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At least 73 records · Page 4Linked to original sources
PubMed1984

Renal and splanchnic circulation during infrarenal aortic cross-clamping.

The effect of infrarenal cross-clamping of the aorta on regional splanchnic and renal circulations was studied in seven dogs. Regional blood flow was determined with differentially labeled microspheres (9 and 15 micron in diameter) that were injected simultaneously into the left atrium. Blood flow was measured 30 minutes after surgical preparation was completed (stage I), 20 minutes after infrarenal aortic cross-clamping (stage II), and 20 minutes after supplemented sodium nitroprusside infusion (stage III). Infrarenal aortic cross-clamping was accompanied by a slight increase in the cardiac output (CO) without significant changes in mean arterial pressure (MAP). Blood flow through the gut, hepatic artery, and cortical layer of the kidneys, as determined with 15-micron spheres, was not changed. Nonentrapment of 9-micron spheres in the gut and renal cortex was increased substantially. Blood flow through the juxtamedullary layer of the kidneys was increased. Sodium nitroprusside supplementation decreased MAP by 30%; CO values returned to baseline level. Hepatic artery blood flow, compared with both baseline values and values during aortic cross-clamping, increased significantly. Blood flow, determined with 15-micron spheres, through the gut and renal cortex did not change, and nonentrapment of 9-micron spheres decreased to baseline values. The data suggest a certain shift of blood flow to the juxtamedullary layer of the kidneys during aortic cross-clamping and normalization of intrarenal blood flow distribution during supplemented sodium nitroprusside infusion. Controlled vasoplegia with sodium nitroprusside may help modify peripheral circulatory disturbances in the kidneys and splanchnic system during infrarenal aortic cross-clamping.

Animals↗
PubMed1999

Splanchnic circulation and regional sympathetic outflow during peroperative PEEP ventilation in humans.

The splanchnic organs represent a major target for sympathetic outflow and an important region for haemodynamic effects on cardiovascular homeostasis. We have studied regional haemodynamic and sympathetic changes in the splanchnic bed during standardized circulatory stress from positive end-expiratory pressure ventilation (PEEP). We investigated eight patients undergoing major upper abdominal surgery using a radiotracer method to measure plasma spillover of norepinephrine as an index of sympathetic nerve activity using arterial, portal and hepatic venous blood sampling. Mesenteric and hepatic perfusion were measured by ultrasound transit time flowmetry and blood-gas analyses. Steady state measurements were performed before and during PEEP ventilation at 10 cm H2O. Plasma spillover of norepinephrine in the mesenteric and hepatic organs represented mean 49 (SEM 8)% and 7 (2)%, respectively, of systemic norepinephrine spillover at baseline, and PEEP ventilation did not cause any significant changes. However, PEEP ventilation significantly decreased portal venous blood flow while hepatic blood flow was preserved by a compensatory increase in hepatic arterial blood flow. Mesenteric and hepatic oxygen delivery changed according to blood flow, and there were no changes in regional oxygen consumption. Thus PEEP ventilation altered mesenteric and hepatic perfusion, independent of any change in corresponding sympathetic nerve activity. Regulation of hepatic blood supply, not related to sympathetic activity, maintained liver oxygenation during PEEP ventilation despite a simultaneous decrease in mesenteric perfusion.

Adult↗
PubMed1994

Meal induced changes in hepatic and splanchnic circulation: a noninvasive Doppler study in normal humans.

The haemodynamic effects of a meal on the splanchnic and hepatic circulation were evaluated in 30 healthy volunteers, using Doppler ultrasonography. The resistance index (RI) of the superior mesenteric artery and of the left and right intrahepatic arteries, the portal vein blood flow as well as the ratio between maximal velocity in the left and right intrahepatic arteries and the adjacent portal vein were measured initially, then 15, 30, 45, and 60 min after the ingestion of a standard balanced liquid meal. Postprandial haemodynamic changes were maximal 30 min after the meal; at that time, mesenteric artery RI decreased significantly [mean -11% (SEM 14%)] whereas portal vein blood flow increased markedly [mean +79% (SEM 14%)]; a significant increase in hepatic artery RI was observed in both liver lobes. The ratio between maximal velocities of the intrahepatic artery and the intrahepatic portal vein was reduced significantly; this ratio decreased more markedly in the right lobe of the liver. These findings would suggest that there was an adaptation of hepatic artery to portal vein blood flow after a meal. The subsequent increase in intrahepatic portal vein flow velocity was found to be greater in the right lobe of the liver.

