Perioperative buffered versus non-buffered fluid administration for surgery in adults

A Hospital-Wide Open-Label Cluster Crossover Pragmatic Comparative Effectiveness Randomized Trial Comparing Normal Saline to Ringer's Lactate: Protocol and Statistical Analysis Plan of The FLUID Trial

BACKGROUND

Normal saline (NS) and Ringer's lactate (RL) are the most common crystalloids given to hospitalized patients. Despite concern about possible harm associated with NS (eg, hyperchloremic metabolic acidosis, impaired kidney function, and death), few large multicenter randomized trials focused on critically ill patients have compared these fluids. Uncertainty exists about the effects of these fluids on clinically important outcomes across all hospitalized patients.

OBJECTIVE

The FLUID trial is a pragmatic, multicenter, 2×2 cluster crossover comparative effectiveness randomized trial that aims to evaluate the effectiveness of a hospital-wide policy that stocks either NS or RL as the main crystalloid fluid in 16 hospitals across Ontario, Canada.

METHODS

All hospitalized adult and pediatric patients (anticipated sample size 144,000 patients) with an incident admission to the hospital over the course of each study period will be included. Either NS or RL will be preferentially stocked throughout the hospital for 12 weeks before crossing to the alternate fluid for the subsequent 12 weeks. The primary outcome is a composite of death and hospital readmission within 90 days of hospitalization. Secondary outcomes include death, hospital readmission, dialysis, reoperation, postoperative reintubation, length of hospital stay, emergency department visits, and discharge to a facility other than home. All outcomes will be obtained from health administrative data, eliminating the need for individual case reports. The primary analysis will use cluster-level summaries to estimate cluster-average treatment effects.

RESULTS

The statistical analysis plan has been prepared "a priori" in advance of receipt of the trial data set from ICES and any analyses.

CONCLUSIONS

We describe the protocol and statistical analysis plan for the evaluation of primary and secondary outcomes for the FLUID trial.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04512950; https://classic.clinicaltrials.gov/ct2/show/NCT04512950.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/51783.

FLUID trial: a hospital-wide open-label cluster cross-over pragmatic comparative effectiveness randomised pilot trial comparing normal saline to Ringer's lactate

OBJECTIVES

Normal saline (NS) and Ringer's lactate (RL) are the most common crystalloids used for fluid therapy. Despite evidence of possible harm associated with NS (eg, hyperchloremic metabolic acidosis, impaired kidney function and death), few large multi-centre randomised trials have evaluated the effect of these fluids on clinically important outcomes. We conducted a pilot trial to explore the feasibility of a large trial powered for clinically important outcomes.

DESIGN

FLUID was a pragmatic pilot cluster randomised cross-over trial.

SETTING

Four hospitals in the province of Ontario, Canada PARTICIPANTS: All hospitalised adult and paediatric patients with an incident admission to the hospital over the course of each study period.

INTERVENTIONS

A hospital wide policy/strategy which stocked either NS or RL throughout the hospital for 12 weeks before crossing over to the alternate fluid for the subsequent 12 weeks.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary feasibility outcome was study fluid protocol adherence. Secondary feasibility outcomes included time to Research Ethics Board (REB) approval and trial initiation. Primary (composite of death or re-admission to hospital in first 90 days of index hospitalisation) and secondary clinical outcomes were analysed descriptively.

RESULTS

Among 24 905 included patients, mean age 59.1 (SD 20.5); 13 977 (56.1%) were female and 21 150 (85.0%) had medical or surgical admitting diagnoses. Overall, 96 821 L were administered in the NS arm, and 78 348 L in the RL arm. Study fluid adherence to NS and RL was 93.7% (site range: 91.6%-98.0%) and 79.8% (site range: 72.5%-83.9%), respectively. Time to REB approval ranged from 2 to 48 days and readiness for trial initiation from 51 to 331 days. 5544 (22.3%) patients died or required hospital re-admission in the first 90 days.

CONCLUSIONS

The future large trial is feasible. Anticipating and addressing logistical challenges during the planning stages will be imperative.

TRIAL REGISTRATION NUMBER

NCT02721485.

Nomogram Prediction Model of Serum Chloride and Sodium Ions on the Risk of Acute Kidney Injury in Critically Ill Patients

Purpose

This study aims to investigate the effect of serum chloride and sodium ions on AKI occurrence in ICU patients, and further constructs a prediction model containing these factors to explore the predictive value of these ions in AKI.

Methods

The clinical information of patients admitted to ICU of Beijing Friendship Hospital Affiliated to Capital Medical University was collected for retrospective analysis. Logistic regression analysis was used to analyzing the influencing factors. A nomogram for predicting AKI risk was constructed with R software and validated by repeated sampling. Afterwards, the effectiveness and accuracy of the model were tested and evaluated.

Results

A total of 446 cases met the requirements of this study, of which 178 developed AKI during their stay in ICU, with an incidence rate of 39.9%. Hypernatremia, heart failure, sepsis, APACHE II score, and initial creatinine value and BE value at ICU admission before the diagnosis of AKI were identified as independent risk factors for developing AKI during ICU stay. These predictors were incorporated into the nomogram of AKI risk in critically ill patients, which was constructed by using R software. Receiver operating characteristic curve analysis was further used and showed that the area under the curve of the model was 0.7934 (95% CI 0.742–0.8447), indicating that the model had an ideal value. Finally, further evaluated its clinical effectiveness. The clinical effect curve and decision curve showed that most areas of the decision curve of this model were greater than 0, indicating that this model owned a certain clinical effectiveness.

Conclusion

The nomogram based on hypernatremia, heart failure, sepsis, APACHE II score, and initial creatinine and BE value in ICU can predict the individualized risk of AKI with satisfactory distinguishability and accuracy.

Electrolyte and Acid-Base Disturbances in Emergency High-Risk Abdominal Surgery, a Retrospective Study

BACKGROUND

Patients undergoing emergency high-risk abdominal surgery potentially suffer from both systemic dehydration and hypovolaemia. Data on the prevalence and clinical impact of electrolyte disturbances in this patient group, specifically the differences in patients with intestinal obstruction (IO) versus perforated viscus (PV) are lacking.

METHODS

Adult patients undergoing emergency high-risk abdominal surgery in a standardized perioperative pathway were included in this retrospective single-center cohort study. Electrolytes and arterial blood gas analysis were measured during the early perioperative period. Prevalence and clinical impact of electrolyte disturbances were assessed.

