Physiology of body fluids

2016 ◽  
Author(s):  
Anthony Delaney
Keyword(s):  
Interstitial Fluid ◽  
Extracellular Volume ◽  
Extracellular Fluid ◽  
Body Fluids ◽  
The Body ◽  
Fluid Replacement ◽  
Fluid Status ◽  
Healthy Humans ◽  
Fluid Compartment ◽  
The Difference

An understanding of the physiology of body fluids is essential when considering appropriate fluid resuscitation and fluid replacement therapy in critically-ill patients. In healthy humans, the body is composed of approximately 60% water, distributed between intracellular and an extracellular compartments. The extracellular compartment is divided into intravascular, interstitial and transcellular compartments. The movement of fluids between the intravascular and interstitial compartments, is classically described as being governed by Starling forces, leading to a small net efflux of fluid from the intravascular to the interstitial compartment. More recent evidence suggests that a model incorporating the effect of the endothelial glycoclayx layer, a web of glycoproteins and proteoglycans that are bound on the luminal side of the vascular endothelium, better explains the observed distribution of fluids. The movement of fluid to and from the intracellular compartment and the interstitial fluid compartment, is governed by the relative osmolarities of the two compartments. Body fluid status is governed by the difference between fluid inputs and outputs; fluid input is regulated by the thirst mechanism, with fluid outputs consisting of gastrointestinal, renal, and insensible losses. The regulation of intracellular fluid status is largely governed by the regulation of the interstitial fluid osmolarity, which is regulated by the secretion of antidiuretic hormone from the posterior pituitary gland. The regulation of extracellular volume status is regulated by a complex neuro-endocrine mechanism, designed to regulate sodium in the extracellular fluid.

Extracellular and intracellular carbon dioxide concentration as a function of temperature in the toad Bufo marinus.

1994 ◽  
Vol 195 (1) ◽  
pp. 345-360 ◽  
Author(s):  
J N Stinner ◽  
D L Newlon ◽  
N Heisler
Keyword(s):  
Body Temperature ◽  
Extracellular Fluid ◽  
Carbon Dioxide Concentration ◽  
The Body ◽  
Whole Body ◽  
Mean Values ◽  
Temperature Changes ◽  
Fluid Compartment ◽  
Average Change ◽  
Higher Temperature

Previous studies of reptiles and amphibians have shown that changing the body temperature consistently produces transient changes in the respiratory exchange ratio (RE) and, hence, changes in whole-body CO2 stores, and that the extracellular fluid compartment contributes to the temperature-related changes in CO2 stores. The purpose of this study was to determine whether the intracellular fluid compartment contributes to the changes in CO2 stores in undisturbed resting cane toads. Increasing body temperature from 10 to 30 degrees C temporarily elevated RE, and returning body temperature to 10 degrees C temporarily lowered RE. The estimated average change in whole-body CO2 stores associated with the transient changes in RE was 1.0 +/- 0.8 mmol kg-1 (+/- S.D., N = 6). Plasma [CO2] and, thus, extracellular fluid [CO2], were unaffected by the temperature change. Plasma calcium levels were also unaffected, so that bone CO2 stores did not contribute to changes in whole-body CO2 stores. Intracellular [CO2] was determined for the lung, oesophagus, stomach, small intestine, liver, ventricle, red blood cells, skin and 14 skeletal muscles. [CO2] was significantly lower (P < 0.05) at higher temperature in 10 of these, and seven others, although not statistically significant (P > 0.05), had mean values at least 0.5 mmol kg-1 lower at the higher temperature. The average change in intracellular [CO2] for all tissues examined was -0.165 mmol kg-1 degrees C-1. We conclude that, in cane toads, the temperature-related transients in RE result from intracellular CO2 adjustments, that different tissues have unique intracellular CO2/temperature relationships, and that a combination of respiratory and ion-exchange mechanisms is used to adjust pH as temperature changes.

