Prospective Assessment of Clinically Relevant Fluid Balance Thresholds Associated With Postoperative Complications in Advanced Ovarian Cancer

Abstract

Background: Reliable data on optimal fluid management in the perioperative period for patients with advanced ovarian cancer undergoing cytoreductive surgery is limited. These patients often present with malignant ascites and are prone to significant fluid shifts perioperatively. For this reason, our objective was to define clinical targets for optimal fluid balance and determine whether initial ascites should be included in fluid-loss calculations by examining the association between perioperative fluid balance and major postoperative complications.

Methods: This prospective, observational study conducted in a centralized and public healthcare system setting in Sweden between 2020 and 2023 included patients with advanced ovarian cancer, > 18 years of age, scheduled for upfront cytoreductive surgery, an ASA physical status I-III with no speech/language issues. The primary outcome was major postoperative complication within 30 days of surgery. The measurements of fluid input and output, cut-offs for fluid balance, perioperative time, and postoperative complications were defined a priori. The association between fluid balance and major postoperative complications was assessed by multivariable regression, adjusted for predefined covariates, yielding odds ratios (OR) with 95% confidence intervals (CI).

Results: Of 175 enrolled patients, 162 were included in the final analysis. In the adjusted analysis, there was a significant association between fluid balance of 1750-2700 mL, OR 3.40 (95% CI 1.06-10.9; p = 0.04) and > 2700 mL, OR 3.91 (95% CI 1.33-11.5; p = 0.01) and major postoperative complications. When including initial ascites as fluid loss, a balance of > 2700 mL was associated with major postoperative complications, OR 2.59 (95% CI 1.01-6.66, p = 0.047).

Conclusion: An optimal target for perioperative fluid balance to decrease the odds of major postoperative complications is suggested to be < 1750 mL. If initial ascites is included as loss in the calculation of balance, the optimal target of fluid balance is suggested to be < 2700 mL. These results provide practical clinical reference values that may assist anesthesiologists and surgical teams in optimizing perioperative fluid management in advanced ovarian cancer.

Editorial comment: This secondary analysis of a trial ovarian cancer operative cohort assessed the relation of the estimated fluid balance over the operative day 24 h to major postoperative complications. The findings showed that the groups where the fluid balance was in the categories higher and also most positive had higher odds for having a major complication compared to the group with lowest fluid balance. Ascities fluid was an issue in this cohort, which was managed in the analysis.

Trial registration: ClinicalTrials.gov: NCT04065009.

FIGURE 1

Selection of women for analysis from the intra peritoneal local anesthetics in advanced ovarian cancer (IPLA OVCA) trial. The perioperative and clinical characteristics of the 13 patients excluded due to missing data on fluid balance are presented in Table S4.

FIGURE 2

Forest plot of uni‐ and multivariable logistic regression of odds of major postoperative complications¹ in patients with ovarian cancer, including fluid balance. ASA, American society of anesthesiologists; CI, confidence interval; FIGO, International federation of gynecology and obstetrics; OR, odds ratio. ¹Defined as Clavien‐Dindo grade ≥ 3 within 30 days after surgery. ²Number of patients with major postoperative complications, defined as Clavien‐Dindo grade ≥ 3 within 30 days after surgery. ³Adjusted for: Age, suspected FIGO stage (IV, III), ASA score (I, II, III), preoperative plasma Albumin, surgical complexity score according to Mayo (low, medium, high). ⁴Walds test. #Total fluid given from start of surgery until 06:00 the day after surgery minus total fluid losses from start of surgery until 06:00 am the day after surgery. ##Initial ascites at start of surgery included in total fluid losses.