An intravascular protein osmometer

1983 ◽  
Vol 244 (5) ◽  
pp. H726-H729
Author(s):  
J. W. Henson ◽  
R. A. Brace
Keyword(s):  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Hollow Fiber ◽  
Continuous Measurement ◽  
Colloid Osmotic Pressure ◽  
Artificial Kidney ◽  
Albumin Concentration ◽  
Simple Method ◽  
On Line ◽  
Polyethylene Tubing

Our purpose was to develop an intravascular osmometer for measuring the colloid (i.e., protein) osmotic pressure (COP) of circulating blood. A semipermeable hollow fiber from a Cordis Dow artificial kidney (C-DAK 4000) was attached to polyethylene tubing on one end, filled with saline, and sealed at the other end. This was small enough to be inserted into the vasculature of research animals. Protein osmotic pressure plus hydrostatic pressure was measured by a Statham pressure transducer attached to the hollow fiber. Simultaneously, a second catheter and transducer was used to measure hydrostatic pressure, which was subtracted from the pressure measured from the fiber with an on-line computer. The system was documented by a variety of tests. The colloid osmotic pressure vs. albumin concentration curve determined with the fiber is identical to the curve determined by standard membrane osmometry. The time constant for 2- and 8-cm fibers was 2.6 +/- 0.6 and 1.5 +/- 0.5 (+/- SD) min, respectively. The reflection coefficient (+/- SD) of the fiber for NaCl is 0.042 +/- 0.019 (n = 38); COP measured at varying temperatures (absolute scale) changed linearly as expected from COP = nCRT (i.e., van't Hoff's law). Finally, hollow-fiber osmometers were inserted into femoral veins of dogs and sheep, and blood COP was continuously recorded during osmotic manipulations. In conclusion, we attempted to develop and document a simple method for continuous measurement of intravascular colloid osmotic pressure.

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

1997 ◽  
Vol 83 (2) ◽  
pp. 407-413 ◽  
Author(s):  
Andrew Haskell ◽  
Ethan R. Nadel ◽  
Nina S. Stachenfeld ◽  
Kei Nagashima ◽  
Gary W. Mack
Keyword(s):  
Osmotic Pressure ◽  
Colloid Osmotic Pressure ◽  
Cycle Ergometer ◽  
Escape Rate ◽  
Albumin Concentration ◽  
Vascular Space ◽  
Transcapillary Escape Rate ◽  
Ergometer Exercise ◽  
Leg Muscle ◽  
Exercise Induced

Haskell, Andrew, Ethan R. Nadel, Nina S. Stachenfeld, Kei Nagashima, and Gary W. Mack. Transcapillary escape rate of albumin in humans during exercise-induced hypervolemia. J. Appl. Physiol. 83(2): 407–413, 1997.—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 μl ⋅ 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.

Influence of hydrostatic pressure gradients on regulation of plasma volume after exercise

1998 ◽  
Vol 85 (2) ◽  
pp. 667-675 ◽  
Author(s):  
Gary W. Mack ◽  
Roger Yang ◽  
Alan R. Hargens ◽  
Kei Nagashima ◽  
Andrew Haskell
Keyword(s):  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Plasma Volume ◽  
Fluid Pressure ◽  
Colloid Osmotic Pressure ◽  
Upright Position ◽  
Upright Posture ◽  
Immediate Recovery ◽  
Before And After ◽  
The Impact

The impact of posture on the immediate recovery of intravascular fluid and protein after intense exercise was determined in 14 volunteers. Forces which govern fluid and protein movement in muscle interstitial fluid pressure (PISF), interstitial colloid osmotic pressure (COPi), and plasma colloid osmotic pressure (COPp) were measured before and after exercise in the supine or upright position. During exercise, plasma volume (PV) decreased by 5.7 ± 0.7 and 7.0 ± 0.5 ml/kg body weight in the supine and upright posture, respectively. During recovery, PV returned to its baseline value within 30 min regardless of posture. PV fell below this level by 60 and 120 min in the supine and upright posture, respectively ( P < 0.05). Maintenance of PV in the upright position was associated with a decrease in systolic blood pressure, an increase in COPp (from 25 ± 1 to 27 ± 1 mmHg; P < 0.05), and an increase in PISF (from 5 ± 1 to 6 ± 2 mmHg), whereas COPi was unchanged. Increased PISFindicates that the hydrostatic pressure gradient favors fluid movement into the vascular space. However, retention of the recaptured fluid in the plasma is promoted only in the upright posture because of increased COPp.

