Trial Summary




This will be a large, randomized, parallel-group, controlled trial. After stratification by centre and planned ICU/HDU admission (or not), patients will be randomly assigned from a computer-generated list (1:1) to either a Restrictive or Liberal fluid Group.

Group 1 = Restrictive fluid regimen (intraoperative and 1st 24 h ≈2.5 L)

Group 2 = Liberal fluid regimen (intraoperative and 1st 24 h ≈5.5 L)


Sample Size:

2800 patients


Study Duration:

3 years


Primary Endpoint

Disability-free survival up to 1 year: survival and freedom from new-onset disability, the latter being a persistent(>6 months) reduction in functional status as defined by a 4-point or greater reduction in the 12-item version of WHODAS. Disability will be assessed by the participant, but if unable then we will use the proxy’s report. The date of onset of new disability will be recorded.

Interim analysis (& DSMC review): at n= 1000 and 2000 patients



To investigate the effectiveness of fluid restriction (vs. liberal), and the possible effect-modification of goal-directed therapy (eg. oesophageal Doppler, Flotrac®). The first will be randomly assigned; the latter will be measured covariates according to local practices and beliefs.

The optimal fluid regimen and haemodynamic (or other) targets for patients undergoing major surgery are based on rationales that are not supported by strong evidence. Practices vary substantially; guidelines are vague, small trials and meta-analyses are contradictory. The strongest and most consistent evidence, and biological plausability regarding tissue oedema, supports a restrictive fluid strategy. There is less (and more contradictory) evidence supporting goal-directed therapy using a flow-directed device and/or dopexamine, and use and choice of colloids. A large, definitive clinical trial evaluating perioperative fluid replacement in major surgery is required.


Study Hypotheses

A restrictive fluid regimen for adults undergoing major abdominal surgery leads to reduced complications and improved disability-free survival when compared with a liberal fluid regimen.

Secondary hypotheses: The effects of fluid restriction are similar whether or not goal-directed therapy is used (assessed as a statistical test of interaction). A restrictive fluid regimen will reduce a composite of 30-day septic complications and mortality.

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