Perioperative plasma sodium level course in neonatal critical congenital heart disease surgery and new postoperative white matter injury

Abstract Background Surgical advances have increased life expectancy in critical congenital heart disease (CCHD), yet long-term complications remain prevalent. Perioperative dysnatremia contributes to adverse clinical and possibly also neurologic outcomes in neonatal CCHD. This study aims to describe perioperative plasma sodium levels in neonatal CCHD and investigate the potential influence of a rapid increase on new postoperative white matter injury (WMI). Methods We included 158 neonates with CCHD who underwent cardiac surgery with cardiopulmonary bypass (CPB) at ≤ 6 weeks old. Plasma sodium levels were retrieved perioperatively. Pre- and postoperative brain magnetic resonance imaging could be obtained for 115 neonates. Results Perioperative dysnatremia, either hyponatremia (< 135 mmol/L ) or hypernatremia (> 145 mmol/L) , was present in 88.6% of neonates. Perioperative sodium levels were affected by time of measurement after the start of surgery ( β = 0.25 (0.22, 0.28)), preoperative diuretics ( β = -2.15 (-3.19, -1.11)), sodium content of the CPB priming solution ( β = 0.16 (0.03, 0.30)), and postnatal age at surgery ( β = -0.11 (-0.18, -0.04)) in a mixed effect model. This model revealed a rapid average intraoperative sodium level increase of 0.25 mmol/L per hour of surgery. No associations were found between intraoperative sodium change and new WMI ( β = -0.10 (-0.23, 0.02)). Conclusions In this study we report a high prevalence of perioperative dysnatremia and a rapid plasma sodium increase after initiation of CPB in neonates with CCHD. We were unable to confirm an association between rapid sodium increase and adverse clinical outcome or the presence of new postoperative WMI.