Extracellular fluid variations during a fluid challenge: a comparison of normal saline (NS) and hydroxyethyl starch (HES) in stressed patients

The controversy regarding the use of crystaloids or colloids for fluid resuscitation of critically ill patients continues. Fluid remaining in the vascular compartment would have an obvious advantage. We used bioimpedance, a technique allowing assessment of body cell mass and extracellular water, to compare NS and HES, a relatively new colloid.

Methods

Twenty-two critically ill patients requiring a fluid challenge were randomized to receive other 500 ml of NS or 500 ml of HES 10% (Fresenius, Germany). Vital signs (heart rate, systolic blood pressure, central venous pressure (CVP) and urine output) were noted before and immediately after the challenge. Bioimpedance changes, using a tetra-polar system working on 800 microamperes and 50 Khz (BIA-109), Ackern) were measured before and after the fluid challenge. Body cell mass (BCM) and extracellular water (ECW) were then derived. Results are expressed as the mean ± SD.

Results

Ten patients (mean age 57 ± 18.6 years) received HES 10% and twelve (mean age 56.9 ± 13.9 years) received NS. There were no significant differences between the two groups regarding pre- and post-challenge hemodynamic parameters, in particular change in CVP. Bioimpedance measurements before and after fluid challenge were as follows:

Conclusion

We showed that there is an increase in extracellular water in critically patients receiving a fluid challenge with normal saline but not with HES. This could indicate a beneficial effect of HES on extravascular extravasation of water in stressed patients.

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