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Status: Pilot Complete

Number Participants: 515

Number Centres: 6

Registration:  ISRCTN74612906

Funding:  3MTMHealthcare Infection SocietyUniversity of Oxford

Hip fractures following a fall are common in older people because they often have weakened or brittle bones. In most cases, surgery is the only treatment option. There are currently about 70,000 operations per year in the UK to repair hip fractures with around 2.5% of cases developing serious infections after the surgery. Deep surgical site infections can lead to the need for further surgery, problems with recovery and long-term treatment with antibiotics which is neither good for the patient nor for the health economy and overuse of antibiotics is encouraging the emergence of antibiotic resistance.

The risk of developing a surgical site infection is reduced by preventing the patient from becoming too cold (hypothermic) during the surgery. Different methods of keeping patients warm are used in different hospitals. The method used most often is called Forced Air Warming. It keeps patients warm with hot air but there are concerns that blowing hot air in the operating theatre may alter the sterile environment during surgery. An alternative method used in some hospitals is called Resistive Fabric Warming. It is like an electric blanket and can keep patients warm without blowing hot air in the operating theatre.

In the long-term, the aim of this study is to compare these two warming methods to see if fewer surgical site infections develop with one technique than the other. We have conducted a pilot study to check that we would be able to recruit enough participants for a full clinical trial. The pilot study demonstrated robust recruitment and data management strategies and that both Forced Air Warming and Resistive Fabric Warming are safe to use and effective at maintaining normothermia. Surgical site infections were observed in both groups. Due to its size, no statistical comparisons of infection could be made from the pilot study.

Funding is now sought to conduct an adequately powered full trial.

Detailed analysis from participants whose temperatures were recorded by zero-flux thermometry showed that Resistive Fabric Warming is a viable alternative to Forced Air Warming for maintaining normothermia following hemiarthroplasty in the elderly, despite current guidelines saying that it should only be used if Forced Air Warming is not available.


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Resistant Fabric Warming is a viable alternative to Forced Air Warming to Prevent Inadvertent Perioperative Hypothermia during Hemiarthroplasty in the elderly. Michelle Kümin, Christopher Iain Jones, Alex Woods, Stephen Bremner, Mike Reed, Matthew Scarborough and C Mark Harper.  J Hosp Infect. (2021) 118: p.79-86.


Reducing Implant Infection in Orthopaedics (RIIiO): Results of a pilot study comparing the influence of forced air and resistive fabric warming technologies on postoperative infections following orthopaedic implant surgery. Kümin M et al. J Hosp Infect. (2019) 103: p.412-419.


Reducing Implant Infection in Orthopaedics (RIIiO): a pilot study for a randomised controlled trial comparing the influence of forced air versus resistive fabric warming technologies on postoperative infection rates following orthopaedic implant surgery in adults. Kümin M et al. Trials. (2018) 19;19(1):640


Laminar flow ventilation during surgery. Kümin M, Scarborough M. Lancet Infect Dis. (2017) 17(6):581