Evaluation of blood transfusion effects on mixed venous oxygen saturation and lactate levels in patients with systemic inflammatory response syndrome (SIRS)/sepsis

Introduction

Blood transfusions continue to be a controversial therapy in intensive care units, mostly in patients with SIRS/sepsis, with conflicting thresholds for transfusion and different results in the literature. The present study is aimed at evaluating the effects of blood transfusion in two parameters of organ perfusion, mixed venous oxygen saturation (SvO₂) and serum lactate levels in patients with SIRS/sepsis who presented with hemoglobin levels < 9.0 g/dl.

Methods

All patients admitted to the intensive care unit with SIRS/sepsis, as defined by Consensus Conference 1992, and hemoglobin levels < 9.0 g/dl were included. Hemoglobin levels, mixed venous oxygen saturation and lactate levels were collected before (BT) and up to 1 hour after blood transfusion (AT). These variables were analyzed through the paired Student t test and results were considered significant if P ≤ 0.005.

Results

Twenty-nine patients (17 male, 12 female) with mean age of 61.9 ± 15.1 years (21–85 years) and a mean APACHE II score of 12.5 ± 3.75 (7–21) were transfused with a mean of 1.41 packed red cell units. Although a significant increase in hemoglobin levels was achieved by blood transfusion (BT, 8.14 ± 0.64 and AT, 9.4 ± 0.33; P > 0.0001), this was not accompanied by a significant change in lactate levels (BT, 1.87 ± 1.22 and AT, 1.56 ± 0.28; P = 0.28) or in SvO₂ (BT, 64.3 ± 8.52 and AT, 67.4 ± 6.74; P = 0.13). The results were similar when the analysis was performed only with those patients with hemoglobin levels < 8.0 g/dl (n = 9).

Conclusions

These results suggests that blood transfusions, despite a significant increase in hemoglobin levels, are not associated with an improvement in tissue oxygenation in patients with SIRS/sepsis with hemoglobin levels < 9 g/dl.