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Evaluation of red blood cell transfusion effects in lactate and central venous oxygen saturation in patients with severe sepsis and septic shock

Introduction

Red blood cell (RBC) transfusion is very often performed in critically ill patients despite its potential complications. Its effects on oxygen delivery and microcirculation are not well known. This study aimed at evaluating RBC effects in blood lactate levels (LAC) and central venous oxygen saturation (SvcO2) in patients with severe sepsis and septic shock.

Methods

A prospective study enrolling patients admitted to an ICU at a university hospital with severe sepsis and septic shock presenting hemoglobin (Hb) levels below 9.0 g/dl. These patients were randomized for maintaining Hb >9 g/dl (Group 1) or >7 g/dl (Group 2). Before (preT) and at least 1 hour after each transfusion (postT) LAC, SvcO2 and Hb data were collected. Data were analysed by analysis of variance, paired t test and paired Wilcoxon test. Results were considered significant if P ≤ 0.05.

Results

Thirty-six transfusions were evaluated in 21 patients (mean age 59.0 ± 15.8 years, 11 females/10 males) with APACHE II score of 13.8 ± 4.1. Each group included 18 patients. The levels of Hb preT and postT were 7.51 ± 1.03 and 8.48 ± 1.15 (P < 0.05). There was a significant difference between preT and postT SvcO2 (70.9 ± 8.66 and 73.6 ± 7.2, P = 0.01) but not in LAC levels (24.1 ± 8.9 and 22.9 ± 7.6, P = 0.45). When groups were analyzed separately, only in Group 2 was a significant difference found (P = 0.0005 and 0.05, respectively for SvcO2 and LAC). In 10 transfusions a worsening of SvcO2 postT was observed and all these patients had preT SvcO2 > 70%. Although there was no significant correlation between a worsening in SvcO2 and preT Hb, eight of these patients were allocated to Group 1. Another 13 transfusions were done with a SvcO2 preT < 70, and 10 of them improved (> 5%) after transfusion (mean percentage of improvement = 18.9%). Only four of these patients were allocated to Group 1. Patients with high levels of preT LAC (n = 21) only improved (reduction > 10%) in 42.9% of cases. A total 53.3% of patients with normal preT LAC levels worsened (rising > 10%) postT. The mean preT Hb from these patients was 8.18 ± 0.9.

Conclusion

In patients with SvcO2 < 70 and/or Hb < 7.0 g/dl, transfusion seems to result in an improvement of perfusion parameters. However, in patients with SvcO2 > 70 or normal lactate levels, transfusion seems to impair tissue perfusion.

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Mazza, B., Assuncao, M., Freitas, F. et al. Evaluation of red blood cell transfusion effects in lactate and central venous oxygen saturation in patients with severe sepsis and septic shock. Crit Care 11, P411 (2007). https://doi.org/10.1186/cc5571

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Keywords

  • Septic Shock
  • Severe Sepsis
  • Blood Lactate
  • Lactate Level
  • Perfusion Parameter