Balanced vs unbalanced crystalloid resuscitation in a near-fatal model of hemorrhagic shock and the effects on renal oxygenation, oxidative stress, and inflammation

Perioperative balanced crystalloids versus normal saline during kidney transplantation: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In kidney transplant (KT) surgery, the perioperative administration of intravenous (IV) fluids plays a crucial role, with potential effects on graft function. Our meta-analysis aims to assess the post-KT outcomes of perioperative balanced crystalloids (BC) versus normal saline (NS).

METHODS

We conducted a comprehensive search across five databases to identify relevant randomized controlled trials (RCTs). The search results were imported into Covidence for article eligibility screening, and all relevant outcome data were synthesized using risk ratios (RR) or mean differences (MD) with 95% confidence intervals (CIs) in meta-analysis models within RevMan 5.4.

PROSPERO ID

CRD42023448457.

RESULTS

Pooled data from 15 RCTs with 2,008 participants showed that the rate of delayed graft function (DGF) was significantly lower with BC (RR: 0.78, 95% CI [0.68, 0.91], P = 0.0009). Also, BC was associated with significantly higher post-op blood pH (MD: 0.05, 95% CI [0.03, 0.07], P < 0.01), lower serum chloride (MD: - 7.31, 95% CI [- 10.58, - 3.77], P < 0.01), and sodium (MD: - 1.94, 95% CI [- 3.32, - 0.55], P = 0.006) as compared to NS. However, serum potassium, serum creatinine, and urine output at POD 1 to 7 did not differ between the two groups.

CONCLUSION

BC significantly reduced the incidence of DGF, resulting in more stable post-operative acid-base parameters, and lower chloride levels compared to NS. Hence, substituting NS with BC offers a strategy to protect grafts from acidotic and hyperchloremic insults, optimizing KT outcomes.

DNA-PKcs Phosphorylates Cofilin2 to Induce Endothelial Dysfunction and Microcirculatory Disorder in Endotoxemic Cardiomyopathy

The presence of endotoxemia is strongly linked to the development of endothelial dysfunction and disruption of myocardial microvascular reactivity. These factors play a crucial role in the progression of endotoxemic cardiomyopathy. Sepsis-related multiorgan damage involves the participation of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). However, whether DNA-PKcs contributes to endothelial dysfunction and myocardial microvascular dysfunction during endotoxemia remains unclear. Hence, we conducted experiments in mice subjected to lipopolysaccharide (LPS)-induced endotoxemic cardiomyopathy, as well as assays in primary mouse cardiac microvascular endothelial cells. Results showed that endothelial-cell-specific DNA-PKcs ablation markedly attenuated DNA damage, sustained microvessel perfusion, improved endothelial barrier function, inhibited capillary inflammation, restored endothelium-dependent vasodilation, and improved heart function under endotoxemic conditions. Furthermore, we show that upon LPS stress, DNA-PKcs recognizes a TQ motif in cofilin2 and consequently induces its phosphorylation at Thr25. Phosphorylated cofilin2 shows increased affinity for F-actin and promotes F-actin depolymerization, resulting into disruption of the endothelial barrier integrity, microvascular inflammation, and defective eNOS-dependent vasodilation. Accordingly, cofilin2-knockin mice expressing a phospho-defective (T25A) cofilin2 mutant protein showed improved endothelial integrity and myocardial microvascular function upon induction of endotoxemic cardiomyopathy. These findings highlight a novel mechanism whereby DNA-PKcs mediates cofilin2Thr25 phosphorylation and subsequent F-actin depolymerization to contribute to endotoxemia-related cardiac microvascular dysfunction.

[Prehospital management in trauma patients and the increasing number of helicopter EMS transportations : An epidemiological study of the TraumaRegister DGU®]

BACKGROUND/OBJECTIVE

To compare the prehospital treatment modalities and intervention regimens for major trauma patients with comparable injury patterns between Austria and Germany.

PATIENTS AND METHODS

This analysis is based on data retrieved from the TraumaRegister DGU®. Data included severely injured trauma patients with an injury severity score (ISS) ≥ 16, an age ≥ 16 years, and who were primarily admitted to an Austrian (n = 4186) or German (n = 41,484) level I trauma center (TC) from 2008 to 2017. Investigated endpoints included prehospital times and interventions performed until final hospital admission.

RESULTS

The cumulative time for transportation from the site of the accident to the hospital did not significantly differ between the countries (62 min in Austria, 65 min in Germany). Overall, 53% of all trauma patients in Austria were transported to the hospital with a helicopter compared to 37% in Germany (p < 0.001). The rate of intubation was 48% in both countries, the number of chest tubes placed (5.7% Germany, 4.9% Austria), and the frequency of administered catecholamines (13.4% Germany, 12.3% Austria) were comparable (Φ = 0.00). Hemodynamic instability (systolic blood pressure, BP ≤ 90 mmHg) upon arrival in the TC was higher in Austria (20.6% vs. 14.7% in Germany; p < 0.001). A median of 500 mL of fluid was administered in Austria, whereas in Germany 1000 mL was infused (p < 0.001). Patient demographics did not reveal a relationship (Φ = 0.00) between both countries, and the majority of patients sustained a blunt trauma (96%). The observed ASA score of 3-4 was 16.8% in Germany versus 11.9% in Austria.

CONCLUSION

Significantly more helicopter EMS transportations (HEMS) were carried out in Austria. The authors suggest implementing international guidelines to explicitly use the HEMS system for trauma patients only a) for the rescue/care of people who have had an accident or are in life-threatening situations, b) for the transport of emergency patients with ISS > 16, c) for transportation of rescue or recovery personnel to hard to reach regions or, d) for the transport of medicinal products, especially blood products, organ transplants or medical devices.

Hypervolemia suppresses dilutional anaemic injury in a rat model of haemodilution

Background and Objectives

Haemodilution leads to complications in clinical practice. It is exactly unknown whether this damage is caused by the fluid or by the stretching of the vascular bed. We aimed to compare two different haemodilution techniques at the same anaemic level.

Methods

Normovolemic or hypervolemic haemodilution was performed on twelve adult male Wistar rats. In the normovolemic procedure, blood was withdrawn and instantaneously administered with similar amounts of 6% hydroxyethyl starch (HES 130/0.4). Fluid was administered without withdrawing blood in the hypervolemic procedure. In both models, a 25% haematocrit level was targeted and kept at this level for 90 min to deepen the anaemia effect. Besides haemodynamics measurement, renal function (creatinine, blood urea nitrogen) and injury (tissue norepinephrine, malondialdehyde) were evaluated. Also, systemic hypoxia (lactate), oxidative stress (malondialdehyde, ischaemia-modified albumin), inflammation (tumour necrosis factor-alpha [TNF-α]), osmotic stress, adrenal stress (norepinephrine, epinephrine), and vascular stretching (atrial natriuretic peptide [ANP]) were assessed.

Results

Arterial pressure in the normovolemic group was lower than in the hypervolemic group. Serum creatinine, blood urea nitrogen, and lactate levels were higher in the normovolemic group. Tissue norepinephrine and malondialdehyde levels were higher in the normovolemic group. Serum ANP, malondialdehyde, ischaemia-modified albumin, free haemoglobin, syndecan-1, and TNF-α were higher in both groups compared to respective baseline.

Conclusions

Normovolemic haemodilution may lead to hypoxic kidney injury. The hypervolemic state may be advantageous if fluid is to be administered. Thus, the effect of the fluid itself can be relatively masked.

Investigating influences of intravenous fluids on HUVEC and U937 monocyte cell lines using the magnetic levitation method

Intravenous fluids are being widely used in patients of all ages for preventing or treating dehydration in the intensive care units, surgeries in the operation rooms, or administering chemotherapeutic drugs at hospitals. Dextrose, Ringer, and NaCl solutions are widely received as intravenous fluids by hospitalized patients. Despite their widespread administration for over 100 years, studies on their influences on different cell types have been very limited. Increasing evidence suggests that treatment outcomes might be altered by the choice of the administered intravenous fluids. In this study, we investigated the influences of intravenous fluids on human endothelial (HUVEC) and monocyte (U937) cell lines using the magnetic levitation technique. Our magnetic levitation platform provides label-free manipulation of single cells without altering their phenotypic or genetic properties. It allows for monitoring and quantifying behavior of single cells by measuring their levitation heights, deformation indices, and areas. Our results indicate that HUVEC and U937 cell lines respond differently to different intravenous fluids. Dextrose solution decreased the viability of both cell lines while increasing the heterogeneity of areas, deformation, and levitation heights of HUVEC cells. We strongly believe that improved outcomes can be achieved when the influences of intravenous fluids on different cell types are revealed using robust, label-free, and efficient methods.

