Intraoperative isotonic balanced versus hypotonic crystalloids on postoperative sodium homeostasis in small children undergoing major neurosurgery: a randomized controlled trial.

Background: Whether intraoperative isotonic balanced maintenance fluid is associated with less variation in sodium homeostasis in small children undergoing major neurosurgery remains unknown.

Methods: Patients aged up to 6 years undergoing major neurosurgery were randomly assigned to receive either isotonic balanced solution (IB) or 0.2% hypotonic solution (H) as intraoperative maintenance fluid. Serum electrolyte levels were measured from preoperative baseline to 6 d following surgery.

Results: Eighty patients were included in the primary analysis. Serum sodium change was significantly less in the IB patients from the end of surgery continuing to 24 h following surgery (at the end of surgery: -1.4 ± 3.6 versus - 4.6 ± 3.5 mmol/l, P < 0.001; 24 h post: -1.2 ± 4.8 versus - 3.4 ± 2.5 mmol/l, P = 0.028). Twenty (50%) of the IB patients and 25 (63%) of the H patients had serum sodium change > 2.5 mmol/l 24 h following surgery (6.0 ± 3.4 versus 4.8 ± 2.1 mmol/l), with 13 (33%) of the IB patients and 25 (63%) of the H patients having sodium decrease > 2.5 mmol/l (6.4 ± 3.7 versus 4.8 ± 2.1 mmol/l) (P = 0.007). Seven patients in group IB experienced an increase in blood sodium levels exceeding 2.5 mmol/l (median, 4.1 [range 2.7 ∼ 9.2] mmol/l). Notably, 10 (25%) of the IB patients and 6 (15%) of the H patients had sodium variation > 5 mmol/l (median, 8.5 [range 5.1 ∼ 14.6] versus 7.2 [range 5.5 ∼ 11.1] mmol/l). Immediately following surgery till 24 h postoperatively, hyponatremia was less observed in the IB patients compared with that in the H patients. The IB patients had higher hemoglobin levels and less diuresis 48 h postoperatively. No symptoms including altered mental status, seizure, and circulatory overload were observed in all patients.

Conclusion: Intraoperative isotonic balanced solution infusion resulted in statistically but not clinically minimal variation of sodium homeostasis and hemoglobin level postoperatively in small children undergoing major neurosurgery, compared to the use hypotonic solution. Potentially excessive sodium fluctuation following isotonic balanced maintenance fluid infusion should be cautioned, even for a brief period of infusion.

Trial registration: Chinese Clinical Trial Registry ( http://www.chictr.org.cn/ ).

Registration number: ChiCTR2100046539. Registration date: May 21, 2021. Principal investigator: Lin-Lin Song.