Discussion
Blood transfusions and re-exploration carry substantial risk for
postoperative morbidity and mortality and should be used
prudently.2-8,12,13 In a study of over 18,000 patients
at Cleveland Clinic from 2000 to 2010, Vivacqua et al noted that
transfusion and reoperation for bleeding were independently associated
with increased risk of mortality and morbidity, respectively (8.5% vs
1.8%).8 Mehta and colleagues noted a risk-adjusted
mortality of 5.9% for bleeding post CABG in patients who required
re-exploration compared to 2.0% for others.4 Ranucci
et al showed higher mortality (14.2% vs 3.4%; p = .001) and
greater morbidity in patients requiring surgical re-exploration compared
to patients who did not.5 In addition, the amount of
packed red blood cells was associated with significantly increased
morbidity and mortality (0.25% increase for each unit transfused). In a
study that included almost 5400 patients, Frojd et al noted a twofold
increase in early postoperative mortality and an increase in risk of
mortality beyond 90 days in patients requiring re-exploration for
bleeding.3 In an international prospective study of
patients undergoing urgent CABG with acute coronary syndrome on
antithrombotic agents, Stone et al noted that patients receiving
> 4 units of packed red blood cells was an independent risk
factor for mortality for up to 1 year after CABG.6Freeland and colleagues14 noted that blood transfusion
is an independent predictor of acute kidney injury in cardiac surgical
patients. Several studies have linked transfusions to potentially lethal
complications, including infection and lung
damage.15-18
The landmark paper in 1979 by Cosgrove and
colleagues19 showed that blood transfusions during
myocardial revascularization could be reduced to 6%. In his 2015
commentary, Svensson noted several important factors for achieving low
prevalence of transfusions, including tolerating lower hematocrits
on-pump and use of cell saver, among others.20 He
pointed out, however, that over time there has been an increase in
transfusions, perhaps attributable to greater use of anticoagulant and
antiplatelet agents and reduced concern regarding transfusion-related
infections.
Although the Society of Thoracic Surgery established guidelines in
200710 and 201111 for blood
transfusions, prevalence of transfusions in patients undergoing CABG
increased from 12% in 1999 to 32% in 20101 and is
likely associated with older age, increased comorbidities, and the
complexity and multiple component aspect of surgical procedures.
Nevertheless, only a small percentage of team members, including
perfusionists, anesthesiologists, and even surgeons, reported reading
the guidelines, implementing them, or altering practice
habits.1,21
Cost effectiveness and value-based medicine have become a cornerstone of
our health care system. Cardiac surgery accounts for a noteworthy
proportion of the 14 million annual RBCs transfused in the United
States.9,22 Shanders et al noted the cost of
transfusions to be US $1,158 per unit (2007 value) when indirect
overhead and acquisition costs are included, and even higher when
transfusion-related complications are considered.23 In
addition, the postoperative length of stay in the current study, was
significantly reduced to 4.5 days in the blood restricted group, adding
further cost savings as suggested and corroborated by
others.24,25
The lack of adherence to conservation measures may be because of the
assumption that restricting red blood cell use could be detrimental and
undermine patient safety. This is contrary to the findings of several
studies demonstrating the use of blood conservation techniques without
adverse consequences.26-28 Magruder and
colleagues29 noted significant variation in blood
transfusion practices even after risk adjustment, suggesting that
transfusion practices may be physician- rather than patient-driven.
Blood transfusions can be lifesaving and are more likely needed in
patients at higher risk of blood loss, such as those undergoing
reoperations, complex aortic, or valvular surgeries. As stated in the
Introduction, the reported prevalence of transfusions for primary CABG
is more than 32%, and the objective of this study was to concentrate on
the subset of patients in whom transfusion reduction could be
accomplished safely. A significant reduction in blood use for isolated
primary CABG following implementation of perioperative conservation
guidelines was observed, with no negative impact on patient safety or
outcome. Transfusions decreased intraoperatively and postoperatively,
resulting in a statistically significant decline in overall prevalence
of transfusions and postoperative length of stay.
These findings can likely be extended to other surgeries as well. Yaffee
and colleagues assessed a conservation strategy for aortic valve
replacement, emphasizing permissive anemia and minimization of
hemodilution (also through use of autologous priming and
vasopressors).30 They found a 14.9% decrease (82.9%
to 68.0%) in the number of patients transfused with RBCs, as well as a
54.4% reduction in overall mean blood product transfusions, with no
increase in mortality or major complications.30