Background: Transfusion of blood and blood products has been associated with immunologic modulation and increased risk of infection. While the total volume of blood transfusions has been shown to increase risk, the need for large volume transfusions in hemorrhaging patients has not been examined as a risk factor. We evaluate a non-trauma surgical critical care population to identify independent risk factors for infection and hypothesize that massive transfusion (³ 10 U RBC in 24hours) is not independently associated with hospital-acquired infections.

Methods: A retrospective study of adult critical care patients entered into a prospectively collected surgical critical care database between 01/2005 and 06/2008 was performed to identify risk factors for nosocomial infection. Massive transfusion (MT) was defined as =10 units RBC transfused in a 24-hour period following admission to the ICU. Prospective surveillance using standard NHSN definitions for Hospital-acquired infections (HAI) was performed. Univariate analysis identified factors associated with development of HAI. Using HAI as the primary endpoints, multiple logistic regression analysis was performed to identify the independently associated covariates.

Results: 3,791 patients were admitted during the study period and comprised the study group. 2,667 (70%) received no transfusion, and 1,056 (28%) received < 10U RBC during their entire ICU admission. 68 (1.8%) received MT. MT patients were predominantly male, were more likely to develop HAI, and had a longer ICU length of stay (LOS), higher APACHE II scores, and ICU mortality (p<0.001). After adjusting the study group for age, gender, BMI, mechanical ventilation, total blood volume, and APACHE II, MT was not significantly associated with HAI, specifically; blood stream infection (BSI), pneumonia (PNA), or surgical site infection (SSI), however was independently associated with urinary tract infections (UTI).

Association of MT with HAI

	N (%)	OR (95% CI)	Adj.* OR (95% CI)
HAI	242 (6.4%)	7.5 (4.4, 12.6)	1.0 (0.4, 3.0)
BSI	49 (1.2%)	8.3(3.4, 20.1)	1.7 (0.2, 11.3)
PNA	137 (3.6%)	9.2(5.1, 15.5)	0.3 (0.1, 1.2)
SSI	56 (1.5%)	3.2(1.0, 10.4)	0.0 (0.0, 1.2)
UTI	47 (1.2%)	8.6 (3.5, 20.9)	3.9 (0.6, 25.6)

HAI, hospital-acquired infections; OR , odds ratio; CI, confidence interval; BSI, blood stream infection; PNA, pneumonia; SSI, surgical site infection; UTI, urinary tract infection; *adjusted OR to age, gender, ICU LOS, BMI, mechanical ventilation, total blood volume, and Acute Physiology and Chronic Health Evaluation II. ROC AUC = 0.79 in all models.

Conclusion: Massive transfusion is not solely responsible for hospital-acquired infections such as BSI, PNA, or SSI. The risk of development of HAI should not be a deterrent to indicated transfusion, especially in hemorrhaging patients that may require massive transfusion. Further investigation is necessary to determine the relationship of transfusion-related immunosuppression with HAI.