Detection of dehydration by using volume kinetics

The Volume-Cost Relationship: How Does Surgical Volume Affect Cost and Value in AIS Surgery

STUDY DESIGN

Retrospective review.

OBJECTIVE

The objective of this study was to evaluate and compare distribution of hospital and operating room charges and outcomes during posterior spinal fusion for adolescent idiopathic scoliosis (AIS) patients by high-volume (HV) and standard-volume (SV) surgeons at one institution and examine potential cost savings.

SUMMARY OF BACKGROUND DATA

Increased surgical volume has been associated with improved perioperative outcomes after spinal deformity correction. However, there is a lack of information on how this may affect hospital costs.

METHODS

Retrospective study of AIS patients undergoing posterior spinal fusion between 2013 and 2019. Demographic, x-ray, chart review and hospital costs were collected and compared between HV surgeons (≥50 AIS cases/y) and SV surgeons (<50/y). Comparative analyses were computed using Wilcoxon rank-sum, Kruskal-Wallis, and the Fisher exact tests. Average values with corresponding minimum-maximum rages were reported.

RESULTS

A total of 407 patients (HV: 232, SV: 175) operated by 4 surgeons (1 HV, 3 SV). Radiographic parameters were similar between the groups. HV surgeons had significantly lower estimated blood loss (385.3 vs. 655.6 mL, P <0.001), fewer intraoperative transfusions (10.8% vs. 25.1%, P <0.001), shorter surgery time (221.6 vs. 324.9 min, P <0.001), and lower radiation from intraoperative fluoroscopy (4.4 vs. 6.4 mGy, P <0.001). HV patients had a significantly lower length of stay (4.3 vs. 5.3, P <0.001) and complication rate (0.4% vs. 4%, P =0.04).HV surgeons had significantly lower total costs ($61,716.24 vs. $72,745.93, P <0.001). This included lower transfusion costs ( P <0.001), operative time costs ( P <0.001), screw costs ( P <0.001), hospital stay costs ( P <0.001), and costs associated with 30-day emergency department returns ( P <0.001).

CONCLUSION

HV surgeons had significantly lower operative times, lower estimated blood loss and transfusion rates and lower perioperative complications requiring readmission or return to emergency department resulting in lower health care costs.

LEVEL OF EVIDENCE

Level III.

Can perioperative hemodilution be monitored with non-invasive measurement of blood hemoglobin?

BACKGROUND

Trends in non-invasive measurements of blood hemoglobin (Hb) may be useful for identifying the need for transfusion in the perioperative period.

METHODS

Crystalloid fluid (5-20 mL/kg) was administered intravenously or by mouth to 30 volunteers and 33 surgical patients in five non-randomized clinical studies where Hb was measured on 915 occasions by non-invasive (Radical-7™) and invasive methodology. The hemodilution curves were compared by volume kinetic analysis and linear regression, with the slope and scattering of the data as key outcome measures.

RESULTS

The slope was 1.0, indicating unity between the two modes of measuring Hb when crystalloid fluid was infused in volunteers; however, only 40-45% of the variability in the non-invasive Hb could be explained by the invasive Hb. Patients undergoing major surgery, who showed the most pronounced hemodilution (median 24 g/L); non-invasive Hb explained 72% of the variability but indicated only half the magnitude of the invasive Hb changes (slope 0.48, P < 0.001 versus the volunteers). Simulations based on volume kinetic parameters from the volunteers showed 25% less plasma volume expansion after infusion when based on non-invasive as compared to invasive Hb, while no difference was found during infusion.

CONCLUSIONS

In volunteers the non-invasive Hb had good accuracy (low bias) but poor precision. In surgical patients the non-invasive Hb had good precision but systematically underestimated the hemodilution. Despite severe limitations, the non-invasive technology can be used to follow Hb trends during surgery if supported by occasional invasive measurements to assure acceptable quality of the hemodilution curve.

TRIAL REGISTRATIONS

ControlledTrials.gov NCT01195025, NCT01062776, NCT01458678, NCT03848507, and NCT01360333 on September 3, 2010, February 4, 2010, October 25, 2011, February 20, 2019, and May 25, 2011, respectively.