Adult↗
PubMed2002

Evaluation of the splanchnic circulation with indocyanine green pharmacokinetics in liver transplant patients.

Although indocyanine green (ICG) can be used to estimate cardiac output (CO) and blood volume independently, a recirculatory multicompartmental ICG model enables description of these and additional intravascular factors. This model was used to describe the effect of end-stage liver disease (ESLD) on systemic and splanchnic hemodynamics in patients undergoing orthotopic liver transplantation. ICG disposition was determined during the dissection phase in six patients with ESLD undergoing orthotopic liver transplantation and six healthy adult living liver donors. After injecting ICG, plasma concentrations were obtained for approximately 10 to 12 minutes by noninvasive pulse dye densitometry. The recirculatory model characterizes three distinct intravascular circuits: lumped parallel fast (presumably nonsplanchnic circulation) and slow peripheral (splanchnic) circuits and a central circuit (central blood volume). Mean transit time (MTT) in the fast peripheral circuit was not different in patients with ESLD and controls. However, ESLD resulted in a significant decrease in MTT in the central (0.11 +/- 0.028 [SD] v 0.24 +/- 0.094 minutes in controls; P <.001) and slow peripheral circuit (0.67 +/- 0.41 v 1.37 +/- 0.37 minutes in controls; P <.001) because of increased flows to the central and slow peripheral circuits. These findings are consistent with the described hyperdynamic systemic and splanchnic circulations in patients with ESLD. In conclusion, the ICG model is able to derive estimates of not only blood volume and CO, but also splanchnic hemodynamics under different physiological conditions. This model can be a useful tool to evaluate the effect of pharmacological manipulation of splanchnic hemodynamics.

Blood Volume↗
PubMed2001

Alterations in hemodynamics and hepatic and splanchnic circulation during laparoscopy in rats.

BACKGROUND: There is growing evidence that a pneumoperitoneum with increased intraabdominal pressure exerts adverse cardiovascular and splanchnic circulatory effects, whereby portal blood flow, in particular, is disturbed. METHODS: Cardiovascular hemodynamics and the blood flow of hollow viscus and solid organs were evaluated in rats undergoing laparotomy, followed by diagnostic carbon dioxide (CO2) laparoscopy with an intraabdominal pressure of either 4 or 10 mmHg and rapid desufflation of the abdominal cavity. The method we employed used g-labeled microspheres and conventional hemodynamic measurements. RESULTS: During CO2 laparoscopy, cardiac output and mean arterial pressure were significantly reduced to between 20.5% and 25% and 14.8% and 18% respectively. After rapid desufflation, cardiovascular hemodynamics normalized to baseline values. During laparoscopy, blood flow in the hollow viscus organs was less disturbed than that in the solid organs. Although small and large bowel blood flow was reduced significantly (26.6% and 23.9%, respectively), gastric blood flow remained unchanged. The decreases in the liver, spleen, pancreas, and kidney circulation were 29-37.2%, 37.6-64.6%, 51.2-57.5%, and 34.8-40.6%, respectively. Total hepatic blood flow was influenced predominantly by portal blood flow, which was particularly decreased; hepatic arterial flow remained stable. CONCLUSIONS: Severe alterations in cardiovascular hemodynamics, and to hepatic and splanchnic circulation occur rapidly during CO2 laparoscopy. It can be presumed that both increased intraabdominal pressure and hypercapnia are the main factors underlying these disturbances.

Animals↗
PubMed1990

Effect of human epidermal growth factor (hEGF) on splanchnic circulation in dogs.

The effect of intravenous administration of human epidermal growth factor on the splanchnic blood flows was examined in anesthetized dogs, using an ultrasonic transit-time volume flow meter. Human epidermal growth factor (0.1, 0.5 and 1 microgram/kg) significantly increased blood flows in the portal vein (36.9 +/- 7.4% at 1 microgram/kg) and the superior mesenteric artery (49.0 +/- 16.8% at 1 microgram/kg). Systemic blood pressure monitored simultaneously was significantly decreased (8.4 +/- 1.2% at 1 microgram/kg). This study is the first to demonstrate that intravenous administration of epidermal growth factor increases the portal venous blood flow.

Animals↗
PubMed1998

Vasoconstrictor actions of atrial natriuretic peptide in the splanchnic circulation of anesthetized dogs.