Intra-renal microcirculatory alterations on non-traumatic hemorrhagic shock induced acute kidney injury in pigs

Acute kidney injury (AKI) is frequently seen in patients with hemorrhagic shock due to hypotension, tissue hypoxia, and inflammation despite adequate resuscitation. There is a lack of information concerning the alteration of renal microcirculation and perfusion during shock and resuscitation. The aim of this study was to investigate the possible role of renal microcirculatory alterations on development of renal dysfunction in a pig model of non-traumatic hemorrhagic shock (HS) induced AKI.Fully instrumented female pigs were divided into the two groups as Control (n = 6) and HS (n = 11). HS was achieved by withdrawing blood until mean arterial pressure (MAP) reached around 50 mmHg. After an hour cessation period, fluid resuscitation with balanced crystalloid was started for the duration of 1 h. The systemic and renal hemodynamics, renal microcirculatory perfusion (contrast-enhanced ultrasound (CEUS)) and the sublingual microcirculation were measured.CEUS peak enhancement was significantly increased in HS during shock, early-, and late resuscitation indicating perfusion defects in the renal cortex (p < 0.05 vs. baseline, BL) despite a stable renal blood flow (RBF) and urine output. Following normalization of systemic hemodynamics, we observed persistent hypoxia (high lactate) and high red blood cell (RBC) velocity just after initiation of resuscitation resulting in further endothelial and renal damage as shown by increased plasma sialic acid (p < 0.05 vs. BL) and NGAL levels. We also showed that total vessel density (TVD) and functional capillary density (FCD) were depleted during resuscitation (p < 0.05).In this study, we showed that the correction of systemic hemodynamic variables may not be accompanied with the improvement of renal cortical perfusion, intra-renal blood volume and renal damage following fluid resuscitation. We suggest that the measurement of renal injury biomarkers, systemic and renal microcirculation can be used for guiding to the optimization of fluid therapies.

Resuscitating the Endothelial Glycocalyx in Trauma and Hemorrhagic Shock

The endothelium is lined by a protective mesh of proteins and carbohydrates called the endothelial glycocalyx (EG). This layer creates a negatively charged gel-like barrier between the vascular environment and the surface of the endothelial cell. When intact the EG serves multiple functions, including mechanotransduction, cell signaling, regulation of permeability and fluid exchange across the microvasculature, and management of cell-cell interactions. In trauma and/or hemorrhagic shock, the glycocalyx is broken down, resulting in the shedding of its individual components. The shedding of the EG is associated with increased systemic inflammation, microvascular permeability, and flow-induced vasodilation, leading to further physiologic derangements. Animal and human studies have shown that the greater the severity of the injury, the greater the degree of shedding, which is associated with poor patient outcomes. Additional studies have shown that prioritizing certain resuscitation fluids, such as plasma, cryoprecipitate, and whole blood over crystalloid shows improved outcomes in hemorrhaging patients, potentially through a decrease in EG shedding impacting downstream signaling. The purpose of the following paragraphs is to briefly describe the EG, review the impact of EG shedding and hemorrhagic shock, and begin entertaining the notion of directed resuscitation. Directed resuscitation emphasizes transitioning from macroscopic 1:1 resuscitation to efforts that focus on minimizing EG shedding and maximizing its reconstitution.

Endothelial and Glycocalyx Biomarkers in Children With Sepsis After One Bolus of Unbalanced or Balanced Crystalloids

OBJECTIVES

To assess the disruption of endothelial glycocalyx integrity in children with sepsis receiving fluid resuscitation with either balanced or unbalanced crystalloids. The primary outcome was endothelial glycocalyx disruption (using perfused boundary region >2 µm on sublingual video microscopy and syndecan-1 greater than 80 mg/dL) according to the type of crystalloid. The secondary outcomes were increased vascular permeability (using angiopoietin-2 level), apoptosis (using annexin A5 level), and associated clinical changes.

DESIGN

A single-center prospective cohort study from January to December 2021.

SETTING

Twelve medical-surgical PICU beds at a university hospital.

PATIENTS

Children with sepsis/septic shock before and after receiving fluid resuscitation with crystalloids for hemodynamic instability.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We included 106 patients (3.9 yr [interquartile range, 0.60-13.10 yr]); 58 of 106 (55%) received boluses of unbalanced crystalloid. This group had greater odds of endothelial glycocalyx degradation (84.5% vs 60.4%; adjusted odds ratio, 3.78; 95% CI, 1.49-9.58; p < 0.01) 6 hours after fluid administration, which correlated with increased angiopoietin-2 (rho = 0.4; p < 0.05) and elevated annexin A5 ( p = 0.04). This group also had greater odds of metabolic acidosis associated with elevated syndecan-1 (odds ratio [OR], 4.88; 95% CI, 1.23-28.08) and acute kidney injury (OR, 1.7; 95% CI, 1.12-3.18) associated with endothelial glycocalyx damage. The perfused boundary region returned to baseline 24 hours after receiving the crystalloid boluses.

CONCLUSIONS

Children with sepsis, particularly those who receive unbalanced crystalloid solutions during resuscitation, show loss and worsening of endothelial glycocalyx. The abnormality peaks at around 6 hours after fluid administration and is associated with greater odds of metabolic acidosis and acute kidney injury.

Manipulation of Nitric Oxide Levels via a Modified Hydroxyethyl Starch Molecule

INTRODUCTION

Although the improving effect of nitric oxide (NO) donors has experimentally been demonstrated in shock, there are still no NO donor medications clinically available. Thiol-nitrosothiol-hydroxyethyl starch (S-NO-HES) is a novel molecule consisting of NO coupled to a thiolated derivative of hydroxyethyl starch (HES). It was aimed to assess the ability of S-NO-HES to serve as an NO donor under a variety of in vitro simulated physiologic conditions, which might be the first step to qualify this molecule as a novel type of NO donor-fluid.

METHODS

We studied the effect of temperature on NO-releasing properties of S-NO-HES in blood, at 34°C, 37°C, and 41°C. Ascorbic acid (Asc) and amylase were also tested in a medium environment. In addition, we evaluated the activity of S-NO-HES in the isolated aortic ring and Langendorff-perfused heart setup.

RESULTS

The NO release property of S-NO-HES was found at any temperature. Asc led to a significant increase in the production of NO compared to S-NO-HES incubation (P < 0.05). The addition of amylase together with Asc to the medium further increased the release of NO (P < 0.05). S-NO-HES exerted significant vasodilatory effects on phenylephrine precontracted aortic rings that were dose-dependent (P < 0.01). Furthermore, S-NO-HES significantly increased the heart rate and additionally reduced the duration of the cardiac action potential, as indicated by a reduction of QTc-B values (P < 0.01).

CONCLUSIONS

We demonstrated for the first time that the S-NO-HES molecule exhibited its NO-releasing effects. The effectiveness of this new NO donor to substitute NO deficiency under septic conditions or in other indications needs to be studied.

Fluid Resuscitation Aggravates the Cellular Injury in a Hemorrhagic Shock Model

<b><i>Background:</i></b> Resuscitation is the initial step for hemorrhagic shock. However, there is still controversy as to which fluid achieves the best results clinically and experimentally. <b><i>Aim:</i></b> It was aimed to investigate the effects of 0.9% NaCl (sodium chloride) and 6% HES (hydroxyethyl starch) on the kidney and blood environment. <b><i>Methods:</i></b> Twenty-four male Wistar rats were assigned as control, shock, and resuscitated (colloid: 6% HES and crystalloid: 0.9% NaCl) groups. Besides hemodynamics (mean arterial pressure and shock index) monitoring and kidney function evaluation, hemolysis, oxidative stress, inflammation, and glycocalyx degradation were evaluated in the plasma and kidney. <b><i>Results:</i></b> (1) Macrohemodynamics were successfully restored by both fluids. (2) Although 3 times more crystalloid volume was applied compared to the colloid resuscitation, similar hematocrit levels were found in both resuscitation strategies (32.8 ± 2.3 vs. 33.3 ± 1.0). (3) NaCl resuscitation led to increases in the hemolytic index, catalytic iron, and sialic acid compared to control, while HES administration increased the levels of malondialdehyde, ischemia-modified albumin, and sialic acid. (4) However, both fluid resuscitation strategies could inhibit inflammation and oxidative stress in the kidney and restore kidney function parameters. <b><i>Conclusion:</i></b> Although both NaCl and HES resuscitation showed protection of the kidney function against oxidative stress and inflammation, these fluids initiated the injury process.

Effects of the Administration of Different Buffered Balanced Crystalloid Solutions on Acid-Base and Electrolyte Status in Dogs with Gastric Dilation-Volvulus Syndrome: a randomized clinical trial

OBJECTIVE

To investigate the effect of three different buffered balanced crystalloid solutions on acid-base status and electrolyte concentrations in dogs with gastric dilation-volvulus (GDV) syndrome.

METHODS

The study design was a prospective, randomized clinical trial of 40 dogs. The dogs were randomly assigned to one of three groups according to the fluid used: Hartmann's solution (H), Plasmalyte (PL), and Ringerfundin (RF). Hemoglobin, albumin, lactate, electrolyte, and acid-base parameters were determined before fluid administration (T0) and at the end of surgery (T1). Results were assessed by one-way ANOVA, Fisher's exact test, the Wilcoxon signed-rank test, the Kruskal-Wallis test, and a linear mixed-effect regression model. A significance level of 0.05 was used in all analyses.

