'Liberal' vs. 'restrictive' perioperative fluid therapy - a critical assessment of the evidence

Background Several studies have assessed the effect of a 'liberal' vs. a 'restrictive' perioperative fluid regimen on post-operative outcome. The literature was reviewed in order to provide recommendations regarding perioperative fluid regimens. Methods A PubMed search identified randomized clinical trials and cited studies, comparing two different fixed fluid volumes on post-operative clinical outcome in major surgery. Studies were assessed for the type of surgery, primary and secondary outcome endpoints, the type and volume of administered fluid and the definition of the perioperative period. Also, information regarding perioperative care and type of anaesthesia was assessed. Results In the seven randomized studies identified, the range of the liberal intraoperative fluid regimen was from 2750 to 5388 ml compared with 998 to 2740 ml for the restrictive fluid regimen. The period for fluid therapy and outcome endpoints were inconsistently defined and only two studies reported perioperative care principles and discharge criteria. Three studies found an improved outcome (morbidity/hospital stay) with a restrictive fluid regimen whereas two studies found no difference and two studies found differences in the selected outcome parameters. Conclusion Liberal vs. restrictive fixed-volume regimens are not well defined in the literature regarding the definition, methodology and results, and lack the use of or information on evidence-based standardized perioperative care-principles (fast-track surgery), thereby precluding evidence-based guidelines for procedure-specific perioperative fixed-volume regimens. Optimization of perioperative fluid management may include a combination of fixed crystalloid administration to replace extra-vascular losses and avoiding fluid excess, together with individualized goal-directed colloid administration to maintain a maximal stroke volume.