Nine RCTs were included in the review (n=971 patients). Trials were generally of moderate to high quality (scores 8 to 10 points; the maximum possible score was not reported). All of the trials reported a power calculation but they used different primary endpoints. Sample size ranged from 20 to 253. Seven trials reported standardised perioperative treatment.
Standard versus restrictive fluid administration (four RCTs, n=393 patients): Restrictive fluid administration was associated with a statistically significant reduction in postoperative morbidity (OR 0.41, 95% CI 0.22 to 0.77; I2=37%; NNT 6, 95% CI 4 to 7). There was significant reduction in morbidity when the period over which restricted fluid was administered included the intraoperative period (OR for perioperative restriction 0.35, 95% CI 0.18 to 0.70; OR for intraoperative restriction 0.46, 95% CI 0.21 to 0.99). There was no significant reduction in morbidity when restricted fluid was only given in the postoperative period.
Standard versus supplemental fluid administration: There was no significant reduction in overall morbidity between standard and supplemental fluid administration in the one study reporting this outcome.
Fluid administration strategy (three RCTs, n=288 patients): Goal-directed fluid administration based on oesophageal Doppler-guidance was associated with a statistically significant reduction in postoperative morbidity (OR 0.43, 95% CI 0.26 to 0.71; I2=0%; NNT 6, 95% CI 4 to 12).
The funnel plot showed no evidence of relevant publication bias.
There were no significant differences for secondary outcomes (results were reported in the review).