Assessment Of Fluid Volume Status Research Articles

UHAS-MIDA Software Package: Mass Isotopomer Distribution Analysis-Applying the Inverse Matrix for the Determination of Stable Isotopes of Chromium Distribution during Red Blood Cell Labelling

Clinical assessment of fluid volume status in children during malaria can be taxing and often inaccurate. During malaria, changes in fluid volume are rather multifarious and estimating this parameter, especially in sick children is very challenging for clinicians who frequently rely on indices such as long capillary refill times, tachycardia, central venous pressure and decreased urine volume as guides. Here, we present the UHAS-MIDA, an open-source software tool that calculates the red blood cell (RBC) concentration and blood volume during malaria in children determined using a stable isotope of chromium (53Cr as the label) by gas chromatography-mass spectrometry in selective ion monitoring (GC/MS-SIM) analysis. A key component involves the determination of the compositions of the most abundant naturally occurring isotopes of Cr (50Cr, 52Cr, 53Cr), and converting the proportions into a 3 × 3 matrix. To estimate unknown proportions of chromium isotopic mixtures from the measured abundances of three ions, an inverse matrix was calculated. The inverse together with several inputs is then used to calculate the corrected MS ion abundances. Thus, we constructed the software tool UHAS- MIDA using HTML, CSS/Bootstrap, JavaScript, and PHP scripting languages. The tool enables the user to efficiently determine RBC concentration and fluid volume. The source code, binary packages and associated materials for UHAS-MIDA are freely available at https://github.com/bentil078/Abaye-et-al_UHASmida

Knee-to-knee Bioimpedance Measurements to Monitor Changes in Extracellular Fluid in Haemodynamic-unstable Patients During Dialysis.

The feasibility of bioimpedance spectroscopy (BIS) techniques for monitoring intradialytic changes in body fluids is advancing. The aim of this study was to compare the knee-to-knee (kkBIS) with the traditional whole-body (whBIS) with respect to continuous assessment of fluid volume status in hemodialysis patients. Twenty patients divided into two groups, hemodynamically stable and unstable, were recruited. Bioimpedance data from two different electrodes configurations (hand-to-foot and knee-to-knee) were collected and retrospectively analysed. A good correlation between the two methods with respect to changes in extracellular resistance (Re) and Re normalized for ultrafiltration volume (ΔRe/UFV) with p < 0.001 was observed. The relationship between relative change (%) in ΔRe and that in patient weight was most notable with kkBIS (4.82 ± 3.31 %/kg) in comparison to whBIS (3.69 ± 2.90 %/kg) in unstable patients. Furthermore, results based on kkBIS showed a reduced ability of the thigh compartments to keep up with the volume changes in the trunk for unstable patients. kkBIS provided a comparable sensitivity to whBIS even in patients at risk of intradialytic hypotension while avoiding the need for the complex implementation imposed by whBIS or other configurations.

Dry weight targeting: The art and science of conventional hemodialysis.

Fluid volume overload is common and is associated with adverse outcomes in hemodialysis patients. Practicing physicians individually manage fluid volume balance in their dialysis patients according to blood pressure, interdialytic weight gain, cardiac function, nutritional status, and other comorbidities. However, accurate assessment of fluid volume status remains a concern. Indicators of dry weight target have been explored further with newer concepts and technologies. In general, total body water comprises approximately 50%-60% of adult body weight (range, 45%-75%), and water comprises 73.3% of lean body mass. The standard hydration status between intracellular water and extracellular water is maintained at a ratio of 62:38 in healthy adults, which, however, is influenced universally by body cell volume driven by age and muscle mass. Fluid volume imbalance in dialysis patients also is characterized primarily by decreased body cell mass associated with aging and muscle attenuation, as well as excess extracellular water content associated with sodium retention, which may be associated with the reserve capacity for volume overload. Indeed, dialysis patients with a leaner body mass have a higher prevalence of hypertension, poorer hypertension control, and greater left ventricular hypertrophy. Understanding of these body composition changes by aging and sarcopenia can aid clinical decision making in the dry weight assessments in dialysis patients. Advising patients with consistently high interdialytic weight gain to practice salt restriction and providing appropriate nutritional support for malnourished patients with downward trajectory in their dry weight would be of great help to achieve optimal fluid volume status.

Hyponatremia in children with acute respiratory infections: A reappraisal.

Hyponatremia (<135 mmol/L), typically associated with an elevated anti-diuretic hormone level, is common among children admitted with bronchiolitis, pneumonia, or pulmonary exacerbation of cystic fibrosis. The main consequences of acute hyponatremia include cerebral edema and Ayus-Arieff pulmonary edema. A widespread belief is that, in children with pneumonia or bronchiolitis, hyponatremia results from inappropriate anti-diuresis. By contrast, the pathogenic role of extracellular fluid volume depletion or decreased effective circulating blood volume is underscored. Considering the prevalence of hyponatremia, sodium determination is advised on admission in children diagnosed with bronchiolitis, pneumonia, or pulmonary exacerbation of cystic fibrosis. There is no necessity to do anything beyond reassessing the appropriateness of fluid therapy in cases with mild (130-134 mmol/L) hyponatremia. In children with sodium <130 mmol/L, the underlying etiology is sometimes evident from history and physical findings. Given that clinical assessment of fluid volume status is difficult in hyponatremia, further laboratory evaluation is often required in these patients. An increase in sodium level ≤6 mmol/L per day is currently considered the therapeutic goal in all cases. Emergency correction with a 2 mL/kg body weight bolus of 3.0% saline over 10-15 min intravenously is advised in cases with severe symptoms due to hyponatremia and in cases with symptoms, even if mild, due to a rapid-onset (<48 h) of hyponatremia (two additional doses are administered if the patient's condition does not improve).