Understanding Volume Kinetics: The Role of Pharmacokinetic Modeling and Analysis in Fluid Therapy

Fluid therapy is a rapidly evolving yet imprecise clinical practice based upon broad assumptions, species-to-species extrapolations, obsolete experimental evidence, and individual preferences. Although widely recognized as a mainstay therapy in human and veterinary medicine, fluid therapy is not always benign and can cause significant harm through fluid overload, which increases patient morbidity and mortality. As with other pharmaceutical substances, fluids exert physiological effects when introduced into the body and therefore should be considered as "drugs." In human medicine, an innovative adaptation of pharmacokinetic analysis for intravenous fluids known as volume kinetics using serial hemoglobin dilution and urine output has been developed, refined, and investigated extensively for over two decades. Intravenous fluids can now be studied like pharmaceutical drugs, leading to improved understanding of their distribution, elimination, volume effect, efficacy, and half-life (duration of effect) under various physiologic conditions, making evidence-based approaches to fluid therapy possible. This review article introduces the basic concepts of volume kinetics, its current use in human and animal research, as well as its potential and limitations as a research tool for fluid therapy research in veterinary medicine. With limited evidence to support our current fluid administration practices in veterinary medicine, a greater understanding of volume kinetics and body water physiology in veterinary species would ideally provide some evidence-based support for safer and more effective intravenous fluid prescriptions in veterinary patients.

Evaluation of the Distribution and Elimination of Balanced Isotonic Crystalloid, 5% Hypertonic Saline, and 6% Tetrastarch 130/0.4 Using Volume Kinetic Modeling and Analysis in Healthy Conscious Cats

This prospective, randomized, blinded, interventional cross-over study investigated the distribution, elimination, plasma volume expansion, half-life, comparative potency, and ideal fluid prescription of three commonly prescribed intravenous (IV) fluids in 10 healthy conscious cats using volume kinetic analysis that is novel to veterinary medicine. Each cat received 20 mL/kg of balanced isotonic crystalloid (PLA), 3.3 mL/kg of 5% hypertonic saline (HS), and 5 mL/kg of 6% tetrastarch 130/0.4 (HES) over 15 min on separate occasions. Hemoglobin concentration, red blood cell count, hematocrit, heart rate, and blood pressure were measured at baseline, 5, 10, 15, 20, 30, 40, 50, 60, and every 15 min until 180 min. Urine output was estimated every 30 min using point-of-care bladder ultrasonography. Plasma dilution derived from serial hemoglobin concentration and red blood cell count served as input variables for group and individual fluid volume kinetic analyses using a non-linear mixed effects model. In general, the distribution of all IV fluids was rapid, while elimination was slow. The half-lives of PLA, HS, and HES were 49, 319, and 104 min, respectively. The prescribed fluid doses for PLA, HS, and HES resulted in similar peak plasma volume expansion of 27–30%. The potency of HS was 6 times higher than PLA and 1.7 times greater than HES, while HES was 3.5 times more potent than PLA. Simulation of ideal fluid prescriptions to achieve and maintain 15 or 30% plasma volume expansion revealed the importance of a substantial reduction in infusion rates following initial IV fluid bolus. In conclusion, volume kinetic analysis is a feasible research tool that can provide data on IV fluid kinetics and body water physiology in cats. The rapid distribution but slow elimination of IV fluids in healthy conscious cats is consistent with anecdotal reports of fluid overload susceptibility in cats and warrants further investigation.

