Conservative vs liberal fluid therapy in septic shock (CLASSIC) trial-Protocol and statistical analysis plan

Effects of IV fluid restriction according to site-specific intensity of standard fluid treatment-protocol

BACKGROUND

Variation in usual practice in fluid trials assessing lower versus higher volumes may affect overall comparisons. To address this, we will evaluate the effects of heterogeneity in treatment intensity in the Conservative versus Liberal Approach to Fluid Therapy of Septic Shock in Intensive Care trial. This will reflect the effects of differences in site-specific intensities of standard fluid treatment due to local practice preferences while considering participant characteristics.

METHODS

We will assess the effects of heterogeneity in treatment intensity across one primary (all-cause mortality) and three secondary outcomes (serious adverse events or reactions, days alive without life support and days alive out of hospital) after 90 days. We will classify sites based on the site-specific intensity of standard fluid treatment, defined as the mean differences in observed versus predicted intravenous fluid volumes in the first 24 h in the standard-fluid group while accounting for differences in participant characteristics. Predictions will be made using a machine learning model including 22 baseline predictors using the extreme gradient boosting algorithm. Subsequently, sites will be grouped into fluid treatment intensity subgroups containing at least 100 participants each. Subgroups differences will be assessed using hierarchical Bayesian regression models with weakly informative priors. We will present the full posterior distributions of relative (risk ratios and ratios of means) and absolute differences (risk differences and mean differences) in each subgroup.

DISCUSSION

This study will provide data on the effects of heterogeneity in treatment intensity while accounting for patient characteristics in critically ill adult patients with septic shock.

REGISTRATIONS

The European Clinical Trials Database (EudraCT): 2018-000404-42, ClinicalTrials. gov: NCT03668236.

Effects of restrictive fluid therapy on the time to resolution of hyperlactatemia in ICU patients with septic shock. A secondary post hoc analysis of the CLASSIC randomized trial

PURPOSE

The aim of this study was to examine the effects of intravenous (IV) fluid restriction on time to resolution of hyperlactatemia in septic shock. Hyperlactatemia in sepsis is associated with worse outcome. Sepsis guidelines suggest targeting lactate clearance to guide fluid therapy despite the complexity of hyperlactatemia and the potential harm of fluid overload.

METHODS

We conducted a post hoc analysis of serial plasma lactate concentrations in a sub-cohort of 777 patients from the international multicenter clinical CLASSIC trial (restriction of intravenous fluids in intensive care unit (ICU) patients with septic shock). Adult ICU patients with septic shock had been randomized to restrictive (n = 385) or standard (n = 392) intravenous fluid therapy. The primary outcome, time to resolution of hyperlactatemia, was analyzed with a competing-risks regression model. Death and discharge were competing outcomes, and administrative censoring was imposed 72 h after randomization if hyperlactatemia persisted. The regression analysis was adjusted for the same stratification variables and covariates as in the original CLASSIC trial analysis.

RESULTS

The hazard ratios (HRs) for the cumulative probability of resolution of hyperlactatemia, in the restrictive vs the standard group, in the unadjusted analysis, with time split, were 0.94 (confidence interval (CI) 0.78-1.14) at day 1 and 1.21 (0.89-1.65) at day 2-3. The adjusted analyses were consistent with the unadjusted results.

CONCLUSION

In this post hoc retrospective analysis of a multicenter randomized controlled trial (RCT), a restrictive intravenous fluid strategy did not seem to affect the time to resolution of hyperlactatemia in adult ICU patients with septic shock.

Albumin use in patients with septic shock-Post-hoc analyses of an international randomised fluid trial

BACKGROUND

Albumin administration is suggested in patients with sepsis and septic shock who have received large volumes of crystalloids. Given lack of firm evidence, clinical practice variation may exist. To address this, we investigated if patient characteristics or trial site were associated with albumin use in septic shock.

METHODS

We conducted a post-hoc study of the CLASSIC international, randomised clinical trial of fluid volumes in septic shock. Associations between selected baseline variables and trial site with albumin use during ICU stay were assessed in Cox models considering death, ICU discharge, and loss-to-follow-up as competing events. Baseline variables were first assessed individually, adjusted for treatment allocation (restrictive vs. standard IV fluid), and then adjusted for allocation and the other baseline variables. Site was assessed in a model adjusted for allocation and baseline variables.

RESULTS

We analysed 1541 of 1554 patients randomised in CLASSIC (99.2%). During ICU stay, 36.3% of patients in the restrictive-fluid group and 52.6% in the standard-fluid group received albumin. Gastrointestinal focus of infection and higher doses of norepinephrine were most strongly associated with albumin use (subgroup with highest quartile of norepinephrine doses, hazard ratio (HR) 2.58, 95% CI 1.89 to 3.53). HRs for associations between site and albumin use ranged from 0.11 (95% CI 0.05 to 0.26) to 1.70 (95% CI 1.06 to 2.74); test for overall effect of site: p < .001.

CONCLUSIONS

In adults with septic shock, gastrointestinal focus of infection and higher doses of norepinephrine at baseline were associated with albumin use, which also varied substantially between sites.

Restrictive versus standard IV fluid therapy in adult ICU patients with septic shock-Bayesian analyses of the CLASSIC trial

BACKGROUND

The CLASSIC trial assessed the effects of restrictive versus standard intravenous (IV) fluid therapy in adult intensive care unit (ICU) patients with septic shock. This pre-planned study provides a probabilistic interpretation and evaluates heterogeneity in treatment effects (HTE).

METHODS

We analysed mortality, serious adverse events (SAEs), serious adverse reactions (SARs) and days alive without life-support within 90 days using Bayesian models with weakly informative priors. HTE on mortality was assessed according to five baseline variables: disease severity, vasopressor dose, lactate levels, creatinine values and IV fluid volumes given before randomisation.

