Unwashed shed blood infusion causes deterioration in right ventricular function after coronary artery surgery

Blood use in elective surgery: the Austrian benchmark study

BACKGROUND

Benchmarking transfusion activity may help to eliminate inappropriate use of blood products. The goal of this study was to measure and to compare the current transfusion practice and to identify predictors of transfusion in public hospitals to develop strategies to optimize transfusion practices.

STUDY DESIGN AND METHODS

This was a prospective observational study in 18 randomly selected public hospitals from April 2004 to February 2005. Primary outcome measures were the amount of intra- and postoperative blood components transfused and intercenter variability of transfusion rate. Secondary outcome measures were prevalence of preoperative anemia, calculated perioperative blood loss, and lowest measured perioperative hemoglobin (Hb) level.

RESULTS

Adult patients undergoing primary unilateral total hip replacement (THR, n = 1401), primary unilateral knee replacement (TKR, n = 1296), hemicolectomy (HECOC, n = 148), and coronary artery bypass graft (CABG) surgery (n = 777) were enrolled. Due to the small number, data of HECOC patients were not fully analyzed. In the remaining procedures, there was a large intercenter variability in the percentage of patients who received transfusions: THR 16 to 85 percent, TKR 12 to 87 percent, and CABG 37 to 63 percent. In the patients who received transfusions, the number of red blood cells (RBC) units transfused varied significantly. There was also a considerable intercenter variability in RBC loss. The prevalence of preoperative anemia was 19 percent and identical in both sexes. The incidence of preoperative anemia was three times higher in patients who received transfusions compared to those who did not.

CONCLUSION

This study demonstrates a high intercenter variability in RBC transfusions and RBC loss in standard surgical procedures. Whereas the variability in blood loss remains largely unexplained, the main predictors for allogeneic RBC transfusions are preoperative and nadir Hb and surgical RBC loss.

Decreased right ventricular function after coronary artery bypass grafting and its relation to exercise capacity: A tricuspid annular motion–based study

BACKGROUND

Decreased right ventricular (RV) function is a known echocardiographic finding after coronary artery bypass grafting (CABG). For patients with heart failure, RV dysfunction is a predictor of poor exercise capacity. The significance and time course of RV dysfunction and its relation to exercise capacity after CABG have not been elucidated, however.

OBJECTIVES

In this prospective study, we assessed RV function measured from echocardiographic tricuspid annular motion (TAM) before and after CABG and its relation to exercise capacity.

METHODS

In 99 patients accepted for CABG, we did a baseline echocardiographic investigation before operation, followed by repeated echocardiograms 3 months and 1 year after CABG. RV function was assessed using the magnitude of TAM measured at the RV free wall. An exercise stress test and coronary angiography were performed before and 3 months after CABG.

RESULTS

RV function assessed by TAM was significantly reduced 3 months after CABG (22.4 vs 14.5 mm, P <.001) compared with preoperative measurements and remained so after 1 year (14.7 mm, P <.001). Left ventricular systolic function was unchanged 3 months after CABG. The 1-year echocardiographic follow-up showed paradoxical septal movement in 96% of the patients. Exercise capacity improved significantly 3 months after CABG compared with before (1.6 vs 1.83 W/kg, P <.001). These finding are independent of the state of the right coronary artery.

CONCLUSIONS

One year after CABG, RV function remained depressed and septal motion remained paradoxical compared with the preoperative investigation, suggesting that these postoperative findings might be permanent in the majority of patients. Despite the reduced RV function, exercise performance 3 months after CABG was improved. The depressed RV function, measured from TAM after CABG, probably lacks clinical significance.

Safety and efficacy of methods for reducing perioperative allogeneic transfusion: a critical review of the literature

A number of pharmacologic and nonpharmacologic technologies are in current use to minimize perioperative homologous blood use. Clinical trials, many of them randomized controlled trials, have been done evaluating these approaches and have demonstrated their efficacy. However, data on safety has relied mostly on case reports, uncontrolled studies, and, for the pharmacologic agents, extrapolation from the nonsurgical setting. In this review I analyze the data from the randomized trials and the lower-level evidence studies to provide the best estimates in safety with these alternatives. In general, these alternatives are safe with proper dosing and monitoring of effects. With aprotinin, the primary concern is anaphylaxis, and this predominantly with re-exposure. With aprotinin and with the anti-fibrinolytics, increased venous thromboembolic risk has not been a consistent finding. Tranexamic acid use intraoperatively is advantageous, but postoperative use appears to have no advantage and may be associated with renal dysfunction. DDAVP is low-risk, provided it is not overused, which can induce hyponatremia. Autologous predonation probably has similar risks as homologous blood with respect to transfusion errors and bacterial infection. As with most medical interventions, we must be vigilant to prevent human error.

Troponin I concentrations of shed blood might influence monitoring of myocardial injury after coronary operations

In a prospective study we evaluated the concentration of cardiac troponin I (cTnI) and creatine kinase activities (CK) in shed mediastinal blood in the early postoperative period after coronary artery bypass grafting (CABG). Forty seven patients who underwent first time elective CABG were studied. CTnI levels and CK activities in arterial blood and shed mediastinal blood were measured after admission to the intensive care unit (ICU) and 6 h after unclamping the aorta. Mediastinal shed blood samples were drawn from 23 patients (group A) before the filter of the cardiotomy reservoir and from 24 patients (group B) behind. Additionally, both markers were measured in blood samples collected from the cell-saver. There were no significant differences between both groups (A and B) with regard to perioperative parameters. Mean loss of mediastinal shed blood in all patients was 207 +/- 127 ml within the first 6 h after operation. There was a positive correlation between CK activities and cTnI concentrations in serum and mediastinal shed blood, but shed blood contained significantly higher concentrations of cTnI as well as CK activities than the circulating blood after admission to the ICU and 6 h after unclamping the aorta. At both time points the cTnI-concentrations and CK activities in shed blood in group B were lower than those in group A but much higher than in serum. The effects of the use of a blood filter diminishes with time. Mediastinal shed blood contains extremely high cTnI concentrations and CK activities. Retransfusion of higher quantities of shed blood might lead to false-positive diagnosis of perioperative myocardial infarction.