Balanced crystalloids versus saline in the intensive care unit: study protocol for a cluster-randomized, multiple-crossover trial

Potassium level changes in chronic kidney disease patients following balanced crystalloid administration in the emergency department

One common reason why clinicians are often hesitate to administer balanced crystalloids in the emergency department is the potential occurrence of unexpected hyperkalemia in patients with chronic kidney disease (CKD). In order to investigate the changes in potassium levels resulting from the administration of balanced crystalloids, specially Plasma Solution A (a generic version of Plasma-Lyte), to emergency department patients with CKD, we conducted an evaluation. A retrospective cohort study was conducted at a single academic hospital. Our study included patients with CKD who received intravenous Plasma Solution A and underwent electrolyte follow-up testing within 24 hours of administration. In total, there were 745 patients included in this study, of whom 87 had CKD. Through a 1:1 propensity score matching procedure for factors other than the estimated glomerular filtration rate, we matched 87 patients with normal kidney function to 87 CKD patients. For patients with CKD, the mean standard deviation SD administered volume of Plasma Solution A was 28.7 (21.0) mL/kg, and the mean SD administration duration was 13.2 (4.5) hours. The mean SD potassium level decreased from 4.3 (0.6) mmol/L to 4.1 (0.6) mmol/L (P = .029). Our study findings suggest that there may be no significant harmful increase in potassium levels or worsening of renal function within 24 hours after the intravenous administration of approximately 2 L of Plasma Solution A to patients with CKD.

Postoperative Fluid Therapy in Adult Cardiac Surgical Patients and Acute Kidney Injury: A Prospective Observational Study

Background Normal saline (0.9% NS) is a common intravenous fluid used worldwide. Recent studies have shown that NS use is associated with increased incidence of acute kidney injury (AKI) and a need for renal replacement therapy (RRT). The practice is changing toward using balanced solutions to prevent AKI. Postcardiac surgery patients are more prone to develop AKI after cardiopulmonary bypass (CPB). We aim to study the type of fluid administrated, incidence of AKI, need for RRT, and overall outcome of these patients.

Methods This prospective observational study was conducted in the cardiothoracic intensive care unit (cardiothoracic and vascular surgery intensive care unit) in a cohort of 197 adult patients who underwent on pump cardiac surgery in our hospital from July 2021 to October 2021 as a pilot study. Data was analyzed using SPSS 20.0 (IBM, Chicago, Illinois, United States). A p-value < 0.05 was considered significant.

Results In our study, 58 (29.34%) patients developed AKI in the first three postoperative days and 16 (8.12%) patients required RRT. Incidence of AKI was found to be higher in patients who received NS only, as fluid of choice was 34.48% compared with other intravenous fluids. Patients with AKI had higher positive fluid balance (p < 0.001), longer CPB (p < 0.001), and aortic cross clamp (p = 0.006) times. Intensive care unit and hospital stay and mortality rates were higher in AKI patients than those without AKI (p < 0.001).

Conclusion Our study demonstrated that NS was the commonly used crystalloid in our patients and was associated with increased incidence of AKI and RRT when compared with other balanced salts solutions.

Protocol and statistical analysis plan for the Pragmatic Investigation of optimaL Oxygen Targets (PILOT) clinical trial

INTRODUCTION

Mechanical ventilation of intensive care unit (ICU) patients universally involves titration of the fraction of inspired oxygen to maintain arterial oxygen saturation (SpO2). However, the optimal SpO2 target remains unknown.

METHODS AND ANALYSIS

The Pragmatic Investigation of optimaL Oxygen Targets (PILOT) trial is a prospective, unblinded, pragmatic, cluster-crossover trial being conducted in the emergency department (ED) and medical ICU at Vanderbilt University Medical Center in Nashville, Tennessee, USA. PILOT compares use of a lower SpO2 target (target 90% and goal range: 88%-92%), an intermediate SpO2 target (target 94% and goal range: 92%-96%) and a higher SpO2 target (target 98% and goal range: 96%-100%). The study units are assigned to a single SpO2 target (cluster-level allocation) for each 2-month study block, and the assigned SpO2 target switches every 2 months in a randomly generated sequence (cluster-level crossover). The primary outcome is ventilator-free days (VFDs) to study day 28, defined as the number of days alive and free of invasive mechanical ventilation from the final receipt of invasive mechanical ventilation through 28 days after enrolment.

