Plasma Colloid Osmotic Pressure Research Articles

Plasma colloid osmotic pressure after blood volume repletion with Oxyglobin, hetastarch, or whole blood in pregnant sheep

In preliminary measurements, Oxyglobin and hetastarch had colloidal osmotic pressures of 35 and 31 mm Hg, respectively, while ovine plasma (n = 17) had an osmotic pressure of 20 (16, 24) mm Hg, median (minimum, maximum). We hypothesized that Oxyglobin administration after hemorrhage would increase maternal plasma colloidal osmotic pressure (COP) more than hetastarch and that both would draw water from the fetus across an osmotic gradient.

Is compartment pressure related to plasma colloid osmotic pressure, in patients during and after cardiac surgery?

Haemodilution is always considerable during cardiopulmonary bypass (CPB). If this extra fluid sits in the muscle compartments then a corresponding rise in the compartment pressure (CP) is to be expected. The aim of this study was to measure pressure changes in a body compartment with new equipment, the MTC (Microtransducer). Changes in plasma colloid osmotic pressure (COP) were also measured during and after CPB to find a connection, if any, between CP and plasma COP. Ten elective consecutive CPB patients were studied. A 3-French (3-F) catheter-size electronic MTC was inserted in an anterior tibial compartment before CPB. The CP was monitored for 48 h. Plasma COP was also measured before, during and after CPB. CP increased significantly during and after CPB in all patients (p=0.01). COP decreased significantly in all patients (p=0.005), but no correlation was found between changes in COP and CP values in this study. Most of the patients reached their highest CP just after weaning off bypass. The CP remained elevated for 48 h, even though it then tended to decrease again. None of the patients reached the starting value within 48 h. COP decreased rapidly after going on bypass, but returned towards its starting value approximately 6 h after bypass. It is concluded that CP increases considerably during and after CPB and stays increased for at least 2 days after CPB. COP decreases during CPB, but reaches normal values 6 h after the CPB. No correlation was found between changes in CP and COP The MTC is a safe and easy way to measure intracompartment pressure.

Resuscitation of severe thermal injury with hypertonic saline dextran: effects on peripheral and visceral edema in sheep.

Edema of tissue not directly injured by heat is a common complication after resuscitation of burn shock. Hypertonic 7.5% NaCl 6% dextran (HSD) infusion reduces early fluid requirements in burn shock, but the effects of HSD on peripheral and visceral tissue edema are not well-defined. We measured the microcirculatory absorptive pressures of burned and nonburned skin and tissue water content of skin and other tissues in anesthetized sheep after 70% to 85% total body surface area scald and resuscitation. Fluid infusion was initiated 30 minutes after injury using 10 mL/kg HSD (n = 11) or lactated Ringer's (LR) (n = 12), with infusion rates titrated to restore and maintain preburn oxygen delivery (DO2). Thereafter, both groups received LR infusions as needed to maintain DO2 until the study's end at 8 hours. Colloid osmotic pressure was measured in plasma, and combined interstitial colloid osmotic and hydrostatic pressures were measured in skin. Both treatments successfully restored DO2, but fluid requirements were less with the HSD group than with the LR group (43+/-19 mL/kg vs. 194+/-38 mL/kg, respectively, p < 0.05). The peripheral and visceral tissue water contents at 8 hours postinjury until the end of the study in both burn groups were significantly higher than in nonburn controls. However, HSD-treated sheep had significantly less water content in the colon (less 28%), liver (less 9%), pancreas (less 55%), skeletal muscle (less 21%), and nonburned skin (less 12%) compared with LR-treated sheep (p < 0.05 for each). HSD-treated sheep maintained significantly higher (3 to 5 mm Hg) plasma colloid osmotic pressure than LR-treated sheep. There were no observed differences in edema in burn skin between the two treatment groups. The early volume-sparing effect of HSD and reduction in tissue edema are likely attributed to an increased extracellular osmolarity and a better maintenance of the plasma oncotic pressure.