CO2 balance of a heterothermic rodent: comparison of sleep, torpor, and awake states

1984 ◽  
Vol 246 (1) ◽  
pp. R49-R55 ◽  
Author(s):  
P. E. Bickler
Keyword(s):  
Ground Squirrel ◽  
Lung Ventilation ◽  
Body Fluids ◽  
The Body ◽  
Metabolic Intensity ◽  
Co2 Balance ◽  
The Difference ◽  
Tb 32 ◽  
Total Body ◽  
Thermal States

CO2 homeostasis of different thermal states have been compared in a heterothermic ground squirrel, Spermophilus tereticaudus. Gas exchange (MO2, MCO2), lung ventilation (VE), and body temperature (Tb) were simultaneously measured during sleep, shallow torpor (Tb 25-29 degrees C), deep torpor (Tb 11-15 degrees C), awake heterothermia (Tb 30-42.5 degrees C), and transitions between these states. CO2 retention (falling MCO2/MO2 and VE/MCO2) accompanied entrance into sleep and torpor. CO2 retention lowered MO2 in sleeping and torpid squirrels beyond that caused by reduced Tb. In torpor at steady state, MCO2/MO2 (R) and ventilation returned to control values, and no further CO2 retention occurred. Arousal from sleep or torpor was accompanied by transiently high VE/MCO2 and R values as CO2 was released from the body fluids. R and VE/MCO2 values during heterothermia in awake squirrels (Tb 32-42.5 degrees C) showed that total body CO2 content remained unchanged until Tb reached 40 degrees C with onset of hyperventilation. Altered CO2 content of the body fluids is thus not a general feature of mammalian heterothermy. The difference in CO2 homeostasis of torpid and heterothermic awake animals may have implications for the difference in metabolic intensity of these states.

Relationship between interstitial fluid volume and pressure (compliance) in hypothyroid rats

2001 ◽  
Vol 281 (3) ◽  
pp. H1085-H1092 ◽  
Author(s):  
Helge Wiig ◽  
Tjøstolv Lund
Keyword(s):  
Skeletal Muscle ◽  
Peritoneal Dialysis ◽  
Thyroid Hormones ◽  
Interstitial Fluid ◽  
Experimental Situation ◽  
Fluid Pressure ◽  
Extracellular Fluid ◽  
Fluid Volume ◽  
The Body ◽  
Interstitial Fluid Volume

There is clinical and experimental evidence that lack of thyroid hormones may affect the composition and structure of the interstitium. This can influence the relationship between volume and pressure during changes in hydration. Hypothyrosis was induced in rats by thyroidectomy 8 wk before the experiments. Overhydration was induced by infusion of acetated Ringer, 5, 10, and 20% of the body weight, while fluid was withdrawn by peritoneal dialysis with hypertonic glucose. Interstitial fluid pressure (Pi) in euvolemia (euvolemic control situation) and experimental situation was measured with micropipettes connected to a servocontrolled counterpressure system. The corresponding interstitial fluid volume (Vi) was found as the difference between extracellular fluid volume measured as the distribution volume of 51Cr-labeled EDTA and plasma volume measured using125I-labeled human serum albumin. In euvolemia, Vi was similar or lower in the skin and higher in skeletal muscle of hypothyroid than in euthyroid control rats, whereas the corresponding Pi was higher in all tissues. During overhydration, Pi rose to the same absolute level in both types of rats, whereas during peritoneal dialysis there was a linear relationship between volume and pressure in all tissues and types of rats. Interstitial compliance (Ci), calculated as the inverse value of the slope of the curve relating changes in volume and pressure in dehydration, did not differ significantly in the hindlimb skin of hypothyroid and euthyroid rats. However, in skeletal muscle, Ci was 1.3 and 2.0 ml · 100 g−1 · mmHg−1 in hypothyroid and euthyroid rats ( P < 0.01), with corresponding numbers for the back skin of 2.7 and 5.0 ml · 100 g−1 · mmHg−1 ( P < 0.01). These experiments suggest that lack of thyroid hormones in rats changes the interstitial matrix, again leading to reduced Ci and reduced ability to mobilize fluid from the interstitium.