RESULTS

Bicarbonate and base excess (BE) levels increased and chloride concentration decreased in the PL group; in contrast, strong ion difference apparent (SID_app) decreased and chloride concentration increased in the RF group. The mixed-effect model confirmed a significant interaction between the type of solution and time on the changes in bicarbonate, BE, anion gap (AG), SID_app, and chloride levels.

CLINICAL SIGNIFICANCE

Significantly different effects in acid-base parameters were observed in dogs after intravenous administration of H, PL, and RF. However, clinical significance of these changes is lacking, requiring further investigation in a larger randomized controlled clinical trial.

Kidney Microcirculation as a Target for Innovative Therapies in AKI

Acute kidney injury (AKI) is a serious multifactorial conditions accompanied by the loss of function and damage. The renal microcirculation plays a crucial role in maintaining the kidney’s functional and structural integrity for oxygen and nutrient supply and waste product removal. However, alterations in microcirculation and oxygenation due to renal perfusion defects, hypoxia, renal tubular, and endothelial damage can result in AKI and the loss of renal function regardless of systemic hemodynamic changes. The unique structural organization of the renal microvasculature and the presence of autoregulation make it difficult to understand the mechanisms and the occurrence of AKI following disorders such as septic, hemorrhagic, or cardiogenic shock; ischemia/reperfusion; chronic heart failure; cardiorenal syndrome; and hemodilution. In this review, we describe the organization of microcirculation, autoregulation, and pathophysiological alterations leading to AKI. We then suggest innovative therapies focused on the protection of the renal microcirculation and oxygenation to prevent AKI.

The Effects of Resuscitative Fluid Therapy on the Endothelial Surface Layer

The goal of resuscitative fluid therapy is to rapidly expand circulating blood volume in order to restore tissue perfusion. Although this therapy often serves to improve macrohemodynamic parameters, it can be associated with adverse effects on the microcirculation and endothelium. The endothelial surface layer (ESL) provides a protective barrier over the endothelium and is important for regulating transvascular fluid movement, vasomotor tone, coagulation, and inflammation. Shedding or thinning of the ESL can promote interstitial edema and inflammation and may cause microcirculatory dysfunction. The pathophysiologic perturbations of critical illness and rapid, large-volume fluid therapy both cause shedding or thinning of the ESL. Research suggests that restricting the volume of crystalloid, or “clear” fluid, may preserve some ESL integrity and improve outcome based on animal experimental models and preliminary clinical trials in people. This narrative review critically evaluates the evidence for the detrimental effects of resuscitative fluid therapy on the ESL and provides suggestions for future research directions in this field.

Association Between Unbalanced Solutions and Acute Kidney Injury During Fluid Resuscitation in Children With Sepsis

OBJECTIVE

To evaluate the outcomes of patients with sepsis-associated organ dysfunction and septic shock who receive fluid resuscitation with balanced and unbalanced solutions in a middle-income country.

DESIGN

An observational, analytical cohort study with propensity score matching (PSM) in children admitted to a pediatric intensive care unit (PICU). Patients from one month to 17 years old who required fluid boluses due to hemodynamic instability were included. The primary outcome was the presence of acute kidney injury and the secondary outcomes were the need to begin continuous renal replacement therapy (CRRT), metabolic acidosis, PICU length of stay and mortality.

MEASUREMENTS AND MAIN RESULTS

Out of the 1,074 admissions to the PICU during the study period, 99 patients had sepsis-associated organ dysfunction and septic shock. Propensity score matching was performed including each patient´s baseline characteristics. The median age was 9.9 months (IQR 4.9-22.2) with 55.5% of the patients being male. Acute kidney injury was seen less frequently in children who received a balanced solution than in those who received an unbalanced solution (20.3% vs 25.7% P = 0.006 ORa, 0.75; 95% CI, 0.65-0.87), adjusted for disease severity. In addition, the group that received balanced solutions had less need for CRRT (3.3 % vs 6.5%; P = 0.02 ORa 0.48; 95% CI, 0.36-0.64) and a shorter PICU stay (6 days IQR 4.4-20.2 vs 10.2 days IQR 4.7-26; P < 0.001) than the group with unbalanced solutions. We found no difference in the frequency of metabolic acidosis (P = 0.37), hyperchloremia (P = 0.11) and mortality (P = 0.25) between the 2 groups.

CONCLUSION

In children with sepsis-associated organ dysfunction and septic shock, the use of unbalanced solutions for fluid resuscitation is associated with a higher frequency of acute kidney injury, a greater need for continuous renal support and a longer PICU stay compared to the use of balanced solutions, in a middle-income country.

The Impact of Intravenous Fluid Therapy on Acid-Base Status of Critically Ill Adults: A Stewart Approach-Based Perspective

One of the most important tasks of physicians working in intensive care units (ICUs) is to arrange intravenous fluid therapy. The primary indications of the need for intravenous fluid therapy in ICUs are in cases of resuscitation, maintenance, or replacement, but we also load intravenous fluid for purposes such as fluid creep (including drug dilution and keeping venous lines patent) as well as nutrition. However, in doing so, some facts are ignored or overlooked, resulting in an acid-base disturbance. Regardless of the type and content of the fluid entering the body through an intravenous route, it may impair the acid-base balance depending on the rate, volume, and duration of the administration. The mechanism involved in acid-base disturbances induced by intravenous fluid therapy is easier to understand with the help of the physical-chemical approach proposed by Canadian physiologist, Peter Stewart. It is possible to establish a quantitative link between fluid therapy and acid–base disturbance using the Stewart principles. However, it is not possible to accomplish this with the traditional approach; moreover, it may not be noticed sometimes due to the normalization of pH or standard base excess induced by compensatory mechanisms. The clinical significance of fluid-induced acid-base disturbances has not been completely clarified yet. Nevertheless, as fluid therapy may be the cause of unexplained acid-base disorders that may lead to confusion and elicit unnecessary investigation, more attention must be paid to understand this issue. Therefore, the aim of this paper is to address the effects of different types of fluid therapies on acid-base balance using the simplified perspective of Stewart principles. Overall, the paper intends to help recognize fluid-induced acid-base disturbance through bedside evaluation and choose an appropriate fluid by considering the acid-base status of a patient.

Etiology and Management of Acute Metabolic Acidosis: An Update

BACKGROUND

The etiology of acute metabolic acidosis (aMA) is heterogeneous, and the consequences are potentially life-threatening. The aim of this article was to summarize the causes and management of aMA from a clinician's perspective.

SUMMARY

We performed a systematic search on PubMed, applying the following search terms: "acute metabolic acidosis," "lactic acidosis," "metformin" AND "acidosis," "unbalanced solutions" AND "acidosis," "bicarbonate" AND "acidosis" AND "outcome," "acute metabolic acidosis" AND "management," and "acute metabolic acidosis" AND "renal replacement therapy (RRT)/dialysis." The literature search did not consider diabetic ketoacidosis at all. Lactic acidosis evolves from various conditions, either with or without systemic hypoxia. The incidence of metformin-associated aMA is actually quite low. Unbalanced electrolyte preparations can induce hyperchloremic aMA. The latter potentially worsens kidney-related outcome parameters. Nevertheless, prospective and controlled data are missing at the moment. Recently, bicarbonate has been shown to improve clinically relevant endpoints in the critically ill, even if higher pH values (>7.3) are targeted. New therapeutics for aMA control are under development, since bicarbonate treatment can induce serious side effects. Key Messages: aMA is a frequent and potentially life-threatening complication of various conditions. Lactic acidosis might occur even in the absence of systemic hypoxia. The incidence of metformin-associated aMA is comparably low. Unbalanced electrolyte solutions induce hyperchloremic aMA, which most likely worsens the renal prognosis of critically ill patients. Bicarbonate, although potentially deleterious due to increased carbon dioxide production with subsequent intracellular acidosis, improves kidney-related endpoints in the critically ill.

Assessment of sublingual microcirculation in critically ill patients: consensus and debate

The main concern in shock and resuscitation is whether the microcirculation can carry adequate oxygen to the tissues and remove waste. Identification of an intact coherence between macro- and microcirculation during states of shock and resuscitation shows a functioning regulatory mechanism. However, loss of hemodynamic coherence between the macro and microcirculation can be encountered frequently in sepsis, cardiogenic shock, or any hemodynamically compromised patient. This loss of hemodynamic coherence results in an improvement in macrohemodynamic parameters following resuscitation without a parallel improvement in microcirculation resulting in tissue hypoxia and tissue compromise. Hand-held vital microscopes (HVMs) can visualize the microcirculation and help to diagnose the nature of microcirculatory shock. Although treatment with the sole aim of recruiting the microcirculation is as yet not realized, interventions can be tailored to the needs of the patient while monitoring sublingual microcirculation. With the help of the newly introduced software, called MicroTools, we believe sublingual microcirculation monitoring and diagnosis will be an essential point-of-care tool in managing shock patients.

