Analysing association between fluid balance and extubation success

Abstract

Introduction: Water constitutes approximately 45–75% of total body weight and is essential for physiological functions including metabolism, temperature regulation, and tissue maintenance. In critically ill, mechanically ventilated patients, fluid homeostasis is disrupted due to reliance on intravenous fluids and impaired physiological responses. Improper fluid management may lead to pulmonary complications such as edema, which can negatively impact extubation outcomes and overall prognosis. Evidence increasingly suggests that maintaining an optimal fluid balance may improve extubation success and reduce morbidity. Objectives: Primary Objective: To examine the relationship between fluid balance from the day of intubation and extubation outcomes in patients mechanically ventilated for more than 24 hours who underwent successful spontaneous breathing trials (SBTs). Secondary Objective: To derive an optimal input/output (I/O) ratio to guide fluid administration in critically ill patients. Materials and Method: A prospective observational study was conducted over 12 months at BLDE, Shri B.M Patil Medical College Hospital and Research Centre, Vijayapura. The study included adult patients admitted to the ICCU and CCU who were intubated for medical reasons and mechanically ventilated for over 24 hours. Patients who completed an SBT using a T-piece or CPAP mode and underwent their first (index) extubation were included. Patients intubated before admission, post-operative or trauma cases, those extubated within 24 hours, or who underwent tracheostomy were excluded. Data were analyzed using JMP Pro 16 and SPSS v20. Statistical tests included the independent t vii Docusign Envelope ID: EFEB1A7B-4878-456C-83FB-4F7C23FAF536 test, Mann-Whitney U test, chi-square test, and ROC curve analysis. A p-value <0.05 was considered statistically significant. Results: Among categorical variables such as gender, primary diagnosis, type of SBT, diuretic use, and dialysis, no significant associations were found with extubation outcomes. However, cumulative fluid balance showed a statistically significant difference between extubation success and failure groups. Other continuous variables like age, individual fluid input/output volumes, and duration of mechanical ventilation did not predict extubation outcomes. ROC analysis for the I/O ratio yielded an AUC of 0.558 with a non-significant p value (0.140), indicating only marginal discriminative ability. A cut-off ratio of 1.129 offered moderate sensitivity and specificity but lacked predictive reliability as a standalone marker. Conclusion: Cumulative fluid balance emerged as a potential key factor in predicting extubation outcomes, whereas the fluid input/output ratio alone did not serve as a reliable predictor. These findings underscore the complexity of fluid management in critically ill patients and support the integration of fluid balance metrics into broader, multivariate predictive models. Future studies should focus on refining these models to improve extubation success rates and patient outcomes.