Changes In Body Water Research Articles

Can Changes in Body Mass and Total Body Water Accurately Predict Hyponatremia After a 161-km Running Race?

To relate changes in body mass, total body water (TBW), extracellular fluid (ECF), and serum sodium concentration ([Na]) from a 161-km ultramarathon to finish time and incidence of hyponatremia. Observational. : The 2008 Rio Del Lago 100-Mile (161-km) Endurance Run in Granite Bay, California. Forty-five runners. Pre-race and post-race body mass, TBW, ECF, and serum [Na]. Body mass and serum [Na] significantly decreased 2% to 3% (P < 0.001) from pre-race to post-race, but TBW and ECF were unchanged. Significant relationships were observed between finish time and percentage change in body mass (r = 0.36; P = 0.01), TBW (r = 0.50; P = 0.007), and ECF (r = 0.61; P = 0.003). No associations were found between post-race serum [Na] and percentage change in body mass (r = -0.04; P = 0.94) or finish time (r = 0.5; P = 0.77). Hyponatremia (serum [Na] < 135 mmol/L) was present among 51.2% of finishers. Logistic regression prediction equation including pre-race TBW and percentage changes in TBW and ECF had an 87.5% concordance with the classification of hyponatremia. Hyponatremia occurred in over half of the 161-km ultramarathon finishers but was not predicted by change in body mass. The combination of pre-race TBW and percentage changes in TBW and ECF explained 87.5% of the variation in the incidence of hyponatremia. Exercise-associated hyponatremia can occur simultaneously with dehydration and cannot be predicted by weight checks at races.

Effect of volume loading with 1 liter intravenous infusions of 0.9% saline, 4% succinylated gelatine (Gelofusine) and 6% hydroxyethyl starch (Voluven) on blood volume and endocrine responses: A randomized, three-way crossover study in healthy volunteers

To study the changes in blood volume and hormones controlling sodium and water homeostasis after infusions of 0.9% saline, Gelofusine (4% succinylated gelatin in 0.7% saline, weight-average molecular weight 30 kD), and Voluven (6% hydroxyethyl starch in 0.9% saline, weight-average molecular weight 130 kD) in healthy volunteers. Randomized, three-way crossover study. University teaching hospital. Ten healthy adult male volunteers. Volunteers received 1-L infusions of 0.9% saline, Gelofusine, and Voluven over 1 hr on three occasions. Body weight, hematocrit, serum biochemistry, and plasma concentrations of vasopressin, aldosterone, brain natriuretic peptide, and total renin were measured before infusion and hourly thereafter for 6 hrs. Changes in body water, blood volume, and extravascular fluid volume were calculated. Although changes in body weight (total body water) after the infusions were similar, blood volume expansion by the two colloids was significantly greater than that produced by 0.9% saline (p < .01). At the end of infusions, 68%, 21%, and 16% of the infused volumes of 0.9% saline, Gelofusine, and Voluven, respectively, had escaped from the intravascular space to the extravascular space. Over the 6 hrs, the magnitude and duration of blood volume expansion by the two colloids were similar (p = .70). There were no significant differences in urinary volume, osmolality, and sodium content after the three infusions. Hormonal changes were similar after the three infusions, with the increase in natriuretic peptide being transient. The reduction in aldosterone and total renin concentrations was more sustained. The effects of Gelofusine and Voluven were similar despite the 100 kD difference in weight-average molecular weight. Excretion of an acute fluid load containing sodium and chloride may be dependent on a sustained suppression of the renin-angiotensin-aldosterone system rather than on natriuretic peptides.