Intravenous atrial natriuretic peptide (ANP) usually results in splanchnic vasoconstriction in humans or experimental animals that is accompanied by falls in blood pressure and/or cardiac output. To determine direct in vivo effects in the present study, ANP was infused (12 ng. kg-1. min-1) directly into the mesenteric (iMA) and hepatic (iHA) arterial beds of anesthetized dogs, thereby minimizing changes in blood pressure. Over the first 2 min of iMA infusion, rate of change in mesenteric vascular resistance was 19.6 +/- 5.4 mmHg. l-1. min-1/min, reaching a maximum increase in resistance of 22 +/- 4% compared with baseline after approximately 10 min. There was no evidence of vasodilatation at any stage. The mesenteric response was similar whether ANP was infused iMA, iHA, or via the femoral vein (30 ng. kg-1. min-1). In contrast, hepatic vasoconstrictor response to ANP infusion iHA or into the portal vein was only evident after approximately 5 min, reaching a maximum increase in hepatic vascular resistance of 11 +/- 6% after approximately 15 min iHA infusion. When preinfused through the gut vasculature (iMA), ANP increased hepatic vascular resistance earlier and reached similar levels (14 +/- 3%), despite a lower arterial concentration of ANP. It is proposed that a vasoconstrictor agent from the intestinal circulation contributed to ANP-induced splanchnic vasoconstriction.

Animals↗
PubMed1990

Characterization of norepinephrine sensitivity in the maternal splanchnic circulation during pregnancy.

Vascular sensitivity to exogenous norepinephrine and transmural nerve stimulation was studied in the splanchnic bed of nonpregnant, early pregnant, and late pregnant rats. Resistance-size mesenteric arteries were removed from late pregnant (18 to 20 days), early pregnant (7 days), and nonpregnant cycling rats and mounted in a myograph system, which permits the precise setting of vessel circumference for the determination of norepinephrine sensitivity. Norepinephrine dose-response curves and frequency-response curves for transmural nerve stimulation were obtained in the presence and absence of cocaine, a specific inhibitor of neuronal reuptake. The mesenteric arteries of late pregnant rats were 1.5 times less sensitive to exogenous norepinephrine than arteries of both early pregnant and nonpregnant rats. Sensitivity to transmural nerve stimulation was decreased in both early and late pregnant rats compared with nonpregnant controls. Cocaine potentiated the response to both exogenous norepinephrine and transmural nerve stimulation in the pregnant rats so that responses between nonpregnant, early pregnant, and late pregnant rats were no longer different. This suggests a greater reuptake activity from pregnant rats. In conclusion, pregnancy is associated with a reduction in splanchnic norepinephrine sensitivity, which may be due partly to an increase in neuronal deactivation of norepinephrine. The maximum contractile response to norepinephrine also was decreased in late pregnancy, which suggests additional mechanisms for changes in norepinephrine vascular sensitivity.

Animals↗
PubMed1981

The splanchnic circulation: intrinsic regulation.

Several mechanisms are involved in the intrinsic regulation of splanchnic blood flows. Of these, myogenic, metabolic, and hormonal factors appear particularly important. The relative contributions of these elements vary with the status of the tissue. Myogenic and metabolic mechanisms prevail during stress states such as arterial pressure reduction or venous pressure elevation, thereby regulating microvascular pressures and O2 exchange. During periods of enhanced functional activity, hormonal and metabolic mechanisms appear to work in concert to assure adequate delivery of nutrients and O2 to, and removal of metabolites and absorbed elements from, the active tissue.

Animals↗
PubMed2001

[Hemodynamic monitoring of splanchnic circulation--does the benefit outweight risk of of regional circulation monitoring?].

Over the last 20 years there has been increasing interest in the pivotal role of the splanchnic region in the development of SIRS, sepsis and multiple organ failure. One key question is how to monitor and detect in good time regional splanchnic perfusion, oxygenation and impaired function of liver and gut, so as to start appropriate therapeutic measures. This review describes the pathophysiological background of impaired splanchnic perfusion. It focuses on the advantages and risks of methods of monitoring splanchnic perfusion or oxygenation and considers them regarding clinical relevance and usefulness. Special emphasis is laid on gastric tonometry. Despite all the restrictions and the criticism which can be levelled at this method, it remains the only way of monitoring splanchnic perfusion and oxygenation that is currently applicable in clinical routine. The data gained can be useful if clinicians are aware of the weak points of tonometry and consider the data in the overall clinical picture. When this is done, the patient can profit from gastric tonometry and the benefits outweigh the risks.

Hemodynamics↗