For many years, it has been accepted that patients get cold during surgery. This is due to a combination of factors: heat loss to the environment, the action of anaesthetic drugs and the administration of cold fluids.
In certain types of surgery, and with surgery time, this presents a risk of inadvertent peri-operative hypothermia.
Additionally, shivering on waking from anaesthesia is not only unpleasant, but is a risk factor for cardiovascular complications. Studies have shown that vasoconstriction and intra-operative hypothermia slows bleeding and increases the risk of surgical site infection, in addition to reducing platelet activity, hindering coagulation. Revised NICE guidelines have also calculated significant net monetary benefit per case of averted hypothermia.
There are a number of methods used to keep patients warm, which include traditional methods such as the use of blankets and gels. Twenty five years ago Dr Scott Augustine (Minnesota, US) and his team invented forced-air warming (FAW). At that time, the FAW device was considered an innovative way to appropriately deal with patient warming and the prevention of hypothermia.
However, with latest research, health economic pressures and increasing concern over patient warming methods in ultra-clean surgeries, there was a clear need to evolve technology. After decades of research, the Augustine Temperature Management (ATM) team set out to develop a new system that accurately addresses the needs of healthcare providers. The result is an innovation that is safe, cost-effective and appropriate for all types of surgery, and can warm the patient pre- and post-operatively.
HotDog is an air-free, water-free, gel-free, state-of-the-art, peri-operative warming system. The technology features a semiconductive polymer fabric, Thermasure, which is a unique, patented technology. The HotDog controllers deliver low voltage to the specialised blankets and mattress overlays via flexible cables, where it is converted efficiently into safe heat.
The revolution is in the heating; unlike heated wire or carbon fibre technologies, Thermasure heats evenly over the entire surface of the blanket even under contoured conditions. Low watt density and low thermal mass means safe and effective conductive warming.
The blankets are flexible, easy to use, lightweight and radio-translucent over most of the surface. Temperature is measured and regulated at the patient via a primary and secondary sensor, which is in direct contact with them. The controller comprises a microprocessor that ensures correct function and will turn the blanket off if it detects abnormal conditions. Even if the blanket is cut or punctured, it is completely safe.
The system warms the patient from above and below simultaneously via a single controller, resulting in a uniquely versatile, less expensive and more effective warming solution. In a prospective, randomised controlled trial, conductive fabric warming (HotDog) showed significantly higher warming rates than forced-air warming (FAW) (0.35˚C/hr versus 0.02˚C/hr), when all other relevant variables were held constant.1
The aim of the ATM team was to develop a system that is economically favourable compared with other types of patient warming. The all-in-one concept (pre-, peri- and post-operative warming) enhances the cost benefits even more
It is a much less expensive option than disposable forced-air warming gowns and blankets. In a study involving five independent hospitals in the US, some of which were using forced air, while others were using more traditional methods, a switch to HotDog resulted in an average saving of 52% in a year, and cost per patient for peri-operative warming averaging only $2.89 (about £2.30). This is not only because of its versatility, but also because the product has reusable components, and the system can be acquired via flexible purchase models so that hospitals can realise cost-per-patient benefits.
The system has proven especially popular in areas such as orthopaedics, where it eliminates concerns over disruption of clean air in laminar flow theatres, and offers distinct practical advantages in areas such as cardiothoracic and paediatrics.
The good news for the UK is that ATM recently announced a new distributor arrangement: novus med, who specialise in bringing new medical innovation from across the globe into the UK healthcare setting, are now sole UK dealers for the product. Furthermore, it is available on a no-risk, flexible, Monthly Warming Plan through novus med.
1 Hayashi H, Koizumi T, Sumita S, Yamakage M. Relative clinical heat transfer effectiveness: forcedair warming vs conductive fabric electric warming. ASA abstract2015. Submitted for publication.
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