Haemoglobin concentration and volume of intravenous fluids in septic shock in the ARISE trial

Abstract

BackgroundIntravenous fluids may contribute to lower haemoglobin levels in patients with septic shock. We sought to determine the relationship between the changes in haemoglobin concentration and the volume of intravenous fluids administered during resuscitation from septic shock.MethodsWe performed a retrospective cohort study of patients enrolled in the Australasian Resuscitation in Sepsis Evaluation (ARISE) trial who were not transfused red blood cells (N = 1275). We determined the relationship between haemoglobin concentration, its change over time and volume of intravenous fluids administered over 6, 24 and 72 h using univariate and multivariate analysis.ResultsMedian (IQR) haemoglobin concentration at baseline was 133 (118–146) g/L and decreased to 115 (102–127) g/L within the first 6 h of resuscitation (P < 0.001), 110 (99–122) g/L after 24 h, and 109 (97–121) g/L after 72 h. At the corresponding time points, the cumulative volume of intravenous fluid administered was 1.3 (0.7–2.2) L, 2.9 (1.8–4.3) L and 4.6 (2.7–7.1) L. Haemoglobin concentration and its change from baseline had an independent but weak association with intravenous fluid volume at each time point (R2 < 20%, P < 0.001). After adjusting for covariates, each litre of intravenous fluid administered was associated with a change in haemoglobin concentration of − 1.0 g/L (95% CI −1.5 to −0.6, P < 0.001) at 24 h and − 1.3 g/L (− 1.6 to − 0.9, P < 0.001) at 72 h.ConclusionsHaemoglobin concentration decreases during resuscitation from septic shock, and has a significant but weak association with the volume of intravenous fluids administered.Electronic supplementary materialThe online version of this article (10.1186/s13054-018-2029-6) contains supplementary material, which is available to authorized users.

Anemia in hospitalized patients: an overlooked risk in medical care

“…Plasma volume expansion with resultant hemodilution can take place with administration of vasodilators and intravenous fluids. Hb levels can fluctuate and fall because of various stressors, disease states, and neuroendocrine responses . In some settings, the Hb level may increase or decrease without a change in RBC mass.…”

The relationship between the decrease in haemoglobin concentration and the volume of fluids administered during resuscitation from septic shock may not be so “weak”

“…In a retrospective analysis of the database of the ARISE trial [ 1 ], Maiden et al [ 2 ] found an independent though weak association between haemoglobin concentration (Hgb) and the volume of fluids administered during resuscitation from septic shock. The volume infused accounted for less than 20% of the observed decrease in the Hgb, but the explanations for this decrease, other than haemodilution, seem unlikely even to the authors themselves [ 2 ]. A closer look at this study suggests a much stronger association between the volume infused and Hgb decrease.…”

“…Of the 1600 ARISE patients, Maiden et al excluded 281 who received blood transfusions [ 2 ]. It may well be that the transfused patients were those with the greatest degree of haemodilution, the low Hgb prompting the decision to transfuse.…”

“…Although the ARISE trial was not aimed at reporting Hgb values during the first 6 h of resuscitation, Maiden et al report such values from roughly 200 patients [ 2 ]. Many of these patients seem to have had no fluids administered during the first hours, and yet have a significant decrease in Hgb of more than 2 g/dL (Fig.…”

“…1 ). However, all patients in the ARISE trial received about 35 ml/kg prior to randomisation [ 1 ], a fact that explains the initial observed decrease in Hgb in Maiden et al’s study [ 2 ]. Taking this significant amount of fluids into consideration when calculating the association between the infused fluids and Hgb decrease would have made this association much stronger.…”