The Effects of Acute and Chronic Inflammation on the Dynamics of Fluid Shift of Ringer's Solution and Hemodynamics during Surgery

The aim of this study was to investigate the influences of acute and chronic inflammation on the dynamics of fluid shift of Ringer's solution and hemodynamics in patients during surgery. Thirty-seven patients with the American Society of Anesthesiologists (ASA) grades I-II were enrolled and allocated to two study groups according to the type of disease and operation and inflammation, including patients undergoing emergency appendectomy (Acute group, n = 19) and patients undergoing elective cholecystectomy (Chronic group, n = 18). All of the patients were administered 15 mL/kg of Ringer's lactated (LR) solution at a constant rate over 35 min before the induction of anesthesia. Plasma dilution (PD), volume expansion (VE), volume expansion efficiency (VEE), and extravascular volume (EVV) were calculated based on the concentration of hemoglobin within 2 h post-infusion. Heart rate (HR), arterial blood pressure and urine output were also recorded. PD and VE peaked at the end of infusion, while VEE peaked at the beginning of infusion in all of the patients. After infusion, PD, VE and VEE in the Acute group were all higher than those in the Chronic group (p < 0.05). PD and VE were higher during anesthesia or surgery than during awake or non-surgery (p < 0.001). The mean arterial pressure (MAP) and diastolic pressure (DBP) in the Acute group were significantly lower (p < 0.001) and HR was significantly higher (p < 0.001) than in the Chronic group during the study periods. It was suggested that patients with acute inflammation be treated with individualized fluid therapy during surgery.

Perfusion indices can predict early volume depletion in a blood donor model

INTRODUCTION

Blood donation from healthy donors is used experimental model that surrogates for class 1 hemorrhage in humans. We examined changes in the perfusion index (PI) and plethysmographic variability index (PVI) in healthy blood donors after donating a unit of blood, and we evaluated the usability of these indices in detecting blood loss volumes of less than 750 mL (class 1 hemorrhagic shock trauma patients).

MATERIALS AND METHODS

This study is a prospective, cross-sectional study. 180 healthy volunteers aged 18 and over, who donated blood at the local blood bank, were included in the study consecutively. The age, gender, and body mass index of the volunteers were recorded and, before and after the blood donation, the vital signs and perfusion indices were measured.

RESULTS

Of the donors, 61.7% were men (n = 111), and the median age of all donors was 32 (IQR: 21-39). A statistically significant difference was found between the hemodynamic parameters and PIs before and after the blood donation (p < 0.01 for all parameters; median difference of PI [- 1.45, 95% CI: (- 0.9)-( - 2)], median difference of PVI [6, 95% CI: 7.77-4.23].

CONCLUSION

We evaluated the perfusion indices in the early diagnosis of blood volume loss in patients admitted to the emergency department due to trauma. After the participants donated one unit of blood, we found that their PI decreased and PVI increased compared to the measurements before the blood donation. Considering that major bleeding starts in the very early stage as minor bleeding, it is essential for emergency physicians to recognize class 1 hemorrhagic shock patients. Further, non-invasive and straightforward procedures, such as measuring PI and PVI, can be particularly useful in identifying blood loss volumes of less than 750 mL.

Unraveling the molecular pathobiology of vocal fold systemic dehydration using an in vivo rabbit model

Vocal folds are a viscoelastic multilayered structure responsible for voice production. Vocal fold epithelial damage may weaken the protection of deeper layers of lamina propria and thyroarytenoid muscle and impair voice production. Systemic dehydration can adversely affect vocal function by creating suboptimal biomechanical conditions for vocal fold vibration. However, the molecular pathobiology of systemically dehydrated vocal folds is poorly understood. We used an in vivo rabbit model to investigate the complete gene expression profile of systemically dehydrated vocal folds. The RNA-Seq based transcriptome revealed 203 differentially expressed (DE) vocal fold genes due to systemic dehydration. Interestingly, function enrichment analysis showed downregulation of genes involved in cell adhesion, cell junction, inflammation, and upregulation of genes involved in cell proliferation. RT-qPCR validation was performed for a subset of DE genes and confirmed the downregulation of DSG1, CDH3, NECTIN1, SDC1, S100A9, SPINK5, ECM1, IL1A, and IL36A genes. In addition, the upregulation of the transcription factor NR4A3 gene involved in epithelial cell proliferation was validated. Taken together, these results suggest an alteration of the vocal fold epithelial barrier independent of inflammation, which could indicate a disruption and remodeling of the epithelial barrier integrity. This transcriptome provides a first global picture of the molecular changes in vocal fold tissue in response to systemic dehydration. The alterations observed at the transcriptional level help to understand the pathobiology of dehydration in voice function and highlight the benefits of hydration in voice therapy.

