Influence of Perioperational Acid-Base Balance Disorders on Early Graft Function in Kidney Transplantation

Transplanted Kidney Increases Nitric Oxide Formation With Metabolic Acidosis Reduction

OBJECTIVES

As a vasodilator, nitric oxide is considered to play a significant role in the homeostatic regulation of renal hemodynamics. To test the hypothesis that a kidney graft is capable of producing nitric oxide immediately after renal transplant surgery, we examined the possibility that it positively affects local metabolic acidosis.

MATERIALS AND METHODS

In kidney transplant recipients, we analyzed renal vein and central vein blood samples, which reflect local and systemic metabolic alterations, respectively. Samples were taken immediately after kidney recirculation (that is, the first blood passing through after clamps are released) and at 5, 15, and 30 minutes thereafter. Levels of nitric oxide metabolites (nitrites, nitrates, and their sum), malondialdehyde (an indicator of oxidative damages), and parameters of acid-base balance (pH level, actual excess base, hemoglobin, actual bicarbonate, partial pressure of carbon dioxide, partial pressure of oxygen) were analyzed. Living kidney donors (the recipients' parents) were controls.

RESULTS

In renal vein samples, nitrates and the sum of nitrites and nitrates were significantly higher than that shown in control (P < .001) and central vein (P < .05) samples, suggesting an immediate increase in nitric oxide production in the transplanted organ. Metabolic acidosis occurred in both the renal and central vein, indicated by decreased pH and actual bicarbonate level as well as by negative actual base excess level. Only in the renal vein was an increased nitrite and nitrate associated with a reduction of negative actual excess base, thereby suggesting a decrease in anion formation.

CONCLUSIONS

Transplanted kidneys increase nitric oxide production immediately after organ transplant surgery, which positively affects local metabolic acidosis. The mechanism for this effect is likely local circulation improvement.

Acid-Base Balance Disorders During Kidney Preservation in Cold Ischemia

BACKGROUND

Acid-base balance disorders are a crucial element of ischemia-reperfusion injury during organ transplantation. Hypoxia during organ procurement and storage cause cellular homeostasis imbalance with impact on further graft function. Acidosis in preserved kidney caused by lactate accumulation may have an important role as a common denominator of various pathways leading to cellular damage.

METHODS

Our trial sought to answer questions regarding a range of pH alterations in the kidney before the transplantation, their potential cause, and how this may affect further outcome of the kidney transplantation procedure. Perfusion fluid for pH analysis was obtained from perfusion pump (PP) or through kidney flushing at the end of preservation depending on the storage method.

RESULTS

A total of 66 sample results were collated with the data from the transplant registry, hospitalization, and outpatient department. Statistical analysis was conducted linking pH results with factors related to donor, recipient, preservation, and outcome according to designed schematics. Mean perfusate pH was significantly lower in simple hypothermia (SH) vs the PP storage group (6.77 vs 7.11; P < .001). All samples of perfusate pH in the SH group were below physiological values (<7.35), and in 10% of samples in the SH group, pH >7.00.

CONCLUSIONS

We concluded that kidney storage in cold ischemia is associated with organ acidosis independent of preservation method and that SH is correlated with significantly bigger acidosis than storage in PP, which is an important procedure removing an excessive amount of hydrogen ions from kidney microcirculation, decreasing cell damage.