Critical Care Alert: Effects of Buffered Crystalloids vs. Saline on Acute Kidney Injury in Resuscitation of ICU Patients

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A 60-year-old man presents to the emergency department with fever, productive cough, and lethargy. He is diagnosed with severe sepsis secondary to pneumonia and he requires admission to the intensive care unit (ICU). He has an elevated creatinine compared to his baseline and he is hypotensive on arrival. You verbally order wide open intravenous (IV) fluids while evaluating the patient, and your nurse asks, “What type of fluids would you like me to hang?”

Article

Effects of Buffered Crystalloids vs. Saline on Acute Kidney Injury in Resuscitation of Intensive Care Unit Patients. Young P, Bailey M, Beasley R, et al. Effect of a Buffered Crystalloid Solution vs Saline on Acute Kidney Injury Among Patients in the Intensive Care Unit. JAMA. 2015;314(16):1701.

Objective

Evaluating the rates of acute kidney injury (AKI) in ICU patients who receive normal saline compared to Plasma-Lyte 148 during their resuscitation.

Background

Giving IV fluids is one of the most common interventions performed in the hospital, especially in the ICU and emergency department (ED). 0.9% sodium chloride (saline) is the most commonly used fluid but there are rising concerns over its safety, particularly regarding the high chloride content and its contribution toward the development of AKI and acidosis. Retrospective and observation data suggests that buffered crystalloids such as Lactated Ringer’s or Plasma-Lyte may be associated with less risk of AKI, but no prospective trials have been conducted. This study aimed to compare the rates of AKI when saline or Plasma-Lyte are used in the resuscitation of ICU patients.

Design

  • Cluster randomized, double-crossover study involving four tertiary ICUs in New Zealand, three of which were medical and surgical and one of which predominantly treated cardiothoracic and vascular surgical patients.
  • Enrolled patients over 28-week period with four 7-week blocks.
  • Two ICUs used fluid A for 7 weeks while the other two ICUs used fluid B for 7 weeks and then switched. Two crossovers occurred so each ICU used each fluid twice.
  • Physicians were allowed to use other fluid types or to give open-label saline or Plasma-Lyte as they deemed clinically necessary.
 Saline (mEa/L)Plasma-Lyte (mEq/L)
Sodium154140
Chloride15498
Acetate27
Gluconate23
Potassium5
Magnesium3
  • Enrollment determined by time period and no sample size calculations were performed.
  • Analysis performed on an intention-to-treat basis with missing data filled in with scenarios in which every patient had AKI or no patients had AKI.

Inclusion criteria: All patients receiving crystalloid therapy in the ICU

Exclusion criteria: Patients with end-stage renal disease already on renal replacement therapy (RRT) and patients admitted to the ICU for palliative care or organ donation

Primary outcome: Proportion of patients with AKI based on serum creatinine measurements using the risk, injury, failure, loss, and end-stage renal failure (RIFLE) definitions. Anything at a level of injury, which is defined as a doubling of serum creatinine, or greater was counted as AKI.

Secondary outcomes: Change in creatinine from baseline to peak, cumulative incidence of AKI, RRT use during hospital stay and after discharge, indications for RRT in the ICU, rates and duration of mechanical ventilation, proportion of patients readmitted to the ICU during the same hospital stay, and ICU and in-hospital mortality.

Key Results

  • 1162 patients received buffered crystalloid and 1116 patients received saline.
  • Majority of patients admitted to ICU after elective surgery, with 13.9% of patients being admitted from the ED.
  • Patients received 2 liters of IV fluid, on average.
  • Rate of AKI:
    • Plasma-Lyte: 9.6%
    • Saline: 9.2%
  • Rate of RRT during hospitalization:
    • Plasma-Lyte: 3.3%
    • Saline: 3.4%
  • Rate of in-hospital mortality:
    • Plasma-Lyte: 7.6%
    • Saline: 8.6%
  • None of these differences were statistically significant and no patients required RRT after hospital discharge.
  • One reported serious adverse event was felt to be attributed to the study treatment, with a patient admitted to the ICU following a renal transplant and assigned to the Plasma-Lyte group; the patient subsequently developed lactic acidosis with multiorgan failure and death without another obvious cause.

Authors’ Conclusion and Limitations

  • Use of Plasma-Lyte as a buffered crystalloid for fluid resuscitation in the ICU did not reduce the risk of AKI compared to saline.
  • Further large randomized clinical trials are needed to look at higher-risk populations and directly measure mortality.
  • Study limited by lack of sample size calculations, exposure to IV fluids before enrollment, low overall rate of AKI, low volumes of IV fluid resuscitation.

Our Conclusions and Applications for the Emergency Department

  • No current evidence to support one type of fluid over the other during resuscitation.
  • May be reasonable to choose buffered crystalloid in significantly hyperchloremic patients.
  • Patients in this study were mostly post-operative patients and do not accurately represent the average critically ill patient requiring resuscitation in the ED.
  • A study that looks at ED patients or has a much higher percentage of emergency resuscitations would be necessary to determine if one type of fluid is better than another in our clinical setting.
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