Body Fluid Compartments Research Articles

Body Water Compartment and Sympathovagal Balance: Association with Visuomotor Retention in Young Adults

Cognitive functions are important for visuomotor learning and are associated with physiological factors such as body fluid compartment and cardiovascular reactivity. Previous studies found that body fluid compartment is associated with brain blood flow, which is regulated via sympathovagal balance. However, more evidence is needed to determine whether body fluid compartment and cardiovascular reactivity are associated with visuomotor learning. The purpose of this study was to explore the relationship of body fluid compartment and cardiovascular reactivity to visuomotor learning. We hypothesized that these physiological factors are associated with overall learning retention using upper extremity (including feedforward, volitional, and feedback conditions). Methods: Thirty young adults (12 males, 24.6 ± 3.9 years, right hand dominant) participated in this study. Participants tracked a sinusoidal wave with left arm at pre-test, learning, and post-test sessions on the first visit and at retention test session on the second visit seven days later. Participants performed one set of nine trials during each test and five sets of three trials during learning. Resistance and wave velocity were different in each trial. Learning error was calculated by the averaged absolute distance between the tracking line and the target line. Heart rate (HR), systolic blood pressure (SBP), and low to high frequency power ratio of heart rate variability (LF/HF) were continuously recorded during baseline before pre-test and during tests and learning. We analyzed participants’ extracellular to intracellular body water ratio (ECW/ICW) using an InBody body composition analyzer and tested their cognitive function with Picture Sequence Memory (PSMT), Pattern Comparison Processing Speed, Dimensional Change Card Sort, Flanker Inhibitory Control and Attention, and List Sorting Working Memory Tests from NIH Cognitive Toolbox. Data were statistically analyzed using linear regression analysis and quartile analysis. Results: ECW/ICW was associated with young adults’ ability to retain visuomotor learning after one week (R2 = 0.138, p = 0.043), whereas HR, SBP, and LF/HF at each session were not significantly associated with visuomotor retention. No differences were found in pre-test error among quartiles of five cognitive tests. Significant differences in retention error among quartiles were only found in PSMT, with participants scoring in the highest quartile of PSMT having lower SBP during the first visit and lower retention error compared to the lowest quartile. This finding suggests that young adults with better episodic memory were less stressed during learning and had better visuomotor retention. Conclusion: These findings support that ECW/ICW is associated with not only cognitive function but also visuomotor retention. In addition, cardiovascular reactivity during visuomotor learning may provide information for retention behavior. Relationship of body water compartment and sympathovagal balance to feedforward and feedback conditions in learning will be further discussed. Research Support: This study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development: R01HD084645, R01HD082109. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Plasma Volume Oscillations during Fluid Therapy in Humans

Introduction: Oscillations are frequently observed on plasma dilution curves during intravenous fluid therapy. This study aimed to examine how common these oscillations are and what they represent. Methods: Fourier transforms were used to analyze the residuals obtained during fitting of a volume kinetic model to 269 plasma dilution curves. Oscillating patterns were identified in two-thirds of the fluid infusion experiments. Results: The wave frequency usually had a dominating frequency of 1 h or multiples thereof. The wave amplitudes varied between 1% and 4% of the plasma volume. The “peak-to-peak” amplitudes were then twice as large, which corresponded to blood volume changes of 60–240 mL. A population kinetic analysis of the distribution of infused fluid between body fluid compartments was then applied to search for clues that could explain the oscillations. This analysis showed that amplitudes >1.5% were associated with doubled turnover of fluid in a fast-exchange interstitial fluid compartment and, together with data on plasma albumin, suggested that oscillations might represent bursts of efferent lymph. Conclusions: Oscillations with very low frequency were often observed on plasma dilution-time curves obtained during fluid therapy. They were associated with fast turnover of interstitial fluid and can possibly have resulted from accelerated lymphatic flow.