TFC (Thoracic Fluid Content): A New Parameter for Assessment of Changes in Chest Fluid Volume

Clinical assessment of cardiac status can be difficult and incomplete without an assessment of fluid volume status, especially of the lungs. Now, a new parameter is available, thoracic fluid content (TFC). It is an indicator of total fluid volume, both intracellular and extracellular. Because it is measured noninvasively using impedance cardiography (ICG), it could be a welcome addition to the physician's assessment. An evaluation of TFC was performed beginning with 1) an examination of chest impedance (Z) as an accurate means of following fluid changes, 2) the relationship of TFC to Z using both loop and spot electrodes, and 3) clinical applications of TFC. In 1) 12 dogs, Z was superior (r = 0.935, P < 0.006) to 10 traditional hemodynamic and gas transfer parameters in trending a lactated Ringer's infusion; 2) a plastic model, changes in TFC values derived from Z measurements using both loop and spot electrodes were virtually identical and paralleled infused saline (r = 0.999, P < 0.001); 3) the clinical setting, TFC trended fluid changes well. From these results, we conclude that TFC is a reliable measurement of chest fluid status and of changes in that fluid. Along with cardiac index (CI), also provided by the ICG monitor, TFC can be very helpful to the clinician.

Non-invasive assessment of fluid volume status in theinterstitium after haemodialysis

During dialysis excess fluid is removed from uraemic patients.The excess fluid is mainly located in the skin and subcutaneoustissues. In this study we wished, with two non-invasivetechniques, the IM (impression method) and BIA (bioimpedanceanalysis), to study what mechanical (IM) and electrical cellularmembrane (BIA) effects the fluid withdrawal has on thesetissues. The IM measures the resistive force of the tissues whenmechanically compressed. From the force curve two parametersare calculated, the F(0), indicative of interstitial tissuepressure and the FT corresponding to the translocation of tissuefluid (interstitial movable water).The BIA phase angle shift (ϕ), i.e. geometrical angulartransformation of the ratio between reactance and resistance,which has been associated with cellular membrane function, wasused as a measurement of electrical cellular membrane effects.Twenty patients were studied before and after haemodialysismeasuring the F(0), FT and ϕ. The results showed that thepatients lost a median of 3.7 kg during the haemodialysis. F(0)increased until after dialysis, but did not reach significantvalues, whereas FT increased significantly after dialysis,p < 0.001, as compared with before. After a peak at one hourpostdialysis the FT value returned to predialysis values at fourhours after termination of dialysis. Also ϕ increased frombefore to after dialysis, p < 0.001, but already after one hour itreturned to predialysis values.It is common knowledge that dialysis alters the dynamics of fluidin the interstitium of the skin and subcutis. We conclude that theimpression method is sensitive enough to detect and chroniclethese changes. Furthermore, with the BIA, (phase angle) signs ofchanges in the electrical properties of the tissues, possiblyreflecting cellular membrane function, could be detected.

The use of postural vital signs in the assessment of fluid volume status

Postural or orthostatic vital signs, although frequently used in many clinical settings to aid in the diagnosis of fluid volume disturbance, can be a source of confusion. Practitioners often have questions about how to perform the test and may be uncertain about what results mean in various clinical situations. Some of this confusion is reflected in the literature, where studies on normal orthostatic responses seem to contradict clinically used parameters of "normal," and where very few studies appear on evaluating unusual responses as indicators of patients' fluid volume status. A review of existing literature is presented, in which relevant data are reviewed in terms of their impact on the use of this clinical sign. Recommendations regarding the use of the orthostatic test are given.

Preliminary experience with portable digital imaging for intensive care radiography

A digital radiography system based on reusable, photostimulable phosphor technology was evaluated in approximately 3,500 portable chest radiographs of patients in an intensive care unit. The system functioned well in this application. No major problems were encountered in the visualization of tubes or catheters or in the detection of pneumothoraces. Assessment of fluid volume status or the presence of small pleural effusions, especially when these were bilateral, was initially somewhat difficult but became easier as investigators became familiar with the system. Radiologists were quicker than nonradiologists to accept the minimized two-on-one display format. Critical evaluation of the overall performance of digital systems such as this one is needed for a better definition of the system's strengths and weaknesses. Specifically, statistical analyses of the ability to detect disease states such as pneumothoraces, interstitial lung disease, lung nodules, and pleural abnormalities need to be performed.