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Using a crystalloid solution during surgery was better than saline for improving deceased donor kidney transplant outcomes, according to the BEST-Fluids trial.

Compared with standard saline IV fluids, deceased donor kidney transplant recipients who instead received a balanced low-chloride crystalloid solution had a 25% lower relative risk for experiencing delayed graft function (adjusted RR 0.74, 95% CI 0.66-0.84, P<0.0001), reported Michael Collins, MBChB, PhD, of Royal Adelaide Hospital in Australia.

Delayed graft function, defined as needing dialysis within 7 days of the kidney transplant, occurred in 30% of the balanced crystalloid group versus 39.7% of the saline group, Collins said during a presentation at the American Society of Nephrology Kidney Week.

More patients in the saline group needed dialysis due to uremia or volume control, while the rate of hyperkalemia was similar between the two groups.

"In this trial, to prevent one case of delayed graft function, the number needed to treat was 10," Collins pointed out.

The findings suggest, he said, that the standard-of-care IV fluid in deceased donor kidney transplantation should be balanced crystalloids instead of saline. In this trial, the Plasma-Lyte 148 solution was used.

"They are cheap, readily available, and this simple change in kidney transplant practice can easily be implemented globally now," he said.

Collins emphasized that IV fluids obviously play an important role during kidney transplantation in order to maintain volume status and blood pressure. High volumes are often used too, running as much as 5 to 9 mL from the time of surgery to the second postoperative day.

Although saline (0.9% sodium chloride) is currently the standard of care, there have been "concerns" over its use due to the supra-physiological chloride content that could result in hyperchloremic acidosis, especially with high-volume infusions. He pointed out prior research that linked hyperchloremia to kidney vasoconstriction and reduction in renal cortical perfusion, leading to reductions in glomerular filtration rate and urine volume.

Falling in line with their hypothesis, Collins noted that serum chloride and sodium levels were much higher in the saline group during the first 48 hours after transplant, while bicarbonate and pH levels were much lower for this group. There weren't any between-group differences for potassium, though.

There was also a higher urine output in the balanced crystalloid group, as well. Over the course of the first week post-transplant, there weren't any serum creatinine differences between the groups.

In one of the trial's secondary outcomes, the saline group required 190 more dialysis treatments during the 28 days after transplant (596 vs 406). Up until week 12 after transplantation, those on the balanced crystalloid group also saw a shorter time to dialysis independence.

There weren't any significant differences seen when it came to several other secondary outcomes, as follows (although Collins noted that the trial might not have been powered enough to pick up on any):

• Number of transplant biopsies by day 28

• Acute rejection episodes by week 52

• Graft failure by week 52

• Graft function by week 52

• Time to hospital discharge

• Mortality by week 52

Besides a higher number of saline patients being admitted to the ICU requiring ventilation (3% vs <1%), adverse events were similar between the groups.

In a pre-specified subgroup analysis, several of the patient subgroups significantly favored balanced crystalloid solution over saline, one of which included ischemic time broken down by two different time points (less than 10 hours versus 10+ hrs; and less than 14 hrs vs 14+ hrs). But when it came to donor type, balanced crystalloids was only favored by kidneys donated after circulatory death, not after brain death. It was also only favored when no machine perfusion was used and for those in the second and third tertiles of Kidney Donor Risk Index.

The trial included 404 children and adults (average age 55) receiving a deceased donor kidney transplant in each study arm. All patients had to weigh over 20 kg (about 44 lbs) at the time of recruitment and could not be receiving multi-organ transplantation. The two most common causes of kidney failure were glomerulonephritis and diabetic nephropathy.

More than half of the patients were white and 37% were female. The average body mass index was 27.

Clinicians determined the rate and volume of fluids administered. The trial fluids were used for all fluid needs from the time of randomization up through 48 hours after transplantation. Patients in the balanced crystalloid group received an average of 8 liters of fluids versus 7 liters for the saline group.

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