Postoperative fluid restriction to prevent hyponatremia after transsphenoidal pituitary surgery: An updated meta-analysis and critique

Hyponatremia is a common and potentially dangerous complication of transsphenoidal surgery. Prophylactic postoperative fluid restriction has been trialled as a method to reduce the incidence of postoperative hyponatremia.A systematic review of the literature was performed in accordance with the PRISMA statement. Risk of bias was assessed using the MINORS criteria. Meta-analysis was performed using the random-effects model.A total of 6 retrospective cohort studies were available for analysis. Fluid restriction was commonly between 1000 and 1500 ml/day and limited to the first postoperative week. Overall, the rate postoperative hyponatremia was fourfold less in the fluid restricted cohorts (3.4 % vs 11.2 %, OR 0.24 (95 %CI 0.15-0.38), p 0.01). There was no difference in readmission rates (1.4 % vs 3.9 %, OR 0.32 (95 %CI 0.09-1.13), p = 0.08) or postoperative diabetes insipidus (14.5 % vs 18.6 %, OR 0.82 (95 %CI 0.50-1.36), p = 0.45) between fluid restricted and control cohorts.Prophylactic postoperative fluid restriction is a cheap, easily implemented intervention that appears to reduce the rate of postoperative hyponatremia, but not necessarily re-admission rates. Whether these prevented cases of hyponatremia are clinically significant remains to be demonstrated.