Many guidelines recommend transfusion if the patient's hemoglobin (Hb) level falls to 7 to 8 g/dL, but some researchers think that using a fixed trigger point may be deleterious to patients.
Here's a conundrum: The ideal trigger point for transfusion during or after surgery is unclear. Many guidelines recommend transfusion if the patient's hemoglobin (Hb) level falls to 7 to 8 g/dL, but some researchers think that using a fixed trigger point may be deleterious to patients. Their reasoning is that some individuals may experience inadequate tissue oxygenation even with Hb concentrations higher than 8 g/dL. They suggest that the percentage of change between the preoperative Hb level and the nadir Hb level (ΔHb) may be a better predictor of adverse outcome.
A recent issue of JAMA Surgery included a study addressing this possibility. In it, researchers from the Department of Surgery at Johns Hopkins Hospital in Baltimore, MD, evaluate the association between ΔHb and morbidity in patients who undergo major gastrointestinal surgery as an independent factor or combined with the nadir Hb concentration.
These researchers retrospectively reviewed data from 4669 patients who underwent major gastrointestinal surgery (pancreatic, hepatic, or colorectal resection) from January 1, 2010, through April 30, 2014. They determined ΔHb concentration following surgery, nadir Hb level, and overall perioperative blood loss.
Patients' median ΔHb level after surgery was 40%. Having multiple comorbidities or undergoing pancreatic surgery doubled the risk of a ΔHb of 50% or greater.
Patients with a ΔHb level of 50% or greater whose nadir Hb level was less than 7 g/dL had elevated risks of developing postoperative complications compared to patients with better Hb parameters. Patients whose ΔHb level was 50% or greater were almost 6 times more likely to experience ischemic complications, even if their Hbs level exceeded 7 g/dL.
Symptoms of anemia and intravascular volume signal a need for PRBC transfusion to avoid anemia-related ischemic injury, but they are subjective and very hard to assess quantitatively. Using ΔHb level may reduce risk of postoperative morbidity and be as good a trigger point as a specific Hb level (or better) to determine if transfusion is needed.