Comments on Baker et al.’s “Change in body mass accurately and reliably predicts change in body water after endurance exercise”

Comments on Baker et al.’s “Change in body mass accurately and reliably predicts change in body water after endurance exercise”

Bioreactance: A new tool for cardiac output and thoracic fluid content monitoring during hemodialysis

Outpatient hemodialysis therapy (HD) can be associated with hemodynamic compromise. Bioreactance has recently been shown to provide accurate, noninvasive, continuous, measurements of cardiac output (CO) and thoracic impedance (Zo) from which thoracic fluid content (TFC) can be derived assuming TFC=1000/Zo. This study was designed to evaluate the changes in TFC in comparison with the traditional indices of fluid removal (FR) and to understand the trends in CO changes in HD patients. Minute-by-minute changes in TFC and CO were prospectively collected using the bioreactance system (NICOM) in HD patients of a single unit. Changes in body weight (DeltaW), hematocrit (DeltaHct), and amount of FR were also measured. Twenty-five patients (age 77 +/- 11 years) were included. The TFC decreased in all patients by an average of 5.4 +/- 7.9 kohm(-1), weight decreased by 1.48 +/- 0.98 kg, and FR averaged 2.07 +/- 1.93 L over a 3- to 4-hour HD session. There were good correlations between DeltaTFC and DeltaW (R=0.80, P<0.0001) and FR (R=0.85, P<0.0001). DeltaHct (4.13 +/- 3.42%) was poorly correlated with DeltaTFC (R=0.35, P=0.12) and FR (R=0.40, P=0.07). The regression line between FR and TFC yielded FR=1.0024-0.1985TFC; thus, a 1 kohm(-1) change of Zo correlates with an approximately 200 mL change in total body water. The change in CO (-0.52 +/- 0.49 L/min m(2)) during HD did not correlate with FR (R=0.15, P=NS). Changes in TFC represented the monitored variable most closely related to FR. CO remained fairly constant in this stable patient cohort. Further studies in high-risk patients are warranted to understand whether TFC and CO monitoring can improve HD session management.

Effect of icodextrin dialysis solution on body weight and fat accumulation over time in CAPD patients

The purpose of this study was to analyse the changes of body composition and the effects of icodextrin dialysis solution over time on peritoneal dialysis (PD) in continuous ambulatory peritoneal dialysis (CAPD) patients. Among 183 incident patients, 75 patients finished a complete 36-month protocol. Clinical indices including daily glucose absorption and body composition, by bioelectrical impedance analysis (BIA), were measured in both groups (icodextrin group: 36 patients, non-icodextrin group: 39 patients) at the 1st (baseline), 12th, 24th and 36th months. There were significant increases in body weight and fat mass during the 36 months after initiation of CAPD. It was found that 78% of 3 years of weight gain occurred during the first year and 88% of weight gain at the end of the first year was fat mass gain. The icodextrin group showed a significantly lower percent of fat mass during the first 36 months (P < 0.05) and also less changes in body weight, fat mass, percent (%) fat mass, visceral fat area and waist/hip ratio at 1, 2 and 3 years than the non-icodextrin group. There were no significant changes in total body water (TBW), extra cellular fluid (ECF), oedema index and lean body mass (LBM) through comparable daily and ultrafiltration volume (UFV) between the two groups during the initial 3 years. Factors associated with the higher percent of fat mass gain over time on peritoneal dialysis were age, diabetes, gender (female) and non-icodextrin group (all, P < 0.01, generalized estimating equation). The application of icodextrin solution may be a better option to alleviate excessive fat gain over time for patients on PD.

Prophylactic Supplementation Of A Nano-sized Silica Mineral Antioxidant Complex On Changes In Clinical Safety Parameters And Body Water.