RESULTS

The absolute difference in mortality was 0.2%-points (95% credible interval: -5.0 to 5.4; 47% posterior probability of benefit [risk difference <0.0%-points]) with restrictive IV fluid. The posterior probabilities of benefits with restrictive IV fluid were 72% for SAEs, 52% for SARs and 61% for days alive without life-support. The posterior probabilities of no clinically important differences (absolute risk difference ≤2%-points) between the groups were 56% for mortality, 49% for SAEs, 90% for SARs and 38% for days alive without life-support. There was 97% probability of HTE for previous IV fluid volumes analysed continuously, that is, potentially relatively lower mortality of restrictive IV fluids with higher previous IV fluids. No substantial evidence of HTE was found in the other analyses.

CONCLUSION

We could not rule out clinically important effects of restrictive IV fluid therapy on mortality, SAEs or days alive without life-support, but substantial effects on SARs were unlikely. IV fluids given before randomisation might interact with IV fluid strategy.

Albumin administration in septic shock-Protocol for post-hoc analyses of data from a multicentre RCT

BACKGROUND

Intravenous (IV) albumin is suggested for patients with septic shock who have received large amounts of IV crystalloids; a conditional recommendation based on moderate certainty of evidence. Clinical variation in the administration of IV albumin in septic shock may exist according to patient characteristics and location.

METHODS

This is a protocol and statistical analysis plan for a post-hoc secondary study of the Conservative versus Liberal Approach to Fluid Therapy of Septic Shock in Intensive Care (CLASSIC) RCT of 1554 adult ICU patients with septic shock. We will assess if specific baseline characteristics or trial site are associated with the administration of IV albumin during ICU stay using Cox models with competing events. All models will be adjusted for the treatment allocation in CLASSIC (restrictive vs. standard IV fluid), and all analyses will consider competing events (death, ICU discharge and loss-to-follow-up). We will present results as hazard ratios with 95% confidence intervals and p-values for the associations of baseline characteristics or site with IV albumin administration. Between-group differences (interactions) will be assessed using p-values from likelihood ratio tests. All results will be considered exploratory only.

DISCUSSION

This secondary study of the CLASSIC RCT may yield important insight into potential practice variation in the administration of albumin in septic shock.

Long-term effects of restriction of intravenous fluid in adult ICU patients with septic shock

PURPOSE

To assess long-term outcomes of restrictive versus standard intravenous (IV) fluid therapy in adult intensive care unit (ICU) patients with septic shock included in the European Conservative versus Liberal Approach to Fluid Therapy in Septic Shock in Intensive Care (CLASSIC) trial.

METHODS

We conducted the pre-planned analyses of mortality, health-related quality of life (HRQoL) using EuroQol (EQ)-5D-5L index values and EQ visual analogue scale (VAS), and cognitive function using Mini Montreal Cognitive Assessment (Mini MoCA) test at 1 year. Deceased patients were assigned numerical zero for HRQoL as a state equal to death and zero for cognitive function outcomes as worst possible score, and we used multiple imputation for missing data on HRQoL and cognitive function.

RESULTS

Among 1554 randomized patients, we obtained 1-year data on mortality in 97.9% of patients, HRQoL in 91.3%, and cognitive function in 86.3%. One-year mortality was 385/746 (51.3%) in the restrictive-fluid group versus 383/767 (49.9%) in the standard-fluid group, absolute risk difference 1.5%-points [99% confidence interval (CI) - 4.8 to 7.8]. Mean differences were 0.00 (99% CI - 0.06 to 0.05) for EQ-5D-5L index values, - 0.65 for EQ VAS (- 5.40 to 4.08), and - 0.14 for Mini MoCA (- 1.59 to 1.14) for the restrictive-fluid group versus the standard-fluid group. The results for survivors only were similar in both groups.

CONCLUSIONS

Among adult ICU patients with septic shock, restrictive versus standard IV fluid therapy resulted in similar survival, HRQoL, and cognitive function at 1 year, but clinically important differences could not be ruled out.

Active fluid de-resuscitation in critically ill patients with septic shock: A systematic review and meta-analysis

PURPOSE

To evaluate the impact of active fluid de-resuscitation on mortality in critically ill patients with septic shock.

METHODS

A systematic search was performed on PubMed, EmBase, and the Cochrane Library databases. Trials investigating active fluid de-resuscitation and reporting data on mortality in patients with septic shock were eligible. The primary objective was the impact of active de-resuscitation in patients with septic shock on short-term mortality. Secondary outcomes were whether de-resuscitation lead to a fluid separation, and the impact of de-resuscitation on patient-centred outcomes.

RESULTS

Thirteen trials (8,030 patients) were included in the systematic review, whereof 5 randomised-controlled trials (RCTs) were included in the meta-analysis. None of the RCTs showed a reduction in mortality with active de-resuscitation measures (relative risk (RR) 1.12 [95%-CI 0.84 - 1.48]). Fluid separation was achieved by two RCTs. Evidence from non-randomised trials suggests a mortality benefit with de-resuscitation strategies and indicates a trend towards a more negative fluid balance. Patient-centred outcomes were not influenced in the RCTs, and only one non-randomised trial revealed an impact on the duration of mechanical ventilation and renal replacement requirement (RRT).

CONCLUSION

We found no evidence for superiority of active fluid de-resuscitation compared to usual care regarding mortality, fluid balance or patient-centred outcomes in patients with septic shock. Current evidence is limited by the lack of high-quality RCTs in patients with septic shock, the small sample sizes and the heterogeneity of the applied de-resuscitation techniques. In addition, validity of the majority of RCTs is compromised by their inability to achieve fluid separation.

