The Effect of Hematocrit on the Clearance of Small Molecules during Hemodialysis

1983 ◽  
Vol 6 (3) ◽  
pp. 127-130 ◽  
Author(s):  
C. Woffindin ◽  
N.A. Hoenich ◽  
D.N.S. Kerr
Keyword(s):  
Blood Flow ◽  
Regression Analysis ◽  
Small Molecules ◽  
Flat Plate ◽  
Flow Rate ◽  
Distribution Curve ◽  
Blood Flow Rate ◽  
Hollow Fibre ◽  
Urea Clearance ◽  
Flow Rates

Data collected during the evaluation of a series of hemodialysers were analysed to see the effect of hematocrit on the clearance of urea and creatinine. All evaluations were performed on patients with a range of hematocrits with a mean close to 20%. The urea clearance of those in the upper half of the distribution curve (mean hematocrit 29.4%) was not significantly different from that of patients in the lower half of the distribution curve (mean hematocrit 16.9%) whether the clearance was studied at high or low blood flow rates and with hollow fibre or flat plate disposable hemodialysers. Likewise, there was no correlation between hematocrit and urea clearance by regression analysis. In contrast, the clearance of creatinine was affected by hematocrit being greater at lower hematocrit values. This difference was independent of blood flow rate and dialyser type and was confirmed by regression analysis.

scholarly journals In vivo / in vitro Correlation of Pharmacokinetics of Gentamicin, Vancomycin, Teicoplanin and Doripenem in a Bovine Blood Hemodialysis Model

2021 ◽  
Vol 12 ◽  
Author(s):  
M G Vossen ◽  
S Pferschy ◽  
C Milacek ◽  
M Haidinger ◽  
Mario Karolyi ◽  
...  
Keyword(s):  
Blood Flow ◽  
Renal Replacement Therapy ◽  
Protein Binding ◽  
Replacement Therapy ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Bovine Blood ◽  
Flow Rates ◽  
Dialysate Flow Rate

Background: Elimination of a drug during renal replacement therapy is not only dependent on flow rates, molecular size and protein binding, but is often influenced by difficult to predict drug membrane interactions. In vitro models allow for extensive profiling of drug clearance using a wide array of hemofilters and flow rates. We present a bovine blood based in vitro pharmacokinetic model for intermittent renal replacement therapy.Methods: Four different drugs were analyzed: gentamicin, doripenem, vancomicin and teicoplanin. The investigated drug was added to a bovine blood reservoir connected to a hemodialysis circuit. In total seven hemofilter models were analyzed using commonly employed flow rates. Pre-filter, post-filter and dialysate samples were drawn, plasmaseparated and analyzed using turbidimetric assays or HPLC. Protein binding of doripenem and vancomycin was measured in bovine plasma and compared to previously published values for human plasma.Results: Clearance values were heavily impacted by choice of membrane material and surface as well as by dialysis parameters such as blood flow rate. Gentamicin clearance ranged from a minimum of 90.12 ml/min in a Baxter CAHP-170 diacetate hemofilter up to a maximum of 187.90 ml/min in a Fresenius medical company Fx80 polysulfone model (blood flow rate 400 ml/min, dialysate flow rate 800 ml/min). Clearance of Gentamicin vs Vancomicin over the F80s hemofilter model using the same flow rates was 137.62 mL vs 103.25 ml/min. Doripenem clearance with the Fx80 was 141.25 ml/min.Conclusion: Clearance values corresponded very well to previously published data from clinical pharmacokinetic trials. In conjunction with in silico pharmacometric models. This model will allow precise dosing recommendations without the need of large scale clinical trials.

Blood Flow Rate and Access Recirculation in Hemodialysis

1992 ◽  
Vol 15 (8) ◽  
pp. 470-474 ◽  
Author(s):  
I.D. Daniels ◽  
G.M. Berlyne ◽  
R.H. Barth
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Hemodialysis Patients ◽  
Blood Pump ◽  
Concomitant Increase ◽  
Urea Clearance ◽  
Extracorporeal Blood

We studied the effect of extracorporeal blood flow rate (BFR) on access recirculation (recirc) in 19 hemodialysis patients. BUN was determined in simultaneous peripheral (P), arterial (A), and venous (V) blood obtained at BFRs of 200, 400 and 600 ml/min. Percent recirc was calculated for each BFR using the formula (P-A) / (P-V) X 100. Venous drip-chamber (VP) and pre-blood-pump (AP) pressures were measured at each BFR. Fistulograms were performed in 10 patients, and stenoses were identified in 5, all at the proximal (arterial) end of the access. Recirc increased with increasing BFR from 200 to 400 ml/min but increased little from 400 to 600 ml/min. At all BFRs recirc in the stenotic patients was higher than that of non-stenotic or unstudied patients. Urea clearance, corrected for recirc, rose with blood flow both in stenotic and non-stenotic patients. There were no differences in AP or in VP between stenotic and non-stenotic patients. At BFR ≥ 400 ml/min, a recirc threshold of 15% identified stenoses with sensitivity 100% and specificity 71%. We conclude (1) recirc increases with increasing BFR but not enough to outweight the concomitant increase in urea clearance; (2) significant access stenosis and recirc may be present even with low VP; (3) recirc was associated with arterial side stenoses; (4) at BFR ≥ 400 ml/min, access stenosis is associated with recirc > 15%.