Functional characteristics of the renal interstitium

1981 ◽  
Vol 241 (2) ◽  
pp. F105-F111 ◽  
Author(s):  
M. Wolgast ◽  
M. Larson ◽  
K. Nygren
Keyword(s):  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Plasma Proteins ◽  
Protein Transport ◽  
Fluid Transport ◽  
Colloid Osmotic Pressure ◽  
Capillary Membrane ◽  
Tubular Transport ◽  
Physical Forces ◽  
Capillary Fluid

The renal interstitial space analyzed as "inulin space" comprises about 13% in the rat. The Starling forces of this compartment are governed by the balance between tubular and capillary fluid transport and also by the leakage of plasma proteins from the blood side. Protein transport will occur in a large-pore system in the peritubular capillary membrane. During control antidiuresis, the interstitial hydrostatic pressure is 2-4 mmHg. The colloid osmotic pressure shows a larger variability but is generally about 5 mmHg. During conditions of depressed capillary reabsorption but unchanged tubular reabsorption, as in saline expansion, the interstitial hydrostatic pressure rises 3-4 times, whereas the colloid osmotic pressure will show a steep fall resulting from the increased fluid entry and unchanged protein transport. The interstitial volume increases only slightly, since it is compressed by the expanding tubules. The influence of interstitial physical forces on tubular transport remains unclear, mainly due to the inaccessibility of the lateral interspaces to direct measurement of relevant parameters.

scholarly journals The Mechanism of Urine Formation in Invertebrates

1936 ◽  
Vol 13 (3) ◽  
pp. 309-328
Author(s):  
L. E. R. PICKEN
Keyword(s):  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Body Fluid ◽  
External Medium ◽  
Carcinus Maenas ◽  
Colloid Osmotic Pressure ◽  
Body Fluids ◽  
The Body ◽  
Small Animals ◽  
Urine Formation

1. In Carcinus maenas: (a) The blood may be hypertonic, isotonic or hypotonic to the external medium. (b) The urine may be hypertonic, isotonic or hypotonic to the blood, and its concentration may differ in the two antennary glands. (c) The hydrostatic pressure of the body fluid is c. 13 cm. of water. (d) The colloid osmotic pressure of the blood is c. 11 cm. of water. (e) The urine probably contains protein and has a colloid osmotic pressure of c. 3 cm. of water. 2. In Potamobius fluviatilis: (a) The blood is hypertonic to the external medium. (b) The urine is hypotonic to the blood but hypertonic to the external medium and its concentration may differ in the two antennary glands. (c) The hydrostatic pressure of the body fluid is c. 20 cm. of water. (d) The colloid osmotic pressure of the blood is c. 15 cm. of water. (e) The urine may contain protein and has a colloid osmotic pressure (calculated) of c. 2 cm. of water. 3. In Peripatopsis spp.: (a) The blood is hypertonic to the urine. (b) The hydrostatic pressure of the body fluid is c. 10 cm. of water. (c) The colloid osmotic pressure (calculated) of the blood is c. 5 cm. of water. (d) The urine may contain protein and has a colloid osmotic pressure (calculated) of c. 2.5 cm. of water. 4. It is concluded that filtration is possible and that secretion and resorption almost certainly occur in the formation of the urine. 5. A microthermopile is described. 6. Methods are described for measuring the hydrostatic pressure and the colloid osmotic pressures of the body fluids in small animals.

P1090DETERMINATION OF ABSOLUTE BLOOD VOLUME USING ONLINE DIALYSATE DILUTION: WHEN SHOULD BE MEASURED?

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Susanne Kron ◽  
Daniel Schneditz ◽  
Til Leimbach ◽  
Joachim Kron
Keyword(s):  
Blood Volume ◽  
Venous Blood ◽  
Dry Weight ◽  
Time Frame ◽  
Colloid Osmotic Pressure ◽  
Study Patient ◽  
Dialysis Session ◽  
Bolus Volume ◽  
Simple Method ◽  
On Line

