This study investigated the effect of the type and volume of perioperative IVFs on the risk of kidney graft dysfunction and post-transplant electrolyte disturbances in children who had received KT.
A common IVF used during KT is NS, which is often preferred for its cost-effectiveness and availability, although BC and colloid solutions may also be used. NS (0.9% saline) has equal sodium and chloride (154 mmol/L each) and higher osmolality (308 mOsm/kg) than extracellular fluids [5] and it is potassium-free crystalloid. Thus, because it is potassium-free, its use may prevent hyperkalemia, a serious KT complication [4]. However, NS may worsen biochemical outcomes. High chloride NS can cause acidosis and hyperkalemia [7]. Furthermore, some studies suggest that NS may have a detrimental effect on kidney function, especially in patients who are at risk for kidney impairment [9, 10]. BC solutions like RL or Plasma-Lyte have less sodium and chloride than NS. In addition, they contain potassium, magnesium, calcium and buffer anions either lactate or acetate. A Cochrane review and meta-analysis of six trials involving 477 kidney recipients found that BC solutions reduced the likelihood of hyperchloraemic metabolic acidosis more than saline, but the effects on DGF and hyperkalaemia risks were unclear [11]. Colloids, which are less common than crystalloids, have large molecules like albumin or starch that boost intravascular volume, but they cost more and may cause more adverse events [12].
According to our study, there was no significant difference between the group of patients who received NS with a volume of more than 70% (HNS group) of their total perioperative IVFs and those who received NS with a volume of 70% or less (LNS group) of their total perioperative IVFs in terms of SGF, CRR1, CRR2, serum potassium, serum bicarbonate, or metabolic acidosis in the IPT period or on PTD 1. However, the HNS group had higher serum sodium and chloride levels on PTD 1, and a higher incidence of hypokalemia. Previous studies [7, 13] agree with this finding, but also show that Plasma-lyte or RL improve pH and chloride levels compared with NS.
SGF has similar graft loss risk as DGF and can leads to longer hospital stay, more rejection, and worse graft survival [14–17]. We found that the median CRR2 and CRR1 were similar between HNS and LNS groups and that SGF at PTD 2 and PTD 1 have no significant difference between HNS and LNS groups. Similarly, Li et al. [18] and Alkouny et al. [19] found no difference in graft function between NS and BC solutions. Furthermore, a Cochrane review in 2016 concluded that there is no clear evidence that BC solutions lead to improved graft outcomes compared to NS [20].
In contrary to our findings, a large cohort study of 2,515 kidney transplant recipients found that those who received a high percentage of NS (> 80%) were more likely to experience DGF than those who received a low percentage of NS [10]. In this later study, the adjusted odds ratio for DGF was 1.55 (1.09 to 2.19) for the high NS group compared with the low NS group.
We also found that the electrolyte imbalances were similar between the two groups, except for lower hypokalemia in LNS (21.4%) than HNS (33.3%; p = 0.029). Both groups also had similar levels of serum creatinine, sodium, potassium, chloride, and bicarbonate at IPT, but HNS had higher sodium (p = 0.043) and chloride (p = 0.034) at PTD1 than LNS. Williamson et al. [21] found that NS is associated with a higher risk of electrolyte disturbances, including hyperkalemia, but a lower risk of hyponatremia.
The higher serum sodium and chloride levels in the HNS group on PTD 1 is likely due to the higher concentration of sodium and chloride in 0.9% saline. This could cause transient hyperchloremia, which was corrected by the kidney over time. The higher incidence of hypokalemia in the HNS group may be related to absence pf potassium in NS or to other factors, such as diuretic use or acid-base status.
The results of our study suggest that there is no need to restrict the use of NS in pediatric patients who received KT, and that the standard practice for perioperative IVFs administration in pediatric KT is adequate. However, larger randomized studies are needed to confirm these findings. The detailed reporting of perioperative variables and outcomes is the strength of our study. However, our study has several limitations that should be considered when interpreting our results. First, this study was retrospective which may introduce selection bias or missing data that could affect the results and limits our ability to establish causality and control for confounding factors. Second, our study was conducted at a single center with a relatively small sample size, which limits the limit the statistical power, the external validity and generalizability of our results to other settings and populations. Third, our study did not account for other factors that may affect SGF or electrolyte balance, such as donor characteristics, cold ischemia time, surgical technique, and postoperative complications.
We suggest that future studies should use a prospective randomized controlled design to confirm the findings of this study and to explore other factors that may affect the graft function or electrolyte balance in pediatric KT recipients. Future studies should also include a larger and more diverse sample of patients and donors from different centers and regions, to increase the generalizability and applicability of the results.