A stochastic multicompartment model of hemostasis and oxygenation during trauma resuscitation as a platform for in silico trials of transfusion

Abstract Uncontrolled hemorrhage accounts for up to 40% of trauma related mortality, and approximately 30% of trauma related deaths occur in the hospital within the first 1-4 hours of injury. The Advanced Trauma Life Support (ATLS) guidelines still recommend initial resuscitation with crystalloid fluid as an integral part of maintaining or restoring hemodynamic stability, but are starting to recognize the role of early resuscitation with blood products in patients with evidence of Class III and IV hemorrhage, in line with recent clinical trial and observational data. Although there is a growing body of evidence that early transfusion with blood products may be associated with improved survival compared with crystalloid infusion, the optimal transfusion strategy still remains unclear and is being actively investigated in clinical trials. In silico models of resuscitation offer a means to evaluate the effectiveness and safety of resuscitation protocols, including effects on body fluid compartment volumes, tissue oxygenation, and hemostatic factors. Here we describe our work extending earlier deterministic models of trauma resuscitation to incorporate hemodynamic, hemostatic, resuscitation, biomarker, and tissue-oxygenation domains into a single comprehensive model. Additionally, this model expands upon previous deterministic models to create a stochastic computational model of hemostatic resuscitation that accounts for variations in blood component composition and temporal features of transfusion therapy. Using this stochastic model, an in silico trial was piloted to compare conventional component therapy, i.e. red cell, platelet and plasma components, to cold-stored whole blood using the following starting assumptions: patient weight of 81.3±21.8 kg, hematocrit of 41.8±4.3%, initial bleeding rate between 50 and 150 mL/min, systolic blood pressure of 125±18 mmHg, fibrinogen of 293±88 mg/dL, international normalized ratio of 1.0±0.1 and platelet count of 239±62x109/L, with blood component and whole blood constituent distributions based on laboratory quality control data. This in silico trial demonstrated that resuscitation with whole blood was associated with a 28-minute reduction in the time spent in the critical window defined by platelet count <50x109/L, INR≥2, hemoglobin <9 g/dL and fibrinogen <150 mg/dL compared with conventional component resuscitation over the course of a 4 hour simulation (p<0.001 based on median regression). We demonstrate how stochastic models of hemostatic resuscitation can be used to perform in silico trials of resuscitation strategies. Our work can guide inclusion and exclusion criteria for future clinical trials and facilitate identification of patient subgroups most likely to benefit from certain resuscitation strategies. This work was partially funded by the AABB Foundation (formerly the National Blood Foundation).

Body fluid kinetics is changed by a rise in plasma glucose

Glucose is an osmotically active molecule and, therefore, rapid changes in plasma glucose might redistribute water volume between the body fluid compartments in a yet unknown way. To study this issue, population volume kinetic analysis was applied to repeated measurements of plasma glucose, blood hemoglobin, and urine output during and after 84 intravenous infusions of 2.5 % glucose with 70 mmol of sodium and in 9 control experiments using Ringer's solution. Forty-nine infusions were given to healthy volunteers, 11 to patients undergoing surgery, and 24 to patients with type 2 diabetes. The results showed that a rise in plasma glucose without marked glucosuria accelerated the distribution of fluid while the return of extravascular fluid to the plasma was strongly retarded. High plasma glucose also decreased the urine output, which was probably due to sodium retention. The summary effect was that fluid-induced plasma volume expansion subsided within 30 min after an infusion ended while extracellular fluid volume remained increased for several hours. Accumulation of fluid was most pronounced in the patients with type 2 diabetes and in the surgical patients. Plasma glucose, HOMA-IR, and Ouicki values did not correlate with any of the kinetic parameters. In conclusion, a rise in plasma glucose conserved infused fluid in the body and promoted peripheral accumulation. A specific effect of type 2 diabetes further decreased the urine flow.

Alteration of the maximal renal water excretion capacity with kidney function and age in human.

The kidney's capability to concentrate and dilute urine is crucial to maintaining body fluid compartments and plasma osmolality. Advanced age and chronic kidney disease (CKD) result in decreased maximal urine concentration. Less is known regarding urine dilution ability. The primary purpose of this study was to determine the relationship between maximal renal water excretion and renal function, age, and gender in humans. This monocentric retrospective study includes patients referred to the Department of Clinical Physiology in Toulouse University Hospital to measure the glomerular filtration rate (mGFR) between April 2013 and February 2018. mGFR was assessed using inulin renal clearance and required ample hydration. We quantified the effects of age, gender and mGFR have on water excretion ability, which was assessed by minimal urinary osmolality (minUosm) and maximal free water clearance (maxCH2O). 666 patients were included (mean age 51 ± 14years, 53% female). Mean mGFR was 82 ± 25mL/min/1.73m2. MinUosm after hydration was higher in patients with renal insufficiency while maxCH2O was markedly lower. Age was also, with a weaker effect, associated with decreased in water excretion, independently of mGFR. MaxCH2O clearance was similar in both genders, whereas minUosm was lower in women, possibly resulting from a lower osmotic load. This study shows a decrease in maximal urinary dilution capacity and free water clearance with CKD and age, without gender difference. These alterations are mild but must be considered when a significant water intake is required or in the case of hyponatremia.