RESULTS

A total of 354 patients were included in the study. Preoperative alkalemia dominated preoperatively, significantly more prevalent in IO (45 vs. 32%, p < .001), while acidosis was most pronounced postoperatively in PV (49 vs. 28%, p < .0001). Preoperative hypochloraemia and hypokalemia were more frequent in the IO (34 vs. 20% and 37 vs. 25%, respectively). Hyponatremia was highly prevalent in both IO and PV. Pre- and postoperative hypochloremia were independently associated with 30-day postoperative morbidity and mortality in patients with IO (OR 2.87 (1.35, 6.23) p = 0.006, OR 6.86 (1.71, 32.2) p = 0.009, respectively). Hypochloremic patients presented with reduced long-term survival as compared with the normo- and hyperchloremic patients (p < 0.05). Neither plasma sodium nor potassium showed a significant association with outcome.

CONCLUSION

These observations suggest that acute high-risk abdominal patients have frequent preoperative alkalosis shifting to postoperative acidosis. Both pre- and postoperative hypochloremia were independently associated with both impaired short- and long-term outcome in patients with intestinal obstruction, with potential implications for the choice of resuscitations fluids.

Observational study on fluid therapy management in surgical adult patients

Background

Perioperative fluid therapy management is changing due to the incorporation of different fluids, surgical techniques, and minimally invasive monitoring systems. The objective of this study was to explore fluid therapy management during the perioperative period in our country.

Methods

We designed the Fluid Day study as a cross-sectional, multicentre, observational study. The study was performed in 131 Spanish hospitals in February 2019. We included adult patients undergoing general anaesthesia for either elective or non-elective surgery. Demographic variables were recorded, as well as the type and total volume of fluid administered during the perioperative period and the monitorization used. To perform the analysis, patients were categorized by risk group.

Results

We recruited 7291 patients, 6314 of which were included in the analysis; 1541 (24.4%) patients underwent high-risk surgery, 1497 (23. 7%) were high risk patients, and 554 (8.7%) were high-risk patients and underwent high-risk surgery; 98% patients received crystalloids (80% balanced solutions); intraoperative colloids were used in 466 patients (7.51%). The hourly intraoperative volume in mL/kg/h and the median [Q1; Q3] administered volume (mL/kg) were, respectively, 6.67 [3.83; 8.17] ml/Kg/h and 13.9 [9.52;5.20] ml/Kg in low-risk patients undergoing low- or intermediate-risk surgery, 6 [4.04; 9.08] ml/Kg/h and 15.7 [10.4;24.5] ml/Kg in high- risk patients undergoing low or intermediate-risk surgery, 6.41 [4.36; 9.33] ml/Kg/h and 20.2 [13.3;32.4] ml/Kg in low-risk patients undergoing high-risk surgery, and 5.46 [3.83; 8.17] ml/Kg/h and 22.7[14.1;40.9] ml/Kg in high-risk patients undergoing high- risk surgery . We used advanced fluid monitoring strategies in 5% of patients in the intraoperative period and in 10% in the postoperative period.

Conclusions

The most widely used fluid was balanced crystalloids. Colloids were used in a small number of patients. Hourly surgery volume tended to be more restrictive in high-risk patients but confirms a high degree of variation in the perioperatively administered volume. Scarce monitorization was observed in fluid therapy management.

Trial registration

Clinical Trials: NCT03630744.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01518-z.

Intravenous Fluid Selection for Unruptured Intracranial Aneurysm Clipping : Balanced Crystalloid versus Normal Saline

OBJECTIVE

While balanced crystalloid (BC) could be a relevant fluid regimen with buffer system compared with normal saline (NS), there have been no studies on the optimal fluid for surgery of an unruptured intracranial aneurysm (UIA). This study aimed to compare the effects of fluid regimens between NS and BC on the metabolic and clinical outcomes of patients who underwent surgery for UIA.

METHODS

This study was designed as a propensity score matched retrospective comparative study and included adult patients who underwent UIA clipping. Patient groups were categorized as NS and BC groups based on the types of pre-operative fluid and the amount of fluid administered during surgery. The primary outcomes were defined as electrolyte imbalance and acidosis immediately after surgery. The secondary outcomes were the length of stay in the intensive care unit (ICU) and duration from the end of the operation to extubation.

RESULTS

A total of 586 patients were enrolled in this study, with each of 293 patients assigned to the NS and BC groups, respectively. Immediately after surgery, serum chloride levels were significantly higher in the NS group. Compared to the NS group, the BC group had lower incidence rates of acidemia (6.5% vs. 11.6%, p=0.043) and metabolic acidosis (0.7% vs. 4.4%, p=0.007). As compared to NS group, BC group had significantly shorter duration from the end of the operation to extubation (250±824 vs. 122±372 minutes, p=0.016) and length of stay in ICU (1.37±1.11 vs. 1.12±0.61 days, p=0.001). Throughout multivariable analysis, use of BC was found to be significant factor for favorable post-operative results.

CONCLUSION

This study showed that the patients who received BC during UIA clipping had lower incidence of metabolic acidosis, earlier extubation and shorter ICU stay compared to those who received NS. Therefore, using BC as a peri-operative fluid can be recommended for patients who undergo surgery for UIA.

Effect of 0.9% NaCl compared to plasma-lyte on biomarkers of kidney injury, sodium excretion and tubular transport proteins in patients undergoing primary uncemented hip replacement - a randomized trial

Background

Isotonic saline (IS) is widely used to secure perioperative cardiovascular stability. However, the high amount of chloride in IS can induce hyperchloremic acidosis. Therefore, IS is suspected to increase the risk of acute kidney injury (AKI). Biomarkers may have potential as indicators.

Methods

In a double-blinded, placebo-controlled study, 38 patients undergoing primary uncemented hip replacement were randomized to IS or PlasmaLyte (PL). Infusion was given during surgery as 15 ml/kg the first hour and 5 ml/kg the following two hours. Urinary samples were collected upon admission and the day after surgery. As surgery was initiated, urine was collected over the course of 4 h. Hereafter, another urine collection proceeded until the morning. Urine was analyzed for markers of AKI neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1). Arterious and venous blood samples for measurements of pH and plasma electrolytes including chloride (p-Cl) were collected as surgery was initiated, at the end of surgery and the following morning.

