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Plasma Volume (plasma + volume)
Terms modified by Plasma Volume Selected AbstractsMeasurement of blood volume in the elasmobranch fish Scyliorhinus canicula following acute and long-term salinity transfersJOURNAL OF FISH BIOLOGY, Issue 6 2008J. P. Good A technique using 51chromium-labelled erythrocytes was used to measure blood volume in Scyliorhinus canicula following long-term and acute salinity transfers. Basal whole-blood volume was 5·6 ± 0·2 ml 100 g,1 (mean ±s.e.), this increased (6·3 ± 0·2 ml 100 g,1) following +14 day acclimation to 80% sea water (SW) and decreased (4·6 ± 0·2 ml 100 g,1) following acclimation to 120% SW. These changes were shown to be primarily due to changes in plasma volume, with no significant changes in extrapolated red-cell volume being demonstrated. Blood volume was also measured in the same animals during 10 h acute transfer to 100% SW. Plasma volume in S. canicula during acclimation from 80% SW was significantly reduced (4·5 ± 0·3 ml 100 g,1) after 6 h of transfer to 100% SW. Blood volume in animals during acclimation from 120% SW was significantly increased (4·8 ± 0·2 ml 100 g,1) after 4 h of acute transfer. The osmoregulatory implications of these different timeframes during hyposaline and hypersaline transfer are discussed, along with the importance of this in vivo technique as context for in vitro studies with haemo-dynamic stimuli. [source] MRI tumor characterization using Gd-GlyMe-DOTA-perfluorooctyl-mannose-conjugate (Gadofluorine MÔ), a protein-avid contrast agentCONTRAST MEDIA & MOLECULAR IMAGING, Issue 3 2006Hans-Jürgen Raatschen Abstract The rationale and objectives were to define the MRI tumor-characterizing potential of a new protein-avid contrast agent, Gd-GlyMe-DOTA-perfluorooctyl-mannose-conjugate (Gadofluorine MÔ; Schering AG, Berlin, Germany) in a chemically induced tumor model of varying malignancy. Because of the tendency for this agent to form large micelles in water and to bind strongly to hydrophobic sites on proteins, it was hypothesized that patterns of dynamic tumor enhancement could be used to differentiate benign from malignant lesions, to grade the severity of malignancies and to define areas of tumor necrosis. Gadofluorine M, 0.05,mmol,Gd,kg,1, was administered intravenously to 28 anesthetized rats that had developed over 10 months mammary tumors of varying degrees of malignancy as a consequence of intraperitoneal administration of N -ethyl- N -nitrosourea (ENU), 45,250,mg,kg,1. These tumors ranged histologically from benign fibroadenomas to highly undifferentiated adenocarcinomas. Dynamic enhancement data were analyzed kinetically using a two-compartment tumor model to generate estimates of fractional plasma volume (fPV), apparent fractional extracellular volume (fEV*) and an endothelial transfer coefficient (KPS) for this contrast agent. Tumors were examined microscopically for tumor type, degree of malignancy (Scarff,Bloom,Richardson score) and location of necrosis. Eighteen tumor-bearing rats were successfully imaged. MRI data showed an immediate strong and gradually increasing tumor enhancement. KPS and fEV*, but not fPV obtained from tumors correlated significantly (p,<,0.05) with the SBR tumor grade, r,=,0.65 and 0.56, respectively. Estimates for KPS and fEV* but not fPV were significantly lower in a group consisting of benign and low-grade malignant tumors compared with the group of less-differentiated high-grade tumors (1.61,±,0.64 vs 3.37,±,1.49, p,<,0.01; 0.45,±,0.17 vs 0.78,±,0.24, p,<,0.01; and 0.076,±,0.048 vs 0.121,±,0.088, p,=,0.24, respectively). It is concluded that the protein-avid MRI contrast agent Gadofluorine M enhances tumors of varying malignancy depending on the tumor grade, higher contrast agent accumulation for more malignant lesions. The results show potential utility for differentiating benign and low-grade malignant lesions from high-grade cancers. Copyright © 2006 John Wiley & Sons, Ltd. [source] Dielectric Characteristics for Radio Frequency Waves in a Laboratory Dipole PlasmaCONTRIBUTIONS TO PLASMA PHYSICS, Issue 4 2006N. I. Grishanov Abstract Transverse and parallel dielectric permittivity elements have been derived for radio frequency waves in a laboratory dipole magnetic field plasma. Vlasov equation is resolved for both the trapped and untrapped particles as a boundary value problem to define their separate contributions to the dielectric tensor components. To estimate the wave power absorbed in the plasma volume the perturbed electric field and current density components are decomposed in a Fourier series over the poloidal angle. In this case, the dielectric characteristics can be analyzed independently of the solution of the Maxwell's equations. As usual, imaginary part of the parallel permittivity elements is necessary to estimate the electron Landau damping of radio frequency waves, whereas imaginary part of the transverse permittivity elements is important to estimate the wave dissipation by the cyclotron resonances. Computations of the imaginary part of the parallel permittivity elements are carried out in a wide range of the wave frequencies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effects of immersion water temperature on whole-body fluid distribution in humansACTA PHYSIOLOGICA, Issue 1 2004J. M. Stocks Abstract Aim:, In this study, we quantified acute changes in the intracellular and extracellular fluid compartments during upright neutral- and cold-water immersion. We hypothesized that, during short-term cold immersion, fluid shifts would be wholly restricted to the extracellular space. Methods:, Seven males were immersed 30 days apart: control (33.3 ° SD 0.6 °C); and cold (18.1 ° SD 0.3 °C). Posture was controlled for 4 h prior to a 60-min seated immersion. Results:, Significant reductions in terminal oesophageal (36.9 ° ± 0.1 °,36.3 ° ± 0.1 °C) and mean skin temperatures (30.3 ° ± 0.3 °,23.0 ° ± 0.3 °C) were observed during the cold, but not the control immersion. Both immersions elicited a reduction in intracellular fluid [20.17 ± 6.02 mL kg,1 (control) vs. 22.72 ± 9.90 mL kg,1], while total body water (TBW) remained stable. However, significant plasma volume (PV) divergence was apparent between the trials at 60 min [12.5 ± 1.0% (control) vs. 6.1 ± 3.1%; P < 0.05], along with a significant haemodilution in the control state (P < 0.05). Plasma atrial natriuretic peptide concentration increased from 18.0 ± 1.6 to 58.7 ± 15.1 ng L,1 (P < 0.05) during cold immersion, consistent with its role in