More evidence needed as to the best concentration of crystalloid to use in resuscitation fluids

Fluid resuscitation is usually given when a patient has lost a lot of blood, but there is continuing uncertainty as to the best sort of fluid to use. Some of the fluids used contain substances classified as "crystalloids", but should the concentration of crystalloids in the fluid be about the same as their concentration in human blood ("isotonic") or higher ("hypertonic")? It is commonly believed that hypertonic crystalloid is the more effective at increasing blood volume but that there could be some disadvantages to using it. This review has assessed the evidence from studies that compared the use of the two types of fluid with patients who had been injured or burned, or were having surgery. Not enough evidence is available, however, to decide which crystalloid concentration is best. More research is needed.

Authors' conclusions: 

This review does not give us enough data to be able to say whether hypertonic crystalloid is better than isotonic and near isotonic crystalloid for the resuscitation of patients with trauma or burns, or those undergoing surgery. However, the confidence intervals are wide and do not exclude clinically significant differences. Further trials which clearly state the type and amount of fluid used and that are large enough to detect a clinically important difference are needed.

Read the full abstract...

Hypertonic solutions are considered to have a greater ability to expand blood volume and thus elevate blood pressure and can be administered as a small volume infusion over a short time period. On the other hand, the use of hypertonic solutions for volume replacement may also have important disadvantages.


To determine whether hypertonic crystalloid decreases mortality in patients with hypovolaemia.

Search strategy: 

We searched the Cochrane Injuries Group's specialised register, MEDLINE, EMBASE, The Cochrane Library, issue 3, 2007, The National Research Register issue 3, 2007 and the British Library's Electronic Table of Contents ZETOC. We also checked reference lists of all articles identified. The searches were last updated in October 2007

Selection criteria: 

Randomised trials comparing hypertonic to isotonic and near isotonic crystalloid in patients with trauma or burns or who were undergoing surgery.

Data collection and analysis: 

Two authors independently extracted the data and assessed the quality of the trials.

Main results: 

Fourteen trials with a total of 956 participants are included in the meta-analysis. The pooled relative risk (RR) for death in trauma patients was 0.84 (95% confidence interval [CI] 0.69 to1.04); in patients with burns 1.49 (95% CI 0.56 to 3.95); and in patients undergoing surgery 0.51 (95% CI 0.09 to 2.73). In the one trial that gave data on disability using the Glasgow outcome scale, the relative risk for a poor outcome was 1.00 (95% CI 0.82 to 1.22).