Measurement of Plasma Colloid Osmotic Pressure in Normal Thoroughbred Neonatal Foals

A normal plasma colloid osmotic pressure (COP) interval was established for foals and compared to values for adult horses. Plasma samples were obtained from 38 Thoroughbred foals that had normal findings on postfoaling examination and 10 healthy Thoroughbred adult horses. Samples were analyzed using a commercially available colloid osmometer. Fifty samples were obtained from 38 foals. Twelve foals had 2 samples taken, 1 during the 1st 24 hours of life and the 2nd between 24 and 72 hours of life. For foals with 2 samples, only 1 randomly selected value was used in group analysis. Total plasma protein, albumin, and globulin concentrations were measured on all samples from foals. The mean measured plasma COP for foals was 18.8 ± 1.9 mm Hg for the 38 samples analyzed. Measured plasma COP did not differ significantly over the time period examined for either the 12 paired samples (P= .13) or with regression analysis of the 38 samples (P= .13). Calculation of mean COP, based on previously published quadratic equations using total protein, albumin, and globulin concentrations, underestimated mean measured foal COP values except for when total protein measured by refractometer was used in the Landis‐Pappenheimer equation. In conclusion, the plasma COP interval (95% CI: 15.0 mm Hg, 22.6 mm Hg) obtained for healthy foals in this study was found to be lower than that of healthy adult Thoroughbreds (20.6 ± 0.7 mm Hg, P= .006).

Transcapillary Forces and the Development of Oedema in the Lower Limb of Patients with Chronic Critical Limb Ischaemia (CLI)

Objective factors regulating transcapillary fluid transport were investigated to elucidate the causes of oedema in CLI. Material sixteen patients, 6 men and 10 women (mean age of 79±10.3 years) with unilateral CLI and peripheral pitting oedema. Methods measurements were performed in both limbs. Interstitial fluid was collected by applying blister suction cups on the dorsolateral part of the foot and colloid osmotic pressure of this fluid (COP if) was measured in a colloid oncometer. Plasma colloid osmotic pressure (COP pl) was obtained from venous blood. Interstitial fluid pressure (P if) was measured by wick-in-needle technique. Results mean COP if in the limbs with CLI was 2.3 S.D. 0.5 mmHg, significantly lower than in the limbs without CLI (3.1 S.D. 0.7 mmHg, p<0.0001). Mean COPpl was 21.1 S.D. 1.8 mmHg, which was lower than in healthy controls. Mean plasma albumin concentration was 30 S.D. 6 g/l which was lower than the reference values. Mean P if in the limbs with CLI was 0.7 S.D. 1.6 mmHg, significantly higher than in the limbs without CLI (−1.4 S.D. 1.4 mmHg, p<0.0001). The calculated mean reabsorption pressure (Pr ) in the limbs with CLI was 19.6 S.D. 1.7 mmHg, significantly higher than in the contralateral limbs (16.7 S.D. 2.1 mmHg,p <0.001). Conclusion a low plasma albumin concentration in patients with CLI agrees with the reduction in COPpl but cannot explain the oedema formation, since it is unilateral. The high P r may cause a high transcapillary filtration pressure, resulting in a relatively great net filtration and subsequent oedema formation.

Coordinate augmentation in expression of genes encoding transcription factors and liver secretory proteins in hypo-oncotic states

