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PubMed1991

The mechanisms and prevention of intravascular fluid loss after occlusion of the supraceliac aorta in dogs.

Mechanisms of intravascular fluid depletion after temporary occlusion of the supraceliac aorta were investigated in a canine model. During ischemia and reperfusion, hemodynamic parameters, superior mesenteric artery flow, intestinal mucosal perfusion, and mucosal permeability were monitored. After 12 hours of reperfusion, the volumes of intravenous electrolyte fluid required to maintain hemodynamic stability and fluid lost into the gastrointestinal tract and peritoneal cavity were measured. The distribution of total body water was analyzed by use of radionuclide dilution techniques. Group A animals underwent laparotomy only, group B had the supraceliac aorta occluded for 45 minutes, group C had superoxide dismutase administered after 45 minutes of aortic occlusion, and group D animals were exposed to mild hypothermia during a similar ischemia and reperfusion period. No significant difference was found in mean superior mesenteric artery flow or mucosal perfusion during ischemia among groups B, C, and D. During reperfusion superior mesenteric artery flow returned to values similar to control in all groups. Aortic occlusion increased mucosal permeability most significantly in group B (p less than 0.01). Mean intravenous fluid requirements (ml/mg) were the following: group A, 80 +/- 5; group B, 201 +/- 9 (p less than 0.01); group C, 116 +/- 7 (p less than 0.05); group D, 245 +/- 24 (p less than 0.05). Mean gastrointestinal fluid loss was highest in the hypothermic group and smallest if superoxide dismutase was given. Mean intracellular fluid volume was increased in groups B and D compared with group A (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMedDate not supplied

Extravascular lung water and peripheral volume status in hemodialysis patients with and without a history of heart failure.

Determining volume status in hemodialysis patients with a history of congestive heart failure (CHF) is difficult. Extravascular lung water (EVLW) may be derived from blood ultrasound velocity changes following injections of 0.9% and 5% saline. Bioimpedance spectroscopy can measure total body water (TBW) and its intracellular fluid (ICF) and extracellular fluid (ECF) compartments. We studied 29 clinically euvolemic hemodialysis patients, 12 of whom had a history of CHF. The ECF and ICF were measured before dialysis, and EVLW was measured during dialysis. Values of EVLW were similar between patients without CHF and those with CHF (3.55 ml/kg +/- 0.94 SD versus 3.88 ml/kg +/- 0.82 SD, respectively; p = NS). The ECF/ICF ratio was higher among patients with a history of CHF (1.27 +/- 0.29) than among those without such a history (1.04 +/- 0.04; p < 0.05), indicating that ECF volume overload was present in both groups, but was higher in those with a CHF history. There was a positive correlation between EVLW and ECF/ICF ratios (r = 0.54, p < 0.01). Measurements of EVLW were higher in two pulmonary edema patients ((7.95 ml/kg and 5.95 ml/kg; p < 0.05). The results of this study suggest that 1) hemodialysis patients with a history of CHF have more ECF volume overloaded than those without such a history; 2) the degree of ECF expansion is associated with increasing EVLW volume, even in patients without pulmonary edema; and 3) ECF volume expansion eventually exceeds limits and pulmonary edema occurs. These developing technologies of volume measurement may be of value in this challenging clinical area.

Aged↗
PubMed1983

Muscle intracellular electrolytes in patients with chronic uremia.

We performed 182 percutaneous muscle biopsies in 161 nondialyzed or dialyzed patients with chronic renal failure. Muscle sodium (NaM), potassium (KM), magnesium (MgM) and phosphorus (PM) were determined by neutron activation analysis and atomic absorption spectrophotometry. Intracellular water (H2OI) in muscle was increased in all groups of uremic patients but was not correlated with total muscle water (H2OM) which varied with the content of extracellular water (H2OE). In the nondialyzed patients KM, MgM, and PM were normal in relation to fat free solids (FFS). KM/MgM and KM/PM were also normal. Alkali soluble muscle protein (ASP) was low, and KM/ASP was significantly increased. In hemodialyzed patients and in predialysis peritoneal dialysis patients, KM/FFS and KM/MgM were high. For 22 to 24 hours after peritoneal dialysis, H2OM, H2OE, ClM, NaM, KM, and PM fell significantly, but H2OI was unchanged. The calculated intracellular potassium concentration (KI/H2OI) was significantly reduced in all groups of patients, even though KM was normal or increased. This decrease became more marked when calculating H2OE, H2OI, and KI/H2OI with the chloride method, assuming a reduced muscle transmembrane potential. There was a covariation between KM and PM, KM and H2OI, and KM and plasma potassium, but not between MgM and plasma magnesium or PM and plasma inorganic phosphate. Thus, typical features of chronically uremic muscle are an increase in intracellular water and normal or increased content of potassium in relation to various reference bases representing cell mass. However, the concentration of potassium in intracellular fluid is reduced, presumably because of inhibition of the sodium pump, which reduces transmembrane potential and interferes with the volume regulation of the muscle cells.