Resveratrol protects the mitochondria from vitrification injury in mouse 2-cell embryos

Mitochondria play a key role in embryo development by providing energy. However, vitrification often causes mitochondrion damage of embryo, which further impairs embryo development. Therefore, the efficiency of embryo development after vitrification could be improved by protecting mitochondrial function from vitrification injury. The purpose of this study was to investigate the effects of resveratrol on mitochondrial damage after vitrification. The results showed that vitrification induced the abnormal mitochondrial distribution and damage mitochondrial function of mouse 2-cell embryos. However, co-culturing with resveratrol for 2 h could repair the abnormal mitochondrial distribution and mitochondrial dysfunction of embryos after vitrification. More than anything, the subsequent development ability of vitrified-thawed 2-cell embryos was significantly higher than that with no resveratrol treatment. In conclusion, resveratrol could protect the mitochondrial from injury caused by vitrification.

Intravenous fluid therapy in the perioperative and critical care setting: Executive summary of the International Fluid Academy (IFA)

Intravenous fluid administration should be considered as any other pharmacological prescription. There are three main indications: resuscitation, replacement, and maintenance. Moreover, the impact of fluid administration as drug diluent or to preserve catheter patency, i.e., fluid creep, should also be considered. As for antibiotics, intravenous fluid administration should follow the four Ds: drug, dosing, duration, de-escalation. Among crystalloids, balanced solutions limit acid–base alterations and chloride load and should be preferred, as this likely prevents renal dysfunction. Among colloids, albumin, the only available natural colloid, may have beneficial effects. The last decade has seen growing interest in the potential harms related to fluid overloading. In the perioperative setting, appropriate fluid management that maintains adequate organ perfusion while limiting fluid administration should represent the standard of care. Protocols including a restrictive continuous fluid administration alongside bolus administration to achieve hemodynamic targets have been proposed. A similar approach should be considered also for critically ill patients, in whom increased endothelial permeability makes this strategy more relevant. Active de-escalation protocols may be necessary in a later phase. The R.O.S.E. conceptual model (Resuscitation, Optimization, Stabilization, Evacuation) summarizes accurately a dynamic approach to fluid therapy, maximizing benefits and minimizing harms. Even in specific categories of critically ill patients, i.e., with trauma or burns, fluid therapy should be carefully applied, considering the importance of their specific aims; maintaining peripheral oxygen delivery, while avoiding the consequences of fluid overload.

Effect of Polyethylene-glycolated Carboxyhemoglobin on Renal Microcirculation in a Rat Model of Hemorrhagic Shock

BACKGROUND

Primary resuscitation fluid to treat hemorrhagic shock remains controversial. Use of hydroxyethyl starches raised concerns of acute kidney injury. Polyethylene-glycolated carboxyhemoglobin, which has carbon monoxide-releasing molecules and oxygen-carrying properties, was hypothesized to sustain cortical renal microcirculatory PO2 after hemorrhagic shock and reduce kidney injury.

METHODS

Anesthetized and ventilated rats (n = 42) were subjected to pressure-controlled hemorrhagic shock for 1 h. Renal cortical PO2 was measured in exposed kidneys using a phosphorescence quenching method. Rats were randomly assigned to six groups: polyethylene-glycolated carboxyhemoglobin 320 mg · kg, 6% hydroxyethyl starch (130/0.4) in Ringer's acetate, blood retransfusion, diluted blood retransfusion (~4 g · dl), nonresuscitated animals, and time control. Nitric oxide and heme oxygenase 1 levels were determined in plasma. Kidney immunohistochemistry (histologic scores of neutrophil gelatinase-associated lipocalin and tumor necrosis factor-α) and tubular histologic damages analyses were performed.

RESULTS

Blood and diluted blood restored renal PO2 to 51 ± 5 mmHg (mean difference, -18; 95% CI, -26 to -11; P < 0.0001) and 47 ± 5 mmHg (mean difference, -23; 95% CI, -31 to -15; P < 0.0001), respectively, compared with 29 ± 8 mmHg for hydroxyethyl starch. No differences between polyethylene-glycolated carboxyhemoglobin and hydroxyethyl starch were observed (33 ± 7 mmHg vs. 29 ± 8 mmHg; mean difference, -5; 95% CI, -12 to 3; P = 0.387), but significantly less volume was administered (4.5 [3.3-6.2] vs. 8.5[7.7-11.4] ml; mean rank difference, 11.98; P = 0.387). Blood and diluted blood increased the plasma bioavailability of nitric oxide compared with hydroxyethyl starch (mean rank difference, -20.97; P = 0.004; and -17.13; P = 0.029, respectively). No changes in heme oxygenase 1 levels were observed. Polyethylene-glycolated carboxyhemoglobin limited tubular histologic damages compared with hydroxyethyl starch (mean rank difference, 60.12; P = 0.0012) with reduced neutrophil gelatinase-associated lipocalin (mean rank difference, 84.43; P < 0.0001) and tumor necrosis factor-α (mean rank difference, 49.67; P = 0.026) histologic scores.

CONCLUSIONS

Polyethylene-glycolated carboxyhemoglobin resuscitation did not improve renal PO2 but limited tubular histologic damages and neutrophil gelatinase-associated lipocalin upregulation after hemorrhage compared with hydroxyethyl starch, whereas a lower volume was required to sustain macrocirculation.

Resuscitation with Hydroxyethyl Starch Maintains Hemodynamic Coherence in Ovine Hemorrhagic Shock

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Fluid resuscitation in hemorrhagic shock aims to restore hemodynamics and repair altered microcirculation. Hemodynamic coherence is the concordant performance of macro- and microcirculation. The present study on fluid therapy in hemorrhagic shock hypothesized that the choice of fluid (0.9% sodium chloride [saline group] or balanced 6% hydroxyethyl starch 130/0.4 [hydroxyethyl starch group]) impacts on hemodynamic coherence.

Methods

After instrumentation, 10 sheep were bled up to 30 ml/kg body weight of blood stopping at a mean arterial pressure of 30 mmHg to establish hemorrhagic shock. To reestablish baseline mean arterial pressure, they received either saline or hydroxyethyl starch (each n = 5). Hemodynamic coherence was assessed by comparison of changes in mean arterial pressure and both perfused vessel density and microvascular flow index.

Results

Bleeding of 23 ml/kg blood [21; 30] (median [25th; 75th percentile]) in the saline group and 24 ml/kg [22; 25] (P = 0.916) in the hydroxyethyl starch group led to hemorrhagic shock. Fluid resuscitation reestablished baseline mean arterial pressure in all sheep of the hydroxyethyl starch group and in one sheep of the saline group. In the saline group 4,980 ml [3,312; 5,700] and in the hydroxyethyl starch group 610 ml [489; 615] of fluid were needed (P = 0.009). In hemorrhagic shock perfused vessel density (saline from 100% to 83% [49; 86]; hydroxyethyl starch from 100% to 74% [61; 80]) and microvascular flow index (saline from 3.1 [2.5; 3.3] to 2.0 [1.6; 2.3]; hydroxyethyl starch from 2.9 [2.9; 3.1] to 2.5 [2.3; 2.7]) decreased in both groups. After resuscitation both variables improved in the hydroxyethyl starch group (perfused vessel density: 125% [120; 147]; microvascular flow index: 3.4 [3.2; 3.5]), whereas in the saline group perfused vessel density further decreased (64% [62; 79]) and microvascular flow index increased less than in the hydroxyethyl starch group (2.7 [2.4; 2.8]; both P &lt; 0.001 for saline vs. hydroxyethyl starch).

Conclusions

Resuscitation with hydroxyethyl starch maintained coherence in hemorrhagic shock. In contrast, saline only improved macro- but not microcirculation. Hemodynamic coherence might be influenced by the choice of resuscitation fluid.

Low- Versus High-Chloride Content Intravenous Solutions for Critically Ill and Perioperative Adult Patients: A Systematic Review and Meta-analysis

BACKGROUND

To assess whether use of low-chloride solutions in unselected critically ill or perioperative adult patients for maintenance or resuscitation reduces mortality and renal replacement therapy (RRT) use when compared to high-chloride fluids.

METHODS

Systematic review and meta-analysis with random-effects inverse variance model. PubMed, Cochrane library, EMBASE, LILACS, and Web of Science were searched from inception to October 2016. Published and unpublished randomized controlled trials in any language that enrolled critically ill and/or perioperative adult patients and compared a low- to a highchloride solution for volume maintenance or resuscitation. The primary outcomes were mortality and RRT use. We conducted trial sequential analyses and assessed risk of bias of individual trials and the overall quality of evidence. Fifteen trials with 4067 patients, most at low risk of bias, were identified. Of those, only 11 and 10 trials had data on mortality and RRT use, respectively. A total of 3710 patients were included in the mortality analysis and 3724 in the RRT analysis.

RESULTS

No statistically significant impact on mortality (odds ratio, 0.90; 95% confidence interval, 0.69-1.17; P = .44; I = 0%) or RRT use (odds ratio, 1.12; 95% confidence interval, 0.80-1.58; P = .52; I = 0%) was found. Overall quality of evidence was low for both primary outcomes. Trial sequential analyses highlighted that the sample size needed was much larger than that available for properly powered outcome assessment.