scholarly journals Body Fluids in End-Stage Renal Disease: Statics and Dynamics

2018 ◽  
Vol 47 (1-3) ◽  
pp. 223-229 ◽  
Author(s):  
Jeroen P. Kooman ◽  
Frank M. van der Sande
Keyword(s):  
Cardiovascular Response ◽  
Extracellular Volume ◽  
Extracellular Fluid ◽  
Central Venous Oxygen Saturation ◽  
Tissue Perfusion ◽  
Adverse Outcomes ◽  
Fluid Distribution ◽  
Fluid Removal ◽  
Fluid Status ◽  
Statics And Dynamics

Background: Abnormalities in fluid status in hemodialysis (HD) patients are highly prevalent and are related to adverse outcomes. Summary: The inherent discontinuity of the HD procedure in combination with an often compromised cardiovascular response is a major contributor to this phenomenon. In addition, systemic inflammation and endothelial dysfunction are related to extracellular fluid overload (FO). Underlying this relation may be factors such as hypoalbuminemia and an increased capillary permeability, leading to an altered fluid distribution between the blood volume (BV) and the interstitial fluid compartments, compromising fluid removal during dialysis. Indeed, whereas estimates of extracellular volume by bioimpedance spectroscopy are highly predictive of mortality, absolute BV assessed by the saline dilution technique was predictive of intra-dialytic morbidity. Changes in relative BV during HD are positively related to ultrafiltration rate (UFR) and, at least in some studies, negatively to FO. High UFR is also related to changes in central venous oxygen saturation (ScvO2), a marker for tissue perfusion. On the one hand, high UFR and more pronounced declines in ScvO2, but on the other hand, flat relative BV curves are also predictive of mortality; the relation between outcome which statics and dynamics of fluid status appears to be complex. Key Message: While technological developments enable the clinician to monitor statics and dynamics of fluid status and hemodynamics during HD in an accessible way, the role of technology-based interventions needs further study.

scholarly journals Characteristics of Intracellular and Extracellular Fluid Ratio for the Varying Body Impedances in Fixed Total Body Fluid

2017 ◽  
Author(s):  
JungHun Choi
Keyword(s):  
Human Body ◽  
High Frequency ◽  
Body Fluid ◽  
Extracellular Fluid ◽  
Bioelectrical Impedance ◽  
The Body ◽  
Horizontal Axis ◽  
Fluid Status ◽  
Total Body ◽  
Frequency Current

A bioelectrical impedance analysis is a proven method to measure body composition in clinical situations. It uses the relation between the body fluid and the impedances in a variety of frequencies. A body model can be simplified as a parallel combination of a capacitor and two resistors which represent a cell membrane, Intracellular Fluid (ICF), and Extracellular Fluid (ECF). Low frequency current passes through ECF and high frequency current also passes through ICF in a body. A Cole-Cole plot is a graphical interpretation of the path of impedances and each axis represents resistance and reactance with variable frequencies. A high value of resistance in a horizontal axis is a resistance value of ECF and a low value of resistance at a high frequency presents ICF. Interpolation technique is needed to find out the exact cross-point between impedance values and the horizontal axis. The two estimated impedance values are used to derive Total Body Water (TBW), ICF, ECF, Fat Free Mass (FFM), and Fat Mass (FM) from various published equations [1]. Minimizing the possible error of fluid volume assessment and accurate prediction of fluid status in a human body is essential for appropriate therapy. Different techniques of fluid status assessment in a human body can be applicable, such as physical examination, orthostatic vital signs, blood volume measurement, acoustic cardiograph, chest radiography, and thoracic ultrasonography [2]. In this study, a bioelectrical impedance spectroscopy device and simple body models were used to collect data such as TBW, ICF, ECF, FM, and FFM. The ratio between ICF and ECF was investigated for the same values of TBW, FM, and FFM by varying impedance values.

