OBJECTIVE: The brain temperature is about 0.4-1 degrees C higher than that of the other peripheral body area. But most of these results have been obtained in normothermic condition. The objective of this study is to evaluate the temperature difference between the brain and axilla, in patients under hypothermia. METHODS: Sixty-three patients(37 women and 26 men) who underwent craniotomy with implantation of the thermal diffusion flowmetry sensor were included in this study. The temperature of the cerebral cortex and axilla was measured every 2 hours, simultaneously. The patient group was divided according to axillary temperature hyperthermia(over 38 degrees C), normothermia(36-38 degrees C) and hypothermia(under 36 degrees C). Total 1671 paired sample data were collected and analyzed. RESULTS: The temperature difference between the cerebral cortex and the axilla was 0.45+/-1.04 degrees C in hyperthermic patients, 0.97+/-1.1 degrees C in normothermic patients and 1.04+/-0.81 degrees C in hypothermic patients. The temperature difference has statistical significance in each group(unpaired t-test, p<0.05). CONCLUSION: From our study the temperature difference between the brain and the axilla in hypothermic condition increased more than that of normothermic state. And in hyperthermic condition, the temperature difference decreased.
Axilla* ; Brain* ; Cerebral Cortex ; Craniotomy ; Female ; Fever ; Humans ; Hypothermia* ; Rheology ; Thermal Diffusion

BACKGROUND: It is believed that the brain temperature is about 1oC higher than the peripheral temperature. However the result has been mostly obtained in normothermia patients. The objective of this study was to evaluate whether the brain and axillary temperature difference would be increased or decreased in hypothermic patients. METHODS: Sixty-six patients who underwent a craniotomy with implantation of the thermal diffusion flowmetry sensor (SABER 2000; Flowtornics, Phonics, USA) were included in this study. The temperature of the cerebral cortex and axilla were measured simultaneously every 2 hours. The patient groups were divided according to their axillary temperature, hyperthermia (over 38oC: 127 paired data), normothermia (36 38oC: 1626 paired data) and hypothermia (under 36oC: 285 paired data). A total 2048 paired sample data were collected and analyzed. RESULTS: The temperature difference between the cerebral cortex and the axilla was 0.46 +/- 1.04 oC in hyperthermic patients, 0.89 +/- 1.65 C in normothermia patients and 1.04 +/- 0.82 C in hypothermic patients. The temperature difference has statistical significance in each group (unpaired t-test, P > 0.05). CONCLSIONS: Our results demonstrate that the temperature difference in the brain shows a difference according to the patients, body temperature. In normothermia the temperature difference between the brain and the axilla was about 1oC. However in a hyperthermic state, the temperature difference decreased and in a hypothermic state, the temperature difference increased.
Axilla* ; Body Temperature* ; Brain* ; Cerebral Cortex ; Craniotomy ; Fever ; Humans ; Hypothermia ; Rheology ; Thermal Diffusion

BACKGROUND: This study was done to evaluate the sole effect of norepinephrine on the regional myocardial perfusion during displacement of the porcine beating heart using thermal diffusion method. METHODS: Thermal diffusion probe was inserted into the anterior myocardial wall during 20 procedures in 10 male pigs (30-35 kg). The measurements of regional myocardial perfusion and hemodynamic parameters were performed after complete instrumentation (baseline), after displacement of the beating heart anteriorly, and 5 and 15 minutes after norepinephrine infusion, titrated to restore baseline mean arterial pressure (MAP). RESULTS: Norepinephrine infusion reversed the decrease in MAP and myocardial perfusion, caused by displacement of the beating heart (62 +/- 3% to 115 +/- 4% of baseline, P < 0.01; 41 +/- 5% to 125 +/- 4% of baseline, P < 0.05, respectively). CONCLUSIONS: Restoration of MAP with norepinephrine infusion without any preload augmentation reversed deterioration in regional myocardial perfusion during displacement of the porcine beating heart.
Arterial Pressure ; Displacement (Psychology) ; Heart ; Hemodynamics ; Humans ; Male ; Norepinephrine ; ortho-Aminobenzoates ; Perfusion ; Swine ; Thermal Diffusion