CONCLUSIONS

The current evidence on low- versus high-chloride solutions for unselected critically ill or perioperative adult patients demonstrates no benefit, but suffers from considerable imprecision. We noted a limited exposure volume for study fluids and a relatively low risk of the populations in each study. Together with the relatively small pooled sample size, these data leave us underpowered to detect potentially important differences. Results from well-conducted, adequately powered randomized controlled trials examining sufficiently large fluid exposure are necessary.

Effect of early fluid resuscitation combined with low dose cyclophosphamide on intestinal barrier function in severe sepsis rats

To investigate the effect of early fluid resuscitation on intestinal microecology in rats with severe sepsis. The severe sepsis model used was mainly cecal ligation perforation (CLP) model. Male SD rats were randomly divided into five groups: sham, CLP, CLP + normal saline (NS), CLP + cyclophosphamide (CTX), and CLP + NS + CTX. (1) The levels of IL-6, IL-10, and TNF-α in peripheral blood were measured by ELISA. (2) The expression of occludin/β-action in colonic tissue of mice was examined by Western Blot. (3) The intestinal permeability was measured by FD70 detection. (4) The length of the chorionic membrane was measured by colon histopathological staining. (5) The intestinal epithelial cell apoptosis was measured with the apoptosis index. (1) The rat model of severe sepsis was successfully replicated, and the 7-day survival rate of sepsis mice in each group was analyzed. (2) The expression level of splenic junction protein and the pathological damage in colonic tissue of the severe sepsis mice was significantly different between sham, CLP, CTX, NS, and NS + CTX (P < 0.05). The expression of tight junction protein in the NS + CTX mice was the highest, and the pathological damage was the smallest. (3) The colonic tissue apoptosis and intestinal permeability in the severe sepsis mice were compared with those of the colon tissues (P < 0.05). (4) The expression levels of IL-6, IL-10, and TNF-α in peripheral blood were significantly increased after severe sepsis (P < 0.01). The expression of IL-6 and TNF-alpha in each treatment group decreased (P < 0.05), while the expression of IL-10 in NS + CTX group increased significantly (P < 0.01). (1) We successfully replicated the rat model of severe sepsis. (2) Early fluid intervention and cyclophosphamide treatment can significantly improve the 7-day survival rate of the sepsis mice. (3) The fluid resuscitation and cyclophosphamide can delay intestinal damage to the intestinal tract barrier function and play a protective role.

Fluid administration rate for uncontrolled intraabdominal hemorrhage in swine

Background

We hypothesized that slow crystalloid resuscitation would result in less blood loss and a smaller hemoglobin decrease compared to a rapid resuscitation during uncontrolled hemorrhage.

Methods

Anesthetized, splenectomized domestic swine underwent hepatic lobar hemitransection. Lactated Ringers was given at 150 or 20 mL/min IV (rapid vs. slow, respectively, N = 12 per group; limit of 100 mL/kg). Primary endpoints were blood loss and serum hemoglobin; secondary endpoints included survival, vital signs, coagulation parameters, and blood gases.

Results

The slow group had a less blood loss (1.6 vs. 2.7 L, respectively) and a higher final hemoglobin concentration (6.0 vs. 3.4 g/dL).

Conclusions

Using a fixed volume of crystalloid resuscitation in this porcine model of uncontrolled intraabdominal hemorrhage, a slow IV infusion rate produced less blood loss and a smaller hemoglobin decrease compared to rapid infusion.

Differences in capillary recruitment between cardiac surgery and septic patients after fluid resuscitation

BACKGROUND

Clinical evaluation of the effects of fluid therapy remains cumbersome and strategies are based on the assumption that normalization of macrohemodynamic variables will result in parallel improvement in organ perfusion. Recently, we and others suggested the use of direct in-vivo observation of the microcirculation to evaluate the effects of fluid therapy.

METHODS

A single-centre observational study, using in-vivo microscopy to assess total vessel density (TVD) in two subsets of ICU patients.

RESULTS

After fluid resuscitation TVD showed no difference between sepsis patients (N = 47) and cardiac surgery patients (N = 52): 18.4[16.8-20.8] vs 18.7[16.8-20.9] mm/mm², p = 0.59. In cardiac surgery patients there was a significant correlation between the amount of fluids administered and TVD, with an optimum in the third quartile. However, such correlation was absent in septic patients.

CONCLUSIONS

TVD after fluid administration is not different between 2 subtypes of intensive care patients. However, only in septic patients we observed a lack of coherence between the amount of fluids administered and TVD. Further research is needed to determine if TVD may serve as potential endpoint for fluid administration.

Sepsis-induced acute kidney injury: A disease of the microcirculation

AKI is a common complication of sepsis and is significantly associated with mortality. Sepsis accounts for more than 50% of the cases of AKI, with a mortality rate of up to 40%. The pathogenesis of septic AKI is complex, but there is emerging evidence that, at least in the first 48 hours, the defects may be functional rather than structural in nature. For example, septic AKI is associated with an absence of histopathological changes, but with microvascular abnormalities and tubular stress. In this context, renal medullary hypoxia due to redistribution of intra-renal perfusion is emerging as a critical mediator of septic AKI. Clinically, vasopressor drugs remain the cornerstone of therapy for maintenance of blood pressure and organ perfusion. However, in septic AKI, there is insensitivity to vasopressors such as norepinephrine, leading to persistent hypotension and organ failure. Vasopressin, angiotensin II, and, paradoxically, α₂ -adrenergic receptor agonists (clonidine and dexmedetomidine) may be feasible adjunct therapies for catecholamine-resistant vasodilatory shock. In this review, we outline the recent progress made in understanding how these drugs may influence the renal microcirculation, which represents a crucial step toward developing better approaches for the circulatory management of patients with septic AKI.

The anion study: effect of different crystalloid solutions on acid base balance, physiology, and survival in a rodent model of acute isovolaemic haemodilution

Background

Commercially available crystalloid solutions used for volume replacement do not exactly match the balance of electrolytes found in plasma. Large volume administration may lead to electrolyte imbalance and potential harm. We hypothesised that haemodilution using solutions containing different anions would result in diverse biochemical effects, particularly on acid-base status, and different outcomes.

Methods

Anaesthetised, fluid-resuscitated, male Wistar rats underwent isovolaemic haemodilution by removal of 10% blood volume every 15 min, followed by replacement with one of three crystalloid solutions based on acetate, lactate, or chloride. Fluids were administered in a protocolised manner to achieve euvolaemia based on echocardiography-derived left ventrical volumetric measures. Removed blood was sampled for plasma ions, acid-base status, haemoglobin, and glucose. This cycle was repeated at 15-min intervals until death. The primary endpoint was change in plasma bicarbonate within each fluid group. Secondary endpoints included time to death and cardiac function.

Results

During haemodilution, chloride-treated rats showed significantly greater decreases in plasma bicarbonate and strong ion difference levels compared with acetate- and lactate-treated rats. Time to death, total volume of fluid administered: chloride group 56 (3) ml, lactate group 62 (3) ml, and acetate group 65 (3) ml; haemodynamic and tissue oxygenation changes were, however, similar between groups.

Conclusions

With progressive haemodilution, resuscitation with a chloride-based solution induced more acidosis compared with lactate- and acetate-based solutions, but outcomes were similar. No short-term impact was seen from hyperchloraemia in this model.

0.9% NaCl (Normal Saline) - Perhaps not so normal after all?

Crystalloid infusion is widely employed in patient care for volume replacement and resuscitation. In the United States the crystalloid of choice is often normal saline. Surgeons and anesthesiologists have long preferred buffered solutions such as Ringer's Lactate and Plasma-Lyte A. Normal saline is the solution most widely employed in medical and pediatric care, as well as in hematology and transfusion medicine. However, there is growing concern that normal saline is more toxic than balanced, buffered crystalloids such as Plasma-Lyte and Lactated Ringer's. Normal saline is the only solution recommended for red cell washing, administration and salvage in the USA, but Plasma-Lyte A is also FDA approved for these purposes. Lactated Ringer's has been traditionally avoided in these applications due to concerns over clotting, but existing research suggests this is not likely a problem. In animal models and clinical studies in various settings, normal saline can cause metabolic acidosis, vascular and renal function changes, as well as abdominal pain in comparison with balanced crystalloids. The one extant randomized trial suggests that in very small volumes (2 l or less) normal saline is not more toxic than other crystalloids. Recent evidence suggests that normal saline causes substantially more in vitro hemolysis than Plasma-Lyte A and similar solutions during short term storage (24 hours) after washing or intraoperative salvage. There are now abundant data to raise concerns as to whether normal saline is the safest replacement solution in infusion therapy, red cell washing and salvage, apheresis and similar uses. In the USA, Plasma-Lyte A is also FDA approved for use with blood components and is likely a safer solution for these purposes. Its only disadvantage is a higher cost. Additional studies of the safety of normal saline for virtually all current clinical uses are needed. It seems likely that normal saline will eventually be abandoned in favor of safer, more physiologic crystalloid solutions in the coming years.

