Plasma Equivalent Volume Research Articles

Phosphodiesterase 4 inhibition attenuates plasma volume loss and transvascular exchange in volume expanded mice

Phosphodiesterase 4 inhibition attenuates plasma volume loss and transvascular exchange in volume expanded mice

Artificial Liver Support System Using Large Buffer Volumes Removes Significant Glutamine and Is an Ideal Bridge to Liver Transplantation

Background Fulminant hepatitis is an intractable disease of varying etiology. Artificial liver support (ALS) is used to control serious symptoms of fulminant hepatitis, such as brain edema, which may induce postoperative neurological deficits. Patients and Methods ALS was evaluated in 12 patients with fulminant hepatitis who had been placed on an ALS system comprising plasma exchange and online hemodiafiltration. Six of 12 patients fell into an ahepatic state, the absolute indication for liver transplantation. The effects of ALS were evaluated on the basis of improvements in clinical symptoms, removal of glutamine (Gln), and brain computed tomography. Results All 12 patients regained consciousness with ALS and 5 survived; 7 died despite recovering from hepatic coma. The ALS systems sustained patients in an ahepatic state for more than 2 weeks. The median estimated plasma equivalent volume of removed Gln was 17.9 L (range, 6.7–64.3 L). There was a significant relationship between total buffer volume and the plasma equivalent volume of removed Gln. Conclusion Plasma exchange combined with hemodiafiltration using large buffer volumes is a promising and effective bridging method to liver transplantation.

Comparison of gadomer-17 and gadopentetate dimeglumine for differentiation of benign from malignant breast tumors with MR imaging

This study compared gadopentetate dimeglumine (molecular weight, 0.5 kD), a standard contrast medium, and Gadomer-17 (apparent molecular weight, approximately 35 kD), a new, clinically applicable, large-molecular contrast medium, with respect to their microvascular characterizations of experimentally induced breast tumors at magnetic resonance (MR) imaging. A spectrum of breast tumors, benign through highly malignant, was induced in Sprague-Dawley rats (n = 30) by intraperitoneal administration of N-ethyl-N-nitrosourea (ENU), a potent carcinogen. All animals underwent three-dimensional spoiled gradient-recalled MR imaging, with precontrast imaging and dynamic postcontrast imaging after injection of gadopentetate dimeglumine (0.1 mmol/kg) and Gadomer-17 (0.03 mmol/kg), administered in a random order at a 24-hour interval. Several microvascular parameters were compared: the endothelial transfer coefficient (K(PS)), a measure of microvascular permeability; the fractional plasma volume (fPV), and the plasma equivalent volume. Each MR imaging parameter was correlated with histopathologic findings. With Gadomer-17, the mean values for K(PS) and fPV were significantly greater in carcinomas than in fibroadenomas (P < .004 and .04, respectively). With gadopentetate dimeglumine, the mean values for fPV and PEV were significantly greater in carcinomas (P <. 004 and .02, respectively). Because of the high variability within both fibroadenoma and carcinoma groups, however, there were no significant correlations between K(PS), fPV, or PEV and histopathologic tumor grade as indicated by the Scarff-Bloom-Richardson score, for either agent. Although the K(PS) and fPV estimates obtained from dynamic MR imaging data with Gadomer-17 enhancement offer some potential for characterizing breast tumors, none of the quantitative microvascular parameters derived with either agent were significantly correlated with histopathologic tumor grade.

Interstitial albumin mass and transcapillary extravasation rate of albumin in DMBA-induced rat mammary tumours

Transcapillary extravasation rate for radio-iodinated human serum albumin (I-HSA) from plasma to interstitial fluid, interstitial albumin mass and interstitial albumin concentration have been determined in dimethyl-benz-alpha-anthracene (DMBA)-induced mammary tumours in rats. The plasma radioactivity of tracer was kept constant in awake, freely moving rats by a continuous infusion of I-HSA from 1 to 72 h after an initial priming dose. Capillary leakiness for I-HSA was calculated as the plasma equivalent volume of I-HSA located extravascularly after 1 h infusion divided by the blood volume in the tissue, i.e. as the fractional extravasation rate (FER). The experiments showed that FER was highest in tumours while intestine and skin had FER of about 70% and 25% that of tumour respectively. Heart and skeletal muscle had similar FER about 1/8 that of tumour. Interstitial albumin concentration in tumour averaged 42% of plasma albumin concentration in tumour. Intestine, heart and skeletal muscle had interstitial albumin concentrations between 34 and 37% of plasma albumin concentration while skin had an albumin concentration averaging 20% that of plasma. Lymph flow was calculated as the product of the fractional turnover rate constant for interstitial albumin and interstitial volume (extravascular 51Cr-EDTA volume) and averaged 36.7 X 10(-3) mg/g X h in tumour while intestine and heart had lymph flows of 19.1 X 10(-3) and 14.1 X 10(-3) ml/g X h respectively. In muscle and skin lymph flow was 2.4 X 10(-3) and 18.3 X 10(-3) ml/g X h respectively. It is suggested that the high interstitial fluid pressure previously observed in these tumours will contribute in maintaining interstitial volume in a steady state by opposing fluid filtration into the interstitium and maintaining a lymph flow high enough to remove excess fluid and protein from the interstitium.

A model of the kinetics of insulin in man.

The design of the present study of the kinetics of insulin in man combines experimental features which obviate two of the major problems in previous insulin studies. (a) The use of radioiodinated insulin as a tracer has been shown to be inappropriate since its metabolism differs markedly from that of the native hormone. Therefore porcine insulin was administered by procedures which raised insulin levels in arterial plasma into the upper physiologic range. Hypoglycemia was prevented by adjusting the rate of an intravenous infusion of glucose in order to control the blood glucose concentration (the glucose-clamp technique). (b) Estimation of a single biological half-time of insulin after pulse injection of the hormone has been shown to be inappropriate since plasma insulin disappearance curves are multiexponential. Therefore the SAAM 25 computer program was used in order to define the parameters of a three compartment insulin model. The combined insulin mass of the three compartments (expressed as plasma equivalent volume) is equal to inulin space (15.7% body wt). Compartment 1 is apparently the plasma space (4.5%). The other two compartments are extra-vascular; compartment 2 is small (1.7%) and equilibrates rapidly with plasma, and compartment 3 is large (9.5%) and equilibrates slowly with plasma. The SAAM 25 program can simulate the buildup and decay of insulin in compartments 2 and 3 which cannot be assayed directly. Insulin in compartment 3 was found to correlate remarkably with the time-course of the servo-controlled glucose infusion. Under conditions of a steady-state arterial glucose level, glucose infusion is a measure of glucose utilization. We conclude that compartment 3 insulin (rather than plasma insulin) is a more direct determinant of glucose utilization. We suggest that the combined use of glucose-clamp and kinetic-modeling techniques should aid in the delineation of pathophysiologic states affecting glucose and insulin metabolism.