Contemporary perspectives on perioperative fluid therapy.

The primary purpose of perioperative IV fluid administration is to preserve tissue perfusion by maintaining or restoring the effective circulating intravascular volume. Fluids are drugs that produce beneficial or harmful effects dependent upon their composition, osmotic potential, kinetics, and dose. Appropriate dosing requires an understanding of body fluid compartments, fluid balance, and the administered fluids' behavior in the body. Anesthetic drugs and general anesthesia produce CNS, neuroendocrine, and macro-/microvascular hemodynamic effects. These effects modulate the response to IV fluid administration and promote interstitial fluid accumulation, third-space fluid loss, and fluid overload. This narrative review discusses current knowledge regarding anesthesia-associated physiologic and IV fluid kinetic changes that influence the efficacy of IV fluid administration during the intraoperative period. A rationale for intraoperative fluid dosing that addresses intraoperative hypotension, blood loss, and practices that promote fluid overload is provided. Intraoperative IV fluid administration should be individualized and monitored by dynamic goal-directed methods that evaluate fluid responsiveness.

Vascular refilling coefficient is not a good marker of whole-body capillary hydraulic conductivity in hemodialysis patients: insights from a simulation study

Refilling of the vascular space through absorption of interstitial fluid by micro vessels is a crucial mechanism for maintaining hemodynamic stability during hemodialysis (HD) and allowing excess fluid to be removed from body tissues. The rate of vascular refilling depends on the imbalance between the Starling forces acting across the capillary walls as well as on their hydraulic conductivity and total surface area. Various approaches have been proposed to assess the vascular refilling process during HD, including the so-called refilling coefficient (Kr) that describes the rate of vascular refilling per changes in plasma oncotic pressure, assuming that other Starling forces and the flow of lymph remain constant during HD. Several studies have shown that Kr decreases exponentially during HD, which was attributed to a dialysis-induced decrease in the whole-body capillary hydraulic conductivity (LpS). Here, we employ a lumped-parameter mathematical model of the cardiovascular system and water and solute transport between the main body fluid compartments to assess the impact of all Starling forces and the flow of lymph on vascular refilling during HD in order to explain the reasons behind the observed intradialytic decrease in Kr. We simulated several HD sessions in a virtual patient with different blood priming procedures, ultrafiltration rates, session durations, and constant or variable levels of LpS. We show that the intradialytic decrease in Kr is not associated with a possible reduction of LpS but results from the inherent assumption that plasma oncotic pressure is the only variable Starling force during HD, whereas in fact other Starling forces, in particular the oncotic pressure of the interstitial fluid, have an important impact on the transcapillary fluid exchange during HD. We conclude that Kr is not a good marker of LpS and should not be used to guide fluid removal during HD or to assess the fluid status of dialysis patients.

Ceramide-1-Phosphate as a Potential Regulator of the Second Sodium Pump from Kidney Proximal Tubules by Triggering Distinct Protein Kinase Pathways in a Hierarchic Way.

Kidney proximal tubules are a key segment in the reabsorption of solutes and water from the glomerular ultrafiltrate, an essential process for maintaining homeostasis in body fluid compartments. The abundant content of Na+ in the extracellular fluid determines its importance in the regulation of extracellular fluid volume, which is particularly important for different physiological processes including blood pressure control. Basolateral membranes of proximal tubule cells have the classic Na+ + K+-ATPase and the ouabain-insensitive, K+-insensitive, and furosemide-sensitive Na+-ATPase, which participate in the active Na+ reabsorption. Here, we show that nanomolar concentrations of ceramide-1 phosphate (C1P), a bioactive sphingolipid derived in biological membranes from different metabolic pathways, promotes a strong inhibitory effect on the Na+-ATPase activity (C1P50 ≈ 10 nM), leading to a 72% inhibition of the second sodium pump in the basolateral membranes. Ceramide-1-phosphate directly modulates protein kinase A and protein kinase C, which are known to be involved in the modulation of ion transporters including the renal Na+-ATPase. Conversely, we did not observe any effect on the Na+ + K+-ATPase even at a broad C1P concentration range. The significant effect of ceramide-1-phosphate revealed a new potent physiological and pathophysiological modulator for the Na+-ATPase, participating in the regulatory network involving glycero- and sphingolipids present in the basolateral membranes of kidney tubule cells.

