Splanchnic Blood Flow In Patients Research Articles

Elevation of the head of bed reduces splanchnic blood flow in patients with intra-abdominal hypertension

BackgroundElevation of the head of bed (HOB) increases intra-abdominal pressure (IAP), but the effect of body position on abdominal splanchnic perfusion is not clear. The current study aimed to evaluate the effect of body position on the superior mesenteric artery (SMA) and the celiac artery (CA) blood flow by Doppler ultrasound in mechanically ventilated patients with intra-abdominal hypertension (IAH).MethodsThis prospective cohort study included 53 mechanically ventilated patients with IAH. IAP, hemodynamic variables, and Doppler parameters of the SMA and CA were measured in the supine position. The measurements were repeated after the HOB angle was raised to 15° for 5 min and similarly at HOB angles of 30° and 45°. Finally, the patient was returned to the supine and these variables were re-measured.ResultsThe median (interquartile range, IQR) superior mesenteric artery blood flow (SMABF) decreased from 269 (244–322) to 204 (183–234) mL/min and the median (IQR) celiac artery blood flow (CABF) from 424 (368–483) to 376 (332–472) mL/min (both p<0.0001) while median (IQR) IAP increased from 14(13–16) to 16(14–18) mmHg (p<0.0001) when the HOB angle was changed from 0° to 15°. However, SMABF and CABF were maintained at similar levels from 15° to 30°, despite median (IQR) IAP increased to 17(15–18) mmHg (p = 0.0002). Elevation from 30° to 45° further reduced median (IQR) SMABF from 200(169–244) to 164(139–212) mL/min and CABF from 389(310–438) to 291(241–383) mL/min (both p<0.0001), Meanwhile, median (IQR) IAP increased to 19(18–21) mmHg (p<0.0001).ConclusionsIn mechanically ventilated patients with IAH, progressive elevation of the HOB from a supine to semi-recumbent position was associated with a gradual reduction in splanchnic blood flow. However, the results indicate that splanchnic blood flow is not further reduced when the HOB is elevated from 15° to 30°.This study confirms the influence of head-up angle on blood flow of the splanchnic organs and may contribute to the selection of the optimal position in patients with abdominal hypertension.

Chronic intestinal ischemia and splanchnic blood-flow: Reference values and correlation with body-composition

To determine the splanchnic blood flow and oxygen uptake in healthy-subjects and patients and to relate the findings to body-composition. The total splanchnic blood flow (SBF) and oxygen uptake (SO₂U) were measured in 20 healthy volunteers (10 women) and 29 patients with suspected chronic intestinal ischemia (15 women), age 40-85 years, prior to and after a standard meal. The method is based on the Fick principle using the continuous infusion of an indicator (99mTechnetium-labelled mebrofenin) and catheterization of an artery and the hepatic vein. An angiography of the intestinal arteries was performed during the same investigation. A whole-body dual-energy x-ray absorptiometry scan was performed in healthy volunteers to determine body composition. Angiography revealed no atherosclerotic lesions in the intestinal arteries. The mean baseline SBF was 1087 mL/min (731-1390), and this value increased significantly to 1787 mL/min after the meal in healthy volunteers (P < 0.001). The baseline SBF in patients was 1080 mL/min, which increased to 1718 mL/min postprandially (P < 0.001). The baseline SBF was independent of age, sex, lean body mass and percentage of body fat. The mean meal-induced increase in SBF was equal to 282 mL/min + 5.4 mL/min × bodyweight, (P = 0.025). The SO₂U in healthy volunteers and patients was 50.7 mL/min and 48.0 mL/min, respectively, and these values increased to 77.5 mL/min and 75 mL/min postprandially, respectively. Both baseline and postprandial SO₂U were directly related to lean body mass. Age and sex exerted no impact on SO₂U. A direct correlation between body weight and the postprandial increase in SBF was observed. The effect of body weight should be considered in the diagnosis of chronic intestinal ischemia.

Effects of Fenoldopam Mesylate Infusion on Splanchnic Perfusion After Myocardial Revascularization on Cardiopulmonary Bypass: An Ultrasound Doppler Study

To measure the effects of fenoldopam mesylate infusion on splanchnic blood flow in patients undergoing myocardial revascularization with cardiopulmonary bypass. An experimental observational study. A single-institution community hospital. Eighteen patients undergoing on-pump coronary artery bypass graft surgery. Fenoldopam mesylate infusion (0.1 μg/kg/min). Blood flow through the celiac artery, superior mesenteric artery, portal vein and hepatic artery were assessed by means of Doppler measurements. The main hemodynamic variables were measured using echocardiography. The infusion of fenoldopam significantly increased the blood flow through both celiac and superior mesenteric arteries by decreasing vascular resistance. The percentage of cardiac output directed to these 2 vessels increased significantly; the increase through the superior mesenteric artery was greater compared with the celiac artery. Portal vein and hepatic artery blood flow also consistently increased. No significant variations were observed with respect to hemodynamic variables. The infusion of fenoldopam increased the flow through the celiac artery and superior mesenteric artery; the effect was higher for the latter. These changes did not affect the hemodynamic variables.

