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

BACKGROUND: The overall rate of renal complications after surgery on the suprarenal aorta remains high. Possible mechanisms are, a reduction and maldistribution of renal blood flow, activation of the renin-angiotensin system, and the release of various mediators. In this study, changes in renal blood flow, local renal perfusion, the oxygen extraction ratio, and in renal function by furosemide following supraceliac aortic cross clamping and unclamping were observed. METHODS: A total of 13 mongrel dogs were divided into two groups; a control group (n = 7), and a furosemide group (n = 6). For aortic cross clamping the supraceliac aorta was exposed and a doppler flowmeter probe was placed on the left renal artery. A thermal diffusion microprobe was also inserted in the renal parenchyme to measure local renal perfusion. Sixty minutes after aortic cross clamping, systemic hemodynamic data, renal blood flow, and local renal perfusion were measured. These parameters were also repeatedly measured at 1, 2, 3, 4, 5, and 6 hours after unclamping. Biomarkers of renal dysfunction and injury (renin activity, creatinine, and Cystatin-C) were measured. RESULTS: No differences were observed between the two groups in terms of renal blood flow, local renal perfusion, and oxygen extraction ratio. Renal blood flow and perfusion did not recover to the baseline level after unclamping in either group. Plasma renin activity significantly reduced in the furosemide group 3 hours after clamping, but serum creatinine, and Cystatin-C concentrations were similar in the tow groups. CONCLUSIONS: We conclude that the administration of furosemide after supraceliac aortic unclamping to improve renal function is not effective in experimental dogs.
Animals ; Aorta ; Aortic Aneurysm ; Biomarkers ; Constriction* ; Creatinine ; Dogs* ; Flowmeters ; Furosemide* ; Hemodynamics ; Oxygen ; Perfusion ; Plasma ; Renal Artery ; Renal Circulation ; Renin ; Renin-Angiotensin System ; Thermal Diffusion

BACKGROUND: The incidence of renal insufficiency is reported about 18-27% during the thoracoabdominal aneurysm surgery. The possible mechanisms are reduction and maldistribution of renal blood flow, activation of renin angiotensin system, release of various mediators. In this study, we observed the effect of nicardipine, one of the calcium channel blockers that commonly used, on the systemic hemodynamics and the renal fuctions. METHODS: A total of 13 mongrel dogs were divided into two groups: control group (C, n = 7), nicardipine administration group (N, n = 6). After brachial arterial and Swan-Ganz catheterization, midline abdominal incision was made. For the aortic cross clamping the supraceilac aorta was exposed and the doppler flowmeter probe was placed on the left renal artery. The thermal diffusion microprobe was inserted in the renal parenchyme to measure local renal perfusion. At sixty minutes after aortic cross clamping, systemic hemodynamic data, renal blood flow and local renal perfusion were measured and at 1, 2, 3, 4, 5 and 6 hours after unclamping the same parameters were measured. RESULTS: There were no differences on renal blood flow, renal perfusion and oxygen extraction ratio between two groups. The renal blood flow and renal perfusion did not recover to the baseline level after unclamping in both groups. The plasma renin activity, serum creatinine concentration and cystatin-c did not show any difference between groups respectively. CONCLUSIONS: We concluded that the administration of nicardipine after supraceliac aortic unclamping to improve the renal function was not effective in experimental dogs.
Aneurysm ; Animals ; Aorta ; Calcium Channel Blockers ; Catheterization, Swan-Ganz ; Constriction* ; Creatinine ; Dogs* ; Flowmeters ; Hemodynamics* ; Incidence ; Nicardipine* ; Oxygen ; Perfusion ; Plasma ; Renal Artery ; Renal Circulation ; Renal Insufficiency ; Renin ; Renin-Angiotensin System ; Thermal Diffusion

