Monday 6 May 2013

Emedinews:Tat Tvam Asi:Blood warmers


Tat Tvam Asi……..and the Life Continues…..
(Dr N K Bhatia, Medical Director, Mission Jan Jagriti Blood Bank)

Patients who receive refrigerated blood at rates faster than 100 mL/minute for 30 minutes have an increased incidence of cardiac arrest as compared with a control group receiving blood warmed to 37°C. Rapid infusion of large volumes of cold blood can lower the temperature of the sinoatrial node to below 30°C, at which point ventricular arrhythmias occur. Transfusions at such rapid rates generally occur only in the operating room or trauma settings. There is no evidence that patients receiving
1 to 3 units of blood over several hours have a comparable risk of arrhythmias; therefore, routine warming of blood is not recommended.

Several types of blood warmers are available: thermostatically controlled water baths; dry heat devices with electric warming plates and high–volume countercurrent heat exchangers with water jackets. Warming devices must not raise the temperature of blood above 42°C. Devices should have a visible thermometer and, ideally an audible alarm that sounds before the 42°C limit is exceeded. It is helpful for the standard operating procedure for warming blood to include guidelines on performing temperature and alarm checks, and instructions on what action to take when warmers are out of range.

Conventional microwave ovens and microwave devices for thawing plasma are not designed for warming blood and can damage red cells.

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