Comparison of Systemic and Renal Effects of Dopexamine and Dopamine in Norepinephrine-Treated Septic Shock

Vasopressor-induced vasoconstriction may compromise renal and splanchnic blood flow in patients with septic shock, resulting in secondary organ failures. The authors compared the effects of the vasodilatatory agent dopexamine against renal-dose dopamine and placebo in patients with norepinephrine therapy and septic shock, using 24-hour serum creatinine clearance (C(crea)) as a major endpoint. The primary hypothesis to be tested was that dopexamine is more effective than dopamine and that dopamine shows better effects than placebo regarding organ failures and C(crea). A prospective, randomized, controlled, double-blinded study. Intensive care unit in a tertiary care university hospital. Sixty-one patients with septic shock defined according to established criteria. Patients received either dopexamine (2 microg/kg/min, n = 20), dopamine (3 microg/kg/min, n = 21), or placebo (n = 20). The trial groups were similar in terms of baseline characteristics. The authors found no significant differences among the dopexamine, dopamine, and placebo groups with regard to a comprehensive number of renal function parameters including C(crea) and organ-failure scores. There was a significant increase in heart rate after dopexamine infusion; other hemodynamic parameters remained unchanged in the dopexamine group. In a post hoc analysis that included only patients with renal impairment at study inclusion (n = 28), patients who received dopamine showed significant improvements in C(crea) when compared with placebo. Dopexamine was not effective in this subgroup. Dopexamine is no more effective than dopamine or placebo regarding renal function in patients with septic shock requiring norepinephrine. Both therapies do not influence organ-failure scores.

Variability of splanchnic blood flow in patients with sepsis.

Previous studies on therapeutic interventions in sepsis have assumed stability of the measure of splanchnic blood flow throughout the study. We assessed the variability of splanchnic blood flow during stable global hemodynamics in eight patients with sepsis requiring treatment with dobutamine and/or norepinephrine. Prospective clinical study in an intensive care unit of a university hospital. Global and regional hemodynamics were measured at baseline, 2 h later, and 4 h later. Cardiac output was measured by transpulmonary thermodilution, intrathoracic blood volume as an indicator of cardiac preload, and total blood volume by the double indicator (thermo-dye) dilution technique. Total body oxygen consumption was assessed by indirect calorimetry using a metabolic cart. Splanchnic blood flow was measured by the continuous indocyanine green method, and gastric mucosal CO2 tension by gas tonometry. Neither absolute nor fractional splanchnic blood flow (as ratio of cardiac output) revealed significant global tendencies during the study period. However, variance component analysis showed that splanchnic blood flow determinations varied considerably within patients, for repeated measurements at 5-min intervals (standard error 31.1%) as well as for average values at 2-h intervals (25.6%). Stable global hemodynamics during a 4-h period in septic patients does not exclude marked changes in splanchnic blood measured by a hepatic venous catheter technique.

Does the optimization of cardiac output by fluid loading increase splanchnic blood flow?

We studied the effects of increasing cardiac output by fluid loading on splanchnic blood flow in patients with haemodynamically stabilized septic shock. Eight patients (five female, 39-86 yr) were assessed using a transpulmonary thermo-dye-dilution technique for the measurement of cardiac index (CI) intrathoracic blood volume (ITBV) as a marker of cardiac preload and total blood volume (TBV). Splanchnic blood flow was measured by the steady state indocyanine-green technique using a hepatic venous catheter. Gastric mucosal blood flow was estimated by regional carbon dioxide tension (PRCO2). Hydroxyethyl starch was infused to increase cardiac output while mean arterial pressure was kept constant. In parallel, mean norepinephrine dosage could be reduced from 0.59 to 0.33 microg kg(-1) min(-1). Mean (SD) TBV index increased from 2549 (365) to 3125 (447) ml m(-2), as did ITBV index from 888 (167) to 1075 (266) ml m(-2) and CI from 3.6 (1.0) to 4.6 (1.0) litre min(-1) m(-2). Despite marked individual differences, splanchnic blood flow did not change significantly neither absolutely (from 1.09 (0.96) to 1.19 (0.91) litre min(-1) m(-2)) nor fractionally as part of CI (from 28.4 (19.5) to 24.9 (16.3)%). Gastric mucosal PRCO2 increased from 7.7 (2.6) to 8.3 (3.1) kPa. The PCO2-gap, the difference between regional and end-tidal PCO2, increased slightly from 3.2 (2.7) to 3.4 (3.1) kPa. Thus, an increase in cardiac output as a result of fluid loading is not necessarily associated with an increase in splanchnic blood flow in patients with stabilized septic shock.