Delirium in Acute Poisoning with 1,4-Butanediol and Its Correction

Delirium complicating regular use of psychoactive substances remains one of the major issues of critical care, toxicology, and psychiatry. However, the pathogenetic mechanisms of delirium development in patients with 1,4-butanediol poisoning have been poorly studied until now.The aim of the study was to reveal specific patterns of delirium in patients with 1,4-butanediol poisoning as well as to study the changes in systemic hemodynamic parameters, respiratory function, and body fluid compartments during the treatment.Material and methods. The study was prospective and treatment-randomized. Forty-eight male patients aged 20 to 45 years with delirium and acute 1,4-butanediol poisoning were enrolled. Of them, 24 patients were administered with succinate-containing drug 40 ml daily, 24 patients received standard treatment without antihypoxic agents. We studied the evolution of delirium, changes in anaerobic metabolism parameters, systemic hemodynamics, respiratory function, and the volume of fluid compartments. Impedance measurement method adjusted for interference was used in the study.Results. At the «peak» of delirium (days 1–3), the hyperdynamic circulation, increased systemic arterial tone, stroke output, respiratory function parameters, and metabolic lactate acidosis were recorded. A decrease in total fluid volume and extracellular fluid volume was clearly observed during day 1 of intoxication delirium along with increased permeability of cell membranes. On day 3 of delirium, a decrease in intracellular fluid volume and increase in extracellular fluid volume were noted. After the cytoflavin administration, shorter delirium duration (7.5 [6; 8] days), more rapid correction of lactate acidosis, stabilization of respiratory parameters and stabilization of cell membrane permeability by day 5 were found. In the control group, delirium persisted for up to 14 [11; 15] days (z=-5.9; P=0.00011) with more frequent development of complications such as nosocomial pneumonia (χ2=8.4, P<0.001).Conclusion. The severity of delirium in acute poisoning with 1,4-butanediol was associated with metabolic lactate acidosis, changes in systemic hemodynamics and pulmonary function. A positive effect of adjunctive antihypoxic therapy with succinate-containing agent on cardio-respiratory parameters, cell membrane permeability, water balance due to elimination of tissue hypoxia and prompt switching to tissue aerobic metabolism has been found.

Perturbed body fluid distribution and osmoregulation in response to high salt intake in patients with hereditary multiple exostoses

SummaryBackgroundHereditary Multiple Exostoses (HME) is a rare autosomal disorder characterized by the presence of multiple exostoses (osteochondromas) caused by a heterozygous loss of function mutation in EXT1 or EXT2; genes involved in heparan sulfate (HS) chain elongation. Considering that HS and other glycosaminoglycans play an important role in sodium and water homeostasis, we hypothesized that HME patients have perturbed whole body volume regulation and osmolality in response to high sodium conditions.MethodsWe performed a randomized cross-over study in 7 male HME patients and 12 healthy controls, matched for age, BMI, blood pressure and renal function. All subjects followed both an 8-day low sodium diet (LSD, <50 mmol/d) and high sodium diet (HSD, >200 mmol/d) in randomized order. After each diet, blood and urine samples were collected. Body fluid compartment measurements were performed by using the distribution curve of iohexol and 125I-albumin.ResultsIn HME patients, HSD resulted in significant increase of intracellular fluid volume (ICFV) (1.2 L, p = 0.01). In this group, solute-mediated water clearance was significantly lower after HSD, and no changes in interstitial fluid volume (IFV), plasma sodium, and effective osmolality were observed. In healthy controls, HSD did not influence ICFV, but expanded IFV (1.8 L, p = 0.058) and increased plasma sodium and effective osmolality.ConclusionHME patients show altered body fluid distribution and osmoregulation after HSD compared to controls. Our results might indicate reduced interstitial sodium accumulation capacity in HME, leading to ICFV increase. Therefore, this study provides additional support that HS is crucial for maintaining constancy of the internal environment.

Reproducibility of fluid status measured by bioelectrical impedance analysis in healthy volunteers: akey requirement to monitor fluid status in the intensive care unit.