PV regulation. We observed that, regardless of the direction of the PV change, both upright immersions elicited reductions in intracellular fluid. Conclusion:, These observations have two implications. First, one cannot assume that PV changes reflect those of the entire extracellular compartment. Second, since immersion also increases interstitial fluid pressure, fluid leaving the interstitium must have been rapidly replaced by intracellular water. [source] Lactoferrin and anti-lactoferrin antibodies: Effects of ironloading of lactoferrin on albumin extravasation in different tissues in ratsACTA PHYSIOLOGICA, Issue 1 2000Erga Lactoferrin is a cationic iron-binding protein, which is released from activated neutrophils in concert with reactive oxygen species. In vitro, lactoferrin has both anti- and proinflammatory effects; many of them dependent on iron-binding. In vivo, only iron-free lactoferrin reduced inflammatory hyperpermeability in the lung. We therefore examined whether 1 mg iron-free (Apo-Lf) or iron-saturated lactoferrin (Holo-Lf) alone or followed by anti-lactoferrin antibodies (aLf) affected permeability evaluated by extravasation of radiolabelled bovine serum albumin (CBSA) in different tissues of anaesthetized rats. Fifteen minutes after i.v. injection of Lf, aLf or saline was given and circulatory arrest was induced 20 min thereafter. Measurements were performed in control, after Apo-Lf, Holo-Lf, Apo-Lf + aLf, Holo-Lf + aLf and aLf alone (n=6,8 in each group). No intergroup differences were found for plasma volume and haematocrit at the start and end of the 37 min extravasation period or for total tissue water in any of the six different tissues studied, excluding larger transcapillary fluid shifts. However, increases in CBSA were seen without differences in tissue intravascular volume. Iron-free lactoferrin and aLf alone did not change CBSA significantly. Iron-saturated lactoferrin significantly increased CBSA in skin (neck), trachea and left ventricle of the heart to 249 ± 9, 284 ± 16 and 160 ± 7% of control, respectively. When followed by aLf, both Apo- and Holo-Lf increased CBSA significantly in four and five of the tissues studied, respectively. However, no significant effect was seen for Holo-Lf + aLf compared with Holo-Lf alone. In conclusion, iron-saturated, but not iron-free lactoferrin increased CBSA, whereas antilactoferrin increased CBSA compared with lactoferrin alone only when following iron-free lactoferrin. [source] No effect of venoconstrictive thigh cuffs on orthostatic hypotension induced by head-down bed restACTA PHYSIOLOGICA, Issue 2 2000M.-A. Custaud Orthostatic intolerance (OI) is the most serious symptom of cardiovascular deconditioning induced by head-down bed rest or weightlessness. Wearing venoconstrictive thigh cuffs is an empirical countermeasure used by Russian cosmonauts to limit the shift of fluid from the lower part of the body to the cardio-cephalic region. Our aim was to determine whether or not thigh cuffs help to prevent orthostatic hypotension induced by head-down bed rest. We studied the effect of thigh cuffs on eight healthy men. The cuffs were worn during the day for 7 days of head-down bed rest. We measured: orthostatic tolerance (stand tests and lower body negative pressure tests), plasma volume (Evans blue dilution), autonomic influences (plasma noradrenaline) and baroreflex sensitivity (spontaneous baroreflex slope). Thigh cuffs limited the loss of plasma volume (thigh cuffs: ,201 ± 37 mL vs. control: ,345 ± 42 mL, P < 0.05), the degree of tachycardia and reduction in the spontaneous baroreflex sensitivity induced by head-down bed rest. However, the impact of thigh cuffs was not sufficient to prevent OI (thigh cuffs: 7.0 min of standing time vs. control: 7.1 min). Decrease in absolute plasma volume and in baroreflex sensitivity are known to be important factors in the aetiology of OI induced by head-down bed rest. However, dealing with these factors, using thigh cuffs for example, is not sufficient to prevent OI. Other factors such as venous compliance, microcirculatory changes, peripheral arterial vasoconstriction and vestibular afferents must also be considered. [source] Hydration of exercised Standardbred racehorses assessed noninvasively using multi-frequency bioelectrical impedance analysisEQUINE VETERINARY JOURNAL, Issue S36 2006A. WALLER Summary Reasons for performing study: In human and animal clinical practice, multi-frequency bioelectrical impedance analysis (MF-BIA) is increasingly used as a diagnostic tool to assess hydration of intra-and extracellular fluid compartments. Accurate determination of changes in hydration status within individuals over time has remained problematic due to the requirement for complete impedance-frequency relationships at the time points of interest. Objectives: To use MF-BIA in 13 Standardbred racehorses and 7 ,endurance' research horses to determine if MF-BIA could be used to track changes in total body water (TBW), intracellular fluid volume (ICFV) and extracellular fluid volume (ECFV) resulting from exercise. Methods: Jugular venous blood was sampled at rest and for 2,13 h following exercise. TBW, ECFV and plasma volume (PV) were measured at rest using indicator dilution techniques (D2O, thiocyanate and Evans Blue, respectively). TBW, ECFV, ICFV and PV were correlated to impedance measures and predictive equations used to determine hydration status from MF-BIA measures. Results: TBW loss continued throughout the recovery period, and was primarily borne by the ECF compartment at 90 min of recovery. Conclusions: MF-BIA predictions of compartmental hydration status were significantly correlated to measured/calculated decreases in these compartments. Potential relevance: Practical applications for MF-BIA in horses include monitoring of hydration status during transport and competition, assessment of body compostion, clinical health assessment and critical care management. [source] Pharmacokinetics of factors IX, recombinant human activated factor VII and factor XIIIHAEMOPHILIA, Issue 2006M.