Article

# Specific Gravity of Blood and Plasma at 4 and 37 °C

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## Abstract

The specific gravity (relative density) of human whole blood and plasma from 25 healthy volunteers was determined gravimetrically. For whole blood it was found to be 1.0621 (95% confidence interval: 1.0652-1.0590) at 4°C and 1.0506 (95% confidence interval: 1.0537-1.0475) at 37°C. Plasma specific gravity was 1.0310 (95% confidence interval: 1.0324-1.0296) at 4°C and 1.0205 (95% confidence interval: 1.0216-1.0193) at 37°C. All of these values are referred to the density of water at 4°C. The relationship is shown between these values and those given in the literature for measurements at 25°C. There was a small increase in whole blood specific gravity with increasing hematocrit, but it was not statistically significant over the 40-56 hematocrit range studied.

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... All other metal measurements were above the LOD for each metal. The conversion of blood manganese levels from ng/g to µg/L was performed using 1.0506 as the specific density of a typical whole blood sample at 37 • C (Trudnowski et al., 1974). ...
... These levels correspond to 16.0 (13.1-19.4) µg/L, on using 1.0506 as the specific gravity of a typical whole blood sample at 37 • C (Trudnowski et al., 1974). There were no differences in median and IQR of maternal and cord blood Mn levels between the whole group and the subgroup. ...
Article
Background Manganese (Mn) is an essential trace metal and a neurotoxicant. Adverse effects of Mn exposure on the neurodevelopment of children have been reported. However, there is limited information on the effects of maternal exposure during pregnancy. Objectives We aimed to investigate the association between maternal and cord blood Mn levels and neurodevelopment in children aged between 6 months and 3 years using data from a Japanese nationwide birth cohort study. Methods We used the data of 63,767 mother–child pairs with maternal blood Mn measurements recorded during the second and third trimester and of 3,787 mother–child pairs with cord blood Mn measurements. Neurodevelopment was assessed using the Japanese version of the Ages and Stages Questionnaires, third edition (J-ASQ-3), which was completed by parents or guardians at 6 months, 1 year, 1.5 years, 2 years, 2.5 years, and 3 years of age. Results The median maternal and cord blood Mn levels were 15.2 and 44.5 ng/g, respectively. After adjusting for covariates, both maternal and cord blood Mn levels were negatively associated with J-ASQ-3 scores. Maternal blood Mn levels were negatively associated with gross motor function scores at all ages except for that at 1.5 years (adjusted β: −0.55 to −1.23 for a two-fold increase in maternal Mn levels). The risk of developmental delay (score below the cut-off) in gross motor function increased at the same time points (adjusted odds ratio: 1.08 to 1.13). In the subgroup, cord blood Mn levels were negatively associated with gross motor function scores at 1, 2, and 2.5 years (adjusted β: −1.84 to −3.27). Discussion Maternal blood Mn levels during pregnancy and cord blood Mn levels were negatively associated with neurodevelopment in children up to 3 years of age. Excessive maternal and fetal exposure to Mn may have adverse effects on neuromotor function in children.
... 4 The mass densities of water and whole blood are 1000 kg/m 3 and 1060 kg/m 3 , respectively. 28,29 The mass density of air is 1.2 kg/m 3 , and the gravity is 9.81 m/s 2 . The fluid depth d is assumed to be 3 mm. ...
... 4 The mass densities of water and whole blood are 1000 kg/m 3 and 1060 kg/m 3 , respectively. 28,29 The mass density of air is 1.2 kg/m 3 and gravity is 9.81 m/s 2 . The fluid depth d is assumed to ARTICLE scitation.org/journal/adv ...
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The surface tension of biological fluids is an important parameter because the mechanical properties of fluids are closely linked with hematological diseases and other pathophysiologies. Capillary waves are associated with fluid mechanical properties. Here, we propose a method that utilizes the acoustic radiation force (ARF) to generate propagating waves and optical coherence tomography (OCT) to measure the wave motion. This ARF-OCT method is capable of evaluating the surface tension of fluids, water and porcine whole blood in this study, based on the dispersion relation of capillary waves. Two-dimensional Fourier transforms were used to decompose frequency components of wave motion images to obtain a k-space representation and estimate the wave phase velocity. The phase velocity of capillary waves was obtained from the experimental results and compared to theoretical calculations. The surface tensions of water and porcine whole blood were determined from the experimental results. We first report that capillary waves measured with OCT can be a new promising modality for measuring the surface tension of fluids. The proposed method could be used to differentiate actual pathologic fluids or blood from those taken from healthy subjects and as a biomarker in future biomedical applications.
... Irrigation fluid was similarly recorded. The weight of surgical swabs was converted to volume (specific gravity of blood 1⋅0506 30 ). In addition, the volume of ascites, bile loss and other unmeasurable fluids was estimated using the surgeon's best judgement. ...
Article
Background: Major liver resection is associated with blood loss and transfusion. Observational data suggest that hypovolaemic phlebotomy can reduce these risks. This feasibility RCT compared hypovolaemic phlebotomy with the standard of care, to inform a future multicentre trial. Methods: Patients undergoing major liver resections were enrolled between June 2016 and January 2018. Randomization was done during surgery and the surgeons were blinded to the group allocation. For hypovolaemic phlebotomy, 7-10 ml per kg whole blood was removed, without intravenous fluid replacement. Co-primary outcomes were feasibility and estimated blood loss (EBL). Results: A total of 62 patients were randomized to hypovolaemic phlebotomy (31) or standard care (31), at a rate of 3·1 patients per month, thus meeting the co-primary feasibility endpoint. The median EBL difference was -111 ml (P = 0·456). Among patients at high risk of transfusion, the median EBL difference was -448 ml (P = 0·069). Secondary feasibility endpoints were met: enrolment, blinding and target phlebotomy (mean(s.d.) 7·6(1·9) ml per kg). Blinded surgeons perceived that parenchymal resection was easier with hypovolaemic phlebotomy than standard care (16 of 31 versus 10 of 31 respectively), and guessed that hypovolaemic phlebotomy was being used with an accuracy of 65 per cent (20 of 31). There was no significant difference in overall complications (10 of 31 versus 15 of 31 patients), major complications or transfusion. Among those at high risk, transfusion was required in two of 15 versus three of nine patients (P = 0·326). Conclusion: Endpoints were met successfully, but no difference in EBL was found in this feasibility study. A multicentre trial (PRICE-2) powered to identify a difference in perioperative blood transfusion is justified. Registration number: NCT02548910 ( http://www.clinicaltrials.gov).
... To directly compare plasma and tissue concentrations, we assumed a specific density of 1.03 g/mL for plasma. 20 An amount of 0.1 g deep frozen tissue was homogenized under constant cooling with 0.9 mL 70% acetonitrile; 0.1 mL of this homogenate was diluted with 0.9 mL 70% acetonitrile. For calibration, a 0.3 g propofol-free deep-frozen sample of the respective tissue was homogenized under constant cooling with 2.7 mL 70% acetonitrile. ...