Effects of Fluids on the Sublingual Microcirculation in Sepsis

Sepsis is one of the most common and deadly syndromes faced in Intensive Care settings globally. Recent advances in bedside imaging have defined the changes in the microcirculation in sepsis. One of the most advocated interventions for sepsis is fluid therapy. Whether or not fluid bolus affects the microcirculation in sepsis has not been fully addressed in the literature. This systematic review of the evidence aims to collate studies examining the microcirculatory outcomes after a fluid bolus in patients with sepsis. We will assimilate the evidence for using handheld intra vital microscopes to guide fluid resuscitation and the effect of fluid bolus on the sublingual microcirculation in patients with sepsis and septic shock. We conducted a systematic search of Embase, CENTRAL and Medline (PubMed) using combinations of the terms "microcirculation" AND "fluid" OR "fluid resuscitation" OR "fluid bolus" AND "sepsis" OR "septic shock". We found 3376 potentially relevant studies. Fifteen studies published between 2007 and 2021 fulfilled eligibility criteria to be included in analysis. The total number of participants was 813; we included six randomized controlled trials and nine non-randomized, prospective observational studies. Ninety percent used Sidestream Dark Field microscopy to examine the microcirculation and 50% used Hydroxyethyl Starch as their resuscitation fluid. There were no clear effects of fluid on the microcirculation parameters. There was too much heterogeneity between studies and methodology to perform meta-analysis. Studies identified heterogeneity of affect in the sepsis population, which could mean that current clinical classifications were not able to identify different microcirculation characteristics. Use of microcirculation as a clinical endpoint in sepsis could help to define sepsis phenotypes. More research into the effects of different resuscitation fluids on the microcirculation is needed.

Endothelial Damage and the Microcirculation in Critical Illness

Endothelial integrity maintains microcirculatory flow and tissue oxygen delivery. The endothelial glycocalyx is involved in cell signalling, coagulation and inflammation. Our ability to treat critically ill and septic patients effectively is determined by understanding the underpinning biological mechanisms. Many mechanisms govern the development of sepsis and many large trials for new treatments have failed to show a benefit. Endothelial dysfunction is possibly one of these biological mechanisms. Glycocalyx damage is measured biochemically. Novel microscopy techniques now mean the glycocalyx can be indirectly visualised, using sidestream dark field imaging. How the clinical visualisation of microcirculation changes relate to biochemical laboratory measurements of glycocalyx damage is not clear. This article reviews the evidence for a relationship between clinically evaluable microcirculation and biological signal of glycocalyx disruption in various diseases in ICU. Microcirculation changes relate to biochemical evidence of glycocalyx damage in some disease states, but results are highly variable. Better understanding and larger studies of this relationship could improve phenotyping and personalised medicine in the future. Damage to the glycocalyx could underpin many critical illness pathologies and having real-time information on the glycocalyx and microcirculation in the future could improve patient stratification, diagnosis and treatment.

Fluid management of emergency department patients with sepsis-A survey of fluid resuscitation practices

BACKGROUND

Fluid administration and resuscitation of patients with sepsis admitted through emergency departments (ED) remains a challenge, and evidence is sparse especially in sepsis patients without shock. We aimed to investigate emergency medicine physicians' and nurses' perceptions, self-reported decision-making and daily behavior, and challenges in fluid administration of ED sepsis patients.

METHODS

We developed and conducted a multicenter, web-based, cross-sectional survey focusing on fluid administration to ED patients with sepsis sent to all nurses and physicians from the five EDs in the Central Denmark Region. The survey consisted of three sections: (1) baseline information; (2) perceptions of fluid administration and daily practice; and (3) clinical scenarios about fluid administration. The survey was performed from February to June, 2021.

RESULTS

In total, 138 of 246 physicians (56%) and 382 of 595 nurses (64%) responded to the survey. Of total, 94% of physicians and 97% of nurses regarded fluid as an important part of sepsis treatment. Of total, 80% of physicians and 61% of nurses faced challenges regarding fluid administration in the ED, and decisions were usually based on clinical judgment. The most common challenge was the lack of guidelines for fluid administration. Of total, 96% agreed that they would like to learn more about fluid administration, and 53% requested research in fluid administration of patients with sepsis. For a normotensive patient with sepsis, 46% of physicians and 44% of nurses administered 1000 ml fluid in the first hour. Of total, 95% of physicians and 89% of nurses preferred to administer ≥1000 ml within an hour if the patients' blood pressure was 95/60 at admission. There was marked variability in responses. Blood pressure was the most commonly used trigger for fluid administration. Respondents preferred to administer less fluid if the patient in the scenario had known renal impairment or heart failure. Normal saline was the preferred fluid.

CONCLUSION

Fluid administration is regarded as an important but challenging aspect of sepsis management. Responses to scenarios revealed variability in fluid volumes. Blood pressure was the most used trigger. ED nurses and physicians request evidence-based guidelines to improve fluid administration.

Restrictive fluids versus standard care in adults with sepsis in the emergency department (REFACED): A multicenter, randomized feasibility trial

BACKGROUND

Fluid treatment in sepsis is a challenge and clinical equipoise exists regarding intravenous (IV) volumes. We aimed to determine whether a 24-h protocol restricting IV fluid was feasible in adult patients with sepsis without shock presenting to the emergency department (ED).

METHODS

The REFACED Sepsis trial is an investigator-initiated, multicenter, randomized, open-label, feasibility trial, assigning sepsis patients without shock to 24 h of restrictive, crystal IV fluid administration or standard care. In the IV fluid restriction group fluid boluses were only permitted if predefined criteria for hypoperfusion occurred. Standard care was at the discretion of the treating team. The primary outcome was total IV crystalloid fluid volumes at 24 h after randomization. Secondary outcomes included total fluid volumes, feasibility measures, and patient-centered outcomes.