ETHICS AND DISSEMINATION

The trial was approved by the Vanderbilt Institutional Review Board. The results will be submitted for publication in a peer-reviewed journal and presented at one or more scientific conferences.

TRIAL REGISTRATION NUMBER

The trial protocol was registered with ClinicalTrials.gov on 25 May 2018 prior to initiation of patient enrolment (ClinicalTrials.gov identifier: NCT03537937).

Effect of balanced crystalloids versus saline on urinary biomarkers of acute kidney injury in critically ill adults

Background

Recent trials have suggested use of balanced crystalloids may decrease the incidence of major adverse kidney events compared to saline in critically ill adults. The effect of crystalloid composition on biomarkers of early acute kidney injury remains unknown.

Methods

From February 15 to July 15, 2016, we conducted an ancillary study to the Isotonic Solutions and Major Adverse Renal Events Trial (SMART) comparing the effect of balanced crystalloids versus saline on urinary levels of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) among 261 consecutively-enrolled critically ill adults admitted from the emergency department to the medical ICU. After informed consent, we collected urine 36 ± 12 h after hospital admission and measured NGAL and KIM-1 levels using commercially available ELISAs. Levels of NGAL and KIM-1 at 36 ± 12 h were compared between patients assigned to balanced crystalloids versus saline using a Mann-Whitney U test.

Results

The 131 patients (50.2%) assigned to the balanced crystalloid group and the 130 patients (49.8%) assigned to the saline group were similar at baseline. Urinary NGAL levels were significantly lower in the balanced crystalloid group (median, 39.4 ng/mg [IQR 9.9 to 133.2]) compared with the saline group (median, 64.4 ng/mg [IQR 27.6 to 339.9]) (P < 0.001). Urinary KIM-1 levels did not significantly differ between the balanced crystalloid group (median, 2.7 ng/mg [IQR 1.5 to 4.9]) and the saline group (median, 2.4 ng/mg [IQR 1.3 to 5.0]) (P = 0.36).

Conclusions

In this ancillary analysis of a clinical trial comparing balanced crystalloids to saline among critically ill adults, balanced crystalloids were associated with lower urinary concentrations of NGAL and similar urinary concentrations of KIM-1, compared with saline. These results suggest only a modest reduction in early biomarkers of acute kidney injury with use of balanced crystalloids compared with saline.

Trial registration

ClinicalTrials.gov number: NCT02444988. Date registered: May 15, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02236-x.

Clinical Effects of Balanced Crystalloids vs Saline in Adults With Diabetic Ketoacidosis: A Subgroup Analysis of Cluster Randomized Clinical Trials

IMPORTANCE

Saline (0.9% sodium chloride), the fluid most commonly used to treat diabetic ketoacidosis (DKA), can cause hyperchloremic metabolic acidosis. Balanced crystalloids, an alternative class of fluids for volume expansion, do not cause acidosis and, therefore, may lead to faster resolution of DKA than saline.

OBJECTIVE

To compare the clinical effects of balanced crystalloids with the clinical effects of saline for the acute treatment of adults with DKA.

DESIGN, SETTING, AND PARTICIPANTS

This study was a subgroup analysis of adults with DKA in 2 previously reported companion trials-Saline Against Lactated Ringer's or Plasma-Lyte in the Emergency Department (SALT-ED) and the Isotonic Solutions and Major Adverse Renal Events Trial (SMART). These trials, conducted between January 2016 and March 2017 in an academic medical center in the US, were pragmatic, multiple-crossover, cluster, randomized clinical trials comparing balanced crystalloids vs saline in emergency department (ED) and intensive care unit (ICU) patients. This study included adults who presented to the ED with DKA, defined as a clinical diagnosis of DKA, plasma glucose greater than 250 mg/dL, plasma bicarbonate less than or equal to 18 mmol/L, and anion gap greater than 10 mmol/L. Data analysis was performed from January to April 2020.