-C. POON Summary., There is now a volume of literature on the pharmacokinetics (PK) of coagulation factor concentrates, although the majority is on factor VIII (FVIII) and factor IX (FIX). PK of FIX and FVIII are different with FIX having a larger volume of distribution (Vdss), higher elimination clearance (CL), longer mean resident time (MRT) and longer terminal half-life (T1/2,,). Factor IX in vivo recovery (IVR) is also much shorter possibly due to reversible binding of FIX to the endothelium and possibly to platelets. There is considerable FIX PK variability between products (particularly between plasma-derived FIX and recombinant FIX), and between individuals. Important inter-individual factors leading to PK variability include age and body weight because plasma volume as a fraction of body weight decreases with increasing weight and hence age. Thus, IVR increases with body weight and hence age and is consequently lower in children than in adults. Absolute Vdss and CL increase linearly with body weight and age in children and adolescents, becoming stable in adults with more stable weight. Inter-individual variability also likely applies to other clotting factors, particularly to recombinant activated FVII (rFVIIa) but likely also to the less well studied factor XIII (FXIII). The former is known to have an extremely short T1/2,,, large Vdss, high CL, short MRT, whereas the latter has an extremely long T1/2,,, large Vdss, short CL and long MRT. Both are discussed in this article. Understanding of PK of specific clotting factors in individual patients is important in order to make decisions regarding appropriate dosage and dosage intervals to treat patients, and to allow by means of computer modelling the determination of dosage to achieve target trough level at various dosing intervals for patients undergoing prophylaxis. [source] Cardiovascular dialysis instability and convective therapiesHEMODIALYSIS INTERNATIONAL, Issue 2006Antonio SANTORO Abstract Acute hypotension is a frequent hemodialysis complication. Intratreatment vascular instability is a multifactorial process in which procedure-related and patient-related factors may influence the decrease in plasma volume and induce an impairment of cardiovascular regulatory mechanisms. Identification of the most susceptible patients and of the various risk factors may contribute to significantly improve cardiovascular stability during dialysis. In some high-risk patients, monitoring and biofeedback of the various hemodynamic variables, together with an extensive use of convection, can prevent the appearance of symptomatic hypotension and help in averting its onset. [source] Norepinephrine causes a pressure-dependent plasma volume decrease in clinical vasodilatory shockACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2010A. NYGREN Background: Recent experimental studies have shown that a norepinephrine-induced increase in blood pressure induces a loss of plasma volume, particularly under increased microvascular permeability. We studied the effects of norepinephrine-induced variations in the mean arterial pressure (MAP) on plasma volume changes and systemic haemodynamics in patients with vasodilatory shock. Methods: Twenty-one mechanically ventilated patients who required norepinephrine to maintain MAP ,70 mmHg because of septic/postcardiotomy vasodilatory shock were included. The norepinephrine dose was randomly titrated to target MAPs of 60, 75 and 90 mmHg. At each target MAP, data on systemic haemodynamics, haematocrit, arterial and mixed venous oxygen content and urine flow urine were measured. Changes in the plasma volume were calculated as 100 × (Hctpre/Hctpost,1)/ (1,Hctpre), where Hctpre and Hctpost are haematocrits before and after intervention. Results: Norepinephrine doses to obtain target MAPs of 60, 75 and 90 mmHg were 0.20±0.18, 0.29±0.18 and 0.42±0.31 ,g/kg/min, respectively. From 60 to 90 mmHg, increases in the cardiac index (15%), systemic oxygen delivery index (25%), central venous pressure (CVP) (20%) and pulmonary artery occlusion pressure (33%) were seen, while the intrapulmonary shunt fraction was unaffected by norepinehrine. Plasma volume decreased by 6.5% and 9.4% (P<0.0001) when blood pressure was increased from 60 to 75 and 90 mmHg, respectively. MAP (P<0.02) independently predicted the decrease in plasma volume with norepinephrine but not CVP (P=0.19), cardiac index (P=0.73), norepinephrine dose (P=0.58) or urine flow (P=0.64). Conclusions: Norepinephrine causes a pressure-dependent decrease in the plasma volume in patients with vasodilatory shock most likely caused by transcapillary fluid extravasation. [source] Comparative study on the regulation of body fluids and mammary circulation at different stages of lactation in crossbred Holstein cattle feeding on different types of roughageJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 2 2000N. Chaiyabutr Summary The present study was carried out to evaluate the effect of prolonged feeding of urea-treated rice straw, compared with feeding of hay, on the regulation of body fluids, milk yield and mammary circulation at early lactation (30 days postpartum), mid-lactation (120 days postpartum) and late lactation (210 days postpartum) in crossbred Holstein Friesians. Sixteen first lactating crossbred Holstein Friesians (HF), consisting of eight animals of two breed types, 87.5%HF and 50%HF, were selected and each breed was randomly allocated into two groups. Each group, consisting of four animals from the same breed, was fed either 5% urea-treated rice straw or pangola hay (Digitaria decumbens) as the source of roughage in combination with a similar concentrate throughout the experiments. During the course of lactation there were no significant differences in body weight, heart rate, mean arterial blood pressure, plasma osmolality, plasma volume and blood volume among groups of 87.5%HF animals and 50%HF animals fed either hay or urea-treated rice straw. Water turnover rate, total body water space and total body water as a percentage of body weight of 50%HF animals were significantly higher than those of 87.5%HF animals fed either hay or urea-treated rice straw. The packed cell volume was significantly higher in all lactating periods of both groups of 50%HF animals in comparison with 87.5%HF animals. The ratio of DM intake to milk production for 87.5%HF animals fed either hay or urea-treated rice straw was significantly lower than that of 50%HF animals in early lactation. The udder blood flow and milk secretion of 87.5%HF were significantly higher in early lactation and markedly declined when lactation advanced in comparison with those of 50%HF animals fed either hay or urea-treated rice straw. The ratio of mammary blood flow to milk yield for all groups was in a similar range during early lactation although it significantly increased in mid- and late lactation for both groups of 87.5%HF animals. From these results it can be concluded that both 50%HF and 87.5%HF animals feeding on urea-treated rice straw as a roughage