Generally, when you donate blood and is not transfused to a patient at that time, it has to be stored in a refrigerator so as to enhance its life. Obvious, the temperature in a refrigerator is far much below the normal body blood temperature. It happens that this ice-cold fluid is transfused into the body system, conditions like hyperthermia, arrhythmias, and shock are likely to occur. That is why reusable blood warmer are used so as to provide the fluid with the necessary and appropriate temperature before being incorporated into the body.

They are classified in three categories following the technology or technique used to provide heat. They include dry heat that uses hot air, water bath devices that use hot water as a heating medium and lastly the countercurrent machines which use electric power to provide heating. The process of raising the temperature is usually done in the cabinets before being transfused into the patient or in line during the transfusion activity.

However, they are made without the ability to maintain or retain temperature. Once they make the fluid reach the set temperature, they cannot maintain that range until restarted. That is why, when the device accomplishes the goal, that is raising the temperature to around 37 degrees Celsius, it is now taken into the patient body. If this is not done, the fluid is likely going to lower the temperature again.

In most cases, these devices are used during mass transfer of blood or to patients who require more than fifty percent of the body blood volume. They are also used when the volumes to be administered requires urgency or need to be done rapidly. This is because, if a large amount is transfused when cold the mentioned cases are likely to occur due to temperature lowering beyond the recommended range. They are also used when the patients receiving the blood have cold agglutinins.

However, it is important to have certain specific considerations before administering the procedure to patients who are elderly, pediatric, neonates, as well as those with chronic infections and cardiac dysfunction. However, the device should be operating before the entire exercise begins. One of the reasons being that it cannot be switched on, at the same time, it is has provided the required temperature.

It is an advantageous device as the patients are able to attain the required body temperatures and any side effect of low or cold temperatures is eradicated. Another benefit of this device is that it does not get disposed of together with the bags and storage. It is used again and again. In the case of countercurrent, it only requires fixing it to the bag or the body and switching it on and starts operating.

However, it has certain limitations such as failure or temperature maintain technology. It can only prevent loss of heat by active warming but does not have a way in which the patient can be kept warm. That is why other methods like warming, water, blankets as well as pads can be used as another way or remedy to conditions like hypothermia.

They are not effective in providing warmth as other ways like using hot water baths, blankets, and pads do better than them in reducing hypothermia. However, their use cannot be compared with cold transfusions.