Prospective randomized study of drainage and resection on non-occlusive segmental portal hypertension in chronic pancreatitis

In chronic pancreatitis, compression of the splenic vein and superior mesenteric vein (SMV) by an inflammatory mass may cause segmental portal hypertension. Drainage and resection are the principles of surgery for chronic pancreatitis. This study was devised to evaluate the effect of drainage and resection on venous splanchnic blood flow in patients with non-occlusive segmental portal hypertension. In 14 of 30 patients with chronic pancreatitis predominantly involving the pancreatic head, segmental portal hypertension due to compression of the splenic vein and SMV was detected by means of indirect splenomesentericoportography and Doppler ultrasonography. None of these 14 patients had symptomatic gastric fundic varices. They were allocated randomly to surgical drainage or resection. Median follow-up was 30 (range 12-48) months. In the resection group, mean(s.d.) splenic vein blood flow increased from 316(46) ml/min before operation to 396(57) ml/min at follow-up (P < 0.01). In the drainage group, preoperative splenic vein blood flow (318(37) ml/min) was not increased after operation (322(37) ml/min). Mean(s.d.) SMV flow increased from 292(42) ml/min before operation to 436(64) ml/min at follow-up (P < 0.01) in the resection group. In the drainage group mean(s.d.) SMV blood flow was 296(32) ml/min before operation and 314(34) ml/min at follow-up. No patient developed fundic gastric varices during follow-up. In non-occlusive segmental portal hypertension due to chronic pancreatitis, resection, but not drainage, restores normal venous splanchnic blood flow.

Glucagon selectively increases splanchnic blood flow in patients with well-compensated cirrhosis.

To delineate the circulatory effects of glucagon in cirrhosis, we infused two moderately supraphysiological doses of this hormone into 19 patients with cirrhosis and determined hemodynamic responses. Patients were divided into a group with good liver function (Pugh Class A, n = 8) and poorer function (Pugh Class B and C, n = 11). All patients received glucagon at 10 ng per kg per min for 20 min, then 20 ng per kg per min for a further 20 min. These doses raised serum glucagon levels to a similar degree in both groups of patients. Serum glucose levels also rose in both groups but to a lesser degree in Class BC patients. Serum noradrenaline and adrenaline remained unchanged in both groups. Heart rate, mean arterial pressure, cardiac index, systemic vascular resistance, hepatic venous pressure gradient and hepatic blood flow were measured basally and during the second glucagon infusion. None of these measurements significantly changed in either group of patients. Azygos and renal venous blood flow were measured basally and during the first and second infusions. Azygos flow increased significantly only in Group A patients: basal, 0.32 +/- 0.03 liter per min; first infusion, 0.40 +/- 0.06 liter per min; second infusion, 0.49 +/- 0.07 liter per min. Corresponding values in Group BC patients were: 0.54 +/- 0.08, 0.54 +/- 0.08 and 0.52 +/- 0.08 liter per min. Renal blood flow did not change significantly. One patient with a portacaval shunt increased superior mesenteric venous flow from 0.78 liter per min to 0.95 liter per min with glucagon.(ABSTRACT TRUNCATED AT 250 WORDS)

Splanchnic blood flow in patients with abdominal angina before and after arterial reconstruction. A proposal for a diagnostic test.

The diagnostic value of determining the splanchnic blood flow (SBF) and oxygen uptake before and after a test meal in patients suspected of abdominal angina was investigated in 15 patients with unexplained abdominal pain. Six patients with typical abdominal angina and occlusive lesions of two or three splanchnic arteries were investigated before and after successful arterial reconstruction. Five patients with less severe arterial lesions were classified as suspected of abdominal angina and four patients with eventual normal arteriography served as controls. No significant difference was found in fasting SBF between the three groups. Postprandial SBF rose in the controls and in the abdominal angina suspected group, but not in the patients with abdominal angina. After arterial reconstruction fasting SBF was higher than before and postprandial SBF rose to the level of the controls. No difference in oxygen uptake before or after test meal was seen in any of the groups or after arterial reconstruction.