Article
Background: Propofol can be measured in exhaled gas. Exhaled and plasma propofol concentrations correlate well, but the relationship with tissue concentrations remains unknown. We thus evaluated the relationship between exhaled, plasma, and various tissue propofol concentrations. Because the drug acts in the brain, we focused on the relationship between exhaled and brain tissue propofol concentrations. Methods: Thirty-six male Sprague-Dawley rats were anesthetized with propofol, ketamine, and rocuronium for 6 hours. Animals were randomly assigned to propofol infusions at 20, 40, or 60 mg·kg·h (n = 12 per group). Exhaled propofol concentrations were measured at 15-minute intervals by multicapillary column-ion mobility spectrometry. Arterial blood samples, 110 µL each, were collected 15, 30, and 45 minutes, and 1, 2, 4, and 6 hours after the propofol infusion started. Propofol concentrations were measured in brain, lung, liver, kidney, muscle, and fat tissue after 6 hours. The last exhaled and plasma concentrations were used for linear regression analyses with tissue concentrations. Results: The correlation of exhaled versus plasma concentrations (R = 0.71) was comparable to the correlation of exhaled versus brain tissue concentrations (R = 0.75) at the end of the study. In contrast, correlations between plasma and lung and between lung and exhaled propofol concentrations were poor. Less than a part-per-thousand of propofol was exhaled over 6 hours. Conclusions: Exhaled propofol concentrations correlate reasonably well with brain tissue and plasma concentrations in rats, and may thus be useful to estimate anesthetic drug effect. The equilibration between plasma propofol and exhaled gas is apparently independent of lung tissue concentration. Only a tiny fraction of administered propofol is eliminated via the lungs, and exhaled quantities thus have negligible influence on plasma concentrations.
... We set C d = 0.74 (unitless) and ρ = 1.05 g/cm 3 as reported previously. 17,18 Once we have determined S L , S R , and V T , we can predict IAS haemodynamics by simultaneously solving these seven equations. Details of the calculation are given in the Supporting Information. ...
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Aims: Interatrial shunting (IAS) reduces left atrial pressure in patients with heart failure. Several clinical trials reported that IAS improved the New York Heart Association score and exercise capacity. However, its effects on haemodynamics vary depending on shunt size, cardiovascular properties, and stressed blood volume. To maximize the benefit of IAS, quantitative prediction of haemodynamics under IAS in individual patients is essential. The generalized circulatory equilibrium framework determines circulatory equilibrium as the intersection of the cardiac output curve and the venous return surface. By incorporating IAS into the framework, we predict the impact of IAS on haemodynamics. Methods and results: In seven mongrel dogs, we ligated the left anterior descending artery and created impaired cardiac function with elevated left atrial pressure (baseline: 7.8 ± 1.0 vs. impaired: 11.9 ± 3.2 mmHg). We established extracorporeal left-to-right atrial shunting with a centrifugal pump. After recording pre-IAS haemodynamics, we changed IAS flow stepwise to various levels and measured haemodynamics under IAS. To predict the impact of IAS on haemodynamics, we modelled the fluid mechanics of IAS by Newton's second law and incorporated IAS into the generalized circulatory equilibrium framework. Using pre-IAS haemodynamic data obtained from the dogs, we predicted the impact of IAS flow on haemodynamics under IAS condition using a set of equations. We compared the predicted haemodynamic data with those measured. The predicted pulmonary flow [r2 = 0.88, root mean squared error (RMSE) 11.4 mL/min/kg, P < 0.001), systemic flow (r2 = 0.92, RMSE 11.2 mL/min/kg, P < 0.001), right atrial pressure (r2 = 0.92, RMSE 0.71 mmHg, P < 0.001), and left atrial pressure (r2 = 0.83, RMSE 0.95 mmHg, P < 0.001) matched well with those measured under normal and impaired cardiac function. Using this framework, we further performed a simulation study to examine the haemodynamic benefit of IAS in heart failure with preserved ejection fraction. We simulated the IAS haemodynamics under volume loading and exercise conditions. Volume loading and exercise markedly increased left atrial pressure. IAS size-dependently attenuated the increase in left atrial pressure in both volume loading and exercise. These results indicate that IAS improves volume and exercise intolerance. Conclusions: The framework developed in this study quantitatively predicts the haemodynamic impact of IAS. Simulation study elucidates how IAS improve haemodynamics under volume loading and exercise conditions. Quantitative prediction of IAS haemodynamics would contribute to maximizing the benefit of IAS in patients with heart failure.
... h is the height of the level of the heart above the ground (0.6 m), g is the acceleration acting on the participant inside the centrifuge gondola resulting from 3g centrifugal acceleration and 1g Earth gravity (3.16g), and ρ is the density of the blood (1.0621 g/cm 3 ). 12 Participants were placed in sitting position in a fully closed swing-out cabin attached to the 5 m long centrifuge arm ( Figure 1A). During centrifugation, the G-load acted strictly caudally. ...
Article
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Background Hypergravity may promote human hemostasis thereby increasing thrombotic risk. Future touristic suborbital spaceflight will expose older individuals with chronic medical conditions, who are at much higher thromboembolic risk compared with professional astronauts, to hypergravity. Therefore, we tested the impact of hypergravity on hemostasis in healthy volunteers undergoing centrifugation. Methods and Results We studied 20 healthy seated men before and after 15 minutes under 3 Gz hypergravity on a long‐arm centrifuge. We obtained blood samples for hemostasis testing before, immediately after, and 30 minutes after centrifugation. Tests included viscoelastic thromboelastometry, platelet impedance aggregometry, endothelial activation markers, blood rheology testing, microparticle analyses, and clotting factor analysis. Exposure to hypergravity reduced plasma volume by 12.5% ( P =0.002) and increased the red blood cell aggregation index ( P <0.05). With hypergravity, thrombelastographic clotting time of native blood shortened from 719±117 seconds to 628±89 seconds ( P =0.038) and platetet reactivity increased ( P =0.045). Hypergravity shortened partial thromboplastin time from 28 (26–29) seconds to 25 (24–28) seconds ( P <0.001) and increased the activity of coagulation factors (eg, factor VIII 117 [93–134] versus 151 [133–175] %, P <0.001). Tissue factor concentration was 188±95 pg/mL before and 298±136 pg/mL after hypergravity exposure ( P =0.023). Antithrombin ( P =0.005), thrombin‐antithrombin complex ( P <0.001), plasmin‐alpha2‐antiplasmin complex (0.002), tissue‐plasminogen activatior ( P <0.001), and plasminogen activator inhibitor‐1 ( P =0.002) increased with centrifugation. Statistical adjustment for plasma volume attenuated changes in coagulation. Conclusions Hypergravity triggers low‐level hemostasis activation through endothelial cell activation, increased viscoelasticity, and augmented platelet reactivity, albeit partly counteracted through endogenous coagulation inhibitors release. Hemoconcentration may contribute to the response.
... Currently, most research that has validated mammalian blood sources for forensic purposes has focused on whole porcine, whole ovine and defibrinated equine blood with and without anticoagulants [2][3][4][5][6]. Importantly, Williams [7], Sparer et al. [4] and de Castro et al. [5] showed that porcine blood with an added dextrose-based anticoagulant is suitable for use through fluid characterization and comparison to reported human values [2,[8][9][10][11][12][13][14][15][16][17][18][19]. The addition of anticoagulant to the blood source is important for storability and shelf life of the fluid; and particular attention should be held on volume optimization as ineffective ratios of anticoagulant to blood can cause shape fluctuations and haemolysis of red blood cells [7]. ...
Article
Mammalian whole blood sources are often used for forensic research and training when human samples cannot be sourced. While porcine, ovine and equine blood have been shown to be viable alternatives to whole human blood for forensic purposes, procurement can still pose a problem, especially for smaller and remote institutions. This work explores the use of whole bovine blood for basic bloodstain simulation. Sample preparation through the addition of ACD-A anticoagulant was optimized and storability was explored. Viscosity, surface tension, density, and packed cell volume, four fluid properties relevant to bloodstain pattern analysis, were monitored over four days and in two temperature conditions. Linear mixed models accounting for variation in the donor demonstrated that these fluid properties of the bovine blood changed predictably over time and with temperature. Whole bovine blood with 12.5% v/v ACD-A was found to be viable for use in basic bloodstain simulation at ambient and physiological temperature.