Adolescent↗
PubMed2001

Sodium replacement and fluid shifts during prolonged exercise in humans.

In the study presented here, we examined the affects of a close to complete replacement of sweat water and Na+ losses on fluid shifts during exercise. Six cyclists performed three 4-h rides at 55% of their peak oxygen uptake in a 20 degrees C environment while consuming 3.85 l of an 8% carbohydrate solution containing 5, 50 or 100 mEq.l-1 of Na+. Increases in Na+ intake reduced renal free water clearance from around 40 ml.h-1 to -8 and -121 ml.h-1 and led to a decrease in urine volume from approximately equal to 1.0 to 0.5 l (P < 0.05). In contrast, the 3.5-3.9 l fluid and 150-190 mEq Na+ losses in sweat were similar in each trial, as were the approximately equal to 80 mEq K+ losses in sweat and urine and the 282-288 mosmol.kg-1 plasma osmolalities. During the low-Na+ trial, plasma osmolality was maintained by a approximately equal to 1.3 l contraction of extracellular fluid (ECF) with the loss of approximately equal to 200 mEq Na+. However, in the other trials, approximately equal to 1.3 l of water was lost from the intracellular fluid. During the medium-Na+ trial, a loss of only approximately equal to 40 mEq Na+ maintained ECF volume, and during the high-Na+ trial, a gain of approximately equal to 160 mEq Na+ expanded the ECF by approximately equal to 0.8 l. However, corresponding changes in plasma volumes from -0.20 to 0.15 l had no effect on cardiovascular drift or thermoregulation. These data suggest that during prolonged exercise of moderate intensity under mild environmental conditions when sweat rates are approximately equal to 0.9 l.h-1, complete Na+ replacement maintains plasma volume and reduces dehydration, but when fluid intake matches sweat rate, has little effect on plasma osmolality.

Administration, Oral↗
PubMed1988

In vivo measurement of intracellular pH in human brain during different tensions of carbon dioxide in arterial blood. A 31P-NMR study.

The effect of changes in carbon dioxide tension in arterial blood upon intracellular pH in brain tissue was studied in seven healthy volunteers, aged 22-45 years. The pH changes were monitored by use of 31P nuclear magnetic resonance spectroscopy, performed on a whole-body 1.5 Tesla Siemens imaging system. The measurements were carried out during hyperventilation and with the subject breathing atmospheric air containing 5 vol. % and 7 vol. % carbon dioxide. Intracellular pH increased significantly during 15 min of hyper-ventilation and decreased significantly during 18 min respiration of air containing 7 vol. % carbon dioxide. The intracellular buffer capacity was estimated. These results suggest that the ventilation response to carbon dioxide is correlated to changes in intracellular fluid pH.

Adult↗
PubMed1999

Fluid-electrolyte balance during labor and exercise: concepts and misconceptions.

Body water and electrolyte balance are essential to optimal physiological function and health. During exercise, work, or high temperatures, a significant level of dehydration can develop, and the ratio of extracellular to intracellular fluid can change, despite an ample supply of water. Physical and cognitive performance are impaired at 1-2% dehydration, and the body can collapse when water loss approaches 7%. Because fluid needs and intakes vary, formulating one general guideline for fluid replacement is difficult. Knowing the amount of water lost in sweat may enable predicting fluid needs via mathematical models for industrial, athletic, and military scenarios. Sodium imbalance might result from excessive Na+ loss or from gross overhydration. In most work or exercise lasting < 3-4 hr, the major concern is that fluid be available to prevent heat-related illnesses, which can be prevented if fluid and electrolyte losses are balanced with intake, using the recommendations presented.

Adult↗
PubMed1985

Continuous measurement of fluid mobilization from ICF space following acute dehydration by dialyzation in dogs.