Understanding volume kinetics

The distribution and elimination kinetics of the water volume in infusion fluids can be studied by volume kinetics. The approach is a modification of drug pharmacokinetics and uses repeated measurements of blood hemoglobin and urinary excretion as input variables in (usually) a two-compartment model with expandable walls. Study results show that crystalloid fluid has a distribution phase that gives these fluids a plasma volume expansion amounting to 50%-60% of the infused volume as long as the infusion lasts, while the fraction is reduced to 15%-20% within 30 minutes after the infusion ends. Small volumes of crystalloid barely distribute to the interstitium, whereas rapid infusions tend to cause edema. Fluid elimination is very slow during general anesthesia due to the vasodilatation-induced reduction of the arterial pressure, whereas elimination is less affected by hemorrhage. The half-life is twice as long for saline than for Ringer solutions. Elimination is slower in conscious males than conscious females, and high red blood cell and thrombocyte counts retard both distribution and re-distribution. Children have faster turnover than adults. Plasma volume expansions are similar for glucose solutions and Ringer's, but the expansion duration is shorter for glucose. Concentrated urine before and during infusion slows down the elimination of crystalloid fluid. Colloid fluids have no distribution phase, an intravascular persistence half-life of 2-3 hours, and-at least for hydroxyethyl starch-the ability to reduce the effect of subsequently infused crystalloids. Accelerated distribution due to degradation of the endothelial glycocalyx layer has not yet been demonstrated.

Fluid management in perioperative and critically ill patients

Fluid therapy to restore and/or maintain tissue perfusion may affect patient outcomes in perioperative, emergency, and intensive care. Kinetic analyses and outcome-oriented studies have provided more insight into fluid management. Crystalloids are slowly distributed to the interstitial space, and the efficiency (proportion of infused fluid retained in the bloodstream) is 50%−75% as long as infusion continues and may increase up to 100% when the arterial pressure has decreased. Elimination of the infused fluid during general anesthesia and surgery is very slow, amounting to only 10%–20% compared with that in conscious patients. When the endothelial glycocalyx layer is degraded in sepsis or trauma-induced systemic inflammation, turnover of colloids and crystalloids is accelerated and the efficiency is reduced, which may lead to tissue edema, inflammation, poor wound healing, and organ dysfunction. Balanced crystalloids are pragmatic initial resuscitation fluids and improve patient outcomes compared to saline (0.9% sodium chloride). Albumin may be beneficial, but other synthetic colloids appear to increase the risk of acute kidney injury and death among patients in the intensive care unit. Fluid kinetics is likely to change based on patient physiological conditions (e.g., general anesthesia, surgery, stress, dehydration, blood pressure, or inflammation) and fluid types. To maximize efficacy and minimize iatrogenic side effects, fluids should be prescribed based on individual patient factors, disease states, and other treatment remedies.

Prediction of Shock by Peripheral Perfusion Index

OBJECTIVE

To detect occurrence of clinical shock and impending shock by monitoring Peripheral Perfusion Index (PI).

METHODS

In this study, 100 children aged 1 mo to 12 y of age who needed hemodynamic monitoring were included and categorized into five age groups. Demographic data, nutritional status, vital parameters, perfusion index and laboratory parameters were recorded. Hemodynamic monitoring was done for 48 h. In total, 65 and 35 children were admitted with and without features of shock respectively. Nine hundred thirty six hemodynamic measurements were taken and analyzed. Correlation between perfusion index, blood pressures and clinically assessed shock were done.

RESULTS

Clinical shock can be reasonably detected when perfusion index value is less than 1.15 in children less than 3 y of age, less than 1.25 in 3 to 10 y of age and less than 1.55 in 10 to 12 y of age. These values had high sensitivity and low false positivity in detecting clinically assessed shock in that particular age group. PI had good correlation with pulse pressure and systolic blood pressure in all age groups and weak correlation with mean arterial blood pressure and diastolic blood pressure. A 57% reduction in PI value from the baseline value may predict impending shock in children.

