Vein Blood Flow Rate Research Articles

Effects of upper limb exercise programs on the arteriovenous fistula in patients on hemodialysis: A systematic review and meta-analysis.

The arteriovenous fistula (AVF) is a commonly used vascular access for chronic kidney disease (CKD) patients; exercise interventions may boost its maturation and help in its maintenance. A systematic review and meta-analysis of clinical trials on the effects of upper limb exercise programs on the AVF was conducted. The primary outcomes were draining vein diameter (DVD) and draining vein blood flow rate (DVBFR), and secondary outcomes were handgrip strength (HGS) and brachial artery flow rate (BAFR). Quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Four studies met the inclusion criteria. When compared to usual care groups, the experimental groups did not improve DVD (mean difference [MD] 0.23, confidence interval [CI] -0.20-0.65). There were significant differences in DVBFR (mL/min) according to the fixed-effect model (MD 141.13, CI 36.84-245.42). HGS (kg) was significantly different between groups (MD 2.95, CI 0.55-5.35), but BAFR (mL/min) was not (MD 91.65, CI -94.72-278.01). Although exercise programs did not improve DVD and BAFR, they increased muscle strength and DVBFR. Therefore, experimental exercise programs should be emphasized for AVF maturation and maintenance.Research Registry number: reviewregistry924.

Synthesis and evaluation of Pt/rGO as the anode electrode in abiotic glucose fuel cell: Near to the human body physiological condition

In this research, abiotic catalyst 40 wt% Pt/rGO is successfully synthesized via chemical reduction method with an average particle size of 3 nm (characterized by TEM and XRD), and activity of it as anode catalyst for glucose oxidation is evaluated in phosphate-buffered saline (PBS, pH = 7.4) in the presence of 5 mM glucose (near-human body physiological concentrations).The fuel cell testing is carried out in a two-chamber abiotic glucose fuel cell (AGFC) utilizing Pt/rGO as the anode catalyst and PBS/glucose as the feed. Furthermore, effect of circulated fuel (based on human arm's vein blood flow rate, 0.33 mLs−1) is also investigated for implantable purposes and is compared to stationary fuel; 10% increase in the AGFC voltage in contrast to 23% cell voltage drop respectively under 0.01 mAcm−2 current density over 15 h. Results indicate that Pt/rGO is a promising catalyst for AGFCs to power implantable devices.

DIAGNOSTIC OPPORTUNITIES OF PARA INFRARED SPECTROSCOPY IN FULL-TERM NEWBORNS DURING THERAPEUTIC HYPOTHERMIA IN THE POST ASPHYXIAL PERIOD

Introduction. Despite the achievements of neonatology, severe birth asphyxia in full-term infants is still associated with high mortality, long-term neurological morbidity and disability. In the algorithm of managing children with hypoxic-ischemic encephalopathy, it is important to use additional testing methods for early assessment of the severity of brain tissue damage. Assessment of cerebral oxygenation by near-infrared range (near-infrared spectroscopy, NIRS) has strong correlation with MRI brain perfusion in full-term newborns with hypoxic-ischemic encephalopathy. However, recommendations for the use of NIRS monitoring data in neonates with asphyxia and hypoxic-ischemic encephalopathy may differ in routine clinical practice.The objective of the study was to determine the relationship between brain perfusion measurements using NIRS and post asphyxial period characteristics (clinical symptoms, neurosonography, and cerebral artery Doppler ultrasound) in full-term newborns during therapeutic hypothermia.Materials and methods. Full-term infants with severe birth asphyxia who underwent therapeutic hypothermia were examined: 33 infants who had no signs of destructive brain damage, and 15 with destructive hypoxic-ischemic lesions. The results of the NIRS recordings in the post asphyxial period were compared with those of the clinical manifestations and the results of neurosonography and cerebral artery dopplerography.Results. Significant differences (p < 0.05) between observation groups were found regarding the registration of left frontal lobe NIRS: mean rSO2 (p=0.012; 84.01±2.64 % in children with destructive brain lesions) against 76.56±1.71 % in children without destructive lesions); the 25th percentile level of rSO2 (p=0.024, 80.47±2.89 % vs. 72.36±1.75 %, respectively), the 75th percentile of rSO2 (p=0.008, 88.20±2.66 vs. 80.88±1.78). There were no significant differences in the registration of NIRS indicators on the right side. Significant correlation relationships of average strength were recorded between the Galen vein blood flow rate (measurement on the 4th day of life) and the rSO2 average rates on the left (R=0.58), and on the right (R=0.52)Conclusions. Significant differences in the NIRS record scores of children groups with destructive hypoxic-ischemic changes in brain tissue and without destructive changes were observed (Max average rSO2 value on the left during destructive lesions formation). Max average rSO2 values were observed in both left- and right-sided monitoring and were associated with a higher rate of cerebral venous blood flow beyond hypothermia period.