source do not show any undernutritional effects in comparison with those fed with hay during the course of lactation. The physiological response differences between breeds are that 87.5%HF animals, which have a genetic makeup closer to the exotic bos taurus breed and a high milk yield, show a poor adjustment to the tropical environment and poorer lactation persistency in comparison with 50%HF animals. [source] Starch and albumin mixture as replacement fluid in therapeutic plasma exchange is safe and effectiveJOURNAL OF CLINICAL APHERESIS, Issue 5 2008Gladys P. Agreda-Vásquez Abstract Therapeutic plasma exchange (TPE) is an effective treatment in Myasthenia gravis (MG) and Guillain-Barré syndrome (GBS) and 5% human albumin is the replacement fluid of choice; however, it is expensive. More recently, it has been suggested that starch is a safe and cheaper choice to human albumin. Objective: To evaluate our 5-year experience using 3% hydroxyethyl starch (HES) and 5% human albumin mixture, as replacement fluid in TPE for these diseases. Materials and methods: Retrospective study carried out from January 2001 through September 2006. We included those patients with MG and GBS undergoing TPE. We analyzed clinical outcome (CO) and adverse events (AE) and our results were compared with a previous study which included similar patients undergoing TPE using just 5% human albumin. Results: Thirty-one procedures were carried out in 26 patients, a total of 147 TPE sessions. In the group of MG we had 57% complete responses (CR) and 86% overall response (OR) while in the group of GBS we had 40% CR and 60% OR. When we analyzed our CO with the previous study no statistical differences were found. Mean processed plasma volume (PPV) was 4.2 in MG and 5.5 in GBS. Twenty patients had AE, being hypotension and catheter dysfunction the most frequent ones, while tachycardia, hypertension and paresthesias were statistically more frequent in the HES/albumin group. Conclusions: TPE with a mixture of 3% HES and 5% human albumin is as effective and safe as 5% human albumin alone for patients with these diseases. J. Clin. Apheresis, 2008. © 2008 Wiley-Liss, Inc. [source] Factors affecting platelet yield and their impact on the platelet increment of patients receiving single donor PLT transfusion,JOURNAL OF CLINICAL APHERESIS, Issue 1 2007A. Aboul Enein Abstract The aim of this study was to analyze the impact of various donor and machine parameters on PLT yield in 127 PLT apheresis procedures, to optimize PLT yield achieving clinical and economic advantages. One hundred and twenty-seven apheresis procedures were analyzed. Age, gender, volume processed, Hb, and PLT precounts were included as donor predicting variables. AC infusion rate, processing time, and plasma volume collected with PLTs were assessed as machine parameters. We evaluated the post-transfusion effectiveness in 23 patients with thrombocytopenia, studying the effect of PLT dose, ABO group, and PLT storage time. Females gave higher yields, compared to males, P < 0.01. PLT yield correlated positively with PLT precount (r = 0.512), and TBV (r = 0.404), and negatively with donor preapheresis Hb (r = ,0.306). Processing time and AC infusion rate had a positive impact on PLT yield. Post-apheresis decrease in PLT count was 53.6 ± 26.3 × 1011. Donors with Hb , 12 g/dl, donated safely. Most of the complications were citrate related (13.4% of all procedures). PLT increments in transfused patients correlated positively with the number of units transfused (r = 0.41), and negatively with PLT storage days (r = ,0.342). PLT increments in patients receiving ABO-compatible PLTs were 75% higher, compared to the increments in patients receiving incompatible PLTs. PLT count and volume processed were the main predictors of PLT yield. Increasing the processing time, the AC infusion rate, or the volume of plasma obtained with PLTs can increase PLT yields. High PLT dose, short storage time, as well as ABO compatibility should be considered during PLT transfusion. J. Clin. Apheresis, 2007 © 2007 Wiley-Liss, Inc. [source] Calcium Channel Blocker-Related Peripheral Edema: Can It Be Resolved?JOURNAL OF CLINICAL HYPERTENSION, Issue 4 2003Domenic A. Sica MD Calcium channel blocker (CCB)-related edema is quite common in clinical practice and can effectively deter a clinician from continued prescription of these drugs. Its etiology relates to a decrease in arteriolar resistance that goes unmatched in the venous circulation. This disproportionate change in resistance increases hydrostatic pressures in the precapillary circulation and permits fluid shifts into the interstitial compartment. CCB-related edema is more common in women and relates to upright posture, age, and the choice and dose of the CCB. Once present it can be slow to resolve without intervention. A number of strategies exist to treat CCB-related edema, including switching CCB classes, reducing the dosage, and/or adding a known venodilator such as a nitrate, an angiotensin-converting enzyme inhibitor, or an angiotensin-receptor blocker to the treatment regimen. Angiotensin-converting enzyme inhibitors have been best studied in this regard. Diuretics may alter the edema state somewhat, but at the expense of further reducing plasma volume. Traditional measures such as limiting the amount of time that a patient is upright and/or considering use of graduated compression stockings are useful adjunctive therapies. Discontinuing the CCB and switching to an alternative antihypertensive therapy will resolve the edema. [source] Measurement of blood volume in the elasmobranch fish Scyliorhinus canicula following acute and long-term salinity transfersJOURNAL OF FISH BIOLOGY, Issue 6 2008J. P. Good A technique using 51chromium-labelled erythrocytes was used to measure blood volume in Scyliorhinus canicula following long-term and acute salinity transfers. Basal whole-blood volume was 5·6 ± 0·2 ml 100 g,1 (mean ±s.e.), this increased (6·3 ± 0·2 ml 100 g,1) following +14 day acclimation to 80% sea water (SW) and decreased (4·6 ± 0·2 ml 100 g,1) following acclimation to 120% SW. These changes were shown to be primarily due to changes in plasma volume, with no significant changes in extrapolated red-cell volume being demonstrated. Blood volume was also measured in the same animals during 10 h acute transfer to 100% SW. Plasma volume in S. canicula during acclimation from 80% SW was significantly reduced (4·5 ± 0·3 ml 100 g,1) after 6 h of transfer to 100% SW. Blood volume in animals during acclimation from 120% SW