BACKGROUND: The Pringle maneuver is traditionally used during the hepatectomy to reduce the blood loss. However, there have been no studies about local liver perfusion (LLP) and oxygen extraction ratio (ERO2) following hepatic ischemia and reperfusion. In this study, the changes in hepatic blood flow (HBF), LLP, ERO2 following hepatic ischemia and reperfusion were observed. And the effects of low dose nitroglycerin (NTG) were observed too. METHODS: A total of 14 mongrel dogs were divided into two groups; control group (C, n = 7), NTG administration group (N, n = 7), NTG administration was started 5 minutes before HBF occlusion. After femoral arterial and central venous catheterization, midline abdominal incision was made. Hepatic artery (HA) and portal vein (PV) were exposed to clamp and declamp. And then doppler flowmeter probes were applied on HA and PV to measure their blood flow and a thermal diffusion microprobe was inserted in the liver parenchyme to measure LLP. RESULTS: The HA and PV blood flow, LLP, and ERO2 were not different between two groups. However, HBF more increased compared to the baseline level in N group after reperfusion. In C group, LLP did not recover after reperfusion. The LLP in N group recovered to the baseline level after reperfusion. CONCLUSIONS: In conclusion, it was observed that the HBF increased and LLP recovered to the baseline level after reperfusion by administration of low dose NTG. The use of low dose NTG is safe and effective for hepatectomy.
Animals ; Catheterization, Central Venous ; Central Venous Catheters ; Dogs* ; Flowmeters ; Hepatectomy ; Hepatic Artery ; Ischemia ; Liver* ; Nitroglycerin* ; Oxygen* ; Perfusion* ; Portal Vein ; Reperfusion* ; Thermal Diffusion

BACKGROUND: Pringle maneuver and nitroglycerin (NTG) administration to reduce hemorrhage during hepatectomy may affect renal blood flow (RBF) and renal cortical perfusion (RCP) by reducing blood pressure (BP), perload and others. However, so far there have been no studies on RBF and RCP changes during and after hepatic vascular maneuver in hepatectomy. The purpose of this study was to evaluate the changes in RBF and RCP along with low dose (2 microgram/kg/min) NTG with or without low dose (3 microgram/kg/min) dopamine after the occlusion and reperfusion of hepatic blood flow. METHODS: Eighteen mongrel dogs were divided into three groups according to drug administration after hepatic reperfusion; control group (group C, n = 6), NTG group (group N, n = 6), and NTG with dopamine group (group N-D, n = 6). After femoral arterial and central venous catheterization, a midline abdominal incision was made, and the hepatic artery (HA) and the portal vein (PV) were exposed for clamping and declamping. Thereafter, the right renal artery was exposed, and a doppler probe for measuring RBF was placed around the right renal artery, and a thermal diffusion microprobe was inserted in the renal outer cortex to measure RCP. Hemodynamics, RBF and RCP, were repeatedly measured before and after HA and PV reperfusion. RESULTS: No significant change in heart rate was observed in any group. The BP decreased in all the groups after HA and PV occlusion. In group C, the BP recovered to the baseline level after hepatic reperfusion but not in groups N and N-D. The RBF and RCP decreased in all groups after HA andPV occlusion. The RBF increased compared to baseline in N-D after hepatic reperfusion, and the RCP increased versus baseline in N-D, 10 minutes after hepatic reperfusion. CONCLUSIONS: In conclusion, it was observed that the RBF and RCP increased compared to baseline by administering dopamine during HA and PV reperfusion. Therefore, the prophylactic administration of low dose dopamine during hepatectomy offers an effective method of protecting renal function.
Animals ; Blood Pressure ; Catheterization, Central Venous ; Central Venous Catheters ; Constriction ; Dogs* ; Dopamine* ; Heart Rate ; Hemodynamics ; Hemorrhage ; Hepatectomy ; Hepatic Artery ; Liver* ; Nitroglycerin* ; Perfusion* ; Portal Vein ; Renal Artery ; Renal Circulation* ; Reperfusion* ; Thermal Diffusion