MRI quantification of human fetal O2 delivery rate in the second and third trimesters of pregnancy.

PurposeThe purpose of this study was to estimate fetal O2 delivery rate in vivo across a range of gestational ages. Toward this, a calibration equation for T2‐based oximetry was derived.MethodsUmbilical cord blood of varying hematocrit (Hct) and oxygen saturation (HbO2) levels was prepared and T2 measured using a T2‐prepared balanced steady‐state free‐precession sequence at 1.5 T. The relationship between blood R2 = 1/T2, HbO2 and Hct was established based on the model . Experimental R2, HbO2, and Hct levels were fit to the model‐yielding values of k, and (R2 of plasma and erythrocytes). Umbilical vein T2 measured in vivo was then converted to HbO2, yielding—together with blood flow rate—the fetal O2 delivery rate in 22 pregnancies (gestational age 30 ± 3 weeks).ResultsConstants derived from the fit (R2 = 0.94) were k = 83.1 s−1, , and . The and k were found to be larger than those obtained for adult blood, likely the result of differences in dominant hemoglobin type. Data suggest that the use of adult blood calibration could entail errors up 10% in fetal blood HbO2. The average umbilical vein blood flow rate (89.5 ± 17.2 mL/min/kg), HbO2 (84 ± 7%,), and fetal O2 delivery rate (15.1 ± 3.8 mL O2/min/kg) were independent of gestational age. The fetal O2 delivery rate agreed well with the results obtained with invasive methods at term.ConclusionThe present work describes strategies for measuring umbilical vein blood flow rate and HbO2 in vivo and estimates fetal O2 delivery rate noninvasively with quantitative MRI during the second and third trimesters of pregnancy. Magn Reson Med 80:1148–1157, 2018. © 2018 International Society for Magnetic Resonance in Medicine.

Minimally-invasive catheterization of portal and mesenteric veins and abdominal aorta for quantitative determination of portal-drained viscera metabolism in pigs

A laparoscopic catheterization of portal and ileal veins as well as abdominal aorta was performed in eight pigs under general anesthesia for quantitative determination of portal-drained viscera metabolism. Three polyurethane catheters were introduced into the target vessels through an abdominal wall cannula using the guide catheter and wire. Surgery duration, length of incisions, and postoperative outcomes were recorded. On days 7 and 30, portal vein blood flow rates were measured by paraaminohippuric acid method. On day 35, a second laparoscopy was performed to monitor the setup of intraabdominal catheters. The laparoscopic procedures were completed with a mean operative time of 82 ± 9 min, and mean total incision size was 4.5 ± 0.5 cm. No major intraoperative or postoperative complications were encountered. The second laparoscopy showed that position and fixation of catheters remain stable 35 d after the surgical preparation. Portal vein blood flow remained similar (P > 0.05) from 7 to 30 d after the la...

Evaluation of hepatic uptake clearance of tetrodotoxin in the puffer fish Takifugu rubripes

In this study, we investigated the hepatic uptake clearance (CL uptake) of tetrodotoxin (TTX) in the marine puffer fish Takifugu rubripes by integration plot analysis after a single bolus injection of 0.25 mg TTX/kg body weight into the hepatic vein at 20 °C. The blood concentration of TTX decreased over time after the injection, from 1451 ± 45 ng/mL at 10 min to 364 ± 59 ng/mL at 60 min. TTX concentrations in the spleen and kidney decreased in parallel with the blood concentrations, whereas those in the muscle and skin remained almost the same throughout the experiment. In contrast, the TTX concentration in the liver gradually increased, reaching 1240 ± 90 ng/g liver at 60 min after injection. The amount of TTX that had accumulated in the liver 60 min after injection accounted for 63 ± 5% of the administered dose. Integration plot analysis indicated a CL uptake of 3.1 mL/min/kg body weight in the liver for TTX, a rate far below that of the hepatic portal vein blood flow rate (at most, 9%). This finding is consistent with negligible extraction of TTX by the liver. The results demonstrated conclusively that the liver-specific distribution of TTX in T. rubripes is achieved by removal from the systemic circulation, but not by the hepatic first-pass effect.

Doppler ultrasound measurements in the central circulation of anesthetized fetal sheep during obstruction of umbilical-placental blood flow.

To establish by Doppler ultrasound the effects of acute blockage of umbilical cord vessels on the fetal central circulation. Experimental study in anesthetized pregnant sheep. In 11 anesthetized pregnant sheep (0.66 of gestation), Doppler velocity profiles and/or venous flow rates were recorded in the ductus venosus, the fetal aorta, the umbilical arteries and the umbilical vein. This involved three phases. In Phase 1, the abdominal wall was closed (n = 9); Phase 2 was during fetoscopy after laparotomy (n = 8); Phase 3 was after coagulation of one of the umbilical arteries (n = 10). As an additional intervention in six fetuses, the umbilical cord was clamped for 5-15 s while blood flow velocity changes in the ductus venosus were observed. There were no significant differences between Doppler recordings in Phases 1 and 2. During Phase 3, the pulsatility index of the aorta and of the coagulated umbilical artery increased significantly. The umbilical vein blood flow rate was significantly reduced from a median of 408 (range, 243-575) mL/min/kg in Phase 1 to a median of 173 (range, 107-426) mL/min/kg in Phase 3, but the blood flow rate in the ductus venosus (median, 94; range, 56-148 mL/min/kg vs. median, 92; range, 33-237 mL/min/kg) remained unchanged. The ductus venosus/umbilical vein ratio increased from a median of 0.22 (range, 0.13-0.41) to 0.56 (range, 0.17-0.97) (P < 0.05). Compression of the cord (5-15 s) immediately reduced the time averaged maximum velocity in the ductus venosus from a mean of 51 (standard deviation, 11) cm/s to 20 (standard deviation, 6) cm/s (P < 0.001) without significant changes of the velocity profile. However, the pulsatility index increased from a mean of 0.55 (standard deviation, 0.19) to 1.89 (standard deviation, 0.73) (P < 0.001). Central venous flows in anesthetized fetal sheep are unaffected by laparotomy and hysterotomy. Obliteration of one umbilical artery increases the ductus venosus/umbilical vein volume flow (mL/min/kg) ratio. Compression of the umbilical cord shifts down blood flow velocity profiles in the ductus venosus, and the pulsatility index thus increases.

Doppler ultrasound evaluation of ductus venosus blood flow during acute hypoxemia in fetal lambs.

It has been demonstrated with invasive techniques in fetal lambs that the ratio of ductus venosus to umbilical vein blood flow rate (DV/UV ratio) increases during hypoxemia and infusion of catecholamines. Recently it was found in human fetuses using pulsed wave Doppler ultrasound equipment that the DV/UV ratio in fetuses with intrauterine growth restriction was significantly increased. The aim of the present study was to show in fetal lambs whether routine Doppler ultrasound devices were capable of determining the DV/UV ratio with sufficient reliability. The experiments were performed on seven near-term instrumented fetal lambs using pulsed wave Doppler ultrasound to measure flow rates (derived, in milliliters per min, from the intensity-weighted mean velocity (Vmean) and the vessel's cross-sectional area) in the ductus venosus and intra-abdominal umbilical vein. Fetal hypoxemia was induced by administering a low-oxygen gas to the ewe (5-7% oxygen, 2% carbon dioxide). Fetal arterial pO2 and heart rate decreased significantly during maternal hypoxia. The proportion of umbilical venous return passing through the ductus venous in controls was 36 +/- 5% (mean +/- SD). This increased to 53 +/- 6% (p < 0.001) because the umbilical venous blood flow fell during late hypoxemia when the heart rate had decreased by 20%. Severe hypoxemia tended to reduce the mean velocity (Vmean) and the minimum velocity (Vmin) (based on the maximum velocity envelope curve) in the ductus venosus, descending aorta and inferior vena cava. The pulsatility index of the umbilical artery significantly increased at the end of hypoxemia. We conclude that determination of the proportion of umbilical vein blood flow entering the ductus venosus by Doppler ultrasound in a clinical setting may contribute to the detection and evaluation of fetal distress.

Blood flow through the ductus venosus in singleton and multifetal pregnancies and in fetuses with intrauterine growth retardation

OBJECTIVE: It is known from animal experiments that blood flow through the ductus venosus changes with fetal strain. Therefore the ratio of umbilical vein to ductus venosus flow rate in human intrauterine growth retardation and multifetal pregnancies was investigated and compared with that in control subjects. STUDY DESIGN: Blood flow rates in the umbilical vein and in the ductus venosus, as well as peak velocity, minimum velocity, mean velocity, and pulsatility index (maximum velocity envelope curve) in the ductus venosus, were measured in women with normal pregnancies ( n = 55), intrauterine growth retardation ( n = 20), and multifetal pregnancies (10 women with 20 fetuses) with color Doppler ultrasonography. RESULTS: Average ductus venosus blood flow rates (mean ± SD), normalized for estimated fetal body weight, were 60 ± 30, 69 ± 35, and 77 ± 28 (ml · min –1 · kg –1) in control subjects, intrauterine growth retardation, and multifetal pregnancies, respectively. Umbilical vein blood flow rates amounted to 140 ± 59, 111 ± 54, and 141 ± 47 (ml · min –1 · kg –1). Both absolute flow rates increased with gestational age, whereas normalized flow rates decreased. The percentage of umbilical blood flow passing through the ductus venosus in the control group was 43% + 9%. It was significantly increased in both intrauterine growth retardation (62% ± 8%) and in multifetal pregnancies (55% ± 12%). Peak velocity, minimum velocity, mean velocity, and pulsatility index in the ductus venosus were not significantly different between groups. CONCLUSION: The increased ratio of ductus venosus blood flow to umbilical vein blood flow may indicate fetal strain. (Am J Obstet Gynecol 1998;178:943-9.)

Application of ultrasonic transit time flowmetry to the measurement of umbilical vein blood flow at caesarean section.

To determine the applicability of ultrasonic transit time flowmetry to the measurement at caesarean section of umbilical vein blood flow rate and to examine the relationship between flow rates and birthweight for gestational age. Umbilical vein blood flow was measured at caesarean section using a transonic time flow probe on a loop of the umbilical cord in 33 appropriate and 21 small for gestational age fetuses. The mean (SD) umbilical vein blood flow in the 54 fetuses was 78.4 (23.1) ml kg-1 min-1. There was a linear relation between umbilical vein blood flow measured by ultrasonic transit time flowmetry and birthweight (r = 0.63, P < 0.0001). The mean umbilical vein blood flow in appropriate for gestational age fetuses [90 (18) ml kg-1 min-1] was greater than that in the small for gestational age group [66 (23) ml kg-1 min-1], P < 0.04). Umbilical vein blood flow measurements obtained by the ultrasonic transit time flowmetry technique are simple to perform and compare well with reported values obtained by the Doppler ultrasound technique (when vessel diameter is greater than 4 mm). Umbilical venous blood flow rate is significantly lower in small for gestational age fetuses.

Influence of carbadox on fasting oxygen consumption by portal vein-drained organs and by the whole animal in growing pigs.

Fasting O2 consumption by the whole animal (W) and by portal vein-drained organs (PVDO) during the 24- to 30-h postprandial period were measured in seven growing pigs (36.1 +/- 2.3 kg) with catheters chronically placed in the hepatic portal vein, ileal vein, and carotid artery trained to consume 1.2 kg of a 16% CP corn soybean meal basal diet (B) once daily. The pigs were placed individually into an open-circuit, indirect calorimeter and connected to an arteriovenous (A-V) O2 difference analyzer for hourly simultaneous measurements of O2 consumption by W and PVDO. The PVDO O2 consumption was calculated by multiplying the A-V O2 difference by the portal vein blood flow rate derived from constant infusion of a p-aminohippuric acid solution into the ileal vein. After the initial series of hourly measurements, four pigs remained on the B diet and three pigs were fed a B + 55 ppm carbadox diet. Seven days later, the second series of measurements was made. In pigs fed the diet with carbadox added, the hourly W O2 consumptions were not different (P greater than .05) between the initial and second series and averaged 7.5 mL.min-1.kg of BW-1. However, the A-V O2 differences (mL/dL) were reduced (P less than .05) from 4.6 to 4.0 at 24 h, 4.8 to 4.0 at 25 h, and 4.6 to 4.0 at 29 h postprandial and the fractions of W O2 consumption used by PVDO (percentage) were reduced (P less than .05) from 28.6 to 21.6 at 26 h and 25.2 to 18.2 at 27 h postprandial.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen consumption by portal vein-drained organs and by whole animal in conscious growing swine.

A method was developed to measure simultaneously the O2 consumption (VO) by the whole animal and by the hepatic portal vein-drained organs (PVDO), including the gastrointestinal tract, spleen, and pancreas in conscious 3.5- to 4-month-old swine. The method was used to determine (i) the effect of feeding on hepatic portal vein blood flow rate (Qpv) and VO by PVDO and by the whole animal, and (ii) the significance of PVDO on the oxidative demand in the pig. Chronic cannulas were placed in the hepatic portal vein, carotid artery, and ileal vein. The Qpv was determined by an indicator dilution technique employing continuous constant infusion of 1% p-aminohippuric acid into the ileal vein. The VO2 by PVDO was estimated by multiplying Qpv by arterial-portal vein O2 difference measured with an arterial-venous O2 difference analyzer connected to the carotid artery and portal vein cannulas. Whole animal VO2 was measured with an open circuit indirect calorimeter. In seven pigs (3.5- to 4-month-old, 37.4 +/- 0.8 kg) trained to be fed once daily, feeding (1.2 kg of feed mixed with 1.2 liter of H2O) caused postprandial (6 hr) Qpv to increase more than 34 +/- 15% above the preprandial value of 34.5 +/- 4.2 ml.min-1.kg-1 body wt. The postprandial VO2 by PVDO was elevated more than 46 +/- 12% above the value of 1.52 +/- 0.20 ml.min-1.kg-1 body wt observed during the preprandial period. Whole animal VO2 increased 45 +/- 9 and 33 +/- 7% above the preprandial value of 6.23 +/- 0.57 ml.min-1.kg-1 body wt for the first 6 hr and the 7 to 12 hr after feeding, respectively. Although PVDO represent only 5% of body weight, they used 25% of whole body VO2. The study clearly illustrates the significance of PVDO on the whole animal oxidative demand in conscious growing swine.

A method for chronically quantifying net absorption of nutrients and gut metabolites into hepatic portal vein in conscious swine.

