Fluid Chloride and AKI in Cardiopulmonary Bypass

The Impact of Low Chloride Containing Fluids on Acute Kidney Injury After Cardiopulmonary Bypass as Assayed by Urinary [TIMP2*IGFBP7]


Lead Sponsor: University of New Mexico

Source University of New Mexico
Brief Summary

Acute kidney injury (AKI) is a potential complication of cardiac surgery. In animal models, excess exogenous Cl- ion in the bloodstream is associated with AKI. Normal saline IV fluid has higher levels of Cl- ion than the blood usually carries. An alternative IV fluid sold under the name Isolyte has lower Cl- ion levels. There is no literature comparing AKI outcomes in cardiac patients between patients receiving normal saline vs. Isolyte. The investigators propose to recruit and randomize 30 trial-completing cardiac surgery patients (up to 40 enrolled) into 2 study arms and compare renal outcomes.

Detailed Description

Acute kidney injury (AKI) is a potential complication for patients undergoing cardiac surgery. AKI in post-cardiac surgery patients is associated with adverse outcomes, such as prolonged intensive care and hospital stay, diminished quality of life, increased long-term mortality, and an increased risk of chronic kidney disease requiring dialysis. The mortality in cardiac surgery patients with AKI severe enough to require renal replacement therapy (RRT) can be as high as 60%. One of the putative agents associated with AKI in animal models receiving crystalloid fluids for resuscitative interventions is excess exogenous chloride ion (Cl-). As compared to non-Cl- containing solutions in animal models, excess Cl- appears to lead to a hyperchloremic metabolic acidosis, increased renal vascular resistance, reduced renal blood flow, and reduced glomerular filtration rate - all of which are injurious to kidney function.

Historically, one of the most common balanced salt-solutions used in adult cardiac surgery has been 0.9% normal saline (NS), a crystalloid solution with 154 mmol/L of Cl-. This is much higher than physiologic plasma levels of 103 mmol/L. Isolyte, a less commonly used crystalloid solution, is much closer to physiologic levels at 98 mmol/L Cl-. In the context of cardiac surgery, there is no literature expressly comparing the effects of balanced crystalloid solution such as Isolyte versus NS on AKI incidence. There is a single trial examining a low-Cl- containing colloid solution in cardiac surgery that found less metabolic acidosis; however, AKI or markers of AKI were not measured outcomes in that lone trial, so it is not known whether low Cl- solution will have any effect on AKI risk in humans.

AKI results from a series of extremely complex cellular and molecular pathways involving endothelial, epithelial, inflammatory, and interstitial cells. The gold standard for identification and classification of AKI is dependent on serial serum creatinine (Scr) measurements, but this measurement can be unreliable during acute changes in kidney function. Recent studies have shown that tissue inhibitor of metalloproteinase (TIMP-2) performs better than existing markers for predicting the development of moderate or severe AKI (Kidney Disease: Improving Global Outcomes [KDIGO] stage 2 or 3) within 12 hours of sample collection. To further enhance the sensitivity of utilizing TIMP-2, the investigators plan on also measuring urinary insulin-like growth factor-binding protein 7 (IGFBP7). Along with TIMP-2, IGFBP7 is also an inducer of G1 cell cycle arrest, a key mechanism implicated in AKI.

This study will utilize the urinary [TIMP-2]*[IGFBP7] multiplicative product as a composite biomarker index to investigate the impact of intraoperative infusion of NS versus Isolyte on post-cardiac surgery renal function. This biomarker should identify patients at risk of imminent (within 12 hours) AKI KDIGO criteria.

Patients presenting for cardiac surgery are already quite ill often with multiple comorbidities. Acute kidney injury in this population is associated with significant morbidity and mortality. The available literature indicates that a fairly simple intervention could plausibly reduce the incidence of AKI, but it has not yet been examined in humans. Generating an evidence basis for it will substantially improve the safety of patients who need cardiac surgery. This intervention to reduce AKI may also then be applied to the broader non-cardiac surgery population as well.

Overall Status Completed
Start Date January 2016
Completion Date February 2018
Primary Completion Date February 4, 2017
Phase Phase 2
Study Type Interventional
Primary Outcome
Measure Time Frame
Change in [TIMP2]*[IGFBP7] Biomarker Baseline and postoperatively at 24 hours
Secondary Outcome
Measure Time Frame
Serum Creatinine Level at 24 Hours 1 day
Serum Chloride Level at 24 Hours 1 day
Proportion of Patients With Need for Dialysis One week
Postoperative Arterial pH One day
Serum Creatinine Level at 48 Hours 2 days
Serum Chloride at 48 Hours 2 days
Enrollment 30

Intervention Type: Drug

Intervention Name: 0.9% Normal Saline (0.9% Sodium Chloride) injection

Arm Group Label: Normal Saline group

Intervention Type: Drug

Intervention Name: Isolyte S injection

Arm Group Label: Isolyte group



Inclusion Criteria:

- Planned on- or off-pump cardiac surgery including: bypass grafting, valvular procedures, congenital defect correction, and thoracic aortic procedures or a combination of these procedures

Exclusion Criteria:

- Emergency surgery

- Pregnancy

- Previous renal transplantation

- Documented moderate to severe acute kidney injury prior to enrollment (e.g. RIFLE-I or RIFLE-F/KDIGO stage 2 or 3)

- Patients already receiving dialysis (acute or chronic) or in imminent need of dialysis at time of enrollment

- Chronic kidney disease without baseline serum creatinine value obtained within 6 months of enrollment

Gender: All

Minimum Age: 18 Years

Maximum Age: N/A

Healthy Volunteers: No

Overall Official
Last Name Role Affiliation
Neal S Gerstein, MD Principal Investigator University of New Mexico
Facility: University of New Mexico Hospital
Location Countries

United States

Verification Date

April 2018

Responsible Party

Type: Principal Investigator

Investigator Affiliation: University of New Mexico

Investigator Full Name: Neal Gerstein

Investigator Title: Associate Professor

Has Expanded Access No
Condition Browse
Number Of Arms 2
Arm Group

Label: Normal Saline group

Type: Active Comparator

Description: 0.9% Normal Saline (0.9% Sodium Chloride) injection intravenously as needed. The amount administered (dosage, frequency, and duration) will be left to the clinical judgment of the attending physicians, and will follow usual patterns of use in cardiac surgery patients.

Label: Isolyte group

Type: Experimental

Description: Isolyte S (B Braun, Irvine CA) injection intravenously as needed. The amount administered (dosage, frequency, and duration) will be left to the clinical judgment of the attending physicians, and will follow usual patterns of use in cardiac surgery patients. Isolyte S is a prepackaged solution containing sodium chloride 0.53%, sodium gluconate 0.5%, sodium acetate trihydrate 0.37%, potassium chloride 0.037%, and magnesium chloride hexahydrate 0.03% w/v.

Patient Data Yes
Study Design Info

Allocation: Randomized

Intervention Model: Parallel Assignment

Primary Purpose: Prevention

Masking: None (Open Label)

Source: ClinicalTrials.gov