was significantly increased (4·8 ± 0·2 ml 100 g,1) after 4 h of acute transfer. The osmoregulatory implications of these different timeframes during hyposaline and hypersaline transfer are discussed, along with the importance of this in vivo technique as context for in vitro studies with haemo-dynamic stimuli. [source] Intra-operative colloid administration increases the clearance of a post-operative fluid loadACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2009T. BORUP Background: It is unknown whether an intra-operative colloid infusion alters the dynamics of a crystalloid load administered post-operatively. Methods: Ten patients received 12.5 ml/kg of Ringer's lactate over 30 min 1,3 days before and 4 h after laparoscopic cholecystectomy, during which 10 ml/kg of a colloid solution, hydroxyethylstarch (HES 130/0.4), was infused. The total body clearance of the pre- and post-operative test infusions was taken as the ratio between the urinary excretion and the Hb-derived dilution of venous plasma over 150 min. The plasma clearance of the infused fluid was calculated using volume kinetics based on the plasma dilution alone. The pre-operative plasma clearance was compared with the post-operative plasma clearance and patients served as their own control. Results: The urinary excretion averaged 350 ml for the pre-operative infusion and 612 ml post-operatively, which corresponds to 46% and 68% of the pre- and post-operative infusions, respectively. The total body clearance of the crystalloid fluid was 30 ml/min before surgery and 124 ml/min after surgery (P<0.01). The plasma clearance, as obtained from the plasma dilution alone, was 28 and 412 ml/min, respectively. The maximal increase in plasma volume was 410 ml pre-operatively vs. 220 ml post-operatively. Conclusions: Infusion of a colloid solution in combination with a crystalloid during laparoscopic cholecystectomy increased the plasma clearance of a post-operative crystalloid infusion. [source] Prediction of pharmacokinetics prior to in vivo studies.JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Abstract In drug discovery and nonclinical development the volume of distribution at steady state (Vss) of each novel drug candidate is commonly determined under in vivo conditions. Therefore, it is of interest to predict Vss without conducting in vivo studies. The traditional description of Vss corresponds to the sum of the products of each tissue:plasma partition coefficient (Pt:p) and the respective tissue volume in addition to the plasma volume. Because data on volumes of tissues and plasma are available in the literature for mammals, the other input parameters needed to estimate Vss are the Pt:p's, which can potentially be predicted with established tissue composition-based equations. In vitro data on drug lipophilicity and plasma protein binding are the input parameters used in these equations. Such a mechanism-based approach would be particularly useful to provide first-cut estimates of Vss prior to any in vivo studies and to explore potential unexpected deviations between sets of predicted and in vivoVss data, when the in vivo data become available during the drug development process. The objective of the present study was to use tissue composition-based equations to predict rat and human Vss prior to in vivo studies for 123 structurally unrelated compounds (acids, bases, and neutrals). The predicted data were compared with in vivo data obtained from the literature or at Roche. Overall, the average ratio of predicted-to-experimental rat and human Vss values was 1.06 (SD,=,0.817, r,=,0.78, n,=,147). In fact, 80% of all predicted values were within a factor of two of the corresponding experimental values. The drugs can therefore be separated into two groups. The first group contains 98 drugs for which the predicted Vss were within a factor of two of those experimentally determined (average ratio of 1.01, SD,=,0.39, r,=,0.93, n,=,118), and the second group includes 25 other drugs for which the predicted and experimental Vss differ by a factor larger than two (average ratio of 1.32, SD,=,1.74, r,=,0.42, n,=,29). Thus, additional relevant distribution processes were neglected in predicting Vss of drugs of the second group. This was true especially in the case of some cationic-amphiphilic bases. The present study is the first attempt to develop and validate a mechanistic distribution model for predicting rat and human Vss of drugs prior to in vivo studies. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:129,156, 2002 [source] Blood volume is normal after pre-operative overnight fastingACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2008M. JACOB Background: Pre-operative fasting is assumed to cause a deficit in intravascular blood volume (BV), as a result of ongoing urine production and insensible perspiration. Standard regimes consist of volume loading prior or simultaneous to any anaesthetic procedure to minimise the risk of hypotension. However, fluid overload in the context of major abdominal surgery has been shown to deteriorate patient outcome. Our study aimed to quantify total intravascular BV after fasting by direct measurements and to compare it with calculated normal values in comparable non-fasted patients. Methods: After 10 h of fasting, total plasma volume (PV) and red cell volume (RCV) were measured via the double-label technique (indocyanine green dilution and erythrocytes labelled with fluorescein, respectively) following induction of general anaesthesia in 53 gynaecological patients suffering from malignoma of the cervix. The corresponding normal values were calculated individually from age, body height and body weight. Results: Measured BV, RCV and PV after fasting were 4123±589, 1244±196 and 2879±496 ml, respectively. The differences to the corresponding calculated normal values were not significant (3882±366, 1474±134 and 2413±232 ml, respectively). The measured haematocrit reflected a slight anaemic state (0.35±0.03). Conclusion: Our data suggest that even after prolonged pre-operative fasting, cardio-pulmonary healthy patients remain intravascularly normovolaemic. Therefore, hypotension associated with induction of general or neuraxial anaesthesia should perhaps be treated with moderate doses of vasopressors rather than with undifferentiated volume loading. [source] Clinical Pharmacokinetics of the PDT Photosensitizers Porfimer Sodium (Photofrin), 2-[1-Hexyloxyethyl]-2-Devinyl Pyropheophorbide-a (Photochlor) and 5-ALA-Induced Protoporphyrin IXLASERS IN SURGERY AND MEDICINE, Issue 