Results

IS induced an increase in p-Cl (111 ± 2 mmol/L after IS and 108 ± 3 after PL, p = 0.004) and a decrease in pH (7.39 ± 0.02 after IS and 7.43 ± 0.03 after PL, p = 0.001). Urinary NGAL excretion increased in both groups (ΔNGAL: 5.5 [4.1; 11.7] μg/mmol creatinine p = 0.004 after IS vs. 5.5 [2.1;9.4] μg/mmol creatinine after PL, p < 0.001). No difference was found between the groups (p = 0.839). Similarly, urinary KIM-1 excretion increased in both groups (ΔKIM-1: IS 115.8 [74.1; 156.2] ng/mmol creatinine, p < 0.001 vs. PL 152.4 [120.1; 307.9] ng/mmol creatinine, p < 0.001). No difference between the groups (p = 0.064).

FE_Na increased (1.08 ± 0.52% after IS and 1.66 ± 1.15% after PL, p = 0.032). ENaC excretion was different within groups (p = 0.019).

Conclusion

A significantly higher plasma chloride and a lower pH was present in the group receiving isotonic saline. However, u-NGAL and u-KIM-1 increased significantly in both groups after surgery despite absence of changes in creatinine. These results indicate that surgery induced subclinical kidney injury. Also, the IS group had a delayed sodium excretion as compared to the PL group which may indicate that IS affects renal sodium excretion differently from PL.

Trial registration

ClinicalTrials.gov Identifier: NCT02528448, 19/08/2015

Impact of a new balanced gelatine on electrolytes and pH in the perioperative care

INTRODUCTION

Balanced fluid replacement solutions can possibly reduce the risks for electrolyte imbalances, for acid-base imbalances, and thus for renal failure. To assess the intraoperative change of base excess (BE) and chloride in serum after treatment with either a balanced gelatine/electrolyte solution or a non-balanced gelatine/electrolyte solution, a prospective, controlled, randomized, double-blind, dual centre phase III study was conducted in two tertiary care university hospitals in Germany.

MATERIAL AND METHODS

40 patients of both sexes, aged 18 to 90 years, who were scheduled to undergo elective abdominal surgery with assumed intraoperative volume requirement of at least 15 mL/kg body weight gelatine solution were included. Administration of study drug was performed intravenously according to patients need. The trigger for volume replacement was a central venous pressure (CVP) minus positive end-expiratory pressure (PEEP) <10 mmHg (CVP <10 mmHg). The crystalloid:colloid ratio was 1:1 intra- and postoperatively. The targets for volume replacement were a CVP between 10 and 14 mmHg minus PEEP after treatment with vasoactive agent and mean arterial pressure (MAP) > 65 mmHg.

RESULTS

The primary endpoints, intraoperative changes of base excess -2.59 ± 2.25 (median: -2.65) mmol/L (balanced group) and -4.79 ± 2.38 (median: -4.70) mmol/L (non-balanced group)) or serum chloride 2.4 ± 1.9 (median: 3.0) mmol/L and 5.2 ± 3.1 (median: 5.0) mmol/L were significantly different (p = 0.0117 and p = 0.0045, respectively). In both groups (each n = 20) the investigational product administration in terms of volume and infusion rate was comparable throughout the course of the study, i.e. before, during and after surgery.

DISCUSSION

Balanced gelatine solution 4% combined with a balanced electrolyte solution demonstrated significant smaller impact on blood gas analytic parameters in the primary endpoints BE and serum chloride when compared to a non-balanced gelatine solution 4% combined with NaCl 0.9%. No marked treatment differences were observed with respect to haemodynamics, coagulation and renal function.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01515397) and clinicaltrialsregister.eu, EudraCT number 2010-018524-58.

Optimal crystalloid volume ratio for blood replacement for maintaining hemodynamic stability and lung function: an experimental randomized controlled study

BACKGROUND

Crystalloids are first line in fluid resuscitation therapy, however there is a lack of evidence-based recommendations on the volume to be administered. Therefore, we aimed at comparing the systemic hemodynamic and respiratory effects of volume replacement therapy with a 1:1 ratio to the historical 1:3 ratio.

METHODS

Anesthetized, ventilated rats randomly included in 3 groups: blood withdrawal and replacement with crystalloid in 1:1 ratio (Group 1, n = 11), traditional 1:3 ratio (Group 3, n = 12) and a control group with no interventions (Group C, n = 9). Arterial blood of 5% of the total blood volume was withdrawn 7 times, and replaced stepwise with different volume rations of Ringer's acetate, according to group assignments. Airway resistance (Raw), respiratory tissue damping (G) and tissue elastance (H), mean arterial pressure (MAP) and heart rate (HR) were assessed following each step of fluid replacement with a crystalloid (CR1-CR6). Lung edema index was measured from histological samples.

RESULTS

Raw decreased in Groups 1 and 3 following CR3 (p < 0.02) without differences between the groups. H elevated in all groups (p < 0.02), with significantly higher changes in Group 3 compared to Groups C and 1 (both p = 0.03). No differences in MAP or HR were present between Groups 1 and 3. Lung edema was noted in Group 3 (p < 0.05).

CONCLUSIONS

Fluid resuscitation therapy by administering a 1:1 blood replacement ratio revealed adequate compensation capacity and physiological homeostasis similar with no lung stiffening and pulmonary edema. Therefore, considering this ratio promotes the restrictive fluid administration in the presence of continuous and occult bleeding.

"I don't get no respect": the role of chloride in acute kidney injury

Acute kidney injury (AKI) is a major public health problem that complicates 10-40% of hospital admissions. Importantly, AKI is independently associated with increased risk of progression to chronic kidney disease, end-stage renal disease, cardiovascular events, and increased risk of in-hospital and long-term mortality. The chloride content of intravenous fluid has garnered much attention over the last decade, as well as its association with excess use and adverse outcomes, including AKI. Numerous studies show that changes in serum chloride concentration, independent of serum sodium and bicarbonate, are associated with increased risk of AKI, morbidity, and mortality. This comprehensive review details the complex renal physiology regarding the role of chloride in regulating renal blood flow, glomerular filtration rate, tubuloglomerular feedback, and tubular injury, as well as the findings of clinical research related to the chloride content of intravenous fluids, changes in serum chloride concentration, and AKI. Chloride is underappreciated in both physiology and pathophysiology. Although the exact mechanism is debated, avoidance of excessive chloride administration is a reasonable treatment option for all patients and especially in those at risk for AKI. Therefore, high-risk patients and those with "incipient" AKI should receive balanced solutions rather than normal saline to minimize the risk of AKI.

