Sodium homeostasis during liver transplantation and correlation with outcomes.

BACKGROUND: Reports of perioperative serum sodium increase in liver transplant (LT) recipients are mostly restricted to unintentional rapid serum sodium overcorrection with subsequent development of central pontine myelinolysis. We examined intraoperative serum sodium changes and their effect on short-term outcomes after LT.
METHODS: We retrospectively analyzed data of all LT recipients over a period of 3.5 years. Collected information included preoperative and postoperative serum sodium (Napre and Napost), delta sodium (ΔNa), intraoperative serum sodium peak and trough with corresponding maximum ΔNa, intraoperative peak blood glucose, history of hepatic encephalopathy, perioperative diuretics, intraoperative administration of vasopressin, dopaminergic agents, alkalizing drugs (sodium bicarbonate [NaHCO3], tromethamine), crystalloids, colloids, fresh frozen plasma (FFP), and packed red blood cells (PRBC). The delta of serum osmolality (ΔOsm) was calculated from Napre and Napost, blood urea nitrogen, and blood glucose values, and the correlation between ΔNa and ΔOsm was examined. Outcomes analyzed included intubation for ≥2 days, postanesthesia care unit/surgical intensive care unit (PACU/SICU) length of stay (LOS) for ≥2 days, need of SICU admission, hospital LOS, postoperative neurological complications, and mortality. Univariate and multivariate analyses were performed to test associations between ΔNa and outcomes. A P value <0.005 was considered significant.
RESULTS: Data of 164 patients were analyzed. Their ΔNa was 5.3 ± 4.5 (mean ± SD) mEq/L. A lower Napre was associated with greater ΔNa, a relationship likely due to the regression to the mean. In a subgroup of patients with Napre < 130 mEq/L, ΔNa was 11.0 ± 3.6 mEq/L, significantly higher than in normonatremic patients (P < 0.0001). Mortality and neurologic complications were not affected by changes in ΔNa (all P ≥ 0.41). An increase in ΔNa was associated with higher odds of prolonged intubation and prolonged PACU/SICU LOS in univariate and multivariate regression analyses (P = 0.0003 and P = 0.0049, respectively, for adjusted odds ratios). The odds ratios for associations of ΔNa with those outcomes did not differ between patients treated versus not treated with NaHCO3. The intraoperative ΔNa was significantly higher in patients with intraoperative hyperglycemia (P < 0.0001). Intraoperative administration of NaHCO3 and the number of transfused FFP and PRBC units were also associated with a significantly higher ΔNa (P = 0.0001). The ΔNa correlated significantly with ΔOsm.
CONCLUSIONS: A larger intraoperative increase in ΔNa is associated with worse recipient short-term outcomes. Patients with preoperative hyponatremia may be at particular risk. ΔNa increases with the intraoperative use of NaHCO3, quantity of FFP, and PRBCs transfused, as well as with intraoperative hyperglycemia. Potential differences on sodium homeostasis between NaHCO3 and tromethamine use for intraoperative pH adjustment should be prospectively investigated.