... Inoculant volume was calculated by dividing the difference in pre-and post-inoculation bottle weights by 1.0581, the density of blood. 22 Data sources and definitions Patient data were abstracted from the electronic medical records. Culture-confirmed infection was defined as growth of a pathogen from at least one blood culture bottle. ...
Article
... Although blood is a non-Newtonian fluid in which viscosity depends on the haematocrit (Berger & Jou, 2000;Pedley & Luo, 1995), it can be assumed as a Newtonian fluid when large arteries, such as the cerebral artery, are simulated (Arzani, 2018;Ku, 1997;Taylor & Figueroa, 2009). Hence, blood in the arterial system was assumed to be an incompressible, Newtonian fluid with a density of 1.06 g cm −3 (Trudnowski & Rico, 1974) and viscosity of 0.04 g s −1 cm −1 (Hall & Hall, 2020). With rigid wall assumptions, a Petrov-Galerkin stabilized finite-element formulation with linear elements (Brooks & Hughes, 1982; was used to calculate the flow velocity and pressure field of the constructed domains. ...
Article
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We investigated the effects of atherosclerosis in the carotid region on cerebral haemodynamics. A total of 15 stenosis cases following NASCET criteria were modelled using patient-specific medical image data and an open-source package, SimVascular. The formulation adopted the stabilised Petrov–Galerkin scheme with Newtonian and incompressible assumptions. The boundary conditions employed pulsatile inflow and three-element lumped Windkessel outlet conditions with a rigid wall assumption. We present transitions in the represented CoW during stenosis progression using three-dimensional aortic-cerebral vasculature for the first time. This was driven by the conserved total cerebral blood flow to 50% carotid stenosis (CS) (P-value, P > 0.05), which deteriorated during subsequent stages of CS (P < 0.01), and the effective collateral capability of the communicating arteries (CoAs) activated from a degree of 75% and above (P < 0.0001). The prevalence of ‘complete’ CoW peaked at 50% CS and then declined. Despite the collateral flow, the ipsilateral hemispheric perfusion was moderately reduced (P < 0.01), and the contralateral perfusion was conserved (P > 0.05), revealing the ineffectiveness of collateral capability of CoW at the extreme stages of CS. We identified bulk cerebral auto-regulation effects of the conventional Windkessel model, demonstrating accurate flow reduction in the stenosed artery.
... The change in water density over the temperature ranges under consideration is trivial and would theoretically not impact measured ethanol concentration. Variations in the density of blood resulting from temperature changes are similar in magnitude to those seen in water [21,22]. ...
Article
Since the accuracy of headspace gas chromatographic analysis of blood for ethanol concentration has been so well established over the past several decades, it has become commonplace in court proceedings to attack preanalytical handling of the blood samples including the lack of measuring sample temperature prior to sample preparation. The impact on measured ethanol concentration of allowing refrigerated (~4℃) samples varying amounts of time to equilibrate with room temperature, 24, 4, 3, 2, and 1 h, prior to sample preparation was evaluated. Samples were diluted 1:10 with an internal standard using a diluter/dispenser and analyzed using headspace gas chromatography. The mean ethanol concentration measured for the sixteen samples at each of the five equilibration times was 0.153 g/dl. The F-critical from the one-way ANOVA was 2.4937. The calculated F value was 0.4209. Additionally, the effect on measured ethanol concentration of having calibrators at different temperatures than case samples was investigated. Three groups were analyzed: all calibrators, controls, and samples given 24 h to equilibrate with room temperature, all calibrators, controls, and samples prepared immediately after removal from refrigeration, and calibrators sampled immediately after removal from refrigerator with samples and controls allowed 24 h to equilibrate with room temperature. The mean ethanol concentration measured for the thirty blood samples in each of the three groups was 0.197 g/dl. The F-critical from the one-way ANOVA was 3.1013. The calculated F value was 0.0188. Measured ethanol concentrations were insensitive to the variations in preanalytical conditions evaluated in this study.
... Optiray® 320 ioversol injection 68% was used as an intravenous contrast agent in our hospital. Its speci c gravity is 1.371; the average speci c gravity of adult blood is approximately 1.0506 at 37 °C [10]. ...
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Background The sign of contrast agent pooling (C.A.P.) in dependent part of the venous system were reported in some case reports, which happened in the patients before sudden cardiac arrest. Until now, there is no solid evidence enough to address the importance of the sign. This study aimed to assess the accuracy of the C.A.P. sign in predicting imminent cardiac arrest and the association of the C.A.P. sign with patient’s survival.Methods This is a retrospective cohort study. The study included 128 patients who visited the emergency department of Far Eastern Memorial Hospital, who received contrast computed tomography (CT) scan and then experienced cardiac arrest at the emergency department (from January 1, 2016 to December 31, 2018). With positive C.A.P. sign, the primary outcome is whether in-hospital cardiac arrest happens within an hour; the secondary outcome is survival to discharge.ResultsIn the study, 8.6% (N=11) patients had positive C.A.P. sign and 91.4% (N=117) patients did not. The accuracy of C.A.P. sign in predicting cardiac arrest within 1 hour is 85.94%. The C.A.P. sign had a positive association with IHCA within 1 hour after the CT scan (adjusted odds ratio 11.60, 95% conﬁdence interval [CI] 1.97 – 68.20). The odd ration of survival to discharge is 0.0081 with positive C.A.P. sign (95% CI 0.00697 – 2.188).Conclusion The C.A.P. sign can be considered as an alarm for imminent cardiac arrest and poor prognosis. The patients with positive C.A.P. sign were more likely to experience imminent cardiac arrest; in contrast, less likely to survive. Trial registrationThe study was approved by our institutional ethical committee (IRB No.108107-E).
... The blood flow is modeled as an incompressible, Newtonian fluid governed by the Navier-Stokes equations where 0 ∈ ℝ >0 is the density of the fluid, ∈ ℝ >0 is the kinematic viscosity of the fluid, and v ∶ Ω → ℝ d and P ∶ Ω → ℝ >0 are the velocity and pressure, respectively, of the fluid implicitly defined as the solution of (2). In this work, we assume the fluid is blood and take the material properties to be 0 = 1060 kg/m 3 [36] and = 2.83 × 10 −6 m 2 /s [37] for both test cases. We consider the case where the flow has reached a steady state and the time derivative, v t , vanishes. ...
Preprint
Simulation-based imaging (SBI) is a blood flow imaging technique that optimally fits a computational fluid dynamics (CFD) simulation to low-resolution, noisy magnetic resonance (MR) flow data to produce a high-resolution velocity field. In this work, we study the effectivity of SBI in predicting wall shear stress (WSS) relative to standard magnetic resonance imaging (MRI) postprocessing techniques using two synthetic numerical experiments: flow through an idealized, two-dimensional stenotic vessel and a model of an adult aorta. In particular, we study the sensitivity of these two approaches with respect to the Reynolds number of the underlying flow, the resolution of the MRI data, and the noise in the MRI data. We found that the SBI WSS reconstruction: 1) is insensitive to Reynolds number over the range considered (Re $\leq$ 1000), 2) improves as the amount of MRI data increases and provides accurate reconstructions with as little as three MRI voxels per diameter, and 3) degrades linearly as the noise in the data increases with a slope determined by the resolution of the MRI data. We also consider the sensitivity of SBI to the resolution of the CFD mesh and found there is flexibility in the mesh used for SBI, although the WSS reconstruction becomes more sensitive to other parameters, particularly the resolution of the MRI data, for coarser meshes. This indicates a fundamental trade-off between scan time (i.e., MRI data quality and resolution) and reconstruction time using SBI, which is inherently different than the trade-off between scan time and reconstruction quality observed in standard MRI postprocessing techniques.