RESULTS

We included 123 patients (restrictive 61 patients and standard care 62 patients) in the primary analysis. A total of 32% (95% confidence interval [CI] 28%-37%) of eligible patients meeting all inclusion criteria and no exclusion criteria were included. At 24 h, the mean (±SD) IV crystalloid fluid volumes were 562 (±1076) ml versus 1370 (±1438) ml in the restrictive versus standard care group (mean difference -801 ml, 95% CI -1257 to -345 ml, p = 0.001). Protocol violations occurred in 21 (34%) patients in the fluid-restrictive group. There were no differences between groups in adverse events, use of mechanical ventilation or vasopressors, acute kidney failure, length of stay, or mortality.

CONCLUSIONS

A protocol restricting IV crystalloid fluids in ED patients with sepsis reduced 24-h fluid volumes compared to standard care. A future trial powered toward patient-centered outcomes appears feasible.

Fluid Management, Intra-Abdominal Hypertension and the Abdominal Compartment Syndrome: A Narrative Review

BACKGROUND

General pathophysiological mechanisms regarding associations between fluid administration and intra-abdominal hypertension (IAH) are evident, but specific effects of type, amount, and timing of fluids are less clear.

OBJECTIVES

This review aims to summarize current knowledge on associations between fluid administration and intra-abdominal pressure (IAP) and fluid management in patients at risk of intra-abdominal hypertension and abdominal compartment syndrome (ACS).

METHODS

We performed a structured literature search from 1950 until May 2021 to identify evidence of associations between fluid management and intra-abdominal pressure not limited to any specific study or patient population. Findings were summarized based on the following information: general concepts of fluid management, physiology of fluid movement in patients with intra-abdominal hypertension, and data on associations between fluid administration and IAH.

RESULTS

We identified three randomized controlled trials (RCTs), 38 prospective observational studies, 29 retrospective studies, 18 case reports in adults, two observational studies and 10 case reports in children, and three animal studies that addressed associations between fluid administration and IAH. Associations between fluid resuscitation and IAH were confirmed in most studies. Fluid resuscitation contributes to the development of IAH. However, patients with IAH receive more fluids to manage the effect of IAH on other organ systems, thereby causing a vicious cycle. Timing and approach to de-resuscitation are of utmost importance, but clear indicators to guide this decision-making process are lacking. In selected cases, only surgical decompression of the abdomen can stop deterioration and prevent further morbidity and mortality.

CONCLUSIONS

Current evidence confirms an association between fluid resuscitation and secondary IAH, but optimal fluid management strategies for patients with IAH remain controversial.

Nursing Implications of the Updated 2021 Surviving Sepsis Campaign Guidelines

Sepsis is a life-threatening illness that affects millions of people worldwide. Early recognition and timely treatment are essential for decreasing mortality from sepsis. The Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2021, the fifth iteration of the guidelines, was released in October 2021 and includes 93 recommendations for the management of sepsis. The evidence-based guidelines include recommendations and rationales for screening and early treatment, initial resuscitation, mean arterial pressure targets, admission to intensive care, management of infection, hemodynamic monitoring, ventilation, and additional therapies. A new section addresses long-term outcomes and goals of care. This article presents several recommendations, changes, and updates in the 2021 guidelines and highlights the important contributions nurses have in delivering timely and evidence-based care to patients with sepsis. Recommendations may be for or against an intervention, according to the evidence. Although many recommendations are unchanged, several new recommendations directly affect nursing care and may require specialized training (eg, venovenous extracorporeal membrane oxygenation). The newest section, long-term outcomes and goals of care, is aimed at using available resources to provide care that is aligned with the patient and the patient's family through goals-of-care discussions and shared decision-making. Interventions aimed at improving recovery across the continuum of care should include attention to long-term outcomes. Nurses are essential in identifying patients with sepsis, administering and assessing response to treatment, supporting the patient and family, and limiting sequelae from sepsis. This article highlights the 2021 recommendations that influence nursing care for patients with sepsis.

Conservative vs. liberal fluid therapy in septic shock - Protocol for secondary Bayesian analyses of the CLASSIC trial

BACKGROUND

Clinical equipoise exists regarding intravenous (IV) fluid volumes in sepsis. The Conservative vs. Liberal Approach to fluid therapy of Septic Shock in Intensive Care (CLASSIC) trial investigates the effect of restricted vs. standard IV fluid therapy in 1554 adult intensive care unit patients with septic shock.

METHODS

This protocol describes secondary Bayesian analyses of the primary outcome (90-day all-cause mortality) and three secondary outcomes at day 90. We will analyse all binary outcomes with adjusted Bayesian logistic regressions and present results as conditional relative risks and risk differences with 95% credibility intervals (CrIs). The secondary count outcome will be analysed using adjusted Bayesian linear regression with results summarised as conditional mean differences and ratios of means with 95% Crls. We will use weakly informative priors for the primary analyses, and sceptical and evidence-based priors in the sensitivity analyses. Exact probabilities will be presented for any benefit/harm, clinically important benefit/harm and no clinically important difference. We will assess whether heterogeneity of treatment effects on mortality is present using Bayesian hierarchical models in subgroups and on the continuous scale using models with interactions according to five baseline variables assessing the overall severity of illness and the degree of circulatory and renal impairment.

DISCUSSION

The outlined analyses will supplement the primary analysis of the CLASSIC trial by describing probabilities of beneficial and harmful effects and evaluating heterogeneity of treatment effects in a framework that may be easier to interpret for researchers and clinicians.

Restriction of Intravenous Fluid in ICU Patients with Septic Shock

BACKGROUND

Intravenous fluids are recommended for the treatment of patients who are in septic shock, but higher fluid volumes have been associated with harm in patients who are in the intensive care unit (ICU).

METHODS

In this international, randomized trial, we assigned patients with septic shock in the ICU who had received at least 1 liter of intravenous fluid to receive restricted intravenous fluid or standard intravenous fluid therapy; patients were included if the onset of shock had been within 12 hours before screening. The primary outcome was death from any cause within 90 days after randomization.

