Fluid Strategies During the Peri-Operative Period

Surgery is a major stressor on the body, and while the goal is for it to be lifesaving or quality of life-preserving, most procedures are associated with some level of postoperative complications. One variable that affects surgical outcomes is fluid management during the procedure, due to its role in supplying oxygen to meet bodily demands and maintaining electrolytes and volume status¹. While avoiding too much fluid peri-operatively is a generally agreed-upon principle, the nuance of fluid management strategies beyond that is still being studied³.

Fluid management strategies are classified as restrictive (less than 1.75 L per day), balanced (1.75-2.75L per day) or liberal (above 2.75L)¹. Currently the Enhanced Recovery After Surgery (ERAS) guidelines recommend restrictive fluid management, specifically trying to achieve “zero-balance” to reduce risk of fluid overload¹. Earlier research showed better outcomes with the zero-balance strategy, with lower postoperative morbidity and mortality¹. However, recently the largest study comparing zero-balance to a moderately liberal fluid management strategy showed that the zero-balance strategy was in fact associated with a higher incidence of postoperative acute kidney injury³. Because this more recent study was the largest randomized control trial on this subject, these results call the ERAS guidelines into question³.

Since fluid management is so critical to postoperative outcomes, it is important to elucidate which strategy works best, which was the goal of a meta-analysis conducted on randomized control trials in major abdominal elective surgery published in Critical Care³. This systematic review found no overall differences in major postoperative complications and mortality between restrictive and liberal fluid management strategies³. When specifically looking at renal complications, the liberal strategy did in fact seem to result in a lesser incidence of acute kidney injury³. Acute kidney injury did not seem to cause increased morbidity and mortality in these patients, however, it can in patients undergoing cardiothoracic surgery, so this data is still clinically relevant³. In fact, in patients undergoing cardiothoracic surgery, the restrictive strategy has been linked to more composite complications than less restrictive strategies². A 2020 study on patients undergoing open thoracotomies found that 4-5 mL per kg was the optimal infusion rate of fluid, not the less than 2 mL per kg that was previously recommended². The smaller amount of fluid was associated with increased development of acute respiratory distress syndrome postoperatively².

The evidence is mixed for whether aggressive, restrictive fluid management is truly the best strategy during surgery. On one hand, convention and ERAS guidelines say that it is associated with lower complication rates and better outcomes¹. However newer studies have not supported those recommendations, showing that there is no difference between restrictive and liberal fluid strategies, and that, when looking at specific complications, liberal strategies may, in fact, be better³. This is an important question to be solved in research surrounding peri-operative protocols, as it has the potential to save more lives and improve quality of life.

References

1. Gustafsson UO, Scott MJ, Schwenk W, Demartines N, Roulin D, Francis N, et al. Guidelines for perioperative care in elective colonic surgery: Enhanced recovery after surgery: ERAS society recommendations. World Journal of Surgery, 2013; 37:259–284.
2. Kim JA, Hyun JA, Oh RA, Choi J. Restrictive intraoperative fluid management was associated with higher incidence of composite complications compared to less restrictive strategies in open thoracotomy: A retrospective cohort study. Scientific Reports, 2020; 10. https://doi.org/10.1038/s41598-020-65532-w
3. Messina A, Robba C, Calabro L, Zambelli D, Iannuzzi, Molinari E, Scarano S, Battaglini D, Baggiani M, De Mattei G, Saderi L, Sotgiu G, Pelosi P and Cecconi M. Peri-operative liberal versus restrictive fluid strategies and postoperative outcomes: a systematic review and metanalysis on randomized-controlled trials in major abdominal elective surgery. Critical Care, 2021; 25:205-218. https://doi.org/10.1186/s13054-021-03629-y