FLUID trial: a protocol for a hospital-wide open-label cluster crossover pragmatic comparative effectiveness randomised pilot trial

INTRODUCTION

0.9% saline and Ringer's lactate are the two most common resuscitation crystalloid fluids. 0.9% saline may lead to hyperchloraemic metabolic acidosis and may be associated with impaired kidney function and death. Few large multicentre randomised trials have been conducted to evaluate the effect of these two fluids on clinically important outcomes.

METHODS

FLUID is a pragmatic pilot cluster randomised crossover trial in which four hospitals will be randomised to normal saline or Ringer's lactate for 14 weeks, then crossover to the alternative fluid for the subsequent 14 weeks after 1 to 3 week transition. With waiver of informed consent, all adult and paediatric patients admitted to participating sites will be included in the FLUID trial except for neonates. Primary feasibility outcome is study fluid protocol adherence (target:≥80%). Secondary feasibility outcomes include time to research ethics board (REB) approval and readiness to trial initiation (≤3 months from REB submission and approval). Primary (composite of death or re-admission to hospital in first 90 days of index hospitalisation) and secondary clinical outcomes for the future large FLUID trial will be described. Protocol adherence will be collected by site at specified time points. All clinical data will be obtained at patient level through provincial health administrative data held at the Institute for Clinical Evaluative Sciences (ICES). Event rates for the primary and secondary outcomes will be described using frequencies and proportions with 95% CIs. Intracluster and interperiod correlation coefficients will be calculated from population-level data available at ICES.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Ottawa Health Science Research Ethics Board. The FLUID pilot will determine feasibility, and ICES data across all potential sites in Ontario will allow calculation of sample size parameter estimates to inform the design and implementation of the large trial.

TRIAL REGISTRATION NUMBER

NCT02721485; Pre-results.

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.

The crashing patient: hemodynamic collapse

PURPOSE OF REVIEW

Rapid restoration of tissue perfusion and oxygenation are the main goals in the resuscitation of a patient with circulatory collapse. This review will focus on providing an evidence based framework of the technological and conceptual advances in the evaluation and management of the patient with cardiovascular collapse.

RECENT FINDINGS

The initial approach to the patient in cardiovascular collapse continues to be based on the Ventilate-Infuse-Pump rule. Point of care ultrasound is the preferred modality for the initial evaluation of undifferentiated shock, providing information to narrow the differential diagnosis, to assess fluid responsiveness and to evaluate the response to therapy. After the initial phase of resuscitative fluid administration, which focuses on re-establishing a mean arterial pressure to 65 mmHg, the use of dynamic parameters to assess preload responsiveness such as the passive leg raise test, stroke volume variation, pulse pressure variation and collapsibility of the inferior vena cava in mechanically ventilated patients is recommended.

SUMMARY

The crashing patient remains a clinical challenge. Using an integrated approach with bedside ultrasound, dynamic parameters for the evaluation of fluid responsiveness and surrogates of evaluation of tissue perfusion have made the assessment of the patient in shock faster, safer and more physiologic.

Common Sense Approach to Managing Sepsis

Sepsis results in many deaths, prolonged suffering among survivors and relatives, and high use of resources both in developed and developing countries. The updated Surviving Sepsis Campaign guidelines should aid clinicians in improving the identification and management of these patients, but many uncertainties remain because most of the guidance is based on low-quality evidence. This article discusses how to use some of the specific items of the guidelines together with a common-sense approach to aid clinical management of patients with sepsis while trying to balance the potential benefit and harm of the items.

Perioperative administration of buffered versus non-buffered crystalloid intravenous fluid to improve outcomes following adult surgical procedures

BACKGROUND

Perioperative fluid strategies influence clinical outcomes following major surgery. Many intravenous fluid preparations are based on simple solutions, such as normal saline, that feature an electrolyte composition that differs from that of physiological plasma. Buffered fluids have a theoretical advantage of containing a substrate that acts to maintain the body's acid-base status - typically a bicarbonate or a bicarbonate precursor such as maleate, gluconate, lactate, or acetate. Buffered fluids also provide additional electrolytes, including potassium, magnesium, and calcium, more closely matching the electrolyte balance of plasma. The putative benefits of buffered fluids have been compared with those of non-buffered fluids in the context of clinical studies conducted during the perioperative period. This review was published in 2012, and was updated in 2017.

OBJECTIVES

To review effects of perioperative intravenous administration of buffered versus non-buffered fluids for plasma volume expansion or maintenance, or both, on clinical outcomes in adults undergoing all types of surgery.

SEARCH METHODS

We electronically searched the Clinicaltrials.gov major trials registry, the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 6) in the Cochrane Library, MEDLINE (1966 to June 2016), Embase (1980 to June 2016), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to June 2016). We handsearched conference abstracts and, when possible, contacted leaders in the field. We reran the search in May 2017. We added one potential new study of interest to the list of 'Studies awaiting classification' and will incorporate this trial into formal review findings when we prepare the review update.

SELECTION CRITERIA

Only randomized controlled trials that compared buffered versus non-buffered intravenous fluids for surgical patients were eligible for inclusion. We excluded other forms of comparison such as crystalloids versus colloids and colloids versus different colloids.

DATA COLLECTION AND ANALYSIS

Two review authors screened references for eligibility, extracted data, and assessed risks of bias. We resolved disagreements by discussion and consensus, in collaboration with a third review author. We contacted trial authors to request additional information when appropriate. We presented pooled estimates for dichotomous outcomes as odds ratios (ORs) and for continuous outcomes as mean differences (MDs), with 95% confidence intervals (CIs). We analysed data via Review Manager 5.3 using fixed-effect models, and when heterogeneity was high (I² > 40%), we used random-effects models.

