21 no.2
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• pp.246-253
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• 1988

An in vitro model providing with a recirculating perfusion apparatus using an isolated canine heart and its autogenous blood, which was prepared for study of myocardial protection method. This apparatus was easily used by quick connect system and maintained well heart function for about 2 hours. The Langendorff perfusion was initiated for a 10 minute period by introducing perfusate at 37` into the aorta from aortic reservoir located 100 cm above the heart. The isolated perfused working canine heart model was a left heart preparation in which oxygenated perfusion medium [at 37K] entered the cannulated left atrium at a constant flow rate [900ml/ min] under 20 mmHg overflow system and was spontaneously ejected[no electrical pacing] via an cannula against a hydrostatic pressure of 80 cm H2O. During this working period, various indices of cardiac function were measured. The cardiac functions were stable for over 2 hours with perfusion of Krebs-Henseleit solution and autologous blood[1:1] mixture in volume and maintained heart rate ]]3-122/bpm peak systolic pressure 109-113 mmHg, cardiac output 900 ml / min and left atrial mean pressure 8-9 mmHg. In this model, the efficiency of myocardia] protection could be easily measured by means of functional, enzymatic, biochemical and ultrastructural assessment. And also, we believe this model to be a useful assessment screening model of recovery state after long duration of myocardial preservation of donor heart without difficult transplantation procedures.

• Journal of Chest Surgery
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• v.4 no.2
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• pp.69-80
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• 1971

Total body perfusion using Rygg-Kyvsgaard Heart-Lung-Machine, Mark IV, Polystan was attempted in the dogs by the hemodilution method with total prime of buffered Hartman's solution and under hypothermia. The first of all, the functions of Rygg--Kyvsgaard Heart-Lung-Machine and the effects of the hemodilution perfusion by buffered Hartman's solution was studied. At the same time the changes of blood pressure, oxygen consumption, and influence on the blood pictures were observed before, during, and in 1-3 days after perfusion. Hemodilution rates were the average 74. 22cc/Kg(the ranges of 67 to 81 cc/Kg) and perfusion flow rates were maintained in the mean 62. 6cc/Kg/min., Although it was possible to check up to 87 cc/ Kg/min. The total body perfusion continued for 60-80 minutes. Hypothermia was employed between $36^{\circ}C$ and $32^{\circ}C$ of the rectal temperature. Arterial pressure was ranged approximately between 68mmHg and 149mmHg, but generally, it was maintained over 80mmHg. Venous pressure was measured between 6.5cm $H_2O$and 11.5cm $H_2O$. Optimum oxygenation can be expected when oxygen flow into the disposable bubble oxygenator was maintained approximately at 3.5 L/min .. Inthis way, the oxygen contents were measured in the mean value of 13.11${\pm}$O.56 vol. % of arterial blood and 8.67+1.08 vol.% of venous blood(P${\pm}$0.86 vol.% in arteriovenous oxygen difference and 2. 97${\pm}$0.62cc/Kg in oxygen consumption were calculated. According to these dates, it is as plain as pikestaff that excellent oxygenation and good tissue perfusion was accomplished. Erythrocyte, hemoglobin and hematocrit were decreased about 38% during extracorporeal circulation and these were not recovered until 1-3 days after perfusion. These decrease was resulted from relatively high degree of hemodilution rate and no blood transfusion to compensate during these experimental studies. The platelets were also decreased about 76% during perfusion, but on the contrary, it was increased progressively after perfusion and in 1-3 days after perfusion was returned to the control level. Leucocyte were also decreased during perfusion, but it was increased progessively after perfusion and in 1-3 days after perfusion exceed the control level. This increase was resulted from postoperative infection of the wound, but its analysis were not changed significantly.

• Journal of Chest Surgery
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• v.3 no.2
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• pp.73-90
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• 1970

Clinical perfusion data on 16 cases of cardiopulmonary bypass using Sigmamotor pump and RyggKyvsgaard Oxygenator which performed at Seoul National University Hospital during the period of Aug. 1968 to Aug. 1970 was analized. AIl cases were hemodiluted and the perfusion was carried out under the normothermic condition. The age of the patients ranged between 6 and 43 years. The b:dy weight varied between 18.3 and 54.0 kg and the body surface area between 0.78 and 1. 59$M^2$. The priming solution was consiste:I with fresh ACD blood. Hartmann solution and Mannitol. The average amount of priming was approximately 2242 ml. The average hemodilution rate was 17%. The flow rate ranged from 1.7L to 3.5L/Min/$M^2$ and averaged 2.4L/Min/$M^2$ or 78mI/Min/kg. The duration of perfusion varied from 22 to 110 min with average of 56.9 minutes. Some hemodynamic responses were observed. The arterial pressure dropped immediately after the initiation of partial perfusion and was more marked after the total perfusion foIlowed by gradual increase to the safety level. The central venous pressure reflected the reduced blood volume especially in the cases of prolonged perfusion which lasted over 60 min. In most of the cases, red blood cell count decreased and white blood ceIl count increased after the perfusion. Hemoglobin level was decreased, averaging of 12.5mg%, Hct 3.3% and platelets count of 18% postoperatively. Plasma hemoglobin increased mildly, from pre-perfusion average value of 4. 06mg% to postperfusion value of 22.5mg%. Serum potassium was 4.4mEq/L pre-operatively and was decreased to 3.7mEq/L postoperatively. Five cases showed definite hypopotassemia immediately after the operation. Sodium and chloride decreased mildly. These electrolyte changes are thought to be related with hemodilution. diuretics and reduced blood volume during and after the perfusion. Arterial blood pH value revealed minimal to moderate elevation from preperfusion average value of 7.376 to 7.461 during perfusion and then 7.365 after perfusion. The pC02 and hicarbonate showed minimal to moderately lowered values. The total CO2 was decreased. Buffer base decreased during perfusion (Av. 42.6mEq/L) and further decreased after the perfusion (Av. 40.8mEq/L). These arterial blood acid base changes suggested that the metabolic acidosis was accompanied by respiratory alkalosis during and immediately after the perfusion. Authors belived that the acidosis could more effectively be corrected with the more additional dose of bicarbonate than we used by this study. The chest tune drainage during the first 24 hours following operation was 1158 ml in average. One case (Case No. 15) showd definite bleeding tendency and it was believed that the cause might be due to the defect of heparin and protamine titration. The average urinary out put during 24 hours post-perfusion was 1291ml. One case (Case No. ]) showed definite post perfusion oliguria. As conclusion hemodilution using fresh ACD blood. Hartmann and Mannitol solution added with Bivon and high flow rate unler normothermia. was thought to amelioratc the severity of mctabolic acidosis during and after perfusion with relatively satisfactory effect on the diuresis and bleeding tendency.