No abstract available.
Diffusion Tensor Imaging* ; Diffusion*

A model theory of passive-targeted drug delivery in sphere-shaped solid tumors is introduced on the basis of Fick's law of diffusion, with appropriate boundary and initial conditions. For a uniform initial concentration inside the tumor, the concentration is obtained as a function of time and radial position. The concentration is shown to approach the equilibrium distribution as the time elapses, as is expected by the Gedanken Experiment. The time-evolution rate is found to be determined by the diffusion coefficient of the drug in the tissue, the size of the tumor, the volume of the drug-injected region, and the concentration gradient at the boundary.
Diffusion ; Jurisprudence

No abstract available.
Diffusion* ; Teicoplanin*

BACKGROUND: The measurement of perfusion is very important to understand the physiology of the tissue level. The QFlow(TM)400 perfusion measurement system is able to measure local tissue perfusion. The aim of this study was to validate thermal diffusion microprobe (TDM) in estimating myocardial blood flow during coronary artery occlusion and reperfusion in an animal beating heart model. METHODS: A total of 5 mongrel dogs were entered into the study. A left thoracotomy was performed under general anesthesia. After the left anterior descending coronary artery (LAD) was exposed, a TDM was inserted in the myocardium at the exposed LAD distributed area. The local myocardial perfusion was measured before, during and after LAD occlusion. To find the usefulness of TDM in a beating heart, k values were checked during the study. The k value or tissue conductivity should not exceed 6.23 mW/cmoC in this system. RESULTS: All the k values were below 6.23 mW/cmdegreesC in this study. Baseline local myocardial perfusion was 52.0 +/- 18.3 ml/min/100 g. During LAD occlusion, the local myocardial perfusion was decreased to 18.4 +/- 12.0 ml/min/100 g. At 10, 20 and 30 minutes after LAD reperfusion, the perfusion was recovered to 38.5 +/- 23.2, 27.2 +/- 17.4 and 36.2 +/- 17.2 ml/min/100 g, respectively, but the values at 20 and 30 minutes of reperfusion were significantly lower compared to baseline value. CONCLUSIONS: We could use the QFlow(TM)400 perfusion measurement system to measure myocardial injury produced by ischemia and subsequent reperfusion in a beating heart. With this system, we found that the local myocardial perfusion was not recovered to the baseline level in early state of the coronary reperfusion.
Anesthesia, General ; Animals ; Coronary Vessels* ; Dogs ; Heart* ; Ischemia ; Myocardial Reperfusion ; Myocardium ; Perfusion* ; Physiology ; Reperfusion* ; Thermal Diffusion* ; Thoracotomy

BACKGROUND: To reduce massive blood loss during a hepatectomy, many anesthesiologists have used the technique of low central venous pressure maintenance by administration of low dose nitroglycerin (NTG) and/or intravenous fluid reduction. However, so far there have been no studies about local liver perfusion (LLP) changes after hepatic artery (HA) or portal vein (PV) reperfusion in patients receiving nitroglycerin administration. In this study, the changes in hemodynamics and LLP following HA and PV reperfusion along with low dose (2micro gram/kg/min) NTG administration in dogs were observed. METHODS: A total of 20 mongrel dogs were divided into four groups; HA occlusion and reperfusion group (H, n = 5), NTG administration group during the reperfusion on H (H-NTG, n = 5), PV occlusion and reperfusion group (P, n = 5), NTG administration group during the reperfusion on P (P-NTG, n = 5). After femoral and pulmonary arterial catheterization, a midline abdominal incision was made. HA and PV were exposed to clamp and declamp. A thermal diffusion microprobe was inserted in the liver parenchyme to measure LLP. RESULTS: The PV blood flow was not changed after HA occlusion, but HA blood flow increased after PV occlusion. The LLP decreased after HA and PV occlusion. The LLP recovered to the baseline level in group H-NTG after HA reperfusion, but the LLP was more increased compared to the baseline level in group H. In group P, the LLP did not recover after PV reperfusion, but the LLP in group P-NTG recovered to the baseline level after PV reperfusion. CONCLUSIONS: In conclusion, it was observed that the LLP recovered to the baseline level by administration of NTG after PV reperfusion. However, the LLP did not increase after HA reperfusion by administration of low dose NTG.
Animals ; Catheterization ; Catheters ; Central Venous Pressure ; Dogs* ; Hemodynamics* ; Hepatectomy ; Hepatic Artery* ; Humans ; Liver* ; Nitroglycerin* ; Perfusion* ; Portal Vein* ; Reperfusion* ; Thermal Diffusion

