Blood Transfusion Guidelines

Temperature Considerations

Blood transfusion is safe at a patient temperature of 99.7°F, as this represents only a mild elevation from normal body temperature (98.6°F/37°C) 1
The primary temperature concern in transfusion medicine is actually hypothermia, not mild fever, especially in patients with hypotension who may require rapid transfusion 1, 2
Hypothermia (temperature <35°C) is associated with increased mortality, blood loss, and transfusion requirements in trauma patients 1, 2

In all adults undergoing surgery under general or regional anesthesia, blood components should be warmed to 37°C when transfusing volumes of 500 mL or more 3, 4
Blood should only be warmed using approved, specifically designed and regularly maintained blood warming equipment with a visible thermometer and audible warning 3, 5
The greatest benefit of warming is from controlled warming of red cells (stored at 4°C) rather than platelets (stored at 22±2°C) or FFP/cryoprecipitate (thawed to 37°C) 3

For patients with hypotension, blood transfusion is often indicated as part of resuscitation, especially when the hypotension is due to hemorrhage 6
When transfusing hypotensive patients, consider using rapid infusion devices which typically have a range of 6-30 L/h and usually incorporate a blood-warming device 3, 4
For patients with ongoing bleeding, aim for a hemoglobin target of 7.0-9.0 g/dL during active resuscitation 6

Monitor the patient's hemodynamic status throughout the transfusion, including blood pressure and heart rate 6
For patients with hypotension, monitor for signs of end-organ perfusion including ST changes, oxygen saturation, ECG, urine output, and arterial blood gas analysis 6

If the patient's hypotension is severe (systolic BP <90 mmHg), consider damage control resuscitation strategies 2, 7
Consider using tranexamic acid in the setting of massive hemorrhage, particularly with a loading dose of 1 g over 10 min followed by 1 g over 8 h 3, 8

Do not delay transfusion in a hypotensive patient due to mild temperature elevation (99.7°F) as this does not represent a contraindication 1, 2
Avoid allowing blood to cool during rapid transfusion as hypothermia worsens coagulopathy and increases mortality 1, 2
Remember that a 1°C drop in body temperature is associated with a 10% drop in coagulation factor function, so maintaining normothermia is critical 1, 2

Each 1°C drop in body temperature causes a 10% reduction in coagulation factor function, which can worsen outcomes in patients requiring transfusion, according to the Critical Care society 9, 10

Early application of measures to reduce heat loss and actively rewarm the hypothermic patient is a Grade 1C recommendation, as stated by the Critical Care society, to target normothermia (36-37°C) and create optimal conditions for coagulation 9, 10
Removing wet clothing immediately and shielding the patient from further heat loss is recommended by the Critical Care society to reduce heat loss and rewarm the patient 9, 10

Patients with coronary artery disease should be transfused at hemoglobin <8.0 g/dL, as recommended by the Annals of Surgery society 11
Patients with angina, heart failure, or on beta-blockers should be transfused at hemoglobin <10.0 g/dL, according to the Annals of Surgery society 11
Patients on cardiopulmonary bypass with moderate hypothermia should be transfused at hemoglobin <6.0 g/dL, as stated by the Annals of Surgery society 11
Patients at risk of critical end-organ ischemia should be transfused at hemoglobin <7.0 g/dL, according to the Annals of Surgery society 11

Standard coagulation tests (PT/aPTT) performed at 37°C underestimate the severity of coagulopathy in hypothermic patients, as noted by the Critical Care society 9, 10
The coagulopathy effects are only detectable when tests are performed at the patient's actual low temperature, according to the Critical Care society 9, 10