I'm not one to transfuse blood at the drop of a hat. They are expensive and come with their own complications such as transfusion related lung reactions and exacerbation of heart failure. God forbid you get hepatitis B or C or even HIV from a blood transfusion. While all blood is screened and contracting a virus from a blood transfusion is uncommon, no test is 100%. The threshold for transfusing blood is one area of medicine that is highly individualized among physicians. Every doctor has their own threshold to transfuse blood. I don't know why that it. It shouldn't be like that. Transfusing blood should be a standardized process, much like the tPA criteria required for stroke patieints.
I use a hemoglobin of seven as my cut off when trying to decide whether to transfusion someone or not because that's what a nearly decade old study suggested was appropriate for critically ill ICU patients. However, if a patient has unstable hemodynamics, my goal is higher. If a patient is actively bleeding, my goal is higher. I just don't think there is a lot of data to tell docs what those goals should be.
We used to believe that having coronary artery disease was a prerequisite to transfusing to a goal hemoglobin of 10 or higher. But recent data ( I'm sorry, I can't find the source), suggests that goal is unnecessary. That makes sense if you can imagine how many of our chronic renal patients on dialysis have a hemoglobin permanently in the mid eight range and never have problems with their heart disease.
Sometimes, with regards to the complications of blood transfusions, less is more. The other day I tried to explain the risks of giving blood to an 88 year old woman admitted with cellulitis.
Happy: After this blood starts Mrs Smith, if you notice fangs starting to grow, you need to let the nurses know. You might be turning into a VampireMrs Smith: wide eyed and frozen with fear.Daughter: yelling at mom. Mom! Mom! Mom! He's just kidding. You're not going to turn into a Vampire.
That's not exactly the transfusion reaction I was expecting. This old lady someecard helps to explain: