Reference values for resting blood flow to organs of man

Williams, Larry R.; Leggett, Richard W.

doi:10.1088/0143-0815/10/3/001

Cited by 313 publications

(182 citation statements)

References 203 publications

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“…Blood flow rates as percentage of cardiac output are given in the ICRP report (ICRP 2003) for the resting middle-aged male adult, based on a compilation of published data by Williams and Leggett (1989) and Leggett and Williams (1995). These data were used to calculate blood flow rates (L/h) for liver (arterial and portal flow), brain, kidney, adipose tissue (fat), muscle/skin and skeleton (without active bone marrow).…”

Section: Blood Flow To Organs and Tissuesmentioning

confidence: 99%

Elevated internal exposure of children in simulated acute inhalation of volatile organic compounds: effects of concentration and duration

et al. 2004

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When deriving health based exposure limits in recent years, attention has been drawn to susceptible subpopulations, in particular to children. We investigate the differences in kinetics between children and adults during inhalation of styrene as a typical category 3 volatile organic compound (VOC), i.e. a gas with a high rate of alveolar absorption (due to low reactivity and low water solubility). Internal exposure was simulated using a physiologically based kinetic model over a broad range of airborne concentrations (1 to 1000 ppm) and for an exposure time of up to eight hours according to the scenario in the acute exposure guideline level (AEGL) program. Age-specific anatomical and physiological parameters and compound-specific data were derived from the literature. The calculated concentrations in arterial blood are higher in children than in adults, and are highest in the newborn. For an 8-hour exposure to low concentrations, the calculated arterial concentration in the newborn is higher by a factor of 2.3 than in the adult. This is mainly due to the relatively high ventilation rate and the immature metabolism. With increasing airborne concentration, the ratio of arterial concentrations (newborn/adult) increases to a maximum of 3.8 at 130 ppm in ambient air, and declines with further increments of concentration to a value of 1.7. This is because the metabolism of the newborn becomes non-linear at lower concentrations than in adults. At high concentrations, metabolism is saturated in both age groups. For shorter exposures, the dose-dependency of the concentration ratios (newborn/adult) is less pronounced. This is the first article to show that the intraspecies uncertainty factor may vary with concentration and duration of exposure.

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Section: Blood Flow To Organs and Tissuesmentioning

confidence: 99%

Elevated internal exposure of children in simulated acute inhalation of volatile organic compounds: effects of concentration and duration

et al. 2004

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“…Particularly, the right adrenal vein often enters the inferior vena cava (IVC) in a steep angle impeding cannulation. Furthermore, adrenal blood flow is estimated to be w0.2% of cardiac output (8), which leads to a considerable admixture of blood drawn back from the IVC or the renal vein as well as admixture of blood from accessory hepatic or subphrenic veins. Thus, aldosterone concentrations may vary considerably depending on the exact position of the catheter tip in relation to the orifice of the adrenal vein (9).…”

Section: Introductionmentioning

confidence: 99%

Adrenal vein sampling using rapid cortisol assays in primary aldosteronism is useful in centers with low success rates

Betz

Degenhart

Fischer

et al. 2011

European Journal of Endocrinology

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Objective: Adrenal vein sampling (AVS) is considered the gold standard in the differential diagnosis of primary aldosteronism (PA), but success rates vary between centers. We hypothesized that rapid (intraprocedure) cortisol measurement can improve performance in a center with initially low AVS success rate. Design: We analyzed 46 patients with confirmed PA studied between 2008 and 2010. Forty-seven PA patients studied between 2004 and 2008 identified by retrospective chart review served as controls. All patients were treated at a single tertiary care university hospital. Methods: Starting in 2008, rapid cortisol assays (RCA) were performed in all patients during the AVS procedure. A cortisol gradient of R2.0 between adrenal vein and a femoral vein sample was used as success criterion. Up to two repeat samples were drawn if adrenal vein cortisol was below this threshold. Results: During the control period 26 of 47 AVS were successful (55%). After introduction of RCA, 39 out of 46 AVS (85%) were successful (PZ0.003). In 21 of the 46 cases (46%) a resampling was necessary. The increase in overall success was due to an increase in successful right AVS (85 vs 62% before introduction of RCA; PZ0.02) and a training effect (PZ0.024 for trend). Conclusion: RCA during AVS are useful in centers with an initially low AVS success rate.

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“…The latter parameter was defined the sum of the arterial blood supply to the liver and the non-villous portal blood flow (i.e. oesophagus, stomach, gut tissue, pancreas, upper large intestine, lower large intestine and spleen) (37)(38)(39). Given that the observed clinical data is usually reported as plasma concentrations rather than blood concentrations, the concentration represented by Eq.…”

Section: Development Of Oxy's Disposition Modelmentioning

confidence: 99%

Development of a Novel Simplified PBPK Absorption Model to Explain the Higher Relative Bioavailability of the OROS® Formulation of Oxybutynin

Olivares‐Morales

Ghosh

Aarons

et al. 2016

AAPS J

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Abstract.A new minimal Segmented Transit and Absorption model (mSAT) model has been recently proposed and combined with intrinsic intestinal effective permeability (P eff,int ) to predict the regional gastrointestinal (GI) absorption (f abs ) of several drugs. Herein, this model was extended and applied for the prediction of oral bioavailability and pharmacokinetics of oxybutynin and its enantiomers to provide a mechanistic explanation of the higher relative bioavailability observed for oxybutynin's modified-release OROS® formulation compared to its immediate-release (IR) counterpart. The expansion of the model involved the incorporation of mechanistic equations for the prediction of release, transit, dissolution, permeation and first-pass metabolism. The predicted pharmacokinetics of oxybutynin enantiomers after oral administration for both the IR and OROS® formulations were in close agreement with the observed data. The predicted absolute bioavailability for the IR formulation was within 5% of the observed value, and the model adequately predicted the higher relative bioavailability observed for the OROS® formulation vs. the IR counterpart. From the model predictions, it can be noticed that the higher bioavailability observed for the OROS® formulation was mainly attributable to differences in the intestinal availability (F G ) rather than due to a higher colonic f abs , thus confirming previous hypotheses. The predicted f abs was almost 70% lower for the OROS® formulation compared to the IR formulation, whereas the F G was almost eightfold higher than in the IR formulation. These results provide further support to the hypothesis of an increased F G as the main factor responsible for the higher bioavailability of oxybutynin's OROS® formulation vs. the IR.

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Reference values for resting blood flow to organs of man

Cited by 313 publications

References 203 publications

Elevated internal exposure of children in simulated acute inhalation of volatile organic compounds: effects of concentration and duration

Elevated internal exposure of children in simulated acute inhalation of volatile organic compounds: effects of concentration and duration

Adrenal vein sampling using rapid cortisol assays in primary aldosteronism is useful in centers with low success rates

Development of a Novel Simplified PBPK Absorption Model to Explain the Higher Relative Bioavailability of the OROS® Formulation of Oxybutynin

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