Assisted Fluid Management for Major Liver Surgery: Comment

To the Editor: Recently, Coeckelenbergh et al.1 published an article exploring the use of the Acumen assisted fluid management system (Edwards Lifesciences, USA) in major hepatic resection, specifically examining its ability to reduce arterial lactate at the end of the surgery in comparison to more restrictive fluid therapy. The findings indicated that patients undergoing major hepatic resection who received fluid management guided by a decision support system demonstrated lower arterial lactate at the end of the procedure compared to those following a more restrictive fluid therapy strategy. Upon careful review of this article, several questions have arisen that warrant discussion. First, lactate is primarily cleared by the liver (approximately 60%),2 and thus, variations in liver function among patients may influence the primary outcome of the study, which is the concentration of lactate at the end of the surgery. Although the authors provided baseline lactate levels, the inclusion of preoperative indicators commonly used to reflect liver function, such as aspartate aminotransferase and alanine aminotransferase, would enhance the completeness of the baseline data. Additionally, metformin inhibits gluconeogenesis, thereby suppressing the conversion of lactate to glycogen.3 Therefore, preoperative use of metformin may affect the primary outcome. The article also fails to specify the types of antidiabetic medications used by the two groups and the timing of their last administration. Clarifying these issues contributes to the attainment of more reliable conclusions. Second, the authors noted that after hepatic resection, physicians are free to administer fluids. The median fluid volumes administered to the two groups after hepatic resection were 2,000 ml and 1,800 ml, respectively. However, the study does not specify the types of fluids used (such as sodium lactate or sodium acetate) or their ratios. It should be emphasized that the infusion of lactated Ringer’s solution, which contains lactate, may result in different lactate levels at the end of the surgery due to variations in the volume administered. Finally, the standardized mean differences of the baseline data in this study ranged from 0.00 to 0.32. Currently, most studies suggest that a standardized mean difference of less than 0.1 indicates that the two groups are balanced.4 Therefore, in this study, it is recommended that residual imbalance issues be addressed in the primary analysis or sensitivity analysis. This approach is anticipated to yield more robust results, as substantial discrepancies between the baselines can undermine the reliability of the conclusions drawn. Competing Interests The authors declare no competing interests.