What Is A Blood Transfusion, Truly?

Many ICU patients suffer from anemia. Some are chronically anemic, and others develop anemia due to their acute illness (such as bleeding, for example). Multiple specialty societies have developed guidelines over when to transfuse red blood cells, and they are listed below (courtesy of the PulmCCM Substack):

Generally Critically Ill Patients

Association for the Advancement of Blood and Biotherapies (AABB) and the European Society of Intensive Care Medicine (ESICM) advised a transfusion trigger of hemoglobin less than 7 g/dL.

Active GI Bleeding

Patients with active gastrointestinal bleeding should also usually be managed with a restrictive transfusion threshold (hemoglobin target >7.0 g/dL), according to U.S. critical care and gastroenterology societies.

Surgical Patients

For patients undergoing cardiac surgery,

• AABB and ESICM advised a hemoglobin transfusion threshold of 7.5 g/dL.
• A U.S. critical care society recommended a target of 7.5 to 8.0 g/dL.

For patients undergoing orthopedic surgery, AABB recommended a threshold of 8 g/dL.

Acute Coronary Syndrome

• ESICM weakly recommended a target hemoglobin of 9 to 10 g/dL using low-certainty evidence.
• A U.S. critical care society recommended against using a restrictive strategy (Hb 7 to 8 g/dL) based on trials using 10 g/dL as the permissive comparator.
• AABB declined to advise on thresholds for transfusion during acute myocardial infarction.

Stable Cardiovascular Disease

AABB advised a transfusion threshold of 8 g/dL for patients with chronic cardiovascular conditions.

A U.S. critical care society advised a restrictive strategy (targeting hemoglobin 7 to 8 g/dL) in patients with isolated elevated troponin levels who are not experiencing acute coronary syndromes.

Despite these guidelines, however, many clinicians still will transfuse at higher thresholds. The PulmCCM Substackdelineated some of the possible reasons why:

Might this patient have undiagnosed severe coronary artery disease?

What if this “stable” GI bleed becomes massive overnight?

The blood pressure is normal, but trending down—is this impending shock?

Is there an unrecognized bleed somewhere, and the hemoglobin hasn’t yet equilibrated?

What if follow-up labs aren’t drawn on time, or result late after my usual AM check?

As a practicing clinician myself, I can understand this caveats in the minds of fellow clinicians. At the same time, we need to remember what a blood transfusion really is: it is a tissue transplant.We are taking someone else's tissue, namely the blood products, and transplanting them into the body of another patient. This is no small thing.

Now, when a blood transfusion is indicated, it is absolutely life-saving, such as when a patient is having massive bleeding and needs aggressive resuscitation with blood products.

At the same time, if a patient is hemodynamically stable and not actively bleeding, the preponderance of the medical evidence - greatly outlined in the PulmCCM article - shows that patients are not harmed if we wait to transfuse when the hemoglobin level decreases below 7 g/dL (except maybe patients with active heart attack). We need to heed these guidelines.

Finally, a huge thank you to all those wonderful people who donate their blood. They take time out of their busy lives to give of their own life preserving tissues for the sake of others, complete strangers. Their sacrifices should not be overlooked. In my book, they are just as much healthcare heroes as the bedside clinicians.

Thank you!