Colloids versus crystalloids for fluid resuscitation in critically ill patients.

BACKGROUND: Colloid solutions are widely used in fluid resuscitation of critically ill patients. There are several choices of colloid and there is ongoing debate about the relative effectiveness of colloids compared to crystalloid fluids. OBJECTIVES: To assess the effects on mortality of colloids compared to crystalloids for fluid resuscitation in critically ill patients. SEARCH STRATEGY: We searched the Injuries Group specialised register, Cochrane Controlled Trials Register, MEDLINE, EMBASE and BIDS Index to Scientific and Technical Proceedings and checked the reference lists of trials and review articles. SELECTION CRITERIA: All randomised and quasi-random trials of colloids compared to crystalloids, in patients requiring volume replacement. Cross-over trials and trials in pregnant women and neonates were excluded. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and rated quality of allocation concealment. Trials with a 'double-intervention' such as those, which compared colloid in hypertonic crystalloid to isotonic crystalloid, were analysed separately. The analysis was stratified according to colloid type and quality of allocation concealment. MAIN RESULTS: Colloids compared to crystalloids: Albumin or plasma protein fraction: Eighteen trials reported data on mortality, including a total of 641 patients. The pooled relative risk from these trials was 1.52 (95% confidence interval 1.08 to 2.13). The risk of death in the albumin treated group was 6% higher than in the crystalloid treated group (1% to 11%). When the trial with poor quality allocation concealment was excluded the pooled relative risk was 1.34 (0.95 to 1.89). Hydroxyethylstarch: Seven trials compared hydroxyethylstarch with crystalloids including a total of 197 randomised participants. The pooled relative risk was 1.16 (0.68 to 1.96). Modified gelatin: Four trials compared modified gelatin with crystalloid including a total of 95 randomised participants. The pooled relative risk was 0.50 (0. 08 to 3.03). Dextran: Eight trials compared dextran with a crystalloid including a total of 668 randomised participants. The pooled relative risk was 1.24 (0.94 to 1.65). Colloids in hypertonic crystalloid compared to isotonic crystalloid: Eight trials compared dextran in hypertonic crystalloid with isotonic crystalloid, including 1283 randomised participants. The pooled relative risk was 0.88 (0.74 to 1.05). REVIEWER'S CONCLUSIONS: There is no evidence from randomised controlled trials that resuscitation with colloids reduces the risk of death compared to crystalloids in patients with trauma, burns and following surgery. As colloids are not associated with an improvement in survival, and as they are more expensive than crystalloids, it is hard to see how their continued use in these patient types can be justified outside the context of randomised controlled trials.