RESULTS

We enrolled 1554 patients; 770 were assigned to the restrictive-fluid group and 784 to the standard-fluid group. Primary outcome data were available for 1545 patients (99.4%). In the ICU, the restrictive-fluid group received a median of 1798 ml of intravenous fluid (interquartile range, 500 to 4366); the standard-fluid group received a median of 3811 ml (interquartile range, 1861 to 6762). At 90 days, death had occurred in 323 of 764 patients (42.3%) in the restrictive-fluid group, as compared with 329 of 781 patients (42.1%) in the standard-fluid group (adjusted absolute difference, 0.1 percentage points; 95% confidence interval [CI], -4.7 to 4.9; P = 0.96). In the ICU, serious adverse events occurred at least once in 221 of 751 patients (29.4%) in the restrictive-fluid group and in 238 of 772 patients (30.8%) in the standard-fluid group (adjusted absolute difference, -1.7 percentage points; 99% CI, -7.7 to 4.3). At 90 days after randomization, the numbers of days alive without life support and days alive and out of the hospital were similar in the two groups.

CONCLUSIONS

Among adult patients with septic shock in the ICU, intravenous fluid restriction did not result in fewer deaths at 90 days than standard intravenous fluid therapy. (Funded by the Novo Nordisk Foundation and others; CLASSIC ClinicalTrials.gov number, NCT03668236.).

Public versus patient health preferences: protocol for a study to elicit EQ-5D-5L health state valuations for patients who have survived a stay in intensive care

INTRODUCTION

The value set used when calculating quality-adjusted life-years (QALYs) is most often based on stated preference data elicited from a representative sample of the general population. However, having a severe disease may alter a person's health preferences, which may imply that, for some patient groups, experienced QALYs may differ from those that are estimated via standard methods. This study aims to model 5-level EuroQol 5-dimensional questionnaire (EQ-5D-5L) valuations based on preferences elicited from a sample of patients who have survived a stay in a Danish intensive care unit (ICU) and to compare these with the preferences of the general population. Further, the heterogeneity in the ICU patients' preferences will be investigated.

METHODS AND ANALYSIS

This valuation study will elicit EQ-5D-5L health state preferences from a sample of 300 respondents enrolled in two randomised controlled trials at Danish ICUs. Patients' preferences will be elicited using composite time trade-off based on the EuroQol Valuation Technology, the same as that used to generate the EQ-5D-5L value set for the Danish general population. The patient-based and the public-based EQ-5D-5L valuations will be compared. Potential underlying determinants of the ICU preferences will be investigated through analyses of demographic characteristics, time since the ICU stay, self-reported health, willingness to trade-off length of life for quality of life, health state reference dependency and EQ-5D dimensions that patients have experienced themselves during their illness.

ETHICS AND DISSEMINATION

Under Danish regulations, ethical approval is not required for studies of this type. Written informed consent will be obtained from all patients. The study results will be published in peer-reviewed scientific journals and presented at national and international conferences. The modelling algorithms will be publicly available for statistical software, such as Stata and R.

No association between intravenous fluid volume and endothelial glycocalyx shedding in patients undergoing resuscitation for sepsis in the emergency department

Endothelial glycocalyx (EG) shedding is associated with septic shock and described following intravenous (IV) fluid administration. To investigate the possible impact of IV fluids on the pathobiology of septic shock we investigated associations between biomarkers of EG shedding and endothelial cell activation, and relationships with IV fluid volume. Serum samples were obtained on admission (T0) and at 24 h (T24) in patients undergoing haemodynamic resuscitation for suspected septic shock in the emergency department. Biomarkers of EG shedding—Syndecan-1 (Syn-1), Syndecan-4 (Syn-4), Hyaluronan, endothelial activation—Endothelin-1 (ET-1), Angiopoeitin-2 (Ang-2), Vascular Endothelial Growth Factor Receptor-1(VEGF-1) and leucocyte activation/inflammation—Resistin, Neutrophil Gelatinase Associated Lipocalin (NGAL) and a marker of cardiac stretch—Pro-Atrial Natriuretic Peptide (Pro-ANP) were compared to the total IV fluid volume administered using Tobit regression. Data on 86 patients (52 male) with a mean age of 60 (SD 18) years were included. The mean fluid volume administered to T24 was 4038 ml (SD 2507 ml). No significant association between fluid volume and Pro-ANP or any of the biomarkers were observed. Syn-1 and Syn-4 were significantly correlated with each other (Spearman Rho 0.43, p < 0.001) but not with Hyaluronan. Syn-1 and Syn-4 both correlated with VEGFR-1 (Rho 0.56 and 0.57 respectively, p < 0.001) whereas Hyaluronan correlated with ET-1 (Rho 0.43, p < 0.001) and Ang-2 (Rho 0.43, p < 0.001). There was no correlation between Pro-ANP and any of the EG biomarkers. Distinct patterns of association between biomarkers of EG shedding and endothelial cell activation were observed among patients undergoing resuscitation for sepsis. No relationship between IV fluid volume and Pro-ANP or any of the other biomarkers was observed.

Sepsis Management for the Nephrologist

The definition of sepsis has evolved significantly over the past three decades. Today, sepsis is defined as a dysregulated host immune response to microbial invasion leading to end organ dysfunction. Septic shock is characterized by hypotension requiring vasopressors after adequate fluid resuscitation with elevated lactate. Early recognition and intervention remain hallmarks for sepsis management. We addressed the current literature and assimilated thought regarding optimum initial resuscitation of the patient with sepsis. A nuanced understanding of the physiology of lactate is provided in our review. Physiologic and practical knowledge of steroid and vasopressor therapy for sepsis is crucial and addressed. As blood purification may interest the nephrologist treating sepsis, we have also added a brief discussion of its status.