In the nephrotic syndrome (NS) proteins of intermediate size (40 to 200 kD) are lost into the urine resulting in a decrease in plasma albumin concentration and as a consequence a reduction in plasma colloid osmotic pressure (pi). Plasma pi has also been reported to be reduced in the condition of hereditary analbuminemia. The liver, in an apparent compensatory response, increases synthesis of a group of secreted proteins defending plasma pi. Regulation of several of these proteins, including both positive and negative acute phase proteins, is at the transcriptional level. This is the only known condition in which transcription of both positive and negative acute phase proteins (APPs) are increased simultaneously. The specific transcription factor(s) that might regulate this cascade is not defined. RNA was extracted from livers of 5 rats with hereditary analbuminemia (the Nagase analbuminemic rat, NAR), 5 rats with NS induced by adriamycin (Adria), 5 rats with NS caused by passive Heymann nephritis (NS) and 5 control animals. The concentrations of mRNAs encoding four secreted proteins (albumin, transferrin, fibrinogen, and apo A-1), five transcription factors, early growth response factor 1 (EGRF-1), HNF-4, NGFI-C, EGR-3, and Krox20 relative to two housekeeping genes, beta actin and GAPDH were determined simultaneously using kinetic reverse transcriptase polymerase chain methodology (kRT-PCR). The levels of all mRNAs encoding secreted proteins except for albumin (which was reduced in NAR) were increased in NS and NAR and correlated significantly with one another. mRNA encoding EGRF 1 was increased fivefold in NS and NAR, and correlated significantly with mRNAs encoding Apo A-1, transferrin and albumin in the two NS groups. HNF-4 mRNA was increased approximately twofold in both NS groups and correlated with albumin (R = 0.881, P < 0.001), transferrin (R = 0.563, P = 0.012) and apo A-1 (R = 0.644, P = 0. 003). While fibrinogen mRNA correlated with that of each of the other secreted proteins, it did not correlate with either HNF-4 or EGRF-1 mRNA. Krox20, EGR3 and NGF1C were expressed at nearly undetectable levels. The hepatic response in conditions characterized by reduced plasma pi include increased levels of mRNAs encoding a group of secreted proteins, including the negative APPs albumin, transferrin and apo A-1, and the positive APP fibrinogen. Levels of mRNAs encoding negative APPs and fibrinogen correlate with one another, suggesting that they are coordinately controlled. Both EGRF-1 and HNF-4 may regulate the expression of the negative APPs, which have increased transcription in hypo-oncotic states.

Regulation of Intraocular Pressure after Water Drinking

Acute oral water loading transiently elevates intraocular pressure (IOP) via mechanisms that remain unexplained. We tested the possibilities that water drinking might elevate IOP by creating a blood-aqueous osmotic gradient, or that it might instead alter active ion pumping and the formation of aqueous humor. In the first series, 16 young, healthy individuals were studied during dehydration and for 1 hour after rehydration (14 mL H2O/kg body weight). Hematocrit, total plasma osmolality, and plasma colloid osmotic pressure were determined simultaneously with measurements of IOP. In a second series (N = 16), rehydration occurred after pretreatment with either placebo or a topical carbonic anhydrase inhibitor (1 drop 2% dorzolamide in each eye, 12 and 2 hours before oral water loading). In both series, mean IOP increased significantly 15 minutes after water ingestion and remained elevated above baseline for 45 minutes. In contrast, colloid osmotic pressure and hematocrit were unaltered by water drinking, and neither these variables nor total plasma osmolality correlated with IOP. In the second series, pretreatment with dorzolamide reduced baseline IOP, but failed to alter the magnitude or time course of IOP elevations induced by water drinking. Because water drinking failed to create a blood-ocular osmotic pressure gradient, neither vitreous hydration nor increased aqueous ultrafiltration can explain increases in IOP after acute hydration. Because the increase in ocular tension apparently also is independent of active bicarbonate pumping, factors affecting aqueous drainage must explain the water drinking effect.

Pathophysiology of Edema Formation in Children with Nephrotic Syndrome Not Due to Minimal Change Disease

It has been shown that children with nephrotic syndrome due to minimal change disease (MCD) can present with avid salt retention and stimulated vasoactive hormones, as well as with stable edema. The present study examines these conditions in children with nephrotic syndrome not due to MCD (non-MCD). In six children with hypovolemic symptoms (congenital nephrotic syndrome in four), strong sodium retention (fractional sodium excretion, FE(Na), 0.2 +/- 0.2%) was found. Lithium clearance (FE(Li)) and maximal water excretion (Vmax) were suppressed, suggesting avid sodium reabsorption throughout the nephron. Aldosterone, renin, and norepinephrine were elevated. Sixteen other children with non-MCD had stable edema. FE(Na) was 1.8 +/- 1.1%, whereas FE(Li), Vmax, and hormones were normal, and not different from data in 35 nonproteinuric children. In children with MCD, 12 presented with hypovolemic symptoms and strong sodium retention (FE(Na) 0.3 +/- 0.3%), whereas 15 were stable (FE(Na) 1.1 +/- 0.7%). Regarding tubular sodium handling and hormones, the same distinction could be made as for the children with non-MCD. However, hypoproteinemia differed. In the children with non-MCD lesions, plasma colloid osmotic pressure was significantly lower in the hypovolemic types (4.2 +/- 0.4 mmHg) than in those with stable edema (13.0 +/- 3.8 mmHg; P < 0.05); in MCD, no such difference existed (respectively, 8.1 +/- 3.0 and 9.9 +/- 2.2 mmHg). In summary, children with nephrotic syndrome may present with pathophysiologic pictures of decreased effective circulating volume or of stable edema, regardless of whether they have non-MCD or MCD. The pathogenesis of the hypovolemic picture seems to be different, since it is associated with extreme hypoproteinemia only in the children with non-MCD.