INTERVENTIONS

Balanced crystalloids (clinician's choice of Ringer lactate solution or Plasma-Lyte A solution) vs saline for fluid administration in the ED and ICU according to the same cluster-randomized multiple-crossover schedule.

MAIN OUTCOMES AND MEASURES

The primary outcome was time between ED presentation and DKA resolution, as defined by American Diabetes Association criteria. The secondary outcome was time between initiation and discontinuation of continuous insulin infusion.

RESULTS

Among 172 adults included in this secondary analysis of cluster trials, 94 were assigned to balanced crystalloids and 78 to saline. The median (interquartile range [IQR]) age was 29 (24-45) years, and 90 (52.3%) were women. The median (IQR) volume of isotonic fluid administered in the ED and ICU was 4478 (3000-6372) mL. Cumulative incidence analysis revealed shorter time to DKA resolution in the balanced crystalloids group (median time to resolution: 13.0 hours; IQR: 9.5-18.8 hours) than the saline group (median: 16.9 hours; IQR: 11.9-34.5 hours) (adjusted hazard ratio [aHR] = 1.68; 95% CI, 1.18-2.38; P = .004). Cumulative incidence analysis also revealed shorter time to insulin infusion discontinuation in the balanced crystalloids group (median: 9.8 hours; IQR: 5.1-17.0 hours) than the saline group (median: 13.4 hours; IQR: 11.0-17.9 hours) (aHR = 1.45; 95% CI, 1.03-2.03; P = .03).

CONCLUSIONS AND RELEVANCE

In this secondary analysis of 2 cluster randomized clinical trials, compared with saline, treatment with balanced crystalloids resulted in more rapid resolution of DKA, suggesting that balanced crystalloids may be preferred over saline for acute management of adults with DKA.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT02614040; NCT02444988.

Managing Chloride and Bicarbonate in the Prevention and Treatment of Acute Kidney Injury

Intravenous crystalloid therapy is one of the most ubiquitous aspects of hospital and critical care medicine. In recent years, there has been increasing focus on the electrolyte composition, and particularly chloride content, of crystalloid solutions. This has led to increasing clinical adoption of balanced solutions, containing substrates for bicarbonate generation and consequently a lower chloride content, in place of 0.9% saline. In this article we review the physiochemical rationale for avoidance of 0.9% saline and the effects of hyperchloremic acidosis on renal physiology. Finally, we review the current evidence and rationale for use of balanced solutions greater than 0.9% saline in acutely ill patients in a variety of clinical settings, as well as considering the role for sodium bicarbonate in preventing or correcting metabolic acidosis. In conclusion, there is a strong physiological rationale for avoidance of iatrogenic hyperchloremic acidosis from 0.9% saline administration in acutely unwell patients and an association with adverse renal outcomes in several studies. However, evidence from large definitive multicenter randomized trials is not yet available to establish the dose-relationship between 0.9% saline administration and potential harm and inform us if some 0.9% saline use is acceptable or if any exposure confers harm.

Balanced Crystalloids versus Saline in Sepsis. A Secondary Analysis of the SMART Clinical Trial

Rationale: Administration of intravenous crystalloid solutions is a fundamental therapy for sepsis, but the effect of crystalloid composition on patient outcomes remains unknown.Objectives: To compare the effect of balanced crystalloids versus saline on 30-day in-hospital mortality among critically ill adults with sepsis.Methods: Secondary analysis of patients from SMART (Isotonic Solutions and Major Adverse Renal Events Trial) admitted to the medical ICU with an International Classification of Diseases, 10th Edition, Clinical Modification System code for sepsis, using multivariable regression to control for potential confounders.Measurements and Main Results: Of 15,802 patients enrolled in SMART, 1,641 patients were admitted to the medical ICU with a diagnosis of sepsis. A total of 217 patients (26.3%) in the balanced crystalloids group experienced 30-day in-hospital morality compared with 255 patients (31.2%) in the saline group (adjusted odds ratio [aOR], 0.74; 95% confidence interval [CI], 0.59-0.93; P = 0.01). Patients in the balanced group experienced a lower incidence of major adverse kidney events within 30 days (35.4% vs. 40.1%; aOR, 0.78; 95% CI, 0.63-0.97) and a greater number of vasopressor-free days (20 ± 12 vs. 19 ± 13; aOR, 1.25; 95% CI, 1.02-1.54) and renal replacement therapy-free days (20 ± 12 vs. 19 ± 13; aOR, 1.35; 95% CI, 1.08-1.69) compared with the saline group.Conclusions: Among patients with sepsis in a large randomized trial, use of balanced crystalloids was associated with a lower 30-day in-hospital mortality compared with use of saline.Clinical trial registered with www.clinicaltrials.gov (NCT02444988).