... The pipette tips (Bioclean) were washed with ultrapure water (PURELAB Option-Q, ELGA, UK) before use. The precise mass of each blood sample was measured (Sartorius balance with Sartorius SartoCollect Software, Krugersdorp, South Africa) and converted back to volume by using the average density of whole blood (1.06 g/mL) (Trudnowski and Rico, 1974). Then 1.0 mL ultrapure concentrated nitric acid was added using a 5 mL bottle-top dispenser (Seastar Chemicals, Sidney, BC, Canada). ...
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Background: Biomonitoring of a cohort within a large health survey can provide reliable information on trace element status. The main aims of this study were 1) to determine the concentrations of 28 trace elements in whole blood samples from the general population of the Nord-Trøndelag region, Norway, and 2) to investigate how trace element concentrations vary with geographical area, lifestyle, and socio-demographic factors. Methods: Whole blood samples were collected in the third survey of the Trøndelag Health Survey (HUNT3), a large population-based study in Norway. In total, 1011 whole blood samples from individuals aged 20-91 years were analyzed using high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). We compared trace element concentrations (As, B, Be, Br, Ca, Cd, Cr, Cs, Cu, Ga, Au, In, Fe, Pb, Hg, Tl, Mg, Mn, Mo, Ni, Rb, Sc, Se, Ag, Sr, Sn, W and Zn) between three geographical areas (coastal, fjord/town, inland/mountain) using multivariable linear regression and assessed differences in trace element concentrations with socio-demographic and lifestyle factors using general linear models. Results: Trace element concentrations were generally comparable to levels reported in other recent studies and suggest low exposure to toxic trace elements in the region. We found geographical differences in concentrations of 19 trace elements. As, Br, Hg, and Se concentrations were higher on the coast compared to the fjord/town and inland/mountain areas, suggesting that the marine environment is an important source of exposure for these trace elements. In addition, socio-demographic and lifestyle characteristics, particularly age and sex, were associated with differences in trace element concentrations. Conclusions: We report concentrations of 28 trace elements in the general population of a rural region with low exposure to pollution. Whole blood concentrations of trace elements varied with geographical area, the participants' lifestyle, and socio-demographic characteristics, highlighting the importance of considering these factors when evaluating trace element status in a population.
... It is widely accepted that the density and viscosity of blood can be assumed to be constant across space and time. The density of blood is shown to be homogeneous across individuals, 1050 kg/m 3 (95% CI 1048-1054 kg/m 3 ) [19]. The viscosity of blood is known to be shear-thinning which may affect the blood flow pattern and eventually FFR. ...
Article
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Computations of fractional flow reserve, based on CT coronary angiography and computational fluid dynamics (CT-based FFR) to assess the severity of coronary artery stenosis, was introduced around a decade ago and is now one of the most successful applications of computational fluid dynamic modelling in clinical practice. Although the mathematical modelling framework behind this approach and the clinical operational model vary, its clinical efficacy has been demonstrated well in general. In this review, technical elements behind CT-based FFR computation are summarised with some key assumptions and challenges. Examples of these challenges include the complexity of the model (such as blood viscosity and vessel wall compliance modelling), whose impact has been debated in the research. Efforts made to address the practical challenge of processing time are also reviewed. Then, further application areas – myocardial bridge, renal stenosis and lower limb stenosis – are discussed along with specific challenges expected in these areas.
... This is acceptable for large-artery simulations such as those involving the cerebral artery (Ku, 1997;Taylor & Figueroa, 2009;Arzani, 2018). Further, blood was assumed to be incompressible, which rendered the blood density and viscosity constants at 1.06 g·cm −3 (Trudnowski & Rico, 1974) and 0.04 g·s −1 ·cm −1 (Hall & Hall, 2020), respectively. The assumption of a rigid-body vessel wall was effective for simulating relatively realistic artery behavior at a reasonable computational cost. ...
Article
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Haemodynamic correlations among the pulsatility index (PI), resistive index (RI), time to peak velocity (TPV), and mean Reynolds number (ReMean) were numerically investigated during the progression of carotid stenosis (CS), a highly prevalent condition. Fifteen patient-specific CS cases were modeled in the package, SimVascular, by using computed tomography angiography data for the aortic-cerebral vasculature. Computational fluid domains were solved with a stabilized Petrov–Galerkin scheme under Newtonian and incompressible assumptions. A rigid vessel wall was assumed, and the boundary conditions were pulsatile inflow and three-element lumped Windkessel outlets. During the progression, the increase in the TPV resembled that during aortic stenosis, and the parameter was negatively correlated with PI, RI, and ReMean in the ipsilateral cerebral region. The ReMean was inversely related to PI and RI on the contralateral side. In particular, PI and RI in cerebral arteries showed three second-order regression patterns: ‘constant (Group A)’, ‘moderately decreasing (Group B)’, and ‘decreasing (Group C)’. The patterns were defined using a new parameter, mean ratio (lowest mean index/mean index at 0% CS). This parameter could effectively indicate stenosis-driven tendencies in local haemodynamics. Overall, the haemodynamic indices changed drastically during severe unilateral CS, and they reflected both regional and aortic-cerebral flow characteristics.
... A typical size of a = Rr RBC is considered, where r RBC = 4 µm is the average radius of an erythrocyte and R is a parameter reflecting the ratio between the size of erythrocytes and a characteristic size of fluid channels within the gel [12,18,19]. The density difference is approximately ∆ρ ≈ 80 kg/m 3 [34,35]. Starting from the initial conditions for the height h 0 and volume fraction φ 0 , and taking into account the usual delay time t 0 for the gel collapse [12,14,26], the height of the gel as a function of time becomes ...
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The erythrocyte (or red blood cell) sedimentation rate (ESR) is commonly interpreted as a measure of cell aggregation and as a biomarker of inflammation. It is well known that an increase of fibrinogen concentration, an aggregation-inducing protein for erythrocytes, leads to an increase of the sedimentation rate of erythrocytes, which is generally explained through the formation and faster settling of large disjoint aggregates. However, many aspects of erythrocyte sedimentation conform well with the collapse of a colloidal gel rather than with the sedimentation of disjoint aggregates. Using experiments and cell-level numerical simulations, we systematically investigate the dependence of ESR on fibrinogen concentration and its relation to the microstructure of the gel-like erythrocyte suspension. We show that for physiological aggregation interactions, an increase in the attraction strength between cells results in a cell network with larger void spaces. This geometrical change in the network structure occurs due to anisotropic shape and deformability of erythrocytes and leads to an increased gel permeability and faster sedimentation. Our results provide a comprehensive relation between the ESR and the cell-level structure of erythrocyte suspensions and support the gel hypothesis in the interpretation of blood sedimentation.
... A typical size of a = Rr RBC is considered, where r RBC = 4 µm is the average radius of an erythrocyte and R is a parameter reflecting the ratio between the size of erythrocytes and a characteristic size of fluid channels within the gel [12,18,19]. The density difference is approximately ∆ρ ≈ 80 kg/m 3 [34,35]. Starting from the initial conditions for the height h 0 and volume fraction ϕ 0 , and taking into account the usual delay time t 0 for the gel collapse [12,14,26], the height of the gel as a function of time becomes ...