A nano-sized silica mineral antioxidant complex (MIC) is purported to alter cellular chemistry kinetics by delivering reduced hydrogen ions to the cell and reducing blood lactate levels. Further, the chemical structure of MIC supports osmotic traits that may impact levels of body water. PURPOSE: This study examined the effects of 7 days of prophylactic MIC supplementation on changes in clinical safety parameters and body water. METHODS: On three occasions, fifteen males (23.6 3.7 yrs, 180 8 cm, 85 11 kg, 16 5%) were tested using identical procedures under a control (CON), rice flour placebo (PLA) and microhydrin (MIC) condition. PLA and MIC supplementation was done in a prophylactic fashion over a seven day period (4 × 250 mg capsules/day). After controlling for diet and exercise habits, participants arrived fasted and donated a blood sample before and after supplementation for determination of serum and whole blood clinical safety markers. Total body (TBW), extracellular (ECW) and intracellular (ICW) water measurements using bioelectrical impedance spectroscopy were taken before and after supplementation and before and after a peak VO2 test. Repeated measures (2 × 3) ANOVA were completed on all variables using a p-value of 0.05. RESULTS: No significant changes (p>0.05) were found for any component of the lipid and metabolic panels, kidney/liver enzymes, markers of protein breakdown and complete blood counts. Supplementation resulted in no change in TBW (p=0.43), ECW (p=0.65) and ICW (p=0.38) after each condition. Similarly, no significant group x time interactions were found for ECW (p=0.19), although TBW (p=0.09) and ICW (p=0.052) tended to change. Significant time effects for TBW (p<0.01) and ICW (p<0.001) were found. Within-group analysis of post-exercise body water revealed significant increases in ICW in PLA (+0.51 L; p<0.005) and MIC (+0.43 L; p<0.01) along with a significant increase in TBW for MIC (+0.59 L; p<0.01). CONCLUSION: Clinical safety markers did not change after seven days of prophylactic MIC supplementation and was well tolerated. MIC supplementation did not stimulate any changes in body water compartments, while immediate increases in TBW and ICW after maximal exercise were found. Post-exercise ICW levels increased in PLA and MIC while TBW only increased in MIC. Supported by RBC Life Sciences

Body composition and aging.

he changes in composition of the aging T human body is of both gerontologic and geriatric interest and reflects genetic factors and environmental factors such as physical activity, nutrition, and disease, as well as the normal aging processes. In the study of normal aging, that is, aging per se, long-term trends in body compartments are important. In the field of clinical geriatrics, body composition is also of great interest in the study of obesity, malignant disease, and clinical pharmacology and biochemistry. Changes of body cell mass, body fat, and body water occur frequently in both disease and aging. These changes in body compartments may alter the pharmacokinetic and pharmacodynamic properties of drugs used in old age. The amount of body fat and the amount of body cell mass are important parameters when judging the net effect of energy intake and expenditure. Thus, examination of body composition adds information to an overall picture of nutrition of the elderly. Such overall knowledge also requires data on actual dietary habits of elderly populations in different countries. Not only intakes of energy, nutrients, and food items are important, but also distribution and composition data on meals and data on medical, psychologic, and socioeconomic conditions are prerequisites for the analysis of the relationship between requirements and actual intake. The need for broad epidemiologic approaches to these questions is obvious. Concepts The frequently used concept of “lean body mass” has two meanings, namely, body weight minus neutral fat, but including some lipids such as phospholipids, the exact amount of which is unknown. Lean body mass is, according to this meaning, similar to, but not identical with, fat-free body mass. Although lean body mass has a relatively constant specific gravity, from a biologic point of view it is a heterogenous body component with varying energy consumption, since it also comprises-apart from body cel I massfat-f ree ext race1 I u lar solids and extracellular water. Furthermore, since the water content of adipose tissue may show great variation and is also difficult to estimate, the definition of lean body mass should be body weight minus body fat, that is, fat-free mass. Many workers, nowadays, however, avoid the concept of a lean body mass and fat-free mass, since the body is not a simple two-compartment system. Moore and collaborators’ many years ago suggested that the concept of body cell mass would provide a better estimate than lean body mass of metabolically active tissue. Many workers now prefer to divide body weight into body cell mass, extracellular water, body fat, and fat-free extracellular solids that are present primarily in bone and connective tissuea2 For a review of the concepts of body compartments, see references 1, 3, 4, and 5.