Choice of Intravenous Crystalloid Fluid and Mortality in Critically Ill Adult Patients

OBJECTIVES

Intravenous balanced crystalloid fluid therapy may improve mortality and other outcomes in critically ill adult patients, but data are conflicting. We conducted a meta-analysis and literature review to evaluate the impact of intravenous balanced crystalloid, as compared with normal saline, fluid therapy on outcomes in critically ill adult patients.

METHODS

We searched PubMed, Scopus, MEDLINE, and the Cochrane Register of Clinical Trials for relevant studies. Randomized controlled trials comparing the effects of balanced intravenous crystalloids with normal saline on intensive care unit (ICU) or hospital mortality were included. Pooled risk ratios (RRs) were calculated using a fixed effects model. Heterogeneity was calculated using the I² statistic. The risk of bias was assessed using the Cochrane tool.

RESULTS

Seven randomized controlled trials with 20,171 patients (10,179 participants received balanced crystalloids and 9992 participants received normal saline) were included. For hospital mortality, the pooled RR (95% confidence interval [CI]) was 0.92 (0.85-1.00). For ICU mortality, the pooled RR (95% CI) was 0.91 (0.82-1.00). For major adverse kidney events at 30 days, pooled RR (95% CI) was 0.95 (0.88-1.01). For stage ≥2 acute kidney injury, the pooled RR (95% CI) was 0.94 (0.86-1.02). For receipt of new renal replacement therapy, the pooled RR (95% CI) was 0.91 (0.77-1.07). None of these findings reached statistical significance.

CONCLUSIONS

Intravenous balanced crystalloid use, compared with normal saline, does not result in a statistically significant reduction in hospital or ICU mortality, major adverse kidney events at 30 days, stage ≥2 acute kidney injury, or receipt of new renal replacement therapy in critically ill adult patients.

Impact of Point-of-Care Ultrasound in the Emergency Department on Care Processes and Outcomes in Critically Ill Nontraumatic Patients

Supplemental Digital Content is available in the text.

Outcomes data on point-of-care ultrasound (POCUS) in critically ill patients are lacking. This study examines the association between POCUS in the emergency department and outcomes in critically ill patients.

Validation of a Sequential Organ Failure Assessment Score using Electronic Health Record Data

The sequential organ failure assessment (SOFA) score is a scoring system commonly used in critical care to assess severity of illness. Automated calculation of the SOFA score using existing electronic health record data would broaden its applicability. We performed a manual validation of an automated SOFA score previously developed at our institution. A retrospective analysis of a random subset of 300 patients from a previously published randomized trial of critically ill adults was performed, with manual validation of SOFA scores from the date of initial intensive care unit admission. Spearman's rank correlation coefficient, weighted Cohen's kappa, and Bland-Altman plots were used to assess agreement between manual and electronic versions of SOFA scores and between manual and electronic versions of their individual components. There was high agreement between manual and electronic SOFA scores (Spearman's rank correlation coefficient = 0.90, 95% CI 0.87-0.93). Renal and respiratory components had lower agreement (weighted Cohen's kappa = 0.63, 95% CI 0.53-0.73 for renal; weighted Cohen's kappa = 0.77, 95% CI 0.70-0.84 for respiratory). The area under the receiver operating characteristic curve (AUC) for 30-day in-hospital mortality was 0.77 (95% CI 0.68-0.84) for manual SOFA scores and 0.75 (95% CI 0.66-0.83) for automated SOFA scores. Automatic calculation of SOFA scores from the electronic health record is feasible and correlates highly with manually calculated SOFA scores. Both have similar predictive value for 30-day in-hospital mortality.