Hemorrhagic Shock and the Microvasculature

The microvasculature plays a central role in the pathophysiology of hemorrhagic shock and is also involved in arguably all therapeutic attempts to reverse or minimize the adverse consequences of shock. Microvascular studies specific to hemorrhagic shock were reviewed and broadly grouped depending on whether data were obtained on animal or human subjects. Dedicated sections were assigned to microcirculatory changes in specific organs, and major categories of pathophysiological alterations and mechanisms such as oxygen distribution, ischemia, inflammation, glycocalyx changes, vasomotion, endothelial dysfunction, and coagulopathy as well as biomarkers and some therapeutic strategies. Innovative experimental methods were also reviewed for quantitative microcirculatory assessment as it pertains to changes during hemorrhagic shock. The text and figures include representative quantitative microvascular data obtained in various organs and tissues such as skin, muscle, lung, liver, brain, heart, kidney, pancreas, intestines, and mesentery from various species including mice, rats, hamsters, sheep, swine, bats, and humans. Based on reviewed findings, a new integrative conceptual model is presented that includes about 100 systemic and local factors linked to microvessels in hemorrhagic shock. The combination of systemic measures with the understanding of these processes at the microvascular level is fundamental to further develop targeted and personalized interventions that will reduce tissue injury, organ dysfunction, and ultimately mortality due to hemorrhagic shock. Published 2018. Compr Physiol 8:61-101, 2018.

Balanced crystalloids for septic shock resuscitation

Timely fluid administration is crucial to maintain tissue perfusion in septic shock patients. However, the question concerning which fluid should be used for septic shock resuscitation remains a matter of debate. A growing body of evidence suggests that the type, amount and timing of fluid administration during the course of sepsis may affect patient outcomes. Crystalloids have been recommended as the first-line fluids for septic shock resuscitation. Nevertheless, given the inconclusive nature of the available literature, no definitive recommendations about the most appropriate crystalloid solution can be made. Resuscitation of septic and non-septic critically ill patients with unbalanced crystalloids, mainly 0.9% saline, has been associated with a higher incidence of acid-base balance and electrolyte disorders and might be associated with a higher incidence of acute kidney injury. This can result in greater demand for renal replacement therapy and increased mortality. Balanced crystalloids have been proposed as an alternative to unbalanced solutions in order to mitigate their detrimental effects. Nevertheless, the safety and effectiveness of balanced crystalloids for septic shock resuscitation need to be further addressed in a well-designed, multicenter, pragmatic, randomized controlled trial.

Low-volume resuscitation with normal saline is associated with microvascular endothelial dysfunction after hemorrhage in rats, compared to colloids and balanced crystalloids

Background

Restoration of endothelial glycocalyx (EG) barrier may be an essential therapeutic target for successful resuscitation. The aim of this study was to compare in vivo the effects of resuscitation with normal saline (NS) to lactated Ringer’s solution (LR), 5% albumin and fresh frozen plasma (FFP) on their ability to maintain EG and barrier function integrity, mitigate endothelial injury and inflammation, and restore vascular homeostasis after hemorrhagic shock.

Methods

Anesthetized rats (N = 36) were subjected to hemorrhagic shock (bled 40% of total blood volume), followed by resuscitation with 45 ml/kg NS or LR, or 15 ml/kg 5% albumin or FFP. Microhemodynamics, EG thickness, permeability, leukocyte rolling and adhesion were assessed in >180 vessels from cremaster muscle, as well as systemic measures.

Results

After hypotensive resuscitation, arterial pressure was 25% lower than baseline in all cohorts. Unlike FFP, resuscitation with crystalloids failed to restore EG thickness to baseline post shock and shedding of glycocalyx proteoglycan was significantly higher after NS. NS decreased blood flow and shear, and markedly increased permeability and leukocyte rolling/adhesion. In contrast, LR had lesser effects on increased permeability and leukocyte rolling. Albumin stabilized permeability and white blood cell (WBC) rolling/adhesion post shock, comparable to FFP.

Conclusions

Resuscitation with NS failed to inhibit syndecan-1 shedding and to repair the EG, which led to loss of endothelial barrier function (edema), decline in tissue perfusion and pronounced leukocyte rolling and adhesion. Detrimental effects of NS on endothelial and microvascular stabilization post shock may provide a pathophysiological basis to understand and prevent morbidity associated with iatrogenic resuscitation after hemorrhagic shock.

A LED-based phosphorimeter for measurement of microcirculatory oxygen pressure

Quantitative measurements of microcirculatory and tissue oxygenation are of prime importance in experimental research. The noninvasive phosphorescence quenching method has given further insight into the fundamental mechanisms of oxygen transport to healthy tissues and in models of disease. Phosphorimeters are devices dedicated to the study of phosphorescence quenching. The experimental applications of phosphorimeters range from measuring a specific oxygen partial pressure (Po2) in cellular organelles such as mitochondria, finding values of Po2 distributed over an organ or capillaries, to measuring microcirculatory Po2 changes simultaneously in several organ systems. Most of the current phosphorimeters use flash lamps as a light excitation source. However, a major drawback of flash lamps is their inherent plasma glow that persists for tens of microseconds after the primary discharge. This complex distributed excitation pattern generated by the flash lamp can lead to inaccurate Po2 readings unless a deconvolution analysis is performed. Using light-emitting diode (LED), a rectangular shaped light pulse can be generated that provides a more uniformly distributed excitation signal. This study presents the design and calibration process of an LED-based phosphorimeter (LED-P). The in vitro calibration of the LED-P using palladium(II)-meso-tetra(4-carboxyphenyl)-porphyrin (Pd-TCCP) as a phosphorescent dye is presented. The pH and temperature were altered to assess whether the decay times of the Pd-TCCP measured by the LED-P were significantly influenced. An in vivo validation experiment was undertaken to measure renal cortical Po2 in a rat subjected to hypoxic ventilation conditions and ischemia/reperfusion. The benefits of using LEDs as a light excitation source are presented.

Ivabradine Attenuates the Microcirculatory Derangements Evoked by Experimental Sepsis

Background

Experimental data suggest that ivabradine, an inhibitor of the pacemaker current in sinoatrial node, exerts beneficial effects on endothelial cell function, but it is unclear if this drug could prevent microcirculatory dysfunction in septic subjects, improving tissue perfusion and reducing organ failure. Therefore, this study was designed to characterize the microcirculatory effects of ivabradine on a murine model of abdominal sepsis using intravital videomicroscopy.

Methods

Twenty-eight golden Syrian hamsters were allocated in four groups: sham-operated animals, nontreated septic animals, septic animals treated with saline, and septic animals treated with ivabradine (2.0 mg/kg intravenous bolus + 0.5 mg · kg−1 · h−1). The primary endpoint was the effect of ivabradine on the microcirculation of skinfold chamber preparations, assessed by changes in microvascular reactivity and rheologic variables, and the secondary endpoint was its effects on organ function, evaluated by differences in arterial blood pressure, motor activity score, arterial blood gases, and hematologic and biochemical parameters among groups.

Results

Compared with septic animals treated with saline, those treated with ivabradine had greater functional capillary density (90 ± 4% of baseline values vs. 71 ± 16%; P &lt; 0.001), erythrocyte velocity in capillaries (87 ± 11% of baseline values vs. 62 ± 14%; P &lt; 0.001), and arteriolar diameter (99 ± 4% of baseline values vs. 91 ± 7%; P = 0.041) at the end of the experiment. Besides that, ivabradine-treated animals had less renal, hepatic, and neurologic dysfunction.

Conclusions

Ivabradine was effective in reducing microvascular derangements evoked by experimental sepsis, which was accompanied by less organ dysfunction. These results suggest that ivabradine yields beneficial effects on the microcirculation of septic animals.

THE ENDOTHELIUM IN SEPSIS

Sepsis affects practically all aspects of endothelial cell (EC) function and is thought to be the key factor in the progression from sepsis to organ failure. Endothelial functions affected by sepsis include vasoregulation, barrier function, inflammation, and hemostasis. These are among other mechanisms often mediated by glycocalyx shedding, such as abnormal nitric oxide metabolism, up-regulation of reactive oxygen species generation due to down-regulation of endothelial-associated antioxidant defenses, transcellular communication, proteases, exposure of adhesion molecules, and activation of tissue factor. This review covers current insight in EC-associated hemostatic responses to sepsis and the EC response to inflammation. The endothelial cell lining is highly heterogeneous between different organ systems and consequently also in its response to sepsis. In this context, we discuss the response of the endothelial cell lining to sepsis in the kidney, liver, and lung. Finally, we discuss evidence as to whether the EC response to sepsis is adaptive or maladaptive. This study is a result of an Acute Dialysis Quality Initiative XIV Sepsis Workgroup meeting held in Bogota, Columbia, between October 12 and 15, 2014.