Pathophysiology, mechanisms, and managements of tissue hypoxia

Oxygen is needed to generate aerobic adenosine triphosphate and energy that is required to support vital cellular functions. Oxygen delivery (DO₂) to the tissues is determined by convective and diffusive processes. The ability of the body to adjust oxygen extraction (ERO₂) in response to changes in DO₂ is crucial to maintain constant tissue oxygen consumption (VO₂). The capability to increase ERO₂ is the result of the regulation of the circulation and the effects of the simultaneous activation of both central and local factors. The endothelium plays a crucial role in matching tissue oxygen supply to demand in situations of acute drop in tissue oxygenation. Tissue oxygenation is adequate when tissue oxygen demand is met. When DO₂ is severely compromised, a critical DO₂ value is reached below which VO₂ falls and becomes dependent on DO₂, resulting in tissue hypoxia. The different mechanisms of tissue hypoxia are circulatory, anaemic, and hypoxic, characterised by a diminished DO₂ but preserved capacity of increasing ERO₂. Cytopathic hypoxia is another mechanism of tissue hypoxia that is due to impairment in mitochondrial respiration that can be observed in septic conditions with normal overall DO₂. Sepsis induces microcirculatory alterations with decreased functional capillary density, increased number of stopped-flow capillaries, and marked heterogeneity between the areas with large intercapillary distance, resulting in impairment of the tissue to extract oxygen and to satisfy the increased tissue oxygen demand, leading to the development of tissue hypoxia. Different therapeutic approaches exist to increase DO₂ and improve microcirculation, such as fluid therapy, transfusion, vasopressors, inotropes, and vasodilators. However, the effects of these agents on microcirculation are quite variable.

Restrictive Fluid Administration vs. Standard of Care in Emergency Department Sepsis Patients (REFACED Sepsis)-protocol for a multicenter, randomized, clinical, proof-of-concept trial

BACKGROUND

Intravenous fluids are often used in the treatment of sepsis. The better strategy regarding fluid volume is debated, but preliminary data in patients with septic shock or sepsis-related hypotension favor restrictive fluid administration. We describe the protocol and statistical analysis plan for the Restrictive Fluid Administration vs. Standard of Care in Emergency Department Sepsis Patients (REFACED Sepsis)-a multicenter, randomized clinical proof-of-concept trial. The aim of the REFACED Sepsis trial is to test if a restrictive intravenous fluid protocol in emergency department patients with sepsis without shock is feasible and decreases the intravenous fluid volume administered in comparison to standard care.

METHODS

This is an investigator-initiated, multicenter, randomized, parallel-group, open-labeled, feasibility trial investigating volumes of crystalloid fluid within 24 h in 124 patients with sepsis without shock enrolled at three emergency departments in the Central Denmark Region. Patients are allocated to two different intravenous fluid regimens: a restrictive approach using four trigger criteria for fluid administration vs. standard care. The primary, feasibility outcome is total intravenous, crystalloid fluid volume within 24 h, and key secondary outcomes include protocol violations, total fluids (intravenous and oral) within 24 h, and serious adverse reactions and suspected unexpected serious adverse reactions. Status: The trial started in November 2021, and the last patient is anticipated to be included in January 2022.

DISCUSSION

Sepsis is very common in emergency department patients and fluid administration is very frequently administered in these patients. However, the evidence to guide fluid administration is very sparse. This feasibility trial will be the foundation for a potential future large-scale trial investigating restrictive vs. standard fluid administration in patients with sepsis.

TRIAL REGISTRATION

EudraCT number: 2021-000224-35 (date: 2021 May 03), ClinicalTrials.gov number: NCT05076435 (date: 2021 October 13), Committee on Health Research Ethics - Central Denmark Region: 1-10-72-163-21 (date: 2021 June 28).

Fluid Overload Phenotypes in Critical Illness-A Machine Learning Approach

BACKGROUND

The detrimental impact of fluid overload (FO) on intensive care unit (ICU) morbidity and mortality is well known. However, research to identify subgroups of patients particularly prone to fluid overload is scarce. The aim of this cohort study was to derive "FO phenotypes" in the critically ill by using machine learning techniques.

METHODS

Retrospective single center study including adult intensive care patients with a length of stay of ≥3 days and sufficient data to compute FO. Data was analyzed by multivariable logistic regression, fast and frugal trees (FFT), classification decision trees (DT), and a random forest (RF) model.

RESULTS

Out of 1772 included patients, 387 (21.8%) met the FO definition. The random forest model had the highest area under the curve (AUC) (0.84, 95% CI 0.79-0.86), followed by multivariable logistic regression (0.81, 95% CI 0.77-0.86), FFT (0.75, 95% CI 0.69-0.79) and DT (0.73, 95% CI 0.68-0.78) to predict FO. The most important predictors identified in all models were lactate and bicarbonate at admission and postsurgical ICU admission. Sepsis/septic shock was identified as a risk factor in the MV and RF analysis.

CONCLUSION

The FO phenotypes consist of patients admitted after surgery or with sepsis/septic shock with high lactate and low bicarbonate.

Interactions in clinical trials: Protocol and statistical analysis plan for an explorative study of four randomized ICU trials on use of pantoprazole, oxygenation targets, haloperidol and intravenous fluids

BACKGROUND

Intensive care unit (ICU) patients receive numerous interventions, but knowledge about potential interactions between these interventions is limited. Co-enrolment in randomized clinical trials represents a unique opportunity to investigate any such interactions. We aim to assess interactions in four randomized clinical trials with overlap in inclusion periods and patient populations.

METHODS

This protocol and statistical analysis plan describes a secondary explorative analysis of interactions in four international ICU trials on pantoprazole, oxygenations targets, haloperidol and intravenous fluids, respectively. The primary outcome will be 90-day all-cause mortality. The secondary outcome will be days alive and out of hospital in 90 days after randomization. All patients included in the intention-to-treat populations of the four trials will be included. Four co-primary analyses will be conducted, one with each of the included trials as reference using a logistic regression model adjusted for the reference trial's stratification variables and for the co-interventions with interactions terms. The primary analytical measure of interest will be the analyses' tests of interaction. A p-value below .05 will be considered statically significant. The stratification variable- and co-intervention-adjusted effect estimates will be reported with 95% confidence intervals without adjustments for multiplicity.