CONCLUSION

Perfusion index can be used as a non-invasive, continuous parameter to monitor peripheral perfusion in children and to detect impending shock.

The half-life of infusion fluids: An educational review

Supplemental Digital Content is available in the text

An understanding of the half-life (T_1/2) of infused fluids can help prevent iatrogenic problems such as volume overload and postoperative interstitial oedema. Simulations show that a prolongation of the T_1/2 for crystalloid fluid increases the plasma volume and promotes accumulation of fluid in the interstitial fluid space. The T_1/2 for crystalloids is usually 20 to 40 min in conscious humans but might extend to 80 min or longer in the presence of preoperative stress, dehydration, blood loss of <1 l or pregnancy.

The longest T_1/2 measured amounts to between 3 and 8 h and occurs during surgery and general anaesthesia with mechanical ventilation. This situation lasts as long as the anaesthesia. The mechanisms for the long T_1/2 are only partly understood, but involve adrenergic receptors and increased renin and aldosterone release. In contrast, the T_1/2 during the postoperative period is usually short, about 15 to 20 min, at least in response to new fluid.

The commonly used colloid fluids have an intravascular persistence T_1/2 of 2 to 3 h, which is shortened by inflammation. The fact that the elimination T_1/2 of the infused macromolecules is 2 to 6 times longer shows that they also reside outside the bloodstream. With a colloid, fluid volume is eliminated in line with its intravascular persistence, but there is insufficient data to know if this is the same in the clinical setting.

Comparison of the hemodynamics and dynamics of fluid shift of Ringer's solution before surgery in children and adults

The present study investigated the hemodynamics, vascular and extravascular volume expansion induced by infusion of lactated Ringer's solution in children and adults before surgery. This was a prospective randomized double-blind study. A total of 28 patients (14 children and 14 adult patients; American Society of Anesthesiology status I) scheduled for similar minor pelvic, anal rectal or lower limb surgery were recruited for the present study. All patients were administered with 10 ml/kg of lactated Ringer's solution at a constant rate over 20 min. After fluid infusion, plasma dilutions were calculated based on the concentration of hemoglobin. Heart rate (HR), mean arterial pressure (MAP) and urine output were measured before anesthesia was administered for surgery. Results demonstrated that the plasma dilution within 90 min of infusion initiation of lactated Ringer's solution was less pronounced in children compared with adult patients (0.07 vs. 0.16; P<0.001). Children also excreted more of the infused fluid through the kidney within 90 min of infusion initiation than the adults (55% vs. 24%; P=0.01). Following completion of fluid infusion, the volume expansion efficiency was higher in adults [0.82 (0.52-1.00)] than in children [0.46 (0.26-0.68)]. The relative changes in HR were significantly greater in children than in adults 15-60 min after infusion initiation (P<0.01). After 60 min, HRs were comparable between the groups; however, MAP declined significantly from 25-90 min after infusion initiation in children (P<0.05), yet remained nearly constant in adults (P>0.05). Simple regression analysis revealed a positive relationship between the relative changes in MAP and the plasma dilution, and the reduction in MAP in children was able to explain 47% of the variation in plasma dilution (R²=0.47; P=0.007). In conclusion, different hemodynamics and dynamics of fluid shift of Ringer's solution prior to surgery in children and adults may provide anesthesiologists with new information of how to administer fluid treatment for each patient.

The elimination half-life of crystalloid fluid is shorter in female than in male volunteers: a retrospective population kinetic analysis

Background

A recent review article suggests that elimination of infused crystalloid fluid might occur faster in females than in males. To study this question, a population kinetic analysis was performed to compare the turnover of buffered Ringer’s solution when infused at different rates in males and females.

Methods

Data were retrieved from seven series of experiments where 44 intravenous infusions of Ringer’s acetate had been given to female volunteers and 67 to male volunteers. Frequent measurements of the blood hemoglobin and the urinary excretion were used as input in a kinetic two-volume model with micro-constants and covariates, using a nonlinear mixed effects software. The key outcome measure was the rate of irreversible elimination of infused fluid, which was expressed as the half-life, obtained as the excreted urine divided by the modeled plasma volume expansion over time.