Change in body mass accurately and reliably predicts change in body water after endurance exercise

This study tested the hypothesis that the change in body mass (DeltaBM) accurately reflects the change in total body water (DeltaTBW) after prolonged exercise. Subjects (4 men, 4 women; 22-36 year; 66 +/- 10 kg) completed 2 h of interval running (70% VO(2max)) in the heat (30 degrees C), followed by a run to exhaustion (85% VO(2max)), and then sat for a 1 h recovery period. During exercise and recovery, subjects drank fluid or no fluid to maintain their BM, increase BM by 2%, or decrease BM by 2 or 4% in separate trials. Pre- and post-experiment TBW were determined using the deuterium oxide (D(2)O) dilution technique and corrected for D(2)O lost in urine, sweat, breath vapor, and nonaqueous hydrogen exchange. The average difference between DeltaBM and DeltaTBW was 0.07 +/- 1.07 kg (paired t test, P = 0.29). The slope and intercept of the relation between DeltaBM and DeltaTBW were not significantly different from 1 and 0, respectively. The intraclass correlation coefficient between DeltaBM and DeltaTBW was 0.76, which is indicative of excellent reliability between methods. Measuring pre- to post-exercise DeltaBM is an accurate and reliable method to assess the DeltaTBW.

Effect of atorvastatin and hydroxychloroquine combination on blood glucose in alloxan-induced diabetic rats

Objective:To evaluate the antihyperglycemic activity of atorvastatin and hydroxychloroquine combination in alloxan-induced diabetic rats.Materials and Methods:Alloxan induced diabetic Wistar male rats were randomized into six groups of 6 rats each. (Normal rats, diabetic control, atorvastatin (ATV), hydroxychloroquine (HCQ), ATV 5 mg /kg + HCQ 100 mg/kg, and ATV 10 mg/kg + HCQ 200 mg/kg). The rats were treated for 9 days and blood samples were collected at baseline and end of therapy. These samples were analyzed for plasma glucose by autoanalyzer. Changes in body weight, water, food intakes and total protein content were also recorded.Results:Atorvastatin and hydroxychloroquine alone and in combination reported significant fall in blood glucose level from baseline. Fall in glucose level was significantly more in high dose combination of atorvastatin and hydroxychloroquine (ATV: 10 mg/kg + HCQ: 200 mg/kg) as compared to other study treatment groups (ATV: 17% Vs HCQ: 7% Vs ATV 5mg/kg + HCQ 100mg /kg: 14% Vs ATV 10mg/kg + HCQ 200mg /kg: 21%; p<0.01). ATV and HCQ individually and in combination also improved the body weight loss. The weight gain was significantly more in combination treated rats as compared to positive control group and greater than those who received atorvastatin and hydroxychloroquine alone. Rats treated with the combination also reported significant decrease in food intake and significant increase in total protein.Conclusion:Increased hypoglycemic effect in combination may be due to potentiation or synergism between HCQ and ATV. Further studies are required to demonstrate clinically significant antidiabetic effect.

Comments on Baker et al.'s “Quantitative analysis of serum sodium concentration after prolonged running in the heat”

to the editor: Baker et al. ([1][1]) tested the Nguyen-Kurtz equation's ([4][2]) predictive powers for serum [Na]. Briefly, the N-K equation is a mass-balance approach to predicting changes in serum [Na]. Given a starting serum [Na] and total body water and then accounting for changes in body water

Change in Body Weight is an Accurate and Reliable Predictor of Change in Body Water

Change in Body Weight is an Accurate and Reliable Predictor of Change in Body Water

The changes in body composition and body water in the first six months of dialysis.

The changes in body composition and body water in the first six months of dialysis.

Fluid and electrolyte management in term and preterm neonates

Disorders of fluid and electrolyte are common in neonates and a proper understanding of the physiological changes in body water and solute after birth is essential to ensure a smooth transition from the aquatic in-utero environment. The newborn kidney has a limited capacity to excrete excess water and sodium and overload of fluid or sodium in the first week may result in morbidities like necrotizing enterocolitis, patent ductus arteriosus and chronic lung disease. Simple measures like use of transparent plastic barriers, coconut oil application, caps and socks are effective in reducing insensible water loss. Guidelines for the management of fluids according to birth weight, day of life and specific clinical conditions are provided in the protocol.