Article
Full-text available
The erythrocyte (or red blood cell) sedimentation rate (ESR) is commonly interpreted as a measure of cell aggregation and as a biomarker of inflammation. It is well known that an increase of fibrinogen concentration, an aggregation-inducing protein for erythrocytes, leads to an increase of the sedimentation rate of erythrocytes, which is generally explained through the formation and faster settling of large disjoint aggregates. However, many aspects of erythrocyte sedimentation conform well with the collapse of a particle gel rather than with the sedimentation of disjoint aggregates. Using experiments and cell-level numerical simulations, we systematically investigate the dependence of ESR on fibrinogen concentration and its relation to the microstructure of the gel-like erythrocyte suspension. We show that for physiological aggregation interactions, an increase in the attraction strength between cells results in a cell network with larger void spaces. This geometrical change in the network structure occurs due to anisotropic shape and deformability of erythrocytes and leads to an increased gel permeability and faster sedimentation. Our results provide a comprehensive relation between the ESR and the cell-level structure of erythrocyte suspensions and support the gel hypothesis in the interpretation of blood sedimentation.
... Optiray ® 320 ioversol injection 68% was used as an intravenous contrast agent in our hospital. Its specific gravity is 1.371; the average specific gravity of adult blood is approximately 1.0506 at 37 °C [10]. The results of CT scans were evaluated by two senior emergency physicians (with Cohen's kappa coefficient 0.82) who were masked to C.A.P sign status and patients' outcomes. ...
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Background The sign of contrast agent pooling (C.A.P.) in dependent part of the venous system were reported in some case reports, which happened in the patients before sudden cardiac arrest. Until now, there is no solid evidence enough to address the importance of the sign. This study aimed to assess the accuracy of the C.A.P. sign in predicting imminent cardiac arrest and the association of the C.A.P. sign with patient’s survival. Methods This is a retrospective cohort study. The study included all patients who visited the emergency department, who received contrast computed tomography (CT) scan and then experienced cardiac arrest at the emergency department (from January 1, 2016 to December 31, 2018). We evaluated the occurrence of the C.A.P. sign on the chest or abdominal CT scan, patients with ECMO were excluded. With positive C.A.P. sign, the primary outcome is whether in-hospital cardiac arrest happens within an hour; the accuracy of C.A.P. sign was calculated. The secondary outcome is survival to discharge. Results In the study, 128 patients were included. 8.6% (N = 11) patients had positive C.A.P. sign and 91.4% (N = 117) patients did not. The accuracy of C.A.P. sign in predicting cardiac arrest within 1 h was 85.94%. The C.A.P. sign had a positive association with IHCA within 1 h after the CT scan (adjusted odds ratio 7.35, 95% confidence interval [CI] 1.27 – 42.69). The relative risk (RR) of survival to discharge was 0.90 with positive C.A.P. sign (95% CI 0.85 – 0.96). Conclusions The C.A.P. sign can be considered as an alarm for imminent cardiac arrest and poor prognosis. The patients with positive C.A.P. sign were more likely to experience imminent cardiac arrest; in contrast, less likely to survive. Trial registration IRB No.108107-E.
... [2], which includes Refs. [54][55][56], for further justification). ...
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The erythrocyte sedimentation rate is one of the oldest medical diagnostic methods whose physical mechanisms remain debatable today. Using both light microscopy and mesoscale cell-level simulations, we show that erythrocytes form a soft-particle gel. Furthermore, the high volume fraction of erythrocytes, their deformability, and weak attraction lead to unusual properties of this gel. A theoretical model for the gravitational collapse is developed, whose predictions are in agreement with detailed macroscopic measurements of the interface velocity.
... The density of blood is 1.06 g/mL. [15] The weight of the blood was divided by 1.06 g/mL and the quotient used to estimate the volume of blood in the vacutainer tube. ...
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Although both the erythrocyte sedimentation rate (ESR) and optically measured erythrocyte aggregation parameters are affected by the hematocrit, this interaction is not considered by the method used to estimate ESR that considers aggregation parameters. In this study, we investigated the relationship between the ESR obtained by the Westergren method and that obtained with an aggregation parameter, namely, the aggregation index (AI) of multiple hematocrit values and fibrinogen-spiked samples with an analysis time of 5–60 s, and attempted to develop a rapid and accurate ESR estimation method. The AIs obtained from 5- and 10-s optical measurements with a fixed hematocrit were highly correlated with the erythrocyte sedimentation velocity. Furthermore, the rate of the AI increase with an increasing hematocrit was not significantly affected by the fibrinogen concentration at these measurement times. On the basis of these results, we defined the hematocrit-corrected aggregation index (HAI). The exponential function of the HAI obtained from the 5-s measurement agreed well with the sedimentation velocity calculated to eliminate the effect of hindered settling, and the HAI and hematocrit could be used to calculate the time constant of the sedimentation curve with a linear regression equation. The ESR value at 1 h was calculated based on the modified Stokes’ law and the HAI obtained from the 5-s measurement and showed an excellent correlation ( R = 0.966) with the ESR value obtained by the Westergren method over a wide range of hematocrit and fibrinogen concentrations.
... Beforehand, the empty blood culture bottles of the aerobic-resin and anaerobic-lytic blood culture (BD) media were weighed. Combined with the specific weight of the blood (set as 1.057 g per mL) [16], the target weight range of optimal blood-filling was defined as corresponding to 8-10 mL of blood per bottle, according to the manufacturer (aerobic: 68.36-71.2 g; anaerobic: 69.26-72.37 ...
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Bloodstream infections increase morbidity and mortality in hospitalized patients and pose a significant burden for health care systems worldwide. Optimal blood culture diagnostics are essential for early detection and specific treatment. After assessing the quality parameters at a surgical intensive care unit for six months, we implemented a diagnostic stewardship bundle (DSB) to optimize blood culture diagnostics and then reevaluated its effects after six months. Material and Methods: All patients ≥ 18 years old and on the ward were included: pre-DSB 137 and post-DSB 158. The standard quality parameters were defined as the number of blood culture sets per diagnostic episode (≥2), the rate of contamination (2–3%), the rate of positivity (5–15%), the collection site (≥1 venipuncture per episode) and the filling volume of the bottles (8–10 mL, only post-DSB). The DSB included an informational video, a standard operating procedure, and ready-to-use paper crates with three culture sets. Results: From pre- to post-interventional, the number of ≥2 culture sets per episode increased from 63.9% (257/402) to 81.3% (230/283), and venipunctures increased from 42.5% (171/402) to 77.4% (219/283). The positivity rate decreased from 15.1% (108/714) to 12.8% (83/650), as did the contamination rate (3.8% to 3.6%). The majority of the aerobic bottles were filled within the target range (255/471, 54.1%), but in 96.6%, the anaerobic bottles were overfilled (451/467). Conclusions: The implementation of DSB improved the quality parameters at the unit, thus optimizing the blood culture diagnostics. Further measures seem necessary to decrease the contamination rate and optimize bottle filling significantly.
... The blood flow is modeled as an incompressible, Newtonian fluid governed by the Navier-Stokes equations where 0 ∈ ℝ >0 is the density of the fluid, ∈ ℝ >0 is the kinematic viscosity of the fluid, and v ∶ Ω → ℝ d and P ∶ Ω → ℝ >0 are the velocity and pressure, respectively, of the fluid implicitly defined as the solution of (2). In this work, we assume the fluid is blood and take the material properties to be 0 = 1060 kg/m 3 [36] and = 2.83 × 10 −6 m 2 /s [37] for both test cases. We consider the case where the flow has reached a steady state and the time derivative, v t , vanishes. ...