5 2006David A. Bellnier PhD Abstract Background and Objectives Photodynamic therapy (PDT) uses a photosensitizer activated by light, in an oxygen-rich environment, to destroy malignant tumors. Clinical trials of PDT at Roswell Park Cancer Institute (RPCI) use the photosensitizers Photofrin, Photochlor, and 5-ALA-induced protoporphyrin IX (PpIX). In some studies the concentrations of photosensitizer in blood, and occasionally in tumor tissue, were obtained. Pharmacokinetic (PK) data from these individual studies were pooled and analyzed. This is the first published review to compare head-to-head the PK of Photofrin and Photochlor. Study Design/Materials and Methods Blood and tissue specimens were obtained from patients undergoing PDT at RPCI. Concentrations of Photofrin, Photochlor, and PpIX were measured using fluorescence analysis. A non-linear mixed effects modeling approach was used to analyze the PK data for Photochlor (up to 4 days post-infusion; two-compartment model) and a simpler multipatient-data-pooling approach was used to model PK data for both Photofrin and Photochlor (at least 150 days post-infusion; three-compartment models). Physiological parameters were standardized to correspond to a standard (70 kg; 1.818 m2 surface area) man to facilitate comparisons between Photofrin and Photochlor. Results Serum concentration-time profiles obtained for Photofrin and Photochlor showed long circulating half-lives, where both sensitizers could be found more than 3 months after intravenous infusion; however, estimated plasma clearances (standard man) were markedly smaller for Photofrin (25.8 ml/hour) than for Photochlor (84.2 ml/hour). Volumes of distribution of the central compartment (standard man) for both Photofrin and Photochlor were about the size (3.14 L, 4.29 L, respectively) of plasma volume, implying that both photosensitizers are almost 100% bound to serum components. Circulating levels of PpIX were generally quite low, falling below the level of instrument sensitivity within a few days after topical application of 5-ALA. Conclusion We have modeled the PK of Photochlor and Photofrin. PK parameter estimates may, in part, explain the relatively long skin photosensitivity attributed to Photofrin but not Photochlor. Due to the potential impact and limited experimental PK data in the PDT field further clinical studies of photosensitizer kinetics in tumor and normal tissues are warranted. Lasers Surg. Med. © 2006 Wiley-Liss, Inc. [source] Fluid resuscitation from severe hemorrhagic shock using diaspirin cross-linked hemoglobin fails to improve pancreatic and renal perfusionACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2004A. Pape Background:, Fluid resuscitation from hemorrhagic shock is intended to abolish microcirculatory disorders and to restore adequate tissue oxygenation. Diaspirin cross-linked hemoglobin (DCLHb) is a hemoglobin-based oxygen carrier (HBOC) with vasoconstrictive properties. Therefore, fluid resuscitation from severe hemorrhagic shock using DCLHb was expected to improve perfusion pressure and tissue perfusion of kidneys and pancreas. Methods:, In 20 anesthetized domestic pigs with an experimentally induced coronary stenosis, shock (mean arterial pressure 45 mmHg) was induced by controlled withdrawal of blood and maintained for 60 min. Fluid resuscitation (replacement of the plasma volume withdrawn during hemorrhage) was performed with either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). Completion of resuscitation was followed by a 60-min observation period. Regional blood flow to the kidneys and the pancreas was measured by use of the radioactive microspheres method at baseline, after shock and 60 min after fluid resuscitation. Results:, All animals (10/10) resuscitated with DCLHb survived the 60-min observation period, while 5/10 control animals died within 20 min due to persisting subendocardial ischemia. In contrast to HSA survivors, pancreas and kidneys of DCLHb-treated animals revealed lower total and regional organ perfusion and regional oxygen delivery. Renal and pancreatic blood flow heterogeneity was higher in the DCLHb group. Conclusion:, DCLHb-induced vasoconstriction afforded superior myocardial perfusion, but impaired regional perfusion of the kidneys and the pancreas. [source] Glycocalyx volume: a critical review of tracer dilution methods for its measurementMICROCIRCULATION, Issue 3 2009CHARLES. ABSTRACT A clinical measure of endothelial glycocalyx structure would have great potential importance, because lesions of the glycocalyx may be the first changes to occur in diabetes and in a wide range of vascular diseases. A method recently described by Nieuwdorp et al. for estimating the volume of the luminal glycocalyx of the entire human vascular system would seem to be the first attempt to develop a measure of this kind. It is based on the tracer dilution principle, and this review considers the principles and conditions that underlie this method and the extent to which the conditions appear to have been fulfilled in this case. Our analysis raises two questions about 1) the estimation of the concentration of the tracer (dextran 40) at zero time and 2) the estimation of plasma volume, both of which can be answered by changes in experimental protocol. A third question, concerning the partition coefficient of the tracer between plasma and the fluid within the glycocalyx, cannot be answered at the present time, and until it has been resolved, glycocalyx volume cannot be estimated from the dilution of a macromolecular tracer. [source] Physiological and performance effects of glycerol hyperhydration and rehydrationNUTRITION REVIEWS, Issue 12 2009Simon P Van Rosendal Studies have shown that beverages containing glycerol can enhance and maintain hydration status and may improve endurance exercise performance by attenuating adverse physiological changes associated with dehydration. Improvements to performance include increased endurance time to exhaustion by up to 24%, or a 5% increase in power or work. However, some studies have found no performance benefits during either prolonged exercise or specific skill and agility tests. In studies that have shown benefits, the improvements have been associated with thermoregulatory and cardiovascular changes. These include increased plasma volume and sweat rates, as well as reduced core temperature and ratings of perceived exertion. In a very small number of subjects, glycerol consumption has been associated with side-effects including nausea, gastrointestinal