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

Background 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. Methods 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. Results 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. Conclusion 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.