Little is known about the use of bioelectrical impedance analysis (BIA) in critically ill patients. The objective of this study was to evaluate the reproducibility of BIA measurements by comparing non-dominant versus dominant body-side measurements at 2 separate time points in healthy volunteers in order to extrapolate key elements that may be of relevance in critically ill patients. Aprospective observational validation experiment was carried out in healthy volunteers. Full-body and segmental multiple frequency BIA measurements were carried out at the non-dominant and the dominant body side, consecutively, and on 2 separate occasions within 1 week. Parameters of interest were both raw data (impedance and phase angle) at the individual frequencies (5-50-100-200 kHz) and body fluid compartment volume estimations (total body water, extracellular water volume, intracellular water volume, volume excess). Atotal of 42 measurements were performed in 22 volunteers. Median (interquartile range) age and time between measurements was 26 years (24; 35) and 2.07 days (1.00; 2.99), respectively. The intraclass-correlation coefficients (ICCs) for body fluid compartment volumes estimated by full-body BIA, were greatly above 90%, showing excellent agreement, except for volume excess which showed moderate agreement. Full-body raw impedance and phase angle measurements showed highly variable and much lower ICCs. For both estimated body fluid compartment volumes and raw measurements, segmental BIA showed also highly variable and low ICCs. Overall this study showed that in healthy volunteers, BIA-derived fluid parameters are reproducible, and differences can be attributed to the changes in clinical status.

Salt and water balance after sweat loss: A study of Bikram yoga.

Bikram yoga is practiced in a room heated to 105°F with 40% humidity for 90 min. During the class a large volume of water and electrolytes are lost in the sweat, specifically, sodium is lost, the main cation of the extracellular fluid. There is little known about the volume of sweat and the amount of sodium lost in sweat during Bikram yoga or the optimum quantity of fluid required to replace these losses. The participants who took part in this small feasibility study were five females with a mean age of 47.4 ± 4.7 years and 2.6 ± 1.6 years of experience at Bikram yoga. The total body weight, water consumed, serum sodium concentration, serum osmolality, and serum aldosterone levels were all measured before and after a Bikram yoga practice. Sweat sodium chloride concentration and osmolality were measured at the end of the practice. The mean estimated sweat loss was 1.54 ± 0.65 L, while the amount of water consumed during Bikram yoga was 0.38 ± 0.22 L. Even though only 25% of the sweat loss was replenished with water intake during the Bikram yoga class, we did not observe a change in serum sodium levels or serum osmolality. The sweat contained 82 ± 16 mmol/L of sodium chloride for an estimated total of 6.8 ± 2.1 g of sodium chloride lost in the sweat. The serum aldosterone increased 3.5‐fold from before to after Bikram yoga. There was a decrease in the extracellular body fluid compartment of 9.7%. Sweat loss in Bikram yoga predominately produced a volume depletion rather than the dehydration of body fluids. The sweating‐stimulated rise in serum aldosterone levels will lead to increased sodium reabsorption from the kidney tubules and restore the extracellular fluid volume over the next 24 hr.

Methods to quantify heat stress in ruminants: Current status and future prospects.

The physiology of hyperthermia or heat stress in mammals is complex. It is a totally systemic condition that in varying degrees involves all organs, tissues and body fluid compartments. The nature and magnitude of the response is influenced by animal specific characteristics (e.g. age, diet, body condition, gender, reproductive stage), environment and animal management. Given the multifaceted nature of heat stress, and the varied ruminant production systems based in varied geoclimatic zones, it has been difficult to find appropriate measures of heat stress for production ruminants. This has become an urgent challenge as production systems intensify globally in a warming climate. Bioclimatic indices such as the Temperature-Humidity Index (THI) have evolved to incorporate some measure of animal physiology. However, these indices do not have strong relationships with core temperature trajectories and altered respiratory dynamics of animals with excessive heat load. In recent decades, the careful physiology studies of the 1950-80s, have given way to numerous studies trialling a plethora of new technologies and computational approached to measure heat stress. Infrared thermography of body surface temperatures, automated measures of respiration rate and radiotelemetry of internal body temperatures are the most intensively researched. The common goal has been to find the 'holy grail' decision-making threshold or timepoint as to the animal's wellbeing. Are we making any progress?

Hypocalcemia in sepsis: analysis of the subcellular distribution of Ca2+ in septic rats and LPS/TNF-α-treated HUVECs.