discomfort, dizziness, and headaches. In summary, while glycerol and fluid ingestion results in hyperhydration, the documented benefits to exercise performance remain inconsistent. [source] First and second-trimester biochemical markers of chromosomal anomalies and their relationship to maternal haemoglobin levelsPRENATAL DIAGNOSIS, Issue 8 2005N. J. Cowans Abstract Objective To evaluate a previous hypothesis that maternal serum biochemical markers used in the assessment of Down syndrome risk are related to maternal haemoglobin concentrations. Methods A series of 1306 second-trimester prenatal screening records were retrieved including information on marker levels (AFP and f,hCG MoMs), Down's risk, a priori age risk, maternal weight and maternal height. Each individual record was merged with data from haematological investigations on samples collected on the same day. A similar series of 1688 first-trimester screening records were also retrieved including the maker levels for PAPP-A, and f,hCG MoMs were merged with data from haematological investigations carried out on the same day. The two groups were categorised according to their haemoglobin levels; anaemic (less than 11.0 g/dL in first trimester and 10.5 g/dL in the second trimester), high haemoglobin (greater than 14.0 g/dL and 13.2 g/dL) or normal (between these ranges). An analysis was made of marker levels in the various groups before and after correction for ethnicity and of the screen-positive rate in the various groups. Using a formula based on maternal height and weight, variation of marker levels with plasma volume was assessed. Results In the first trimester, 12.6% of the pregnant population was anaemic and 1.6% had elevated haemoglobin levels. In the second trimester this was 12.7 and 3.9%. These figures varied considerably with ethnic origin, with Asian and Afro-Caribbean women being more anaemic than Caucasian women. Haemoglobin levels declined by 7% between the 11- and 21-week period. Maternal plasma volume (as calculated by a widely used maternal height and weight relationship) was not correlated with weight-corrected biochemical marker MoMs in either trimester. A weak but significant correlation of maternal plasma volume and haemoglobin concentration was observed. There was no significant correlation between biochemical marker MoMs and haemoglobin concentration. Although the proportion of pregnancies designated screen positive decreased as haemoglobin levels increased, this was paralleled by a decrease in the maternal age apriori risk. Conclusions There is no relationship between maternal haemoglobin levels and the levels of Down syndrome markers in either the first or second trimester. Biochemical marker levels do not need to be corrected for haemoglobin concentrations when used in screening for Down syndrome. Copyright © 2005 John Wiley & Sons, Ltd. [source] Influence of endogenous angiotensin II on control of sympathetic nerve activity in human dehydrationTHE JOURNAL OF PHYSIOLOGY, Issue 22 2009J. A. Rabbitts Arterial blood pressure can often fall too low during dehydration, leading to an increased incidence of orthostatic hypotension and syncope. Systemic sympathoexcitation and increases in volume regulatory hormones such as angiotensin II (AngII) may help to maintain arterial pressure in the face of decreased plasma volume. Our goals in the present study were to quantify muscle sympathetic nerve activity (MSNA) during dehydration (DEH), and to test the hypothesis that endogenous increases in AngII in DEH have a mechanistic role in DEH-associated sympathoexcitation. We studied 17 subjects on two separate study days: DEH induced by 24 h fluid restriction and a euhydrated (EUH) control day. MSNA was measured by microneurography at the peroneal nerve, and arterial blood pressure, electrocardiogram, and central venous pressure were also recorded continuously. Sequential nitroprusside and phenylephrine (modified Oxford test) were used to evaluate baroreflex control of MSNA. Losartan (angiotensin type 1 receptor (AT1) antagonist) was then administered and measurements were repeated. MSNA was elevated during DEH (42 ± 5 vs. EUH: 32 ± 4 bursts per 100 heartbeats, P= 0.02). Blockade of AT1 receptors partially reversed this change in MSNA during DEH while having no effect in the control EUH condition. The sensitivity of baroreflex control of MSNA was unchanged during DEH compared to EUH. We conclude that endogenous increases in AngII during DEH contribute to DEH-associated sympathoexcitation. [source] Erythropoietin effect on red cell and plasma volumeTHE JOURNAL OF PHYSIOLOGY, Issue 1 2008Dieter Böning No abstract is available for this article. [source] Modulation of body fluids and angiotensin II receptors in a rat model of intra-uterine growth restrictionTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005Sophie Bédard We previously reported that sodium restriction during pregnancy reduces plasma volume expansion and promotes intra-uterine growth restriction (IUGR) in rats while it activates the renin,angiotensin,aldosterone system (RAAS). In the present study, we proceeded to determine whether expression of the two angiotensin II (ANGII) receptor subtypes (AT1 and AT2) change in relation to maternal water,electrolyte homeostasis and fetal growth. To this end, pregnant (gestation day 15) and non-pregnant Sprague-Dawley rats were randomly assigned to two groups fed either normal, or Na+ -restricted diets for 7 days. At the end of the treatment period, plasma aldosterone and renin activity as well as plasma and urine electrolytes were measured. Determinations for AT1 and AT2 mRNA and protein were made by RNase protection assay and photoaffinity labelling, respectively, using a number of tissues implicated in volume regulation and fetal growth. In non-pregnant rats, Na+ restriction decreases Na+ excretion without altering plasma volume, plasma Na+ concentration or the expression of AT1 and AT2 mRNA or protein in the tissues examined. In normally fed pregnant rats when compared to non-pregnant controls, AT1 mRNA increases in the hypothalamus as well as pituitary and declines in uterine arteries, while AT1 protein decreases in the kidney and AT2 mRNA declines in the adrenal cortex. In pregnant rats, Na+ restriction induces a decrease in plasma Na+, an increase in plasma urea, as well as a decline in renal urea and creatinine clearance rates. Protein levels for both AT1 and AT2 in the pituitary and AT2 mRNA in the adrenal cortex are lower in the Na+ -restricted pregnant group when compared to normally fed pregnant