The changes of the distribution of body fluid following acute isotonic dialyzation were studied from the results of continuous monitoring of extracellular fluid volume and physiological parameters. An indicator of extracellular space, 51Cr-EDTA, was injected into splenonephrectomized dogs. After the equilibrium of tracer dilution was attained, 10 ml/kg of plasma water was isotonically withdrawn by means of a dialyzer of hollow fiber type. The volumes of extracellular fluid (ECF) and plasma (PV) were continuously monitored for 80 min and plasma osmolality was measured at 10 min intervals. At the 50-60th min after the fluid modification, the reduction of PV was only 3.8 ml/kg and that of ECF was 4.2 ml/kg. The continuous profile of ECF change showed a significant mobilization of water from intracellular fluid (ICF) soon after the dialyzation. It is concluded that, in the state of hypovolemia, plasma fluid is replenished with the transvascular fluid absorption from interstitial space and that, concomitantly, the reduction of ISF is restituted with the fluid mobilization from ICF into extracellular space within the early stage of 1 hr. Good linear correlation was found between the amount of mobilized water from ICF and the increment of plasma osmolality. An increase in osmotic force was considered the mechanism which caused the fluid shift. These findings suggest that the change in plasma osmolality is a good predictor of mobilized volume from ICF in hypovolemia. The effects of inverse fluid modification, i.e., isotonic infusion, were also compared.

Animals↗
PubMed1983

[Standardization in the study of water-containing spaces in patients with hypertension].

The study of hypertensive and normotensive patients has shown that as body weight increases the size of water-containing spaces decreases due to an improportional increase of the body surface area. The rise of total water content occurs mostly due to intracellular fluid. Patients with different sodium chloride consumption are characterized by different redistribution of extracellular fluid. Patients with low basal plasma renin activity, unlike those with normal renin activity, are characterized by different fluid distribution in watercontaining spaces and no interrelation between plasma renin activity and extracellular volumes.

Adult↗
PubMed1988

Analysis of burn injury by digital simulation.

A non-linear mathematical model for digital simulation of fluid distribution in burn patients during the first 48 h after injury is presented. The technique employed in the model construction is the system dynamic approach. A five-compartment model has been considered. The control mechanisms incorporated are adequate for describing the interactions between plasma and interstitial fluid and between the extra- and intracellular compartments. With the model we are able to analyse the dynamic behaviour of many variables, for example the plasma, interstitial, extra- and intracellular fluid volumes and the plasma and interstitial proteins in burn and non-burn areas. These values are very difficult to measure in daily clinical practice, although they indicate the actual state of a burn patient. The simulation results are compared with measured values in a series of patients from a burn unit in a general hospital.

Body Fluid Compartments↗
PubMed2000

Effect of cadmium on Pekin duck total body water, water flux, renal filtration, and salt gland function.

The following hypotheses were examined using Pekin ducks (Anas platyrhynchos) as a model for marine ducks: cadmium (Cd) intake affects (1) salt gland and/or kidney function of ducks and (2) osmoregulation differently in male and female ducks. Birds were fed 0, 50, or 300 microg Cd/g food. They were gradually acclimated to 450 mM NaCl and then drank 300 mM NaCl for 3 mo while salt gland secretion (SGS), glomerular filtration rate (GFR), total body water (TBW), and water flux (WF) were measured in ducks eating control and high-Cd diets. Cadmium ingestion did not markedly affect body mass, but significantly enlarged the salt glands and kidneys. Enhancement of kidney mass was greater in males. Cadmium ingestion did not affect TBW or WF, but tended to increase interstitial fluid space at the expense of intracellular fluid. Sex did not affect TBW, but males had greater WF. Birds that ate Cd diets, especially the higher Cd diet, exhibited renal tubular damage and lower GFR. Ducks that ate Cd had lower plasma sodium concentration and osmolality and, to activate SGS, required longer infusion of NaCl and larger increments

Animals↗
PubMed1999

Assessment of dry weight in hemodialysis: an overview.