Haemodynamic coherence - The relevance of fluid therapy

The ultimate goal of fluid therapy is to improve the oxygenation of cells by improving the cardiac output, thus improving microcirculation by optimizing macrocirculation. This haemodynamic coherence is often altered in patients with haemorrhagic shock and sepsis. The loss of haemodynamic coherence is associated with adverse outcomes. It may be influenced by the mechanisms of the underlying disease and properties of different fluids used for resuscitation in these critically ill patients. Monitoring microcirculation and haemodynamic coherence may be an additional tool to predict the response to fluid administration. In addition, microcirculatory analysis may support the clinician in his decision to not administer fluids when microcirculatory blood flow is preserved. In future, the indication, guidance and termination of fluid therapy may be assessed by bedside microvascular analysis in combination with standard haemodynamic monitoring.

Plasma-Lyte 148: A clinical review

AIM

To outline the physiochemical properties and specific clinical uses of Plasma-Lyte 148 as choice of solution for fluid intervention in critical illness, surgery and perioperative medicine.

METHODS

We performed an electronic literature search from Medline and PubMed (via Ovid), anesthesia and pharmacology textbooks, and online sources including studies that compared Plasma-Lyte 148 to other crystalloid solutions. The following keywords were used: “surgery”, “anaesthesia”, “anesthesia”, “anesthesiology”, “anaesthesiology”, “fluids”, “fluid therapy”, “crystalloid”, “saline”, “plasma-Lyte”, “plasmalyte”, “hartmann’s”, “ringers”“acetate”, “gluconate”, “malate”, “lactate”. All relevant articles were accessed in full. We summarized the data and reported the data in tables and text.

RESULTS

We retrieved 104 articles relevant to the choice of Plasma-Lyte 148 for fluid intervention in critical illness, surgery and perioperative medicine. We analyzed the data and reported the results in tables and text.

CONCLUSION

Plasma-Lyte 148 is an isotonic, buffered intravenous crystalloid solution with a physiochemical composition that closely reflects human plasma. Emerging data supports the use of buffered crystalloid solutions in preference to saline in improving physicochemical outcomes. Further large randomized controlled trials assessing the comparative effectiveness of Plasma-Lyte 148 and other crystalloid solutions in measuring clinically important outcomes such as morbidity and mortality are needed.

Hyperchloremia and moderate increase in serum chloride are associated with acute kidney injury in severe sepsis and septic shock patients

Background

Acute kidney injury and hyperchloremia are commonly present in critically ill septic patients. Our study goal was to evaluate the association of hyperchloremia and acute kidney injury in severe sepsis and septic shock patients.

Methods

In this retrospective cohort study in a provincial tertiary care hospital, adult patients with severe sepsis or septic shock and serum chloride measurements were included. Serum chloride was measured on a daily basis for 48 hours. Primary outcome was development of acute kidney injury (AKI) and association of AKI and serum chloride parameters was analyzed.

Results

A total of 240 patients were included in the study, 98 patients (40.8 %) had hyperchloremia. The incidence of acute kidney injury (AKI) was significantly higher in the hyperchloremia group (85.7 % vs 47.9 %; p < 0.001). Maximal chloride concentration in the first 48 hours ([Cl^-]_max) was significantly associated with AKI. In multivariate analysis, [Cl^-]_max was independently associated with AKI [adjusted odds ratio (OR) for AKI = 1.28 (1.02–1.62); p = 0.037]. The increase in serum chloride (Δ[Cl^-] = [Cl^-]_max – initial chloride concentration) demonstrated a dose-dependent relationship with severity of AKI. The mean Δ[Cl^-] in patients without AKI was 2.1 mmol/L while in the patients with AKI stage 1, 2 and 3 the mean Δ[Cl^-] was 5.1, 5.9 and 6.7 mmol/L, respectively. A moderate increase in serum chloride (Δ[Cl^-] ≥ 5 mmol/L) was associated with AKI [OR = 5.70 (3.00–10.82); p < 0.001], even in patients without hyperchloremia [OR = 8.25 (3.44–19.78); p < 0.001].

Conclusions

Hyperchloremia is common in severe sepsis and septic shock and independently associated with AKI. A moderate increase in serum chloride (Δ[Cl^-] ≥5 mmol/L) is associated with AKI even in patients without hyperchloremia.

Effects of Different Crystalloid Solutions on Hemodynamics, Peripheral Perfusion, and the Microcirculation in Experimental Abdominal Sepsis

BACKGROUND

Crystalloid solutions are used to restore intravascular volume in septic patients, but each solution has limitations. The authors compared the effects of three crystalloid solutions on hemodynamics, organ function, microcirculation, and survival in a sepsis model.

METHODS

Peritonitis was induced by injection of autologous feces in 21 anesthetized, mechanically ventilated adult sheep. After baseline measurements, animals were randomized to lactated Ringer's (LR), normal saline (NS), or PlasmaLyte as resuscitation fluid. The sublingual microcirculation was assessed using sidestream dark field videomicroscopy and muscle tissue oxygen saturation with near-infrared spectroscopy.

RESULTS

NS administration was associated with hyperchloremic acidosis. NS-treated animals had lower cardiac index and left ventricular stroke work index than LR-treated animals from 8 h and lower mean arterial pressure than LR-treated animals from 12 h. NS-treated animals had a lower proportion of perfused vessels than LR-treated animals after 12 h (median, 82 [71 to 83] vs. 85 [82 to 89], P = 0.04) and greater heterogeneity of proportion of perfused vessels than PlasmaLyte or LR groups at 18 h. Muscle tissue oxygen saturation was lower at 16 h in the NS group than in the other groups. The survival time of NS-treated animals was shorter than that of the LR group (17 [14 to 20] vs. 26 [23 to 29] h, P < 0.01) but similar to that of the PlasmaLyte group (20 [12 to 28] h, P = 0.74).

CONCLUSIONS

In this abdominal sepsis model, resuscitation with NS was associated with hyperchloremic acidosis, greater hemodynamic instability, a more altered microcirculation, and more severe organ dysfunction than with balanced fluids. Survival time was shorter than in the LR group.

Effects of N-acetylcysteine (NAC) supplementation in resuscitation fluids on renal microcirculatory oxygenation, inflammation, and function in a rat model of endotoxemia

Background

Modulation of inflammation and oxidative stress appears to limit sepsis-induced damage in experimental models. The kidney is one of the most sensitive organs to injury during septic shock. In this study, we evaluated the effect of N-acetylcysteine (NAC) administration in conjunction with fluid resuscitation on renal oxygenation and function. We hypothesized that reducing inflammation would improve the microcirculatory oxygenation in the kidney and limit the onset of acute kidney injury (AKI).

Methods

Rats were randomized into five groups (n = 8 per group): (1) control group, (2) control + NAC, (3) endotoxemic shock with lipopolysaccharide (LPS) without fluids, (4) LPS + fluid resuscitation, and (5) LPS + fluid resuscitation + NAC (150 mg/kg/h). Fluid resuscitation was initiated at 120 min and maintained at fixed volume for 2 h with hydroxyethyl starch (HES 130/0.4) dissolved in acetate-balanced Ringer’s solution (Volulyte) with or without supplementation with NAC (150 mg/kg/h). Oxygen tension in the renal cortex (CμPO₂), outer medulla (MμPO₂), and renal vein was measured using phosphorimetry. Biomarkers of renal injury, inflammation, and oxidative stress were assessed in kidney tissues.

Results

Fluid resuscitation significantly improved the systemic and renal macrohemodynamic parameters after LPS. However, the addition of NAC further improved cortical renal oxygenation, oxygen delivery, and oxygen consumption (p < 0.05). NAC supplementation dampened the accumulation of NGAL or L-FABP, hyaluronic acid, and nitric oxide in kidney tissue (p < 0.01).

Conclusion

The addition of NAC to fluid resuscitation may improve renal oxygenation and attenuate microvascular dysfunction and AKI. Decreases in renal NO and hyaluronic acid levels may be involved in this beneficial effect. A therapeutic strategy combining initial fluid resuscitation with antioxidant therapies may prevent sepsis-induced AKI.

Plasma syndecan-1 and heparan sulfate correlate with microvascular glycocalyx degradation in hemorrhaged rats after different resuscitation fluids

The endothelial glycocalyx plays an essential role in many physiological functions and is damaged after hemorrhage. Fluid resuscitation may further change the glycocalyx after an initial hemorrhage-induced degradation. Plasma levels of syndecan-1 and heparan sulfate have been used as indirect markers for glycocalyx degradation, but the extent to which these measures are representative of the events in the microcirculation is unknown. Using hemorrhage and a wide range of resuscitation fluids, we studied quantitatively the relationship between plasma biomarkers and changes in microvascular parameters, including glycocalyx thickness. Rats were bled 40% of total blood volume and resuscitated with seven different fluids (fresh whole blood, blood products, and crystalloids). Intravital microscopy was used to estimate glycocalyx thickness in >270 postcapillary venules from 58 cremaster preparations in 9 animal groups; other microvascular parameters were measured using noninvasive techniques. Systemic physiological parameters and blood chemistry were simultaneously collected. Changes in glycocalyx thickness were negatively correlated with changes in plasma levels of syndecan-1 ( r = −0.937) and heparan sulfate ( r = −0.864). Changes in microvascular permeability were positively correlated with changes in both plasma biomarkers ( r = 0.8, P < 0.05). Syndecan-1 and heparan sulfate were also positively correlated ( r = 0.7, P < 0.05). Except for diameter and permeability, changes in local microcirculatory parameters (red blood cell velocity, blood flow, and wall shear rate) did not correlate with plasma biomarkers or glycocalyx thickness changes. This work provides a quantitative framework supporting plasma syndecan-1 and heparan sulfate as valuable clinical biomarkers of glycocalyx shedding that may be useful in guiding resuscitation strategies following hemorrhage.