MAIN RESULTS

This review includes, in total, 19 publications of 18 randomized controlled trials with a total of 1096 participants. We incorporated five of those 19 studies (330 participants) after the June 2016 update. Outcome measures in the included studies were thematically similar, covering perioperative electrolyte status, renal function, and acid-base status; however, we found significant clinical and statistical heterogeneity among the included studies. We identified variable protocols for fluid administration and total volumes of fluid administered to patients intraoperatively. Trial authors variably reported outcome data at disparate time points and with heterogeneous patient groups. Consequently, many outcome measures are reported in small group sizes, reducing overall confidence in effect size, despite relatively low inherent bias in the included studies. Several studies reported orphan outcome measures. We did not include in the results of this review one large, ongoing study of saline versus Ringer's solution.We found insufficient evidence on effects of fluid therapies on mortality and postoperative organ dysfunction (defined as renal insufficiency leading to renal replacement therapy); confidence intervals were wide and included both clinically relevant benefit and harm: mortality (Peto OR 1.85, 95% CI 0.37 to 9.33; I² = 0%; 3 trials, 6 deaths, 276 participants; low-quality evidence); renal insufficiency (OR 0.82, 95% CI 0.34 to 1.98; I² = 0%; 4 trials, 22 events, 276 participants; low-quality evidence).We noted several metabolic differences, including a difference in postoperative pH measured at end of surgery of 0.05 units - lower in the non-buffered fluid group (12 studies with a total of 720 participants; 95% CI 0.04 to 0.07; I² = 61%). However, this difference was not maintained on postoperative day one. We rated the quality of evidence for this outcome as moderate. We observed a higher postoperative serum chloride level immediately after operation, with use of non-buffered fluids reported in 10 studies with a total of 530 participants (MD 6.77 mmol/L, 95% CI 3.38 to 10.17), and this difference persisted until day one postoperatively (five studies with a total of 258 participants; MD 8.48 mmol/L, 95% CI 1.08 to 15.88). We rated the quality of evidence for this outcome as moderate.

AUTHORS' CONCLUSIONS

Current evidence is insufficient to show effects of perioperative administration of buffered versus non-buffered crystalloid fluids on mortality and organ system function in adult patients following surgery. Benefits of buffered fluid were measurable in biochemical terms, particularly a significant reduction in postoperative hyperchloraemia and metabolic acidosis. Small effect sizes for biochemical outcomes and lack of correlated clinical follow-up data mean that robust conclusions on major morbidity and mortality associated with buffered versus non-buffered perioperative fluid choices are still lacking. Larger studies are needed to assess these relevant clinical outcomes.

Balanced versus isotonic saline resuscitation-a systematic review and meta-analysis of randomized controlled trials in operation rooms and intensive care units

BACKGROUND

Fluid resuscitation is the cornerstone in treatment of shock, and intravenous fluid administration is the most frequent intervention in operation rooms and intensive care units (ICUs). The composition of fluids used for fluid resuscitation gained interest over the past decade, with recent focus on whether balanced solutions should be preferred over isotonic saline.

METHODS

Systematic review and meta-analysis of randomized controlled trials (RCTs) comparing fluid resuscitation with a balanced solution versus isotonic saline in adult patients in operation room or ICUs. Primary outcome was in-hospital mortality, secondary outcomes included occurrence of acute kidney injury (AKI) and need for renal replacement therapy (RRT).

RESULTS

The search identified 11 RCTs involving 2,703 patients; 8 trials were conducted in operation room and 3 in ICU. In-hospital mortality, as well as the occurrence of AKI and need for RRT was not different between resuscitation with balanced solutions versus isotonic saline, neither in operation room nor in ICU patients. Serum chloride levels, but not arterial pH, were significantly lower in patients resuscitated with balanced solutions.

CONCLUSIONS

Currently evidence insufficiently supports the use of balanced over isotonic saline for fluid resuscitation to improve outcome of operation room and ICU patients.

Changes from 2012 to 2015 in intravenous fluid solutions issued to hospital departments

BACKGROUND

In recent years, large trials have increased the level of evidence for intravenous (IV) fluid therapy, at least in the intensive care setting. It is less clear whether this change in the evidence base has been associated with changes in IV fluid use in different hospital departments.

METHODS

We obtained details from the regional pharmacy regarding IV fluids issued to hospital departments in the Danish Capitol Region from January 2012 to May 2015. We used paired Wilcoxon's signed-rank test to analyse changes in the issuing in different departments.

RESULTS

Total regional issuing of IV fluids showed increase in crystalloid solutions (9%; P = 0.001) and decrease in colloid solutions (59%; P = 0.005). Subtype analysis showed increased issuing of buffered crystalloids (36%; P = 0.001), human albumin (30%; P < 0.0001) and decreased issuing in synthetic colloid solutions (82%; P < 0.0001) from Q1 2012 to Q2 2015. At the departmental level, the issuing of synthetic colloid solutions decreased markedly to all settings. The issuing of buffered crystalloids increased to orthopaedic (226%; P = 0.03) and to general surgery departments (686%; P = 0.002). Albumin solutions were increasingly issued to anaesthesia departments (63%; P = 0.005) and was rarely issued to general surgery and orthopaedic departments.

CONCLUSIONS

The issuing of IV fluid solutions to hospital departments has changed markedly over the last years to less colloid, in particular the synthetic solutions, and relatively more issuing of crystalloids, in particular the buffered solutions.

Chloride alterations in hospitalized patients: Prevalence and outcome significance

Serum Cl (sCl) alterations in hospitalized patients have not been comprehensively studied in recent years. The aim of this study is to investigate the prevalence and outcome significance of (1) sCl alterations on hospital admission, and (2) sCl evolution within the first 48 hr of hospital admission. We conducted a retrospective study of all hospital admissions in the years 2011–2013 at Mayo Clinic Rochester, a 2000-bed tertiary medical center. Outcome measures included hospital mortality, length of hospital stay and discharge disposition. 76,719 unique admissions (≥18 years old) were studied. Based on hospital mortality, sCl in the range of 105–108 mmol/L was found to be optimal. sCl <100 (n = 13,611) and >108 (n = 11,395) mmol/L independently predicted a higher risk of hospital mortality, longer hospital stay and being discharged to a care facility. 13,089 patients (17.1%) had serum anion gap >12 mmol/L; their hospital mortality, when compared to 63,630 patients (82.9%) with anion gap ≤12 mmol/L, was worse. Notably, patients with elevated anion gap displayed a progressively worsening mortality with rising sCl. sCl elevation within 48 hr of admission was associated with a higher proportion of 0.9% saline administration and was an independent predictor for hospital mortality. Moreover, the magnitude of sCl rise was inversely correlated to the days of patient survival. In conclusion, serum Cl alterations on admission predict poor clinical outcomes. Post-admission sCl increase, due to Cl-rich fluid infusion, independently predicts hospital mortality. These results raise a critical question of whether iatrogenic cause of hyperchloremia should be avoided, a question to be addressed by future prospective studies.