Capillary protein leak syndrome appears to explain fluid retention in cancer patients who receive docetaxel treatment.

The aim of our study was to elucidate whether the fluid retention syndrome induced by docetaxel is caused by capillary protein leakage or by other mechanisms. Twenty-four patients with advanced or metastatic non-small-cell lung cancer (NSCLC; 23 patients) or metastatic head and neck cancer (one patient) were included on this prospective, nonrandomized trial. Docetaxel 100 mg/m2 was administered every 3 weeks with 5 days of dexamethasone prophylaxis to avoid hypersensitivity reactions and edema formation. Transcapillary forces, ie, colloid osmotic pressure of plasma (COPpl) and interstitial fluid (COPint) and interstitial hydrostatic pressure (Pint), were measured before the start of treatment and after total docetaxel doses of 200 and 500 mg/m2 by means of the well-documented wick and wick-in-needle methods. Body weight, degree of edema, blood pressure, and heart rate and hemoglobin, hematocrit, albumin, and total protein values were registered in parallel. After a total docetaxel dose of 200 mg/m2, COPpl, COPint, and hemoglobin, hematocrit, albumin, and total protein values had decreased significantly; Pint and body weight were unchanged; and only mild edema was observed. These findings suggest a plasma volume increase followed by enhanced fluid filtration to the interstitium. After a cumulative docetaxel dose of 500 mg/m2, the COPpl continued to decrease significantly, but COPint remained unchanged despite a significant increase in mean body weight and edema formation. These observations support the theory of a capillary protein leakage. Docetaxel appears to induce an initial enhancement of fluid filtration followed by a capillary protein leakage that leads to edema formation.

Hemodynamics of gastric microcirculation in rats.

Recently, we described a novel preparation of rat stomach for vascular micropuncture studies. The aim of the present study was to directly measure basic microvascular parameters along the length of the gastric vasculature. Blood vessels were identified, and intravascular pressure was measured with a servo-null transducer, vessel dimensions with videometry, blood flow with microspheres, and plasma colloid osmotic pressure with an osmometer. When systemic arterial pressure was 100-110 mmHg, intravascular pressures in small arteries, primary, secondary, and tertiary submucosal arterioles, mucosal terminal arterioles, and muscle arterioles were 77.8 +/- 2.6, 74.6 +/- 2.5, 54.1 +/- 1.8, 34.4 +/- 1.6, 32.4 +/- 1.2, and 30.5 +/- 1.4 (SE) mmHg, respectively. Intravascular pressures in collecting veins, secondary and primary submucosal venules, muscle venules, and small veins were 26.6 +/- 1.1, 21.8 +/- 1.6, 17.1 +/- 0. 8, 18.2 +/- 0.9, and 14.4 +/- 0.6 mmHg, respectively. Capillary pressure in the mucosa (28 mmHg), as estimated by interpolation between terminal arteriole and collecting venule pressures, was significantly higher than in the muscle layer (23.6 +/- 1.4 mmHg). A total of 155 vessels from 25 animals were sampled. Relative blood flows were 16 +/- 3% in the muscle and 84 +/- 3% in the mucosa-submucosa. Analysis of filtration forces in these two different capillary beds suggests that gastric mucosal capillaries are primarily a filtering network, whereas muscle capillaries are in fluid balance. Calculated resistance ratios indicate low precapillary but relatively high postcapillary vascular resistance in the gastric mucosa.

