an assessment of RADIO FREQUENCY INDUCTION HEATING OF BLOOD for massive transfusion

Pioneers in South African Anaesthesia:

“…(See Figure 1) In 1967 the UCT group published an investigation into the efficacy of the new Taurus Blood warmer to heat blood uniformly, to stop heating at the desired temperature and to preserve red blood cells after transfusion. 2 This study demonstrated that the relay circuit was reliable in terminating the heating process, initially using bottles of 0.5% saline that has a similar conductivity to blood, and subsequently with blood of varying shelf life. It also demonstrated uniform heating of blood with a temperature gradient difference of less than 0.5 o C throughout the bottle.…”

“…Prior to its development blood warming strategies were largely inefficient and unsafe. 1,2 The commonest forms of blood warming at the time were either immersion of the bottles of blood in a warm bath, which was slow, or the use of heat exchangers consisting of a long length of coiled tubing up to 24 feet. The tubing was passed through a water bath, making it ineffective at the high flow rates needed for rapid transfusions due to its high resistance.…”

“…1,2 deleterious effect on whole blood, should be effective at high transfusion rates (>150ml/min), must be rapidly assembled, and be simple to use. 2 The research team, led by Dr J Besseling and Associate Prof Bull, chose radio-frequency induction as the means most likely to heat blood contained in a standard Baxter blood bottle rapidly and evenly. 1 To achieve this, a poweroscillator circuit was designed to provide a suitable electro-magnetic field at a frequency of 33 MHz capable of producing the 250W of energy required for this purpose.…”

“…1,2 Electrically blood can be regarded as an inhomogeneous dielectric in which the conductivity increases with increasing temperature, producing a variable load to the radio-frequency circuit. 2 This phenomenon was used to create an electrical balance, which could act as a relay to terminate the heating process at a desired temperature, eliminating the risk of excessive heat damage. The process was patented in South Africa and the Taurus Mark II blood warmer was manufactured under licence by Plessey.…”

Anaesthesia – what has the University of Cape Town contributed?

“…In 1965 -1967 the Taurus blood warmer -named after Professor Bull -to prevent hypothermia after major blood transfusion was developed. 2 This device, still in use today, was one of the first to use radiofrequency induction heating technology. The pressure-cycled Bird ventilator was modified for use in both paediatric and adult anaesthesia.…”