MARCH 21, 2025
Originally published by our sister publication Anesthesiology News
Finding the right amount of fluid to administer before complex spinal surgery has been elusive for decades. Too much fluid can increase the risk for postoperative complications, such as gastrointestinal issues and pneumonia, while too little fluid may elevate the risk for mortality during surgery.
However, new research from Cleveland Clinic suggests that the ideal fluid amount is 1.865 L. Fluid administered above this threshold
Originally published by our sister publication Anesthesiology News
Finding the right amount of fluid to administer before complex spinal surgery has been elusive for decades. Too much fluid can increase the risk for postoperative complications, such as gastrointestinal issues and pneumonia, while too little fluid may elevate the risk for mortality during surgery.
However, new research from Cleveland Clinic suggests that the ideal fluid amount is 1.865 L. Fluid administered above this threshold raises the risk for complications, while intraoperative hypotension further increases these risks.
The study is the first to demonstrate that both i ntraoperative hypotension and excessive fluid overload significantly contribute to postoperative complications in patients who are undergoing complex spinal surgeries (Anesth Analg 2024 Dec 17. doi:10.1213/ANE.0000000000007358).
“We started looking at our data and it is stunning that for the first time ever, we demonstrated that there is an inflection point of fluid overload,” said principal investigator Ehab Farag, MD, a professor of anesthesiology at Cleveland Clinic Lerner College of Medicine, and the director of clinical research in anesthesiology at Cleveland Clinic, in Ohio. “If we look at fluid balance, more than 1,800 mL, you start to have complications.”
Threshold Found For Fluid Volume
The study examined 6,243 patients who underwent 6,998 complex spine surgeries between 2012 and 2022. The mean net fluid administration for these patients was 2,100 mL.
The findings showed a significant change at 1,865 mL of net fluid administration. For every 500 mL above this threshold, the odds of postoperative complications increased by 1.16 times (95% CI, 0.77-0.98; P=0.026). Below the change point, the odds of complications decreased to 0.87 (95% CI, 0.77-0.98; P=0.026). Intraoperative hypotension occurred in 29% of the surgeries studied.
Patients with excessive fluid administration or intraoperative hypotension were more likely to experience postoperative pulmonary complications, and acute kidney injuries, myocardial infarction, stroke and ICU admission.
For every 500 mL of fluid increase, the odds of postoperative pulmonary complications rose by 1.12 times (95% CI, 1.07-1.18; P<0.0001).
A History of Fluid Use
The debate on how much fluid to administer during surgery has persisted for decades. Elizabeth A.M. Frost, MD, a clinical professor of anesthesiology at the Icahn School of Medicine at Mount Sinai, in New York City, explained that prior to the 1950s, anesthesiologists did not administer fluids before surgery.
This practice led to higher mortality rates during surgeries. However, by 1957, the medical community largely adopted fluid administration, believing it could improve survival rates during surgery.
Despite the success in reducing mortality during the actual procedures, complications in the 30 days following surgery became more common, including gastrointestinal issues, pulmonary problems and pneumonia.
In response, researchers in the 2010s began examining the effects of fluid overload and its potential to cause additional complications, such as vision loss. The Cleveland Clinic study represents a natural progression in these investigations.
“I think this article is significant because it is not only questioning, but it is consolidating and verifying a lot of information that has been built up over the last 60 to 70 years. I think it is very important,” Frost said.
Moving Forward
While Frost praised the study for identifying a specific fluid threshold, she believes future research should explore the effects of age and other variables, such as comorbidities, on fluid management.
“I’d like to see Farag push that mean arterial blood pressure up because I don’t think he is taking age into account in his study,” Frost said. “It’s a good study; it has to be tightened up a lot more as I see it. We got to narrow this down a lot.”
She added that if future studies confirm an optimal fluid level, the debate about fluid administration will likely become less contentious.
Farag and his team hope that their findings will encourage further research to refine fluid management protocols, especially as more data on age and other demographic factors are considered.
By Kenny Walter
Farag and Frost are members of the Anesthesiology News editorial advisory board.