Surgical procedures are described for chronic cannulation of portal vein, ileal vein, abdominal aorta, and carotid artery in pigs. Silastic or Micro-Renathane tubing was used for cannulating portal vein and ileal vein, while carotid artery was cannulated with Micro-Renathane tubing. The lumen of Micro-Renathane tubing was coated with tri-dodecylmethyl ammonium chloride (TDMAC)-heparin complex. The abdominal aorta was cannulated via saphenous artery with vinyl tubing. This allows simultaneous collection of blood samples from hepatic portal vein and systemic artery (carotid or abdominal aorta) and continuous infusion of p-aminohippuric acid (PAH) into ileal vein. The constant PAH infusion provided an indicator-dilution method for estimating the blood flow rate in portal vein. In 13 pigs weighing 54 +/- 2.8 kg, the mean portal vein blood flow rate during the 8-h postprandial period was estimated to be 1,979 ml X min-1 X pig-1 or 37.8 ml X min-1 X kg-1 body weight. By simultaneously measuring the concentration of nutrients and metabolites in the portal and systemic arterial blood and multiplying porto-arterial differences by the estimated portal vein blood flow rate, the net absorption of nutrients (except long-chain fatty acids) and metabolites into hepatic portal system in conscious swine can be quantified.

Glucose Absorption and Hepatic Gluconeogenesis in Dairy Cows Fed Diets Varying in Forage Content

One dry and four lactating Holstein cows were prepared with chronic catheters in the mesenteric, hepatic and portal veins and used to study glucose absorption and hepatic gluconeogenesis. The dry cow was used in a preliminary assessment of the methods. In the main experiment high concentrate and high forage diets, providing equal energy intake, were delivered in hourly portions from an automatic feeder as total mixed rations. A few data were collected with the high concentrate ration fed ad libitum in early lactation. A few additional observations were made with limited feed intake by using the same cows subsequent to the main experiment. Portal and hepatic vein blood flow rates were determined by using para-aminohippuric acid. Glucose entry rates were significantly higher during ad libitum feeding of the high concentrate diet than during feeding of the two diets with restricted intake. There was no difference between high concentrate and high forage diets when fed at equal energy intakes. Net glucose appearance in portal blood was demonstrated. Data from this study and from the literature were used to develop general relationships between digestible energy intake and 1) portal vein blood flow, 2) rate of portal appearance of glucose and 3) total splanchnic glucose entry rate.

Effect of Caerulein upon Insulin and Glucagon Secretion in Dogs

In order to investigate the action of caerulein upon insulin and glucagon secretion, experimental studies were carried out using anesthetized dogs, in which graded doses of caerulein were infused into the pancreatic artery, and insulin and glucagon were measured in the blood obtained from the pancreatic vein. When caerulein was administered at a rate of 15 ng/min, neigher changes of blood glucose in the femoral artery nor plasma levels of insulin or glucagon in the pancreatic vein were prominent. Caerulein infusion at a rate of 120, 240 or 480 ng/min caused a prompt rise of plasma insulin and a delayed increase of plasma glucagon in the pancreatin vein. Blood glucose in the femoral artery increased only with caerulein doses of 240 ng/min or more. A significant increase in pancreatic vein blood flow rate was demonstrated after the infusion of caerulein at a rate of 240 ng/min or more. Neither caerulein-induced insulin secretion nor glucagon secretion was influenced by a simultaneous infusion of glucose. In contrast, caerulein-induced glucagon secretion was exaggreated by a simultaneous arginine infusion. It was concluded from the present experiments that caerulein infusion into the pancreatic artery resulted in increased secretion of insulin and glucagon from the pancreas.

Effects of maternal-fetal blood exchange transfusion in fetal lambs

An attempt to evaluate experimentally the effects of intrauterine fetal exchange transfusion on placental function is reported. In a series of acute experiments carried out on pregnant sheep and their fetal lambs, maternal-fetal cross transfusion, sufficient significantly to increase the content of maternal blood in the fetus, was successfully carried out. No significant changes in fetal oxygen consumption or umbilical vein blood flow rates were noted. Significant fetal acidosis and an increase in fetal blood PO2, with the ewe breathing either air or oxygen, were seen. The implications are discussed.