Postoperative pulmonary complications (PPCs) are a significant concern following thoracic surgeries, affecting 12%–40% of patients and contributing to a mortality rate exceeding 50%. Strategies to minimize PPCs are crucial, with intraoperative fluid management being a key focus. While excessive fluid administration has been linked to increased pulmonary complications, there is no consensus on the optimal fluid strategy. This systematic review and meta-analysis aimed to evaluate the impact of intraoperative fluid volume on PPCs and determine whether a restrictive or liberal fluid strategy is preferable.
Methodology
The study followed PRISMA guidelines and included data from PubMed and EMBASE databases up to August 31, 2024. A total of 759 articles were screened, with 24 selected for full-text review, ultimately yielding 11 eligible studies for quantitative synthesis. The studies compared the amount of intraoperative intravenous fluid (IVF) administered between patients who developed PPCs and those who did not. Additionally, the risk ratio of PPCs in restricted versus liberal fluid strategies was analyzed.
Key Findings
- Fluid Volume and PPCs: Patients who developed PPCs received significantly higher intraoperative fluid volumes compared to those who did not. The pooled mean difference in IVF was 1.51 ml/kg/h (P = 0.001). This suggests a direct association between increased intraoperative fluids and higher PPC risk.
- Restricted vs. Liberal Fluid Strategies: A pooled analysis showed that PPC incidence was higher in patients who received liberal fluid administration compared to those with restricted fluid intake. The risk ratio (RR) for PPCs in the liberal fluid group was 0.58 (95% confidence interval: 0.33–1.02, P = 0.06). While not statistically significant, the trend suggests a potential benefit of restrictive fluid management.
- Heterogeneity and Bias: The included studies exhibited high methodological and statistical heterogeneity, which may impact the strength of the conclusions. Most studies were observational, introducing inherent biases, such as variations in patient characteristics, surgical techniques, and fluid administration protocols.
Discussion
The findings support the hypothesis that excessive intraoperative fluid administration may contribute to pulmonary complications post-thoracic surgery. Overhydration increases hydrostatic pressure in pulmonary capillaries, potentially leading to pulmonary edema, acute lung injury (ALI), pneumonia, and respiratory distress. However, restricting fluids too aggressively may also pose risks, such as reduced organ perfusion and increased complications related to hypovolemia.
Several factors influence PPC risk beyond fluid management, including patient comorbidities, smoking history, surgical approach (open vs. video-assisted thoracic surgery), and preoperative treatments such as chemotherapy or radiotherapy. For example, one study found that neoadjuvant therapy increased PPC risk, and another highlighted that surgeries for lung malignancy had higher complication rates than those for benign conditions.
A critical limitation of the review is the lack of randomized controlled trials (RCTs), which would provide stronger evidence for fluid management strategies. The studies included varied in their definitions of restrictive and liberal fluid strategies, making direct comparisons difficult. Some defined restrictive strategies as <6 ml/kg/h, while others used a threshold of <16.8 ml/kg/h. Future research should standardize these definitions and investigate individualized fluid management approaches.
Conclusion and Future Directions
The evidence suggests that limiting intraoperative fluid administration may reduce PPC risk in thoracic surgery patients. However, the high heterogeneity among studies and the observational nature of the data highlight the need for well-designed RCTs to confirm these findings. Until more definitive guidelines emerge, a cautious approach—balancing fluid restriction with adequate tissue perfusion—should be considered in clinical practice.
Study Ranking = 3 (Moderate Quality) This meta-analysis provides valuable insights but is limited by its reliance on observational studies with high heterogeneity and potential biases. While the findings suggest a link between fluid volume and PPCs, the absence of well-controlled randomized trials reduces the strength of the conclusions. Further RCTs are needed to establish definitive clinical recommendations.