Balanced Crystalloids versus Saline in Critically Ill Adults

BACKGROUND:

Both balanced crystalloids and saline are used for intravenous fluid administration among critically ill adults. Which results in better clinical outcomes remains unknown.

METHODS:

In a pragmatic, cluster-randomized, multiple-crossover trial in five intensive care units at an academic center, we assigned 15,802 adults to receive saline (0.9% sodium chloride) or balanced crystalloids (lactated Ringer’s solution or Plasma-Lyte A®), according to the randomization of the unit to which they were admitted. The primary outcome was Major Adverse Kidney Events within 30 days (MAKE30), i.e., the composite of death, new renal replacement therapy, or persistent creatinine elevation ≥ 200% of baseline – all censored at the first of hospital discharge or 30 days.

RESULTS:

In the balanced crystalloid group, 1,139 patients (14.3%) experienced MAKE30, compared to 1,211 patients (15.4%) in the saline group (marginal odds ratio, 0.91; 95% confidence interval, 0.84–0.99; conditional odds ratio, 0.90; 95% confidence interval, 0.82–0.99; P=0.04). Thirty-day in-hospital mortality was 10.3% in the balanced crystalloid group and 11.1% in the saline group (P=0.06). The incidence of new renal replacement therapy was 2.5% and 2.9% respectively (P=0.08), and the incidence of persistent creatinine elevation was 6.4% and 6.6% respectively (P=0.60).

CONCLUSIONS:

Among critically ill adults, the use of balanced crystalloids for intravenous fluid administration appeared to reduce the composite outcome of in-hospital mortality, new renal replacement therapy, and persistent renal dysfunction compared with the use of saline. (SMART-MED and SMART-SURG ClinicalTrials.gov numbers, NCT02444988 and NCT02547779.)

Crystalloid fluid choice in the critically ill : Current knowledge and critical appraisal

Intravenous infusion of crystalloid solutions is one of the most frequently administered medications worldwide. Available crystalloid infusion solutions have a variety of compositions and have a major impact on body systems; however, administration of crystalloid fluids currently follows a "one fluid for all" approach than a patient-centered fluid prescription. Normal saline is associated with hyperchloremic metabolic acidosis, increased rates of acute kidney injury, increased hemodynamic instability and potentially mortality. Regarding balanced infusates, evidence remains less clear since most studies compared normal saline to buffered infusion solutes.; however, buffered solutes are not homogeneous. The term "buffered solutes" only refers to the concept of acid-buffering in infusion fluids but this does not necessarily imply that the solutes have similar physiological impacts. The currently available data indicate that balanced infusates might have some advantages; however, evidence still is inconclusive. Taking the available evidence together, there is no single fluid that is superior for all patients and settings, because all currently available infusates have distinct differences, advantages and disadvantages; therefore, it seems inevitable to abandon the "one fluid for all" strategy towards a more differentiated and patient-centered approach to fluid therapy in the critically ill.

Balanced Crystalloids versus Saline in Critically Ill Adults

BACKGROUND

Both balanced crystalloids and saline are used for intravenous fluid administration in critically ill adults, but it is not known which results in better clinical outcomes.

METHODS

In a pragmatic, cluster-randomized, multiple-crossover trial conducted in five intensive care units at an academic center, we assigned 15,802 adults to receive saline (0.9% sodium chloride) or balanced crystalloids (lactated Ringer's solution or Plasma-Lyte A) according to the randomization of the unit to which they were admitted. The primary outcome was a major adverse kidney event within 30 days - a composite of death from any cause, new renal-replacement therapy, or persistent renal dysfunction (defined as an elevation of the creatinine level to ≥200% of baseline) - all censored at hospital discharge or 30 days, whichever occurred first.