Sensitivity of patient-specific numerical simulation of cerebal aneurysm hemodynamics to inflow boundary conditions

2007 ◽  
Vol 106 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Prem Venugopal ◽  
Daniel Valentino ◽  
Holger Schmitt ◽  
J. Pablo Villablanca ◽  
Fernando Viñuela ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Flow Rate ◽  
Artery Aneurysm ◽  
Blood Flow Rate ◽  
Patient Specific ◽  
Stress Distributions ◽  
Flow Rates

Object Due to the difficulty of obtaining patient-specific velocity measurements during imaging, many assumptions have to be made while imposing inflow boundary conditions in numerical simulations conducted using patient-specific, imaging-based cerebral aneurysm models. These assumptions can introduce errors, resulting in lack of agreement between the computed flow fields and the true blood flow in the patient. The purpose of this study is to evaluate the effect of the assumptions made while imposing inflow boundary conditions on aneurysmal hemodynamics. Methods A patient-based anterior communicating artery aneurysm model was selected for this study. The effects of various inflow parameters on numerical simulations conducted using this model were then investigated by varying these parameters over ranges reported in the literature. Specifically, we investigated the effects of heart and blood flow rates as well as the distribution of flow rates in the A1 segments of the anterior cerebral artery. The simulations revealed that the shear stress distributions on the aneurysm surface were largely unaffected by changes in heart rate except at locations where the shear stress magnitudes were small. On the other hand, the shear stress distributions were found to be sensitive to the ratio of the flow rates in the feeding arteries as well as to variations in the blood flow rate. Conclusions Measurement of the blood flow rate as well as the distribution of the flow rates in the patient's feeding arteries may be needed for numerical simulations to accurately reproduce the intraaneurysmal hemodynamics in a specific aneurysm in the clinical setting.

High Blood flow Rates with Adjustment of Needle Diameter do not Increase Hemolysis during Hemodialysis Treatment

2007 ◽  
Vol 8 (4) ◽  
pp. 252-257 ◽  
Author(s):  
F. Techert ◽  
S. Techert ◽  
L. Woo ◽  
W. Beck ◽  
H. Lebsanft ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Venous Pressure ◽  
Blood Flow Rate ◽  
Needle Size ◽  
Flow Rates ◽  
Blood Damage ◽  
Before And After ◽  
Needle Diameter ◽  
Hb Concentration

Background Higher blood flow in dialysis therapy is often avoided due to concerns about shear-induced blood damage despite the lack of reliable data. Objective This study investigated the influence of higher blood flow rates on plasma free hemoglobin (Hb) concentration after hemodialysis (HD) treatment. Methods Thirty-two chronic HD patients were treated once with a blood flow rate of 250 mL/min using a 17G needle, and once with a blood flow rate of 500 mL/min using a 14G needle. Arterial and venous pressure and blood pressure (BP) were recorded before and after treatment. Blood samples were taken before and after treatment for analysis of plasma free Hb, pH, HCO3, base excess, hematocrit value, urea, sodium, potassium and calcium. Results HD treatment at blood flow rates of 500 mL/min did not increase plasma free Hb compared to treatments at blood flow rates of 250 mL/min. Frequency of intradialytic BP drops was not different either. By adaptation of the needle size, negative arterial pressure could be kept at a similar level. Urea reduction rates were significantly higher during treatments with higher blood flow rates. Conclusion Higher blood flow rates can be applied without an increased hemolysis risk provided that needle sizes are adapted accordingly.