animals. Na+ restriction also induces a decrease in AT1 protein in the placenta. In conclusion, these results suggest that pregnancy may increase sensitivity to Na+ depletion by the tissue-specific modulation of ANGII receptors. Finally, these receptors may be implicated in the IUGR response to low Na+. [source] PSA and body composition by dual X-Ray absorptiometry (DXA) in NHANESTHE PROSTATE, Issue 2 2010Jay H. Fowke Abstract BACKGROUND Obese men are at higher risk for advanced prostate cancer and have a poorer prognosis following treatment. Several studies also report that obese men have lower blood PSA levels, suggesting that obesity may be interfering with the ability to detect early-stage prostate cancer. METHODS Dual X-ray absorptiometry (DXA) is considered a gold-standard measurement of body composition. We investigated the association between PSA levels and body composition measured by DXA among 1,360 men participating in NHANES (2001,2004), a representative sample of the U.S. male population. RESULTS After controlling for age, race, and other factors, PSA concentration was ,15% lower for men with the highest level of total mass, lean mass, fat mass, trunk lean mass, and trunk fat mass (all P for trend <0.05). We then multiplied PSA concentration by estimated plasma volume to calculate the amount of PSA in circulation (i.e., PSA mass). Total body fat mass and fat mass located in the body trunk were not significantly associated with PSA mass, however, PSA mass was ,10,15% higher across low versus high categories of total body lean mass and bone mineral content (all P -trend <0.05). CONCLUSION Our results using DXA to measure body composition confirm that a greater body mass, not just fat mass, is associated with a lower PSA concentration. This is consistent with PSA hemodilution within men with a higher body mass index. The separate associations between measured lean and fat mass on calculated PSA mass require further investigation. Prostate 70: 120,125, 2010. ©2009 Wiley-Liss, Inc. [source] Obesity and screening PSA levels among men undergoing an annual physical examTHE PROSTATE, Issue 4 2008Andrew Rundle Abstract BACKGROUND Prior reports suggest that obesity is inversely associated with screening prostate-specific antigen (PSA) levels and may reduce screening sensitivity. METHODS We evaluated data on 10,623 men screened for prostate cancer during an annual physical examination program administered by EHE International, Inc., between 1/1/2004 and 6/30/2006. Of these, 3,623 men returned for additional physical exams during this period. We used multivariate linear regression analyses to determine whether higher BMI was inversely associated with PSA, and whether BMI, or change in BMI, was associated with change in PSA levels over time. We also developed a theoretical model for the effect of obesity on PSA levels in which increased plasma volume in the obese dilutes PSA levels. RESULTS After control for age and race/ethnicity, higher BMI was associated with lower PSA levels; men with a BMI ,40 had a geometric mean PSA level 0.14 ng/ml lower than men with a BMI <25 (P,<,0.001). Prospectively, BMI at initial screening and change in BMI over 2 years were not associated with change in PSA or PSA velocity. Our theoretical model accurately predicted observed PSA levels and suggests that a screening PSA of 4.0 ng/ml in normal weight and overweight men corresponds to 3.5 ng/ml in obese men and 3.1 ng/ml in morbidly obese men. CONCLUSION Across the study population, increased BMI was significantly inversely associated with lower PSA. Based on a theoretical model in which increased plasma volume in the obese dilutes PSA levels we propose new cut-points for a positive screening test. Prostate 68: 373,380, 2008. © 2008 Wiley-Liss, Inc. [source] Plasma Exchange Before Surgery for Left Ventricular Assist Device ImplantationARTIFICIAL ORGANS, Issue 6 2008Rajko Radovancevic Abstract:, Left ventricular assist device (LVAD) implantation in end-stage heart failure patients is frequently associated with hemorrhagic complications requiring reoperation. The preoperative coagulopathic profile includes prolonged prothrombin time (PT), partial thromboplastin time (PTT), and bleeding time; platelet dysfunction; decreased coagulation factor activity; and increased inflammatory markers. We compare outcomes in LVAD patients treated with preoperative plasma exchange with concurrent, nonrandomized control patients. We reviewed data from 68 consecutive elective patients who received LVADs at our institution. Thirty-five received LVADs after preoperative plasma exchange (replacement of one plasma volume of fresh frozen plasma), and 33 received LVADs without plasma exchange. Groups were comparable in age, sex, body weight, New York Heart Association class, intra-aortic balloon pump insertion, cardiac index, pulmonary capillary wedge pressure, creatinine, total bilirubin, hemoglobin levels, PT, international normalized ratio, PTT, and platelet count. Early mortality was lower in the plasma exchange group (0% [0/35] vs. 18% [6/33], P = 0.026), and postoperative chest tube drainage decreased by 33% (P = not significant). Blood transfusion requirements were similar.Perioperative mortality decreased in patients treated with plasma exchange before LVAD implantation. [source] Fluid Volumes Determination by Impedance Spectroscopy and Hematocrit Monitoring: Application to Pediatric HemodialysisARTIFICIAL ORGANS, Issue 2 2001Marianne Fenech Abstract: A method for extracting fluid volumes from multifrequency bioimpedance, which takes into account the body geometry and the presence of nonconducting elements, was tested on 12 young dialyzed patients against correlations for total body water volumes (TBW) from Watson et al. and Humes et al. Our calculations of TBW from impedance were found to overestimate Humes' values by 0.25 L (0.8%) postdialysis and by 2.08 L (6.5%) predialysis. Extracellular water (ECW) was found to contribute an average of 93% of ultrafiltered volume. Intracellular water volume (ICW) determination from impedance was found to be too imprecise to predict its variation during dialysis; therefore, ICW variations were calculated as the difference between ultrafiltration and ECW changes. The continuous recording of hematocrit by an optical device monitored changes in plasma and interstitial volumes. In most cases, ultrafiltration was compensated mainly by a contribution from interstitial fluid, and the drop in plasma volume was generally moderate. [source] | |||||||||||||||||||||||||||||||