Lr. Sehgal et al., Evaluation of oxygen extraction ratio as a physiologic transfusion triggerin coronary artery bypass graft surgery patients, TRANSFUSION, 41(5), 2001, pp. 591-595
BACKGROUND: Approximately 20 percent of all allogeneic blood transfusions a
re administered in connection with coronary artery bypass graft (CABG) oper
ations. Transfusion practices vary across the country. The whole-body oxyge
n extraction ratio (O-2 ER) reflects the adequacy of the patient's response
to acute normovolemic anemia with an O-2 ER of approximately 50 percent be
ing shown to be an appropriate transfusion trigger. The present study monit
ored the O-2 ER in patients undergoing CABG and determined if transfusion p
ractices would have been different if an O-2 ER greater than or equal to 45
percent were used as a transfusion trigger.
STUDY DESIGN AND METHODS: Seventy patients with a postoperative Hct less th
an or equal to 25 percent were the test subjects. Arterial and mixed venous
contents were determined before the operation. in the intensive care unit
after the operation, and 12 hours after the operation.
RESULTS: There were no deaths. Forty-one patients received allogeneic trans
fusion. These patients were older, weighed less, and had a preoperative Hct
lower than the nontransfused patients. There were no significant differenc
es between transfused and nontransfused patients with respect to postoperat
ive Hct (21.0 +/- 0.4 vs. 22.2 +/- 0.4), cardiac index (2.5 +/- 0.1 vs. 2.7
+/- 0.1), O-2 delivery (6.4 +/- 0.3 vs. 6.7 +/- 0.3), O-2 consumption (2.5
+/- 0.1 vs. 2.5 +/- 0.1), and O-2 ER (38.3 +/- 1.7 vs. 37.5 +/- 1.5). In t
he transfusion group, 7 of 21 patients had a postoperative O-2 ER greater t
han or equal to 45 percent, while 3 of 35 in the nontransfused group had th
at result.
CONCLUSION: The use of O-2 ER as a transfusion trigger as part of a transfu
sion algorithm could lead to a reduction in allogeneic blood transfusion.