CONCLUSION

This exploratory analysis will investigate the presence of any interactions between pantoprazole, oxygenation targets, haloperidol and amount of intravenous fluids in four international ICU trials using co-enrolment. Assessment of possible interactions represents valuable information to guide the design, statistical powering and conduct of future trials.

Twenty-four-hour fluid administration in emergency department patients with suspected infection: A multicenter, prospective, observational study

BACKGROUND

To describe 24-hour fluid administration in emergency department (ED) patients with suspected infection.

METHODS

A prospective, multicenter, observational study conducted in three Danish hospitals, January 20 to March 2, 2020. We included consecutive adult ED patients with suspected infection (drawing of blood culture and/or intravenous antibiotic administration within 6 hours of admission). Oral and intravenous fluids were registered for 24 hours.

PRIMARY OUTCOME

24-hour total fluid volume. We used linear regression to investigate patient and disease characteristics' effect on 24-hour fluids and to estimate the proportion of the variance in fluid administration explained by potential predictors.

RESULTS

734 patients had 24-hour fluids available: 387 patients had simple infection, 339 sepsis, eight septic shock. Mean total 24-hour fluid volumes were 3656 mL (standard deviation [SD]:1675), 3762 mL (SD: 1839), and 6080 mL (SD: 3978) for the groups, respectively. Fluid volumes varied markedly. Increasing age (mean difference [MD]: 60-79 years: -470 mL [95% CI: -789, -150], +80 years; -974 mL [95% CI: -1307, -640]), do-not-resuscitate orders (MD: -466 mL [95% CI: -797, -135]), and preexisting atrial fibrillation (MD: -367 mL [95% CI: -661, -72) were associated with less fluid. Systolic blood pressure < 100 mmHg (MD: 1182 mL [95% CI: 820, 1543]), mean arterial pressure < 65 mmHg (MD: 1317 mL [95% CI: 770, 1864]), lactate ≥ 2 mmol/L (MD: 655 mL [95% CI: 306, 1005]), heart rate > 120 min (MD: 566 [95% CI: 169, 962]), low (MD: 1963 mL [95% CI: 813, 3112]) and high temperature (MD: 489 mL [95% CI: 234, 742]), SOFA score > 5 (MD: 1005 mL [95% CI: 501, 510]), and new-onset atrial fibrillation (MD: 498 mL [95% CI: 30, 965]) were associated with more fluid. Clinical variables explained 37% of fluid variation among patients.

CONCLUSIONS

Patients with simple infection and sepsis received equal fluid volumes. Fluid volumes varied markedly, a variation that was partly explained by clinical characteristics.

Patient-important outcomes other than mortality in recent ICU trials: Protocol for a scoping review

BACKGROUND

Randomised clinical trials (RCTs) conducted in intensive care units (ICUs) frequently focus on all-cause mortality, but other patient-important outcomes are increasingly used and recommended. Their use, however, is not straightforward: choices and definitions, operationalisation of death, handling of missing data, choice of effect measures, and statistical analyses for these outcomes vary greatly.

METHODS

We will conduct a scoping review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews. We will search 10 selected general and speciality journals for RCTs conducted in adult ICU patients from 2018 and onwards reporting at least 1 patient-important outcome other than mortality (including days alive without life support/days alive and out of hospital-type outcomes, health-related quality of life, functional/cognitive/neurological outcomes, and other general patient-important outcomes). We will summarise data on outcome measures and definitions, assessment time points, proportions and handling of death, proportions and handling of missing data, and effect measures and statistical methods used for analysis.

DISCUSSION

The outlined scoping review will provide an overview of choices, definitions and handling of patient-important outcomes other than mortality in contemporary RCTs conducted in adult ICU patients. This may guide discussions with patients and relatives, the design of future RCTs, and research on optimal outcome choices and handling.

Restrictive fluid management versus usual care in acute kidney injury (REVERSE-AKI): a pilot randomized controlled feasibility trial

Purpose

We compared a restrictive fluid management strategy to usual care among critically ill patients with acute kidney injury (AKI) who had received initial fluid resuscitation.

Methods

This multicenter feasibility trial randomized 100 AKI patients 1:1 in seven ICUs in Europe and Australia. Restrictive fluid management included targeting negative or neutral daily fluid balance by minimizing fluid input and/or enhancing urine output with diuretics administered at the discretion of the clinician. Fluid boluses were administered as clinically indicated. The primary endpoint was cumulative fluid balance 72 h from randomization.

Results

Mean (SD) cumulative fluid balance at 72 h from randomization was − 1080 mL (2003 mL) in the restrictive fluid management arm and 61 mL (3131 mL) in the usual care arm, mean difference (95% CI) − 1148 mL (− 2200 to − 96) mL, P = 0.033. Median [IQR] duration of AKI was 2 [1–3] and 3 [2–7] days, respectively (median difference − 1.0 [− 3.0 to 0.0], P = 0.071). Altogether, 6 out of 46 (13%) patients in the restrictive fluid management arm and 15 out of 50 (30%) in the usual care arm received renal replacement therapy (RR 0.42; 95% CI 0.16–0.91), P = 0.043. Cumulative fluid balance at 24 h and 7 days was lower in the restrictive fluid management arm. The dose of diuretics was not different between the groups. Adverse events occurred more frequently in the usual care arm.

Conclusions

In critically ill patients with AKI, a restrictive fluid management regimen resulted in lower cumulative fluid balance and less adverse events compared to usual care. Larger trials of this intervention are justified.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06401-6.