Acetate-buffered crystalloid infusate versus infusion of 0.9% saline and hemodynamic stability in patients undergoing renal transplantation : Prospective, randomized, controlled trial

Background

Infusion therapy is one of the most frequently prescribed medications in hospitalized patients. Currently used crystalloid solutes have a variable composition and may therefore influence acid-base status, intracellular and extracellular water content and plasma electrolyte compositions and have a major impact on organ function and outcome. The aim of our study was to investigate whether use of acetate-based balanced crystalloids leads to better hemodynamic stability compared to 0.9% saline.

Methods

We performed a sub-analysis of a prospective, randomized, controlled trial comparing effects of 0.9% saline or an acetate-buffered, balanced crystalloid during the perioperative period in patients with end-stage renal disease undergoing cadaveric renal transplantation. Need for catecholamine therapy and blood pressure were the primary measures.

Results

A total of 150 patients were included in the study of which 76 were randomized to 0.9% saline while 74 received an acetate-buffered balanced crystalloid. Noradrenaline for cardiocirculatory support during surgery was significantly more often administered in the normal saline group, given earlier and with a higher cumulative dose compared to patients receiving an acetate-buffered balanced crystalloid (30% versus 15%, p = 0.027; 68 ± 45 µg/kg versus 75 ± 60 µg/kg, p = 0.0055 and 0.000492 µg/kg body weight/min, ±0.002311 versus 0.000107 µg/kg/min, ±0.00039, p = 0.04, respectively). Mean minimum arterial blood pressure was significantly lower in patients randomized to 0.9% saline than in patients receiving the balanced infusion solution (57.2 [SD 8.7] versus 60.3 [SD 10.2] mm Hg, p = 0.024).

Conclusion

The use of an acetate-buffered, balanced infusion solution results in reduced need for use of catecholamines and cumulative catecholamine dose for hemodynamic support and in less occurrence of arterial hypotension in the perioperative period. Further research in the field is strongly encouraged.

Resuscitation fluid composition affects hepatic inflammation in a murine model of early sepsis

BACKGROUND

Fluid resuscitation is a crucial therapy for sepsis, and the use of balanced fluids and/or isotonic albumin may improve patient survival. We have previously demonstrated that resuscitation with normal saline results in increased hepatic leukocyte recruitment in a murine model of sepsis. Given that clinical formulations of albumin are in saline, our objectives were to develop a novel balanced electrolyte solution specifically for sepsis and to determine if supplementing this solution with albumin would improve the inflammatory response in sepsis.

METHODS

We developed two novel buffered electrolyte solutions that contain different concentrations of acetate and gluconate, named Seplyte L and Seplyte H, and administered these solutions with or without 5% albumin. Normal saline with or without albumin and Ringer's lactate served as controls. Sepsis was induced by cecal ligation and puncture (CLP), and the liver microvasculature was imaged in vivo at 6 h after CLP to quantify leukocyte recruitment. Hepatic cytokine expression and plasma cell-free DNA (cfDNA) concentrations were also measured.

RESULTS

Septic mice receiving either Seplyte fluid showed significant reductions in hepatic post-sinusoidal leukocyte rolling and adhesion compared to normal saline. Hepatic cytokine concentrations varied in response to different concentrations of acetate and gluconate in the novel resuscitation fluids but were unaffected by albumin. All Seplyte fluids significantly increased hepatic TNF-α levels at 6 h compared to control fluids. However, Seplyte H exhibited a similar cytokine profile to the control fluids for all other cytokines, whereas mice given Seplyte L had significantly elevated IL-6, IL-10, KC (CXCL1), and MCP-1 (CCL2). Plasma cfDNA was generally increased during sepsis, but resuscitation fluid composition did not significantly affect cfDNA concentrations.

CONCLUSIONS

Electrolyte concentrations and buffer constituents of resuscitation fluids can modulate hepatic cytokine production and leukocyte recruitment in septic mice, while the effects of albumin are modest during early sepsis. Therefore, crystalloid fluid choice should be an important consideration for resuscitation in sepsis, and the effects of fluid composition on inflammation in other organ systems should be studied to better understand the physiological impact of this vital sepsis therapy.

Fast-track Orthognathic Surgery: An Evidence-based Review

The aim of this study was to establish a fast-track protocol for bimaxillary orthognathic surgery (OGS). Fast-track surgery (FTS) is a multidisciplinary approach where the pre-, intra-, and postoperative management is focusing maximally on a quick patient recovery and early discharge. To enable this, the patients' presurgical stress and postsurgical discomfort should be maximally reduced. Both referral patterns and expenses within the health-care system are positively influenced by FTS. University hospital-literature review through Medline, Embase, and the Cochrane Library (January 2000-July 2016) using the following words - "fast track, enhanced recovery, multimodal, and perioperative care" - to define a protocol evidence based for OGS, as well as evidenced-based medicine search of every term added to the protocol during the same period. The process has resulted in an OGS protocol that may improve the outcome of the patient through several nonoperative and operative measures such as preoperative patient education and intra/postoperative measures that should improve overall patient satisfaction, decrease morbidity such as postoperative nausea, headache, dizziness, pain, and intubation discomfort, and shorten hospital stay. A literature review allowed us to fine-tune a fast-track protocol for uncomplicated OGS that can be prospectively studied against currently applied ones.

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.

Fluid loading in abdominal surgery - saline versus hydroxyethyl starch (FLASH Trial): study protocol for a randomized controlled trial

Background

Inappropriate fluid therapy during surgery is associated with significant morbidity and mortality. Few studies have examined the effects of particular types of fluids (crystalloid or colloid solutions) in surgical patients, especially with the goal of hemodynamic optimization. Isotonic saline is the most commonly used fluid worldwide but may be associated with potential nephrotoxicity. Hydroxyethyl starch (HES) solutions are widely used in surgical patients as a component of goal-directed fluid optimization strategies, but several large multicenter studies have suggested increased rates of acute kidney injury and adverse events with the use of HES in ICU patients. Despite what may be inferred from physiological studies, the benefit and harm of 0.9 % saline and HES during hemodynamic therapy have not been clearly established in surgical patients.

Methods/Design

The FLASH trial is an investigator-initiated, prospective, multicenter, randomized, double-blinded, two-arm trial, randomizing 826 patients with moderate-to-high risk of postoperative complications to receive 6 % HES 130/0.4 or 0.9 % saline during individualized goal-directed fluid optimization. The primary outcome measure is a composite of death or major postoperative complications within 14 days following surgery.

