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Effects of Fluid Resuscitation with Colloids Versus Crystalloids on Mortality in Critically Ill Patients Presenting with Hypovolemic Shock: the CRISTAL Randomized Trial
Study Question: Is there a difference in mortality with colloid versus crystalloid fluid resuscitation in critically ill patients with hypovolemic shock?
Study Description: This was a multicenter, randomized trial comparing colloid (gelatins, dextrans, hydroxyethyl starches, or 4% or 20% albumin) with crystalloid fluid administration (isotonic or hypertonic saline or lactated ringers solution) in critically ill patients with hypovolemic shock. Hypovolemic shock was defined as the combination of hypotension, evidence for low filling pressures and cardiac index, and signs of tissue hypoperfusion or hypoxia. Patients who were treated in the colloid group most commonly received hydroxyethyl starches (70%) whereas patients in the crystalloid group most commonly received isotonic saline (86%).
Results: A total of 2,857 patients were included in the study (colloid, n = 1414; crystalloid, n = 1443). The population was predominantly septic (54%), rather than admitted with trauma (6%) or hypovolemic shock (39%). Fluid administration prior to intensive care unit (ICU) admission (within the past 12 hours) was recorded. 37% of patients in the colloid group receiving crystalloids with (median dose 1000 mL) compared with 48% of patients in the crystalloid group receiving colloids (median dose 1000 mL). Median cumulative fluid volume for the first 7 ICU days was 2,000 mL in the colloid group vs. 3,000 mL in the crystalloid group. Median duration of treatment was 2 days. No difference was found in 28-day mortality (25.4% colloid vs. 27% crystalloids, p = 0.26). At 90 days, however, there were fewer deaths in the colloid group (30.7% vs. 34.2%, p = 0.03). There were no differences between groups in the amount of blood product transfused, renal replacement therapy employed, rates of organ failure, or ICU or hospital length of stay. Colloid resuscitation resulted in more ventilator-free days (14.6 vs. 13.5, p = 0.01) and vasopressor-free days (16.2 vs. 15.2, p = 0.03) within the first 28 days.
Conclusion(s): There was no difference in 28-day mortality with colloids compared with crystalloids in ICU patients with hypovolemic shock. Mortality at 90 days was lower in patients who received colloids, but this outcome requires further evaluation before conclusions can be reached.
Perspective: This colloid versus crystalloid trial compared a class effect rather than individual agents from each class; however, two major agents were most commonly utilized including hydroxyethyl starches and isotonic saline. This has important implications to the generalization of the study’s results since differences exist amongst individual crystalloid and colloid agents including efficacy and safety profile. Additionally, the impact of fluid administration prior to ICU admission (within the past 12 hours) may have impacted results. Careful consideration for efficacy, safety, and cost should continue to guide fluid resuscitation in hypovolemic patients, taking into consideration results of this current study along with other published evidence. Although the statistically significant difference in ventilator- and vasopressor-free days is interesting, it is hard to argue that the size of the difference is clinically significant.