Objectives: To compare the influence of 2 volumes of fluid, integrated with goal-directed fluid therapy, on hypovolemia (a key trigger of tissue hypoperfusion) and central venous oxygen saturation (Scvo₂) and to assess their relationships with postoperative morbidity.
Design, setting, and patients: A prospective, randomized trial of 70 consecutive patients undergoing major abdominal surgery.
Interventions: Patients were randomly assigned to 6 mL/kg/h of crystalloid (a restrictive fluid strategy) or 12 mL/kg/h of crystalloid (a more conservative fluid strategy). In both groups, a fluid bolus was administered when respiratory variation in peak aortic flow velocity (ΔPV) was greater than 13%. Data on hypovolemia (ΔPV > 13%), Scvo₂, and postoperative complications were recorded for all patients.
Main outcome measures: Overall incidence of postoperative complications, especially anastomotic leak and sepsis.
Results: Overall incidence of complications, including postoperative anastomotic leak and sepsis, was higher in the restrictive group than in the conservative group (all P < .05). The number of patients with hypovolemia increased significantly in the restrictive group compared with the conservative group (P < .001). The perioperative mean Scvo₂ (P = .02) and mean minimum Scvo₂ (P = .04) were significantly lower in the restrictive group than in the conservative group. Multivariate analysis showed that both hypovolemia and mean minimum Scvo₂ were independently associated with anastomotic leak and sepsis.
Conclusions: Excessive fluid restriction increased the level of hypovolemia, leading to reduced Scvo₂ and thereby increased incidence of postoperative complications. Excessive fluid restriction should be applied cautiously in surgical patients.
Trial registration: clinicaltrials.gov Identifier: NCT00852449.