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Simulation-based imaging (SBI) is a blood flow imaging technique that optimally fits a computational fluid dynamics (CFD) simulation to low-resolution, noisy magnetic resonance (MR) flow data to produce a high-resolution velocity field. In this work, we study the effectivity of SBI in predicting wall shear stress (WSS) relative to standard magnetic resonance imaging (MRI) postprocessing techniques using two synthetic numerical experiments: steady flow through an idealized, two-dimensional stenotic vessel and a model of an adult aorta. In particular, we study the sensitivity of these two approaches with respect to the Reynolds number of the underlying flow, the resolution of the MRI data, and the noise in the MRI data. We found that the SBI WSS reconstruction: (1) is insensitive to Reynolds number over the range considered ( $$\mathrm {Re} \le 1000$$ Re ≤ 1000 ), (2) improves as the amount of MRI data increases and provides accurate reconstructions with as little as three MRI voxels per diameter, and (3) degrades linearly as the noise in the data increases with a slope determined by the resolution of the MRI data. We also consider the sensitivity of SBI to the resolution of the CFD mesh and found there is flexibility in the mesh used for SBI, although the WSS reconstruction becomes more sensitive to other parameters, particularly the resolution of the MRI data, for coarser meshes. This indicates a fundamental trade-off between scan time (i.e., MRI data quality and resolution) and reconstruction time using SBI, which is inherently different than the trade-off between scan time and reconstruction quality observed in standard MRI postprocessing techniques.
... The density of blood is 1.06 g/mL. [15] The weight of the blood was divided by 1.06 g/mL and the quotient used to estimate the volume of blood in the vacutainer tube. ...
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Background. Prevention of iatrogenic blood loss is an essential component of patient blood management (PBM) in intensive care units (ICUs). The amount of iatrogenic blood loss from diagnostic phlebotomy in the ICUs at Universitas Academic Hospital, Free State Province, South Africa, is unknown.Objective. To quantify diagnostic phlebotomy volumes, and volumes submitted in excess for diagnostic testing in the ICU. Methods. We conducted a prospective descriptive observational study on adults who were admitted to ICUs at a single centre over a period of 14 days. The weight of each filled phlebotomy tube was calculated using the specific gravity of blood and averages of empty phlebotomy tubes, establishing the total volume.Results. Data from 59 participants with a median length of stay at the ICU of 3 days were analysed. The median phlebotomy volume was 7.0 mL day and 13.6 mL/ICU admission. The volume of blood required for analysis daily and ICU admission was 0.7 mL and 2.2 mL, respectively. The median phlebotomy volume in excess of the amount required for analysis daily and ICU admission was 5.05 mL and 12.11 mL, respectively. Conclusion. While the median excess daily phlebotomy volume in this present study may seem insignificant and underestimating the true excess of phlebotomy volume, interventions to reduce phlebotomy volumes and development of a PBM guideline for appropriate phlebotomy volumes and preventing wastage of patients’ blood in the ICU is required.
... Hydrostatic pressure difference mmHg ð Þ ¼distance cm ð Þ Â 1:06=13:6 Â 10 This is based on the assumption that the specific gravity of mercury at 37 C (density: 13,500 kg/m 3 ) as compared with water at 37 C (density 993 kg/m 3 ) is 13.6, and the specific gravity of whole blood at 37 C as compared with water at 37 C is 1.06 (25). ...
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Background: Steady-state cerebral blood flow (CBF) and dynamic cerebral autoregulation are reportedly maintained during -10° head-down tilt (HDT) despite slight increases in intracranial pressure (ICP). However, the higher ICP during -30° HDT may alter steady-state CBF and dynamic cerebral autoregulation. The present study hypothesized that steady-state CBF and dynamic cerebral autoregulation would be altered by higher ICP during -30° HDT than during 0° and -10° HDT. Methods: Seventeen healthy participants were positioned horizontal (0°) and in -10° HDT and -30° HDT for 10 min in random order on separate days. The arterial blood pressure waveform was obtained using a finger blood pressure device and the cerebral blood velocity waveform in the middle cerebral artery was obtained using transcranial Doppler sonography (TCD) for the last 6 min in each position. ICP was estimated using non-invasive ICP (nICP) based on TCD. Dynamic cerebral autoregulation was evaluated by spectral and transfer function analysis. Results: Although nICP was significantly higher during -30° HDT (12.4 mmHg) than during -10° HDT (8.9 mmHg), no significant differences in steady-state mean cerebral blood velocity or transfer function gain in any frequency ranges were seen among all angles of HDT. Conclusion: Counter to our hypothesis, the present results suggest that steady-state CBF and dynamic cerebral autoregulation may be preserved during short-term -30° HDT despite the higher ICP compared to that during -10° HDT.
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The Widmark equation is used forensically for the determination of the amount of ethanol (alcohol) that may have been consumed and also to determine the blood alcohol concentration (BAC) of an individual at a specific time. It is important to be able to estimate the uncertainty associated with Widmark equations. To date, there has been no detailed determination of contribution to the final uncertainty of Widmark calculations of the volume of distribution of ethanol (Vd), using anthropometric equations, or the contribution of an individual’s body mass. Using published data, published literature, and freedom of information data, we determined that the variability (%CV) associated with Vd was ~10% (Watson et al. and Forrest anthropometric equations) and that the %CV associated with estimated body mass was ~15% compared to ~3% when body mass was directly measured. These data allow an estimation of the overall uncertainty of Widmark calculations using general error propagation. The estimated total uncertainty for BAC calculations increased from ~11% (volume consumed) and ~22% (BAC) to ~19% (volume consumed) and ~37% (BAC) when using measured body mass compared to estimated body mass. These results demonstrate that forensic practitioners should be mindful of the increase in estimated uncertainty in calculated Widmark equation results when estimated body mass is used rather than measured body mass. These data further improve the knowledge around the uncertainty of results calculated with the Widmark equation.
Thesis
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In human medicine, vascular diseases are important and independently linked with mortality. Changes in arterial structure and function contribute to a poorer ‘vascular health’. The latter is mainly assessed by determination of arterial wall stiffness, regionally and locally. Using different techniques it has been demonstrated that age, race and gender have an effect on the arterial wall stiffness. In horses, the most important, often fatal, vascular disorder is arterial rupture. This condition has been associated with breed (e.g. aortic rupture in Friesians), age, exercise, parturition, copulation and α1-agonist treatment. Nevertheless, knowledge of the pathophysiology of arterial rupture and the effect of age and breed remained very limited, since up till now, techniques to measure and assess arterial wall stiffness were not available. The General introduction of this thesis gives an overview of normal and abnormal structural, biomechanical and functional properties of the arterial wall in humans and the current knowledge in equines. First the normal structure of the arterial wall is described, followed by an explanation of the physiological function of the arterial tree. This includes an overview of blood pressure regulation and different blood pressure measurement techniques, followed by a description of normal blood pressure in horses. Next, an outline of the biomechanical properties of the arterial wall is given, combined with possible ex vivo tests to describe these biomechanical properties. This is followed by a short description of the most used mathematical models that allow studying arterial tree flow dynamics and pressure waves. Measuring techniques for arterial wall stiffness assessment in human patients are described, together with the effect of aging, gender, training and race. Lastly, the most common arterial disorders in horses are described, including exercise-induced arterial rupture, aortocardiac fistulation, aortopulmonary fistulation in Friesians horses and arterial rupture associated with phenylephrine administration or parturition. The first objective of this