Preventing hemodilution abolishes natriuresis of water immersion in humans.

The hypothesis was tested that hemodilution is one of the determinants of the water immersion (WI)-induced natriuresis. Eight males were subjected to 3 h of 1) WI to the midchest (Chest), 2) WI to the neck combined with thigh cuff-induced (80 mmHg) venous stasis (Neck + stasis), and 3) a seated time control (n = 6). Central venous pressure and left atrial diameter increased to the same extent during Chest and Neck + stasis (P < 0.05), whereas renal sodium excretion only increased during Chest from 77 +/- 7 to 225 +/- 13 micromol/min (P < 0.05). During Chest, plasma colloid osmotic pressure (COP) decreased from 27.7 +/- 0.7 to 25.1 +/- 0.7 mmHg (P < 0.05), and plasma volume (PV) increased from 3,263 +/- 129 to 3,581 +/- 159 ml (P < 0.05), whereas these variables remained unchanged during Neck + stasis. Plasma norepinephrine concentration decreased similarly during Chest and Neck + stasis by 45 +/- 7 and 34 +/- 4%, respectively (P < 0.05), whereas plasma renin activity decreased only during Chest (P < 0.05). In conclusion, during WI in humans 1) hemodilution (decrease in COP and increase in PV) is a pivotal stimulus for the natriuresis and 2) central blood volume expansion without hemodilution does not augment renal sodium output.

Effect of plasma colloid osmotic pressure on intraocular pressure during haemodialysis

BACKGROUNDIn a previous case report, it was shown that an increase in plasma colloid osmotic pressure induced by the removal of fluid during haemodialysis was instrumental in decreasing intraocular pressure....

Chronic lymph flow responses to hyperproteinemia

The long-term responses of lymph flow, lymph protein transport, and the permeability-surface area (PS) product to hyperproteinemia have been studied in conscious dogs. Plasma protein concentration (PPC) was increased by daily intravenous infusion of previously collected autologous plasma for 9 days. Lymph flow was determined by collecting lymph chronically from a lymphatic afferent to the popliteal node in the hind leg. Compared with the average value during the normal-PPC period, the following changes occurred during 10 days of high PPC: lymph flow decreased from 12.3 +/- 1.1 to 3.8 +/- 0.6 microl/min, lymph protein transport decreased from 241 +/- 24 to 141 +/- 21 microg/min, PS product decreased from 4.7 +/- 0.5 to 3.0 +/- 0.5 microl/min, PPC increased from 7.1 +/- 0.1 to 8.8 +/- 0.4 g/dl, lymph protein concentration increased from 1.9 +/- 0.1 to 3.8 +/- 0.1 g/dl, plasma colloid osmotic pressure increased from 18. 6 +/- 0.8 to 24.2 +/- 2.1 mmHg, and lymph colloid osmotic pressure increased from 4.8 +/- 0.2 to 10.4 +/- 0.7 mmHg. In conclusion, long-term hyperproteinemia in dogs resulted in chronic decreases in lymph flow, lymph protein transport, and the PS product and chronic increases in lymph protein concentration and lymph colloid osmotic pressure. The marked decrease in lymph flow during hyperproteinemia decreased lymph protein transport and thus contributed to the increase in lymph protein concentration. In addition, the decreases in PS product and lymph protein transport suggest that transcapillary protein flux decreases during hyperproteinemia.

Identification of operational clues to dry weight prescription in hemodialysis using bioimpedance vector analysis

Identification of operational clues to dry weight prescription in hemodialysis using bioimpedance vector analysis

