The influence of the preoperative immune response on blood transfusion requirements in patients undergoing cardiac surgery.

OBJECTIVE

The purpose of this study was to evaluate the influence of preoperative type I and II immune responses on blood transfusion requirements.

DESIGN

A prospective and observational trial.

SETTING

A postcardiac surgery unit of a university hospital.

PARTICIPANTS

Seventy-one consecutive patients undergoing elective cardiac surgery.

INTERVENTIONS

Blood samples drawn for laboratory analysis and immunologic study.

MEASUREMENTS AND MAIN RESULTS

Patients were divided into 2 groups according to blood transfusion requirements: < or = 2 units (n = 35) and >2 units of red blood cells (n = 36). The preoperative immune response was assessed by flow cytometry, measuring the proportion of CD4+ T helper cells producing cytokines, including Th1 response (interferon-gamma and tumor necrosis factor-alpha [TNF-alpha]) and Th2 response (interleukin 4 and 10). Two logistic regression analyses (including and not including immunologic variables) were used to select and weight perioperative variables associated with an increased risk of transfusion. Three variables were found to be independent predictors of transfusion requirements when immunologic variables were not included: preoperative platelet count, preoperative hemoglobin, and hypertension. When all the variables were included, preoperative hemoglobin, cardiopulmonary bypass time, and the preoperative proportion of CD4+ T cells producing TNF-alpha were associated with an increased risk of transfusion (Hosmer-Lemeshow, 0.33; c-index, 0.93), but preoperative platelet count and hypertension were not.

CONCLUSIONS

A low preoperative Th1 immune response, as assessed by the proportion of CD4+ T-helper-producing TNF-alpha, was associated with a higher blood transfusion rate.