An improved method to compute the solute and water derangements of hyperglycaemia

Evaluation and treatment of hyperglycaemic hyponatremia, being quantitatively inaccurate, is open to new advancements. We herein describe the improvement of previous calculations of glucose appearance (G(A)), solute and solvent changes. From G(A) we derive the predicted plasma sodium concentration (PNa(G)), assuming no change in total body water (TBW), but only water shift from cells to the extracellular space (ECV). This assumption is validated by the respective solute ratios (PCl/PNa) unchanged from normal values, as well as the ratios between actual and normal solute concentrations (PNa(1)/PNa(0), PCl(1)/PCl(0)), identical for all solutes. When the assumption is met, G(A) can be exactly calculated. When the ratios are different from normal, they indicate the presence of a mixed abnormality due to a loss either of sodium, or sodium and water. These are estimated by computing the difference between PNa(G) and the actual PNa measured (PNa(1)). PNa(1) approximately equal PNa(G) if TBW and Na are unchanged, PNa(1) < PNa(G) in the presence of prevalent Na depletion, PNa(1) > PNa(G )when volume depletion prevails. In the first circumstance the ECV expansion is exactly established by appropriate mathematical formulas, in the latter conditions either Na or volume depletion are empirically estimated with algebric expressions. These equations were validated on computer-simulated models, and applied to 49 subjects with plasma glucose concentration >15 mM/L. G(A) and PNa(G) were computed, and, with the same formulas used in computer-simulated experiments, we calculated water and Na deficits. The PNa measured after correction of hyperglycaemia was correctly predicted (R(2) = 0.63, P < 0.0001). This method provides a firm ground to select the correct equation to accurately estimate the initial conditions of hyperosmolar hyperglycaemia, significantly improving its quantitative correction.

Effect of Hydration State on Strength, Power, and Resistance Exercise Performance

Although many studies have attempted to examine the effect of hypohydration on strength, power, and high-intensity endurance, few have successfully isolated changes in total body water from other variables that alter performance (e.g., increased core temperature), and none have documented the influence of hypohydration on an isotonic, multiset, multirepetition exercise bout typical of resistance exercise training. Further, no investigations document the effect of hypohydration on the ability of the central nervous system to stimulate the musculature, despite numerous scientists suggesting this possibility. The purposes of this study were to examine the isolated effect of hydration state on 1) strength, power, and the performance of acute resistance exercise, and 2) central activation ratio (CAR). Seven healthy resistance-trained males (age = 23 +/- 4 yr, body mass = 87.8 +/- 6.8 kg, body fat = 11.5 +/- 5.2%) completed three resistance exercise bouts in different hydration states: euhydrated (EU), hypohydrated by approximately 2.5% body mass (HY25), and hypohydrated by approximately 5.0% body mass (HY50). Investigators manipulated hydration status via exercise-heat stress and controlled fluid intake 1 d preceding testing. Body mass decreased 2.4 +/- 0.4 and 4.8 +/- 0.4% during HY25 and HY50, respectively. No significant differences existed among trials in vertical jump height, peak lower-body power (assessed via jump squat), or peak lower-body force (assessed via isometric back squat). CAR tended to decrease as hypohydration increased (EU = 95.6 +/- 4.9%, HY25 = 94.0 +/- 3.1%, HY50 = 92.5 +/- 5.1%; P = 0.075, eta(p)(2) = 0.41). When evaluated as a function of the percentage of total work completed during a six-set back squat protocol, hypohydration significantly decreased resistance exercise performance during sets 2-3 and 2-5 for HY25 and HY50, respectively. These data indicate that hypohydration attenuates resistance exercise performance; the role of central drive as the causative mechanism driving these responses merits further research.