The balance hypothesis of renin release

There is much research on renin release, but there are still some controversies according to the literature (1). The factors that increase renin release include: (a) low sodium diet; however, it was also reported that a high sodium diet may also increase renin release (2); (b) stimulation of sympathetic nerves either electrically or by adrenaline, but it was also reported that renin release remains the same after renal denervation (1); (c) decrease in sodium ion concentration in the macula densa portion of the distal tubule (MDPT). But there was an opposite viewpoint (3,4); (d) decrease in blood pressure, water deprivation (5), increase in plasma colloid osmotic pressure, ligation of the ureter, electrical stimulation of the brain and a decrease in sodium concentration in the cerebrospinal fluid. The factors which decrease renin release are injection of A2 (angiotensin 2), A3 (angiotensin 3) and some anaesthetics. Perhaps the balance hypothesis of renin release adjustment can answer some of the above controversies. The negative feedback mechanism is the reason why the renal tubule returns to the cortex from the medulla and forms the juxtaglomerular apparature with the hypertrophic wall of its own (macula densa) and that of the afferent arteriole (AA). The renin is stored between the MDPT and the AA. The situation provides a balance, with MDPT and AA being the two sides of the balance. The juxtaglomerular apparatus (JGA) is like the fulcrum of the balance, and its state indicates the amount of renin release (see Fig. 1). The amount of renin release perhaps varies in response to RNC (RNC is the ratio of Na ÷ in AA to to Na ÷ in MDPT), RSF (RSF is the I I a' on oq a*io I I Na+ concentration I Speed of fluid flow

Transcapillary escape rate of albumin in humans during exercise-induced hypervolemia.

To test the hypotheses that plasma volume (PV) expansion 24 h after intense exercise is associated with reduced transcapillary escape rate of albumin (TERalb) and that local changes in transcapillary forces in the previously active tissues favor retention of protein in the vascular space, we measured PV, TERalb, plasma colloid osmotic pressure (COPp), interstitial fluid hydrostatic pressure (Pi), and colloid osmotic pressure in leg muscle and skin and capillary filtration coefficient (CFC) in the arm and leg in seven men and women before and 24 h after intense upright cycle ergometer exercise. Exercise expanded PV by 6.4% at 24 h (43.9 +/- 0.8 to 46.8 +/- 1.2 ml/kg, P < 0.05) and decreased total protein concentration (6.5 +/- 0.1 to 6.3 +/- 0.1 g/dl, P < 0.05) and COPp (26.1 +/- 0.8 to 24.3 +/- 0.9 mmHg, P < 0.05), although plasma albumin concentration was unchanged. TERalb tended to decline (8.4 +/- 0.5 to 6.5 +/- 0.7%/h, P = 0.11) and was correlated with the increase in PV (r = -0.69, P < 0.05). CFC increased in the leg (3.2 +/- 0.2 to 4.3 +/- 0.5 microl . 100 g-1 . min-1 . mmHg-1, P < 0. 05), and Pi showed a trend to increase in the leg muscle (2.8 +/- 0. 7 to 3.8 +/- 0.3 mmHg, P = 0.08). These data demonstrate that TERalb is associated with PV regulation and that local transcapillary forces in the leg muscle may favor retention of albumin in the vascular space after exercise.

Plasma protein abnormalities in nephrotic syndrome: effect on plasma colloid osmotic pressure and viscosity

The concentrations of 25 plasma proteins were measured in 22 patients with membranous nephropathy. For some large proteins, the plasma concentrations were increased; there were also large proteins with low plasma concentrations, but small or medium-sized proteins showed uniformly lower plasma concentration than the controls. Plasma colloid osmotic pressure (pi) and viscosity (eta) were not interrelated but showed positive and significant correlations with plasma concentrations of small and medium-sized proteins (pi) and plasma concentrations of large proteins (eta), respectively. Nephrotic plasma is not efficient in maintaining plasma pi but highly efficient in maintaining plasma eta. High plasma fibrinogen concentrations and low antithrombin III concentrations may predispose to thrombosis, and low IgG concentrations may account for the higher predisposition to bacterial infection. The relative composition of nephrotic plasma is heavily dependent on the size of the different proteins. Plasma pi and eta are also maintained by the relative preponderance of different plasma proteins.

