Post-operative Fluid Restriction to Prevent Delayed Hyponatremia after Endoscopic Transsphenoidal Surgery.

Abstract

Background: Readmission following endoscopic endonasal transsphenoidal surgery (EETS) for pituitary neuroendocrine tumor (PitNET) and other sellar pathology is most commonly due to delayed hyponatremia. Studies suggest post-operative fluid restriction (FR) reduces delayed hyponatremia. We present a prospective randomized controlled study evaluating post-EETS FR.

Methods: 300 participants were scheduled for EETS (2016-2023) at a single institution. Patients with CKD, CHF, arginine vasopressin deficiency on post-operative day (POD) 3, chronic hyponatremia, and untreated adrenal insufficiency or hypothyroidism were excluded. Groups included control (ad-lib, n=94), moderate FR (1.8 L/day or 2 L/day weight >100 kg, n=39), and strict FR (1 L/day or 1.2 L/day weight >100 kg, n=62) from POD 3-14. Incidence of overall, moderate, and severe hyponatremia (Na <135, 125-129, and <125 mEq/L), readmission rates, fluid intake, and thirst were evaluated.

Results: The incidence of overall hyponatremia was 31.9%, 28.2%, and 21.0% in control, moderate FR, and strict FR groups, and the incidence of severe hyponatremia was 7.4%, 5.1%, and 0% in control, moderate FR, and strict FR groups. Nadir Na level was higher (1.81 mEq/L; 95% CI, 0.34 to 3.27; P=0.02) and severe hyponatremia occurred less frequently (95% CI, 0.00 to 1.02; P=0.04) in the strict FR vs. control group. Readmission was lower in the strict FR (1.6%, n=1) vs. control group (6.4%, n=6).

Conclusion: Post-operative FR decreases rates of delayed hyponatremia and related readmission compared to patients drinking ad-lib. Further studies are needed to assess the optimal volume and duration of FR after EETS.