The sample size will allow the detection of a 10 % absolute between-group difference in the primary outcome measure with a type 1 error rate of 5 % and power of 95 %, assuming a 5 % mortality rate and 20 % morbidity (thus 25 % for the composite endpoint).

Discussion

The FLASH trial may provide important data on the efficacy and safety of commonly used fluid solutions and could have a significant impact on future treatment of surgical patients.

Trial registration

ClinicalTrials.gov Identifier: NCT02502773. Registered 16 June 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-1085-3) contains supplementary material, which is available to authorized users.

A porcine polytrauma model with two different degrees of hemorrhagic shock: outcome related to trauma within the first 48 h

BACKGROUND

An animal polytrauma model was developed, including trunk and extremity injuries combined with hemorrhagic shock and a prolonged post-traumatic phase. This could be useful for the assessment of different therapeutic approaches during intensive care therapy.

METHODS

A standardized polytrauma including lung contusion, liver laceration and lower leg fracture was applied in 25 pigs. They underwent controlled haemorrhage either with a blood volume loss of 45 % and a median arterial pressure (MAP) <30 mmHg/90 min (group L, n = 15) or a 50 % blood loss of and an MAP <25 mmHg/120 min (group H, n = 10). Five non-traumatized pigs served as a control (group C). Subsequently, intensive care treatment was given for an observational period of 48 h.

RESULTS

Both trauma groups showed signs of shock and organ injury (heart rate, MAP and lactate). The frequency of cardiopulmonary resuscitation (CPR) and lung injury was directly related to the severity of the haemorrhagic shock (CPR-group L: 4 of 15 pigs, group H: 4 of 10 pigs; Respiratory failure-group L: 3 of 13, group H: 3 of 9. There was no difference in mortality between trauma groups.

CONCLUSION

The present data suggest that our model reflects the mortality and organ failure of polytrauma in humans during shock and the intensive care period. This suggests that the experimental protocol could be useful for the assessment of therapeutic approaches during the post-traumatic period.

[Choice of crystalloids in interventions and surgery]

BACKGROUND

Fluid therapy is daily routine in the perioperative setting; however, high quality guidelines are lacking. The S3-guideline Intravasal Fluid Therapy in the Adult Patient gives evidence- and consensus-based recommendations for the use of fluids in perioperative and critically ill patients. In addition to identifying hypovolemia and guiding volume replacement, the type of fluid that should be used is addressed.

OBJECTIVES

The purpose of this article is to present and discuss the recommendations of the S3-guideline with respect to the choice of crystalloids in the perioperative setting.

MATERIALS AND METHODS

A literature search within the scope of the guideline development was performed.

RESULTS AND CONCLUSIONS

In this review the recommendations and their rationale in the perioperative setting are presented. Crystalloids are the basis of fluid therapy. Instead of isotonic saline, buffered solutions are recommended. Regarding the type of buffer (lactate, acetate, malate), no preferences based on outcome data can be made.

[Dos and don'ts for crystalloids in intensive care medicine. Can too much water be bad?]

Notwithstanding the use of colloids, crystalloids have a firm position in today's intensive care: In addition to the substitution as a basic requirement of the human organism or drug carriers, they are primarily used for volume replacement. A common complication is the development of interstitial edema, which is due to the composition of these solutions and the permeability of the glycocalyx.With the large variety available on the market, bicarbonate-based precursor isotonic-balanced full electrolyte solutions have become established in the meantime. The use of 0.9% saline solution is regarded as obsolete. With low cost and a good safety profile, a few relevant aspects, e.g., the risk of hypervolemia and electrolyte imbalance, must be taken into account in the use of crystalloids.

Treatment of acute non-anion gap metabolic acidosis

Acute non-anion gap metabolic acidosis, also termed hyperchloremic acidosis, is frequently detected in seriously ill patients. The most common mechanisms leading to this acid-base disorder include loss of large quantities of base secondary to diarrhea and administration of large quantities of chloride-containing solutions in the treatment of hypovolemia and various shock states. The resultant acidic milieu can cause cellular dysfunction and contribute to poor clinical outcomes. The associated change in the chloride concentration in the distal tubule lumen might also play a role in reducing the glomerular filtration rate. Administration of base is often recommended for the treatment of acute non-anion gap acidosis. Importantly, the blood pH and/or serum bicarbonate concentration to guide the initiation of treatment has not been established for this type of metabolic acidosis; and most clinicians use guidelines derived from studies of high anion gap metabolic acidosis. Therapeutic complications resulting from base administration such as volume overload, exacerbation of hypertension and reduction in ionized calcium are likely to be as common as with high anion gap metabolic acidosis. On the other hand, exacerbation of intracellular acidosis due to the excessive generation of carbon dioxide might be less frequent than in high anion gap metabolic acidosis because of better tissue perfusion and the ability to eliminate carbon dioxide. Further basic and clinical research is needed to facilitate development of evidence-based guidelines for therapy of this important and increasingly common acid-base disorder.

Choices in fluid type and volume during resuscitation: impact on patient outcomes

We summarize the emerging new literature regarding the pathophysiological principles underlying the beneficial and deleterious effects of fluid administration during resuscitation, as well as current recommendations and recent clinical evidence regarding specific colloids and crystalloids. This systematic review allows us to conclude that there is no clear benefit associated with the use of colloids compared to crystalloids and no evidence to support the unique benefit of albumin as a resuscitation fluid. Hydroxyethyl starch use has been associated with increased acute kidney injury (AKI) and use of renal replacement therapy. Other synthetic colloids (dextran and gelatins) though not well studied do not appear superior to crystalloids. Normal saline (NS) use is associated with hyperchloremic metabolic acidosis and increased risk of AKI. This risk is decreased when balanced salt solutions are used. Balanced crystalloid solutions have shown no harmful effects, and there is evidence for benefit over NS. Finally, fluid resuscitation should be applied in a goal-directed manner and targeted to physiologic needs of individual patients. The evidence supports use of fluids in volume-responsive patients whose end-organ perfusion parameters have not been met.

Meta-analysis of high- versus low-chloride content in perioperative and critical care fluid resuscitation

Background

The objective of this systematic review and meta-analysis was to assess the relationship between the chloride content of intravenous resuscitation fluids and patient outcomes in the perioperative or intensive care setting.