Marked decrease in intraocular pressure in a neovascular glaucoma patient during hemodialysis

While the relationship between intraocular pressure and plasma osmolarity has been investigated during hemodialysis, no research has been published concerning the relationship between intraocular pressure and plasma colloid osmotic pressure during hemodialysis. We describe a patient with neovascular glaucoma who demonstrated a marked decrease in intraocular pressure during hemodialysis. The patient's intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight were evaluated every 30 minutes during hemodialysis lasting 4.5 hours. Plasma osmolarity was almost constant during hemodialysis (beginning: 295 mOsm/L; ending: 305 mOsm/L), and plasma colloid osmotic pressure increased (beginning: 23.0 mm Hg; peak: 27.2 mm Hg). Weight loss was 5.7 kg. Intraocular pressure decreased markedly during hemodialysis (beginning: 53 mm Hg; ending: 14 mm Hg). This sharp decrease in intraocular pressure and the increase in plasma colloid osmotic pressure, indicate a relationship between plasma colloid osmotic pressure and the change in intraocular pressure during hemodialysis.

Hemodilution, central blood volume, and renal responses after an isotonic saline infusion in humans.

To test the hypothesis that hemodilution is a mediator of the renal responses to an isotonic saline infusion in the supine position, eight males underwent 1) intravenous infusion of 1.5 liter of saline over 21 min (Saline), 2) infusion of 1.5 liter of saline in combination with lower body negative pressure for 3 h (LBNP+Saline) to maintain central blood volume unchanged, and 3) a control study without infusion or LBNP. During the Saline series, central venous pressure (CVP) and left atrial diameter (LAD) increased by 4.4 +/- 0.6 mmHg and 2.6 +/- 0.4 mm (P < 0.05), respectively, whereafter they declined toward preinfusion levels. During LBNP+Saline, CVP and LAD were unchanged. Plasma colloid osmotic pressure remained unchanged during control and showed identical decreases by 5 mmHg (P < 0.05) in the Saline and LBNP+Saline series. During the 3rd h of LBNP, renal sodium excretion (U(Na)V) peaked at 296 +/- 55 micromol/min vs. a higher value of 383 +/- 54 micromol/min (P < 0.05) during Saline. The increase in U(Na)V above that of control during the 3rd h of LBNP+Saline constituted 48% of that during Saline. Plasma renin activity and plasma aldosterone concentration showed similar patterns of decrease after saline infusion irrespective of LBNP, whereas plasma norepinephrine was elevated late in the LBNP period compared with during Saline and control (P < 0.05). It is concluded that the maintenance of a constant CVP and LAD reduces the natriuresis of acute saline loading by about one-half. Thus hemodilution in conjunction with suppression of renin and aldosterone release (independent of change in CVP and LAD) might account for the remaining natriuresis of infusion.

Measurement of relative plasma volume and plasma refilling rate during ultrafiltration of hemodialysis by measuring apparatus of plasma colloidal osmotic pressure

The objective of this study is the prevention of unexpected hypotension during hemodialysis caused by unsuitable filtration rate. The plasma colloidal osmotic pressure (COP) was measured continuously during ultra-filtration, and relative plasma volume (%PV) and plasma refilling rate (PRR) were calculated during 12 ECUMs and one dialysis on twelve patients in early stage of chronic renal failure. Values of %PV and PRR calculated from COP were drawn in graphic curves, and analysed to obtain characteristic pattern. Minimum value of %PV (%PV min), maximum value of PRR (PRRmax) and time for PRR to decrease to 95% (95% PVt) on the curves were documented simultaneously. At the initial stage of %PV curve, obvious fall was observed on 6 of 13 estimation (initial fall of %PV). On the contrary at the initial stage of PRR curve, obvious rise was observed on 5 estimation (initial rise of PRR). A close relationship was indicated between the two phenomenons. In 6 cases with initial fall of %PV and in 5 cases with initial rise of PRR body weight, PRRmax and 95%PVt were lower than another cases without it. The ultra-infiltration velocity was estimated to be relatively high in these groups. In these 8 cases, filtrated water volume was judged as adequate clinically. In 4 of 5 cases without final fall of PRR, it was judged as inadequate and needed to evacuate more 0.9 to 3.0 kg (average of 1.8 +/- 1.07) of water from the patients. From the above, we concluded that our method is useful for deciding suitable velocity of ultrafiltration and dry weight in hemodialysis therapy.)