Hypocalcemia has been widely recognized in sepsis patients. However, the cause of hypocalcemia in sepsis is still not clear, and little is known about the subcellular distribution of Ca2+ in tissues during sepsis. We measured the dynamic change in Ca2+ levels in body fluid and subcellular compartments, including the cytosol, endoplasmic reticulum and mitochondria, in major organs of cecal ligation and puncture (CLP)-operated rats, as well as the subcellular Ca2+ flux in HUVECs which treated by endotoxin and cytokines. In the model of CLP-induced sepsis, the blood and urinary Ca2+ concentrations decreased rapidly, while the Ca2+ concentration in ascites fluid increased. The Ca2+ concentrations in the cytosol, ER, and mitochondria were elevated nearly synchronously in major organs in our sepsis model. Moreover, the calcium overload in CLP-operated rats treated with calcium supplementation was more severe than that in the non-calcium-supplemented rats but was alleviated by treatment with the calcium channel blocker verapamil. Similar subcellular Ca2+ flux was found in vitro in HUVECs and was triggered by lipopolysaccharide (LPS)/TNF-α. Ca2+ influx from the blood into the intercellular space and Ca2+ release into ascites fluid may cause hypocalcemia in sepsis and that this process may be due to the synergistic effect of endotoxin and cytokines.

Prognostic value of lung ultrasonography and bioimpedance spectroscopy in patients with heart failure and reduced ejection fraction.

Chronic heart failure (HF) represents a major global public health problem, and despite significant advances in diagnosis and management over the past two decades, HF patients still have a poor prognosis. The aim of the study was to evaluate the relationship between lung congestion, as assessed by lung ultrasonography (LUS), bioimpedance spectroscopy, body fluid compartments, and echocardiographic parameters, and to determine the effect of these associations on all-cause mortality in HF patients. Eligible patients with a left ventricular ejection fraction (LVEF) below 45% were identified via daily echocardiography assessments. Lung ultrasonography was performed with patients in the supine position, for a total of 28 sites per complete examination. The extracellular water (ECW) was determined using a BIS device. Our study included 122 patients (67.2% males) with a mean age of 67.2 years. In the multivariable linear regression analysis, including all the univariable predictors of lung congestion, only New York Heart Association (NYHA) class, ECW, estimated glomerular filtration rate (eGFR), and LVEF levels maintained an independent association with the number of B-lines. During the follow-up, 33 patients died. In multivariable Cox analysis, a B-line number of at least 15 remained significantly associated with all-cause mortality, independently of age, sex, diabetes, LVEF, estimated glomerular filtration rate, C-reactive protein, N-terminal pro-brain natriuretic peptide, or ECW values (adjusted HR = 3.84, 95% CI: 1.12-13.09). We show for the first time in HF patients that pulmonary congestion, as assessed by LUS, is associated with the severity of NYHA class, LVEF, eGFR, and ECW, and it identifies those at increased risk of death.

Perioperative fluid dynamics evaluated by bioelectrical impedance analysis predict infectious surgical complications after esophagectomy

BackgroundTransthoracic esophagectomy, among the most invasive surgeries, is highly associated with postoperative infectious complications which adversely affect postoperative management including fluid dynamics. The aim of the study is to evaluate the utility of perioperative bioelectrical impedance analysis (BIA) measurements for the patients after transthoracic esophagectomy.MethodMulti-frequency BIA measurements were conducted in 24 patients undergoing transthoracic esophagectomy preoperatively, at 1 h after surgery, and twice daily for the following 7 days. The amounts of extracellular water (ECW), internal cellular water (ICW), total body water (TBW), and fat-free mass (FFM) were calculated. Changing trends in variables were analyzed, and the patients were subdivided according to the presence of infectious surgical adverse events to identify differences in fluid dynamics.ResultsECW was the major body fluid compartment showing an increase after surgery, and peaked on postoperative day (POD) 2. Twelve patients experienced infectious complications. The peaks of changes in ECW and ECW/TBW appeared earlier and their values at the highest peak were significantly lower in the group without infectious complications on POD 2. The ICW/FFM value showed a mild decrease as compared to POD1 and then gradually recovered. It was significantly lower even before surgery and showed the most significant stratification on POD2. ECW/TBW of 48% and ICW/FFM of 37% on POD2 were predictive cut-off values for infectious adverse events with high area-under receiver operating characteristic (ROC) curves: 0.80 or higher.ConclusionBIA measurements are useful for monitoring fluid retention and may predict infectious complications in the early phase after transthoracic esophagectomy.Trial registrationRegistry name: UMIN-CTR, ID: UMIN000030734, Registered on January 9, 2018, retrospectively registered.