PURPOSE: Various vasopressor agents are used to raise systemic vascular resistance (SVR) during liver transplantation. After grafted liver was reperfused, postreperfusion syndrome could be treated with various vasopressors. However, epinephrine can decrease the splanchnic perfusion and oxygen saturation and then hepatic blood flow would be jeopardized. Decreased hepatic blood flow might result in centrilobular necrosis which contributes to disruption of liver functions. We tried to know the effect of epinephrine on tissue perfusion of the liver. METHODS: In this study, measurement of hepatic microcirculation (HMC) and hemodynamic changes was performed in eight dogs to investigate the effect of vasopressors on hepatic microcirculation. Animals were divided into four groups in which low-dose epinephrine (0.05mug/Kg/min) and high-dose epinephrine (0.5mug/Kg/min) were randomly infused into the systemic vein and portal vein (1/6 of systemic dose) for ten minutes. Hepatic microcirculation was measured by Thermal Diffusion Probe. RESULTS: At low-dose systemic infusion of epinephrine, mean arterial bloodpressure (MABP), cardiac output (CO), and hepatic microcirculation (HMC) were significantly increased but systemic vascular resistance (SVR) was decreased. On high-dose epinephrine, MABP, CO (P=0.01), and SVR were significantly increased without changes of HMC. Intraportal infusion of low- and high-dose epinephrine increased hepatic vein pressure and SVR, respectively. CONCLUSION: These results would provide clues that systemic low-dose epinephrine infusion is enough to raise HMC and high-dose infusion of epinephrine to raise SVR could be used without jeopardizing HMC.
Animals ; Cardiac Output ; Dogs ; Epinephrine ; Hemodynamics ; Hepatic Veins ; Liver ; Liver Transplantation ; Microcirculation* ; Necrosis ; Oxygen ; Perfusion ; Portal Vein ; Thermal Diffusion* ; Transplants ; Vascular Resistance ; Vasoconstrictor Agents ; Veins

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

BACKGROUND: The measurement of perfusion is very important to understanding the physiology in the ischemic and reperfused tissue. However, no studies have been reported using a beating heart with a real time-continuous perfusion measurement system (QFlow(TM)400) to check local tissue perfusion so far. In this study, the changes in hemodynamics and local myocardial perfusion (LMP) after coronary reperfusion with nicardipine (a calcium channel blocker) administration were evaluated. METHODS: A total of 10 mongrel dogs were divided into two groups; group I (control group, n = 5), group II (nicardipine group, n = 5). After femoral arterial, pulmonary arterial and left ventricular catheterization, a left thoracotomy was performed. Next, the left anterior descending coronary artery (LAD) was exposed, and a thermal diffusion microprobe was inserted in the myocardium to measure LMP. RESULTS: In group II, blood pressure and systemic vascular resistance after LAD reperfusion were significantly decreased compared to group I. Cardiac output and stroke volume were more rapidly increased in group II, while left ventricular stroke work was decreased in group II. In group I, the LMP after LAD reperfusion did not recover to the baseline level, but the LMP did recover 20 minutes after LAD reperfusion and was increased more compared to the baseline level at 30 minutes after LAD reperfusion in group II. There were no significant differences in dP/dt between the two groups. CONCLUSIONS: We found that the LMP did not recover to the baseline level in the early state of LAD reperfusion; however, nicardipine administration increased the LMP after the early reperfusion period. Cardiac output and stroke volume were also more rapidly increased when nicardipine was administrated.
Animals ; Blood Pressure ; Calcium Channels ; Cardiac Output ; Catheterization ; Catheters ; Coronary Vessels ; Dogs* ; Heart ; Hemodynamics* ; Myocardial Reperfusion* ; Myocardium ; Nicardipine* ; Perfusion* ; Physiology ; Reperfusion ; Stroke ; Stroke Volume ; Thermal Diffusion ; Thoracotomy ; Vascular Resistance

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