Hydration abnormalities in Nigerian patients on chronic hemodialysis

The state of hydration affects the outcomes of chronic dialysis. Bioelectrical impedance analysis (BIA) provides estimates of body water (V), extracellular volume (ECFV), and fat-free mass (FFM) that allow characterization of hydration. We compared single-frequency BIA measurements before and after 14 hemodialysis sessions in 10 Nigerian patients (6 men, 4 women; 44+/-7 years old) with clinical evaluation (weight removed during dialysis, presence of edema) and with estimates of body water obtained by the Watson, Chertow, and Chumlea anthropometric formulas. Predialysis and postdialysis values of body water did not differ between BIA and anthropometric estimates. However, only the BIA estimate of the change in body water during dialysis (-0.8+/-2.9 L) did not differ from the corresponding change in body weight (-1.3+/-3.0 kg), while anthropometric estimates of the change in body water were significantly lower, approximately one-third of the change in weight. Bioelectrical impedance analysis correctly detected the intradialytic change in body water content (the ratio V/Weight) in 79% of the cases, while anthropometric formula estimates of the same change were erroneous in each case. Compared with patients with clinical postdialysis euvolemia (n=7), those with postdialysis edema (n=5) had higher values of postdialysis BIA ratios V/FFM (0.77+/-0.01 vs. 0.72+/-0.03, p<0.01) and ECFV/V (0.53+/-0.02 vs. 0.47+/-0.06, p<0.05), respectively. Bioelectrical impedance analysis appeared to underestimate body water and extracellular volume in a patient with massive ascites and bilateral pleural effusions. Anthropometric formulas are not appropriate for evaluating the state of hydration in patients on chronic hemodialysis. In contrast, BIA provides estimates of hydration agreeing with clinical estimates in the same patients, although it tends to underestimate body water and extracellular volume in patients with large collections of fluid in central body cavities.

Blood Volume Response to Physical Activity and Inactivity

Data from both cross-sectional and longitudinal studies provide compelling evidence that circulating blood volume can be influenced by regular physical activity or inactivity. Expansion or contraction of plasma volume can account for most of the alteration in circulating blood volume during the initial 1 to 2 weeks of changing physical activity patterns; after this time, altered blood volume may be distributed equally between plasma and red cell volumes. Alterations in circulating blood volume that accompany changes in physical activity represent a net change in total body water and solutes that are associated with increased or decreased water intake and urine volume and solute output. The mechanism of altered urine output appears to be a modified renal tubular reabsorption of sodium. The expansion of blood volume that accompanies physical activity provides advantages of greater body fluid for heat dissipation (sweating) and thermoregulatory stability as well as larger vascular volume for greater cardiac filling and stroke volume and cardiovascular stability during exercise and orthostatic challenges. The opposite is true when blood volume is reduced during periods of relative physical inactivity. The observation that underlying mechanisms for alteration in blood volume with physical activity and inactivity are similar but respond directly opposite suggests that they are intricately related. These relations have implications as to a mechanism by which physical activity and fitness may be protective against reduced blood volume and subsequent development of cardiovascular disease associated with aging.

Effects of acclimation on water and electrolitic disbalance in soldiers during exertional heat stress

Exertional heat stress is a common problem in military services. The aim of this study was to exemine changes in body water and serum concentrations of some electrolites in soldiers during exertional heat stress (EHST), as well as effects of 10-day passive or active acclimation in a climatic chamber. Forty male soldiers with high aerobic capacity, performed EHST either in cool (20 degrees C, 16 degrees C WBGT-wet bulb globe temperature), or hot (40 degrees C, 25 degrees C WBGT) environment, unacclimatized, or after 10 days of passive or active acclimation. The subjects were allowed to drink tap water ad libitum during EHST. Mean skin (Tsk) and tympanic (Tty) temperatures and heart rates (HR) measured physiological strain, while sweat rate (SwR), and serum concentrations of sodium, potassium and osmolality measured changes in water and electrolite status. Blood samples were collected before and immediately after the EHST. Exertional heat stress in hot conditions induced physiological heat stress (increase in Tty, HR, and SwR), with significant decrease in serum sodium concentration (140.6 +/- 1.52 before vs. 138.5 +/- 1.0 mmol/l after EHST, p < 0.01) and osmolality (280.7 +/- 3.8 vs. 277.5 +/- 2.6 mOsm/kg, p < 0.05) in the unacclimatized group. The acclimated soldiers suffered no such effects of exertional heat stress, despite almost the same degree of heat strain, measured by Tty, HR and SwR. In the trained soldiers, 10-day passive or active acclimation in a climatic chamber can prevent disturbances in water and electrolitic balance, i.e. decrease in serum sodium concentrations and osmolality induced by exertional heat stress.