Effect of Canagliflozin on Estimated Fluid Volumes in Patients with Heart Failure and type 2 Diabetes: A Post-hoc Analysis of the CANDLE Trial

2021 ◽  
Author(s):  
Shinya Fujiki ◽  
Takumi Imai ◽  
Atsushi Tanaka ◽  
Michio Shimabukuro ◽  
Hiroki Uehara ◽  
...  
Keyword(s):  
Heart Failure ◽  
Type 2 Diabetes ◽  
Extracellular Volume ◽  
Sglt2 Inhibitor ◽  
The Body ◽  
Open Label ◽  
Post Hoc Analysis ◽  
The Difference ◽  
Post Hoc

Abstract Background:In patients with chronic heart failure (CHF) and type 2 diabetes (T2D), inhibition of the sodium-glucose cotransporter-2 (SGLT2) improves cardiorenal outcomes, but the effects of the SGLT2 inhibitor canagliflozin on body fluid volume and renal function remain to be clarified.Methods:This was a post-hoc analysis of 233 patients with CHF and T2D in the CANDLE Trial (UMIN000017669), an investigator-initiated, multi-center, randomized open-label trial that compared the effect of canagliflozin (100 mg, n=113) with glimepiride (starting dose: 0.5 mg, n=120) on changes in N-terminal pro-brain natriuretic peptide. The time courses of estimated plasma volume (ePV, calculated with the Straus formula), estimated extracellular volume (eEV, determined by the body surface area), and estimated glomerular filtration rate (eGFR, calculated with the modified Cockcroft formula) were compared between the canagliflozin and glimepiride groups at weeks 4, 12, and 24. Results:Reductions in ePV and eEV were observed only in the canagliflozin group until week 12 (change from baseline at week 12, ePV; -7.63%; 95% confidence interval [CI], -10.71 to -4.55%, p<0.001, eEV; -123.15 mL; 95% CI, -190.38 to -55.92 mL, p<0.001). Whilst ePV stopped falling after week 12, eEV continued to fall until week 24 ([change from baseline at week 24] – [change from baseline at week 12], ePV; 1.01%; 95%CI, -2.30 to 4.32%, p=0549, eEV; -125.15 mL; 95% CI, -184.35 to -65.95 mL, p<0.001). An initial significant reduction in eGFR was observed in the canagliflozin group (change from baseline at week 4, -4.18 mL/min/1.73 m2; 95% CI, -5.99 to -2.37 mL/min/1.73 m2, p<0.001), but after 4 weeks, eGFR stopped falling, and the difference between groups became insignificant (change from baseline at week 24, -1.27 mL/min/1.73 m2; 95% CI, -3.05 to 0.51 mL/min/1.73 m2, p=0.162, [change from baseline at week 24] – [change from baseline at week 12], 0.89 mL/min/1.73 m2; 95% CI, -0.74 to 2.51 mL/min/1.73 m2, p=0.284).Conclusions:Canagliflozin reduced ePV and eEV gradually, whilst glimepiride did not. Maintenance of a modest reduction in ePV by canagliflozin suggests appropriate intravascular volume reduction contributing to cardiorenal benefits in patients with CHF and T2D.Trial Registration: UMIN000017669

scholarly journals P0612UTILITY OF BODY COMPOSITION MONITORING (BCM) TO CORRELATE FLUID STATUS AND AKI IN PATIENTS UNDERGOING MAJOR CARDIAC SURGERY AND OUTCOMES

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Rajeevalochana Parthasarathy ◽  
Madhusri Babu ◽  
Merina Alex ◽  
Preethi Nagesh ◽  
Milly Mathew ◽  
...  
Keyword(s):  
Acute Kidney Injury ◽  
Body Composition ◽  
Cardiac Surgery ◽  
Informed Consent ◽  
Fluid Overload ◽  
Statistical Significance ◽  
Extracellular Volume ◽  
Kidney Injury ◽  
The Body ◽  
Fluid Status

