Targeting oliguria reversal in perioperative restrictive fluid management does not influence the occurrence of renal dysfunction: A systematic review and meta-analysis

BACKGROUNDInterest in perioperative fluid restriction has increased, but it could lead to hypovolaemia. Urine output is viewed as a surrogate for renal perfusion and is frequently used to guide perioperative fluid therapy. However, the rationale behind targeting oliguria reversal - achieving and maintaining urine output above a previously defined threshold by additional fluid boluses - is often questioned.OBJECTIVEWe assessed whether restrictive fluid management had an effect on oliguria, acute renal failure (ARF) and fluid intake. We also investigated whether targeting oliguria reversal affected these parameters.DESIGNSystematic review of randomised controlled trials with meta-analyses. We used the definitions of restrictive and conventional fluid management as provided by the individual studies.DATA SOURCESWe searched MEDLINE (1966 to present), EMBASE (1980 to present), and relevant reviews and articles.ELIGIBILITY CRITERIAWe included randomised controlled trials with adult patients undergoing surgery comparing restrictive fluid management with a conventional fluid management protocol and also reporting the occurrence of postoperative ARF.RESULTSWe included 15 studies with a total of 1594 patients. There was insufficient evidence to associate restrictive fluid management with an increase in oliguria [restrictive 83/186 vs. conventional 68/230; odds ratio (OR) 2.07; 95% confidence interval (CI), 0.97 to 4.44; P=0.06; I-2=23.7%; N-studies=5]. The frequency of ARF in restrictive and conventional fluid management was 20/795 and 20/799, respectively (OR 1.07; 95% CI, 0.60 to 1.92; P=0.8; I-2=17.5%; N-studies=15). There was no statistically significant difference in ARF occurrence between studies targeting oliguria reversal and not targeting oliguria reversal (OR 0.31; 95% CI, 0.08 to 1.22; P=0.088). Intraoperative fluid intake was 1.89l lower in restrictive than in conventional fluid management when not targeting oliguria reversal (95% CI, -2.59 to -1.20l; P<0.001; I-2=96.6%; N-studies=7), and 1.63l lower when targeting oliguria reversal (95% CI, -2.52 to -0.74l; P<0.001; I-2=96.6%; N-studies=6).CONCLUSIONOur data suggest that, even though event numbers are small, perioperative restrictive fluid management does not increase oliguria or postoperative ARF while decreasing intraoperative fluid intake, irrespective of targeting reversal of oliguria or not.