The Body Cooling Unit Method for Treatment
Physiological Management
The B.C.U. operates on a straightforward, basic physiological principle. It's cooling power is analogue to that of the normal, overheated subject. By means of the B.C.U. the patient's heat is dissipated by evaporation of water from a warm skin. This reduces the internal body temperature, because heat is transferred efficiently to the skin by the increased blood circulation.
The machine keeps the whole of the skin surface wet by atomised spraying of clean water while holding the skin temperature above 32°C, and so maintaining an active circulation from core to skin surface. This is achieved by blowing warm air at the same time as the skin is sprayed. The fact that the skin remains vasodilated prevents shivering and keeps the patient comfortable, and evaporation is greatly enhanced by the high surface vapour pressure which wetting the skin at 32°C ensures.
The vessels in the skin remain dilated, and the flow of blood and, therefore, heat flow into the skin is maintained at a high level. The warm, carefully-wetted skin simulates sweating and provides a high vapour pressure which facilitates the removal of water vapour. The high rate of impinging air also increases the total volume of water vapour and heat removed.
The patient is suspended on a net over the bath so that the body is exposed to the spray from above and below. This has the advantage that access to the patient for ancillary treatment, blood pressure measurement, taking of blood, administration of oxygen and other nursing procedures is rendered very convenient.
In the B.C.U. this cooling process is achieved by keeping the skin temperature between 31°C-33°C, combined with complete wetting of the skin surface, and by providing continuous moving warmed air at a relatively low pressure. The cooling power of the B.C.U. is approximately three times that of the average person sweating at their highest rate.
Clinical Management
The efficient treatment of the patient requires
- Rapid and closely monitored body cooling. (The rectal temperature must be observed during and after cooling.
- At the same time clinical examinations are necessary for a complete evaluation of their condition. This includes pressure measurements, electrocardiogram recording and urine collections for laboratory tests.
- Appropriate treatment of the derangements brought about by hyperpyrexia, particularly convulsions, coma, respiratory failure, e.g., in most cases oxygen needs to be given.
- Keeping the patient free of vomit and faecal material.
- Transfusion of saline and other fluids.
The B.C.U. is designed to enable all these operations to be carried out effectively and hygienically. The basic method is the suspension of the patient on a net over a bath unit. The bath enables faeces and vomit to be washed out and drained away. The patient can be restrained, if necessary. Access to the patient by the medical attendants is possible from both sides.
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