Fluid balance is an integral component of hemodialysis treatments to prevent under- or overhydration, both of which have been demonstrated to have significant effects on intradialytic morbidity and long-term cardiovascular complications. Fluid removal is usually achieved by ultrafiltration to achieve a clinically derived value for "dry weight." Unfortunately, there is no standard measure of dry weight and as a consequence it is difficult to ascertain adequacy of fluid removal for an individual patient. Additionally, there is a lack of information on the effect of ultrafiltration on fluid shifts in the extracellular and intracellular fluid spaces. It is evident that a better understanding of both interdialytic fluid status and fluid changes during hemodialysis is required to develop a precise measure of fluid balance. This article describes the current status of dry weight estimation and reviews emerging techniques for evaluation of fluid shifts. Additionally, it explores the need for a marker of adequacy for fluid removal.

Biomarkers↗
PubMed1990

Determination of extracellular/intracellular fluid ratios from magnetic resonance images: accuracy, feasibility, and implementation.

This study determines the accuracy and feasibility of using localized spin-lattice (T1) relaxation time measurements from magnetic resonance (MR) images to follow changes in extracellular/intracellular fluid ratios in defined subvolumes of living tissue. A red blood cell suspension was used as a test system and a simple two-compartment model incorporating fast exchange was found to suffice for the conversion of T1 values to volume ratios. The technique requires the addition of gadolinium-DTPA to the model system to selectively enhance relaxation in the extracellular fluid space. No detectable amount of gadolinium-DTPA was found to enter the intracellular fluid space, and all magnetization decay plots obtained from both intracellular constituents and complete RBC suspensions consisted of a single exponential. Both of these results are compatible with assumptions underlying our physical model. The NMR-determined fluid ratio values were compared to those measured via the microhematocrit technique. Partial saturation image-mode determinations are strongly correlated to microhematocrit data (R2 = 0.945) and indicate that localized cell volume changes may be followed with a sensitivity of +/- 2.2%. These values compare favorably with those produced when nonimaging inversion-recovery techniques are used to determine the MR hematocrit (R2 = 0.962, sensitivity = +/- 1.1%). This technique, with modification, should be applicable to the comparison of ratios of extracellular/intracellular fluid volumes in structurally complex tissues where small subvolumes of homogeneous cell structure could be examined.

Body Fluids↗
PubMed1977

Cellular and extracellular dehydration, and angiotensin as stimuli to drinking in the common iguana Iguana iguana.

1. After water deprivation, the iguana promptly drank slightly more than enough water to restore the body fluids to isotonicity even under conditions of hypervolaemia. 2. In response to systemic injections of hypertonic solutions of NaCl and sucrose, the iguana drank and retained enough water to dilute the injected load to isotonicity irrespective of whether water was offered immediately or after 3 hr, and irrespective of whether the solute was administered I.V. or I.P. 3. Hypertonic solutions to glucose, urea, sorbitol and KCl caused little drinking. 4. The long latencies to drinking after hypertonic loads, which were not dependent on the nature of the solute, the route of administration or the dosage, were shown not to be a result of slow distribution of the solute throughout the body fluids. 5. Clearance of injected solutes via renal and extra-renal (nasal salt gland) routes was negligible during the 6 hr experimental period. 6. Measurements of plasma [Na], haematocrit, osmotic pressure and inulin space showed that the iguana drank, in response to cellular dehydration, enough water to restore the intracellular fluid volume to normal. 7. We conclude that, in response to substances which dehydrate cells, the iguana regulates its body osmolality precisely and efficiently provided it is able to do so by drinking. In this respect the responses of the iguana are similar to those of the nephrectomized rat since, in the short term, both rely exclusively on drinking to restore cellular water to normal. 8. The iguana also drinks in response to extracellular dehydration produced by hyperoncotic peritoneal dialysis, and in response to I.P. angiotensin II.

Angiotensin II↗
PubMedDate not supplied

[Body fluids during 120-day anti-orthostatic hypokinesia].

Body fluid variations were examined during 120-day antiorthostatic (-5 degrees) hypokinesia in 21 test subjects, 9 of which comprised a control group (Group 1). The remaining 12 subjects formed three groups (four subjects each) who received drugs to normalize mineral and lipid metabolism (Group 2), or performed specially developed exercises (Group 3), or were on the combined treatment (Group 4). Total body water (TBW), intracellular fluid volume (IFV), extracellular fluid volume (EFV), and EFV composition were measured by nuclear physical methods. Measurements were taken prior to exposure, on head-down tilt days 1, 60 and 120, and on recovery day 15. Body composition and K40 content were investigated before and after head-down tilt. The controls showed body dehydration that began on tilt day 1 at the expense of vascular fluid and continued by day 60 at the expense of interstitial fluid and by day 120 at the expense of IFV. Group 2 subjects exhibited variations that were similar to those of controls. Group 3 subjects were in better shape due to the beneficial effect of exercise which diminished as head-down tilt continued. In the recovery period the above changes regressed.