Abstract Background and Aims Current on-line haemodiafiltration (HDF) machines equipped with a blood volume monitor (BVM) and an on-line bolus function have the potential for measuring absolute blood volume (aBV). Recently, we developed a simple method to determine absolute BV in everyday dialysis sessions. The aim of the present study was to evaluate the reproducibility of measurements. Method Intra-individual reproducibility was studied in 10 patients during a single dialysis session by 4 measurements of absolute BV: immediately after beginning before ultrafiltration (UF) was started, and after one, two and three hours. ABV was determined by indicator dilution. A defined volume bolus of 240 mL dialysate was infused into the venous blood line by pressing the emergency button of the HDF machine 5008 (FMC). For this reason, total UF volume was increased by 1L. UF was automatically stopped during and after the infusion. The resulting increase in relative blood volume (RBVpost-RBVpre) was measured by the ultrasonic relative BVM incorporated in the dialysis machine. ABV was measured in hourly intervals and for assessment of reproducibility the volume at treatment start (t=0) where RBV is 100% was calculated for all measurements as: aBV in mL = bolus volume 240 mL x 100% / increase RBV in % ABV data were normalized for body mass at dry weight (in mL/kg). Additionally, in 5 patients the RBV graph was monitored immediately at the beginning of dialysis without UF in a separate dialysis session. Results ABV at t=0 were consistently larger when calculated from measurements done immediately after the beginning compared to measurements obtained after 1 h (6.52 ± 1.40 L or 80.6 ± 14.5 mL/kg vs. 5.16 ± 1.40 L or 63.9 ± 14.3 mL/kg). Specific BV derived from 2 and 3 h measurements did not significantly differ from the measured volumes after 1 hour (61.4 ± 13.8 mL/kg, and 60.9 ± 13.9 mL/kg). The standard deviations of the 3 examinations in the same study patient during a further course of dialysis were between 0.6 and 5.3 ml/kg (ø 2.6 ml/kg). In a separate session, RBV decreases without UF at the beginning of dialysis in the first 3 minutes by 0.5 % and in 5 minutes by 0.6 %. Conclusion If BV is diluted by additional priming volume and bolus volume, a part of this volume will leave the circulation. This represented the time frame where the bolus was initially infused and the measurements were carried out. This loss is caused by the reduction in plasma colloid osmotic pressure induced by the dilution thereby changing the microvascular filtration equilibrium. The increase in RBV display is not solely caused by the bolus volume in this time and, and therefore, calculated BV would be overestimated by about 17 mL/kg. If measurement is performed at a later time, UF will take place and, consequently, refilling. This inward drive matches the outward bolus escape as a counterforce. BV measurement during a further course of dialysis is well reproducible with a deviation of only ± 2.6 ml/kg. The method would therefore be sufficiently precise in clinical practice. Therefore, we propose the determination of aBV only after 1 hour dialysis when a sufficient refilling takes place. With a software modification, the BV measurement could be routinely automated during each dialysis treatment. Manufacturers are asked to implement this technology in their devices.

The Mechanism of Urine Formation in Invertebrates

1937 ◽  
Vol 14 (1) ◽  
pp. 20-34 ◽  
Author(s):  
L. E. R. PICKEN
Keyword(s):  
Sodium Chloride ◽  
Hydrostatic Pressure ◽  
Osmotic Pressure ◽  
Vapour Pressure ◽  
Average Rate ◽  
Colloid Osmotic Pressure ◽  
Pericardial Fluid ◽  
Anodonta Cygnea ◽  
Cent Sodium ◽  
Urine Formation

1. In Anodonta cygnea: (a) The blood has a vapour pressure equivalent to that of a solution of ca. 0.10 per cent sodium chloride. (b) The pericardial fluid is isotonic with the blood. (c) The urine has a vapour pressure equivalent to that of a solution of ca. 0.06 per cent sodium chloride. (d) The hydrostatic pressure of the blood is ca. 6 cm. of water. (e) The calculated colloid osmotic pressure is ca. 3.8 mm. of water. (f) The average rate of filtration of fluid into the pericardium is ca. 250 c.c. in 24 hours. (g) The salt uptake from ingested phytoplankton is estimated as equivalent to 0.012. g. sodium chloride in 24 hours. (h) The loss of osmotically active substance in the urine is estimated as equivalent to 0.15 g. sodium chloride in 24 hours. 2. In Limnaea peregra the vapour pressure of the blood is equivalent to that of a solution of ca. 0.43 per cent sodium chloride. The pericardial fluid is isotonic with the blood, and the urine has a concentration equivalent to ca. 0.30 per cent sodium chloride. 3. In Limnaea stagnalis the hydrostatic pressure of the blood is ca. 8 cm. of water. The colloid osmotic pressure of the blood is ca. 2.5 cm. of water (calculated); that of the pericardial fluid is ca. 0.7 cm. of water.

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