A blood warmer heats blood or fluids prior to transfusion into a patient. It can be used when there are concerns about transfusing a large volume of cold fluids. This could be necessary in cases where patients have experienced massive trauma and need large transfusions, or when they are fragile for medical reasons. Once a patient’s body has started to cool, however, a blood warmer will not offer significant benefits; it is designed to prevent heat loss, not to reverse it.
The device holds an infusion bag of blood, fluids, or solutions and heats it to a set point that will be safe for the patient before running it through an infusion pump. Nurses and technicians can control the temperature as well as the infusion rate. Blood warmers can be used in emergency settings, operating rooms, and intensive care units to provide warm blood and fluids to patients who need them, and a hospital may keep multiple warmers on a floor to ensure one will always be available.
Using a blood warmer is indicated when more than 50% of the patient’s fluid volume is going to be replaced with a transfusion, or when blood is going to be infused very rapidly. Another consideration can be in surgery where several units of blood are necessary, and more might be needed later. To reduce the risk that the patient develops hypothermia from too many units of cold blood, a blood warmer can be used. It is important to set up the warmer in advance, because it needs some time to work, so if nurses think one might be needed, they may start pre-warming it to make it readily available.
Instead of using a blood warmer to address concerns about possible heat loss, other options can include warming blankets or pads for the patient. These warm the whole body to offset hypothermia and keep the patient warm and comfortable. For patients who are at risk of developing hypothermia because of their medical condition, simply warming fluids may not be enough, and these measures could be more appropriate.
Once hypothermia sets in, the patient needs to be warmed by other measures. Infusing warm fluids will not help the patient warm up, although they can be part of treatment to prevent further heat loss as the patient is treated. Hypothermia care can involve slowly raising the patient’s temperature to prevent complications, using a variety of means.