dissertation was to predict and understand flow profiles and pressures over the whole arterial tree of the healthy horse (Chapter 3). First, we have detailed the anatomy of the equine arterial tree (diameter, branch length and branching angle of 113 arterial segments). Based on these details, together with literature data, physiological data from ultrasound images and invasive blood pressure measurements, we have developed a mathematical one-dimensional model which mimics the arterial flow in horses. Adapting the model by taking into account gravity improved predicted flow waveform morphology. Outcomes of this model showed plausible predictions of pressures and flow waves throughout the arterial tree. Moreover, simulated flow waveforms showed a similar oscillating pattern as observed in ultrasound Doppler images. Wave power analysis helped to explain the contours of arterial flow profiles. Techniques to reliably measure arterial wall stiffness in horses were developed and applied (Chapter 4). Regional arterial wall stiffness parameters, aortic to external iliac artery pulse wave velocity and carotid to external iliac artery pulse wave velocity calculated using pulsed wave Doppler, showed low coefficients of variation (3-15%). Local arterial wall stiffness parameters including diameter and lumen area change, diameter and lumen area strain, compliance, distensibility and stiffness index of the cranial and caudal common carotid artery, proximal aorta and external iliac artery showed low to high coefficients of variation (10-68%). We concluded that local arterial wall stiffness parameters are, in contrary to regional arterial wall stiffness parameters, not suitable for individual follow-up of patients, but can have an added value for population research. In Chapter 5, the previously developed techniques were used to assess differences in arterial wall stiffness between Warmblood horses and Friesian horses, as Friesians are known to be predisposed to aortic rupture. Aortic to external iliac artery and carotid to external iliac artery pulse wave velocity were significantly higher in Friesians horses compared to Warmblood horses (6.52±2.51 and 7.06±1.60 m/s vs. 5.95±0.94 and 5.79±1.43 m/s), indicating a stiffer aorta in Friesians. This could be confirmed by lower local arterial wall stiffness parameters in Friesians. Additionally Friesian horses showed a significantly higher systolic (146±18 mmHg), diastolic (97±12 mmHg) and mean arterial blood pressure (115±15 mmHg) and a higher pulse pressure (49±9 mmHg) compared to Warmblood horses (135±14 mmHg, 91±10 mmHg, 106±13 mmHg and 44±9 mmHg, respectively). These findings, in combination with the previously described differences in collagen amount and cross-linking pattern, make it highly probable that the predisposition of Friesian horses to aortic rupture is, at least partially, related to increased arterial wall stiffness. In Chapter 6, the effect of age on the arterial wall stiffness in horses was assessed using the same techniques. Older horses showed significantly larger arterial diameters compared to young horses, in combination with an increased arterial wall thickness. Aortic to external and carotid to external iliac artery pulse wave velocity were clearly higher in old horses (6.2±1.3 m/s and 6.0±2.2 m/s) compared to young horses (5.3±0.6 m/s and 4.6±0.8 m/s), in combination with lower local aortic and carotid arterial wall stiffness parameters, confirming stiffer arteries in older horses. No difference in blood pressure was found. Arterial compliance was maximal in the aorta and decreased towards the periphery. Results indicate that horses, in accordance with humans, present age-related arterial wall stiffening, in combination with luminal enlargement and arterial wall thickening. In Chapter 7 we aimed at investigating the structural and biomechanical effects of aging on the equine arterial wall. Histological findings showed a decrease in the amount of elastin from the proximal aorta (34±3%) towards the peripheral arteries (8±5% in the median artery). A significant increase in wall thickness in aged horses was found, in combination with an increased area % of smooth muscle actin. Biomechanical properties were assessed using an inflation-extension test pressurising (15-300 mmHg) proximal aortas, distal aortas, common carotid arteries and external iliac arteries. Rupture occurred in a minority of arteries (8/78) at high pressures (250-300mmHg), and mostly occurred in older horses (7/8). Age significantly affected the pressure-area curve of the distal aorta, common carotid artery and external iliac artery, the pressure-compliance curve of the proximal aorta and the common carotid artery, and the pressure-distensibility curve of the proximal aorta. Larger vascular cross-sectional areas at the same pressure were found in older horses, combined with a lower compliance in older horses at physiological pressures. Results indicate structural and biomechanical arterial wall changes due to aging, which explain the in vivo differences in arterial wall stiffness between young and old horses. As a general conclusion, by providing new insights in equine arterial physiology, this work contributes to the knowledge of the pathophysiology of arterial rupture in horses. A unique dataset of the equine arterial tree is provided, in combination with an equine specific mathematic model to study and predict the normal blood flow and pressure waves in horses. This model can be a starting point for studying arterial pathophysiology during hypertension, exercise or drug administration in future. A technique to study vascular health in the standing, unsedated horse by measuring local and regional arterial wall stiffness is described. We have demonstrated that age affects the arterial wall stiffness in vivo which corresponds to structural and biomechanical changes observed ex vivo. Furthermore, we have demonstrated that Friesians have a stiffer aorta, which could predispose this breed to aortic rupture. In future it would be useful to assess the effect of breed (other than Friesians), gender and training on the arterial wall stiffness, in order to further unravel the underlying causes of arterial rupture in horses.
Chapter
In this paper, a study has been carried out to understand the effect of the fluid, flow and the mechanical parameters on a pulsatile flow of a Newtonian fluid in an expanding and contracting pipe. The fluid parameters considered are the viscosity and the density, flow parameters are the amplitude of the pressure gradient and the frequency of oscillations, and the mechanical parameter considered is the radius of the pipe. A mathematical model is constructed in the cylindrical polar coordinate system with the fluid flow assumed to be axisymmetric. Further, the fluid is taken to be incompressible, and the radius of the pipe to vary with time. Navier–Stokes equations are used to describe this fluid flow problem. The resulting nonlinear coupled system of equations together with an appropriate boundary and initial conditions is solved using the homotopy perturbation method. The model is then applied to the human circulatory system, and the effect of the three sets of parameters on wall shear stress and volumetric flux is studied. Data for the model parameters are taken from literature on human blood, and human circulatory system and graphs have been plotted to understand their effect on the flow.
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This study aimed to evaluate a newly designed circulatory mock loop intended to model cardiac and circulatory hemodynamics for mechanical circulatory support device testing. The mock loop was built with dedicated ports suitable for attaching assist devices in various configurations. This biventricular mock loop uses two pneumatic pumps (Abiomed AB5000 ™ , Danvers, MA, USA) driven by a dual-output driver (Thoratec Model 2600, Pleasanton, CA, USA). The drive pressures can be individually modified to simulate a healthy heart and left and/or right heart failure conditions, and variable compliance and fluid volume allow for additional customization. The loop output for a healthy heart was tested at 4.2 L/min with left and right atrial pressures of 1 and 5 mm Hg, respectively; a mean aortic pressure of 93 mm Hg; and pulmonary artery pressure of 17 mm Hg. Under conditions of left heart failure, these values were reduced to 2.1 L/min output, left atrial pressure = 28 mm Hg, right atrial pressure = 3 mm Hg, aortic pressure = 58 mm Hg, and pulmonary artery pressure = 35 mm Hg. Right heart failure resulted in the reverse balance: left atrial pressure = 0 mm Hg, right atrial pressure = 30 mm Hg, aortic pressure = 100 mm Hg, and pulmonary artery pressure = 13 mm Hg with a flow of 3.9 L/min. For biventricular heart failure, flow was decreased to 1.6 L/min, left atrial pressure = 13 mm Hg, right atrial pressure = 13 mm Hg, aortic pressure = 52 mm Hg, and pulmonary artery pressure = 18 mm Hg. This mock loop could become a reliable bench tool to simulate a range of heart failure conditions.