RESULTS

Among the 7942 patients in the balanced-crystalloids group, 1139 (14.3%) had a major adverse kidney event, as compared with 1211 of 7860 patients (15.4%) in the saline group (marginal odds ratio, 0.91; 95% confidence interval [CI], 0.84 to 0.99; conditional odds ratio, 0.90; 95% CI, 0.82 to 0.99; P=0.04). In-hospital mortality at 30 days was 10.3% in the balanced-crystalloids group and 11.1% in the saline group (P=0.06). The incidence of new renal-replacement therapy was 2.5% and 2.9%, respectively (P=0.08), and the incidence of persistent renal dysfunction was 6.4% and 6.6%, respectively (P=0.60).

CONCLUSIONS

Among critically ill adults, the use of balanced crystalloids for intravenous fluid administration resulted in a lower rate of the composite outcome of death from any cause, new renal-replacement therapy, or persistent renal dysfunction than the use of saline. (Funded by the Vanderbilt Institute for Clinical and Translational Research and others; SMART-MED and SMART-SURG ClinicalTrials.gov numbers, NCT02444988 and NCT02547779 .).

Does Fluid Type and Amount Affect Kidney Function in Critical Illness?

Acute kidney injury (AKI) is common, although commonly used clinical diagnostic markers are imperfect. Intravenous fluid administration remains a cornerstone of therapy worldwide, but there is minimal evidence of efficacy for the use of fluid bolus therapy outside of specific circumstances, and emerging evidence associates fluid accumulation with worse renal outcomes and even increased mortality among critically ill patients. Artificial colloid solutions have been associated with harm, and chloride-rich solutions may adversely affect renal function. Large trials to provide guidance regarding the optimal fluid choices to prevent or ameliorate AKI, and promote renal recovery, are urgently required.

Balanced crystalloids vs 0.9% saline for adult patients undergoing non-renal surgery: A meta-analysis

BACKGROUND

Fluid maintenance and resuscitation is an important strategy during major surgeries. There has been a debate on the choice of crystalloids over the past decades. 0.9% saline (normal saline) is more likely to cause hyperchloremic acidosis when compared to balanced crystalloids with low chloride content. Meta-analyses comparing these two kinds of crystalloids have been performed in renal transplantations. We aim to compare the safety of balanced crystalloids to normal saline among adult patients undergoing non-renal surgery.

METHODS

Relevant articles were searched through PubMed, Embase and the Cochrane Library. Nine randomized controlled trials (including 871 participants) comparing balanced crystalloids to normal saline on adult patients undergoing non-renal surgery were finally included. Possible effects were calculated using meta-analysis.

RESULTS

Patients in the normal saline group had significantly lower postoperative pH (MD: 0.05; 95% CI: 0.04-0.06; p < .001; I² = 82%) and base excess (MD: 2.04; 95% CI: 1.44-2.65; p < .001; I² = 87%). The postoperative serum chloride level was significantly higher in the normal saline group (MD: -4.79; 95% CI: -8.13∼-1.45; p = .005; I² = 95%).

CONCLUSION

Comparing to normal saline, balanced crystalloids are more beneficial in keeping postoperative electrolytes and acid-base balance among adult patients undergoing non-renal surgery. Future researches should pay more attention to meaningful clinical outcomes concerning the safety of balanced crystalloids and normal saline.

Impact of volume status and volume therapy on the kidney

Volume resuscitation to correct hypotension in surgical and critically ill patients is a common practice. Available evidence suggests that iatrogenic volume overload is associated with worse outcomes in established acute kidney injury. Intraoperative arterial hypotension is associated with postoperative renal dysfunction, and prompt correction with fluid management protocols that combine inotrope infusions with volume therapy targeted to indices of volume responsiveness should be considered. From the perspective of renal function, the minimum amount of intravenous fluid required to maintain perfusion and oxygen delivery is desirable. Available evidence and expert opinion suggest that balanced crystalloid solutions are preferable to isotonic saline for volume resuscitation. Moreover, albumin has a similar safety profile as crystalloids. Hetastarch-containing colloids have a clear association with acute kidney injury.