Blood Volume↗
PubMed1986

Potassium physiology.

Potassium is the most abundant exchangeable cation in the body. It exists predominantly in the intracellular fluid at concentrations of 140 to 150 meq/liter and in the extracellular fluid at concentrations of 3.5 to 5 meq/liter. The maintenance of the serum potassium concentration is a complex bodily function and results from the balance between intake, excretion, and distribution between intracellular and extracellular space. Ingested potassium is virtually completely absorbed from and minimally excreted through the intestine under nonpathologic circumstances. Renal excretion of potassium, which is the major chronic protective mechanism against abnormalities in potassium balance, depends on filtration, reabsorption, and a highly regulated distal nephron secretory process. Factors regulating potassium secretion include prior potassium intake, intracellular potassium, delivery of sodium chloride and poorly reabsorbable anions to the distal nephron, the urine flow rate, hormones such as aldosterone and beta-catecholamines, and the integrity of the renal tubular cell. The maintenance of distribution between the inside and outside of cells depends on the integrity of the cell membrane and its pumps, osmolality, pH, and the hormones insulin, aldosterone, beta 2-catecholamines, alpha-catecholamines, and prostaglandins. Both distribution across cell membranes and/or renal excretion of potassium may be altered by pharmacologic agents such as diuretics, alpha- and beta-catechol antagonists and agonists, depolarizing agents, and digitalis. Problems with hypokalemia and hyperkalemia can be analyzed on the basis of potassium physiology and pharmacology; proper treatment depends on an accurate analysis.

Aldosterone↗
PubMed1990

Effect of potassium solution on rehydration in rats: comparison with sodium solution and water.

Thermally dehydrated rats were given isotonic KCl, NaCl solution, or tap water ad libitum for 17 h and the differences of the restoration rate in fluid and cation were compared between the groups to elucidate the effect of Na+ and K+ ions on the replacement of each body fluid compartment during rehydration. When rats were provided with NaCl solution, the gains of fluid and Na+ exceeded the amounts lost during the dehydration period, while in the isotonic KCl and tap water groups fluid gain was 70% of the fluid lost during the dehydration period. The recovery of extracellular fluid (ECF) volume was 178% of the loss in the NaCl group and 50% in the KCl group. The Na+ concentration of the ECF was regulated closely in all groups. The recovery in intracellular fluid (ICF) volume did not differ significantly between groups and never exceeded the control level, but tended to be higher in the KCl group than in the NaCl group. These results indicated that in the ECF the regulation of Na+ concentration preceded that of volume while in the ICF, volume regulation had priority. In addition, the effect of K+ supplementation on the recovery of ICF volume after thermal dehydration was shown to be modest, unlike the effect of Na+ on the recovery of ECF volume.

Animals↗
PubMed1988

The involvement of extracellular calcium in hypoxic injury to the isolated rat liver.

Isolated perfused livers from fasted rats were subjected to 30 min of hypoxia followed by 60 min of reoxygenation. At a calcium concentration of 1.25 mmol/l in the perfusate, hypoxia induced injury as evidenced by a marked release of GPT and SDH into the perfusate and by an accumulation of calcium in the livers. Omission of calcium from the perfusate attenuated hypoxia-induced enzyme release by about 50% and prevented the increase of hepatic calcium completely. A complete protection of the liver against hypoxic injury was attained in the absence of calcium when Na2 EDTA was added. An influx of calcium from the extracellular to the intracellular fluid seems to be involved in but is not the sole cause of hypoxia-induced hepatic injury.

Animals↗
PubMed1976

Pharmacokinetics of coumarin upon i.v. administration in man.

The disposition pharmacokinetics of coumarin has been studied after i.v. administration in man, and might be described best by an open two-compartment model. Three dose sizes have been studied, 0.125, 0.2 and 0.25 mg/kg. The mean biological half-life was found to be 1.81, 1.45 and 1.49 h, respectively, for the three dose sizes. Coumarin is extensively distributed. The volume of the central compartment apparently comprises the extracellular and intracellular fluid. The study indicates dose-dependent (non-linear) pharmacokinetics with respect to distribution.

Adult↗