Methods

Systematic searches were performed of PubMed/MEDLINE, Embase and Cochrane Library (CENTRAL) databases in accordance with PRISMA guidelines. Randomized clinical trials, controlled clinical trials and observational studies were included if they compared outcomes in acutely ill or surgical patients receiving either high-chloride (ion concentration greater than 111 mmol/l up to and including 154 mmol/l) or lower-chloride (concentration 111 mmol/l or less) crystalloids for resuscitation. Endpoints examined were mortality, measures of kidney function, serum chloride, hyperchloraemia/metabolic acidosis, blood transfusion volume, mechanical ventilation time, and length of hospital and intensive care unit stay. Risk ratios (RRs), mean differences (MDs) or standardized mean differences (SMDs) and confidence intervals were calculated using fixed-effect modelling.

Results

The search identified 21 studies involving 6253 patients. High-chloride fluids did not affect mortality but were associated with a significantly higher risk of acute kidney injury (RR 1·64, 95 per cent c.i. 1·27 to 2·13; P < 0·001) and hyperchloraemia/metabolic acidosis (RR 2·87, 1·95 to 4·21; P < 0·001). High-chloride fluids were also associated with greater serum chloride (MD 3·70 (95 per cent c.i. 3·36 to 4·04) mmol/l; P < 0·001), blood transfusion volume (SMD 0·35, 0·07 to 0·63; P = 0·014) and mechanical ventilation time (SMD 0·15, 0·08 to 0·23; P < 0·001). Sensitivity analyses excluding heavily weighted studies resulted in non-statistically significant effects for acute kidney injury and mechanical ventilation time.

Conclusion

A weak but significant association between higher chloride content fluids and unfavourable outcomes was found, but mortality was unaffected by chloride content.

Fluid therapy in critical illness

Major surgery and critical illnesses such as sepsis and trauma all disturb normal physiological fluid handling. Intravenous fluid therapy for resuscitation and fluid maintenance is a central part of medical care during these conditions, yet the evidence base supporting practice in this area lacks answers to a number of important questions. Recent research developments include a refinement of our knowledge of the endothelial barrier structure and function and a focus on the potential harm that may be associated with intravenous fluid therapy. Here, we briefly describe the contemporary view of fluid physiology and how this may be disrupted by pathological processes. The important themes in critical illness fluid research are discussed, with a particular focus on two emerging ideas: firstly, that individualising fluid treatment to the patient, their underlying disease state and the phase of that illness may be key to improving clinical outcomes using fluid interventions and, secondly, that fluids should be considered to be drugs, with specific indications and contraindications, dose ranges and potential toxicities.

Balanced versus unbalanced salt solutions: what difference does it make?

BACKGROUND

The infusion of crystalloid solutions is a fundamental part of the management of critically ill patients. These solutions are used to maintain the balance of water and essential electrolytes and replace losses when patients have limited gastrointestinal intake. They also act as carriers for intravenous infusion of medication and red cells. The most commonly used solution, 0.9% saline, has equal concentrations of Na(+) and Cl(-) even though the plasma concentration of Na(+) normally is 40 meq/L higher than that of Cl(-). The use of this fluid thus can produce a hyperchloremic acidosis in a dose-dependent manner, but it is not known whether this has clinical significance.

APPROACH

The first part of this article deals with the significance of Na(+) and Cl(-) in normal physiology. This begins with examination of their roles in the regulation of osmolality, acid-base balance, and generation of electrochemical gradients and why the concentration of Cl(-) normally is considerably lower than that of Na(+). The next part deals with how their concentrations are regulated by the gastrointestinal tract and kidney. Based on the physiology, it would seem that solutions in which the concentration of Na(+) is "balanced" by a substance other than Cl(-) would be advantageous. The final part examines the evidence to support that point.

CONCLUSIONS

There are strong observational data that support the notion that avoiding an elevated Cl(-) concentration or using fluids that reduce the rise in Cl(-) reduces renal dysfunction, infections, and possibly even mortality. However, observational studies only can indicate an association and cannot indicate causality. Unfortunately, randomized trials to date are far too limited to address this crucial issue. What is clear is that appropriate randomized trials will require very large populations. It also is not known whether the important variable is the concentration of Cl(-), the difference in concentrations of Na(+) and Cl(-), or the total body mass of Cl(-).

Relative survival benefit and morbidity with fluids in severe sepsis - a network meta-analysis of alternative therapies

BACKGROUND

Fluid resuscitation is widely practiced in intensive care units for the treatment of sepsis. A comparison of the evidence base of different fluids may inform therapeutic choice.

METHODS

The risks of mortality and morbidity (the need for renal replacement therapies (RRT)) were assessed in patients with severe sepsis. A network meta-analysis compared trials for crystalloids, albumin and hydroxyethyl starch (HES). A literature search of human randomized clinical trials was conducted in databases, the bibliographies of other recent relevant systematic reviews and data reported at recent conferences. Mortality outcomes and RRT data with the longest follow up period were compared. A Bayesian network meta-analysis assessed the risk of mortality and a pair-wise metaanalysis assessed RRT using crystalloids as the reference treatment.

RESULTS

13 studies were identified. A fixed-effects meta-analysis of mortality data in the trials demonstrated an odds-ratio (OR) of 0.90 between crystalloids and albumin, 1.25 between crystalloids and HES and 1.40 between albumin and HES. The probability that albumin is associated with the highest survival was 96.4% followed by crystalloid at 3.6%, with a negligible probability for HES. Sub-group analyses demonstrated the robustness of this result to variations in fluid composition, study source and origin of septic shock. A random-effects pairwise comparison for the risk of RRT provided an OR of 1.52 favoring crystalloid over HES.

CONCLUSION

Fluid therapy with albumin was associated with the highest survival benefit. The higher morbidity with HES may affect mortality and requires consideration by prescribers.

Dose and type of crystalloid fluid therapy in adult hospitalized patients

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Is sodium chloride worth its salt?

The choice of fluid for resuscitation of the brain-injured patient remains controversial, and the 'ideal' resuscitation fluid has yet to be identified. Large volumes of hypotonic solutions must be avoided because of the risk of cerebral swelling and intracranial hypertension. Traditionally, 0.9% sodium chloride has been used in patients at risk of intracranial hypertension, but there is increasing recognition that 0.9% saline is not without its problems. Roquilly and colleagues show a reduction in the development of hyperchloremic acidosis in brain-injured patients given 'balanced' solutions for maintenance and resuscitation compared with 0.9% sodium chloride. In this commentary, we explore the idea that we should move away from 0.9% sodium chloride in favor of a more 'physiological' solution.