The biochemical effects of restricting chloride-rich fluids in intensive care.

OBJECTIVE

To determine the biochemical effects of restricting the use of chloride-rich intravenous fluids in critically ill patients.

DESIGN

Prospective, open-label, before-and-after study.

SETTING

University-affiliated intensive care unit.

PATIENTS

A cohort of 828 consecutive patients admitted over 6 months from February 2008 and cohort of 816 consecutive patients admitted over 6 months from February 2009.

INTERVENTIONS

We collected biochemical and fluid use data during standard practice without clinician awareness. After a 6-month period of education and preparation, we restricted the use of chloride-rich fluids (0.9% saline [Baxter, Sydney, Australia], Gelofusine [BBraun, Melsungen, Germany], and Albumex 4 [CSL Bioplasma, Melbourne, Australia]) in the intensive care unit and made them available only on specific intensive care unit specialist prescription.

MEASUREMENTS AND MAIN RESULTS

Saline prescription decreased from 2411 L in the control group to 52 L in the intervention group (p < .001), Gelofusine from 538 to 0 L (p < .001), and Albumex 4 from 269 to 80 L (p < .001). As expected, Hartmann's lactated solution prescription increased from 469 to 3205 L (p < .001), Plasma-Lyte from 65 to 160 L (p < .05), and chloride-poor Albumex 20 from 87 to 268 L (p < .001). After intervention, the incidence of severe metabolic acidosis (standard base excess <-5 mEq/L) decreased from 9.1% to 6.0% (p < .001) and severe acidemia (pH <7.3) from 6.0% to 4.9% (p < .001). However, the intervention also led to significantly greater incidence of severe metabolic alkalosis (standard base excess >5 mEq/L) and alkalemia (pH >7.5) with an increase from 25.4% to 32.8% and 10.5% to 14.7%, respectively (p < .001). The time-weighted mean chloride level decreased from 104.9 ± 4.9 to 102.5 ± 4.6 mmol/L (p < .001), whereas the time-weighted mean standard base excess increased from 0.5 ± 4.5 to 1.8 ± 4.7 mmol/L (p < .001), mean bicarbonate from 25.3 ± 4.0 to 26.4 ± 4.1 mmol/L (p < .001) and mean pH from 7.40 ± 0.06 to 7.42 ± 0.06 (p < .001). Overall fluid costs decreased from $15,077 (U.S.) to $3,915.

CONCLUSIONS

In a tertiary intensive care unit in Australia, restricting the use of chloride-rich fluids significantly affected electrolyte and acid-base status. The choice of fluids significantly modulates acid-base status in critically ill patients.