Results

The half-life amounted to 24 min (95 % confidence interval, 21–27) in the females and 38 min (33–42) in the males. The urinary excretion differed somewhat less than suggested by these figures during the experimental period (3–4 h) because the plasma volume became less expanded in the females. This was due to that fluid that had been distributed peripheral tissues (the interstitium) returned slightly more slowly to the central fluid space (the plasma) in the females. Gender did not serve as a statistically significant covariate to other rate constants in the kinetic model.

Conclusions

The half-life of infused Ringer’s acetate was 60 % longer in healthy male volunteers than in female volunteers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13293-016-0105-7) contains supplementary material, which is available to authorized users.

Distribution of crystalloid fluid changes with the rate of infusion: a population-based study

BACKGROUND

Crystalloid fluid requires 30 min for complete distribution throughout the extracellular fluid space and tends to cause long-standing peripheral edema. A kinetic analysis of the distribution of Ringer's acetate with increasing infusion rates was performed to obtain a better understanding of these characteristics of crystalloids.

METHODS

Data were retrieved from six studies in which 76 volunteers and preoperative patients had received between 300 ml and 2375 ml of Ringer's acetate solution at a rate of 20-80 ml/min (0.33-0.83 ml/min/kg). Serial measurements of the blood hemoglobin concentration were used as inputs in a kinetic analysis based on a two-volume model with micro-constants, using software for nonlinear mixed effects.

RESULTS

The micro-constants describing distribution (k12) and elimination (k10) were unchanged when the rate of infusion increased, with half-times of 16 and 26 min, respectively. In contrast, the micro-constant describing how rapidly the already distributed fluid left the peripheral space (k21) decreased by 90% when the fluid was infused more rapidly, corresponding to an increase in the half-time from 3 to 30 min. The central volume of distribution (V(c)) doubled.

CONCLUSION

The return of Ringer's acetate from the peripheral fluid compartment to the plasma was slower with high than with low infusion rates. Edema is a normal consequence of plasma volume expansion with this fluid, even in healthy volunteers. The results are consistent with the view that the viscoelastic properties of the interstitial matrix are responsible for the distribution and redistribution characteristics of crystalloid fluid.

Dehydration and fluid volume kinetics before major open abdominal surgery

INTRODUCTION

Assessment of dehydration in the preoperative setting is of potential clinical value. The present study uses urine analysis and plasma volume kinetics, which have both been validated against induced changes in body water in volunteers, to study the incidence and severity of dehydration before open abdominal surgery begins.

METHODS

Thirty patients (mean age 64 years) had their urine analysed before major elective open abdominal surgery for colour, specific weight, osmolality and creatinine. The results were scored and the mean taken to represent a 'dehydration index'. Thereafter, the patients received an infusion of 5 ml/kg of Ringer's acetate intravenously for over 15 min. Blood was sampled for 70 min and the blood haemoglobin concentration used to estimate the plasma volume kinetics.

RESULTS

Distribution of fluid occurred more slowly (P < 0.01) and the elimination half-life was twice as long (median 40 min, not significant) in the 11 patients (37%) diagnosed to be moderately dehydrated as compared with euhydrated patients. The dehydration index indicated that the fluid deficit in these patients corresponded to 2.5% of the body weight, whereas the deficit in the others was 1%. In contrast, the 11 patients who later developed postoperative nausea and vomiting had a very short elimination half-life, only 9 min (median, P < 0.01). These patients were usually euhydrated but had microalbuminuria (P < 0.03) and higher natriuresis (P < 0.01).

CONCLUSIONS

The degree of dehydration before major surgery was modest as evidenced both by urine sampling and volume kinetic analysis.

Preoperative urine-specific gravity and the incidence of complications after hip fracture surgery: A prospective, observational study

BACKGROUND

Mild to moderately severe dehydration is common in the elderly, but its relationship to surgical outcome is unclear.

OBJECTIVES

To study the incidence of dehydration prior to hip fracture surgery and its relationship to postoperative complications.