OBJECTIVE: The tolerance and the safety of temporary arterial occlusion in aneurysm surgery are variable among patients because of individual variations of their collateral circulation. We recorded continuous intraoperative regional cortical blood flow(rCoBF) with thermal diffusion flowmetry(TDF) in patients with aneurysmal subarachnoid hemorrhage to determine a safe time limit for temporary occlusion in relation to rCoBF. PATIENTS AND METHODS: From Oct. '97 to Sep. '98, 40 patients with cerebral aneurysm at anterior cerebral artery(ACA) or middle cerebral artery(MCA) were included in this study. The TDF probe was placed over the cortex which was supplied by corresponding arteries. For data analysis, we included only the patients with Hunt-Hess grade I or II on admission. RESULTS: The total occlusion time of the proximal parent artery in 24 patients was on average 21.8 minutes, ranging between 9 minutes and 68 minutes. The lowest rCoBF in relation to temporary occlusion time in patient with excellent outcome was as follows: 0ml/100mg/min for 13 minutes and 6ml/100mg/min(11% of basal rCoBF) for 18 minutes in the middle cerebral artery and bilateral anterior cerebral arteries, respectively. The multiple regression equation regarding safe time for temporary clipping was as follows: safe time = 5.5 + 0.06 X rCoBF intra + 0.25 X rCoBF pre. And reperfusion time for the full recovery of rCoBF was within 4 minute in most cases, except some no-reflow cases. CONCLUSION: In our study with proper brain protection, a safe time limit for temporary occlusion was calculated 18 minutes even at 0ml/100mg/min in the MCA and this technique seems to be very useful to detect a continuous real time change of rCoBF during aneurysm surgery.
Aneurysm* ; Anterior Cerebral Artery ; Arteries ; Brain ; Collateral Circulation ; Humans ; Intracranial Aneurysm ; Middle Cerebral Artery ; Parents ; Reperfusion ; Statistics as Topic ; Subarachnoid Hemorrhage ; Thermal Diffusion

BACKGROUND: Carbon dioxide is a potent cerebral vasodilator. The change of carbon dioxide partial pressure may influence the intracranial pressure and the patients' neurological outcome. There are few reports about the influence of end-tidal CO2 (ETCO2), arterial CO2 (PaCO2) and its pressure difference P(a-ET)CO2 during a craniotomy on the Glasgow coma scale (GCS) score for evaluation of neurological status. In this study, authors tried to discover the influence of PaCO2, PETCO2, and P(a-ET)CO2 on neurological outcome. METHODS: The data of PaCO2 and PETCO2 and P(a-ET)CO2 during a craniotomy was saved. The correlations between each parameter, the GCS score and rCoBF were analyzed. To prevent a direct effect on carbon dioxide tension, blood pressure and body temperature were maintained within a normal range. At the same time, we inserted a probe of the thermal diffusion flowmetry monitor in the subdural space to monitor the regional cortical cerebral blood flow (rCoBF). All the data was saved simultaneously, at the moment of dura closure. RESULTS: There was a fair correlation between the PaCO2 and PETCO2. A low PaCO2 level correlated well with a good GCS score but, not with PETCO2. The mean P(a-ET)CO2 value was 4.4 +/- 3.1 mmHg. The high P(a-ET)CO2 level correlated well with a poor GCS score. High rCoBF correlated well with a good GCS score. However, the changes of PaCO2 and PETCO2 showed no correlations with the rCoBF. CONCLUSIONS: As a result, if we decrease the PaCO2 level by hyperventilation and increase the rCoBF level through proper management during anesthesia, we can improve the patients' neurological outcome.
Anesthesia ; Blood Pressure ; Body Temperature ; Carbon Dioxide ; Craniotomy* ; Glasgow Coma Scale ; Humans ; Hyperventilation ; Intracranial Pressure ; Partial Pressure ; Prognosis* ; Reference Values ; Rheology ; Subdural Space ; Thermal Diffusion