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Background There is growing evidence of an association between cadmium (Cd) and unfavorable birth outcomes. The effect of Cd exposure on anthropometric measures at birth or small for gestational age (SGA) infants in a large, nationwide Japanese cohort remains to be clarified. Objectives To analyze the association between maternal blood Cd levels at different sampling times and sex-dependent infant birth size, weight, body length, chest, and head circumferences, in addition to SGA. Methods Data of 17,584 pregnant women in the Japan Environment and Children’s Study were analyzed for anthropometric measurements. For SGA determination, 13,969 cases of vaginal delivery were analyzed after excluding infants born by cesarean section. Maternal blood Cd levels were categorized into quartiles (Q1–Q4), and the Q1 was used as a reference. Multiple linear regression analysis was performed for anthropometric measurements, and multiple logistic regression analysis was used to investigate the association of maternal blood Cd levels with the risk of SGA. Results Birth weight tended to decrease according to the increase in quartiles of blood Cd levels (15.63 g decrease [95% confidence level (CI): -33.26, 2.01] for Q4). The overall analysis revealed no decreases in body length and head and chest circumference, but subgroup analysis revealed that chest circumference tended to decrease according to the increase in quartiles in the female sex/third-trimester stratification (0.16 cm decrease [95% CI: -0.32, 0.00] for Q4). SGA risk was also higher and paralleled the increase in blood Cd levels associated with the female sex/third-trimester group (Odds Ratio 1.90 [95% CI: 1.23, 2.94] for Q4). Conclusion Our results provide further evidence of sex-specific health risks associated with Cd exposure in early life in a large Japanese pregnancy cohort.
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Direct contact with toxicants in crude oil during embryogenesis causes cardiovascular defects, but the effects of exposure to airborne volatile organic compounds released from spilled oil are not well understood. The effects of crude oil-derived airborne toxicants on peripheral blood flow were examined in Gulf killifish (Fundulus grandis) since this model completes embryogenesis in the air. Particle image velocimetry was used to measure in vivo blood flow in intersegmental arteries of control and oil-exposed embryos. Significant effects in oil-exposed embryos included increased pulse rate, reduced mean blood flow speed and volumetric flow rate, and decreased pulsatility, demonstrating that normal-appearing oil-exposed embryos retain underlying cardiovascular defects. Further, hematocrit moderately increased in oil-exposed embryos. This study highlights the potential for fine-scale physiological measurement techniques to better understand the sub-lethal effects of oil exposure and demonstrates the efficacy of Gulf killifish as a unique teleost model for aerial toxicant exposure studies. Link to full text: https://authors.elsevier.com/c/1biwFB8ccoKj9
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A promising application of paper microfluidics is the translation of gold-standard multi-step laboratory tests to a disposable paper-based format for decentralized diagnostic or therapeutic testing. This often entails conversion of bench-top processing of macro-volume samples to the processing of micro-volume samples within a porous matrix, and requires detailed characterization of fluid and reagent interactions within the porous material(s) of the device. The current study focuses on rational device design through the characterization of fluid and reagent interactions in polysulfone and glass fiber substrates for multi-step sample processing. Specifically, we demonstrate how the characterization of fluidic compatibility between substrates, chemical compatibility between reagents and substrates, sample pH, and sample transport can be used to inform device design in the context of a two-reaction detection scheme for phenylalanine in porous materials. Finally, we demonstrate detection of phenylalanine from human whole blood, and discuss the multiple strengths of the current design over a previous version.
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We investigate the capacity of published numerical models of thrombin generation to reproduce experimentally observed threshold behaviour under conditions in which diffusion and/or flow are important. Computational fluid dynamics simulations incorporating species diffusion, fluid flow, and biochemical reactions are compared with published data for thrombin generation in vitro in (i) quiescent plasma exposed to patches of tissue factor and (ii) plasma perfused through a capillary coated with tissue factor. Clot time is correctly predicted in individual cases, and some models qualitatively replicate thrombin generation thresholds across a series of tissue factor patch sizes or wall shear rates. Numerical results suggest that there is not a genuine patch size threshold in quiescent plasma—clotting always occurs given enough time—whereas the shear rate threshold observed under flow is a genuine physical limit imposed by flow-mediated washout of active coagulation factors. Despite the encouraging qualitative results obtained with some models, no single model robustly reproduces all experiments, demonstrating that greater understanding of the underlying reaction network, and particularly of surface reactions, is required. In this direction, additional simulations provide evidence that (i) a surface-localised enzyme, speculatively identified as meizothrombin, is significantly active towards the fluorescent thrombin substrate used in the experiments or, less likely, (ii) thrombin is irreversibly inhibited at a faster-than-expected rate, possibly explained by a stimulatory effect of plasma heparin on antithrombin. These results highlight the power of simulation to provide novel mechanistic insights that augment experimental studies and build our understanding of complex biophysicochemical processes. Further validation work is critical to unleashing the full potential of coagulation models as tools for drug development and personalised medicine.
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There is a long history of research examining red blood cell (RBC) partitioning in microvasculature bifurcations. These studies commonly report results describing partitioning that exists as either regular partitioning, which occurs when the RBC flux ratio is greater than the bulk fluid flow rate ratio, or reverse partitioning when the RBC flux ratio is less than or equal to that of the bulk fluid flowrate. This paper presents a study of RBC partitioning in a single bifurcating microchannel with dimensions of 6 to 16 μm, investigating the effects of hematocrit, channel width, daughter channel flowrate ratio, and bifurcation angle. The erythrocyte flux ratio, N*, manifests itself as either regular or reverse partitioning, and time‐dependent partitioning is much more dynamic, occurring as both regular and reverse partitioning. We report a significant reduction in the well‐known sigmoidal variation of the erythrocyte flux ratio (N*) versus the volumetric flowrate ratio (Q*), partitioning behavior with increasing hematocrit in microchannels when the channel dimensions are comparable to cell size. RBCs “lingering” or jamming at the bifurcation were also observed and quantified in vitro. Results from trajectory analyses suggest that the RBC position in the feeder channel strongly affects both partitioning and lingering frequency of RBCs, with both being significantly reduced when RBCs flow on streamlines near the edge of the channel as opposed to the center of the channel. Furthermore, our experiments suggest that even at low Reynolds number, partitioning is affected by the bifurcation angle by increasing cell‐cell interactions. The presented results provide further insight into RBC partitioning as well as perfusion throughout the microvasculature.
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Objective: To evaluate whether the concentration of serum lactate during the diagnosis of postpartum hemorrhage (bleeding ≥500 mL during labor or ≥1000 mL during cesarean delivery) predicts severe hemorrhage (SPPH; blood loss ≥1500 mL at end of labor or in the following 24 hours). Methods: A prospective cohort pilot study was conducted of women with a vaginal or cesarean delivery from February 2018 to March 2019 who presented with bleeding ≥500 mL measured by the gravimetric method in a reference hospital in San Luis Potosi, Mexico. Venous blood samples were taken for analysis of serum lactate. A receiver operating characteristic curve determined the serum lactate threshold value for SPPH and χ2 test assessed the difference in serum lactate elevation between SPPH and non-SPPH groups. Lastly, the prognostic capacity between the thresholds was compared. Results: SPPH developed in 43.33% of the 30 women in the study group. The best prognostic threshold was 2.68 mmol/L of serum lactate (odds ratio [OR] 17.88, 95% confidence interval [CI] 2.7-16.8, P<0.001); sensitivity was 0.85 (95% CI 0.55-0.98); specificity was 0.76 (95% CI 0.50-0.93). Conclusion: Serum lactate may be a useful prognostic marker for SPPH, more studies are needed to validate these findings.
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The advent of large‐scale veterinary blood banks has made the practice of high‐quality transfusion medicine possible by increasing availability of blood components. Strict adherence to blood collection, processing, and storage guidelines is essential to providing safe and effective transfusions. This chapter details the currently accepted blend of human protocol and veterinary modifications where necessary for the collection, processing, and storage of canine and feline blood components. Leukoreduction, or leukodepletion, is the process of removing residual white blood cell from transfusion components aimed at reducing transfusion‐induced inflammatory responses. Irradiation, ultraviolet illumination, and photochemical treatment of blood components may be used to decrease alloimmunization, graft‐versus‐host disease, and pathogen contamination. A flowchart for the separation of fresh whole blood by centrifugation is presented. Properly collected blood is anticipated to have a low level of bacterial contamination.
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