Abstract Background and Aims Technically assisted assessment of volume status before cardiac surgery may be useful to direct intraoperative fluid administration. Using a three-compartment physiologic tissue model, the body composition monitor (BCM, In Body) measures total body fluid volume, extracellular volume, intracellular volume and fluid overload as surplus or deficit of ‘normal’ extracellular volume. Fluid overload is a risk factor for infection, increased re intubation rates, pneumonia and acute kidney injury in these high risk patients. This study is planned to use BCM to assess fluid status in patients undergoing cardiac surgery and correlating it with the risk of AKI AIMS: To do BCM analysis of patients undergoing major cardiac surgery to assess fluid status and renal outcomes Primary Objective To use BCM to assess fluid status in patients undergoing cardiac surgery and correlate it with the risk of acute kidney injury Secondary Objectives To assess the correlation of fluid status obtained by BCM to assess 1. In hospital mortality in patients with and without AKI Method The studyis being conducted at Madras Medical Mission, Chennai. Time period : 1 year ( June 1 2019- May 31 2020) Inclusion criteria All consecutive patients above 18 years of age undergoing cardiac surgery Exclusion criteria 1. No informed consent 2. Patients having metal implants, pace makers 3. Pregnant and lactating mothers After informed consent, all adult patients undergoing cardiac surgery will have a BCM analysis done by the dietician .( Free of Charge) The BCM analysisInbody S10) will be done on Day 0( preoperative), Day 2 and Day 5 . Data will be collected according to a set proforma ( Attached) . Analysis will be performed using the SPSS platform. Results In this pilot study, 134 patients who underwent major cardiac surgery were enrolled. Of these 44 patients developed AKI as defined by KDIGO criteria( 22 Stage 1, 15 stage 2, and 7 stage 3). There was no statistical significance in the baseline characteristics when compared to age, gender, htn, ckd between patients with and without aki. Overhydration as measured by ECW/TBW ration of &gt; 0.38 was significantly higher on day 2 and 5 in patients who developed AKI .(P&lt;0.00, All 44 patients in aki versus 40 in the non aki group). The PBF, ICW, BMI nad overall BCM score was higher in patient with AKI ( p&lt;0.00). 7 patients required RRT( 6 SLED and 1 Acute PD). There was 1 death in theAKI group. The mean duration of hospital stay was longer ( 14 +/- 5 vs 7 +/- 3.5 ) in the AKI grroup Conclusion There is not much data on BCM and fluid assessment in cardiac surgery patients. These patients have many risk factors and a failing heart and associated renal dysfunction in many makes it very difficult to guide volume therapy in these patients. Many of the so called standard objective measures in assessing volume are not fool- proof . This study will be one of the firsts from India to assess fluid status in these patients and help in guiding therapy and also knowing the outcomes of such an objective measurement

BACK TO BASICS

1996 ◽  
Vol 17 (11) ◽  
pp. 395-403
Author(s):  
Nicholas Jospe ◽  
Gilbert Forbes
Keyword(s):  
Total Body Water ◽  
Extracellular Fluid ◽  
Body Fluids ◽  
Body Water ◽  
The Body ◽  
Electrolyte Balance ◽  
Electrolyte Disorders ◽  
Core Concepts ◽  
Body Fluid Volume ◽  
Total Body

Changes in volume and composition of body fluids due to disorders of fluid and electrolyte balance cause various common clinical illnesses. The rationale for reviewing the diagnosis and management of fluid and electrolyte disorders was eloquently denoted by Dr Altemeier, when he suggested that this knowledge belongs among the core concepts needed by the "keepers of the gates," that is, primary care pediatricians.1 In the body, homeostasis is maintained by the coordinated action of behavioral, hormonal, renal, and vascular adaptations to volume and osmotic changes. These core issues have been outlined in a previous article in this journal by Dr Hellerstein, and the current article proceeds from that discussion.2 Following introductory comments about body fluid volume and composition, we provide an overview of some of the etiologies of the disorders of volume, tonicity, and composition of body fluids and of the therapy to correct these disorders. Sodium, Osmolality, and the Volume of Body Fluids Total body water, which is 55% to 72% of body mass, varies with sex, age, and fat content and is distributed between the intracellular and extracellular spaces. The extracellular fluid (ECF), which comprises about one third of total body water, includes the intravascular plasma fluid and the extravascular interstitial fluid.