Effect of blood flow rate and blood flow history on newborn pulmonary microcirculation

1991 ◽  
Vol 261 (2) ◽  
pp. H271-H279 ◽  
Author(s):  
C. D. Fike ◽  
M. R. Kaplowitz
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Left Atrial ◽  
Total Pressure ◽  
Pulmonary Blood Flow ◽  
Blood Flow Rate ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Flow Rates ◽  
Pulmonary Arterial

The purpose of this study was to determine whether increased pulmonary blood flow and/or the history of pulmonary blood flow alters microvascular pressures in lungs of newborns. Using the direct micropuncture technique, we measured pressures in 20- to 60-microns-diameter arterioles and venules in isolated lungs of newborn rabbits at consecutive blood flow rates of 50 (baseline), 100, and/or 200 ml.min-1.kg-1. Then in some lungs we returned blood flow rate to baseline and repeated microvascular pressure measurements. We kept left atrial pressure the same at all blood flow rates. When blood flow rate increased and left atrial pressure was maintained constant, pulmonary arterial, 20- to 60-microns-diameter arteriolar, and 20- to 60-microns-diameter venular pressures increased such that the percentage of total pressure drop that occurred across veins increased. When we returned blood flow to baseline, venular pressure returned to baseline, but arteriolar and pulmonary arterial pressures returned to values less than baseline so that the percentage of the total pressure drop that occurred across microvessels decreased. Thus both blood flow rate and blood flow history are important determinants of the longitudinal distribution of pulmonary vascular pressures across newborn lungs. These findings also suggest that in newborn lungs venules greater than 60 microns diameter are poorly distensible such that higher blood flow rates result in increased microvascular pressures. Hence, under conditions of increased pulmonary blood flow, such as occurs with left to right shunts, the tendency for edema formation will increase in newborn lungs even if left atrial pressure does not increase.

scholarly journals P1423INCREASED BLOOD FLOW RATE IN HIGH-FLUX HAEMODIALYSIS - IS IT RELEVANT FOR PHOSPHORUS REMOVAL IN HAEMODIALYSIS PATIENTS?

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Nikolina Smokovska ◽  
Olivera Stojceva-Taneva ◽  
Mence Nedelkoska ◽  
Nadica Misovska ◽  
Nikola Josimovski ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Function ◽  
Patient Group ◽  
Flow Rate ◽  
Phosphorus Removal ◽  
Blood Flow Rate ◽  
Phosphate Binders ◽  
Average Dose ◽  
High Flux ◽  
Urea Clearance

Abstract Background and Aims High-flux haemodialysis (HD), beside other uremic solutes harmful for patients, controls the level of phosphorus, major factor for HD-related morbidity and mortality. First line in phosphorus control in HD patients is dietary phosphorus intake reduction, whereas its’ removal is undervalued by hemodialysis. The primary objective was to analyse whether change in the rate of blood flow is relevant in phosphorus removal in HD patients. Second objective was to evaluate other variables impacted by higher blood flow rates. Method Retrospective study was conducted enrolling 80 patients from a single center in a period of 12 months. In the first six months, all patients were on lower blood flow rate (LBFR group) than the same patient group was switched to a higher blood flow rate in the following six months (HBFR group). Demographic, clinical and laboratory variables were collected and intra/inter-patient group analysis was performed. Results Forty-seven patients were male, and 41.3% were female. Mean age of the study population was 61.2±13.47 years (males 60.3±13.38, females 62.4±13.68). Mean dialysis vintage was 63.31±66.57 months. The average real blood flow rate in LBFR group was 290.75±19.65 ml/min (median 285.34 ml/min), 344.87±9.12 ml/min in HBFR group (median 339 ml/min), p=0.0002. The level of phosphorus in LBFR group was 1.52±0.03 mmol/L, and 1.45±0.04 in HBFR group, p=0.007. Other variables that significantly showed improvement following the increase of blood flow rate were eKT/V (p=0.0006), urea clearance (p=0.02) and transferrin saturation (p=0.04). The level of post-HD urea (p=0.02) and body surface area (p=0.04) were decreased. Weekly EPO dosage decrease in HBFR group (p=0.02) was not correlated with increased iron sucrose administration (LBFR group 59.99±36.18 mg/wk, HBFR group 65.8±28.7, p=0.45). There were no significant changes related to cardiac function; systolic (p=0.44) and diastolic pressure (p=0.36), mean arterial (p=0.43) and pulse pressure (p=0.26) remained in reference range. Also, the average dose of calcium-based phosphate binders did not change significantly (p=0.34). Conclusion This study showed that increased blood flow rate in HD patients reduces phosphorus and EPO consumption, improves urea clearance without significant impact on cardiac function and calcium overload with calcium-based phosphate binders.

