Transfusions and Fluid Management
Although blood transfusions have obvious beneficial effects, including reversal of shock and improved patient survival after acute hemorrhage, they may also have significant adverse effects including an increased incidence of infection, pulmonary dysfunction, promotion of tumor growth, and transmission of infections. By 1990, there were 13 studies (6 prospective) that demonstrated that perioperative blood transfusion was an independent predictor of infection. These studies included patients with abdominal surgery, open heart surgery, orthopedic surgery and burn injury. All of them showed an increase in wound infection and all but 2 reported an increase in other types of infections such as urinary tract infections or pneumonia. A dose/response was reported in 7 of the studies but was not recorded in 4.
A dose/response has also been reported in most of the subsequent publications. In a group of 548 patients undergoing abdominal operations, septic complications occurred to a greater degree in patients receiving more than 3 units of blood (SDC-240). In 868 patients with acute injuries, the corrected odds ratio for infection was 1.6 when 1 to 4 units were given but 6.4 when more than 4 units were given (SDC-241). In 285 patients undergoing elective operations for gastrointestinal cancer, blood transfusion was an independent variable when more than 1000 mL was transfused (OR = 6.5) (SDC-242). Both buffy-coat depleted packed red cells and white cell reduced (filtered RBC) showed an increase in postoperative infections in a study of 697 patients with colorectal surgery, compared to no transfusion, with a corrected relative risk of 1.6 for 1 to 3 units of red cells and 3.6 for more than 3 units (SDC-243).
In a single center study involving 15,592 cardiovascular operations, blood transfsions were associated with an increased dose dependent incidence of both wound and systemic infections (SDC-244). A report from a large shock-trauma center studied the risk-adjusted outcome in 1172 consecutive trauma patients with stratification for the type of blood product. The risk of infection increased by 5% for every unit of packed red blood cells.
There is some evidence that the incidence of infection increases proportional to the length of storage of the blood. In one study of colorectal rectal resections, blood stored for 21 or more days had an overall infection rate, which was higher than blood stored for shorter periods, 46% versus 32% (SDC-245). Another study showed that the risk of pneumonia increased 1% per day with each day of storage of the transfused blood (SDC-246). In an analysis of more than 6000 cases of cardiac surgery, blood stored 14 days or less was associated with a 2.8% incidence of sepsis or septicemia compared to 4.0% with blood stored at least 15 days, but length of storage had no effect on deep sternal wound infections (SDC-247).
There is considerable controversy concerning whether the non red blood cell components of transfusion are associated with an increased incidence of infection. Five hundred eighty-six patients scheduled for elective colon surgery were randomized to leukocyte-depleted or buffy coat poor blood. The patients with buffy coat poor transfusions had a higher frequency of wound infection (12% vs 0%) (SDC-248). A recent meta-analysis of 12 randomized controlled trials concluded that transfusion with buffy coat reduced red blood cells after storage compared to WBC reduction before storage was associated with an increase in infection (SDC-249). There is now good evidence that there is a higher risk of death in association with WBC containing allogeneic blood transfusions, especially after cardiac surgery.
Because allogeneic blood is associated with an increase in the incidence of wound infections and overall infections, it has seemed reasonable that the use of autologous blood donated before operation would reduce infections. Indeed, this seemed to be true in one study of 385 patients undergoing elective orthopedic surgery where the postoperative infection rate was 4.6% in patients receiving no transfusion or autologous transfusions compared to 11.9% after allogeneic transfusion (OR = 2.8) (SDC-250). In a follow-up study by the same group, 6.9% of patients without transfusion, 1.2% of patients with autologous transfusion and 12% of patients with WBC filtered RBCs developed infections (SDC-251). In a study of resections for colorectal cancers, transfusion of autologous blood was associated with fewer postoperative infections (14%) than transfusion of homologous blood (33%) (SDC-252). However, the use of autologous blood has not been shown to reduce infections in other studies (SDC-253). Use of a cell-saver has been advocated as a way to decrease the number of allogeneic transfusions, but at least one study has shown that the rate of infection was not decreased by using this technique (SDC-254).
The conclusions that transfusions increase the susceptibility to microbial infections are not entirely without concern because these observations have occurred primarily in patients with trauma or major surgical procedures, and contributing factors cannot always be eliminated in as much as transfusions are more often given to the sickest patients, having other conditions which are clearly associated with infection such as age, length of operation, anesthesia risk, diabetes, and so on. Multivariant analyses have helped to reduce these concerns and the fact that transfusions increase the susceptibility to infections is now supported by several animal studies (SDC-255-259).
Fluid management during an operation could also have an effect on wound infections. It is now clear that restrictive fluid administration during many operative procedures may be beneficial compared to liberal administration of fluids, and this may be important in the development of wound infections in as much as Ringers' solution as the sole means of fluid may reduce mean oxygen tension for 24 hours postoperatively by as much as 23% (SDC-260-261). In a prospective randomized study, fluid restriction decreased wound complications from 25% to 13% (SDC-262).
Virtually, all reports show an increased incidence of infection in transfused surgical patients, but some studies are difficult to interpret because of lack of comparability between transfused and nontransfused subjects. However, multifactoral analyses and animal studies show that there is a clear causal relationship between blood transfusion and the development of infections. The effect increases with the number of transfusions given, and there is some evidence that early leukocyte reduction by filtration will partially, but not completely, reduce the effect on wound infections. Blood transfusion is associated with alterations of a large number of immunologic mechanisms involving almost every segment of the immune response, the most important of which may be macrophage functions. As discussed before, anything that decreases the delivery of oxygen to a wound can increase the incidence and severity of infection. Administration of excessive amounts of crystalloids should also be avoided as this could possibly decrease tissue oxygen tension.
Annals of Surgery. 2011;253(6):1082-1093. © 2011 Lippincott Williams & Wilkins
Cite this: Updated Recommendations for Control of Surgical Site Infections - Medscape - Jun 01, 2011.