Resveratrol Rescues Kidney Mitochondrial Function Following Hemorrhagic Shock

OBJECTIVE

Hemorrhagic shock may contribute to acute kidney injury (AKI) by profoundly altering renal mitochondrial function. Resveratrol (RSV), a naturally occurring sirtuin 1 (SIRT1) activator, has been shown to promote mitochondrial function and reduce oxidative damage in a variety of aging-related disease states. We hypothesized that RSV treatment during resuscitation would ameliorate kidney mitochondrial dysfunction and decrease oxidative damage following hemorrhagic shock.

METHODS

Using a decompensated hemorrhagic shock model, male Long-Evans rats (n = 6 per group) were killed prior to hemorrhage (sham), at severe shock, and following either lactated Ringer's (LR) resuscitation or LR + RSV resuscitation (RSV: 30 mg/kg). At each time point, blood samples were assayed for arterial blood gases, lactate, blood urea nitrogen, and serum creatinine. Mitochondria were also isolated from kidney samples in order to assess individual electron transport complexes (complexes I, II, and IV) using high-resolution respirometry. Total mitochondria reactive oxygen species were measured using fluorometry, and lipid peroxidation was assessed by measuring 4-hydroxynonenal by Western blot. Quantitative polymerase chain reaction was used quantify mRNA from peroxisome proliferator-activated receptor γ coactivator 1-α (PGC1-α) SIRT1, and proteins known to mitigate oxidative damage and promote mitochondrial biogenesis.

RESULTS

Resveratrol supplementation during resuscitation restored mitochondrial respiratory capacity and decreased mitochondrial reactive oxygen species and lipid peroxidation. Compared with standard LR resuscitation, RSV treatment significantly increased SIRT1 and PGC1-α expression and significantly increased both superoxide dismutase 2 and catalase expression. Although RSV was associated with decreased lactate production, pH, blood urea nitrogen, and serum creatinine values did not differ between resuscitation strategies.

CONCLUSIONS

Resuscitation with RSV significantly restored renal mitochondrial function and decreased oxidative damage following hemorrhagic shock.

Impact of common crystalloid solutions on resuscitation markers following Class I hemorrhage: A randomized control trial

BACKGROUND

Resuscitation after hemorrhage with crystalloid solutions can lead to marked acidosis and iatrogenically worsen the lethal triad. The effect of differing solutions on base deficit and lactate has been sparsely prospectively studied in humans. We sought to quantify the effect of normal saline (NS) and lactated Ringer's (LR) resuscitation in voluntary blood donors as a model for Class I hemorrhage.

METHODS

A prospective randomized control trial was conducted in conjunction with blood drives. Donors were randomized to receive no intravenous fluid (noIVF), 2-L NS, or 2-L LR after blood donation of 500 mL. Lactate and base deficit were measured before and after fluid administration using an iSTAT. The mean laboratory values were compared between groups first using a global test followed by pairwise testing between groups using the Wilcoxon rank-sum and Kruskal-Wallis tests. The Bonferroni correction was used and a statistical significance of p < 0.0167 was set.

RESULTS

A total of 157 patients completed the study. The mean (SD) age was 39.2 (12.7), and 65.0% were female. Patients in each group lost equivalent amounts of total blood volume, and a similar amount was replaced in the crystalloid group (p > 0.0167). Donors had comparable increases in lactate and base deficit after donation regardless of the group (p > 0.0167). After resuscitation with 2-L crystalloid, the lactate level increased higher in the LR group than in the noIVF or the NS group (1.36 mmol/L vs. 1.00 mmol/L vs. 1.54 mmol/L, p < 0.0001). In addition, the resuscitation base deficit increased in the NS group more than in the noIVF or LR group (-0.65 vs. -3.06 vs. -0.34, p < 0.0001).

CONCLUSION

This study is one of the first human studies to prospectively demonstrate quantifiable differences in base deficit and lactate by type of crystalloid resuscitation. LR resuscitation elevated lactate levels, and NS negatively affected the base deficit. These findings are critical to the interpretation of trauma patient resuscitation with crystalloid solutions.

LEVEL OF EVIDENCE

Therapeutic study, level II.

Prehospital volume resuscitation--Did evidence defeat the crystalloid dogma? An analysis of the TraumaRegister DGU® 2002-2012

Background

Various studies have shown the deleterious effect of high volume resuscitation following severe trauma promoting coagulopathy by haemodilution, acidosis and hypothermia. As the optimal resuscitation strategy during prehospital trauma care is still discussed, we raised the question if the amount and kind of fluids administered changed over the recent years. Further, if less volume was administered, fewer patients should have arrived in coagulopathic depletion in the Emergency Department resulting in less blood product transfusions.

Methods

A data analysis of the 100 489 patients entered into the TraumaRegister DGU® (TR-DGU) between 2002 and 2012 was performed of which a total of 23512 patients (23.3 %) matched the inclusion criteria. Volume and type of fluids administered as well as outcome parameter were analysed.

Results

Between 2002 and 2012, the amount of volume administered during prehospital trauma care decreased from 1790 ml in 2002 to 1039 ml in 2012. At the same time higher haemoglobin mean values, higher Quick’s mean values and reduced mean aPTT can be observed. Simultaneously, more patients received catecholamines (2002: 9.2 to 2012: 13.0 %). Interestingly, the amount of volume administered decreased steadily regardless of the presence of shock. Fewer patients were in the need of blood products and the number of massive transfusions (≥10 pRBC) more than halved.

Discussion

The changes in volume therapy might have reduced haemodilution potentially resulting in an increase of the Hb value. During the period observed transfusion strategies have become more restrictiveand ratio based; the percentage of patients receiving MT halved as blood products may imply negative secondary effects. Furthermore, preventing administration of high blood product ratios result in less impairment of coagulation factors and inhibitors and an therfore improved coagulation.

Conclusion

The volume administered in severely injured patients decreased considerably during the last decade possibly supporting beneficial effects such as minimizing the risk of coagulopathy and avoiding potential harmful effects caused by blood product transfusions. Despite outstanding questions in trauma resuscitation, principle evidence merges quickly into clinical practice and algorithms.

New perspectives of volemic resuscitation in polytrauma patients: a review

Nowadays, fluid resuscitation of multiple trauma patients is still a challenging therapy. Existing therapies for volume replacement in severe haemorrhagic shock can lead to adverse reactions that may be fatal for the patient. Patients presenting with multiple trauma often develop hemorrhagic shock, which triggers a series of metabolic, physiological and cellular dysfunction. These disorders combined, lead to complications that significantly decrease survival rate in this subset of patients. Volume and electrolyte resuscitation is challenging due to many factors that overlap. Poor management can lead to post-resuscitation systemic inflammation causing multiple organ failure and ultimately death. In literature, there is no exact formula for this purpose, and opinions are divided. This paper presents a review of modern techniques and current studies regarding the management of fluid resuscitation in trauma patients with hemorrhagic shock. According to the literature and from clinical experience, all aspects regarding post-resuscitation period need to be considered. Also, for every case in particular, emergency therapy management needs to be rigorously respected considering all physiological, biochemical and biological parameters.

Does saline resuscitation affect mechanisms of coagulopathy in critically ill trauma patients? An exploratory analysis

Metabolic acidosis has been implicated in the development of coagulopathy, although the specific mechanisms have not been well characterized. We sought to explore whether resuscitation of injured patients with a balanced crystalloid solution affects coagulation, as measured by endogenous thrombin potential (ETP) and thromboelastography (TEG). We performed an exploratory analysis of a subset of subjects enrolled in a randomized trial comparing the effect of resuscitation with isotonic saline versus Plasma-Lyte A (PLA) on acidosis and electrolyte abnormalities. We collected plasma at admission and 6 h later for subsequent ETP and TEG analysis and compared subjects receiving isotonic saline to those receiving PLA. Among 18 evaluated subjects, baseline characteristics, including ETP and TEG parameters, were similar between the two arms. At 6 h, subjects receiving isotonic saline were more acidemic. At 6 h, there were no differences in ETP parameters between groups; however, TEG results showed the time from initial clot formation to an amplitude of 20 mm (K) was shorter (3.8 ± 2.1 vs. 7.2 ± 2.8 s) and the rapidity of fibrin build-up and cross-linking (α angle) was significantly greater (41 ± 8 vs. 24 ± 15 deg) for the PLA group than in the isotonic saline group. Relative to PLA, isotonic saline does not alter thrombin generation, but isotonic saline and PLA may differentially impact clotting factor availability. The shorter time to reach prespecified clot amplitude and the increased rate of fibrin generation imply faster amplification of clotting factors with PLA without effect on latency time or clot strength.