Preglomerular resistance and glomerular perfusion in the rat and dog

1976 ◽  
Vol 231 (3) ◽  
pp. 961-966 ◽  
Author(s):  
WR Chenitz ◽  
BA Nevins ◽  
NK Hollenberg
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Radioactive Microspheres ◽  
Flow Rates ◽  
Afferent Arterioles ◽  
The Difference ◽  
Inner Cortex ◽  
Fractional Distribution

Glomerular blood flow in the rat, measured with radioactive microspheres, averaged 233 +/- 59 nl/min per glomerulus, significantly less than the glomerular flow rate in the dog (568 +/- 115; P less than 0.005). The difference in glomerular blood flow rate could not be attributed to differences in mean or cortical flow rates, the fraction of acrdiac output received, cardiac output normalized to body weight, or the fractional distribution of blood flow or glomeruli from outer to inner cortex in the two species. The size of microspheres reaching the glomerulus, however, was significantly larger in the dog than in the rat (P less than 0.0005) suggesting that afferent arterioles were larger in the dog than rat. The difference in afferent resistance calculated from the size of microspheres delivered to the glomeruli was larger than the difference in glomerular blood flow. With a similar arterial pressure, a lower afferent resistance suggests a higher glomerular capillary pressure in the dog, consistent with a number of suggestions that filtration equilibrium is less likely in this species.

scholarly journals Detection of Microembolic Signals in the Common Carotid Artery Using Doppler Sonography in the Porcine Model of Acute Heart Failure Treated by Veno-Arterial Extracorporeal Membrane Oxygenation

2017 ◽  
pp. S529-S536 ◽  
Author(s):  
D. JANÁK ◽  
P. HÁLA ◽  
M. MLČEK ◽  
M. POPKOVÁ ◽  
S. LACKO ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Flow ◽  
Carotid Artery ◽  
Extracorporeal Membrane Oxygenation ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Flow Rates ◽  
The Common ◽  
Va Ecmo ◽  
Ecmo Flow

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a method used for the treatment most severe cases of decompensated heart failure. The purpose of this study was to evaluate the risk of the formation of microembolisms during VA-ECMO-based therapy. Heart failure was induced with simultaneous detection of microembolisms and the measurement of blood flow rate in the common carotid artery (CCA) without VA-ECMO (0 l/min) and at the VA-ECMO blood flow rate of 1, 2, 3 and 4 l/min. If embolisms for VA-ECMO 0 l/min and the individual regimes for VA-ECMO 1, 2, 3, 4 l/min are compared, a higher VA-ECMO flow rate is accompanied by a higher number of microembolisms. The final microembolism value at 16 min was for the VA-ECMO flow rate of 0 l/min 0.0 (0, 1), VA-ECMO l/min 7.5 (4, 19), VA-ECMO 2 l/min 12.5 (4, 26), VA-ECMO 3 l/min, 21.0 (18, 57) and VA-ECMO 4 l/min, 27.5 (21, 64). Such a comparison is statistically significant if VA-ECMO 0 vs. 4 l/min p<0.0001, 0 vs. 3 l/min p<0.01 and 1 vs. 4 l/min p<0.01 are compared. The results confirm that high VA-ECMO flow rates pose a risk with regards to the formation of a significantly higher number of microemboli in the blood circulation and that an increase in blood flow rates in the CCA corresponds to changes in the VA-ECMO flow rates.

Suprarenal Fixation: Effect on Blood Flow of an Endoluminal Stent Wire across an Arterial Orifice

2003 ◽  
Vol 10 (2) ◽  
pp. 260-274 ◽  
Author(s):  
Kurt Liffman ◽  
Michael M.D. Lawrence-Brown ◽  
James B. Semmens ◽  
Ilija D. Šutalo ◽  
Anh Bui ◽  
...  
Keyword(s):  
Blood Flow ◽  
Renal Artery ◽  
Flow Rate ◽  
Analytical Methods ◽  
Volume Flow Rate ◽  
Blood Flow Rate ◽  
Flow Rates ◽  
Fixation Effect ◽  
The Wire ◽  
Numerical And Analytical Methods

Purpose: To investigate what effect, if any, the presence of a stent wire in front of a renal artery has on the volume flow rate of blood through the renal artery. Methods: Experimental, numerical, and analytical modeling methods were used to test 4 separate stent wire configurations: a stent wire across the center of an artery orifice, an off-center wire placed at one-quarter the arterial diameter, a V-shaped wire with its vertex at the center, and 2 stent wires at one-third-diameter spacing. Results: For all the configurations studied, the presence of stent wires has a minimal effect on the blood flow rate into an artery of ≥3-mm diameter, with most flow rates decreasing by around 1%. This is true provided that there is no buildup of material on the wire. When material buildup was “encouraged” to occur, then decreases in flow rate of up to 40% were observed. The numerical and analytical methods indicated that the flow rates would, in most cases, decrease by around 3% to 10%. Conclusions: A bare stent wire in front of a >3-mm-diameter artery decreases the flow rate minimally, providing there is no material on the wire. Although the numerical and analytical methods indicated a greater effect on flow, the approximations required for these 2 methods to obtain meaningful solutions suggest that the experimental results are the most accurate. Nonetheless, the analytical equations provided a useful approximation for determining the effect on blood flow due to the presence of a stent wire.

Sign in / Sign up

Export Citation Format

Share Document