MO662EFFECT OF ARTERIOVENOUS VASCULAR ACCESS ON BIOIMPEDANCE MEASUREMENTS IN HEMODIALYSIS PATIENTS

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Lin-Chun Wang ◽  
Fansan Zhu ◽  
Ohnmar Thwin ◽  
Priscila Preciado Rojas ◽  
Laura Rosales Merlo ◽  
...  
Keyword(s):  
Statistical Significance ◽  
Objective Assessment ◽  
Fluid Management ◽  
The Body ◽  
Whole Body ◽  
Large Contribution ◽  
Fluid Status ◽  
Single Side ◽  
The Difference ◽  
The Impact

Abstract Background and Aims Fluid management remains a major problem in hemodialysis (HD) patients, partly because of the lack of objective assessment methods. Many methods have been proposed to estimate the fluid status in HD patients and bioimpedance has established as one of the most popular clinical tools. Resistance to alternate current was found to be lower in the arteriovenous (AV) access-bearing side compared with the non-access side in post-HD bioimpedance measurements. We hypothesized this difference between access and non-access sides can be seen in both pre- and post-HD measurements of arms and whole body. The aim of the study was to investigate whether this variation between access and non-access sides could affect single-side whole body measurements. Method Pre- and post-HD bioimpedance measurements with two 8-point devices (InBody 770 and Seca mBCA 514) were performed in 11 HD patients with functioning AV access in the arm (8 male, pre-HD 75.4 ± 13.6 kg, post-HD 72.8 ± 13.5 kg). Values of resistance at 5 kHz (R5) in the arm and whole body (R5 of arm + trunk + leg on the same side) were extracted. Whole-body extracellular water (ECW) was calculated using whole-body R5 by the Xitron equation* to evaluate how measuring only one side of the body can affect the fluid volume calculation. Results The R5 of the arm on the access side was lower compared with the non-access side both pre- and post-HD (P &lt; 0.01), measured by InBody. The same was seen with the Seca but did not reach statistical significance (Table 1). The estimated whole-body ECW was higher on the access side for InBody (P &lt; 0.01). With Seca, the same trend was seen but remained non-significant. While the difference in ECW between both arms reported by InBody was small, the impact on calculated whole-body ECW was much larger with a difference between sides of 0.50 ± 0.82 L pre HD and 0.55 ± 0.81 L post HD. Conclusion InBody appears to pick up the difference in fluid status between the access and non-access side with greater precision than Seca. The large contribution of the arm to whole-body resistance amplifies the impact of the presence of an AV access on whole-body ECW estimations based on single-side wrist-to-ankle bioimpedance measurements. Eight-point bioimpedance devices (like the tested InBody and Seca) measure both sides of the body, so, choice of measurement side does not enter the picture.

Fluid and electrolyte physiology in anaesthetic practice

2017 ◽  
Author(s):  
Robert G. Hahn
Keyword(s):  
Blood Volume ◽  
Body Fluid ◽  
Extracellular Fluid ◽  
Haemorrhagic Shock ◽  
The Body ◽  
Intracellular Space ◽  
Fluid Compartment ◽  
Life Saving ◽  
Total Body ◽  
Infusion Fluid

The maintenance of body fluid homeostasis is an essential task in perioperative care. Body fluid volumes are tightly controlled by the nervous system, by hormones, and by the kidneys. All these systems are affected by anaesthesia and surgery in ways that must be appreciated by the anaesthetist. Administration of infusion fluids is the key tool to prevent major derangements of the body fluid volumes during before, during, and after surgery. By varying its composition, an infusion fluid can be made to selectively expand or shrink a body fluid compartment. The total osmolality determines whether the infused volume distributes over the total body water or over the extracellular fluid volume, or even attracts fluid from intracellular space. Infusion fluid is the first-line tool in the management of the vasodilation that is induced by both general and regional anaesthesia. Fluids are also an essential component in the treatment of haemorrhage, in which a reduction in arterial pressure implies that 20% of the blood volume has been lost. Capillary refill restores the blood volume, but too slowly to prevent haemorrhagic shock. In this situation, prompt intravenous fluid therapy is life-saving. Electrolyte derangements may be induced by disease and/or medication. The most essential ones to consider during anaesthesia are sodium, potassium, calcium, and bicarbonate.

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