Challenges in the recognition and management of paediatric sepsis - The journey

Paediatric sepsis remains a leading cause of childhood death. Morbidity is high, with up to one third of children affected developing ongoing, sometimes lifelong sequelae. To address the major burden of sepsis on child health, there is need for a unified approach to care, as outlined in the Australian National Action Plan for sepsis. While the Surviving Sepsis Campaign 2020 guidelines provided evidence-based recommendations for sepsis management in hospital, additional emphasis on families, pre-hospital recognition and post-sepsis care incorporating the multidisciplinary team is paramount to achieve quality patient outcomes. The role of families, paramedics and nurses in recognising and managing paediatric sepsis remains an under-represented area in current literature. The aim of this paper is to critically discuss key challenges surrounding the journey of paediatric sepsis, drawing on contemporary literature to highlight key areas pertinent to recognition and management of sepsis in children. Application of a holistic, patient-centred focus will provide an overview of paediatric sepsis, aiming to inform future development for enhanced healthcare delivery and identify critical areas for further research.

Noninterventional follow-up vs fluid bolus in RESPONSE to oliguria-The RESPONSE trial protocol and statistical analysis plan

BACKGROUND

Oliguria is a frequent trigger for administering a fluid bolus, but the effect of fluid bolus in improving urine output is inadequately demonstrated. Here, we summarize the protocol and detailed statistical analysis plan of the randomized, controlled RESPONSE trial comparing follow-up as the experimental group and a 500 mL crystalloid fluid bolus as the control group for oliguria in critically ill oliguric patients.

METHODS

Our trial is an investigator-initiated, randomized, controlled, pilot trial conducted in three ICUs in two centers. We aim to randomize 1:1 altogether 130 hemodynamically stable oliguric patients either to a 2-hour follow-up without interventions or to receive a crystalloid bolus of 500 mL over 30 minutes. The primary outcome is the change in individual urine output during the 2-hour period compared to 2 hours preceding randomization. Doubling of the urine output is considered clinically significant. Additionally, we record the duration of oliguria, physiological and biochemical variables, adverse events, and the incidences of acute kidney injury and renal replacement therapy.

CONCLUSIONS

Oliguria is a frequent trigger for potentially harmful fluid loading. Therefore, the RESPONSE trial will give information of the potential effect of fluid bolus on oliguria in critically ill patients.

TRIAL REGISTRATION

clinical.trials.gov, NCT02860572.

Long-term patient-important outcomes after septic shock: A protocol for 1-year follow-up of the CLASSIC trial

BACKGROUND

In patients with septic shock, mortality is high, and survivors experience long-term physical, mental and social impairments. The ongoing Conservative vs Liberal Approach to fluid therapy of Septic Shock in Intensive Care (CLASSIC) trial assesses the benefits and harms of a restrictive vs standard-care intravenous (IV) fluid therapy. The hypothesis is that IV fluid restriction improves patient-important long-term outcomes.

AIM

To assess the predefined patient-important long-term outcomes in patients randomised into the CLASSIC trial.

METHODS

In this pre-planned follow-up study of the CLASSIC trial, we will assess all-cause mortality, health-related quality of life (HRQoL) and cognitive function 1 year after randomisation in the two intervention groups. The 1-year mortality will be collected from electronic patient records or central national registries in most participating countries. We will contact survivors and assess EuroQol 5-Dimension, -5-Level (EQ-5D-5L) and EuroQol-Visual Analogue Scale and Montreal Cognitive Assessment 5-minute protocol score. We will analyse mortality by logistic regression and use general linear models to assess HRQoL and cognitive function.

DISCUSSION

With this pre-planned follow-up study of the CLASSIC trial, we will provide patient-important data on long-term survival, HRQoL and cognitive function of restrictive vs standard-care IV fluid therapy in patients with septic shock.

Survey of non-resuscitation fluids administered during septic shock: a multicenter prospective observational study

BACKGROUND

The indication, composition and timing of administration of non-resuscitation fluid in septic shock have so far received little attention and accordingly the potential to reduce this source of fluid is unknown. The objective of the study was to quantify and characterize non-resuscitation fluid administered to patients with septic shock.

METHODS

This prospective observational study was performed in eight intensive care units in Sweden and Canada during 4 months in 2018. Adult patients with septic shock within 24 h of admission to the intensive care unit were eligible for inclusion. Non-resuscitation fluids were defined as fluids other than colloids, blood products and crystalloids at a rate ≥ 5 ml/kg/h. Indication, volume and type of fluid were recorded during the first 5 days after admission. A maximum of 30 patients could be included per centre. To estimate the potential to reduce administration of non-resuscitation fluid, a pragmatic "restrictive" protocol for administration of non-resuscitation fluids was devised based on the most restrictive practice already in place for non-resuscitation fluids at any of the participating centres. Data are presented as median (interquartile range [IQR]).

RESULTS

A total of 200 patients were included in the study and the 30-day mortality was 35%. Patients received a total of 7870 (4060-12,340) ml of non-resuscitation fluids and 2820 (1430-4580) of resuscitation fluids during the observation period. Median volumes of non-resuscitation and resuscitation fluids were similar at day 1 (1620 [710-2320] and 1590 [520-3000]) ml, respectively) and non-resuscitation fluids represented the largest source of fluid from day 2 and onwards after admission to the ICU. Vehicles for drugs such as vasoactive drugs and antibiotics constituted the largest fraction of non-resuscitation fluids (2400 [1270-4030] ml) during the 5-day observation period. Modelling suggested that volume of non-resuscitation fluids could be reduced by 2840 (1270-4900) ml during the first 5 days of admission to the ICU, mainly through reducing maintenance fluids.

CONCLUSIONS

Non-resuscitation fluids constitute the major fraction of fluids administered in the ICU to patients suffering from septic shock and may represent the largest modifiable target to reduce fluid overload.