DESIGN

Prospective observational study.

SETTING

Operation department and orthopaedic ward at a regional hospital.

PATIENTS

Forty-five patients [median (interquartile range) age 78 (75 to 86) years] undergoing acute hip fracture surgery.

INTERVENTIONS

A urine sample was taken on admission to the operating theatre. Complications were assessed 2 days postoperatively using a check-list.

MAIN OUTCOME MEASURES

Dehydration was considered to be present if the urinary specific gravity was 1.020 or higher, indicating renal water conservation. The number and type of postoperative complications were recorded.

RESULTS

Dehydration was present in one third of the patients. Sixty percent of these patients had at least one postoperative complication, whereas the corresponding proportion was 30% in the euhydrated patients (P < 0.01). Only one patient (3%) had more than one complication in the euhydrated group compared with six patients (40%) in the dehydrated group (P < 0.01). Euhydrated patients had a mean of 0.3 postoperative complications per surgery, whereas dehydrated patients scored 1.1 complications (P < 0.015). The higher incidence included confusion, arterial desaturation and cardiovascular events.

CONCLUSION

Dehydration before surgery nearly quadrupled the number of postoperative complications after hip fracture repair.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT 01294930.

Dose and type of crystalloid fluid therapy in adult hospitalized patients

OBJECTIVE

In this narrative review, an overview is given of the pros and cons of various crystalloid fluids used for infusion during initial resuscitation or maintenance phases in adult hospitalized patients. Special emphasis is given on dose, composition of fluids, presence of buffers (in balanced solutions) and electrolytes, according to recent literature. We also review the use of hypertonic solutions.

METHODS

We extracted relevant clinical literature in English specifically examining patient-oriented outcomes related to fluid volume and type.

RESULTS

A restrictive fluid therapy prevents complications seen with liberal, large-volume therapy, even though restrictive fluid loading with crystalloids may not demonstrate large hemodynamic effects in surgical or septic patients. Hypertonic solutions may serve the purpose of small volume resuscitation but carry the disadvantage of hypernatremia. Hypotonic solutions are contraindicated in (impending) cerebral edema, whereas hypertonic solutions are probably more helpful in ameliorating than in preventing this condition and improving outcome. Balanced solutions offer a better approach for plasma composition than unbalanced ones, and the evidence for benefits in patient morbidity and mortality is increasing, particularly by helping to prevent acute kidney injury.

CONCLUSIONS

Isotonic and hypertonic crystalloid fluids are the fluids of choice for resuscitation from hypovolemia and shock. The evidence that balanced solutions are superior to unbalanced ones is increasing. Hypertonic saline is effective in mannitol-refractory intracranial hypertension, whereas hypotonic solutions are contraindicated in this condition.

Interactions between the volume effects of hydroxyethyl starch 130/0.4 and Ringer´s acetate

Introduction

The turnover of Ringer´s solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. The present study evaluates whether the kinetics is affected by previous infusion of colloid fluid.

Methods

Ten male volunteers with a mean age of 22 years underwent three infusion experiments, on separate days and in random order. The experiments included 10 mL/kg of 6% hydroxyethyl starch 130/0.4 (Voluven™), 20 mL/kg of Ringer's acetate, and a combination of both, where Ringer´s was administered 75 minutes after the starch infusion ended. The kinetics of the volume expansion was analysed by non-linear least- squares regression, based on urinary excretion and serial measurement of blood haemoglobin concentration for up to 420 minutes.

Results

The mean volume of distribution of the starch was 3.12 L which agreed well with the plasma volume (3.14 L) estimated by anthropometry. The volume expansion following the infusion of starch showed monoexponential elimination kinetics with a half-life of two hours. Two interaction effects were found when Ringer´s acetate was infused after the starch. First, there was a higher tendency for Ringer´s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer´s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer´s acetate was five times longer when administered after the starch (88 versus 497 minutes, P <0.02).

Conclusions

Starch promoted peripheral accumulation of the later infused Ringer´s acetate solution and markedly prolonged the elimination half-life.

Trial registration

ClinicalTrials.gov: NCT01195025