Estimation of Acute Fluid Shifts Using Bioelectrical Impedance Analysis in Horses

Multi-frequency bioelectrical impedance analysis (MF-BIA) has been used to evaluate extracellular fluid volume (ECFV), but not fluid fluxes associated with fluid or furosemide administration in horses. If able to detect acute changes in ECFV, MF-BIA would be useful in monitoring fluid therapy in horses. The purpose of this study was to evaluate the ability of MF-BIA to detect acute fluid compartment changes in horses. We hypothesized that MF-BIA would detect clinically relevant (10-20%) changes in ECFV. Six healthy mares were used in the study. This is an original experimental study. Mares were studied in 3 experiments: (1) crystalloid expansion of normally hydrated subjects, (2) furosemide-induced dehydration followed by crystalloid administration, and (3) acute blood loss followed by readministration of lost blood. MF-BIA measurements were made before, during, and after each fluid shift and compared to known changes in volume calculated based on the intravenous fluids that were administered in addition to urinary fluid losses. Mean errors between MF-BIA estimated change and known volume change were compared using nonparametric analysis of variance. Estimated ECFV pre- and post-fluid administration similarly were compared. The level of statistical significance was set at P < .05. Results of the study revealed a statistically significant change in ECFV and total body water during crystalloid expansion and dehydration. Statistically significant changes were not observed during blood loss and administration. Mean errors between MF-BIA results and measured net changes were small. MF-BIA represents a practical and accurate means of assessing acute fluid changes during dehydration and expansion of ECFV using isotonic crystalloids with potential clinical applications in equine critical care.

Estimation of Acute Fluid Shifts Using Bioelectrical Impedance Analysis in Horses

Background: Multi‐frequency bioelectrical impedance analysis (MF‐BIA) has been used to evaluate extracellular fluid volume (ECFV), but not fluid fluxes associated with fluid or furosemide administration in horses. If able to detect acute changes in ECFV, MF‐BIA would be useful in monitoring fluid therapy in horses. Hypothesis: The purpose of this study was to evaluate the ability of MF‐BIA to detect acute fluid compartment changes in horses. We hypothesized that MF‐BIA would detect clinically relevant (10–20%) changes in ECFV. Animals: Six healthy mares were used in the study. Methods: This is an original experimental study. Mares were studied in 3 experiments: (1) crystalloid expansion of normally hydrated subjects, (2) furosemide‐induced dehydration followed by crystalloid administration, and (3) acute blood loss followed by readministration of lost blood. MF‐BIA measurements were made before, during, and after each fluid shift and compared to known changes in volume calculated based on the intravenous fluids that were administered in addition to urinary fluid losses. Mean errors between MF‐BIA estimated change and known volume change were compared using nonparametric analysis of variance. Estimated ECFV pre‐ and post‐fluid administration similarly were compared. The level of statistical significance was set at P &lt; .05. Results: Results of the study revealed a statistically significant change in ECFV and total body water during crystalloid expansion and dehydration. Statistically significant changes were not observed during blood loss and administration. Mean errors between MF‐BIA results and measured net changes were small. Conclusions and Clinical Importance: MF‐BIA represents a practical and accurate means of assessing acute fluid changes during dehydration and expansion of ECFV using isotonic crystalloids with potential clinical applications in equine critical care.