Providing fluid therapy to equine colic patients. Part 1

Background: Fluid therapy is a life-saving measure, which is fundamental in managing horses with colic. It is essential for the clinician to be familiar with the available options when devising...

Multi-System Adaptation to Confinement During the 180-Day Controlled Ecological Life Support System (CELSS) Experiment.

Confinement experiments are essential to prepare long-term space exploration. The 180-day Chinese CELSS (Controlled Ecological Life Support System) study is unique in its design, including a closed-loop system and mid-mission simulation of Mars-like day–night cycle of 24 h 40 min for 36 days (days 72–108). Our aim was to study physiological and psychological consequences of this confinement in four healthy volunteers (one female). CELSS platform consisted of six interconnected modules including four greenhouses. Life support systems were controlled automatically. Body composition, fluid compartments, metabolic state, heart, large vessels, endothelial function, and muscle tone were studied using biological, functional, and/or morphological measurements. Behavioral activities were studied by ethological monitoring; psychological state was assessed by questionnaires. Body weight decreased by ∼2 kg mostly due to lean mass loss. Plasma volume and volume-regulating hormones were mostly stable. Carotid intima-media thickness (IMT) increased by 10–15%. Endothelium-dependent vasodilation decreased. Masseter tone increased by 6–14% suggesting stress, whereas paravertebral muscle tone diminished by 10 ± 6%. Behavioral flow reflecting global activity decreased 1.5- to 2-fold after the first month. Psychological questionnaires revealed decrease in hostility and negative emotions but increase in emotional adaptation suggesting boredom and monotony. One subject was clearly different with lower fitness, higher levels of stress and anxiety, and somatic signs as back pain, peak in masseter tone, increased blood cortisol and C-reactive protein. Comparison of CELSS experiment with Mars500 confinement program suggests the need for countermeasures to prevent increased IMT and endothelial deconditioning. Daily activity in greenhouse could act as countermeasure against psycho-physiological deconditioning.

Uraemic syndrome of chronic kidney disease: altered remote sensing and signalling.

Uraemic syndrome (also known as uremic syndrome) in patients with advanced chronic kidney disease involves the accumulation in plasma of small-molecule uraemic solutes and uraemic toxins (also known as uremic toxins), dysfunction of multiple organs and dysbiosis of the gut microbiota. As such, uraemic syndrome can be viewed as a disease of perturbed inter-organ and inter-organism (host-microbiota) communication. Multiple biological pathways are affected, including those controlled by solute carrier (SLC) and ATP-binding cassette (ABC) transporters and drug-metabolizing enzymes, many of which are also involved in drug absorption, distribution, metabolism and elimination (ADME). The remote sensing and signalling hypothesis identifies SLC and ABC transporter-mediated communication between organs and/or between the host and gut microbiota as key to the homeostasis of metabolites, antioxidants, signalling molecules, microbiota-derived products and dietary components in body tissues and fluid compartments. Thus, this hypothesis provides a useful perspective on the pathobiology of uraemic syndrome. Pathways considered central to drug ADME might be particularly important for the body's attempts to restore homeostasis, including the correction of disturbances due to kidney injury and the accumulation of uraemic solutes and toxins. This Review discusses how the remote sensing and signalling hypothesis helps to provide a systems-level understanding of aspects of uraemia that could lead to novel approaches to its treatment.

Learning (by) osmosis: an approach to teaching osmolarity and tonicity.

Understanding osmolarity and tonicity is one of the more challenging endeavors undertaken by students of the natural sciences. We asked students who completed a course in animal physiology to submit an essay explaining what they found most perplexing about this subject, and what in-class activities proved most useful to them. Students had difficulty distinguishing osmolarity from tonicity and determining tonicity based on the solution's composition. The most useful activities were questions requiring simultaneous consideration of both osmolarity and tonicity. Problems that require calculating osmotic concentration and the volumes of body fluid compartments after administration or loss of various solutions emphasize the significance of osmolarity and tonicity in the context of systemic homeostasis and clinical medicine. We hope that our approach to teaching osmolarity and tonicity will prove useful to physiology lecturers who are looking for new ways of introducing this complicated topic to their health professions students.